Electromagnetic interferance (EMI) mitigation for power conversion

Abstract

Systems, methods, and media for power conversion with electromagnetic interference (EMI) mitigation. The power conversion includes a variable-frequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes. The variable-frequency power converter includes a DC link capacitor connected across the DC bus and a half-bridge circuit with power switching elements and an LC filter. The power conversion further includes an EMI filter connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node. The power conversion further includes a control system coupled to the variable-frequency power converter, the control system is configured to control the variable-frequency power converter to convert power.

Description

Atlomey Docket No.: 175073.00303ELECTROMAGNETIC INTERFERANCE (EMI) MITIGATION FOR POWER CONVERSIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 709,359, filed on October 18, 2024, the contents of which are hereby incorporated by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] N / ABACKGROUND

[0003] Power converters of various types have been produced and used in many industries and contexts. Example power converters include alternating current (AC) to direct current (DC) rectifiers, DC to AC inverters, and DC to DC converters. AC to DC rectifiers, also referred to as AC / DC rectifiers, convert AC power to DC power. DC to AC inverters, also referred to as DC / AC inverters, convert DC power to AC power. Power converters can be used for various purposes, such as rectifying AC power from an AC grid power source to DC power for charging a battery, or inverting DC power from a battery to AC power to drive a motor or supply AC power to an AC grid. Further, power converters can be used in various contexts, such as in or connected to an electric vehicle, an engine generator, solar panels, and the like.SUMMARY

[0004] In some examples, a power converter system is provided that includes: a variablefrequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the variable-frequency power converter including: a DC link capacitor connected across the DC bus, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a-1-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 second capacitor, wherein the first and second capacitor are connected at a ground node; and a control system coupled to the variable-frequency power converter, the control system is configured to: control the variable-frequency power converter to convert power.

[0005] In some examples, a method is of converting voltage is provided. The method includes: determining, by a control system, at least one electrical operational characteristic for a variable-frequency power converter, the variable-frequency power converter including: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node a switch-side section including connection nodes, a DC link capacitor connected across the DC bus, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; determining, by the control system, a duty cycle and a switching frequency based on the at least one electrical operational characteristic; driving the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency; and filtering, by an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, power at the DC voltage section or at the switch-side connection, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.

[0006] In some examples, a non-transitory computer readable medium including instructions stored thereon is provided. The instructions, when executed by a computer, control a computer to: sweep control signals that drive a variable-frequency converter circuit to drive the variable-frequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different combinations of duty cycles and switching frequencies; determine a setpoint of the range of setpoints that results in peak electromagnetic interference (EMI) by the variable-frequency converter circuit; generate filter component values for an EMI filter of the variable-frequency converter based on the setpoint determined to result in peak EMI; and provide a modified variablefrequency converter circuit having the EMI filter with the filter components values.

[0007] In some examples, a method is of converting voltage is provided. The method includes: sweeping control signals that drive a variable-frequency converter circuit to drive the variable-frequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different-2-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 combinations of duty cycles and switching frequencies; determining a setpoint of the range of setpoints that results in peak electromagnetic interference (EMI) by the variable-frequency converter circuit; generating filter component values for an EMI filter of the variable-frequency converter based on the setpoint determined to result in peak EMI; and providing a modified variable-frequency converter circuit having the EMI filter with the filter components values.

[0008] In some examples, a power converter system is provided that includes: a variablefrequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the power converter including: a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; and a control system coupled to the variablefrequency power converter, the control system is configured to: determine PWM operational parameters for a PWM control signal, generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range, and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0009] In some examples, a method is of converting voltage is provided. The method includes: determining, by a control system, PWM operational parameters for a PWM control signal for controlling a variable-frequency power converter, wherein the variable-frequency power converter includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, an LC filter comprising a filter inductor and a filter capacitor, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element; generating, by the control system, a PWM control signal modification to the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and controlling, by the control system, the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0010] In some examples, a non-transitory computer readable medium including instructions stored thereon is provided. The instructions, when executed by a computer, control a-3-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 computer to: determine PWM operational parameters for a PWM control signal for controlling a variable-frequency power converter, wherein the variable-frequency power converter includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, an LC filter comprising a filter inductor and a filter capacitor, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element; generate a PWM control signal modification to the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0011] The foregoing and other aspects and advantages of the present disclosure will appear from the following description. In the description, reference is made to the accompanying drawings that form a part hereof, and in which there is shown by way of illustration one or more embodiment. These embodiments do not necessarily represent the full scope of the invention, however, and reference is therefore made to the claims and herein for interpreting the scope of the invention. Like reference numerals will be used to refer to like parts from Figure to Figure in the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 illustrates a power converter system, according to some embodiments.

[0013] FIG. 2 illustrates a converter system, which is an example of the power converter system of FIG. 1, according to some embodiments.

[0014] FIG. 3 illustrates the converter system of FIG. 2 with parasitic elements, according to some embodiments.

[0015] FIG. 4 illustrates another converter system, which is another example of the power converter system of FIG. 1, according to some embodiments.

[0016] FIG. 5 illustrates another converter system, which is another example of the power converter system of FIG. 1, according to some embodiments.

[0017] FIG. 6 illustrates a three-phase converter system, which is another example of the power converter system of FIG. 1, according to some embodiments.-4-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0018] FIG. 7 illustrates a three-phase electromagnetic interference (EMI) filter for the three-phase converter system of FIG. 6, according to some embodiments.

[0019] FIG. 8 illustrates a process for operating a power converter, according to some embodiments.

[0020] FIG. 9 illustrates a control system for controlling a power converter, according to some embodiments.

[0021] FIG. 10 illustrates an example converter circuit that may be used for simulation, according to some embodiments.

[0022] FIG. 11 illustrates a process for characterizing EMI and designing an EMI filter for a power converter, according to some embodiments.

[0023] FIG. 12A illustrates an example voltage waveform for DC-AC operation of the converter circuit of FIG. 10, according to some embodiments.

[0024] FIG. 12B illustrates an example grid of setpoints for operation of the converter circuit of FIG. 10, according to some embodiments.

[0025] FIG. 13 illustrates an example EMI versus frequency data plots for the power converter of FIG. 10, according to some embodiments.

[0026] FIG. 14 illustrates a heatmap of attenuation for EMI peaks at various setpoints for a first range of EMI frequencies of the power converter of FIG. 10, according to some embodiments.

[0027] FIG. 15A-15B illustrates a heatmap of attenuation for EMI peaks at various setpoints for a second and third range of EMI frequencies for the power converter of FIG. 10, according to some embodiments.

[0028] FIG. 16A illustrates a cutoff frequency heatmap for the first range of EMI frequencies of the power converter of FIG. 10, according to some embodiments.

[0029] FIG. 16B illustrates an LC product heatmap for the first range of EMI frequencies of the power converter of FIG. 10, according to some embodiments.

[0030] FIGS. 17A-17B illustrate plots with frequency data resulting from current sweeps at duty cycle 0.4 and 0.9 for the power converter of FIG. 10, according to some embodiments.

[0031] FIG. 18A illustrates a PWM control signal for controlling power switching elements of a power converter, according to some embodiments.-5-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0032] FIGS. 18B, 18C, and 18D illustrate modified PWM control signals with jitter for controlling power switching elements of a power converter, according to some embodiments.

[0033] FIG. 19 illustrates modified PWM control signals with a switching frequency offset for controlling power switching elements of a power converter, according to some embodiments.

[0034] FIG. 20 illustrates a process for operating a power converter using selective application of a PWM control signal modification, according to some embodiments.

[0035] FIG. 21 illustrates examples of leakage current versus frequency data plots for a power converter, according to some embodiments.

[0036] FIG. 22 illustrates an example of a computer system in accordance with various aspects of the present disclosure.DETAILED DESCRIPTION

[0037] One or more embodiments are described and illustrated in the following description and accompanying drawings. These embodiments are not limited to the specific details provided herein and may be modified in various ways. Furthermore, other embodiments may exist that are not described herein. Also, functions performed by multiple components may be consolidated and performed by a single component. Similarly, the functions described herein as being performed by one component may be performed by multiple components in a distributed manner. Additionally, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

[0038] As used in the present application, “non-transitory computer-readable medium” comprises all computer-readable media but does not consist of a transitory, propagating signal. Accordingly, non-transitory computer-readable medium may include, for example, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a RAM (Random Access Memory), register memory, a processor cache, or any combination thereof.

[0039] In addition, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. For example, the use of “comprising,” “including,” “containing,” “having,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Additionally, the terms-6-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303“connected” and “coupled” are used broadly and encompass both direct and indirect connecting and coupling, and may refer to physical or electrical connections or couplings. Furthermore, the phase "and / or" used with two or more items is intended to refer to these items individually and together. For example, “a and / or b" is intended to mean: a (and not b); b (and not a); and a and b.

[0040] Electrical circuits of power converters, also referred to as voltage converters, may be subject to electromagnetic interference (EMI). EMI is generally not desired within a power converter and can be challenging to reduce or eliminate. For example, EMI can be challenging to mitigate because EMI can be caused by a variety of both internal and external sources and can present in various forms. Internal sources of EMI may include, for example, switching of power switching elements of the power converter and / or control signaling that drives the power switching of power switching elements. External sources of EMI may include, for example, other nearby electrical equipment emitting (intentional) radio waves or (unintentional) electromagnetic signals, as well as noise propagating through or generated by connected electrical circuits (e.g., an alternating current (AC) grid providing or receiving power from the power converter). When not managed, EMI can cause electronics of a power converter to operate poorly, malfunction, or stop working entirely and / or can cause interference with other nearby electronics. Further, EMI may cause leakage current within electrical circuits of power converter. Leakage current in a power converter is an unintended or undesirable flow of current to ground or other conductors (e.g., through parasitic capacitance or “y’ capacitors). For example, conducted EMI (in contrast to radiated EMI), may cause or contribute to such leakage currents, where the leakage currents are a function of conducted EMI. This conducted EMI that causes or contributes leakage currents may occur at a lower frequencies than frequencies that may be traditionally associated with EMI (e.g., at frequencies lower than 150 kHz). Further, EMI at certain frequencies may correspond to higher leakage currents than other frequencies.

[0041] To mitigate EMI, additional filter components may be added to a power converter, but such additional filter components may increase the size, increase the cost, reduce the efficiency, and / or reduce the power density of a power converter unnecessarily when not carefully designed. It can be desirable to minimize the size of such additional EMI filter hardware while still mitigating EMI to acceptable levels. Increased switching frequencies and variable switching frequencies in power converters can provide benefits (e.g., an increase in power conversion efficiency), but can also provide additional challenges for EMI mitigation. For example, because-7-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303EMI can vary with switching frequencies, peak EMT for a variable-frequency power converter does not necessarily correspond to peak power output of a power converter. Accordingly, identifying an EMI mitigation strategy that will be effective, while not overly increasing a size or cost of a converter, can be difficult, particularly early in a converter design stage.

[0042] Some embodiments described herein address these and / or other issues. For example, some embodiments described herein provide additional hardware or circuit components (e.g., capacitors, inductors, etc.) forming EMI filters in power converter topologies to reduce or mitigate EMI. Further, some embodiments described herein provide techniques for designing EMI filters that are effective while not being over-sized. In addition or instead of additional hardware or circuit components, some embodiments described herein provide additional control techniques for power converters to reduce or mitigate EMI. By reducing the EMI, the additional control techniques may also reduce leakage currents that may otherwise arise from the EMI.

[0043] Accordingly, disclosed herein are systems, methods, and media related to EMI mitigation for power converters.

[0044] FIG. 1 illustrates a power converter system 100 in accordance with some embodiments. The power converter system 100 includes a control system 105, a DC load / source 110, a DC-side EMI filter 112, a power converter 115, a switch-side EMI filter 118, a second source / load 130, one or more sensors 140, and an input-output (I / O) interface. The control system 105 includes a central controller 150 with an electronic processor 155 and a memory 157, and, optionally, in some embodiments, includes one or more local controllers 160, each having an electronic processor 165 and a memory 167. The power converter system 100, as well as the other power converter systems provided herein, may be non-isolated power converter systems. That is, the power converter system may be coupled to an AC source (e.g., single- or three-phase power grid) or AC load (e.g., single or 3-phase motor) without a transformer. Use of a transformer is common in electrical circuits to provide isolation between the power converter and an AC source or load. However, such a transformer can add inefficiencies and size or volume to the power converter. Accordingly, power converter systems provided herein may be non-isolated, also referred to as transformerless, to increase efficiency and / or reduce size of the power converter systems. Because such power converters are provided without isolation by a transformer, the power converters may include additional features to prevent transmission of unwanted signals or current (e.g., leakage current) from passing between the power converters and other circuit-8-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 components (e.g., DC sources, DC loads, AC sources, AC loads, and other structures in contact with or supporting the power converters). These additional features may include LC filters for each bridge circuit, active control of common mode voltage and / or current, active control of DC bus voltage of a power converter, and the like. In some examples, however, a transformer may be included (e.g., between the switch-side EMI filter 118 and second source / load 130) to provide an isolated power converter in which the power converter 115 is coupled to an AC source or load via a transformer.

[0045] In operation, generally, the control system 105 controls power switching elements of the power converter 115 with control signaling (e.g., pulse-width modulated (PWM) signals) to convert power (i) from the DC load / source 110 functioning as a source to the second source / load 130 functioning as a load, or (ii) from the second source / load 130 functioning as a source to the DC load / source 110 functioning as a load. Accordingly, when the DC load / source 110 is functioning as a source for the power converter 115, the second source / load 130 is functioning as a load for the power converter 115. Conversely, when the DC load / source 110 is functioning as a load for the power converter 115, the second source / load 130 is functioning as a source for the power converter 115.

[0046] The DC load / source 110 may be a direct power (DC) load, a DC source, or both a DC load and DC source (i.e., functioning as DC source in some instances and as a DC load in other instances, depending on the mode of the power converter 115). In some examples, the DC load / source 110 is a battery including one or more battery cells (e.g., an electric vehicle battery or backup power battery). In other examples, DC load / source 110 may be a capacitor, an ultracapacitor, a DC power supply from rectified AC source (e.g., AC grid power converted to DC power by diode bridge rectifier), or the like. The second source / load 130 may be an AC load, an AC source, both an AC load and AC source (i.e., functioning as an AC source in some instances and as an AC load in other instances, depending on the mode of the power converter 115). In some examples, the second source / load 130 may be an electric (AC) motor, an AC generator, AC power supply grid, or the like. In some examples, such as where the power converter 115 is a DC / DC converter, the second source / load 130 is a DC load, a DC source, or both a DC load and a DC source (i.e., functioning as DC source in some instances and as a DC load in other instances, depending on the mode of the power converter 115).-9-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303

[0047] The DC load / source 110 is coupled to the power converter 115 at a first (DC) side or section of the power converter 115, and the second source / load 130 is coupled to the power converter 115 at a second side or section of the power converter 115. The first side may also be referred to as an input side or an output side of the power converter 115, depending on the mode of the power converter, or as a DC side of the power converter 115. The second side may also be referred to as an input side or an output side of the power converter, depending on the mode of the power converter, or as an AC side, second DC side, or switch-side side of the power converter 115. In some embodiments, the second side of the power converter 115 may be an AC side having single-phase AC power, three-phase AC power, or AC power with another number of phases.

[0048] In some embodiments, the power converter 115 operates with a high DC voltage level. For example, in operation, the DC side of the power converter 115 has a DC voltage (e.g., across input terminals of the power converter 115) of at least 200 V, at least 600 V, at least 800 V, at least 1000 V, at least 1200 V, between 200 V and 1200 V, between 600 V and 1200 V, between 800 V and 1200 V, or another range. Such high DC voltage levels may be desirable in some contexts, such as some electric vehicles. For example, some current electric vehicles (e.g., passenger vehicles and hybrid electric vehicles) operate with a DC bus voltage of between about 200 V and 400 V. This DC bus voltage for passenger electric vehicle may increase in the future. Further, some current electric vehicles (e.g., class 4-8, off-road, or otherwise larger electric vehicles) can operate with a DC bus voltage of more than 1000 V. However, high DC voltage levels may introduce challenges into a typical power converter system, such as an increase in leakage currents, increases in common mode voltage, higher rates of change in common mode voltage, and the like. These challenges can lead to resonance on LC filters, shaft voltages, excessive bearing currents (e.g., from discharge events when lubricant dielectric breakdown occurs) that can result in bearing failures, excessive motor shaft currents, excessive motor winding currents (e.g., insulation may be damaged), and excessive geartrain currents (e.g., bearing currents can propagate into the gear train via electromagnetic interference (EMI) or noise, vibration, harshness (NVH) resulting from the damaged bearing race walls). Embodiments described herein, however, can mitigate such challenges through LC filters and control techniques described herein.

[0049] The power converter 115 includes a DC link capacitor 170, power switching elements 175, and an LC filter 180. The DC link capacitor 170 may be connected across positive-10-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 and negative DC nodes of a DC bus connected to the DC-side EMI fdter 112. The DC link capacitor 170 can smooth out DC voltage on the DC bus.

[0050] The power switching elements 175 may be, for example, be field effect transistors (FETs), each having a respective gate, source, and drain terminal. The FETs may be, for example, a MOSFET, a silicon carbide (SiC) FET, a gallium nitride (GaN) FET, among other types of FETs. The power switching elements 175 may be controlled by control signaling (e.g., pulse-width modified (PWM) signals) from the control system 105 to convert power (e.g., from DC to DC, DC to AC, or AC to DC). The power switching elements 175 may be arranged in one or more halfbridge circuits, each half-bridge circuit including a pair of power switching elements (e.g., an upper and lower switch connected at a midpoint node) and an LC filter of the LC filter 180.

[0051] The LC filter 180 may include one or more LC filters. For example, the LC filter 180 may include an LC filter for each phase, each phase leg, and / or each half-bridge circuit of the power converter 115. Each LC filter may include at least an inductor and a capacitor, or at least an inductor and two capacitors, as illustrated in further detail, for example, in FIGS. 2 and 6 (see, e.g., LC filters with LC filter inductor 213, LC filter lower capacitor 214, and LC filter upper capacitor 217), and in FIGS. 3, 4, 5, and 10 (see, e.g., LC filters with an inductor and lower capacitor).

[0052] The DC-side EMI filter 112 is coupled between the DC load / source 110 and the power converter 115, and, more particularly, between the DC load / source 110 and the DC link capacitor 170. As described in further detail below, the DC-side EMI filter 112 includes one or more circuit elements (e.g., capacitors and / or inductors) arranged to provide EMI filtering. A plurality of examples of different arrangements of the DC-side EMI filter 112 are illustrated and described herein. In some examples, the DC-side EMI filter 112 may be a second order filter.

[0053] The switch-side EMI filter 118 is coupled between the second source / load 130 and the power converter 115, and, more particularly, between the second source / load 130 and the LC filter 180. As described in further detail below, the switch-side EMI filter 118 includes one or more circuit elements (e.g., capacitors and / or inductors) arranged to provide EMI filtering. A plurality of examples of different arrangements of the switch-side EMI filter 118 are illustrated and described herein. In some examples, the switch-side EMI filter 118 may be a second order filter.

[0054] As illustrated in FIG. 1, the power converter system 100 may include both the DC- side EMI filter 112 and the switch-side Emi filter 118. However, in some examples of the system 100, the DC-side EMI filter 112 is present, but the switch-side EMI filter 118 is not present.-11-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303Similarly, in some examples of the system 100, the switch-side EMT filter 118 is present, but the DC-side EMI filter 112 is not present. Similarly, although the power converter systems of FIGS. 2-5 are illustrated with both a DC-side and switch-side EMI filter, in some examples, one or more of these power converter systems may include a DC-side EMI filter or a switch-side EMI filter, rather than both EMI filters.

[0055] The sensor(s) 140 include, for example, one or more current sensors and / or one or more voltage sensors. For example, the sensor(s) 140 may include a respective current sensor and / or voltage sensor to monitor a current and / or voltage of one or more of the DC load / source 110, each phase or phase leg of the second source / load 130, each phase of the LC filter 180, or other nodes or components of the power converter 115. For example, when the LC filter 180 is a three-leg LC filter, the sensors 140 may include at least three current sensors, one for sensing current at each leg of a three-leg LC filter 180. In some embodiments, additional or fewer sensors 140 are included in the power converter system 100. For example, the sensors 140 may also include one or more vibration sensors, temperature sensors, and the like. In some examples, the control system 105 infers a characteristic (e.g., current or voltage) of the power converter 115, rather than directly sensing the characteristic. The sensor(s) 140 may provide sensor data to the control system 105 indicative of the sensed characteristics of the power converter system 100. Such sensor data may, accordingly, indicate electrical operational characteristics of the power converter system 100. In some examples, the control system 105 infers or estimates a characteristic (e.g., current or voltage) at one or more nodes of the power converter 115 based on the sensor data of a sensor of sensors 140 that senses a different type of characteristic or even a different component, rather than directly sensing the characteristic.

[0056] The input-output (I / O) interface 142 includes or is configured to receive input from one or more inputs (e.g., one or more buttons, switches, touch screen, keyboard, and the like), and / or includes or is configured to provide output to one or more outputs (e.g., LEDs, display screen, speakers, tactile generator, and the like). Other electronic devices and / or users may communicate with the power converter system 100 and, in particular, the control system 105, via the I / O interface 142. For example, the control system 105 may receive commands (e g., from a user or another device) for the power converter system 100 indicating a target torque, target speed, target power level, conversion type, or the like. The control system 105, in response, may drive the power converter 115 to achieve the target and / or conversion type indicated by the command.-12-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0057] The control system 105 generally monitors the power converter system 100 including the power converter 115 (e.g., based on sensor data from the sensor(s) 140), receives commands (e.g., via the I / O interface 142 or a memory 157, 167), and controls the power switching elements 175 of the power converter 115 with control signaling (e.g., pulse-width modulated (PWM) signals) to convert power (e.g., in accordance with the sensor data and / or the commands). In some embodiments, the control system 105 includes a controller (e.g., the central controller 150) that performs this monitoring and control without additional local controllers. In other embodiments, the control system 105 is a cascaded control system including a central controller 150 and one or more local controllers 160. The cascaded control system may communicate in real time (e.g., each control cycle) monitoring information (e.g., sensor data) and control information between the central controller 150 and the one or more local controller 160. In some examples, the local controller(s) 160 each implement model predictive control (MPC) or another regulation control scheme (e.g., PID control, PI control, or the like). In some examples, the central controller implements a non-MPC regulation technique, such as proportional integral derivative (PID) control or proportional integral (PI) control.

[0058] Each controller of the control system 105, including the central controller 150 and the local controllers 160, is an electronic controller that may include an electronic processor. Such an electronic controller may further include a memory (e.g., the memory 157 or 167). The memory is, for example, one or more of a read only memory (ROM), random access memory (RAM), or other non-transitory computer-readable media. The electronic processor 155, 165 is configured to, among other things, receive instructions and data from the memory 157, 167 and execute the instructions to, for example, carry out the functionality of the associated controller described herein, including the processes described herein. For example, the memory may include control software. In some embodiments, instead of or in addition to executing software from the memory to carry out the functionality of the controller described herein, the electronic processor includes one or more hardware circuit elements configured to perform some or all of this functionality. For example, the electronic processor 155, 166 may be or include an application specific integrated circuit (ASIC) or field programmable gate array (FPGA). Additionally, although a particular controller, electronic processor, and memory may be referred to as a respective, single unit herein, in some embodiments, one or more of these components is a distributed component. For example, in some embodiments, an electronic processor includes one or more microprocessors and / or-13-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 hardware circuit elements. The electronic processor(s) as described herein, including the electronic processors 155, 166, may also be referred to as processing unit(s).

[0059] FIGS. 2 to 6 illustrate respective examples of the power converter system 100. More particularly, FIGS. 2 to 6 illustrate examples of the power converter 115, DC-side EMI fdter 112, and switch-side EMI filter 118 of examples of the power converter system 100. The other elements of the power converter system 100 (e.g., the control system 105, the DC load / source 110, the second source / load 130 (except for FIG. 6), the sensors 140, and the I / O interface 142) are not illustrated to simplify the drawings. However, these other elements may be present in one or more of these examples. Between these FIGS. 1-5, and other figures herein, like reference numbers are used for like components, unless otherwise noted.

[0060] FIG. 2 illustrates a converter system 200, which, as noted, is an example of the power converter system 100, according to some embodiments. The converter system 200 includes a DC-side EMI filter 212, which is an example of the DC-side EMI filter 112 of FIG. 1, power converter 215, which is an example of the power converter 115 of FIG. 1, and a switch-side EMI filter 218, which is an example of the switch-side EMI filter 118 of FIG. 1. The power converter 215 further includes the DC link capacitor 170, a half-bridge circuit 205 including the power switching elements 175 and the LC filter 180. The power switching elements 175 include an upper switch 210 and a lower switch 211. The LC filter 180 includes an LC filter inductor 213, a lower LC filter capacitor 214, and an upper LC filter capacitor 217. The half-bridge circuit 205 further includes a drain-source capacitor 216 across each drain and source of each of the power switching elements 175. In some examples, the upper LC filter capacitor 217 and / or the drain-source capacitor 216 are not present.

[0061] The half-bridge circuit 205 includes a DC voltage section 220 including a DC bus 222 with a positive DC node 224a and a negative DC node 224b (also referred to collectively as DC nodes 224). The half-bridge circuit 205 further includes a switch-side section 225 including connection nodes 226a and 226b (also referred to collectively as connection nodes 226). The halfbridge circuit 205 further includes a midpoint node 230 connecting the upper and lower switches 210 and 21 1 . More particularly, the midpoint node 230 connects a drain terminal of upper switch 210 and a source terminal of lower switch 211.

[0062] The LC filter inductor 213 is coupled between the midpoint node 230 and a filter node 232. For example, a first end of the LC filter inductor 213 is coupled to the midpoint node-14-QB\ 175073.00303\98524560.2Attomey Docket No.: 175073.00303230, and a second end is coupled to the filter node 232. The lower capacitor 214 is coupled between the filter node 232 and the negative DC node 224b. For example, a first end of the lower capacitor 214 is coupled to the filter node 232, and a second end is coupled to the negative DC node 224b. The upper capacitor 217 is coupled between the filter node 232 and the positive DC node 224a. For example, a first end of the upper capacitor 217 is coupled to the filter node 232, and a second end is coupled to the positive DC node 224a.

[0063] The DC-side EMI filter 212 is connected across the DC bus 222 and, more particularly, is connected to the positive and negative DC nodes 224a, 224b. The DC-side EMI filter 212 includes a first EMI inductor 240, a second EMI inductor 242, a first capacitor 244, a second capacitor 246, and a ground node 248. The DC-side EMI filter 212 further includes a positive DC EMI node 250 and a negative DC EMI node 252, collectively a DC EMI bus, for connecting to a DC source / load (see, e.g., the DC load / source 110 of FIG. 1). For example, the positive DC EMI node 250 may be connected to a positive terminal of a battery (as the DC load / source 110) and the negative DC EMI node 252 may be connected to a negative terminal of the battery. The first EMI inductor 240 is connected to and between the positive DC node 224a and the positive DC EMI node 250. The second EMI inductor 242 is connected to and between the negative DC node 224b and to the negative DC EMI node 252. The first capacitor 244 is connected to and between the positive DC EMI node 250 and the ground node 248. The second capacitor 246 is connected to and between the negative DC EMI node 252 and the ground node 248. As shown in FIG. 2, the positive DC EMI node 250 is connected to both the first capacitor 244 and the first EMI inductor 240 (e.g., the positive DC EMI node 250 connects the first capacitor 244 to the first EMI inductor 240). Similarly, the negative DC EMI node 252 is connected to both the second capacitor 246 and the second EMI inductor 242 (e.g., the negative DC EMI node 252 connects the second capacitor 246 to the second EMI inductor 242).

[0064] The switch-side EMI filter 218 is connected across the connection nodes 226 and, more particularly, is connected to the connection nodes 226a, 226b. The switch-side EMI filter 218 includes a first EMI inductor 260, a second EMI inductor 262, a first capacitor 264, a second capacitor 266, and a ground node 268. The switch-side EMI filter 218 further includes a switchside EMI node 270 and a switch-side EMI node 272, collectively a switch-side EMI bus, for connecting to a second load / source (see, e.g., the second source / load 130 of FIG. 1). The first EMI inductor 260 is connected to and between the connection node 226a and the switch-side EMI node-15-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303270. The second EMT inductor 242 is connected to and between the connection node 226b and to the switch-side EMI node 272. The first capacitor 264 is connected to and between the switch-side node 270 and the ground node 268. The second capacitor 266 is connected to and between the switch-side EMI node 272 and the ground node 268.

[0065] Each of the components of the switch-side EMI filter 218 may also be referred to as switch-side EMI components (e.g., the first capacitor 264 may also be referred to as the first switch-side EMI capacitor 264) to further distinguish from the components of the DC-side EMI filter 212, which may also be referred to as DC-side EMI components (e.g., the first capacitor 244 may also be referred to as the first DC-side EMI capacitor 244).

[0066] FIG. 3 also illustrates the converter system 200, according to some examples. Whereas FIG. 2 illustrates intentional (discrete) circuit components (e.g., resistors, capacitors, inductor) of the converter system 200, FIG. 3 illustrates both intentional (discrete) circuit components and parasitic circuit components. Additionally, in FIG. 3, the upper capacitor 217 of the LC filter 180 is not included, and an additional gate resistor and gate voltage (representing a control signal source) for each of the switches 210 and 211 are illustrated. However, the upper capacitor 217 is present in some examples. In FIG. 3, parasitic components of the converter system 200 are identified as parasitic components 375.

[0067] FIG. 4 illustrates a converter system 400, which, as noted, is an example of the power converter system 100, according to some embodiments. The converter system 400 is similar to the converter system 200, except that the converter system 400 includes a different arrangement for the DC-side EMI filter 112. In particular, the converter system 400 includes a DC-side EMI filter 412 as the DC-side EMI filter 112 of FIG. 1. Otherwise, like elements are labeled with like numbers, and components of the half-bridge circuit 205 and the switch-side EMI filter 218 that are (generally) not individually labeled to simplify the drawing, except for some parasitic components 375. Additionally, some parasitic components 375 shown in FIG. 3 are not illustrated in FIG. 4, but may be present in the converter system 400.

[0068] Turning to the DC-side EMI filter 412, the DC-side EMI filter 412 is similar to the DC-side EMI filter 212 of FIGS. 2-3 except for the addition of an EMI capacitor 420 and a common mode inductor 422. The EMI capacitor 420 is coupled between and to (i) a first node 424 that joins the first EMI inductor 240 and a first leg 426 of the common mode inductor 422 and (ii) a second node 428 that joins the second EMI inductor 242 and a second leg 430 of the common-16-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 mode inductor 422. The first and second EMI inductors 240 and 242 may filter differential mode noise and EMI on the DC bus 222. The first and second EMI inductors 240 and 242 may also be referred to as differential mode inductors, or DC-side EMI differential mode inductors. The common mode inductor 422 includes the first leg 426 and the second leg 430. The first leg 426 may include a first coil wrapped around a magnetic core and connected between the first node 424 and the positive DC EMI node 250. The second leg 430 may include a second coil wrapped around the same magnetic core and connected between the second node 428 and the negative DC EMI node 252. The common mode inductor 422 may filter common mode noise and EMI on the DC bus 222.

[0069] Like in the DC-side EMI filter 212, the first capacitor 244 may be connected to and between the positive DC EMI node 250 and the ground node 248, and the second capacitor 246 may be connected to and between the negative DC EMI node 252 and the ground node 248. However, in the DC-side EMI filter 412, the first capacitor 244 and the positive DC EMI node 250 are further connected to the first leg 426 of the common mode inductor 422 (at an opposite end of the first leg 426 as the first node 424). Additionally, the second capacitor 246 and the negative DC EMI node 252 are further connected to the second leg 430 of the common mode inductor 422 (at an opposite end of the second leg 430 as the second node 428).

[0070] FIG. 5 illustrates a converter system 500, which, as noted, is an example of the power converter system 100, according to some embodiments. The converter system 500 is similar to the converter system 400, except that the converter system 500 includes a different arrangement for the DC-side EMI filter 112. In particular, the converter system 500 includes a DC-side EMI filter 512 as the DC-side EMI filter 112 of FIG. 1. Otherwise, like elements are labeled with like numbers, and components of the half-bridge circuit 205 and the switch-side EMI filter 218 that are not individually labeled to simplify the drawing, except for some parasitic components 375. Additionally, some parasitic components 375 shown in FIG. 3 are not illustrated in FIG. 5, but may be present in the converter system 500.

[0071] Turning to the DC-side EMI filter 512, the DC-side EMI filter 512 is similar to the DC-side EMI filter 412 of FIG. 4 except that the second EMI inductor 242 is not included. Accordingly, the second node 428 is connected to the negative DC node 224b and, thus, to a negative node of both the EMI capacitor 420 and the DC link capacitor 170.-17-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303

[0072] Although FIGS. 2-5 illustrate examples of the power converter system 100 (e.g., the converter systems 200, 400, 500) a single half-bridge circuit 205 as the power converter 115, in some examples, the power converter 115 includes two or more half-bridge circuits 205. For example, the power converter 115 may include two or more half-bridge circuits 205 coupled in parallel, sharing the DC bus 222 and the connection nodes 226. For example, the positive DC node 224a of each of the two or more half-bridge circuits 205 may be connected together, the negative DC node 224b of each of the two or more half-bridge circuits 205 may be connected together, the connection node 226a of each of the two or more half-bridge circuits 205 may be connected together, and the connection node 226b of each of the two or more half-bridge circuits 205 may be connected together. Then, the DC-side EMI filter 112, 212 may be connected to the two or more half-bridge circuits 205 via the positive and negative DC nodes 224a, 224b as illustrated in FIG. 2, and / or the switch-side EMI filter 118, 218 may be connected to the two or more half-bridge circuits 205 via the connection nodes 226a, 226b.

[0073] In some examples, the power converter 115 of FIG. 1 may be referred to as an biphase power converter, where N is equal to or greater than 1. In some examples, the power converter 115 of FIG. 1 is implemented as a split-phase power converter. In a split-phase example, the power converter 115 may include two half-bridge circuits. In some examples, the power converter may be capable of operating in multiple operational modes. For example, the power converter may include hardware components to operate in a three-phase system (e.g., with three half-bridges as illustrated in FIG. 6). Then, the control system 105 may control the power converter 115 to selectively operate in, and switch between operating in, a three-phase mode (e.g., when connected to a three-phase system), a split-phase mode (e.g., when connected to a split-phase system), a single-phase mode (e.g., when coupled to a single phase system). Here, the three-phase, split-phase, or single-phase system may be a power grid or motor, for example. When in a singlephase mode, two of the three half-bridges may be idle, with one being active; when in a split-phase mode, one of the three half-bridges may be idle, with two being active; and when in a three-phase mode, each of the half-bridges may be active.

[0074] FIG. 6 illustrates a three-phase converter system 600 which, as noted, is an example of the power converter system 100, according to some embodiments. The converter system 600 includes the DC-side EMI filter 112 (see, e.g., FIGS. 1-5), a power converter 615, which is an example of the power converter 115 of FIG. 1, and a three-phase AC-side EMI filter 618, which-18-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 is an example of the switch-side EMT filter 118 of FIG. 1 . The power converter 615 further includes the DC link capacitor 170, three half-bridge circuits 605 including the power switching elements 175 and the LC filter 180. The power switching elements 175 include an upper switch 210 and a lower switch 211 for each phase. The LC filter 180 includes, for each phase, an LC filter inductor 213, a lower LC filter capacitor 214, and an upper LC filter capacitor 217. Stated another way, each half-bridge circuit of the three half-bridge circuits 605 includes an upper switch 210 and a lower switch 211 connected at a midpoint node 230, as well as includes an LC filter of the LC filter 180. The three half-bridge circuits 605 further includes a drain-source capacitor 216 across each drain and source of each of the power switching elements 175. Thus, each half-bridge circuit of the three half-bridge circuits 605 is similar to the half-bridge circuit 205 illustrated in FIG. 2. In some examples, the upper LC filter capacitor 217 and / or the drain-source capacitor 216 are not present.

[0075] In the system 600, the DC-side EMI filter 112 may be implemented as, for example, the DC-side EMI filter 212, 412, or 512 of FIGS. 2-5.

[0076] The three half-bridge circuits 605 includes a DC voltage section 620 including the DC bus 222 with the positive DC node 224a and the negative DC node 224b (also referred to collectively as the DC nodes 224). The three half-bridge circuits 605 further include a switch-side section 625 including connection nodes 626a., 626b, and 626c (also referred to collectively as connection nodes 626). The LC filter inductor 213 of each phase is connected between the midpoint node 230 and a filter node 232 for that phase. Additionally, the lower LC filter capacitor 214 of each phase is connected between the filter node 232 for that phase and the negative DC node 224b for that phase. Similarly, the upper LC filter capacitor 217 for each phase is connected between the filter node 232 for that phase and the positive DC node 224a.

[0077] The three-phase AC-side EMI filter 618 is connected to the connection nodes 226 and to a three-phase load / source 630, which is an example of the second source / load 130 of FIG. 1. The three-phase load / source 630 is illustrated as an AC grid; however, in some examples, the three-phase load / source 630 is a three-phase motor, a three-phase generator, or another three-phase device. An example of the three-phase AC-side EMI filter 618 is illustrated and described in further detail with respect to FIG. 7.

[0078] FIG. 7 illustrates an example of the three-phase AC-side EMI filter 618, which may be included in the converter system 600 of FIG. 6, in some examples. The three-phase AC-side-19-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303EMI filter 618, also referred to as the three-phase EMT filter 618 or the three-phase AC-side EMI filter 618, is coupled to an LC filter (e.g., the LC filter 180 of FIG. 6) via connection nodes 626 at one end, and to an AC load / source (e.g., the three-phase load / source 630) via EMI connection nodes 702a, 702b, and 702c (collectively EMI connection nodes 702) at another end.

[0079] The three-phase EMI filter 618 includes a first capacitive stage 704, a first inductive stage 706, a second capacitive stage 708, and a second inductive stage 710. The first capacitive stage 704 includes a first A-phase capacitor 712 connected to the first AC connection node 626a, a first B-phase capacitor 714 connected to the second AC connection node 626b, and a first C- phase capacitor 716 connected to the third AC connection node 626c. Each of the first A-phase, B-phase, and C-phase capacitors 712, 714, and 716 are each also connected to a first common node 718. Accordingly, the first A-phase, B-phase, and C-phase capacitors 712, 714, and 716 may also be described as being connected between the first common node 718 and the connection nodes 626a, 626b, and 626c, respectively.

[0080] The first inductive stage 706 includes a first A-phase inductor 722 connected at a first end to the first AC connection node 726a and the A-phase capacitor 712, a first B-phase inductor 724 connected to the second AC connection node 726b and the B-phase capacitor 714, and a first C-phase inductor 726 connected to the third AC connection node 726c and the C-phase capacitor 716.

[0081] The second capacitive stage 708 includes a second A-phase capacitor 732 connected to a second end of the first A-phase inductor 722, a second B-phase capacitor 734 connected to a second end of the first B-phase inductor 724, and a second C-phase capacitor 736 connected to a second end of the first C-phase inductor 726. The second capacitive stage 708 further includes a common capacitor 738 coupled between ground and a second common node 740. The second common node 740 connects the second A-phase, B-phase, and C-phase capacitors 732, 734, and 736 together.

[0082] The second inductive stage 710 includes a second A-phase inductor 742 connected at a first end to the first A-phase inductor 722 and to the second A-phase capacitor 732, a second B-phase inductor 744 connected at a first end to the first B-phase inductor 724 and to the second B-phase capacitor 734, and a second C-phase inductor 746 connected at a first end to the first C- phase inductor 726 and to the second C-phase capacitor 736. Each of the second A-phase, B-phase,-20-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 and C-phase inductors 742, 744, and 746 are coupled at respective second ends to the EMI connection nodes 702a, 702b, and 702c.

[0083] The three-phase EMI filter 618 includes intermediate nodes 748a, 748b, and 748c that provide, respectively, the connection between (i) the first A-phase, B-phase, and C-phase inductors 722, 724, and 726, (ii) the second A-phase, B-phase, and C-phase inductors 742, 744, and 746, and (iii) the second A-phase, B-phase, and C-phase capacitors 732, 734, and 736. Accordingly, the second A-phase, B-phase, and C-phase capacitors 732, 734, and 736 may also be described as being connected between the second common node 740 and the intermediate nodes 648a, 648b, and 648c, respectively.

[0084] In some examples, the EMI filters described herein may provide a safety feature as a secondary feature, in addition to providing EMI filtering. More particularly, the passive components each EMI filter may have a predetermined fault or failure point, which may be a maximum current or voltage the component may experience before shorting or creating an open circuit. The CY capacitors 244, 246, 264, and 266 (see, e.g., FIG. 2) may, upon experiencing excess current or voltage, fail and create a short to the ground node 248 or 268. Similarly, the CX capacitors 420 (see, e.g., FIG. 4) may, upon experiencing excess current or voltage, fail and create an open circuit preventing a short from positive to negative battery terminals.

[0085] FIG. 8 illustrates a process 800 for operating a power converter. The process 800 is described as being carried out by the power converter system 100 implemented as one of the converter systems 200, 400, 500, or 600. However, in some embodiments, the process 800 is implemented by another power converter system. Additionally, although the blocks of the process 800 are illustrated in a particular order, in some embodiments, one or more of the blocks may be executed partially or entirely in parallel, may be executed in a different order than illustrated in FIG. 8, or may be bypassed.

[0086] In block 805, a control system determines at least one electrical operational characteristic for a power converter, where the power converter includes a DC link capacitor connected across a DC bus, a half-bridge circuit including power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor. For example, with reference to FIG. 1, the control system 105, via the sensors 140, determines one or more voltages or currents of the power converter 115 (e.g., implemented as power converter 215 or 615 of FIGS. 2-6). With reference to FIG. 2, in some-21-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 examples, the at least one electrical operational characteristic may include one or more of an inductor current through the inductor 213, a capacitor voltage across lower capacitor 214, and / or a current through fdter node 232 to connection node 226a (sometimes referred as a grid current or motor current, depending on the type of the second source / load 130 connected to the converter 215). With reference to FIG. 6, in some examples, the at least one electrical operational characteristic may include, for each half-bridge circuit of the three half-bridge circuits 605, one or more of an inductor current through the inductor 213, a capacitor voltage across the lower capacitor 214, and / or a current through the fdter nodes 232 to connection nodes 226a.

[0087] In block 810, the control system determines a duty cycle and a switching frequency based on the at least one electrical operational characteristic. For example, the control system 105 may determine the duty cycle (D) and the switching frequency (Fsw), based on the at least one electrical operational characteristics, for controlling switching of the power switching elements 175 of the power converter 115. The control system 105 may serve as a regulator to control the overall operation and output of the power converter 115. For example, the control system 105 may receive a target parameter (e.g., output current or voltage) for the power converter 115 and may use the at least one electrical operational characteristic as a feedback value(s) to determine control signals to generate to control the power converter 115 to achieve or approach the target parameter. Further details of an example implementation of block 810 is provided with respect to FIG. 9 below.

[0088] In block 815, the control system drives the power switching elements of the halfbridge circuit with control signaling having the duty cycle and the switching frequency. For example, the control system 105 may generate and provide a pulse width modulated (PWM) control signal for each switch of the power switching elements 175. With reference to FIGS. 2-5, the PWM control signal for the upper switch 210 and the lower switch 211, provided by the control system 105 of FIG. 1, may have the duty cycle and switching frequency as determined in block 810. The PWM control signal for the upper switch 210 and for the lower switch 211 may be an inverse of one another (e.g., when the PWM control signal for the upper switch 210 is high or “ON”, the PWM control signal for the lower switch 211 is low or “OFF”). With reference to FIG. 6, the upper and lower switches 210, 211 for each respective half-bridge circuit of the three halfbridge circuits 606 may have a distinct duty cycle and switching frequency (e.g., as determined in block 810). In such cases, the control system 105 may generate and provide a first PWM control-22-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 signal for the upper and lower switches 210, 211 of phase A having a first duty cycle and switching frequency determined in block 810, a second PWM control signal for the upper and lower switches 210, 211 of phase B having a second duty cycle and switching frequency determined in block 810, and a third PWM control signal for the upper and lower switches 210, 211 of phase C having a third duty cycle and switching frequency determined in block 810. As with the single half-bridge circuit example, the PWM control signal to the upper and lower switches 210, 211 of each respective half-bridge may be the inverse of one another.

[0089] In block 820, an EMI fdter, connected across the DC bus or the connection nodes, filters power at the DC voltage section or at the switch-side connection of the power converter, where the EMI filter includes an EMI inductor, a first capacitor, and a second capacitor, and where the first and second capacitors are connected at a ground node. For example, with reference to FIGS. 1-6, the EMI filter 112, 212, 412, and / or 512 may be the EMI filter performing the filtering in block 820. For example, with reference to FIGS. 1-6, when the power converter 115, 215, and / or 615 is receiving DC power from the DC load / source 110 and converting the DC power to DC power at another voltage level or to AC power, the DC-side EMI filter 112, 212, 412, and / or 512 may perform filtering of the DC power received (e.g., at DC EMI nodes 250, 252) and output filtered DC power to the positive and negative DC nodes 224a, 224b for conversion by the power switching elements 175. As another example, with continued reference to FIGS. 1-6, when the power converter 115, 215, and / or 615 is receiving DC power or AC power from the second source / load 130 and / or 630 and converting the received power to DC power, the DC-side EMI filter 112, 212, 412, and / or 512 may perform filtering of the DC power received at the positive and negative DC nodes 224a, 224b, and output filtered DC power to the DC EMI nodes 250, 252.

[0090] Additionally, with reference to FIGS. 1-5, the EMI filter 118 may be the EMI filter performing the filtering in block 820. For example, with reference to FIGS. 1-6, when the power converter 115, 215, and / or 615 is receiving DC power from the DC load / source 110 and converting the DC power to DC power at another voltage level or to AC power, the switch-side EMI filter 118 may perform filtering of the DC or AC power received (e.g., at connection nodes 226) and output filtered DC or AC power to the nodes 270, 272. As another example, with continued reference to FIGS. 1-6, when the power converter 115, 215, and / or 615 is receiving DC power or AC power from the second source / load 130 and / or 630 and converting the received power to DC power, the switch-side EMI filter 118 may perform filtering of the DC or AC power received at-23-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 the nodes 270, 272, and output filtered DC or AC power to the connection nodes 226 for conversion by the power switching elements 175.

[0091] Additionally, in some examples, the process 800 includes additional filtering by a second EMI filter. For example, when the EMI filter performing the filtering in block 820 is the switch-side EMI filter 118, the second EMI filter performing filtering may be the DC-side EMI filter 112, 212, 412, and / or 512 of FIGS. 1-6. Similarly, when the EMI filter performing the filtering in block 820 is the DC-side EMI filter 112, 212, 412, and / or 512, the second EMI filter performing filtering may be the switch-side EMI filter 118 and / or 618 of FIGS. 1-6. When the second EMI filter is the EMI filter 618 of FIGS. 7, when the power converter 615 is receiving DC power from the DC load / source 110 and converting the DC power to three-phase AC power, the switch-side EMI filter 118 may perform filtering of the three-phase AC power received (e.g., at connection nodes 626) and output filtered three phase AC power to the nodes 702a, 702b, 702c. As another example, with continued reference to FIGS. 6-7, when the power converter 615 is receiving AC power from the second source / load 130 and / or 630 and converting the received power to DC power, the switch-side EMI filter 118 may perform filtering of the AC power received at the nodes 702a, 702b, 702c, and output filtered AC power to the connection nodes 626 for conversion by the power switching elements 175.

[0092] FIG. 9 illustrates a control system 900, which is an example of a portion of the control system 105 of the power converter system 100, according to some embodiments. More particularly, the control system 900 illustrates a portion of the control system 105 that may be used to control the power converter 115 (e.g., implemented as the power converter 215 or 615). For example, the control system 900, as illustrated, may be used for a three-phase converter such as, e.g., the power converter 615. In such examples, the control system 900 may include the central controller 150 and local sub-controllers 160a, 160b, and 160c, where the local sub-controllers 160a, 160b, and 160c may together be the local controller 160 for the three-phase converter. In this example, each local sub-controller 160a, 160b, and 160c is associated with a respective halfbridge circuit of the three half-bridge circuits 605 and, thus, a respective phase A, B, and C.

[0093] In another example, the control system 900 may be simplified when used for a converter with a single half-bridge circuit such as, e.g., the power converter 215. In such examples, the control system 900 may include the central controller 150 and the local sub-controller 160a, without the local sub-controllers 160b and 160c. As the other local sub-controllers 160b and 160c-24-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 are not present, the local sub-controller 160a may be referenced as the local controller 160. The central controller 150 and various local controllers 160 may be coupled via a communication bus 925.

[0094] As discussed above, the central controller 150 and various local controllers 160 may be implemented as physically separate devices by dedicated hardware or may include at least some virtual controllers implemented by shared hardware. Accordingly, the diagram in FIG. 900 may illustrate an architecture logically and / or physically, depending on the embodiment of the control system 105.

[0095] The central controller 150 and the local sub-controllers 160a-c may communicate with each other in real time (e.g., over the communication bus 925 in each control cycle) both monitoring information (e.g., sensor data) and control information. For example, the local subcontrollers 160a-c may determine (e.g., via sensors 140) and transmit to the central controller 150 electrical operational characteristics including one or more of Vg.abc, ig,abc, and ii .abc, and the central controller 150 may determine and transmit control reference targets (e.g., which may be vc.abc*, iuabc*, or ig,abc*) based on the received electrical operational characteristics. With reference to FIG. 6, Vg,abc may represent voltage across the lower capacitor 214 of each half-bridge circuit (e g., with Vg.a representing voltage across the lower capacitor 214 of phase a), ig.abc may represent current from the filter node 232 to the connection node 626 for each half-bridge (e.g., with ig,arepresenting current from the filter node 232 of phase a to connection node 626a), and iL,abc may represent current through the filter inductor 213 for each half-bridge (e.g., with ir.a representing current through the LC filter inductor 213 of phase a). The local sub-controllers 160a-c may further generate and transmit PWM control signals (PWMabc) to their corresponding half-bridge circuits based on the electrical operational characteristics and the control reference target for the particular half-bridge circuit. The PWM control signals output by the local sub -controllers 160a-c may indicate a duty cycle and / or a frequency for a PWM signal that drives a gate terminal of each power switching element of the corresponding half-bridge circuit, or may be the PWM signal itself. Each half-bridge circuit may further include a respective gate driver for driving the power switching elements of the half-bridge circuit, or the gate driver may be part of the corresponding local subcontrollers 160a-c.

[0096] In some embodiments of the control system 900, the central controller 150 provides an outer loop of control, while each of the local sub-controllers 160a-c provides a distinct inner-25-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 loop of control. For example, the central controller 150 may implement a proportional integral (PT) controller, proportional integral derivative (PID) controller, or other regulating controller that regulates conversion of a power converter (e.g., the converter 115, 215, 615) in a rotating reference frame (e.g., the dqO reference frame). The central controller 150 may receive the electrical operational characteristics (including one or more of Vg,abc, ig,abc, and iL,abc) in a stationary (abc) reference frame, transform the values to a rotational reference frame (e.g., the dqO reference frame using the Park and Clarke transforms), and generate a control reference target for each of the local sub-controllers 160a-c in the rotational reference frame (e.g., Refdqo). For example, based on one of the electrical operational characteristics (e.g., ig.dqo) and a target value for that characteristic (e.g., ig,dqo*), the central controller 150 may generate the control reference targets (e.g., Refdqo) using the regulating function (e.g., PI or PID control) to adjust or control the half-bridge circuits to achieve (or tend towards) the control reference target.

[0097] The central controller 150 may determine the target value for the characteristics (e.g., ig.dqo*) from an obtained command (e.g., obtained from a memory of the central controller 150 and / or received via the I / O interface 142). For example, the central controller 150 may translate the command (e.g., using a lookup table) to the target values for the characteristics. The central controller 150 may also translate the control reference targets (e.g., Refdqo) generated to the stationary reference frame using the inverse Park and Clark transforms and provide the control reference targets (e.g., targets Refa, Refb, Refc) to the local sub-controllers 160a-c. The control reference targets may be, for example, a reference capacitor voltage for the half-bridge circuits associated with the local sub-controllers receive the control reference target (e.g., vc,abc*). The reference capacitor voltage may be a target voltage to be across a lower capacitor of a half-bridge circuit (see, e.g., lower capacitor 214 of FIG. 3). Thus, as part of the outer loop of control, the central controller 150 generates control reference targets based on regulation in the rotating reference frame.

[0098] Each respective local sub-controller 160a-c implements the inner loop control via model predictive control (MPC), PI control, PID control, or another regulating technique, based on the control reference targets (e.g., target voltages to achieve operational parameters for the system, which can include a target velocity, acceleration, maximum heat flux, current, torque, etc.) received from the central controller 150. For example, each local sub-controller 160a-c may also receive a voltage measurement or estimate for the voltage across a lower capacitor (vc) (e.g., across-26-QB\175073.00303\98524560.2Attorney Docket No.: 175073.00303 lower capacitor 214 illustrated in FIGS. 2-6) associated with the same phase or half-bridge circuit as the local sub-controller. Based on the measured or estimated capacitor voltage (vc) and the control reference target (e.g., vc*), each local sub-controller 160a-c may control its associated halfbridge circuit to adjust or control the switching of the power switching elements to achieve (or tend towards) a capacitor voltage (vc) that is equal to the reference control target. The inner loop control provided by the respective local sub-controllers 160a-c includes the generation of control signaling provided to the half-bridge circuit (e.g., the PWM signals). The duty cycle of the PWM signal may be determined using a regulator scheme (e.g., PI, PID, or MPC algorithm) based on the control reference target received from the central controller 150 and estimated or measured values for the phase associated with the particular local sub-controller 160a-c. For example, generally, when the control reference target is higher than the estimated or measured value, the duty cycle may increase, and when the control reference target is lower than the estimated or measured value, the duty cycle may decrease. The particular amount of increase or decrease may be varied according to the regulator scheme.

[0099] The frequency may be selected using a variable-frequency soft- switching algorithm that identifies the frequency that will enable a soft switch of the power switching elements. By varying the switching frequency to achieve soft switching, as opposed to hard switching, high turnon losses of the upper switch are substituted with low turn-off losses of the lower switch of a halfbridge circuit. More particularly, in some examples, to realize soft switching, each local subcontroller 160a-c reshapes the phase leg inductor current ripple such that the vertex and nadir points are positive and negative. The vertex and nadir point ripple value should be large enough to guarantee a full soft switching. For example, each local controller 160a-c may receive or determine the inductor current (it), de rail voltage (vdc), and inductance of the inductor (Lf), and determined duty cycle, and determine from these inputs a switching frequency (fsw) to achieve soft switching for the half-bridge circuit that the local controller drives. The desired switching frequency (fsw) may be derived according to a threshold current, Ith, of soft-switching operation criteria. The phase leg side inductor current ripple, AiL, can be demonstrated asand the soft-switching operation criteria require the vertex and nadir points of the phase leg side inductor current values to be larger than Ithand smaller than -Ith. Thus, the derivation of the timevarying switching frequency, fsw, can be demonstrated asQB\ 175073.00303198524560.2Attorney Docket No.: 175073.00303in which iL ave represents the mean value of phase leg side inductor current.

[0100] When the control system 900 is used to control an example of the power converter 115 including a single phase and / or single half-bridge circuit, a similar procedure may be employed as described, with an outer loop of control provided by the central controller 150 and an inner loop of control provided by the local sub-controller 160a, but where the additional electrical characteristics, reference targets, PWM signals, and local sub-controllers 160b, 160c for the (not present) B and C phases may be not included. The local sub-controller 160a may, thus, perform the duty cycle and switching frequency determination for the half-bridge circuit 205 of the power converter 215, and may use the same principles as described above for a single phase of the three- phase power converter. Although the frequency may be determined to achieve soft-switching, as described above, in other examples, the frequency is selected without achieving or attempting to achieve soft switching.

[0101] EMI Filter Design

[0102] As noted above, power converters that employ variable-frequency switching (e.g., using variable-frequency PWM control signals) can enable soft-switching. Such power converters may be referred to as a variable-frequency power converters. For example, a power converter control system can employ a variable-frequency soft-switching algorithm that identifies the frequency that will enable a soft switch of the power switching elements. By varying the switching frequency to achieve soft switching, as opposed to hard switching, high turn-on losses of the upper switch are substituted with low turn-off losses of the lower switch of a half-bridge circuit. Thus variable-frequency power converters controlled to provide soft-switching (variable-frequency, soft-switching power converters) can provide power conversion with increased efficiency.

[0103] Variable-frequency power converters with variable-frequency PWM control signals can present new challenges for EMI mitigation. Considering electromagnetic compliance (EMC) early in a converter design process can provide benefits. However, EMI of a converter can be difficult to predict and EMI filter design is often an afterthought in the power electronics design process. The CISPR25 standard for electric vehicle conducted emissions specifies that, “When-28-QB\ 175073.00303\98524560.2Attomey Docket No.: 175073.00303 performing component / module tests, the equipment under test shall be made to operate under typical loading and other conditions as in the vehicle such that the maximum emission state occurs." Converters that operate with a constant frequency generally produce the maximum EMI emission at the greatest power output. Accordingly, with this understanding, maximum EMI emission for a converter can be determined through straight-forward testing and simulation, and corresponding EMI mitigation for such a converter to meet various EMI standards can be designed accordingly.

[0104] To design EMI mitigation techniques for variable-frequency, soft-switching converters to comply with the CISPR25 standard and other standards, it is also beneficial to determine an operational setpoint of the converter that results in maximum EMI emission. However, converters that operate with a variable frequency and soft switching are less predictable, and their maximum EMI emission does not necessarily correspond to the greatest power output of the converter. For example, variable-frequency, soft-switching converters may have harmonics that change in accordance with the switching frequency of the converter, and harmonics can shift in and out of the frequency ranges for electromagnetic compliance testing limits.

[0105] Techniques described herein enable proper characterization of the EMI of a variable-frequency, soft-switching converter for electromagnetic precompliance testing before designing the converter in hardware. For example, a half-bridge, dc-dc converter may be operated as a dc-ac inverter by changing both duty cycle and switching frequency to buck the bus voltage into a sinusoidal output. By operating the converter at many different duty cycle and frequency setpoints, EMI measurements for those setpoints can be determined and the setpoints can be identified that cause the greatest intensity EMI peaks beyond desired limits (e.g., of the CISPR25 2021 standard or other standards for conducted emissions). By identifying the maximum emission setpoint of the converter, an EMI filter can be designed that ensures compliance with the CISPR25 2021 conducted emission standards or other standards during operation.

[0106] FIG. 10 illustrates an example variable-frequency converter circuit 1000 that may be used for simulation with a process 1100 of FIG. 11 that is for characterizing EMI and designing an EMI filter for a converter. The variable-frequency converter circuit 1000 (also referred to as the converter circuit 1000) is similar to the converter 215 of FIGS. 2-5 and includes an EMI filter 1005 similar to the DC-side EMI filter 412 of FIG. 4. The converter circuit 1000 of FIG. 10 may be simulated using, for example, LTSpice or other commercially available simulation software. As-29-QB\ 175073.00303198524560.2Attorney Docket No.: 175073.00303 described further below, the converter circuit 1000 may be simulated in LTSpice over a 15 millisecond (ms) timescale without the EMI filter 1005 to gather EMI data used to characterize the EMI of the converter circuit 1000. When the EMI filter 1005 is not present, the terminals at VDCare connected directly across CDC. Parasitic elements 1010 of the converter circuit 1000 that are present in a hardware test setup are also shown in FIG. 10. The converter circuit 1000 includes LISN devices that were designed to the CISPR25 specification for conducted emissions measurement. In some examples, the MOSFETs in the half-bridge stage are modeled by the Wolfspeed C3M0021120K manufacturer-provided Spice model. Example circuit parameters for the converter circuit 1000 are shown in Table 1. Additional parasitics within the packaging and leads of the MOSFETs are not shown in FIG. 10 are present in the Wolfspeed model

[0107] Turning now to FIG. 11, the process 1100 for characterizing EMI and designing an EMI filter is illustrated. One or more blocks of the process 1100 may be carried out by a computer system. For example, a computer system including a memory (e g., a computer readable medium)-30-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 storing instructions and an electronic processor that retrieves and executes the instructions to implement blocks of the process 1100 (e.g., one or more of blocks 1105, 1110, and 1115). An example of such a computer system is a computer system 2200 illustrated in and described with respect to FIG. 22. Additionally, although the process 1100 is described with respect to the converter circuit 1000 of FIG. 10, in some examples, the process 1100 is executed with respect to another variable-frequency converter circuit, such as, for example, the converter 115, 215, and / or 615 of the one of the converter systems 100, 200, 400, 500, or 600, or another variable-frequency converter circuit. Additionally, although the blocks of the process 1100 are illustrated in a particular order, in some embodiments, one or more of the blocks may be executed partially or entirely in parallel, may be executed in a different order than illustrated in FIG. 11, or may be bypassed.

[0108] In block 1105, the process 1100 includes sweeping control signals that drive a variable-frequency converter circuit to drive the variable-frequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different combinations of duty cycles and switching frequencies. In some examples, the converter circuit and the driving thereof may be simulated using, for example, commercially available circuit simulation software (e.g., LTSpice). Accordingly, in some examples, in block 1105, sweeping control signals that drive the variablefrequency converter circuit includes sweeping control signals that drive the converter circuit 1000, in simulation. As also noted, in block 1 105, the EMI filter 1005 may not be present in the converter circuit 1000. In other examples, a physical (non-simulated) converter circuit may be driven in block 1105.

[0109] In some examples, to sweep the control signals in block 1105, the converter circuit 1000 is operated with a continuously variable frequency with an output filter inductor (Ly) current ripple and frequency relationship shown in equation 4. This equation guarantees soft switching by ensuring that iLis great enough to produce the desired average output current while satisfying soft- switching criteria. The constant of 2.4 in equation 5 ensures that the current will reach a negative enough level to guarantee soft switching at the upper MOSFET turn on when the CDScapacitors have drained. Output current ( / 0) of the variable-frequency converter circuit can vary continuously from 0 to 64 A. / Z(mching limit set to 8 A for the variable-frequency converter circuit, though this may vary for other designs.-31-QB\175073.00303\98524560.2Attorney Docket No.: 175073.00303F_ D(1-D)VDCZ4Jsw&iLLf>^i-L = 2.4( / 0+ / lim ) (5)

[0110] In equations 4 and 5, AiLis the difference between the peak and minimum inductor current ripple in Amperes, D is the duty cycle, VDCis the input voltage, fswis the PWM the switching frequency, and L is the output filter inductance value. The average output current can be changed by adjusting either the filter inductance Lf or the switching frequency, fsw. The two are inversely related; an increase in switching frequency results in a smaller filter inductor for the same current ripple. The average of the current ripple is the output current of the device, set by the constant current load, Io, in the LTSpice simulation parameters. The output of the half bridge of the converter circuit 1000 is filtered by an LC filter between the switching stage and the constant current load.

[0111] In block 1105, in some examples, the constant current load (Zo) may be varied in each simulation from 0 to 64 A in steps of 8 A. Each duty cycle from 0.1 to 0.9 for the PWM control of the gate drive voltages VG1may also be simulated at every current setpoint. In this example, the half-bridge of the converter circuit 1000 operates as a dc-dc buck converter for each simulation. An example voltage waveform of the dc-ac operation from 0.1 Vinto 0.97jnis presented in FIG. 12A by combining many dc-dc setpoints. An example of the simulations setpoints where EMI measurements are taken create a 9 x 9 grid, shown in Fig. 12B. In this example, the simulation setpoints used to create heatmaps occur at the vertices shown on this grid. The grid corresponds to the output at the ac side of the converter circuit 1010 at possible currents. The maximum power output occurs at a 0.9 duty cycle and 64 A load current. The steps in Fig 12B occur at points that are not locked to each 0.1 step in duty cycle. This permits the converter circuit 1000 to operate continuously in both duty cycle and output current in simulation. In hardware, the exact setpoints required to create a sinusoidal output can be predefined. However, in the interest of designing an output-agnostic EMC precompliance testing process, all continuous setpoints may be considered to be valid.

[0112] Also in block 1105, while sweeping the control signals in block 1105, electrical characteristic data may be captured. The electrical characteristic data may be indicative of EMI being produced by the variable-frequency converter circuit. For example, the electrical characteristic data may be a voltage waveform across the EMI measurement node and termination-32-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 node illustrated in FIG. 10. The electrical characteristic data may include, for example, simulated data waveforms captured using the simulation software (in the case of a simulated converter circuit) or data waveforms captured with sensors (in the case of using a physical converter circuit).

[0113] In block 1110, the process 1100 includes determining one or more setpoints of the control signals that result in peak EMI by the variable-frequency converter circuit. For example, the electrical characteristic data captured in block 1105 may be processed to determine the one or more setpoints resulting in peak EMI.

[0114] For example, the electrical characteristic data may include voltage data waveforms. The voltage data waveforms may be processed (e.g., in MATLAB or other signal processing software) to determine their frequency content. For example, the processing may include resampling irregularly sampled data (e.g., from LTSpice) and performing a fast Fourier transform (FFT) (e.g., in MATLAB) to generate frequency data. FIG. 13 illustrates an example of the frequency data in plot 1300. The frequency data and, ultimately, the peak EMI data may be organized into bins based on limits provided by a standard (e.g., the CISPR25 2021 standard) for high-voltage measurements in shielded power supply devices. An example of these frequency bins are shown numbered (1 through 7) in FIG. 13. In this example, Class 5 was used because it is the strictest class, that is, with the lowest limit values across all tested frequencies. The Class 5 limits and associated frequency bands are shown in Table 2. Though there are eight bands considered in the CISPR25 standard, some of them overlap. In some examples, passing the lowest limit in all ranges may be prioritized. Accordingly, in FIG. 13, seven bins are defined that range from 0.15- 0.30, 0.530-1.80, 5.9-6.2, 26-28, 30-41, 41-88, and 88-108 MHz. In other examples, other standards or classes of standards may be employed, which may be associated with different bins (frequency bands) and associated EMI peak limits.-33-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0115] Accordingly, for each setpoint of the range of setpoints of the control signals in block 1105, corresponding frequency data may have been captured. Further, this frequency data may be associated with bins of a standard (e.g., the seven bins noted above). Within each bin, a peak of the frequency data may be identified, which is an EMI peak in the for a setpoint in the range of setpoints. In some examples, when the frequency data contains a large data set (e.g., over a million points), the peaks of the frequency data may be analyzed and identified using a software function such as, for example, MATLAB’s findpeaks() function. The resulting identified peaks may be referred to as EMI peak data.

[0116] In some examples, the EMI peak data may be organized into a heatmap for each bin. FIG. 14 illustrates an example of such a heatmap, identified as heatmap 1400. The rectangles on the heatmap 1400 represent each of the 81 vertices of the grid in Fig. 12B and include EMI peak data for bin 1 (frequency range of 150 kHz to 300 kHz). In particular, for each setpoint, a highest peak was identified in the frequency range 150kHz - 300kHz, the value of the EMI limit for bin 1 (107 dBqV) plus 6 dB / zV was subtracted from this highest peak, and the resulting value is listed in the rectangle of the corresponding setpoint. Stated another way, each rectangle illustrates the EMI attenuation that would reduce the EMI to be 6 dBqV below the limit for bin 1. Rectangles grayed-out without data do not have a number (NaN) for display, indicating that no peaks in the frequency data at that setpoint surpass the limit in bin 1. Thus, no attenuation would be required for such setpoints with respect to bin 1. As illustrated in FIG. 14, the setpoint causing the highest EMI with respect to the bin 1 frequency range is the setpoint with duty cycle 0.6 and output current of 56 A.

[0117] A similar heatmap as the heatmap 1400 may be generated for each bin (e.g., for each of the seven bins). For example, FIG. 15A illustrates a heatmap 1500 of EMI peak data for bin 6, and FIG. 15B illustrates a heatmap 1505 of EMI peak data for bin 2. Accordingly, the setpoint resulting in the peak EMI for each bin may be determined. As shown in heatmap 1500, for bin 6, the setpoint resulting in the peak EMI has a duty cycle of 0.5 and an output current of 8-34-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303A. As shown in heatmap 1505, for bin 2, the setpoint resulting in the peak EMI has a duty cycle of 0.5 and an output current of 56 A.

[0118] Returning to FIG. 11, in block 1115, the process 1100 includes generating filter component values for an EMI filter based on the one or more setpoints of the control signals determined to result in peak EMI for the variable-frequency converter circuit. For example, a cutoff frequency and / or LC product for an EMI filter (e.g., the EMI filter 1005) to attenuate the peak EMI below applicable limits may be calculated for the one or more setpoints. For example, the cutoff frequency and / or LC product may be calculated for the setpoint resulting in the peak EMI for each bin, or for a subset of bins expected to require the most substantial or largest EMI filter components to attenuate the peak EMI to be below applicable limits. In some examples, the cutoff frequency and / or LC product may be calculated for each setpoint of each bin.

[0119] Equation 6 may be used to calculate the cutoff frequency(ies) (e.g., for the EMI filter to attenuate the maximum EMI peak of each bin). Then, equation 7 (an undamped LC filter transfer function may be solved using the determined cutoff frequency to calculate an LC product of the EMI filter for each desired setpoint to ensure sufficient attenuation to maintain the EMI below the applicable limits.

[0120] FIG. 16A illustrates a cutoff frequency heatmap 1600 for bin 1. In the cutoff frequency heatmap 1600, each rectangle again corresponds to one of the 81 setpoints of FIG. 12B. In some examples, a similar cutoff frequency heatmap may be generated for each bin. In other examples, as noted, a cutoff frequency may be calculated for a subset of setpoints. For example, a cutoff frequency may be calculated for the setpoint associated with the peak EMI for each bin.

[0121] FIG. 16B illustrates an LC product heatmap 1605 for bin 1. In the LC product heatmap 1505, each rectangle again corresponds to one of the 81 setpoints of FIG. 12B. In some examples, a similar LC product heatmap may be generated for each bin. In other examples, an LC product may be calculated for a subset of setpoints. For example, an LC product may be calculated for the setpoint associated with the peak EMI for each bin.

[0122] The determined LC products may be used to determine filter component values for an EMI filter. For example, the setpoint across all bins having the highest LC product may be used-35-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 to design an EMI filter to attenuate worst case EMT to be below applicable limits. By using the highest LC product, the resulting EMI filter can be expected to attenuate EMI across all bins to be below applicable limits. For example, as shown in the LC product heatmap 1505, the greatest LC value for bin 1 was 6.89 X 10-12s2. Keeping in mind the possibility that the maximum emission setpoint may not lie exactly at the grid vertex of the 0.6 duty cycle and 56 A output current, the LC product may be increased by an offset, for example, to 7.05 X 10-12s2. In addition to providing some cushion for variations in EMI near the vertex, by adding an offset, common values for the inductors and capacitors may be selected for the EMI filter.

[0123] With the adjusted LC product of 7.05 x 1012s2identified, components of the EMI filter may be selected. For example, with reference to FIG. 10 or FIG. 4, differential mode components of the EMI filter 1005 or 512, LDMand Cx, may be determined using the adjusted LC product. For example, in this case, the differential mode components may be selected first, based on the adjusted LC product, because the lowest frequency peaks may be primarily composed of differential mode noise. In some examples, an inductor (LDM) may be chosen first because inductors may require more volume than capacitors of the same magnitude. For example, the inductor (LDM) may be chosen to be 1.5 / / H. Once the inductor size is selected, equation 8 (below) may be used to determine the capacitor Cxsize. The common-mode choke (LCM) may be selected to be the same size as the differential mode inductor (LDM), 1.5 H. The size of the CYcapacitors may be reduced relative to the differential mode capacitor Cx(e.g., to 0.33 zF) because commonmode noise is primarily high frequency. The size of the CYcapacitors may also be reduced relative to the differential mode capacitor Cxto generally reduce the amount of leakage current to ground through the CYcapacitors.C_DM = LC / L_DM = (7.05 X 10A(-12) secA2) / (1.5 / / H) = 4.7 / zF (8)

[0124] The setpoint across all bins having the highest peak, the largest difference between a limit and a peak exceeding the limit (and, thus, the largest value of attenuation required), or the largest cutoff frequency may not correspond to the setpoint requiring the most substantial LC filter to attenuate the EMI to be below applicable limits. Rather, the largest LC product across all bins may corresponds to the setpoint requiring the most substantial LC filter. Thus, the largest LC product across all EMI bins may be used to identify a minimum size EMI filter that can attenuate EMI to be below the applicable limits. For example, although bin 6 indicates required attenuation of approximately 47 dB / zV at the setpoint of duty cycle 0.5 and output current 8A (see FIG. 15A),-36-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 because bin 6 is in the megahertz range, a smaller EMI filter may attenuate this EMI than the approximately 16 dB / iV required attenuation at the peak EMI setpoint in bin 1. For example, the EMI filter can be assumed to have a constant rolloff so that, when designed for bin 1, it also attenuates the other bins.

[0125] In some examples of blocks 1110 and / or 1115, the heatmaps discussed above are not generated. For example, the underlying data may be generated and stored (e.g., as an array or other data structure) in a memory, but may not be generated or displayed graphically (e.g., as shown in FIGs. 14-16B). Additionally, in some examples, a subset of the underlying data illustrated and described with respect to FIGS. 14-16B may be generated and stored. For example, for setpoints that do not have peak EMI above a limit (e.g., rectangles shown without a number in the heat maps), a cutoff frequency and / or LC product for these values may not be calculated. Further still, in some examples, a cutoff frequency and / or LC product is only generated for the setpoint of each bin (or a subset of the bins) having the highest peak EMI for that bin.

[0126] Accordingly, in some examples, in block 1110, determining the setpoint that results in the peak EMI may include determining a largest LC product for the range of setpoints, where the largest LC product corresponds to the setpoint of the range of setpoints that results in peak EMI. In some examples, determining the largest LC product may include calculating an attenuation value for each setpoint of the range of setpoints (as described above and illustrated, in part, in the heatmaps of FIGS. 14, 15A, and 15B). Determining the larges LC product may further include calculating, for each setpoint of at least a subset of the range setpoints, a cutoff frequency based on the attenuation value. For example, a cutoff frequency may be calculated for the setpoint with the peak EMI for each bin. Then, for each setpoint of the at least a subset of the range of setpoints, an LC product based on the cutoff frequency may be calculated. From this set of LC products, each corresponding to a particular setpoint, a largest of the LC products may be identified at the largest LC product for the range of setpoints. Then, in block 1115, the filter component values for the EMI filter may be generated based on this largest LC product, as described above.

[0127] Returning to FIG. 11, in block 1120, the process includes providing a variablefrequency converter circuit having an EMI filter with the EMI filter components generated in block 1115. For example, the variable-frequency converter circuit 1000 of FIG. 10 may be generated including the generated EMI filter components incorporated into the EMI filter 1005. In some examples, providing the variable-frequency converter circuit may include generating, storing, or-37-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 transmitting a digital representation of the variable-frequency converter circuit. Tn other examples, providing the variable-frequency converter circuit may include constructing the physical variablefrequency converter circuit (e.g., on a printed circuit board).

[0128] In some examples, after providing the variable-frequency converter circuit in block1020, validation may be performed. For example, block 1105 and 1110 may be repeated, this time with the EMI filter 1005 having the filter components generated in block 1115 included in the converter circuit 1000. Then, the peak EMI for each setpoint in each bin can be compared to applicable limits to determine whether the EMI of the converter circuit 1000 exceeds any of the limits. Returning to FIG. 13, plot 1305 shows the impact of the EMI filter 1005 designed using the above-described technique. In plot 1305, for the setpoint having duty cycle 0.6 and output current 56 A (the setpoint in bin 1 with peak EMI), each frequency bin limit is again labeled and shown as a horizontal black line. As shown in plot 1305, the EMI filter 1005 with filter components generated in block 1115 attenuates the EMI peaks that were previously exceeding the limits. FIGS. 17A and 17B illustrate plots 1700 and 1705 with frequency data resulting from current sweeps at duty cycle 0.4 (plot 1700) and 0.9 (plot 1705). As shown in the plots 1700 and 1705, the EMI peaks remain below the applicable limits (e.g., the CISPR25 Class 5 limits) illustrated as horizontal lines for each bin.

[0129] Again, although the process 1100 is primarily described with respect to the converter circuit 1000 of FIG. 10, the process 1100 may also be executed with respect to the converter systems 100, 200, 400, 500, and 600, as well as other variable-frequency converter circuits. Additionally, the process 1100 may be executed to design a switch-side EMI filter such as, for example, the switch-side EMI filter 118 or 618. In such examples, the EMI measurements for capturing EMI data may occur on the switch side of the converter (e.g., using a similar circuit as shown in FIG. 10, except at the connection nodes 226, 626). Thus, in some examples, the process 1100 may be used to design and generate one or more of the DC-side EMI filters 112 and / or the switch-side EMI filters 118 described herein.

[0130] In some examples, the process 1100 further includes (e.g., after validation) controlling the variable-frequency converter circuit generated in block 1120 to convert power. For example, controlling the power converter to convert power may include executing the process 800 of FIG. 8 described above.-38-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0131] Although the process 1100 for EMI filter design is primarily described with respect to a power converter to be controlled to soft-switch, in some examples, the process 1100 may be used to design an EMI filter for a power converter that will not be soft-switched.

[0132] Additional EMI Mitigation Techniques

[0133] Returning to FIG. 1, in some examples, the power converter system 100 of FIG. 1 may employ one or more additional EMI mitigation techniques to reduce EMI of the power converter system 100. As noted above, the reduction in EMI may also reduce leakage current of the power converter 115 of the power converter system 100. These additional EMI mitigation techniques may be used in addition to or instead of the DC-side EMI filter 112, the switch-side EMI filter 118, or both. In some examples, one or more of the additional EMI techniques may be used with the DC-side EMI filter 112, the switch-side EMI filter 118, or both. In some examples, when used with one or both of the EMI filters 112, 118, the additional EMI techniques may enable a reduced size of one or both of the EMI filters 112, 118, thereby increasing the power density and / or lowering the cost of the power converter system 100. As the converter systems 200, 400, 500, and 600 are examples of the power converter system 100, the additional EMI mitigation techniques may be implemented by any of these power converter systems as well.

[0134] The additional EMI mitigation techniques may be control techniques implemented by the control system 105 (e.g., software-controlled EMI mitigation). The additional EMI mitigation techniques may include an introduction of jitter into PWM control signaling used to drive the power switching elements 175 signals, an addition of an offset to a switching frequency of the PWM control signaling used to drive the power switching elements 175, or a combination thereof. Each of these techniques is described further below.

[0135] PWM Control Signaling with Jitter

[0136] In some examples, by introducing jitter into PWM control signaling, the control system 105 can reduce EMI and / or flatten EMI peaks, and / or can reduce leakage current and / or flatten leakage current peaks, produced by the power converter 115. For example, as discussed above with reference to FIG. 9, the control system 900 may generate a PWM signal for each halfbridge circuit of a corresponding variable-frequency, soft-switching power converter. In the case of a DC-DC converter or single-phase DC-AC converter having one half-bridge circuit (see, e.g.,-39-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303FIG. 2, 3, 4, or 5), the control system 900 may determine one switching frequency and one duty cycle for the PWM control signal (e.g., PWMa) to be applied to the upper switch and to the lower switch of the half-bridge circuit, where the PWM control signal applied to the upper switch may be the inverse of the PWM control signal applied to the lower switch. In the case of a three-phase DC-AC converter, the control system 900 may determine a switching frequency and a duty cycle for each phase of three phases (e.g., PWMa, PWMb, PWMc). These three PWM control signals would then be applied to the three half-bridge circuits of the three phases, respectively, where each PWM control signal applied to the upper switch may be the inverse of the PWM control signal applied to the lower switch of the particular half-bridge circuit.

[0137] By introducing jitter into these PWM control signals, EMI (and leakage current) may be reduced. For example, as demonstrated above, EMI may be higher at particular PWM control signal or converter setpoints than others. In some cases, for example, these EMI peaks may result from resonances in the converter circuit. Similarly, leakage current may be higher at particular PWM control signal or converter setpoints than others. By introducing jitter, these resonances may be interrupted, reducing the corresponding EMI peaks and / or leakage currents. The reduction can be to the magnitude of the EMI and / or leakage current peak. For example, the jitter can "spread out" the energy (or leakage current) measurement or magnitude at a given frequency. That is, spreading out the energy (or leakage current) may not dissipate the energy (or leakage current) entirely. However, the reduced peaks may prevent the system from violating a limit or otherwise reaching an undesirable level at a particular frequency or region, and / or may spread the energy or leakage current to a frequency where the energy or leakage current is acceptable.

[0138] FIG. 18A illustrates an example of a PWM control signal 1800 that may be generated by a control system (e.g., the control system 105 or 900) and applied to a switch of a variable-frequency, soft-switching power converter system, such as, for example, the upper switch 210 (or any other switch of the power switching elements 175 of one of the converters described herein).

[0139] FIG. 18B illustrates a modified PWM control signal 1805, which is an example of the PWM control signal 1800 including jitter 1806, also referred to as a PWM control signal modification 1806. For example, the control system generating the PWM control signal 1800 (e.g., the control system 105 or 900) may introducejitterto form the modified PWM control signal 1805,-40-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 which is then applied to the one or more switches of the variable-frequency, soft-switching power converter system. Here, the jitter takes the form of a temporary frequency modification. More particularly, the modified PWM control signal 1805 doubles in frequency temporarily, during the jitter portion. In other examples, the amount of frequency variation may be more or less than illustrated.

[0140] FIG. 18C illustrates a modified PWM control signal 1810, which is an example of the PWM control signal 1800 including jitter 1811, also referred to as a PWM control signal modification 1811. For example, the control system generating the PWM control signal 1800 (e.g., the control system 105 or 900) may introducejitterto form the modified PWM control signal 1810, which is then applied to the one or more switches of the variable-frequency, soft-switching power converter system. Here, the jitter takes the form of a temporary duty cycle modification. More particularly, the modified PWM control signal 1805 transitions from 50% duty cycle to 66% duty cycle temporarily, during the jitter portion. In other examples, the amount of duty cycle variation may be more or less than illustrated.

[0141] FIG. 18D illustrates a modified PWM control signal 1815, which is an example of the PWM control signal 1800 including jitter 1816, also referred to as a PWM control signal modification 1816. For example, the control system generating the PWM control signal 1800 (e.g., the control system 105 or 900) may introducejitterto form the modified PWM control signal 1815, which is then applied to the one or more switches of the variable-frequency, soft-switching power converter system. Here, the jitter takes the form of a temporary duty cycle modification and a temporary frequency modification. More particularly, the modified PWM control signal 1805 doubles in frequency and transitions from 50% duty cycle to 66% duty cycle temporarily, during the jitter portion. In other examples, the amount of variation may be more or less than illustrated.

[0142] FIGS. 18A-18D are provided merely to illustrate examples of types of jitter. The particular amount of time that the jitter is present and the amount of variation in the modified PWM control signal relative to the original PWM control signal (whether duty cycle and / or frequency) may vary. Further, the jitter may include more variation per instance of jitter than illustrated. For example, with reference to FIG. 18B, in some examples, the modified PWM control signal 1805 includes additional frequency modifications during the jitter portion. Thus, for example, the modified PWM control signal 1805 could have a first switching frequency (pre-jitter) and, then during the jitter portion, may include a second switching frequency for one or more pulses, a third-41-QB\ 175073.00303\98524560.2Attomey Docket No.: 175073.00303 switching frequency for one or more further pulses, a fourth switching frequency for one or more further pulses, and so on. Similarly, with reference to FIG. 18C, in some examples, the modified PWM control signal 1810 includes additional duty cycle modifications during the jitter portion, rather than varying from 50% duty cycle to 66% duty cycle during the jitter portion, and then returning back to 50% duty cycle. For example, the modified PWM control signal 1810 may include a first duty cycle (pre-jitter) (e.g., 50%) and then, during the jitter portion, may include a second duty cycle for one or more pulses, a third duty cycle for one or more further pulses, a fourth duty cycle for one or more pulses, and so on. Similarly, the modified PWM control signal 1815 may include additional frequency and / or duty cycle modifications during the jitter portion.

[0143] In some examples, the jitter introduced is randomized. For example, the length of time of the jitter portion, the length of time between jitter portions being inserted, the amount of variation of duty cycle during a jitter portion, and / or the amount of variation of frequency during a jitter portion may be randomized. For example, a random number generator (software or hardware element) may provide the control system 105 or 900 a random number (e.g., constrained within certain permissible limits) that may be used by the control system 105 or 900 to generate or introduce the jitter into the PWM control signal. That is, the random number(s) may indicate one or more of the length of time of the jitter portion, the length of time between jitter portions being inserted, the amount of variation of duty cycle during a jitter portion, and / or the amount of variation of frequency during a jitter portion.

[0144] In some examples, using one of the above techniques, the control system may determine whether to insert jitter, and the type of jitter to insert, on each processing cycle (where the processing cycle frequency of the control system may be less than the switching frequency). The control system may then selectively insert (or not insert) jitter into the PWM control signal each processing cycle.

[0145] PWM Control Signaling with Switching Frequency Offset

[0146] In some examples, by introducing a switching frequency offset into PWM control signaling, the control system 105 can reduce EMI and / or flatten EMI peaks produced by the power converter 115. For example, as discussed above with reference to FIG. 9, the control system 900 may generate a PWM signal for each half-bridge circuit of a corresponding variable-frequency, soft-switching power converter. In the case of a DC-DC converter or single-phase DC-AC-42-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 converter having one half-bridge circuit (see, e.g., FIG. 2, 3, 4, or 5), the control system 900 may determine one switching frequency and one duty cycle for the PWM control signal (e.g., PWMa) to be applied to the upper switch and to the lower switch of the half-bridge circuit, where the PWM control signal applied to the upper switch may be the inverse of the PWM control signal applied to the lower switch. In the case of a three-phase DC-AC converter, the control system 900 may determine a switching frequency and a duty cycle for each phase of three phases (e.g., PWMa, PWMb, PWMc). These three PWM control signals would then be applied to the three half-bridge circuits of the three phases, respectively, where each PWM control signal applied to the upper switch may be the inverse of the PWM control signal applied to the lower switch of the particular half-bridge circuit.

[0147] By introducing a switching frequency offset into these PWM control signals, EMI may be reduced. For example, as demonstrated above, EMI may be higher at particular PWM control signal or converter setpoints than others. In some cases, for example, these EMI peaks may result from resonances in the converter circuit. By introducing a switching frequency offset, these resonances may be interrupted, reducing the corresponding EMI peaks.

[0148] As noted above, FIG. 18A illustrates an example of a PWM control signal 1800 that may be generated by a control system (e.g., the control system 105 or 900) and applied to a switch of a variable-frequency, soft-switching power converter system, such as, for example, the upper switch 210 (or any other switch of the power switching elements 175 of one of the converters described herein). In some examples, the control system generating the PWM control signal 1800 (e.g., the control system 105 or 900) may introduce a switching frequency offset to form the modified PWM control signal, which is then applied to the one or more switches of the variablefrequency, soft-switching power converter system. For example, the control system may determine a switching frequency offset. To determine the switching frequency offset, the control system may obtain a predetermined value (e.g., from a memory) or from a random number generator (e.g., software or hardware element) that provides a random number (constrained within certain permissible limits) that is indicative of the switching frequency offset and may be used by the control system 105 or 900 to generate the switching frequency offset. In some examples, the control system 105 or 900 may generate an offset waveform (e.g., sinusoidal or triangular) where the value of the waveform at a particular moment may be indicative of the switching frequency-43-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 offset. The switching frequency offset may also be referred to as a PWM control signal modification, and resulting control signal may be referred to as a modified PWM control signal.

[0149] FIG. 19 illustrates an example of a modified PWM control signal 1900 resulting from a first PWM control signal modification 1905 (a first switching frequency offset) and from a second PWM control signal modification 1910 (a second switching frequency offset). More particularly, the modified PWM control signal 1900 begins with a switching frequency of Fsw. At the first PWM control signal modification 1905, the modified PWM control signal 1900 has a switching frequency of Fswi, which is the result of a switching frequency offset of a, where a has a positive value (e.g., Fswi = Fsw + a). At the second PWM control signal modification 1910, the modified PWM control signal 1900 has a switching frequency of Fsw2, which is the result of a switching frequency offset of b, where b has a negative value (e.g., Fsw2 = Fsw + Z>). The number of pulses at which the switching frequency has the offset a or b varies in other examples. Additionally, the value of the offset a and b varies in some examples (e.g., the offset a may be negative, the offset b may be positive, both offsets a and b may be positive, or both offsets a and b may be negative).

[0150] In some examples, using one of the above techniques, the control system may determine the switching frequency offset on each processing cycle (where the processing cycle frequency of the control system may be less than the switching frequency). The control system may then adjust the switching frequency of the PWM control signal each processing cycle using the determined switching frequency offset. Thus, with reference to FIG. 9, the PWM control signal output by the local sub-controller 160a (PWMa) may have a switching frequency equal to Fsw (e.g., calculated as described above with respect to FIG. 9) plus the switching frequency offset. For example, in a first cycle, the switching frequency offset may be 25 kHz, and in the next cycle, the switching frequency offset may be -2 kHz, and in a third cycle, the switching frequency offset may be another value. The particular amount of the offset may vary, and may be constrained within limits (e.g., in terms of a percentage of the switching frequency or by absolute or predetermined values).

[0151] In some examples, PWM control signal modification, whether jitter or a switching frequency offset, may be implemented by the control system 105 as a default (e.g., each cycle). In other examples, the control system 105 or 900 may implement the PWM control signal modification, whether jitter or a switching frequency offset, selectively. To selectively implement-44-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 the PWM control signal modification, the control system 105 or 900 may implement a process 2000 (discussed below with respect to FIG. 20), or may apply a predetermined schedule. For example, a predetermined schedule may indicate to the control system 105 or 900 to apply the PWM control signal modification at predetermined times or intervals, such as, for example, every x milliseconds, every ; PWM pulses, or the like (e.g., where x and are positive, real numbers). In such examples, the control system 105 or 900 may determine a PWM operational parameters for a PWM control signal (see, e.g., block 2005 discussed below), generate a PWM control signal modification for the PWM control signal when the predetermined schedule indicates to do so (e.g., when x milliseconds have lapsed or y PWM pulses have occurred), and then control the power switching elements with the modified PWM control signal (see, e.g., block 2015 discussed below). The PWM control signal modification may include an introduction of jitter or a switching frequency offset to the PWM control signal to provide a modified PWM control signal, as described above.

[0152] FIG. 20 illustrates a process 2000 for operating a power converter. More particularly, the process 2000 enables control of a power converter using selective application of a PWM control signal modification. This PWM control signal modification can mitigate or reduce EMI or leakage current. The process 2000 is described as being carried out by a control system and, in particular, by the control system 105 (FIG. 1) or 900 (FIG. 9) controlling the power converter system 100 implemented as, for example, one of the converter systems 200, 400, 500, or 600. As discussed above, the control system 900 is an example of the control system 105 and may be used to control a three-phase converter (as shown), but may also be used to control a singlephase power converter where, for example, the local sub-controllers 160b, 160c may not be included or are idle. However, in some embodiments, the process 2000 is implemented by another control system and / or with respect to another power converter system (e.g., a split-phase converter or a converter with more than three phases). Additionally, although the blocks of the process 2000 are illustrated in a particular order, in some embodiments, one or more of the blocks may be executed partially or entirely in parallel, may be executed in a different order than illustrated in FIG. 20, or may be bypassed.

[0153] In block 2005, a control system (e.g., the control system 105 or 900) determines PWM operational parameters for a PWM control signal for controlling a variable-frequency power-45-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 converter. The variable-frequency power converter be, for example, the power converter 1 15, 215, and / or 615. Accordingly, the variable-frequency power converter may include a DC voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, an LC fdter comprising a filter inductor and a filter capacitor, and a half-bridge circuit including power switching elements including an upper power switching element and a lower power switching element. See, for example, such components described with respect to the power converters 215 and 615 in FIGS. 2 and 6.

[0154] The PWM operational parameters for the PWM control signal may include a duty cycle (D) and / or a switching frequency (Fsw). In some examples, the control system determines the duty cycle and / or switching frequency using a technique as described above with respect to block 810 of FIG. 8.

[0155] In block 2010, the control system generates a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variablefrequency power converter are within a defined range. For example, the PWM control signal modification may include an introduction of jitter or a switching frequency offset to the PWM control signal to provide a modified PWM control signal, as described above. For example, in FIG. 18A, an example of a PWM control signal 1800 is illustrated, and in FIGS. 18B, 18C, and 18D, examples of modified PWM control signals 1805, 1810, and 1815 are illustrated with PWM control signal modifications 1806, 1811, and 1816 (examples of jitter). Additionally, FIG. 19 illustrates another modified PWM control signal 1900 with PWM control signal modifications 1905 and 1910 (examples of switching frequency offsets).

[0156] In some examples, in block 2010, the control system determines the one or more converter system characteristics of the variable-frequency power converter. For example, the one or more converter system characteristics for the variable-frequency power converter include one or more of the switching frequency (e.g., determined in block 2005), the duty cycle (e.g., determined in block 2005), a change in switching frequency (e.g., above a threshold or above a threshold within a defined time period), an output current setpoint of the variable-frequency power converter, an output voltage setpoint of the variable-frequency power converter, an output current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an input current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an output current ramp-up (e.g., either sensed or commanded-46-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 via setpoints), an output voltage ramp-up (e.g., either sensed or commanded via setpoints), an operational mode (e.g., single-phase mode, split-phase mode, three-phase mode), an inductor value of the fdter inductor of the LC filter (e.g., in pH), or a capacitor value of the filter capacitor of the LC filter (e.g., in pF). Accordingly, one or more of the converter system characteristics may be determined operational parameters for controlling the converter (e.g., switching frequency, duty cycle, change in switching frequency, output current setpoint or ramp-up, output voltage setpoint or ramp-up, or operational mode), physical characteristics of the converter (e.g., the inductor value or a capacitance value), or a sensed characteristic of the converter (e.g., the output current, output voltage, input current, input voltage, output current ramp-up, output voltage ramp-up). The physical characteristics of the converter may be stored in a memory of the control system (e.g., the memory 157) and control system may determine these physical characteristics by reading the physical characteristics from the memory. The control system may determine the sensed characteristics of the converter from sensor data output by sensors for the converter (see, e.g., sensors 140 of FIG. 1). The control system may determine the operational parameters for controlling the converter from input data received via the I / O interface 142 or from reading the operational param eter(s) from a memory (e.g., the memory 157).

[0157] Additionally, in some examples, in block 2010, the control system determines, in response to the one or more converter system characteristics being within the defined range, to generate the PWM control signal modification to the PWM control signal. For example, the control system may have one or more defined ranges for the one or more converter system characteristics, where each defined range or set of defined ranges corresponds to an increased EMI or leakage current of the power converter or EMI or leakage current above a certain level. The control system may compare the one or more converter system characteristics to the define range(s) and, when within the defined range(s), may determine to generate the PWM control signal modification. As an example, the defined range may include a frequency range for the switching frequency of the converter that is expected to result in an increase in EMI or leakage current from the variablefrequency power converter (e.g., above a certain level). When the control system determines that the switching frequency (e.g., determined in block 2005) is within the defined range, the control system may determine to generate a PWM control signal modification to reduce or mitigate EMI or leakage current that would otherwise result if the control system were to control the power switching elements with the initially determined switching frequency. The particular defined-47-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 ranges may be determined through testing (see, e.g., discussion with respect to FIGS. 10-17B). Additionally, in some examples, the control system uses a set of defined ranges for multiple converter system characteristics and, if any one of, a predetermined set of, or all of the converter system characteristics is within an associated defined range, the control system determines to generate a PWM control signal modification to reduce or mitigate EMI or leakage current. As one example, the control system may have a defined frequency range and a defined duty cycle range and, when the determined switching frequency and duty cycle both fall within the respective associated defined range, the control system determines to generate a PWM control signal modification to reduce or mitigate EMI or leakage current. Thus, the PWM control signal modifications may be implemented selectively when an increase in EMI or leakage current is expected, and can be avoided or not implemented when an increase in EMI is not expected.

[0158] In block 2015, the control system controls the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal. For example, the control system may drive the power switching elements of the half-bridge circuit of the converter (e.g., the half-bridge circuit 205 or a half-bridge circuit of the three half-bridge circuit 605) with the modified PWM control signal control. For example, the control system 105 may generate and provide the modified PWM control signal control for each switch of the power switching elements 175 of the half-bridge circuit. The modified PWM control signal for the upper switch 210 and for the lower switch 211 may be an inverse of one another (e.g., when the PWM control signal for the upper switch 210 is high or “ON”, the PWM control signal for the lower switch 211 is low or “OFF”). With reference to FIG. 6, the upper and lower switches 210, 211 for each respective half-bridge circuit of the three half-bridge circuits 606 may have a distinct modified PWM control signal (e.g., as determined in block 2010). In such cases, the control system 105 may generate and provide a first modified PWM control signal for the upper and lower switches 210, 211 of phase A having a first PWM control signal modification determined in block 2010, a second modified PWM control signal for the upper and lower switches 210, 211 of phase B having a second PWM control signal modification determined in block 2010, and a third modified PWM control signal for the upper and lower switches 210, 211 of phase C having a third PWM control signal modification determined in block 2010. As with the single half-bridge circuit example, the modified PWM control signal to the upper-48-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 and lower switches 210, 211 of each respective half-bridge circuit may be the inverse of one another.

[0159] As noted, the process 2000 may be implemented with one or more of the converter systems 200, 400, 500, and 600 described herein and, accordingly, with converters that include one or more physical EMI fdters. In some cases, mitigating EMI spikes at lower switching frequencies with physical hardware (e.g. an EMI filter) can require larger filter components (e.g., capacitors and / or inductors) than mitigating EMI spikes at higher switching frequencies. Accordingly, in some examples, the EMI mitigation control techniques of the process 2000 can be implemented to mitigate EMI spikes at lower frequencies, and then one or more EMI filters can be used to mitigate remaining EMI spikes that may occur at higher frequencies. For example, the defined range(s) used to determine whether the control system implements a PWM control signal modification (see block 2010) can specify lower frequency range(s). With this approach, the EMI filter size can be reduced and, thus, the overall size of a power converter system can be reduced, increasing power density of the power converter system.

[0160] For example, with reference to plot 1300 of FIG. 13, the process 2000 may be used to reduce EMI spikes in bins 1 and 2, and then the EMI design process 1100 may be used to design the EMI filters to reduce the EMI spikes in bins 3-7. For the process 2000 to reduce the EMI spikes in bins 1 and 2, the control system may store and use defined ranges in block 2010 that include the setpoints associated with each spike above an EMI limit in bins 1 and 2. For example, each spike in EMI above a limit in bin 1 and in bin 2 may be associated with a defined range that includes a duty cycle and an output current, a switching frequency, and / or another set of characteristics. Then, as described with respect to the process 2000, during operation, the control system may selectively modify a PWM control signal with jitter or a switching frequency offset to mitigate the EMI. In some examples, using the process 2000 as described to selectively modify the PWM control signals may reduce the EMI in bins 1 and 2 below applicable limits, and then the EMI design process 1100 may be used to design the EMI filters to reduce the EMI spikes in bins 3-7. In some examples, using the process 2000 as described to selectively modify the PWM control signals may reduce the EMI in bins 1 and 2, but not entirely below the applicable limits. In such cases, the EMI design process 1100 may be used to design the EMI filters to reduce the EMI spikes in bins 1-7, as previously described with respect to FIG. 11. However, the resulting EMI filter may still be-49-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 reduced in size (relative to not using the process 2000) because the amount of attenuation required to reduce EMI spikes below applicable limits in bins 1 and 2 is reduced.

[0161] In some examples, the control system 105 or 905 may implement the process 2000 on each processing cycle (where the processing cycle frequency of the control system may be less than the switching frequency). The control system 105 or 905 may, thus, modify the PWM control signal each processing cycle using these techniques.

[0162] FIG. 21 illustrates examples of leakage current versus switching frequency data plots for a power converter (e.g., the power converter 115), according to some embodiments. More particularly, FIG. 21 illustrates a first plot 2100 of leakage current (y-axis) versus switching frequency (x-axis) for a power converter in which jitter is not inserted or used to modify a PWM control signal that drives switches of the power converter. In the first plot 2100, a leakage current limit 2105 (e.g., which may be specified by a standards setting body) is provided. Additionally, the leakage current of the power converter is shown as root mean squared (RMS) leakage current 2110 and as spatial leakage current 2115. In some examples, the RMS leakage current 2110 may be relevant to consider against the leakage current limit 2105 when frequencies are below a threshold frequency (illustrated by dashed line 2120), and the spatial leakage current 2115 may be relevant to consider against the leakage current limit 2105 when frequencies are above the threshold frequency (illustrated by the dashed line 2120). As shown in the first plot 2100, at certain frequencies above, the spatial leakage current 2115 exceeds the leakage current limit 2105 in area 2125.

[0163] FIG. 21 further illustrates a second plot 2150 of leakage current (y-axis) versus switching frequency (x-axis), in which jitter is inserted or used to modify a PWM control signal that drives switches of the same power converter as used to generate the first plot 2100. In the second plot 2150, the leakage current of the power converter is shown as root mean squared (RMS) leakage current 2160 and as spatial leakage current 2165. In some examples, the RMS leakage current 2160 may be relevant to consider against the leakage current limit 2105 when frequencies are below a threshold frequency (illustrated again by the dashed line 2120), and the spatial leakage current 2165 may be relevant to consider against the leakage current limit 2105 when frequencies are above the threshold frequency (illustrated by the dashed line 2120). As shown in the second plot 2150, the leakage current, including both the RMS leakage current 2160 and the spatial leakage current 2165, does not exceed the leakage current limit 2105. Rather, the jitter used to-50-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 modify the PWM control signal(s) that drive the switches of the power converter reduce peak(s) of the leakage current and the resulting leakage current, and neither the RMS leakage current 2160 or the spatial leakage current 2165 exceed the leakage current limit. The first and second plots 2100 and 2150 are merely example plots showing an example result of modifying a PWM control signal with jitter to reduce leakage current. In other examples, additional peaks may be flattened or reduced, the amount of flattening or reduction of peaks may vary, or the leakage current waveforms may otherwise vary.

[0164] FIG. 22 illustrates a computer system 2200. The computer system 2200 includes a processor 2202, a memory 2204, and an input / output (I / O) interface 2206. The computer system 2200 is an example of a computer system that may implement the process 1100 of FIG. 11. The computer system 2200 may be configured with various modules (e.g., various software modules) to implement various functions. In some implementations, the memory 2204 may store one or more software modules in the form of instructions that, when executed by the processor 2202, cause the computer system 2200 to perform any one or more of the operations described herein, including the blocks of the process 1100. Additionally or alternatively, in some examples, the processor 2202 may be configured to load and / or execute instructions from another non-transitory computer-readable medium (e.g., cloud storage or from the memory of another device) to implement the process 1100.

[0165] The I / O interface 2206 may include interface components to permit the communication of data to and from external devices or sources. For example, the I / O interface 2206 may include communication ports and / or interfaces to permit communication with other computer devices. The communication ports and / or interfaces may permit input and output via wired protocols (e.g., Ethernet, Universal Serial Bus (USB), FireWire, etc.) and / or wireless protocols (e.g., Wi-Fi, Bluetooth, Near Field Communication (NFC), 5G, 4G, etc.). The VO interface 2206 may additionally or alternatively include communication ports and / or interfaces to permit communication with a user. For example, the I / O interface 2206 may include interfaces for a mouse, a keyboard, a display, a graphical user interface (GUI), buttons, switches, etc.

[0166] Performing the various techniques and operations described herein may be facilitated by an electronic controller (e.g., a processor-based computing device), such as, for example, a central controller 150, local controller 160, control system 105, control system 900, or the like as described herein. Such an electronic controller may include a processor-based device-51-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303 such as a computing device, and so forth, that may include a central processor unit (CPU) or a processing core. In addition to the CPU or processing core, the system includes main memory, cache memory, and bus interface circuits. The electronic controller may include a memory storage device, such as a hard drive (solid state hard drive, or other types of hard drive), or flash drive associated with the computer system. The electronic controller may further include a keyboard, or keypad, or some other user input interface, and a monitor, e.g., an LCD (liquid crystal display) monitor, that may be placed where a user can access them.

[0167] The electronic controller is configured to facilitate, for example, the implementation of a power converter (e g., by controlling the switching devices of, for example, a non-isolated power converter system). The storage device may thus include a computer program product that when executed on the electronic controller (which, as noted, may be a processor-based device) causes the processor-based device to perform operations to facilitate the implementation of procedures and operations described herein. The electronic controller may further include peripheral devices to enable input / output functionality. Such peripheral devices may include, for example, flash drive (e.g., a removable flash drive), or a network connection (e.g., implemented using a USB port and / or a wireless transceiver), for downloading related content to the connected system. Such peripheral devices may also be used for downloading software containing computer instructions to enable general operation of the respective system / device. Alternatively and / or additionally, in some embodiments, special purpose logic circuitry, e.g., an FPGA (field programmable gate array), an ASIC (application-specific integrated circuit), a DSP processor, a graphics processing unit (GPU), application processing unit (APU), etc., may be used in the implementations of the electronic controller. Other modules that may be included with the electronic controller may include a user interface to provide or receive input and output data. The electronic controller may include an operating system.

[0168] Computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and may be implemented in a high-level procedural and / or object-oriented programming language, and / or in assembly / machine language. As used herein, the term “machine-readable medium” refers to any non-transitory computer program product, apparatus and / or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and / or data to a-52-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 programmable processor, including a non-transitory machine-readable medium that receives machine instructions as a machine-readable signal.

[0169] In some embodiments, any suitable computer readable media can be used for storing instructions for performing the processes / operations / procedures described herein. For example, in some embodiments computer readable media can be transitory or non-transitory. For example, non-transitory computer readable media can include media such as magnetic media (such as hard disks, floppy disks, etc.), optical media (such as compact discs, digital video discs, Blu- ray discs, etc ), semiconductor media (such as flash memory, electrically programmable read only memory (EPROM), electrically erasable programmable read only Memory (EEPROM), etc ), any suitable media that is not fleeting or not devoid of any semblance of permanence during transmission, and / or any suitable tangible media. As another example, transitory computer readable media can include signals on networks, in wires, conductors, optical fibers, circuits, any suitable media that is fleeting and devoid of any semblance of permanence during transmission, and / or any suitable intangible media.

[0170] The presently disclosed subject matter is further described in the following materials appended hereto:Appendix A: Conducted Emissions Prediction and EMI Filter Design for a Variable- Frequency, Soft-Switching Inverter (Fix et al.)Appendix B: Maximum-Emission Operating Setpoint for the Electromagnetic Compliance of a Variable-Frequency, Soft- Switching Converter (Fix et al.)

[0171] Although particular embodiments have been disclosed herein in detail, this has been done by way of example for purposes of illustration only, and is not intended to be limiting with respect to the scope of the appended claims, which follow. Features of the disclosed embodiments can be combined, rearranged, etc., within the scope of the invention to produce more embodiments. Some other aspects, advantages, and modifications are considered to be within the scope of the claims provided below. The claims presented are representative of at least some of the embodiments and features disclosed herein. Other unclaimed embodiments and features are also contemplated.EXAMPLES

[0172] Example 1 : A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for a power converter system comprising: a variable--53-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 frequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the variable-frequency power converter including: a DC link capacitor connected across the DC bus, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node; and a control system coupled to the variable-frequency power converter, the control system is configured to: control the variable-frequency power converter to convert power.

[0173] Example 2: The method, apparatus, and / or non-transitory computer readable medium of Example 1, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein: the EMI inductor is a first EMI inductor and the EMI filter further includes a second EMI inductor, the first EMI inductor is connected between the positive DC node and a positive DC EMI node, the second EMI inductor is connected between the negative DC node and a negative DC EMI node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

[0174] Example 3: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 2, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein: the EMI inductor is a first differential mode (DM) inductor and the EMI filter further includes a second DM inductor and a common mode (CM) inductor, the first DM inductor and one leg of the CM inductor are connected between the positive DC node and a positive DC EMI node, the second DM inductor and a second leg of the CM inductor are connected between the negative DC node and a negative DC EMI node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

[0175] Example 4: The method, apparatus, and / or non-transitory computer readable medium of Example 3, further comprising an EMI capacitor coupled between a first node joining the first DM inductor and the CM inductor and a second node joining the second DM inductor and the CM inductor.-54-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0176] Example 5: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 4, wherein the EMI fdter is a DC-side EMI filter connected across the DC bus, and wherein: the EMI inductor is a first differential mode (DM) inductor and the EMI filter further includes a common mode (CM) inductor and an EMI capacitor, the first DM inductor and one leg of the CM inductor are connected between the positive DC node and a positive DC EMI node, a second leg of the CM inductor is connected between the negative DC node and a negative DC EMI node, the EMI capacitor coupled between a first node joining the first DM inductor and the CM inductor and the negative DC node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

[0177] Example 6: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 5, wherein the EMI filter is a switch-side EMI filter connected across the connection nodes, and wherein: the EMI inductor is a first EMI inductor and the EMI filter further includes a second EMI inductor, the first EMI inductor is connected between a first connection node of the connection nodes and a first switch-side EMI node, the second EMI inductor is connected between a second connection node of the connection nodes and a second switch-side EMI node, the first capacitor is connected between the first switch-side EMI node and the ground node, and the second capacitor is connected between the second switch-side EMI node and the ground node.

[0178] Example 7: The method, apparatus, and / or non-transitory computer readable medium of Example 6, wherein the first connection node is connected to a filter node that is connected to the filter inductor and to the filter capacitor, and wherein the second connection node is connected to the negative DC node.

[0179] Example 8 : The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 7, wherein the EMI filter is a switch-side EMI filter that is connected across the connection nodes, and the variable-frequency power converter further comprises a DC-side EMI filter that is connected across the DC bus, the DC-side EMI filter comprising: a first DC-side EMI inductor, a first DC-side capacitor, and a second DC-side capacitor, wherein the first and second DC-side capacitors are connected at a ground node.

[0180] Example 9: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 8, wherein the variable-frequency power converter is a three--55-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three-phase power converter, the three-phase power converter further comprising: a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.

[0181] Example 10: The method, apparatus, and / or non-transitory computer readable medium of Example 9, wherein the EMI filter is a DC-side EMI filter, and wherein the variablefrequency power converter further comprise: a three-phase switch-side AC filter connected between the first, second, and third AC connection nodes and EMI AC output nodes, the three- phase switch-side AC filter comprising: a first capacitive stage; a first inductive stage; a second capacitive stage; and a second inductive stage.

[0182] Example 11: The method, apparatus, and / or non-transitory computer readable medium of Example 10, wherein: the first capacitive stage includes a first A-phase capacitor connected to the first AC connection node, a first B-phase capacitor connected to the second AC connection node, and a first C-phase capacitor connected to the third AC connection node, wherein the first A-phase, B-phase, and C-phase capacitors are each also connected to a first common node; the first inductive stage includes a first A-phase inductor connected to the first AC connection node, a first B-phase inductor connected to the second AC connection node, and a first C-phase inductor connected to the third AC connection node; the second capacitive stage includes a second A-phase capacitor connected to the first A-phase inductor, a second B-phase capacitor connected to the first B-phase inductor, a second C-phase capacitor connected to the first C-phase inductor, and a common capacitor coupled between ground and a second common node connecting the second A-phase, B-phase, and C-phase capacitors together; and the second inductive stage includes a second A-phase inductor connected to the first A-phase inductor, a second B-phase inductor connected to the first B-phase inductor, and a second C-phase inductor connected to the first C-phase inductor.-56-QB\175073.00303\98524560.2Attomey Docket No.: 175073.00303

[0183] Example 12: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 11, wherein, to control the variable-frequency power converter to convert power, the control system is configured to: determine at least one electrical operational characteristic for the variable-frequency power converter; determine a duty cycle and a switching frequency based on the at least one electrical operational characteristic; and drive the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency.

[0184] Example 13: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 1 to 12, wherein the control system is further configured to: determine PWM operational parameters for a PWM control signal; generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0185] Example 14: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for a power converter system comprising: sweeping control signals that drive a variable-frequency converter circuit to drive the variablefrequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different combinations of duty cycles and switching frequencies; determining a setpoint of the range of setpoints that results in peak electromagnetic interference (EMI) by the variable-frequency converter circuit; generating filter component values for an EMI filter of the variable-frequency converter based on the setpoint determined to result in peak EMI; and providing a modified variable-frequency converter circuit having the EMI filter with the filter components values.

[0186] Example 15: The method, apparatus, and / or non-transitory computer readable medium of Example 14, further comprising: sweeping further control signals that drive the modified variable-frequency converter circuit over at least a subset of the range of setpoints; and validating that resulting EMI from the modified variable-frequency converter circuit from sweeping the further control signals is below one or more EMI limits.

[0187] Example 16: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 14 to 15, further comprising: capturing, while sweeping the control-57-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 signals, electrical characteristic data of the variable-frequency converter circuit that is indicative of EMI being produced by the variable-frequency converter circuit.

[0188] Example 17: The method, apparatus, and / or non-transitory computer readable medium of Example 16, wherein determining the setpoint of the range of setpoints that results in peak EMI comprises: identifying, for each setpoint of the range of setpoints, a peak EMI value; determining a largest value from the peak EMI values and a corresponding setpoint that corresponds to the largest value; and identifying the setpoint of the range of setpoints that results in peak EMI as the corresponding setpoint that corresponds to the largest value.

[0189] Example 18: The method, apparatus, and / or non-transitory computer readable medium of Example 16, wherein determining the setpoint of the range of setpoints that results in peak EMI comprises: determining a largest LC product for the range of setpoints, wherein the largest LC product corresponds to the setpoint of the range of setpoints that results in peak EMI and corresponds to a size of the EMI filter to attenuate the peak EMI being produced by the variable-frequency converter circuit at the setpoint.

[0190] Example 19: The method, apparatus, and / or non-transitory computer readable medium of Example 18, wherein determining the largest LC product for the range of setpoints comprises: calculating an attenuation value for each setpoint of the range of setpoints; calculating, for each setpoint of at least a subset of the range setpoints, a cutoff frequency based on the attenuation value; calculating, for each setpoint of the at least a subset of the range of setpoints, an LC product based on the cutoff frequency; and identifying a largest of the LC products calculated as the largest LC product.

[0191] Example 20: The method, apparatus, and / or non-transitory computer readable medium of Example 19, wherein each setpoint of the at least a subset of the range of setpoints corresponds to a respective bin of a plurality of bins, and wherein each bin of the plurality of bins corresponds to a distinct frequency range and EMI limit.

[0192] Example 21: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 14 to 20, wherein the modified variable-frequency converter circuit includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node; a switch-side section including connection nodes; a DC link capacitor connected across the DC bus; and a half-bridge circuit including: power switching elements-58-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor.

[0193] Example 22: The method, apparatus, and / or non-transitory computer readable medium of Example 21, wherein the EMI filter is a DC-side EMI filter connected across the DC bus or a switch-side EMI filter connected to the connection nodes, wherein the EMI filter includes an EMI inductor, a first capacitor, and a second capacitor, and wherein the first and second capacitor are connected at a ground node.

[0194] Example 23: The method, apparatus, and / or non-transitory computer readable medium of Example 21, further comprising: determining at least one electrical operational characteristic for the modified variable-frequency converter circuit; determining a duty cycle and a switching frequency based on the at least one electrical operational characteristic; and driving the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency to control the modified variable-frequency converter circuit to convert power.

[0195] Example 24: The method, apparatus, and / or non-transitory computer readable medium of Example 21, further comprising: determining PWM operational parameters for a PWM control signal; generating a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the modified variable-frequency converter circuit are within a defined range; and controlling the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0196] Example 25: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for a power converter system comprising: a variable-frequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the power converter including: a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; and a control system coupled to the variable-frequency power converter, the control system is configured to: determine PWM operational parameters for a PWM control signal, generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable--59-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 frequency power converter are within a defined range, and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

[0197] Example 26: The method, apparatus, and / or non-transitory computer readable medium of Example 25, wherein the control system is further configured to: determine the one or more converter system characteristics of the variable-frequency power converter, and determine, in response to the one or more converter system characteristics being within the defined range, to generate the PWM control signal modification to the PWM control signal.

[0198] Example 27: The method, apparatus, and / or non-transitory computer readable medium of Example 26, wherein the one or more converter system characteristics is a switching frequency of the PWM operational parameters, and wherein the defined range is a frequency range for controlling switching of the power switching elements that corresponds to an increase in electromagnetic interference.

[0199] Example 28: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 25 to 27, wherein the PWM operational parameters for the PWM control signal are a duty cycle and a switching frequency.

[0200] Example 29: The method, apparatus, and / or non-transitory computer readable medium of Example 28, wherein, to determine the switching frequency, the control system is configured to select the switching frequency to ensure soft switching of the power switching elements.

[0201] Example 30: The method, apparatus, and / or non-transitory computer readable medium of Example 28, wherein the one or more converter system characteristics for the variablefrequency power converter include one or more of a switching frequency, a duty cycle, an output current of the variable-frequency power converter, an input current of the variable-frequency power converter, an inductor value of the filter inductor, or a capacitor value of the filter capacitor.

[0202] Example 31: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 25 to 30, wherein the PWM control signal modification is jitter applied to the PWM control signal.

[0203] Example 32: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 25 to 31, wherein the PWM control signal modification is a switching frequency offset applied to the PWM control signal.-60-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303

[0204] Example 33: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 25 to 30, further comprising: a DC link capacitor of the variablefrequency power converter that is coupled across the DC bus; and an electromagnetic interference (EMI) fdter connected across the DC bus or the connection nodes, the EMI fdter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.

[0205] Example 34: The method, apparatus, and / or non-transitory computer readable medium of any of Examples 25 to 30, wherein the variable-frequency power converter is a three- phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three-phase power converter, the three-phase power converter further comprising: a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.

[0206] Example 35: The method, apparatus, and / or non-transitory computer readable medium of Example 34, wherein the PWM control signal and the modified PWM control signal are for the first half-bridge circuit, and wherein the control system is further configured to: determine second PWM operational parameters for a second PWM control signal and third PWM operational parameters for a third PWM control signal, generate a second PWM control signal modification to the second PWM control signal when the one or more converter system characteristics of the variable-frequency power converter are within the defined range, control the second power switching elements with a second modified PWM control signal, wherein the second modified PWM control signal results from the second PWM control signal modification to the second PWM control signal, and control the third power switching elements with a third modified PWM control signal, wherein the third modified PWM control signal results from the third PWM control signal modification to the third PWM control signal.-61-QB\ 175073.00303198524560.2

Claims

Attomey Docket No.: 175073.00303WHAT TS CLAIMED IS:

1. A power converter system comprising: a variable-frequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the variable-frequency power converter including: a DC link capacitor connected across the DC bus, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC fdter comprising a fdter inductor and a filter capacitor; an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node; and a control system coupled to the variable-frequency power converter, the control system is configured to: control the variable-frequency power converter to convert power.

2. The power converter system of claim 1, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein: the EMI inductor is a first EMI inductor and the EMI filter further includes a second EMI inductor, the first EMI inductor is connected between the positive DC node and a positive DC EMI node, the second EMI inductor is connected between the negative DC node and a negative DC EMI node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

3. The power converter system of claim 1 , wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein:-62-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 the EMI inductor is a first differential mode (DM) inductor and the EMI filter further includes a second DM inductor and a common mode (CM) inductor, the first DM inductor and one leg of the CM inductor are connected between the positive DC node and a positive DC EMI node, the second DM inductor and a second leg of the CM inductor are connected between the negative DC node and a negative DC EMI node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

4. The power converter system of claim 3, further comprising an EMI capacitor coupled between a first node joining the first DM inductor and the CM inductor and a second node joining the second DM inductor and the CM inductor.

5. The power converter system of claim 1, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein: the EMI inductor is a first differential mode (DM) inductor and the EMI filter further includes a common mode (CM) inductor and an EMI capacitor, the first DM inductor and one leg of the CM inductor are connected between the positive DC node and a positive DC EMI node, a second leg of the CM inductor is connected between the negative DC node and a negative DC EMI node, the EMI capacitor coupled between a first node joining the first DM inductor and the CM inductor and the negative DC node, the first capacitor is connected between the positive DC EMI node and the ground node, and the second capacitor is connected between the negative DC EMI node and the ground node.

6. The power converter system of claim 1, wherein the EMI filter is a switch-side EMI filter connected across the connection nodes, and wherein: the EMI inductor is a first EMI inductor and the EMI filter further includes a second EMI inductor,-63-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 the first EMI inductor is connected between a first connection node of the connection nodes and a first switch-side EMI node, the second EMI inductor is connected between a second connection node of the connection nodes and a second switch-side EMI node, the first capacitor is connected between the first switch-side EMI node and the ground node, and the second capacitor is connected between the second switch-side EMI node and the ground node.

7. The power converter system of claim 6, wherein the first connection node is connected to a filter node that is connected to the filter inductor and to the filter capacitor, and wherein the second connection node is connected to the negative DC node.

8. The power converter system of claim 1, wherein the EMI filter is a switch-side EMI filter that is connected across the connection nodes, and the variable-frequency power converter further comprises a DC-side EMI filter that is connected across the DC bus, the DC-side EMI filter comprising: a first DC-side EMI inductor, a first DC-side capacitor, and a second DC-side capacitor, wherein the first and second DC-side capacitors are connected at a ground node.

9. The power converter system of claim 1, wherein the variable-frequency power converter is a three-phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three- phase power converter, the three-phase power converter further comprising: a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.-64-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030310. The power converter system of claim 9, wherein the EMI filter is a DC-side EMI filter, and wherein the variable-frequency power converter further comprise: a three-phase switch-side AC filter connected between the first, second, and third AC connection nodes and EMI AC output nodes, the three-phase switch-side AC filter comprising: a first capacitive stage; a first inductive stage; a second capacitive stage; and a second inductive stage.

11. The power converter system of claim 10, wherein: the first capacitive stage includes a first A-phase capacitor connected to the first AC connection node, a first B-phase capacitor connected to the second AC connection node, and a first C-phase capacitor connected to the third AC connection node, wherein the first A-phase, B-phase, and C-phase capacitors are each also connected to a first common node; the first inductive stage includes a first A-phase inductor connected to the first AC connection node, a first B-phase inductor connected to the second AC connection node, and a first C-phase inductor connected to the third AC connection node; the second capacitive stage includes a second A-phase capacitor connected to the first A- phase inductor, a second B-phase capacitor connected to the first B-phase inductor, a second C- phase capacitor connected to the first C-phase inductor, and a common capacitor coupled between ground and a second common node connecting the second A-phase, B-phase, and C-phase capacitors together; and the second inductive stage includes a second A-phase inductor connected to the first A- phase inductor, a second B-phase inductor connected to the first B-phase inductor, and a second C-phase inductor connected to the first C-phase inductor.

12. The power converter system of claim 1, wherein, to control the variable-frequency power converter to convert power, the control system is configured to: determine at least one electrical operational characteristic for the variable-frequency power converter;-65-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 determine a duty cycle and a switching frequency based on the at least one electrical operational characteristic; and drive the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency.

13. The power converter system of claim 1, wherein the control system is further configured to: determine PWM operational parameters for a PWM control signal; generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

14. A method of converting power, the method comprising: determining, by a control system, at least one electrical operational characteristic for a variable-frequency power converter, the variable-frequency power converter including: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, a DC link capacitor connected across the DC bus, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; determining, by the control system, a duty cycle and a switching frequency based on the at least one electrical operational characteristic; driving the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency; and filtering, by an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, power at the DC voltage section or at the switch-side connection, the EMI-66-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 filter including an EMT inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.

15. The method of claim 14, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein the filtering, by the EMI filter, includes filtering input DC power at the DC voltage section that is for receipt by the variable-frequency power converter.

16. The method of claim 14, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein the filtering, by the EMI filter, includes filtering output DC power at the DC voltage section that is output by the variable-frequency power converter.

17. The method of claim 14, wherein the EMI filter is a switch-side EMI filter connected across the connection nodes, and wherein the filtering, by the EMI filter, includes filtering input AC power at the switch-side section that is for receipt by the variable-frequency power converter.

18. The method of claim 14, wherein the EMI filter is a switch-side EMI filter connected across the connection nodes, and wherein the filtering, by the EMI filter, includes filtering output AC power at the switch-side section that is output by the variable-frequency power converter.

19. The method of claim 14, wherein the EMI filter is a DC-side EMI filter connected across the DC bus, and wherein the filtering, by the EMI filter, includes filtering DC power at the DC voltage section, the method further comprising: filtering, by a switch-side EMI filter connected to the connection nodes, power at the switch-side connection.

20. The method of claim 19, wherein the switch-side EMI filter includes a switch-side EMI inductor, a first switch-side capacitor, and a second switch-side capacitor, wherein the first and second switch-side capacitor are connected at the ground node.

21. The method of claim 19,-67-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 wherein the variable-frequency power converter is a three-phase power converter, the halfbridge circuit is a first half-bridge circuit corresponding to a first phase of the three-phase power converter and the three-phase power converter further comprises a second half-bridge circuit corresponding to a second phase of the three-phase power converter and a third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes, and wherein the switch-side EMI filter is a three-phase switch-side AC filter connected between the first, second, and third AC connection nodes and EMI AC output nodes.

22. The method of claim 14, further comprising: determining PWM operational parameters for a PWM control signal; generating a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and controlling the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.-68-QB\175073.00303\98524560.2Attomey Docket No.: 175073.0030323. A non-transitory computer readable medium comprising instructions stored thereon that, when executed by a computer, control the computer to: sweep control signals that drive a variable-frequency converter circuit to drive the variablefrequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different combinations of duty cycles and switching frequencies; determine a setpoint of the range of setpoints that results in peak electromagnetic interference (EMI) by the variable-frequency converter circuit; generate filter component values for an EMI filter of the variable-frequency converter based on the setpoint determined to result in peak EMI; and provide a modified variable-frequency converter circuit having the EMI filter with the filter components values.

24. The computer readable medium of claim 23, where the instructions, when executed by a computer, further control the computer to: sweep further control signals that drive the modified variable-frequency converter circuit over at least a subset of the range of setpoints; and validate that resulting EMI from the modified variable-frequency converter circuit from sweeping the further control signals is below one or more EMI limits.

25. The computer readable medium of claim 23, where the instructions, when executed by a computer, further control the computer to: capture, while sweeping the control signals, electrical characteristic data of the variablefrequency converter circuit that is indicative of EMI being produced by the variable-frequency converter circuit.

26. The computer readable medium of claim 25, wherein to determine the setpoint of the range of setpoints that results in peak EMI, the instructions, when executed by a computer, control the computer to: identifying, for each setpoint of the range of setpoints, a peak EMI value;-69-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 determining a largest value from the peak EMI values and a corresponding setpoint that corresponds to the largest value; and identifying the setpoint of the range of setpoints that results in peak EMI as the corresponding setpoint that corresponds to the largest value.

27. The computer readable medium of claim 25, wherein to determine the setpoint of the range of setpoints that results in peak EMI, the instructions, when executed by a computer, control the computer to: determine a largest LC product for the range of setpoints, wherein the largest LC product corresponds to the setpoint of the range of setpoints that results in peak EMI and corresponds to a size of the EMI filter to attenuate the peak EMI being produced by the variable-frequency converter circuit at the setpoint.

28. The computer readable medium of claim 27, wherein, to determine the largest LC product for the range of setpoints, the instructions, when executed by a computer, control the computer to: calculate an attenuation value for each setpoint of the range of setpoints; calculate, for each setpoint of at least a subset of the range setpoints, a cutoff frequency based on the attenuation value; calculate, for each setpoint of the at least a subset of the range of setpoints, an LC product based on the cutoff frequency; and identify a largest of the LC products calculated as the largest LC product.

29. The computer readable medium of claim 28, wherein each setpoint of the at least a subset of the range of setpoints corresponds to a respective bin of a plurality of bins, and wherein each bin of the plurality of bins corresponds to a distinct frequency range and EMI limit.

30. The computer readable medium of claim 23, wherein the modified variable-frequency converter circuit includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node; a switch-side section including connection nodes;-70-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 a DC link capacitor connected across the DC bus; and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC fdter comprising a fdter inductor and a filter capacitor.

31. The computer readable medium of claim 30, wherein the EMI filter is a DC-side EMI filter connected across the DC bus or a switch-side EMI filter connected to the connection nodes, wherein the EMI filter includes an EMI inductor, a first capacitor, and a second capacitor, and wherein the first and second capacitor are connected at a ground node.

32. The computer readable medium of claim 30, where the instructions, when executed by a computer, further control the computer to: determine at least one electrical operational characteristic for the modified variablefrequency converter circuit; determine a duty cycle and a switching frequency based on the at least one electrical operational characteristic; and drive the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency to control the modified variable-frequency converter circuit to convert power.

33. The computer readable medium of claim 30, where the instructions, when executed by a computer, further control the computer to: determine PWM operational parameters for a PWM control signal; generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the modified variable-frequency converter circuit are within a defined range; and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.-71-QB\175073.00303\98524560.2Attomey Docket No.: 175073.0030334. A method comprising, sweeping control signals that drive a variable-frequency converter circuit to drive the variable-frequency converter circuit over a range of setpoints, with each setpoint corresponding to control signals having a duty cycle and switching frequency combination of a plurality of different combinations of duty cycles and switching frequencies; determining a setpoint of the range of setpoints that results in peak electromagnetic interference (EMI) by the variable-frequency converter circuit; generating fdter component values for an EMI filter of the variable-frequency converter based on the setpoint determined to result in peak EMI; and providing a modified variable-frequency converter circuit having the EMI filter with the filter components values.

35. The method of claim 34, further comprising: sweeping further control signals that drive the modified variable-frequency converter circuit over at least a subset of the range of setpoints; and validating that resulting EMI from the modified variable-frequency converter circuit from sweeping the further control signals is below one or more EMI limits.

36. The method of claim 34, further comprising: capturing, while sweeping the control signals, electrical characteristic data of the variablefrequency converter circuit that is indicative of EMI being produced by the variable-frequency converter circuit.

37. The method of claim 36, wherein determining the setpoint of the range of setpoints that results in peak EMI comprises: identifying, for each setpoint of the range of setpoints, a peak EMI value; determining a largest value from the peak EMI values and a corresponding setpoint that corresponds to the largest value; and identifying the setpoint of the range of setpoints that results in peak EMI as the corresponding setpoint that corresponds to the largest value.-72-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030338. The method of claim 36, wherein determining the setpoint of the range of setpoints that results in peak EMI comprises: determining a largest LC product for the range of setpoints, wherein the largest LC product corresponds to the setpoint of the range of setpoints that results in peak EMI and corresponds to a size of the EMI filter to attenuate the peak EMI being produced by the variable-frequency converter circuit at the setpoint.

39. The method of claim 38, wherein determining the largest LC product for the range of setpoints comprises: calculating an attenuation value for each setpoint of the range of setpoints; calculating, for each setpoint of at least a subset of the range setpoints, a cutoff frequency based on the attenuation value; calculating, for each setpoint of the at least a subset of the range of setpoints, an LC product based on the cutoff frequency; and identifying a largest of the LC products calculated as the largest LC product.

40. The method of claim 39, wherein each setpoint of the at least a subset of the range of setpoints corresponds to a respective bin of a plurality of bins, and wherein each bin of the plurality of bins corresponds to a distinct frequency range and EMI limit.

41. The method of claim 34, wherein the modified variable-frequency converter circuit includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node; a switch-side section including connection nodes; a DC link capacitor connected across the DC bus; and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor.-73-QB\175073.00303\98524560.2Attomey Docket No.: 175073.0030342. The method of claim 41, wherein the EMI filter is a DC-side EMI filter connected across the DC bus or a switch-side EMI filter connected to the connection nodes, wherein the EMI filter includes an EMI inductor, a first capacitor, and a second capacitor, and wherein the first and second capacitor are connected at a ground node.

43. The method of claim 41, further comprising: determining at least one electrical operational characteristic for the modified variablefrequency converter circuit; determining a duty cycle and a switching frequency based on the at least one electrical operational characteristic; and driving the power switching elements of the half-bridge circuit with control signaling having the duty cycle and the switching frequency to control the modified variable-frequency converter circuit to convert power.

44. The method of claim 41, further comprising: determining PWM operational parameters for a PWM control signal; generating a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the modified variable-frequency converter circuit are within a defined range; and controlling the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.-74-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030345. A power converter system comprising: a variable-frequency power converter with a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, and a switch-side section including connection nodes, the power converter including: a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element, and an LC filter comprising a filter inductor and a filter capacitor; and a control system coupled to the variable-frequency power converter, the control system is configured to: determine PWM operational parameters for a PWM control signal, generate a PWM control signal modification for the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range, and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

46. The power converter system of claim 45, wherein the control system is further configured to: determine the one or more converter system characteristics of the variable-frequency power converter, and determine, in response to the one or more converter system characteristics being within the defined range, to generate the PWM control signal modification to the PWM control signal.

47. The power converter system of claim 46, wherein the one or more converter system characteristics is a switching frequency of the PWM operational parameters, and wherein the defined range is a frequency range for controlling switching of the power switching elements that corresponds to an increase in electromagnetic interference.

48. The power converter system of claim 46, wherein the defined range for the one or more converter system characteristics corresponds to an increase in leakage current.-75-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030349. The power converter system of claim 45, wherein the PWM operational parameters for the PWM control signal are a duty cycle and a switching frequency.

50. The power converter system of claim 49, wherein, to determine the switching frequency, the control system is configured to select the switching frequency to ensure soft switching of the power switching elements.

51. The power converter system of claim 49, wherein the one or more converter system characteristics for the variable-frequency power converter include one or more of a switching frequency, a duty cycle, a change in switching frequency, an output current setpoint of the variablefrequency power converter, an output voltage setpoint of the variable-frequency power converter, an output current of the variable-frequency power converter, an output voltage of the variablefrequency power converter, an input current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an output current ramp-up, an output voltage ramp-up, an operational mode of the variable-frequency power converter, an inductor value of the filter inductor, or a capacitor value of the filter capacitor.

52. The power converter system of claim 45, wherein the PWM control signal modification is at least one of jitter applied to the PWM control signal or a switching frequency offset applied to the PWM control signal.

53. The power converter system of claim 45, further comprising: a DC link capacitor of the variable-frequency power converter that is coupled across the DC bus; and an electromagnetic interference (EMI) filter connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.-76-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030354. The power converter system of claim 45, wherein the variable-frequency power converter is a three-phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three- phase power converter, the three-phase power converter further comprising: a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.

55. The power converter system of claim 54, wherein the PWM control signal and the modified PWM control signal are for the first half-bridge circuit, and wherein the control system is further configured to: determine second PWM operational parameters for a second PWM control signal and third PWM operational parameters for a third PWM control signal, generate a second PWM control signal modification to the second PWM control signal when the one or more converter system characteristics of the variable-frequency power converter are within the defined range, control the second power switching elements with a second modified PWM control signal, wherein the second modified PWM control signal results from the second PWM control signal modification to the second PWM control signal, and control the third power switching elements with a third modified PWM control signal, wherein the third modified PWM control signal results from the third PWM control signal modification to the third PWM control signal.

56. A method for power conversion, the method comprising:-77-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 determining, by a control system, PWM operational parameters for a PWM control signal for controlling a variable-frequency power converter, wherein the variable-frequency power converter includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, an LC fdter comprising a fdter inductor and a fdter capacitor, and a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element; generating, by the control system, a PWM control signal modification to the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and controlling, by the control system, the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

57. The method of claim 56, further comprising: determining the one or more converter system characteristics of the variable-frequency power converter, and determining, in response to the one or more converter system characteristics being within the defined range, to generate the PWM control signal modification to the PWM control signal.

58. The method of claim 57, wherein the one or more converter system characteristics is a switching frequency of the PWM operational parameters, and wherein the defined range is a frequency range for controlling switching of the power switching elements that corresponds to an increase in electromagnetic interference.

59. The method of claim 57, wherein the defined range for the one or more converter system characteristics corresponds to an increase in leakage current.-78-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030360. The method of claim 56, wherein the PWM operational parameters for the PWM control signal are a duty cycle and a switching frequency.

61. The method of claim 60, wherein determining the switching frequency comprises: selecting the switching frequency to ensure soft switching of the power switching elements.

62. The method of claim 56, wherein the one or more converter system characteristics for the variable-frequency power converter include one or more of a switching frequency, a duty cycle, a change in switching frequency, an output current setpoint of the variable-frequency power converter, an output voltage setpoint of the variable-frequency power converter, an output current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an input current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an output current ramp-up, an output voltage ramp-up, an operational mode of the variable-frequency power converter, an inductor value of the filter inductor, or a capacitor value of the filter capacitor.

63. The method of claim 56, wherein the PWM control signal modification is at least one of jitter applied to the PWM control signal or a switching frequency offset applied to the PWM control signal.

64. The method of claim 56, wherein a DC link capacitor of the variable-frequency power converter is coupled across the DC bus; and an electromagnetic interference (EMI) filter is connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.

65. The method of claim 56, wherein the variable-frequency power converter is a three-phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three-phase power converter, the three-phase power converter further comprising:-79-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.

66. The method of claim 65, wherein the PWM control signal and the modified PWM control signal are for the first half-bridge circuit, and method further comprising: determining second PWM operational parameters for a second PWM control signal and third PWM operational parameters for a third PWM control signal, generating a second PWM control signal modification to the second PWM control signal when the one or more converter system characteristics of the variable-frequency power converter are within the defined range, controlling the second power switching elements with a second modified PWM control signal, wherein the second modified PWM control signal results from the second PWM control signal modification to the second PWM control signal, and controlling the third power switching elements with a third modified PWM control signal, wherein the third modified PWM control signal results from the third PWM control signal modification to the third PWM control signal.

67. A non-transitory computer readable medium comprising instructions stored thereon that, when executed by a computer, control the computer to: determine PWM operational parameters for a PWM control signal for controlling a variable-frequency power converter, wherein the variable-frequency power converter includes: a direct current (DC) voltage section including a DC bus with a positive DC node and a negative DC node, a switch-side section including connection nodes, an LC filter comprising a filter inductor and a filter capacitor, and-80-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 a half-bridge circuit including: power switching elements including an upper power switching element and a lower power switching element; generate a PWM control signal modification to the PWM control signal when one or more converter system characteristics of the variable-frequency power converter are within a defined range; and control the power switching elements with a modified PWM control signal, wherein the modified PWM control signal results from the PWM control signal modification to the PWM control signal.

68. The non-transitory computer readable medium of claim 67, further comprising instructions stored thereon that, when executed by the computer, control the computer to: determine the one or more converter system characteristics of the variable-frequency power converter, and determine, in response to the one or more converter system characteristics being within the defined range, to generate the PWM control signal modification to the PWM control signal.

69. The non-transitory computer readable medium of claim 68, wherein the one or more converter system characteristics is a switching frequency of the PWM operational parameters, and wherein the defined range is a frequency range for controlling switching of the power switching elements that corresponds to an increase in electromagnetic interference.

70. The non-transitory computer readable medium of claim 68, wherein the defined range for the one or more converter system characteristics corresponds to an increase in leakage current.

71. The non-transitory computer readable medium of claim 67, wherein the PWM operational parameters for the PWM control signal are a duty cycle and a switching frequency.-81-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.0030372. The non-transitory computer readable medium of claim 71, wherein, to determine the switching frequency the instructions, when executed by the computer, control the computer to: select the switching frequency to ensure soft switching of the power switching elements.

73. The non-transitory computer readable medium of claim 67, wherein the one or more converter system characteristics for the variable-frequency power converter include one or more of a switching frequency, a duty cycle, a change in switching frequency, an output current setpoint of the variable-frequency power converter, an output voltage setpoint of the variable-frequency power converter, an output current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an input current of the variable-frequency power converter, an output voltage of the variable-frequency power converter, an output current ramp- up, an output voltage ramp-up, an operational mode of the variable-frequency power converter, an inductor value of the fdter inductor, or a capacitor value of the filter capacitor.

74. The non-transitory computer readable medium of claim 67, wherein the PWM control signal modification is at least one of jitter applied to the PWM control signal or a switching frequency offset applied to the PWM control signal.

75. The non-transitory computer readable medium of claim 67, wherein a DC link capacitor of the variable-frequency power converter is coupled across the DC bus; and an electromagnetic interference (EMI) filter is connected across the DC bus or the connection nodes, the EMI filter including an EMI inductor, a first capacitor, and a second capacitor, wherein the first and second capacitor are connected at a ground node.

76. The non-transitory computer readable medium of claim 67, wherein the variable-frequency power converter is a three-phase power converter, the half-bridge circuit is a first half-bridge circuit, and the LC filter is a first LC filter, wherein the first half-bridge circuit corresponds to a first phase of the three-phase power converter, the three-phase power converter further comprising:-82-QB\ 175073.00303198524560.2Attomey Docket No.: 175073.00303 a second half-bridge circuit including second power switching elements and a second LC filter, the second half-bridge circuit corresponding to a second phase of the three-phase power converter; and a third half-bridge circuit including third power switching elements and a third LC filter, the third half-bridge circuit corresponding to a third phase of the three-phase power converter, wherein the first, second, and third half-bridge circuits are connected in parallel across the DC bus and include a first, second, and third AC connection node, respectively, of the connection nodes.

77. The non-transitory computer readable medium of claim 76, wherein the PWM control signal and the modified PWM control signal are for the first half-bridge circuit, and wherein the non- transitory computer readable medium further stores instructions that, when executed by the computer, control the computer to: determine second PWM operational parameters for a second PWM control signal and third PWM operational parameters for a third PWM control signal, generate a second PWM control signal modification to the second PWM control signal when the one or more converter system characteristics of the variable-frequency power converter are within the defined range, control the second power switching elements with a second modified PWM control signal, wherein the second modified PWM control signal results from the second PWM control signal modification to the second PWM control signal, and control the third power switching elements with a third modified PWM control signal, wherein the third modified PWM control signal results from the third PWM control signal modification to the third PWM control signal.-83-QB\ 175073.00303198524560.2

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