System and method for power conversion using an LC filter having an inductor with embedded windings - Patents.com

Abstract

An implementation is disclosed that includes a non-isolated power converter system with a filter including an inductor and a capacitor. The inductor of the filter has a core portion and a winding portion. The core portion can include different shaped core structures. The winding portion includes a winding embedded in a printed circuit board. The printed circuit board winding can include Litz wire, and the printed circuit board has one or more of a controller or power switching elements located thereon.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 226,136, filed July 27, 2021, U.S. Provisional Application No. 63 / 242,840, filed September 10, 2021, U.S. Provisional Application No. 63 / 345,896, filed May 25, 2022, U.S. Provisional Application No. 63 / 351,768, filed June 13, 2022, U.S. Provisional Application No. 63 / 226,059, filed July 27, 2021, U.S. Provisional Application No. 63 / 270,311, filed October 21, 2021, and U.S. Provisional Application No. 63 / 319,122, filed March 11, 2022, each of which is incorporated by reference in its entirety herein.

[0002] STATEMENT REGARDING FEDERALLY FUNDED RESEARCH This invention was made with Government support under 1653574 awarded by the National Science Foundation. The Government has certain rights in this invention. [Background technology]

[0003] Various types of power converters are manufactured and used in many industries and situations. Exemplary power converters include alternating current (AC) to direct current (DC) rectifiers, DC-AC inverters, and DC-DC converters. An AC-DC rectifier, also called an AC / DC rectifier, converts AC power to DC power. A DC-AC inverter, also called a DC / AC inverter, converts DC power to AC power. Power converters can be used for a variety of purposes, such as rectifying AC power from an AC grid source into DC power for charging a battery, or converting DC power from a battery back to AC power to drive a motor or to supply AC power to an AC grid. Additionally, power converters can be used in or connected to electric vehicles, engine generators, solar panels, and the like in a variety of situations. Summary of the Invention

[0004] A power converter can be described in terms of power conversion efficiency, power density, and cost, among other characteristics. In general, it is desirable to have a power converter that has higher power efficiency, higher power density, and lower cost. A highly efficient power converter can convert power (e.g., AC to DC, DC to AC, and / or DC to DC) without significant energy loss. A less efficient power converter experiences higher energy losses during power conversion. Such energy losses may manifest, for example, as heat generated by the power converter while converting power. The power efficiency of a power converter, inductor, or other electronic component is expressed as a percentage between 0 and 100% and is expressed by the formula:

number

number

[0005] Energy costs, including monetary and environmental costs, continue to be a significant factor across many industries that incorporate power converters. Thus, even small increases in the power efficiency of a power converter (e.g., of a tenth of a percent) are significant and highly desirable. Similarly, reductions in materials and size of power converters are significant and highly desirable, allowing for reductions in the cost and physical space required to house the power converter in systems that incorporate the power converter.

[0006] In a power converter, the inductor that is part of the LC filter may account for a significant portion of the total power loss of the converter. For high power applications, high frequency power converters with soft switching capabilities, system efficiency may be highly related to the electromagnetic performance of the inductor. Furthermore, the volume of the inductor of the LC filter may affect the power density of the power converter. Effective design of the inductor for soft switching may contribute to higher efficiency, higher power density, and lower cost of the power converter. Some examples of LC filters and inductors of LC filters described herein provide one or more advantages such as reduced cost, improved voltage regulation, reduced power dissipation, improved ability to withstand heavy load currents, lower ripple factor, electromagnetic interference (EMI) reducing filter, filtering of high power signals, and reducing or eliminating ventilation due to less heat generated in the inductor.

[0007] In one embodiment, a non-isolated power converter system includes a power converter including a power switching element. A controller driving the power switching element to convert a received power and output a converted power. The controller is configured to drive the power switching element using variable frequency soft switching (VFSS). A filter including an inductor and a capacitor is coupled to a first side of the power converter to filter a power signal at the first side of the power converter. The signal received by the filter has a current ripple of at least 200% peak-to-peak ripple relative to a local average current. The inductor of the filter has a core portion and a winding portion. The winding portion includes a winding that is embedded in a printed circuit board.

[0008] In one embodiment, an inductor for a filter in a non-isolated power converter system comprises a core portion and a winding portion, the winding portion forming the inductor with the core portion. The winding portion includes a winding embedded in a printed circuit board having a first terminal and a second terminal. The winding is embedded in the printed circuit board to form a Litz PCB including multiple layers of parallel strands in which the winding is routed within the printed circuit board.

[0009] In one embodiment, an inductor for a filter in a non-isolated power converter system includes a winding portion including a winding embedded in a printed circuit board, the winding forming a conductor loop including a first terminal and a second terminal. A core portion forms the inductor with the winding portion, the core portion having a first core portion and a second core portion on opposite sides of the winding portion. The first core portion and the second core portion have a plane facing the conductor loop and generally parallel to the printed circuit board.

[0010] In one embodiment, an inductor for a filter in a non-isolated power converter system includes a winding portion including a winding embedded in a printed circuit board, the winding forming a conductor loop including a first terminal and a second terminal. A core portion forms the inductor with the winding portion, the core portion including a first core portion facing the ambient air portion. The first core portion includes a base portion and three legs extending from the base portion, and a middle leg of the three legs extends through an opening defined by the conductor loop.

[0011] In one embodiment, the non-isolated power converter system includes a power converter including a power switching element, and a controller configured to drive the power switching element to convert received power and output the converted power. The filter includes an inductor and a capacitor, and the filter is coupled to a first side of the power converter to filter the power signal at the first side of the power converter. The inductor further includes a core portion and a winding portion. The printed circuit board includes an embedded winding portion, and the one or more controllers or one or more of the power switching elements are located on the printed circuit board.

[0012] The above and other aspects and advantages of the present disclosure will become apparent from the following description. In the description, reference is made to the accompanying drawings, which form a part of this specification and show one or more embodiments by way of example. However, these embodiments do not necessarily represent the full scope of the invention, and therefore, reference should be made to the claims and this specification to interpret the scope of the invention. In the following description, like reference numerals are used to refer to like parts from figure to figure. [Brief description of the drawings]

[0013] [Figure 1] 1 illustrates a power converter system according to some embodiments. [Diagram 2] 1 illustrates a modified half-bridge converter circuit according to some embodiments. [Diagram 3] 1 illustrates a three-phase DC / AC application with an LC filter according to some embodiments. [Figure 4] 1 illustrates timing diagrams and boundary conditions for soft switching according to some embodiments. [Diagram 5] FIG. 2 illustrates a control diagram for controlling a pair of switching elements of a power converter in accordance with some embodiments. [Figure 6] 4 illustrates another control diagram for controlling a pair of switching elements of a power converter in accordance with some embodiments. [Figure 7A] FIG. 2 shows an isometric view of an EE core inductor with copper wire windings. [Figure 7B] FIG. 1 shows a perspective view of an EE core inductor with windings embedded in a printed circuit board. [Figure 8A] FIG. 1 shows an isometric view of an EI core inductor with windings embedded in a printed circuit board. [Figure 8B] FIG. 1 shows a perspective view of an EI core inductor with windings embedded in a printed circuit board. [Figure 9A] FIG. 1 shows an isometric view of an EA core inductor with windings embedded in a printed circuit board. [Figure 9B]FIG. 1 shows a perspective view of an EA core inductor with windings embedded in a printed circuit board. [Figure 10A] FIG. 1 shows an isometric view of an II core inductor with windings embedded in a printed circuit board. [Figure 10B] FIG. 1 shows a perspective view of a II core inductor with windings embedded in a printed circuit board. [Figure 11A] 1 shows an isometric view of the II core. [Figure 11B] An isometric view of the EA core is shown. [Figure 12] Included is a plan view of a printed circuit board. [Figure 13A] FIG. 1 shows a top perspective view of a printed circuit board with embedded solid windings. [Figure 13B] FIG. 1 shows a top perspective view of a Litz winding embedded printed circuit board. [Figure 14] 1 shows an isometric view of a Litz winding. [Figure 15] 15 shows an enlarged portion of the Litz winding of FIG. 14. [Figure 16] FIG. 1 shows an isometric view of a Litz winding with multiple layers. [Figure 17] 1 shows a plot of resistivity versus frequency as a function of PCB winding type and number of PCB windings. [Figure 18] 1 shows a plot of inductor loss versus volume comparison as a function of core type, winding type, and number of windings. [Figure 19] 1 shows a comparative plot of inductor loss versus cost as a function of core type, winding type, and number of windings. [Figure 20] 1 shows a buried winding portion of an inductor with one or more controllers or one or more power switching elements located within a single printed circuit board. [Figure 21] 1 illustrates a process for power conversion according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] One or more embodiments are described and illustrated in the following description and the accompanying drawings. These embodiments are not limited to the specific details provided herein and may be modified in various ways. Furthermore, there may be other embodiments not described herein. Also, functions performed by multiple components may be integrated and performed by a single component. Similarly, functions described herein as being performed by one component may be distributed and performed by multiple components. Furthermore, components described as performing a particular function may also perform additional functions not described herein. For example, a device or structure that is "configured" in a particular way may be configured in at least that way, but may also be configured in other ways not recited.

[0015] As used in this application, "non-transitory computer-readable medium" includes all computer-readable media, but not consisting of a transitory propagating signal. Thus, non-transitory computer-readable media can include, for example, hard disks, CD-ROMs, optical storage devices, magnetic storage devices, Read Only Memory (ROM), Random Access Memory (RAM), register memory, processor cache, or any combination thereof.

[0016] Furthermore, the phrases and terms used herein are for purposes of explanation and should not be considered 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. Furthermore, the terms "connected" and "coupled" are used broadly and include both direct and indirect connections and couplings and can refer to physical or electrical connections or couplings. Furthermore, the step "and / or" used in conjunction with two or more items is intended to cover the items individually and both items together. For example, "a and / or b" is intended to cover a (and not b), b (and not a), and a and b.

[0017] Disclosed herein are systems and methods for power converters that can provide, among other advantages, power conversion with increased power efficiency, increased power density, and / or reduced cost.

[0018] I. Power Converter Systems 1 illustrates a power converter system 100 according to some embodiments. The power converter system 100 includes an electronic controller 105, a first load / source 110, a power converter 115, an LC filter 120, a contactor 125, a second source / load 130, a third source / load 135, and one or more sensors 140.

[0019] In operation, generally, the electronic controller 105 controls the power switching elements of the power converter 115 with high frequency control signals to convert power either (i) from the first load / power source 110, acting as a power source, to either the second power source / load 130 or the third power source / load 135, acting as a load (depending on the state of the contactor 125), or (ii) from the second power source / load 130 or the third power source / load 135, acting as a power source (depending on the state of the contactor 125), to the first load / power source 110, acting as a load. Thus, when the first load / power source 110 is acting as a power source for the power converter 115, the second power source / load 130 (or the third power source / load 135, depending on the state of the contactor 125) is acting as a load for the power converter 115. Conversely, when the first load / source 110 is acting as a load for the power converter 115, the second source / load 130 (or the third source / load 135, depending on the state of the contactor 125) is acting as a source for the power converter 115.

[0020] The first load / source 110 may be a direct current (DC) load, a DC source, or both a DC load and a DC source (i.e., depending on the mode of the power converter 115, it functions as a DC source in some cases and as a DC load in other cases). In some examples, the first load / source 110 is a battery. The second source / load 130 and the third source / load 135 may be a DC load, a DC source, both a DC load and a DC source, an AC load, an AC source, or both an AC load and an AC source (i.e., depending on the mode of the power converter 115, it functions as an AC source in some cases and as an AC load in other cases). In some examples, the second source / load 130 is an electric motor and the third source / load 135 is an AC generator or an AC power grid. In some examples, the second source / load 130 and the third source / load 135 are both DC batteries. In some examples of the system 100 , the second power source / load 130 is connected to the LC filter 120 without an intermediate contactor 125 , and the contactor 125 and the third power source / load 135 are not present in the system 100 .

[0021] A first load / source 110 is coupled to the power converter 115 on a first side of the power converter 115, and a second source / load 130 (or a third source / load 135, depending on the state of the contactor 125) is coupled to the power converter 115 on a second side of the power converter 115. The first side may be referred to as the input side or output side of the power converter 115, depending on the mode of the power converter, and may be referred to as the DC side of the power converter 115. The second side may be referred to as the input side or output side of the power converter, depending on the mode of the power converter, the DC side or AC side of the power converter 115, or an interface side, depending on the power type of the second and / or third source / load 130, 135. 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.

[0022] In some embodiments, power converter 115 operates at high DC voltage levels. For example, during operation, the DC side of power converter 115 has a DC voltage (e.g., between the input terminals of power converter 115) of at least 200V, at least 600V, at least 800V, at least 1000V, at least 1200V, between 200V and 1200V, between 600V and 1200V, between 800V and 1200V, or another range. Such high DC voltage levels may be desirable in some situations, such as some electric vehicles. For example, some current electric vehicles (e.g., passenger cars and hybrid electric vehicles) operate with a DC bus voltage of about 200V to 400V. This DC bus voltage for passenger electric vehicles may increase in the future. Additionally, some current electric vehicles (e.g., class 4-8, off-road, or other larger electric vehicles) can operate with DC bus voltages in excess of 1000V, but the high DC voltage levels can introduce challenges to typical power converter systems, such as increased leakage currents, increased common mode voltages, and higher rates of change of common mode voltages. When the second or third power source / load is a motor (e.g., a traction motor in an electric vehicle), these challenges can lead to shaft voltages and bearing currents (e.g., from discharge events when lubricant breakdown occurs) that can result in bearing failure. However, embodiments described herein can mitigate such challenges, for example, by variable frequency soft switching, well-designed LC filters, and / or additional capacitors, as described herein. For example, in the context of an electric vehicle, embodiments described herein can reduce bearing currents and shaft voltages by controlling the common mode voltage of the system to remain below a threshold and / or maintaining the change in common mode voltage below a rate of change threshold.

[0023] The sensors 140 may include, for example, one or more current sensors and / or one or more voltage sensors. For example, the sensors 140 may include respective current and / or voltage sensors for monitoring the current and / or voltage of each phase of one or more of the first load / source 110, the second source / load 130, the third source / load 135, the LC filter 120, or the power converter 115. For example, if the LC filter 120 is a three-phase LC filter, the sensors 140 may include at least three current sensors, one for sensing the current of each phase of the three-phase LC filter 120. In some embodiments, additional or fewer sensors 140 are included in the system 100. For example, the sensors 140 may also include one or more vibration sensors, temperature sensors, etc. In some examples, the controller 105 infers or estimates a characteristic (e.g., current or voltage) at one or more nodes of the power converter 114 rather than directly sensing the characteristic.

[0024] 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, a touch screen, a keyboard, etc.) and / or includes or is configured to provide output to one or more outputs (e.g., LEDs, a display screen, a speaker, a haptic generator, etc.). Other electronic devices and / or a user can communicate with system 100, and in particular controller 105, via I / O interface 142.

[0025] The electronic controller 105 comprises an electronic processor 145 and a memory 150. The memory 150 includes one or more of a read-only memory (ROM), a random access memory (RAM), or other non-transitory computer-readable medium. The electronic processor 145 is configured to, among other things, receive instructions and data from the memory 150 and execute the instructions to perform the functions of the controller 105 described herein, including, for example, the processes described below. For example, the memory 150 includes control software. As described in more detail below, in general, the electronic processor 145 can be configured to execute the control software to monitor the system 100 including the power converter 115 (e.g., based on sensor data from the sensor 140), receive commands (e.g., via the input / output interface 142), and drive the power converter 115 (e.g., in accordance with the sensor data and / or commands). In some embodiments, instead of or in addition to executing software from the memory 150 to perform the functions of the controller 105 described herein, the electronic processor 145 includes one or more hardware circuit elements configured to perform some or all of these functions.

[0026] Although the controller 105, the electronic processor 145, and the memory 150 are each shown as a single unit, in some embodiments, one or more of these components are distributed components. For example, in some embodiments, the electronic processor 145 includes one or more microprocessors and / or hardware circuit elements. For example, the controller 105 or the electronic processor 145 can include a processor and a gate driver circuit, where the processor provides a PWM duty cycle and / or frequency to the gate driver circuit, and the gate driver circuit drives the power switching elements according to the PWM duty cycle and / or frequency.

[0027] II. Upper Capacitor for Half-Bridge Switching Converter Topology 2 illustrates an example of a half-bridge converter 200 that can function as the power converter 115 of the system 100 of FIG. 1. As illustrated, the converter 200 includes a DC terminal 220 (also referred to as a DC node, DC link, DC rail, etc.) having a positive DC terminal 222 and a negative DC terminal 224. The converter 200 further includes an interface terminal 225 (also referred to as an interface node) having a positive interface terminal 227 and a negative interface terminal 229. The converter 200 can operate as a bidirectional converter or a unidirectional converter (in either direction), depending on the configuration and control of the system in which it is implemented. Thus, in some examples, the DC terminal 220 can be an input terminal and the interface terminal 225 can be an output terminal (e.g., DC / DC conversion and DC / AC inversion), and in some examples, the DC terminal 220 can be an output terminal and the interface terminal 225 can be an input terminal (e.g., AC / DC rectification). Furthermore, the interface terminal 225 may be an AC input terminal (for example, for AC / DC rectification), an AC output terminal (for example, for a DC / AC inverter), or a DC output terminal (for example, for DC / DC conversion).

[0028] The converter 200 includes a DC link capacitor (C DC 1. The system further includes a high side (upper) power switching element (M1) 235 (also referred to as an upper switch 235), a low side (lower) power switching element (M2) 240 (also referred to as a lower switch 240), a midpoint node 242 connecting the drain terminal of the upper switch 235 and the source terminal of the lower switch 240, and an LC filter 245. The LC filter 245 is an example of the LC filter 120 of the system 100 of FIG.

[0029] The power switching elements 235 and 240 may each be a field effect transistor (FET) having respective gate, source, and drain terminals. The FETs may be, for example, MOSFETs, silicon carbide (SiC) FETs, gallium nitride (GaN) FETs, among other types of FETs.

[0030] The LC filter 245 is made up of a switch-side inductor LF250 and a lower-side capacitor C B 255 and the upper capacitor C A 215. The switch-side inductor LF 250 is coupled between the midpoint node 242 and the filter node 260. For example, a first end of the switch-side inductor LF 250 is coupled to the midpoint node 242, and a second end is coupled to the filter node 260. The lower capacitor CB 255 is coupled between the midpoint node 242 and the negative DC terminal 224. For example, a first end of the lower capacitor CB 255 is coupled to the midpoint node 242, and a second end is coupled to the negative DC terminal 224. The upper capacitor CA 215 is coupled between the midpoint node 242 and the positive DC terminal 222. For example, a first end of the lower capacitor CA 255 is coupled to the midpoint node 242, and a second end is coupled to the positive DC terminal 222.

[0031] In some examples, LC filter 245 is an LCL filter (an LC filter with an additional inductor (L)) in which an additional (interface) inductor is coupled between filter node 260 and the positive interface terminal 227.

[0032] The converter is connected to a drain-source capacitor, C DS 265a and 265b, each coupled across one of the switches 235, 240, respectively. In particular, a first drain-source capacitance 265a is provided across the source terminal 270a and the drain terminal 275a of the upper switch (M1) 235, and a second drain-source capacitance 265b is provided across the source terminal 270b and the drain terminal 275b of the lower switch (M2) 240. DS ) 265a-b are collectively referred to herein as drain-source capacitors (C DS )265.

[0033] The upper capacitor 215 allows the ripple currents at both the input and output nodes (nodes 222, 227) of the converter 200 to be shared. Since the ripple currents on the input and output nodes have some correlation, the differential mode currents at these input and output nodes can be cancelled through this capacitance. This reduction in differential mode currents can result in improved EMI performance and reduced total capacitor ripple current when compared to a typical half-bridge converter (e.g., when the total capacitance between the two converters is held constant). Furthermore, the reduction in total capacitor ripple current can allow for a reduction in capacitor size, for example, when the capacitor ripple current drives the capacitor sizing.

[0034] Drain-source capacitor (C DS ) 265 can slow down the voltage rise during the on-off transitions of switches 235 and 240. This slower voltage rise can in turn reduce the switching losses of switches 235 and 240.

[0035] In some examples of converter 200, the upper capacitor C A 215 and the drain-source capacitor C DS One or both of these are not included in converter 200.

[0036] As previously mentioned, in some examples, power converter 200 can function as power converter 115 of system 100 of FIG. 1. In the context of power converter 115 (and thus power converter 200) implementing an AC / DC rectifier or a DC / AC inverter, power converter 200 is a single-phase power converter 200. In some examples, multiple instances of power converter 200 are paralleled to collectively function as power converter 115 of FIG. 1 to provide single-phase conversion (whether rectification or inversion) or to provide DC / DC power conversion. In some examples, power converter 115 is a multi-phase power converter (e.g., operates with three or more phases of AC power). In such examples, power converter 115 can include multiple instances of power converter 200, each associated with a phase of the AC power, each instance having a shared DC terminal 220, and each instance having an independent V interface 2 and 3. An example of such a power converter is shown in FIG. 3. In some of these examples, multiple instances of power converters 200 are paralleled to collectively provide power conversion for each phase (e.g., two parallel power converters 200 for phase 1, two parallel power converters 200 for phase 2, and two parallel power converters 200 for phase 3). In some examples, the specific number of parallel power converters 200 and the number of phases vary. Either single-phase conversion (whether rectification or inversion) is provided, or DC / DC power conversion is provided.

[0037] Figure 3 shows a multi-phase power converter system 300. The multi-phase converter system 300 includes a multi-phase converter 304 coupled on the DC side to a battery 306 and coupled to an AC grid 302 via an LCL filter 308. The multi-phase converter 304 may function as the power converter 115 of the system 100 of Figure 1, and the LCL filter 308 may function as the LC filter 120 of the system 100 of Figure 1. In operation, the multi-phase converter 300 may function as a DC / AC inverter or an AC / DC rectifier, depending on the power source and the switching of the power switching elements.

[0038] 2. Each instance includes an upper switch 235 and a lower switch 240 with a drain-source capacitor coupled across each of the switches. The multi-phase converter 300 is further coupled to a battery 310 via DC terminals 220 and to the AC grid 302 via interface terminals 225. The multi-phase converter 300 includes three LCL filters 308. Each LCL filter 308 includes components similar to the LC filter 245 of FIG. 2 and includes an interface inductor (LCL) coupled between a filter node 260 and the AC grid 302. fg That is, the LCL filter 308 includes a switch-side inductor 250 (L fs,a , L fs,b , or L fs,c ) and the lower capacitor 255 (C f,a , Cf,b , and C f,c ), and upper capacitor 215 (C f,a , C f,b , or C f,c A switch-side inductor 250 is coupled between the midpoint node 242 and a filter node 260.

[0039] In the illustrated example, the multi-phase converter 300 is coupled to a battery 306 and an AC grid 302. In other examples, the multi-phase converter 300 is coupled to a DC source / load other than the battery 306 (e.g., a capacitor, an ultracapacitor, a DC source from a rectified AC source, etc.) and / or an AC source / load other than the grid 302 (e.g., a three-phase motor, an engine generator, etc.). Additionally, the multi-phase converter 300 includes a drain-source capacitor per switch and an interface inductor 347 per phase, although in some examples one or more of these components are not included. Additionally, in some embodiments, the upper capacitor 215 of each phase is coupled between each filter node 260 and the positive DC node 222 as shown in FIG. 2 (single-phase case).

[0040] III. Variable Frequency Critical Soft Switching In some examples, the half-bridge power converter 200 and / or the multi-phase power converter 300 are driven using a variable frequency critical soft switching (VFCSS) scheme. The VFCSS scheme can provide improved efficiency and reduced filter volume (i.e., improved power density) of the power converter. Soft switching allows for the replacement of turn-on switching losses with turn-off switching losses, which is beneficial because turn-on losses in SiC devices are typically much larger than turn-off losses. This VFCSS technique allows for an increase in switching frequency (e.g., 5 times) and a reduction in inductance (e.g., 20 times) while reducing FET losses, resulting in improved power density and efficiency.

[0041] VFCSS is implemented by varying the switching frequency to achieve a desired inductor ripple current in the LC filter (e.g., in the switch-side inductor 250 of the LC filter 245). The desired inductor ripple current is determined when the valley point of the inductor current is equal to the inductor threshold current I L,thr can be derived to arrive at a given value of I. L,thr is set according to the boundary conditions of the dead time and peak / valley inductor current of inductor 250, which can be derived from the output capacitance of switching elements 235 and 240. d ) and peak-valley inductor current I L,max and I L,minand . The inductor current and dead time values ​​that result in soft switching are identified as the soft turn on switching region or regions, and the inductor current and dead time values ​​that do not result in soft switching are identified as the hard switching region or regions. The soft switching region represents the operating region where there is sufficient time and current to discharge the output capacitance of the power switching element (M1 or M2) before turning on. Analytically, these boundaries are expressed as follows: (1 / 2)I L,max T d ≦Q min ≦0, (1 / 2)I L,min T d ≧Q max ≧0 Here, Q min and Q max is the minimum discharge threshold of the switch output capacitance for soft switching.

[0042] For highly positive values ​​of the DC inductor current, the threshold current level -I L,thr A large current ripple is required to keep the valley inductor current point lower than the threshold current I. The negative inductor current discharges the upper switch output capacitance during the turn-off transition of the lower switch. Similarly, for high negative values ​​of DC inductor current, the peak inductor current point rises above the threshold current I L,thrA large current ripple is also required to ensure that the threshold current is greater than 1 V. Zero voltage switching (ZVS) of the lower switch is achieved if the output capacitance of the lower switch is fully discharged by the positive inductor current during the turn-off transition of the upper switch. In general, to achieve full soft switching over an entire cycle (e.g., an entire grid cycle), the current ripple should be large enough to guarantee a bidirectional inductor current path or the dead time needs to be extended. Since an unnecessarily long dead time can result in distortion, the VFCSS adjusts the switching frequency to maintain critical soft switching over the entire cycle. The VFCSS scheme is implemented to maintain a positive threshold current during the negative part of the cycle and a negative threshold current during the positive part of the cycle. The switching frequency to achieve this for any threshold can be calculated by the following equation:

number

[0043] 5 is a control diagram for controlling a pair of switching elements of a power converter. In particular, the control diagram illustrates an example of a controller 105 implementing an exemplary control scheme for VFCSS control of a power converter 200 including an upper capacitor 215. The controller 105 determines a reference duty cycle (d*) and a reference switching frequency (F SWThe power converter 200 includes a duty cycle generating controller 405 and a frequency generating controller 410, which may be regulators for generating a reference duty cycle (d*), respectively. The duty cycle generating controller 405 may generate a reference duty cycle (d*) based on sensed (or estimated) characteristics of the power converter 200, such as current and / or voltage. For example, the duty cycle generating controller 405 may implement a PID controller or another type of regulator. The frequency generating controller 410 may generate a reference duty cycle (d*) based on the sensed (or estimated) characteristics of the power converter 200 and F SW *Based on the above formula to calculate the reference switching frequency (F SW The gate driver 415 can generate a reference duty ratio (d*) and a reference switching frequency (F*) from the controllers 405 and 410. SW *) based on the received reference values. The gate driver 415 generates a first PWM control signal for the upper switch (M1) 235 and a second PWM control signal for the lower switch (M2) 240 based on the received reference values. For example, the gate driver 415 generates a first PWM control signal having a frequency (FSW) equal to the reference switching frequency and a duty cycle (d1) equal to the reference duty cycle (d*). Similarly, the gate driver 415 generates a first PWM control signal having a frequency (FSW) equal to the reference switching frequency and a duty cycle (d1) equal to the reference duty cycle (d*). SW *) equal to the frequency (f SW ) and 1-d1-(T d / f SW ) and an ON edge of the second PWM control signal occurs at a time T later than an OFF edge of the first PWM control signal. d / 2, and the OFF edge of the second PWM control signal is delayed by a time T d / 2 precedes.

[0044] FIG. 6 is another control diagram for controlling a pair of switching elements of a power converter. In particular, the control diagram shows a more detailed example of a controller 105 implementing the VFCSS control provided with respect to FIG. 5. FIG. 6 is just one example of an implementation of the controller 105 for implementing VFCSS, and in other embodiments, the controller 105 implements VFCSS in other ways. For example, a regulator different from that shown in FIG. 6 can be used to generate the reference duty cycle and reference switching frequency.

[0045] In the example of FIG. 6, the duty cycle generating controller 405 compares a reference output voltage to a sensed output voltage of the converter (e.g., Vo at interface terminal 225) and generates a reference inductor current (I L The two-stage regulator has a first voltage regulation stage that generates a reference inductor current (I L *) to detect the inductor current (I L ) to generate a reference duty cycle (d*).

[0046] In the example of FIG. 6, the frequency generating controller 410 calculates the reference switching frequency (f SW In some examples, the frequency generation controller 410 determines the reference switching frequency (f SW ) and in another example, the input of the frequency generating controller 410 is dynamically calculated to generate the reference switching frequency (f SW A look-up table is provided to map the reference switching frequency (fsw) to a particular value of fsw. The frequency generation controller 410 also includes a frequency limiter stage that limits the reference switching frequency (fsw) to a maximum and minimum value.

[0047] The gate driver 415 is provided with a reference duty ratio (d*) and a reference switching frequency (f SW ) is provided. Gate drivers 415 then generate PWM control signals to drive the power switching elements of power converter 200, as previously described.

[0048] In power converters, inductors account for a significant portion of the total power loss. For high power applications, high frequency power converters with soft switching capabilities, system efficiency can be significantly related to the electromagnetic performance of the inductor. Additionally, the volume of the inductor can affect the power density of the energy conversion system. Effective design of the inductor for soft switching contributes to achieving higher efficiency, higher power density, and lower cost of the power converter. By combining inductor and capacitor components with opposite characteristics, noise can be reduced and specific signals can be identified. Some examples of LC filters described herein provide one or more advantages such as lower cost, improved voltage regulation, lower power consumption, improved ability to withstand heavy load currents, lower ripple factor, filtering of high power signals, and reduction or elimination of ventilation due to less heat generated in the inductor.

[0049] IV. LC filter inductors A conventional inductor has a coil wound around a core. When a current starts to flow through the coil, the coil starts to build up a magnetic field. The electromagnetic storage capacity of a conventional inductor is controlled by the number of coils wound around the core, the iron-based material, the diameter of the coil, and the magnetic wire length of the coil.

[0050] A. LC filter inductor cores 7A and 7B, an "EE" shaped core 700 is shown as a portion of inductor 701 and inductor 702, respectively. Specifically, referring to FIG. 7A, inductor 701 includes a core portion 705 that receives a winding portion 710. The core portions of the various inductors provided herein take on various shapes. Core portion 705 in FIG. 7A includes an "EE" shaped core 700. Winding portion 710 includes a wire inductor 715, which may be a Litz wire or a solid (cross-section) copper wire, wound around the "EE" shaped core 700. The "EE" shaped core 700 includes a first portion 720 and a second portion 725, each portion being "E" shaped with a base 730 having three legs 735 extending away from the base 730. The legs 735 and base 730 may each have an approximately rectangular cuboid shape. The distal ends 740 of the legs 735 of each of the first and second portions 720, 725 are separated by a gap 745 and are disposed across one another, with the bases 730 of the two portions 720, 725 at either end of the "EE" shaped core 700. The middle leg 750 and the outermost leg 755 are parallel to one another, and the thickness of the middle leg 750 may be different than the outermost leg 755.

[0051] As with other cores provided herein, the "EE" core may also be combined with winding portions that include or are formed by PCB windings. With specific reference to FIG. 7B, an inductor 702 is shown having an "EE" shaped core 700 (as the core portion) and PCB windings 760 (as the winding portion). Conductive tape 765 is used to connect the PCB windings 760. The PCB windings 760 include embedded wiring, which will be described in more detail below through FIGS. 11 and 12.

[0052] 8A and 8B, an "EI" shaped core 800 is shown as a portion of inductor 801 and inductor 802, respectively. The "EI" shaped core 800 includes a first portion 805 and a second portion 810. With specific reference to FIG. 8A, an inductor 801 is shown having an "EI" shaped core 800 (as the core portion) and a Litz PCB winding 815 (as the winding portion). The Litz PCB winding 815 is described in more detail below and through FIGS. 14-15. The first portion 805 of the core 800 is shaped like an "E" and includes a base 820 having three legs 825 extending away from the base 820. The second portion 810 is "I" shaped having a rectangular cuboid shape similar to the base 820 of the first portion 805 without the legs 825. The base 820 includes or defines a first surface 830 and a second surface 835. Distal ends 840 of legs 825 of first portion 805 project away from base 820 of first portion 805 toward one surface of second portion 810 (e.g., toward surface 830). First portion 805 and second portion 810 are separated by an air gap 745. Additionally, second portion 810 and base 820 of first portion 805 are parallel and are at opposite ends of the inductor.

[0053] 8B, an inductor 802 is shown having an "EI" shaped core 800 (as the core portion) and PCB windings 850 (as the winding portion). Conductive tape 855 may be used to connect the PCB windings 850. The PCB windings 850 include embedded wiring, which will be described in more detail below through FIGS. 11 and 12.

[0054] 9A and 9B, an "EA" shaped core 900 is shown as a portion of inductor 901 and inductor 902, respectively. Specifically referring to FIG. 9A, an inductor 901 is shown having an "EA" shaped core 900 (as a core portion) and a Litz PCB winding 905 (as a winding portion). The "EA" shaped core 900 includes an "E" shaped first portion 910 having a base 915 with three legs 920 extending away from the base 915. The "EA" shaped core 900 further includes an air portion 925 representing the "A" of the "EA" shaped core 900, opening to a side 930 of the inductor 901. With the three legs 920 extending from the base 915 of the "EA" shaped core 900, the air portion 925 is adjacent to a distal end 935 of the three legs 920 extending from the base 915 and facing the base 915 of the "E" shaped core. A window 940 is formed between the three legs 920. The window receives the PCB winding 905 and, with the height of the legs 920, may define or limit the height of the stacked PCB winding.

[0055] 9B, an inductor 902 having an "EA" shaped core 900 (as the core portion) and a PCB printed inductor 945 (as the PCB portion) are shown. An air gap 745 may exist between each pair of extending legs 920 of the "EA" shaped core 900. The height of the air gap 745 of the "EA" 900 shaped core can be adjusted by changing the leg height LH (or extension length from the base 915) of the legs 920 or by inserting additional layers of PCB printed inductor 945 windings. For example, compared to inductor 902, inductor 901 of FIG. 9A has the smallest air gap because the height of the PCB winding 905 is approximately the same height as the legs 920. This air gap height for both inductors is larger in some instances and smaller in other instances (e.g., based on the height of the legs 920 and the number of PCB layers 905, 945).

[0056] 10A and 10B, a "II" shaped core 1000 is shown as a portion of inductors 1001 and 1002, respectively. Specifically referring to FIG. 10A, an inductor 1001 is shown having a "II" shaped core 1000 (as a core portion) and a Litz PCB winding 1005 (as a winding portion). The "II" shaped core 1000 includes a first portion 1010 and a second portion 1015, each portion being shaped like an "I" having a generally rectangular cuboid shape. The first portion 1010 and the second portion 1015 of the "II" shaped core are spaced apart from each other by an air gap 745. The Litz PCB winding 1005 is sandwiched between the first "I" portion 1010 and the second "I" portion 1015. In this inductor 1001, the core does not have legs inserted or threaded into the winding portion, and the winding portion is not wound around a portion of the core 1000.

[0057] 10B, inductor 1002 includes a "II" shaped core 1000 (as the core portion) with a PCB winding 1025 (as the winding portion) sandwiched between a first portion 1010 and a second portion 1015 of the "II" shaped core 1000 within an air gap 745. Similar to inductor 1001, in inductor 1002, the core does not have legs that are inserted or threaded into the winding portion, and the winding portion is not wound around a portion of the core 1000.

[0058] Different core shapes and compositions offer different advantages and tradeoffs. For example, referring to Figures 7A and 7B, an "EE" shaped core 700 is larger in volume and uses more material than other core shapes (e.g., "EA," "EI," and "II"), increasing the cost and overall size of inductors 701 and 702 that include this core. However, the "EE" shaped core 700 allows for a larger winding height (or window), which allows for more windings that can be stacked in parallel to reduce coil resistance and copper losses.

[0059] Referring to the "II" shaped core 1000 in FIG. 11A, the "II" shaped core 1000 has a smaller volume than other core shapes (e.g., "EA," "EI," and "EE"), resulting in reduced material costs and inductor size. However, the "II" shaped core includes a minimum air gap 745, limiting the number of turns of the winding section (whether winding or laminated PCB). Thus, the number of turns of the winding and the air gap 745 can be carefully designed to support a desired inductance to reduce copper losses. Still referring to FIG. 11A, the air gap 745 between the first "I" shaped section 1110 and the second "I" shaped section 1115 can be determined by the height H of the winding, which can be determined by the number of PCB turns.

[0060] Referring to the "EI" shaped core 800 (of FIGS. 8A and 8B), the "EI" shaped core 800 is a hybrid between the "EE" shaped core 700 and the "II" shaped core 1000 that can be used to reduce volumetric cost (of the "EE" shape) and copper loss (of the "II" shape). The "EI" shaped core 800 allows for stacking of PCB printed windings while offering the advantage of being able to have a larger air gap 745 (and contain more windings) than with the "II" shape.

[0061] Referring to the "EA" shaped core 900 of FIG. 11B, the "EA" shaped core 900 includes an air gap 745 that is limited by an open area 1150 (e.g., an area defined by a plane extending across the distal ends 1160 of the legs 1162) at the top of the "E" shaped core. Thus, stated another way, the air gap 745 is limited by the length of the legs 1162 (or the extension of the legs 1162 from the base 1165). The "E" shaped core 900 defines a magnetic flux path that, at least in some examples, passes through only two window widths (W) at the top of the "E" shaped core 900 to terminate the magnetic flux loop. Thus, in at least some examples, the number of PCB printed windings may not exceed the height H between the distal ends 1160 of the three legs 1162 and the base 1165. In some examples, the air gap 745 in the "EA" shaped core 900 is approximately the same as the width W of the window 940, and the "EA" shaped core 900 uses less magnetic (core) material than the "EE" shape (50% less) and the "EI" shape, thereby reducing the cost and volume of the inductor.

[0062] Although the inductors of Figures 7B-10B are shown having a particular size and number of PCB windings, in some examples the particular size and number of PCB windings may vary. For example, in some examples the inductors of Figures 7B-10B may be provided with more or fewer PCB windings. Additionally, the particular length or spacing between the legs of the "E" shaped base, or the particular length, width, and height of the "I" shaped base of the core may be increased or decreased in some examples.

[0063] B. Winding for LC filter inductors The inductor design of the present disclosure includes a winding portion around one of the aforementioned cores. Unlike conventional inductors that include a wound coil, the present disclosure includes a printed circuit board (PCB) winding, such as the PCB winding 1200 of FIG. 12, that includes a circuit board or substrate 1205 with an embedded inductor winding (not shown in FIG. 12). The circuit board 1205 of the PCB winding 1200 includes or defines an opening 1210 disposed around the center of the PCB winding 1215. For example, in FIG. 12, the opening 1210 is rectangular, but in some examples, it may include a different shape, such as a circle, an oval, or a triangle, or may be absent. Similarly, the peripheral shape of the circuit board 1205 may vary from the rectangle shown in FIG. 12 and may instead be a circle, an oval, a triangle, etc. An inductor that includes a PCB winding 1200 with an embedded winding offers various advantages over conventional wire-wound inductors, including, but not limited to, lower cost, more durable windings, and reduced complexity for mass production.

[0064] 13A and 13B show PCB windings 1300 and 1302, respectively, which may be examples of PCB winding 1200. The embedded windings of PCB windings 1300 and 1302 include a conductive material such as copper, a ferrite material, or another material with similar properties (e.g., low power loss density). The embedded windings may have the following configurations, for example: rectangular foil solid conductor, round wire solid conductor, and round Litz wire conductor.

[0065] The PCB winding 1300 of FIG. 13A can be referred to as a solid PCB winding 1300 including a circuit board 1310 with an embedded solid round wire conductor 1315. The solid round wire conductor 1315 extends in a rectangular spiral 1320 on the circuit board 1310 around an opening 1325 in the circuit board 1310. The number of loops that the solid round wire conductor 1315 traverses on the circuit board 1310 may vary based on inductor design considerations. For example, generally, the more loops, the greater the inductance that the inductor provides. Within the board 1310, the embedded solid wiring conductor 1315 can form multiple loops through one or both of: (i) multiple vertical layers of the circuit board 1310 such that the loops are stacked on top of each other, and (2) forming loops with different diameters within a single layer (e.g., in the case of two loops, the wiring forms an inner loop and an outer loop on a single layer as shown in FIG. 13A).

[0066] The PCB winding 1302 of FIG. 13B may be referred to as a Litz PCB winding 1302. The Litz PCB winding 1302 includes a circuit board 1350 with a Litz conductor 1355 embedded therein. As described further below, the Litz conductor 1355 has similar properties to a Litz wire, which is a wire having multiple parallel strands insulated from each other (e.g., by an insulating sleeve) along the length of the wire. Thus, the conductor 1355 is referred to herein as a Litz wire conductor 1355 or a Litz conductor 1355. The Litz wire conductor 1355 forms a weave pattern 1360 in the circuit board 1350. The Litz wire conductor 1355 and its weave pattern 1360 may extend around an opening 1365 in the circuit board 1350. The size of the openings 1210, 1325, 1365 can be larger than the thickness of the middle leg 750 of the "E" shaped core as shown in Figure 7A so that the middle leg 750 can pass through the openings 1210, 1325, and 1365. The Litz wire conductor 1355 of the Litz PCB winding 1302 can include one or more layers of a weave pattern 1360, for example, as described in more detail below with respect to Figures 14-16.

[0067] The solid PCB winding 1300 and the Litz PCB winding 1302 offer different AC resistances related to the acceptable or desired frequency of current excitation. Higher frequencies result in thinner skin depths, which affect the modified penetration ratio and may affect skin and proximity effect factors. The penetration ratio, switching frequency, and number of turns and / or PCB winding layers affect the resistivity.

[0068] The Litz wire conductor 1355 used in the Litz PCB winding 1302 can reduce and / or eliminate the AC resistance of the inductor compared to the solid round wire conductor 1315 of the solid wiring PCB winding 1300. The Litz wire conductor 1355 can be manufactured by twisting multiple strands of wire to reduce the skin and proximity effects. With respect to the skin effect, each strand has a much smaller cross-sectional area, so the skin thickness is negligible compared to the diameter of the Litz wire conductor 1355. The proximity effect in the Litz conductor 1355 is limited by the evenly distributed strands canceling the magnetic field of the adjacent strands. Thus, the Litz wire conductor 1355 reduces both the skin effect and the proximity effect and reduces AC losses compared to the solid wiring winding, whether it is wound (as in FIG. 7A) or embedded in the solid wiring PCB (as in FIG. 13A). However, the solid wiring PCB winding 1300 can be manufactured with less complexity compared to the Litz PCB winding 1302.

[0069] Referring to FIG. 14, a three-dimensional (3D) routed Litz PCB winding 1400 with a Litz wire conductor 1355 is shown. In FIG. 14, a 3D Litz PCB routing technique is used to provide the Litz wire conductor 1355 with the pattern 1360 described above with respect to FIG. 13B. The pattern 1360 is formed by multiple strands that collectively form the Litz wire conductor 1355. The 3D routed PCB winding 1400 offers advantages such as inherent insulation capability, convenience of assembly, and high window space utilization, and the Litz wire offers advantages such as reduced AC losses, as described above. The 3D Litz PCB routing technique uses a Litz structure of round stranded wire that is embedded and routed through multiple layers of a circuit board 1350 (although the circuit board 1350 is not shown in FIG. 14 to highlight the Litz structure). The 3D Litz PCB is routed taking into account the magnetic field generated by the strands of the Litz conductor 1355. For example, each strand of a Litz conductor in the circuit board 1350 may spiral evenly through all layers of the circuit board 1350 to cancel adjacent magnetic fields of adjacent strands of the Litz conductor 1355. Furthermore, the length of each strand of the Litz conductor 1355 may be substantially the same to avoid non-uniform magnetic fields between different strands.

[0070] 3D Litz PCB routing technology can be extended and applied to various numbers of strands and layers for better emulation of round Litz wire. To route uniformly through multiple layers of PCB, Litz PCB can be configured with six different routing modes including left-right mode, left-right mode, external via up mode, external via down mode, internal via up mode, and internal via down mode. Left-right mode is a trace (strand) routed directly to the left and right of a copper layer. External via up mode and external via down mode are distributed on both sides of the circuit board edge to connect between adjacent copper layers. When the PCB routing method includes more than four layers, internal via up and internal via down modes are added to the 3D Litz PCB routing technology. Internal via up mode and internal via down mode are distributed in the PCB routing away from the edge to connect between adjacent copper layers. The particular thickness of the copper traces, number of stands, number of layers, and width of the traces of the Litz conductor 1355 can be selected to modify and achieve the desired performance and characteristics of the Litz PCB winding 1400 incorporating the 3D Litz PCB winding 1302. For example, the number of strands and the width of each strand (trace) can affect the proximity effect and window space utilization, lowering resistivity and lowering AC losses. In general, the more strands and the smaller the width of each strand (trace), the less the proximity effect, the lower the window space utilization, the lower the resistance, and the lower the AC losses.

[0071] Still referring to FIG. 14, the 3D Litz PCB routing (Litz conductor 1355) includes solid windings 1440 around four corner edges 1445. The solid corners allow the strands (or traces) between the two solid corner edges to have the same length of Litz wire. When the traces reach the edge of the PCB printed inductor, vias and / or electrical connections between the copper layers help the traces to switch layers and proceed in another symmetric diagonal direction. The copper layers can be designed according to the skin depth so that the round Litz wire conductors are not affected by the skin effect from both the top and bottom sides of the Litz PCB winding. For example, the thickness of the copper traces may be less than twice the skin depth.

[0072] 14, each layer of the 3D Litz PCB routing includes solid terminal pads 1455 and castellated holes 1460. The solid terminal pads 1455 and castellated holes 1460 of different layers are aligned and connect different layers of the PCB windings of the circuit board. Two solid terminal pads 1455 extend laterally from the 3D Litz routing between two corner edges 1445. The two solid terminal pads 1455 are separated by a gap 1465. The distal ends 1470 of the two solid terminal pads 1455 include castellated holes 1460 that extend outwardly away from the two solid terminal pads 1455 in opposite directions. The castellated holes 1460 provide alignment between layers of the winding board while establishing electrical connections. The solid terminal pads 1455 and castellated holes 1460 allow the winding lengths of the 3D ex-Litz routing to be balanced turn by turn.

[0073] The multiple layers of Litz conductors 1355 shown in FIG. 14 provide one conductive loop or winding for the inductor, starting at a first node (first stack of castellated holes 1460 and terminal pads 1455) and ending at a second node (the other stack of castellated holes 1460 and terminal pads 1455). If the inductor includes multiple Litz PCB windings 1302, each including a Litz conductor 1355 as shown in FIG. 14, a multi-loop winding can be formed (across the stacked Litz PCB windings 1302) by connecting the nodes of each Litz conductor 1355 to the nodes of another Litz conductor 1355 to connect the conductive loops formed by the respective Litz conductors 1355 in series. A pair of terminals on the solid wiring PCB winding 1300 of FIG. 13A can be similarly used to connect the conductive loops provided by the embedded windings of the PCB 1300 in series, thereby forming a multi-loop winding (across the stacked solid PCB windings 1300). In some examples, multiple series-connected Litz conductors 1355 are included in a single circuit board to provide a Litz PCB winding with a multi-loop winding of Litz conductors. In some examples, each double layer of the Litz conductors 1355 forms a "loop" and the two loops (each set of double layers) are connected in series. Thus, a Litz PCB winding with a Litz conductor 1355 having four layers may be a two-loop winding in this configuration. In other embodiments, the Litz conductors 1355 have more or fewer layers connected in series to provide a Litz PCB winding with more or fewer loops.

[0074] Referring now to FIG. 15, a 3D litz routing 1500 is shown that includes 40 strands of litz wire and 4 layers of litz routing. The 3D litz routing 1500 is an expanded view of a portion of the litz conductor 1355 of FIG. 13B and FIG. 14. Three representative strands of the top layer of the routing 1500 are identified as strands 1501, 1502, and 1503. In FIG. 15, the strands of the top layer and the third layer, including strands 1501, 1502, and 1503, generally extend diagonally upward and to the left (when starting from the lower portion 1504 of the routing 1500). In contrast, the strands of the lower layer and the second layer generally extend upward and to the right (when starting from the lower portion 1504 of the routing).

[0075] 16, the routing 1500 is shown separated into its four layers. The top layer 1505 includes a left-right mode 1510 and a via-up mode 1515 between the winding edges 1520. The second layer 1525 includes a left-right mode 1530 and a via-down mode 1535 between the winding edges 1520. The third layer 1540 includes a left-right mode 1510 and a via-up mode 1515 between the winding edges 1520. The bottom layer 1545 includes a left-right mode 1530 and a via-down mode 1535 between the winding edges 1520. Solid terminal pads 1455 and castellated holes 1460 align the four layers of the litz routing 1500. As shown in FIG. 13B, the four layers of the litz routing 1500 form the litz conductors 1355 of the litz PCB winding 1302. Although the example of FIG. 16 includes four layers, in some examples more or fewer layers of Litz conductors 1355 are used to form the Litz PCB winding.

[0076] FIG. 17 shows resistivity measurements of different layers of a Litz PCB winding 1302 and a solid PCB winding 1300 at different frequencies. Proximity effects affect copper losses, and resistivity can increase with the number of stacks. From the results shown, a Litz PCB winding or Litz routing structure has a smaller resistivity that is more suitable for high frequency applications, especially when multiple layers of PCB windings are stacked to form an inductor. For example, single and two layer Litz routing PCBs have lower resistivity than a single layer of regular Litz wire and solid PCB winding at low to high frequencies, and three and four layer Litz routing PCBs have significantly lower resistivity than solid PCB windings of equivalent layers.

[0077] 18 and 19 show plots of data points based on experimental testing of different inductor designs with respect to inductor (power) loss, cost, and volume, where the inductors were used in power converters with critical soft switching conditions of high frequency (100 kHz to 1 MHz) and high current ripple (50 A). These conditions could not be adequately handled by the benchmarked commercial inductors due to high losses and temperature rise. Referring to the "EE" shape core 700 with Litz wire inductor 715 in FIG. 7A, the wired inductor has relatively low losses, higher cost, and higher volume. The "EE" shape core 700 with Litz PCB windings 760 shown in FIG. 7B has relatively small volume, higher losses, and lower cost. The "II" shape core 1000 and the "EA" shape core 900 have relatively small volume, low cost, and higher losses.

[0078] Figure 18 shows inductor loss versus inductor volume. Commercially available inductors are shown for comparison with different core shapes, number of turns, and winding types. The Litz PCB winding 1302 and solid PCB winding 1300 on the "II" core 1000 and "EA" core 900 show lower volume per inductor loss.

[0079] FIG. 19 shows inductor loss compared to the manufacturing cost of the inductor. Commercially available inductors are shown compared with different core shapes, number of turns, and winding types. The Litz PCB winding 1302 and solid PCB winding 1300 on the "II" core 1000 and "EA" core 900 show a lower cost per inductor loss.

[0080] V. Composite PCB with converter circuit and LC filter inductor In some embodiments, one or more components of the power converter circuit are disposed (e.g., embedded, mounted, etc.) on a printed circuit board (PCB). These one or more components may include, for example, the electronic controller 105 or portions thereof (e.g., the processor 145, the memory 150, one or more gate drivers, etc.), the power converter 115 (e.g., one or more of the power switching elements that make up the power converter 115), or a combination thereof. In some examples, in combination with these one or more components of the power converter circuit, the inductor of the LC filter 120 is disposed on the same PCB, resulting in a composite PCB. For example, the PCB may include at least one turn of the coil portion of the inductor (whether as a solid wire, as a Litz conductor, or in another form) and may be sandwiched between two "I" cores (i.e., as part of an inductor having an "II" shaped core portion, as described in FIGS. 10A and 10B) or integrated with another core portion shape (e.g., see FIGS. 7A-10B and the EE, EI, and EA cores above).

[0081] 20, a single PCB 1900 may include an inductor 1905 combined with one or more components. For example, one or more individual PCBs including the inductor 1905, the controller 1910, and / or the gate driver 1915 / SiC MOSFET 1920 may be replaced with a single PCB 1900 on which the inductor 1905 and one or more of the controller 1910, the gate driver 1915, the SiC MOSFET 1920, the input capacitor 1925, the DC input 1930, the voltage sensor 1935, the current sensor 1940, the DC output 1945, or the output capacitor 1950 are disposed. The inductor 1905 includes one of the aforementioned embedded windings, such as the solid winding 1315 (in FIG. 13A) or the Litz conductor 1355 (in FIG. 13B), as a winding portion embedded in the PCB 1900. Thus, the PCB 1900 can be considered, at least in part, as a solid or Litz PCB winding of the inductor 1905. The inductor 1905 further includes a core having, for example, an "II" shape, an "EA" shape, an "EI" shape, or an "EE" shape as a core portion. Thus, the PCB 1900 can include an opening (e.g., opening 1325 or 1365 as shown in Figures 13A-13B) that accepts and receives the legs of the core (e.g., in the case of an "E" shaped base). The combined single PCB 1900 can provide a more compact power converter with increased power density and reduced material that would otherwise be present for a multi-PCB implementation. In some examples, the coil portion of the inductor includes one or more additional PCBs stacked with the composite PCB to provide additional turns. These additional PCBs may be located on one side of the composite PCB (e.g., stacked above or below the composite PCB) or on both sides of the composite PCB. In either case, the turn(s) of each PCB is conductively coupled to the turn(s) of the other PCBs in the stack, and the turns of the PCBs are aligned or approximately concentric. See, for example, the stacks of PCBs (and corresponding turns of the inductors) shown in Figures 7B, 8B, 9B, and 10B.

[0082] As provided herein, inductors for LC filters in power converters can have a variety of characteristics and properties associated with both the winding and core portions, including size, shape, number of turns, winding type, etc. A particular combination of these properties can be selected to meet a particular design requirement or preference. Some considerations for such designs are provided here. In general, inductance decreases linearly with current level, and magnetic energy increases with the square of the current. The inductance of the inductor of the LC filter 120 can be designed around the area product of the energy -1 / 2(Li^2)^(3 / 4).

[0083] The scaling relationship can be given by the following equation, which describes the inductor (and magnetic) laws:

number

number

[0084] Thus, changing the number of turns, for example to increase the number of turns in parallel or series, results in different levels of current or inductance. As used herein with respect to inductors, a "turn" may also be referred to as a conductor loop.

[0085] FIG. 21 illustrates a process 2100 for power conversion. Process 2100 is described as being performed by power converter system 100 implementing power converter 200 as power converter 115 and including one of the disclosed inductors provided herein as the switch-side inductor of filters 120, 245, 308 (or the inductor for each phase as shown in FIG. 3). However, in some embodiments, process 2100 may be performed by another power converter system or by power converter system 100 using another power converter as power converter 115. Additionally, although the blocks of process 2100 are shown in a particular order, in some embodiments one or more of the blocks may be performed partially or wholly in parallel, may be performed in a different order than that shown in FIG. 21, or may be bypassed.

[0086] In block 2105, a power converter including a power switching element (e.g., power converter system 100) receives input power. For example, referring to FIG. 2, a DC voltage terminal (e.g., DC voltage terminal 220) receives an input DC voltage, including a positive DC terminal 222 and a negative DC terminal 224 located on the DC side of the power converter. The input DC voltage may be provided by a DC power source, such as a battery, a capacitor, an ultracapacitor, a DC power source from a rectified AC power source (e.g., AC grid power converted to DC power by a diode bridge rectifier). Alternatively, an interface terminal (e.g., interface terminal 225) receives an AC input voltage. The AC input voltage may be provided by an AC power source, such as a power grid, an AC generator (e.g., an engine-driven generator), or the like.

[0087] In block 2110, a controller (e.g., controller 105) drives a pair of power switching elements to convert the received input power. If the received input power is DC power, the power switching elements convert the DC power to AC power and output it via interface terminal 225. If the received input power is AC power, the power switching elements convert the AC power to DC power and output it via DC terminal 220. In some examples, the controller 105 drives the power switching elements with variable frequency critical soft switching (VFCSS) as described above. The controller 105 outputs PWM control signals to gate terminals of the power switching elements to drive the power switching elements. To generate the PWM control signals for driving the power switching elements (e.g., switches 235, 240), the controller 105 can sense or estimate the operating characteristics of the power converter and increase or decrease the duty cycle (frequency, in the case of VFCSS) of the PWM control signals accordingly. For example, the controller 105 may implement a proportional-integral-derivative (PID) controller that receives the converter's input voltage command (reference voltage) and the measured voltage at the converter's output (e.g., at interface terminal 225). The PID controller may then generate a reference current signal based on the difference between the reference voltage and the measured voltage using standard PID techniques. In general, if the measured voltage is below the reference voltage, the reference current signal increases, and vice versa. The reference current may then be converted into a reference duty cycle value (e.g., a value between 0 and 100%) that indicates the percentage of each switching cycle that the upper switch (M1) 135 should be on and off, and similarly, the percentage of each switching cycle that the lower switch (M2) 140 should be off. In general, the duty cycle of the upper switch (M1) 135 increases as the reference current increases, within certain operating boundaries. The controller 105 (or its gate driver) may then generate the respective PWM control signal according to the reference duty cycle. This PID controller is just one example of a control scheme for generating control signals for driving power switching elements.In another example, in block 2110, the controller 105 implements another control scheme, such as cascade PID control, state-based control, model predictive control (MPC), or another coordinated control scheme for driving the power switching elements of the modified converter 210. For example, the controller 105 can implement the VFCSS using another control scheme.

[0088] In block 2115, an LC filter including an inductor and a capacitor coupled to the first side of the power converter (e.g., LC filter 120, 245, 308) filters the power signal on the first side of the power converter. The power signal received by the LC filter can have a current ripple of at least 200% peak-to-peak ripple relative to the local average current.

[0089] The switch-side inductor of the LC filter (e.g., switch-side inductor 250 of LC filter 120, 245, 308) may be implemented as one of the inductors provided herein, such as one of the inductors including a PCB winding, whether a solid PCB winding (see, e.g., FIG. 13A) or a Litz PCB winding (see, e.g., FIG. 13B). The filtered output voltage may be either an AC voltage provided to interface terminal 225 or a DC voltage provided to DC terminal 220, depending on the control or drive of the power switching elements.

[0090] As previously mentioned, in some examples, the LC filter 120, 245 includes an additional inductor coupled between the filter node 260 and the positive interface terminal 227, thereby providing an LCL filter. Additionally, in some examples, the LC filter further includes an upper capacitor (see upper capacitor 215 in FIG. 2) that can reduce ripple current by providing a path for the ripple current to propagate between the DC terminal and the interface terminal and cancel at least a portion of the differential mode current ripple between the DC terminal and the interface terminal. In some examples, each power switching element (e.g., upper and lower switches 235, 240) includes a drain-to-source capacitor (C DS In some examples, the LC filter of process 2100 is included in a composite PCB, such as provided with respect to FIG.

[0091] Execution of the various techniques and operations described herein may be facilitated by a controller device (e.g., a processor-based computing device). Such a controller device may include a processor-based device, such as a computing device, which may include a central processing unit (CPU) or processing core. In addition to the CPU or processing core, the system includes a main memory, a cache memory, and a bus interface circuit. The controller device may include a memory storage device, such as a hard drive (solid state hard drive or other type of hard drive) or a flash drive, associated with the computer system. The controller device may further include a keyboard, keypad, or some other user input interface, and a monitor, such as an LCD (liquid crystal display) monitor, and may be located where a user can access them.

[0092] The controller device is configured to facilitate, for example, the implementation of a voltage converter (e.g., by controlling switching devices of, for example, a non-isolated three-phase DC / AC voltage converter system). Thus, the storage device may include a computer program product that, when executed on the controller device (which may be a processor-based device, as previously described), causes the processor-based device to perform operations that facilitate implementation of the procedures and operations described herein. The controller device may further include peripheral devices for enabling input / output functions. Such peripherals may include, for example, a 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 relevant content to a connected system. Such peripherals may also be used to download software including computer instructions for enabling general operation of the respective system / device. Alternatively and / or additionally, in some embodiments, dedicated logic circuits, such as, for example, an FPGA (field programmable gate array), an ASIC (application specific integrated circuit), a DSP processor, a graphics processing unit (GPU), an application processing unit (APU), etc., may be used in the implementation of the controller device. Other modules that may be included in the controller device may include a user interface for providing or receiving input and output data. The controller device may include an operating system.

[0093] A computer program (also referred to as a program, software, software application or code) includes machine instructions for a programmable processor and may be implemented in a high-level procedural and / or object-oriented programming language and / or in an assembly / machine language. As used herein, the term "machine-readable medium" refers to any non-transitory computer program product, apparatus and / or device used to provide machine instructions and / or data to a programmable processor (e.g., magnetic disks, optical disks, memory, programmable logic devices (PLDs)), including non-transitory machine-readable media that receive machine instructions as machine-readable signals.

[0094] In some embodiments, any suitable computer-readable medium can be used to store instructions for performing the processes / operations / procedures described herein. For example, in some embodiments, a computer-readable medium can be transitory or non-transient. For example, a non-transient computer-readable medium can include media such as magnetic media (e.g., hard disks, floppy disks, etc.), optical media (e.g., compact disks, digital video disks, Blu-ray disks, etc.), semiconductor media (e.g., flash memory, electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), any suitable media that is not transitory or lacks any representation of permanence in transmission, and / or any suitable tangible media. As another example, a transitory computer-readable medium can include signals, wires, conductors, optical fibers, circuits on a network, or any suitable media that is transitory and does not lack any representation of permanence in transmission, and / or any suitable intangible media.

[0095] Although certain embodiments have been disclosed in detail herein, this is done by way of example for illustrative purposes only and is not intended to be limiting with respect to the scope of the following appended claims. Features of the disclosed embodiments can be combined, rearranged, etc., within the scope of the invention to produce many more embodiments. Certain other aspects, advantages, and modifications are believed to be within the scope of the claims provided below. The presented claims represent at least some of the embodiments and features disclosed herein. Other unclaimed embodiments and features are also contemplated.

[0096] Further examples Example 1: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for a non-isolated power converter system comprising: a power converter including a power switching element; a controller configured to drive the power switching element to convert received power and to output converted power, the controller configured to drive the power switching element using variable frequency soft switching; and a filter including an inductor and a capacitor coupled to a first side of the power converter to filter a power signal of the first side of the power converter, wherein the power signal received by the filter has a current ripple of at least 200% peak-to-peak ripple relative to a local average current, the inductor including a core portion and a winding portion, the winding portion including a winding embedded in a printed circuit board.

[0097] Example 2: The method, apparatus, and / or non-transitory computer-readable medium of Example 1, wherein each loop of the winding is a wire conductor having a solid cross-section.

[0098] Example 3: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 or 2, wherein the windings are embedded in a printed circuit board to form a Litz PCB including multiple layers of parallel strands in which the windings are routed within the printed circuit board.

[0099] Example 4: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 3, wherein the Litz PCB includes at least one or more layers of parallel strands, each of the parallel strands being a conductive trace.

[0100] Example 5: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 4, wherein the winding portion includes one or more additional Litz PCBs, each additional Litz PCB including an additional winding including multiple layers of parallel strands routed within an additional printed circuit board.

[0101] Example 6: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 5, wherein the core portion includes a first core portion opposite the second core portion of the winding portion, and the first core portion and the second core portion include a plane facing the conductor loop and substantially parallel to the printed circuit board.

[0102] Example 7: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 6, wherein the core portion includes a first core portion facing the outside air portion, the first core portion having a base portion and three legs extending therefrom, and a middle leg of the three legs extending through an opening defined by the conductor loop.

[0103] Example 8: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 7, wherein the printed circuit board further includes one or more of a controller or one or more of power switching elements located thereon.

[0104] Example 9: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 1 to 8, wherein the first side of the power converter is selected from the group of a DC output side for DC / DC conversion, an AC output side for DC / AC inversion, and an AC input side for AC / DC rectification.

[0105] Example 10: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for a power conversion method comprising: receiving input power by a power converter including a power switching element; driving the power switching element by a controller to convert the received input power and output a converted power, wherein the controller is configured to drive the power switching element using variable frequency soft switching; and filtering a power signal on a first side of the power converter with an LC filter including an inductor and a capacitor coupled to the first side of the power converter, wherein the power signal received by the filter has a current ripple of at least 200% peak-to-peak ripple relative to a local average current, wherein the inductor includes a core portion and a winding portion, the winding portion including windings embedded in a printed circuit board.

[0106] Example 11: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for an inductor for a filter in a non-isolated power converter system, the inductor comprising: a core portion; and a winding portion forming an inductor with the core portion, the winding portion being embedded in a printed circuit board and including a winding having a first terminal and a second terminal, the winding embedded in the printed circuit board forming a Litz PCB, the winding including multiple layers of parallel strands that are routed within the printed circuit board.

[0107] Example 12: The method, apparatus, and / or non-transitory computer-readable medium of Example 11, wherein the Litz PCB includes at least two layers of parallel strands, each of the parallel strands being a conductive trace.

[0108] Example 13: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 11 or 12, wherein the winding portion includes one or more additional Litz PCBs, each additional Litz PCB including an additional winding including multiple layers of parallel strands routed within an additional printed circuit board.

[0109] Example 14: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 11 to 13, wherein the core portion includes a first core portion opposite the second core portion of the winding portion, and the first core portion and the second core portion include a plane facing the conductor loop and substantially parallel to the printed circuit board.

[0110] Example 15: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 11 to 14, wherein the core portion includes a first core portion facing the outside air portion, the first core portion having a base portion and three legs extending therefrom, and a middle leg of the three legs extending through an opening defined by the conductor loop.

[0111] Example 16: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 11 to 15, wherein the inductor is part of an LC filter that filters a power signal of the power converter, and the printed circuit board further includes one or more of: one or more power switching elements of the power converter located thereon; or a controller configured to drive the one or more power switching elements of the power converter.

[0112] Example 17: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 11 to 16, wherein the power converter is selected from the group of a DC / DC converter, a DC / AC inverter, and an AC / DC rectifier.

[0113] Example 18: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for an inductor for a filter in a non-isolated power converter system, the inductor comprising: a winding portion including a winding embedded in a printed circuit board, the winding forming a conductor loop and including a first terminal and a second terminal; and a core portion forming the inductor together with the winding portion, the core portion including the first core portion on an opposite side of the winding portion from the second core portion, the first core portion and the second core portion having a plane facing the conductor loop that is substantially parallel to the printed circuit board.

[0114] Example 19: The method, apparatus, and / or non-transitory computer-readable medium of Example 18, wherein the core portion includes a first core portion opposite the second core portion of the winding portion, and a plurality of printed circuit boards are sandwiched between the first core portion and the second core portion.

[0115] Example 20: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18 or 19, wherein the conductor loops of the winding are wiring conductors having a solid cross-section.

[0116] Example 21: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18-20, wherein the windings embedded in the printed circuit board form a Litz PCB including multiple layers of parallel strands in which the windings are routed within the printed circuit board.

[0117] Example 22: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18-21, wherein the Litz PCB includes at least four layers of parallel strands, each of the parallel strands being a conductive trace.

[0118] Example 23: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18 to 22, wherein the winding portion includes one or more additional Litz PCBs, each additional Litz PCB including an additional winding including multiple layers of parallel strands routed within an additional printed circuit board.

[0119] Example 24: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18 to 23, wherein the inductor is part of an LC filter that filters a power signal of the power converter, and the printed circuit board further includes one or more of the following: one or more power switching elements of the power converter located thereon, or a controller configured to drive the one or more power switching elements of the power converter.

[0120] Example 25: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 18 to 24, wherein the power converter is selected from the group of a DC / DC converter, a DC / AC inverter, and an AC / DC rectifier.

[0121] Example 26: A method, apparatus, and / or non-transitory computer-readable medium storing processor-executable instructions for an inductor for a filter in a non-isolated power converter system, the inductor comprising: a winding portion including a winding embedded in a printed circuit board, the winding forming a conductor loop and including a first terminal and a second terminal; and a core portion forming an inductor together with the winding portion, the core portion including a first core portion facing the outside air portion, the first core portion having a base portion and three legs extending therefrom, the middle leg of the three legs extending through an opening defined by the conductor loop.

[0122] Example 27: The method, apparatus, and / or non-transitory computer-readable medium of Example 26, wherein an outermost leg of the first core portion is parallel to a middle leg of the three legs, and the outermost leg has a different thickness than the middle leg.

[0123] Example 28: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 27.

[0124] Example 29: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 28, wherein the conductor loops of the winding are wiring conductors having a solid cross-section.

[0125] Example 30: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26-29, wherein the windings are embedded in the printed circuit board to form a Litz PCB including multiple layers of parallel strands in which the windings are routed within the printed circuit board.

[0126] Example 31: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 30, wherein the Litz PCB includes at least four layers of parallel strands, each of the parallel strands being a conductive trace.

[0127] Example 32: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 31, wherein the winding portion includes one or more additional Litz PCBs, each additional Litz PCB including an additional winding including multiple layers of parallel strands routed within an additional printed circuit board.

[0128] Example 33: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 32, wherein the inductor is part of an LC filter that filters a power signal of the power converter, and the printed circuit board further includes one or more of the following: one or more power switching elements of the power converter located thereon; or a controller configured to drive the one or more power switching elements of the power converter.

[0129] Example 34: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 26 to 33, wherein the power converter is selected from the group of a DC / DC converter, a DC / AC inverter, and an AC / DC rectifier.

[0130] Example 35: A power converter including a power switching element; a controller configured to drive the power switching element to convert received power and output converted power; a filter including an inductor and a capacitor, coupled to a first side of the power converter to filter a power signal at the first side of the power converter, the inductor including a core portion and a winding portion, a winding of the winding portion being embedded in the filter; and the controller; or and a printed circuit board on which one or more of the power switching elements are located.

[0131] Example 36: The method, apparatus, and / or non-transitory computer-readable medium of Example 35, wherein each loop of the winding is a wiring conductor having a solid cross-section.

[0132] Example 37: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 or 36, wherein the windings embedded in the printed circuit board form a Litz PCB including multiple layers of parallel strands in which the windings are routed within the printed circuit board.

[0133] Example 38: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 37, wherein the Litz PCB includes at least four layers of parallel strands, each of the parallel strands being a conductive trace.

[0134] Example 39: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 38, wherein the winding portion includes one or more additional Litz PCBs, each additional Litz PCB including an additional winding including multiple layers of parallel strands routed within an additional printed circuit board.

[0135] Example 40: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 39, wherein the core portion includes a first core portion opposite the second core portion of the winding portion, and the first core portion and the second core portion include a plane facing the conductor loop and substantially parallel to the printed circuit board.

[0136] Example 41: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 40, wherein the core portion includes a first core portion facing the outside air portion, the first core portion having a base portion and three legs extending therefrom, and a middle leg of the three legs extending through an opening defined by the conductor loop.

[0137] Example 42: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 41, wherein the printed circuit board further includes one or more of a controller or one or more of power switching elements located thereon.

[0138] Example 43: The method, apparatus, and / or non-transitory computer-readable medium of any of Examples 35 to 42, wherein the power converter is selected from the group of a DC / DC converter, a DC / AC inverter, and an AC / DC rectifier.

[0139] Example 44: A non-transitory computer-readable medium storing methods, apparatus, and / or processor-executable instructions for a power conversion method including the steps of receiving input power by a power converter including a power switching element; driving the power switching element by a controller to convert the received input power and output a converted power, where one or more of (i) the controller or (ii) one or more of the power switching elements are located on a printed circuit board; and filtering a power signal at a first side of the power converter by an LC filter including an inductor and a capacitor coupled to the first side of the power converter, where the inductor includes a core portion and a winding portion, and the winding portion includes a winding embedded in the printed circuit board.

[0140] Example 45: The method, apparatus, and / or non-transitory computer-readable medium of Example 44, wherein the step of driving the power switching element by the controller to convert the received input power and output the converted power includes at least one selected from the group of steps of: converting the input power from a first DC voltage level to a second DC voltage level in the output converted power, where the first side of the power converter is the DC output side; converting the input power from DC to AC in the output converted power, where the first side of the power converter is the AC output side; or converting the input power from AC to DC in the output converted power, where the first side of the power converter is the AC input side.

Claims

1. A power converter including a power switching element, A controller configured to drive the power switching element to convert received power and output the converted power, the controller being configured to drive the power switching element using variable frequency soft switching, A filter including an inductor and a capacitor, coupled to a first side of the power converter to filter a power signal on the first side of the power converter, the power signal received by the filter having a current ripple of at least 200% peak-to-peak ripple with respect to a local average current, Comprising, The inductor includes a core portion and a winding portion, and the winding portion includes a winding embedded in a printed circuit board, A non-insulated power converter system.

2. The non-insulated power converter system according to claim 1, wherein each loop of the winding is a solid cross-section wiring conductor.

3. The non-insulated power converter system according to claim 1, wherein the winding embedded in the printed circuit board forms a Litz PCB including a plurality of layers of parallel strands routed within the printed circuit board.

4. The non-insulated power converter system according to claim 3, wherein the Litz PCB includes at least two layers of parallel strands, and each strand of the parallel strands is a conductive trace.

5. The non-insulated power converter system according to claim 3, wherein the winding portion includes one or more additional Litz PCBs, and each of the additional Litz PCBs includes an additional winding including a plurality of layers of parallel strands routed within an additional printed circuit board.

6. The non-insulated power converter system according to claim 1, wherein the core portion includes a first core portion opposite a second core portion of the winding portion, and the first core portion and the second core portion include a plane substantially parallel to the printed circuit board facing the conductor loop.

7. The non-insulated power converter system according to claim 1, wherein the core portion includes a first core portion facing an outer air portion, the first core portion having a base portion and three legs extending therefrom, and an intermediate leg of the three legs extending through an opening defined by the conductor loop.

8. The printed circuit board further includes one or more of the following components located thereon: the controller, or one or more of the power switching elements, The non-insulated power converter system according to claim 1. **Claim 9** The first side of the power converter is selected from the group consisting of a DC output side for DC / DC conversion, an AC output side for DC / AC inversion, and an AC input side for AC / DC rectification. The non-insulated power converter system according to claim 1. **Claim 10** Receiving input power by a power converter including a power switching element; Driving the power switching element by a controller to convert the received input power and output the converted power, wherein the controller is configured to drive the power switching element using variable frequency soft switching; Filtering a power signal on the first side of the power converter by an LC filter including an inductor and a capacitor coupled to the first side of the power converter, wherein the power signal received by the filter has a current ripple of at least 200% peak-to-peak ripple with respect to the local average current; comprising The inductor includes a core portion and a winding portion, and the winding portion includes a winding embedded in a printed circuit board. A power conversion method. **Claim 11** Each loop of the winding is a solid cross-section wiring conductor. The method according to claim 10. **Claim 12** The winding embedded in the printed circuit board forms a Litz PCB including a plurality of layers of parallel strands in which the winding is routed within the printed circuit board. The method according to claim 10. **Claim 13** The Litz PCB includes at least two layers of parallel strands, and each strand of the parallel strands is a conductive trace. The method according to claim 12. **Claim 14** The winding portion includes one or more additional Litz PCBs, and each of the additional Litz PCBs includes an additional winding including a plurality of layers of parallel strands routed within an additional printed circuit board. The method according to claim 12. **Claim 15** The core portion includes a first core portion on the side opposite to the second core portion of the winding portion, and the first core portion and the second core portion include a plane substantially parallel to the printed circuit board facing the conductor loop. The method according to claim 10.

16. The core portion includes a first core portion facing the outside air portion, and the first core portion has a base portion and three leg portions extending therefrom. The middle leg portion of the three leg portions extends through an opening defined by a conductor loop. The method according to claim 10.

17. The printed circuit board has located thereon the controller, or one or more of the power switching elements, and further includes one or more of them. The method according to claim 10.

18. The step of driving the power switching element by the controller to convert the received input power and output the converted power is a step of converting the input power from a first DC voltage level to a second DC voltage level in the converted power output, wherein the first side of the power converter is a DC output side. a step of converting the input power from DC to AC in the converted power output, wherein the first side of the power converter is an AC output side, or a step of converting the input power from AC to DC in the converted power output, wherein the first side of the power converter is an AC input side. The method according to claim 10 includes at least one selected from the group of

19. A power converter including a power switching element, a controller configured to drive the power switching element to convert the received power and output the converted power, a filter including an inductor and a capacitor, coupled to a first side of the power converter to filter a power signal at the first side of the power converter, and the inductor includes a core portion and a winding portion. The winding of the winding portion is embedded, and the controller, or one or more of the power switching elements, and one or more of them are located thereon. A printed circuit board, comprising The winding embedded in the printed circuit board forms a Litz PCB including a plurality of layers of parallel strands in which the winding is routed within the printed circuit board, for a non-insulated power converter system.

20. The non-insulated power converter system according to claim 19, wherein the Litz PCB includes at least two layers of parallel strands, and each strand of the parallel strands is a conductive trace.

21. The non-insulated power converter system according to claim 19, wherein the winding portion includes one or more additional Litz PCBs, and each of the additional Litz PCBs includes an additional winding including a plurality of layers of parallel strands routed within an additional printed circuit board.

22. The non-insulated power converter system according to claim 19, wherein the core portion includes a first core portion on a side opposite to a second core portion of the winding portion, and the first core portion and the second core portion include a plane substantially parallel to the printed circuit board facing a conductor loop formed by the winding.

23. The non-insulated power converter system according to claim 19, wherein the core portion includes a first core portion facing an outside air portion, the first core portion has a base portion and three legs extending therefrom, and an intermediate leg of the three legs extends through an opening defined by a conductor loop formed by the winding.

24. A method comprising receiving input power by a power converter including a power switching element; driving, by a controller, the power switching element to convert the received input power and output the converted power, wherein one or more of (i) the controller or (ii) the power switching element are located on a printed circuit board; filtering, by an LC filter including an inductor and a capacitor coupled to a first side of the power converter, a power signal at the first side of the power converter, wherein the inductor includes a core portion and a winding portion, and the winding portion includes a winding embedded in the printed circuit board; comprising The winding embedded in the printed circuit board forms a Litz PCB including a plurality of layers of parallel strands in which the winding is routed within the printed circuit board. Claim 25 The method according to claim 24, wherein the litz PCB includes at least two layers of parallel strands, and each strand of the parallel strands is a conductive trace. Claim 26 The method according to claim 24, wherein the winding portion includes one or more additional litz PCBs, and each of the additional litz PCBs includes an additional winding including a plurality of layers of parallel strands routed within an additional printed circuit board. Claim 27 The core portion includes a first core portion on the side opposite to the second core portion of the winding portion, wherein the first core portion and the second core portion include a plane substantially parallel to the printed circuit board facing a conductor loop formed by the winding. The method according to claim 24. Claim 28 The core portion includes a first core portion facing an outside air portion, the first core portion having a base portion and three legs extending therefrom, and an intermediate leg of the three legs extending through an opening defined by a conductor loop formed by the winding. The method according to claim 24.

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