System and method for active discharge for inverter for electric vehicle

Abstract

A system includes: an inverter configured to convert DC power from a battery to AC power to drive a motor, where the inverter includes: a bulk capacitor; one or more phase switching members; and one or more controllers configured to control a gate voltage to the one or more phase switches to discharge the bulk capacitor, wherein the one or more controllers are configured to control the gate voltage based on one or more of the measured temperature of the one or more phase switches or the estimated temperature of the one or more phase switches.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. non-provisional patent application No. 18 / 310,049 filed on May 1, 2023, which claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 377,486 filed on September 28, 2022, U.S. Provisional Patent Application No. 63 / 377,501 filed on September 28, 2022, U.S. Provisional Patent Application No. 63 / 377,512 filed on September 28, 2022, and U.S. Provisional Patent Application No. 63 / 378,601 filed on October 6, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Various embodiments of the present disclosure relate generally to systems and methods for controlling active discharge of an inverter for an electric vehicle, and more particularly to systems and methods for controlling active discharge based on temperature of an inverter for an electric vehicle. Background Art

[0004] Inverters, such as those used to drive motors in electric vehicles, are responsible for converting high voltage direct current (HVDC) to alternating current (AC) to drive the motor. In the inverter, bulk capacitors are discharged in the event of a fault condition to reduce the risk of contact with high voltages. Active discharge of bulk capacitors can stress the power switching components.

[0005] The present disclosure is directed to overcoming one or more of these aforementioned challenges. Summary of the invention

[0006] In some aspects, the technology described herein relates to a system comprising: an inverter configured to convert DC power from a battery into AC power to drive a motor, wherein the inverter comprises: a large-capacity capacitor; one or more phase switching elements; and one or more controllers configured to control a gate voltage to the one or more phase switching elements to discharge the large-capacity capacitor, wherein the one or more controllers are configured to control the gate voltage based on one or more of a measured temperature of the one or more phase switching elements or an estimated temperature of the one or more phase switching elements.

[0007] In some aspects, the technology described herein relates to a system in which the one or more controllers are point-of-use controllers.

[0008] In some aspects, the technology described herein relates to a system wherein the one or more controllers are gate drivers for the one or more phase switches.

[0009] In some aspects, the technology described herein relates to a system wherein the one or more phase switches include one or more silicon carbide grains.

[0010] In some aspects, the technology described herein relates to a system wherein the one or more controllers include one or more thermal sensors for measuring a temperature of the one or more phase switching elements.

[0011] In some aspects, the technology described herein relates to a system wherein the inverter further comprises: one or more thermistors for measuring a temperature of the one or more phase switching components.

[0012] In some aspects, the technology described herein relates to a system wherein the one or more controllers are further configured to control the gate voltage based on a measured temperature of the one or more phase switching elements measured prior to active discharge of the inverter.

[0013] In some aspects, the technology described herein relates to a system that further includes a battery configured to supply DC power to an inverter and a motor configured to receive AC power from the inverter to drive the motor.

[0014] In some aspects, the technology described herein relates to a system comprising: a power module for an inverter configured to convert DC power to AC power, the power module including a drain terminal and a source terminal; one or more phase switches configured to control current between the drain terminal and the source terminal; and a point-of-use controller configured to control a gate voltage to the one or more phase switches to discharge a bulk capacitor of the inverter, wherein the point-of-use controller is configured to control the gate voltage based on one or more of a measured temperature of the one or more phase switches or an estimated temperature of the one or more phase switches.

[0015] In some aspects, the techniques described herein relate to a system in which the point-of-use controller is an application specific integrated circuit gate driver for the one or more phase switches.

[0016] In some aspects, the technology described herein relates to a system wherein the one or more phase switches include one or more silicon carbide grains.

[0017] In some aspects, the technology described herein relates to a system wherein a point-of-use controller includes one or more thermal sensors for measuring a temperature of the one or more phase switching components.

[0018] In some aspects, the technology described herein relates to a system wherein the point of use controller is further configured to control the gate voltage based on a measured temperature of the one or more phase switching elements measured prior to active discharge of the inverter.

[0019] In some aspects, the technology described herein relates to a system wherein the point of use controller is further configured to control the gate voltage by reducing the gate voltage while maintaining a drain current of the one or more phase switching elements above a threshold level.

[0020] In some aspects, the technology described herein relates to a system comprising one or more controllers configured to: determine one or more of a measured temperature of a phase switching element or an estimated temperature of the phase switching element; and control a gate voltage to the phase switching element to discharge a bulk capacitor of an inverter, wherein the one or more controllers are configured to control the gate voltage based on one or more of the measured temperature of the phase switching element or the estimated temperature of the phase switching element.

[0021] In some aspects, the technology described herein relates to a system in which the one or more controllers are point-of-use controllers.

[0022] In some aspects, the technology described herein relates to a system wherein the one or more controllers are further configured to determine a measured temperature of a phase switch using a thermal sensor of the one or more controllers.

[0023] In some aspects, the technology described herein relates to a system wherein the one or more controllers are further configured to control the gate voltage based on a measured temperature of the phase switching element measured prior to active discharge of the inverter.

[0024] In some aspects, the technology described herein relates to a system wherein the one or more controllers are further configured to determine the measured temperature of the phase switch element using a thermistor of the phase switch element.

[0025] In some aspects, the technology described herein relates to a system wherein the one or more controllers are further configured to control the gate voltage by reducing the gate voltage while maintaining a drain current of the phase switching element above a threshold level.

[0026] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed embodiments, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosed embodiments.

[0028] Figure 1 An exemplary system infrastructure for a vehicle including a combined inverter and converter is depicted according to one or more embodiments.

[0029] Figure 2 Depicted is a method for providing a point-of-use switching controller according to one or more embodiments. Figure 1 An exemplary system infrastructure of a combined inverter and converter.

[0030] Figure 3 Describes a method for Figure 2 An exemplary system infrastructure for a controller of FIG.

[0031] Figure 4 Describes a method for Figure 2 An exemplary system infrastructure for a point-of-use switching controller.

[0032] Figure 5 Describes a method for Figure 4 An exemplary system infrastructure of an upper power module.

[0033] Figure 6 An electrical power schematic diagram of an inverter in a connected system is depicted in accordance with one or more embodiments.

[0034] Figure 7 Depicted are exemplary graphs for changes in drain current with respect to gate voltage and temperature and exemplary graphs for controlling active discharge based on temperature of a power module for an inverter according to one or more embodiments.

[0035] Figure 8 Depicted is an exemplary graph having results of controlling active discharge of power modules of an inverter according to one or more embodiments. DETAILED DESCRIPTION

[0036] Both the foregoing general description and the following detailed description are exemplary and explanatory only and do not constrain the claimed features. As used herein, the terms "comprises," "comprising," "has," "having," "includes," "including," or other variations thereof are intended to encompass non-exclusive inclusions such that a process, method, article, or device that includes a series of elements includes not only those elements, but may also include other elements that are not explicitly listed or inherent to such process, method, article, or device. In the present disclosure, unless otherwise stated, relative terms (such as, for example, "about," "substantially," and "approximately") are used to indicate possible ±10% variations in the stated values. In the present disclosure, unless otherwise stated, any numerical value may include possible ±10% variations in the stated values.

[0037] The terms used below may be interpreted in their broadest reasonable manner, although they are being used in conjunction with a detailed description of certain specific examples of the present disclosure. Indeed, certain terms may even be emphasized below; however, any term intended to be interpreted in any constrained manner will be explicitly and specifically defined as such in this detailed description. For example, in the context of the present disclosure, a switching device may be described as a switching element or device, but may refer to any device for controlling power flow in a circuit. For example, a switching element may be, for example, a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a silicon carbide FET or a relay, or any combination thereof, but is not limited thereto.

[0038] Various embodiments of the present disclosure relate generally to systems and methods for controlling active discharge of an inverter for an electric vehicle, and more particularly to systems and methods for controlling active discharge based on temperature of an inverter for an electric vehicle.

[0039] Inverters (such as those used to drive motors in electric vehicles) are responsible for converting high voltage direct current (HVDC) into alternating current (AC) to drive the motor. A three-phase inverter may include a bridge having six power device switches (e.g., power transistors such as IGBTs or MOSFETs) that are controlled by pulse width modulation (PWM) signals generated by a controller. The inverter may include three half-H-bridge switches to control phase voltages, upper and lower gate drivers to control the switches, a PWM controller, and glue logic between the PWM controller and the gate driver. The PWM controller may generate signals to define the expected state of the system. The gate driver may send signals from the PWM controller to the half-H-bridge switches. The half-H-bridge switches may drive the phase voltages. The inverter may include an isolation barrier between a low voltage plane and a high voltage plane. The signal may be passed from the PWM controller to the half-H-bridge switch by passing through the isolation barrier, which may employ optical, converter-based, or capacitor-based isolation. The PWM signal may be distorted when passing through the glue logic, which may include resistive, capacitive, or other types of filtering. Due to the galvanic isolation barrier and other delays within the gate driver, the PWM signal may be distorted when passing through the gate driver. The PWM signal may be distorted when the signal is processed by the half-H switching element via the gate driver output. Note that six-phase inverters and multi-level inverters are not excluded from this concept and will follow similar principles. This may be introduced in subsequent pages.

[0040] Gate drivers withstand common-mode transients that occur during field effect transistor (FET) switching and when one side of a floating high voltage terminal is shorted to ground or subjected to electrostatic discharge. These voltage transients can cause fast edges that can form common-mode current bursts through electrical isolation. Gate drivers may need to demonstrate common-mode transient immunity (CMTI) in order to be effective and safe.

[0041] The gate driver may have a high voltage domain in common with the voltage plane of the associated FET. Further, the high voltage plane may be supplied by a flyback converter, which may be isolated from the low voltage plane by a transformer. The high voltage domain power supply may be used to provide power to such a circuit that sources and sinks gate current to drive the FET and can detect FET faults, thereby acting on the faults and / or transmitting the faults to the low voltage domain. The gate driver may include an electrical channel dedicated to FET commands, and one or more bidirectional or unidirectional electrical channels dedicated to FET communications.

[0042] High current switching transients can form strong electromagnetic (EM) fields that can couple into nearby metal traces. The magnitude and frequency of the coupled current can depend on the layout of the FET packaging solution and the direction and length of the metal traces between the FET and the control integrated circuit (IC). For example, a typical value for the coupled current can be up to 1A at an AC frequency of up to 100MHz. Typically, within the circuit, the gate driver IC can be placed far enough away from the FET so that the high EM field is not directly coupled into the internal metal traces within the gate driver IC. The gate driver is placed at a distance from the EM field so that the induced current within the circuit is below the level that will cause the gate driver to malfunction, or a metal shield is placed between the gate driver and the source of the EM field to protect the gate driver circuit. The output terminals of the gate driver connected to the FET are exposed to the EM field at a point where the output terminals are no longer covered by the shield. The gate driver switches large currents (e.g., such as 5A to 15A) through these exposed terminals. The large currents switched are usually larger in magnitude than the EM induced current. The gate driver can overdrive the induced current to maintain control of the FET. The gate driver and the high side of the FET may share a common ground and gate control signal trace, both of which may be susceptible to coupled currents.

[0043] The gate driver can turn on low resistance switches to source and sink gate current. Sometimes a series resistor can be added to limit the gate current. The switched gate current can be greater than the coupling current in order to maintain control of their respective FETs.

[0044] The gate driver may be able to sense the FET operating voltage or current in order to provide feedback and react to faults. An overcurrent fault may typically be detected by sensing the FET drain to source voltage and comparing the sensed voltage to a reference value. The sensed voltage may be heavily filtered to reject coupled currents. Filtering may slow the response to a fault condition, causing a delay in response. For example, the rate of current increase due to a low resistance short may reach damaging levels before being detected by a heavily filtered drain to source voltage detection strategy. The resulting short may damage the FET or the vehicle before being detected and cut off.

[0045] According to one or more embodiments, a FET driver circuit may provide fast overcurrent detection by shunt current sensing, or by diverting a portion of the load current through a parallel FET that may have a current sensing circuit. Utilizing either strategy may require a "point of use IC" in which the sensing circuit is very close to the FET. Even if the point of use IC and the remote controller are resistant to EM fields, the communication between the point of use IC and the remote controller is still susceptible to induced currents. Point of use ICs have been implemented in low EM field applications, such as smart FETs for automotive applications. However, point of use ICs have not yet been used in high EM field applications. High EM fields can be fields that (i) induce a current within the IC that exceeds the operating current of the IC and causes a malfunction, or (ii) induce a differential voltage within the IC that exceeds the operating differential voltage and causes a malfunction. High EM fields can be, for example, fields greater than about 10A or about 100V.

[0046] As a result of the system design, a significant amount of energy can be stored on the inverter's high voltage bus bulk / DC bus capacitors. This stored high voltage energy must be dissipated to prevent people from being exposed to dangerous voltage levels. The inverter's function known as "active discharge" allows controlled dissipation of energy stored in the system capacitor. The system capacitor is commonly referred to as a bulk capacitor in an inverter system. Before initiating active discharge of the bus, the high voltage battery that provides energy to the inverter is disconnected to avoid discharging the battery. The active discharge function has the ability to quickly dissipate high voltage bus energy to ensure safety in events such as vehicle maintenance, vehicle collisions, etc. The discharge rate is a function of the initial bus voltage, capacitance, and energy dissipation mechanism. Government / OEM regulations also specify the required discharge rate.

[0047] For example, inverters often have safety requirements to discharge bulk capacitors on the inverter in a short period of time (such as between 1 and 3 seconds) in the event of a crash or other fault condition. Some systems use motor windings to discharge bulk capacitors, which requires that the motor is not shorted and the main microcontroller is available. Some systems use a dedicated resistive discharge to discharge bulk capacitors, which is typically a combination of a high power resistor, a switch, and a controller.

[0048] Therefore, the inverter can use the switching losses in the inverter power device switching elements (IGBT / FET) to release energy. Controlling the power device on / off (also known as enabling / disabling) forms predictable losses. Multiple switching at high frequency rates can cause a significant amount of these accumulated losses. The rate of discharge (loss) can be proportional to the switching frequency. As a backup or without the cost and complexity of using motor windings or dedicated resistor discharges, these losses can be used to quickly discharge the HVDC bus. In addition, by eliminating the resistive elements in traditional methods, a lot of cost, circuit board area and undesirable heat can be saved.

[0049] Some systems use a gate driver to discharge a bulk capacitor to operate a power switch in a half H-bridge switch in linear mode, which effectively uses the power switch as a resistor by controlling the gate positive bias voltage and / or switching. In this method, one power switch (e.g., an upper switch) is turned on as in normal operation, and another power switch (e.g., a lower switch) is pulsed on with a reduced gate voltage. The HVDC bus and bulk capacitors can be discharged via specific PWM pulses. One or more embodiments may use the change in temperature of the current allowed to pass through the power switch. The drain current of the power switch may increase with temperature changes by eight times or more. For example, the temperature change may be due to self-heating of the power switch when in linear mode or the initial temperature of the power switch when the active discharge is initialized. During active discharge, if the temperature is not controlled, the power switch may experience an increase in temperature that is significant enough to cause failure.

[0050] The power switching components may have significant differences in transfer characteristics based on temperature, especially in the linear mode region for which the DC bus is discharged. For example, the temperature difference may be based on the ambient temperature and may include temperatures such as -40C to 100C operating temperature.

[0051] Some systems that use threshold detection to discharge the bulk capacitor (which requires shutting down the opposing device) may choose to increase the sensed threshold by one step (e.g., 390mV) and may have a voltage that is fixed at the beginning of the discharge operation and cannot be changed during the discharge operation. Some systems use a pre-programmed voltage to discharge the bulk capacitor, where the voltage is fixed at power-up during configuration mode and cannot be changed during inverter operation.

[0052] As an example, a specification may explicitly require 4A per die. At a die temperature of 100C, the gate voltage may be 3.08V for a die current of 4A. At a temperature of 25C and a gate voltage of 3.08V, the die current may be 0.8A (approximately 20% of the rated value). At a temperature of 125C and a gate voltage of 3.08V, the die current may be 5.3A (approximately 133% of the rated value). At a temperature of 140C and a gate voltage of 3.08V, the die current may be 5.8A (approximately 145% of the rated value). At a temperature of 175C and a gate voltage of 3.08V, the die current may be 12.13A (approximately 300% of the rated value). Additional errors occur when the drain voltage varies. For example, when the drain to source voltage is 950V, the SiC FET transconductance is much higher, resulting in a significantly higher drain to source current. This must be taken into account during the process of estimating the required gate voltage.

[0053] One or more embodiments may provide an active discharge system that includes temperature feedback by indirect estimation or direct measurement. One or more embodiments may reduce the gate voltage while maintaining the drain current within a range that allows the discharge to be performed in a timely manner while protecting the power switching device from high temperatures. For indirect estimation, at any given gate voltage, the drain current may be known for a certain temperature range. Therefore, by measuring the drain current and using the applied gate voltage, the temperature of the power switching device can be estimated and used as feedback to adjust the gate voltage. For example, the current sensor may include one or more of an integrated current sensor, a shunt resistor, or an integrated Rogowski coil.

[0054] The point-of-use controller may be on a power module that includes a phase switch. The temperature of the phase switch and / or the power module may be an important factor in the control of the inverter. The phase switch may include, for example, one or more silicon carbide (SiC) grains. One or more embodiments may include a thermistor to monitor the SiC grain temperature. For example, one or more embodiments may include a point-of-use controller, such as an integrated gate driver ASIC. The ASIC may use an on-chip integrated trimmed thermal sensor to accurately measure the temperature. Both the SiC gate threshold voltage and transconductance decrease with temperature.

[0055] One or more embodiments may allow temperature-based control of the power module during bulk capacitor discharge. Bulk capacitor discharge at shutdown is a function in which the bulk capacitor is quickly discharged after the battery contactor is opened. The bulk capacitor discharge reduces the risk of contact with high voltage. Bulk capacitor discharge can transfer energy from the bulk capacitor (e.g., 700μF*800V2) to the power switching element and should be implemented in a controlled manner. Using the temperature of the SiC device during bulk capacitor discharge can reduce the discharge time while protecting the SiC device from excessive temperature rise.

[0056] One or more embodiments may measure the temperature of the die measured before the inverter active discharge begins and use the measured temperature to select the correct gate voltage for active discharge. One or more embodiments may monitor the die temperature during active discharge operation to further adjust the gate voltage, and therefore adjust the power dissipation in the SiC die and the resulting active discharge rate. As previously described, the current flowing through each half of the half H-bridge may not be measured in a SiC implementation and may be estimated using temperature and characterization data obtained during the manufacture of the power switching device. The phase current may be measured, but may not indicate the current through the lower switching device of the upper switching device during active discharge. One or more embodiments may modify the gate voltage based on the die temperature and adjust the active discharge operation based on the temperature.

[0057] Accurately knowing the temperature of SiC devices within a power module may allow the reliability and efficiency of the power module to be optimized. One or more embodiments may provide a power module that incorporates a SiC FET bare die and an integrated gate driver ASIC. Accurate temperature sensing of the SiC FET bare die may allow the cost and efficiency of the overall system to be optimized. Some systems may use a thermistor placed within the power module. The thermistor allows the temperature to be measured in the physical location of the thermistor. One or more embodiments may provide an apparatus and method for accurately estimating the temperature of SiC devices within a power module. One or more embodiments may provide a gate driver ASIC that is integrated into the power module together with the bare die.

[0058] One or more embodiments may provide an integrated gate driver within a power module. The integrated gate driver may be an ASIC. The ASIC may include two thermal sensors on the ASIC. The thermal sensor may be composed of a stack of diodes having a voltage drop with a negative temperature coefficient. However, the present disclosure is not limited thereto and may include other ways of constructing a thermal sensor within an ASIC.

[0059] One or more embodiments may provide a thermal measurement device including a diode stack and an analog-to-digital converter (ADC). However, the present disclosure is not limited thereto. One or more embodiments may provide a system for accurately estimating the temperature of adjacent SiC die located within a power module. One or more embodiments may provide a system with improved accuracy that may allow optimization of system design due to reduced error tolerance.

[0060] Figure 1 An exemplary system infrastructure for a vehicle including a combined inverter and converter according to one or more embodiments is depicted. In the context of the present disclosure, the combined inverter and converter may be referred to as an inverter. Figure 1 As shown, the electric vehicle 100 may include an inverter 110, a motor 190, and a battery 195. The inverter 110 may include a component for receiving electric power from an external source and outputting electric power to charge the battery 195 of the electric vehicle 100. For example, the inverter 110 may convert DC power from the battery 195 in the electric vehicle 100 into AC power to drive the motor 190 of the electric vehicle 100, but the embodiment is not limited thereto. For example, the inverter 110 may be bidirectional and may convert DC power into AC power, or convert AC power into DC power, such as during regenerative braking. The inverter 110 may be a three-phase inverter, a single-phase inverter, or a multi-phase inverter.

[0061] Figure 2 Depicted is a method for providing a point-of-use switching controller according to one or more embodiments. Figure 1 The electric vehicle 100 may include an inverter 110, a motor 190, and a battery 195. The inverter 110 may include an inverter controller 300 ( Figure 314). The inverter 110 may include a low voltage upper phase controller 120 separated from a high voltage upper phase controller 130 by an electrical isolator 150, and an upper phase power module 140. The upper phase power module 140 may include a point-of-use upper phase controller 142 and an upper phase switch 144. The inverter 110 may include a low voltage lower phase controller 125 separated from a high voltage lower phase controller 135 by an electrical isolator 150, and a lower phase power module 145. The lower phase power module 145 may include a point-of-use lower phase controller 146 and a lower phase switch 148. The upper phase switch 144 and the lower phase switch 148 may be connected to a motor 190 and a battery 195. The electrical isolator 150 may be one or more of optical, converter-based, or capacitor-based isolation. For example, the electrical isolator 150 may be one or more capacitors having a value from about 20 fF to about 100 fF, having a breakdown voltage from about 6 kV to about 12 kV. The electrical isolator 150 may include a pair of capacitors, wherein one capacitor in the pair carries an inverted data signal from the other capacitor in the pair to form a differential signal that is rejected for common mode noise. The electrical isolator 150 may include more than one capacitor in series. The electrical isolator 150 may include one capacitor located on a first IC, or may include a first capacitor located on a first IC and a second capacitor located on a second IC that communicates with the first IC.

[0062] The inverter 110 may include a low voltage region (e.g., where the voltage is typically less than 5V) and a high voltage region (e.g., where the voltage may exceed 500V). The low voltage region may be separated from the high voltage region by an electrical isolator 150. The inverter controller 300 may be in the low voltage region of the inverter 110, and may send a signal to and receive a signal from the low voltage upper phase controller 120. The low voltage upper phase controller 120 may be in the low voltage region of the inverter 110, and may send a signal to and receive a signal from the high voltage upper phase controller 130. The low voltage upper phase controller 120 may send a signal to and receive a signal from the low voltage lower phase controller 125. The high voltage upper phase controller 130 may be in the high voltage region of the inverter 110. Therefore, the signal between the low voltage upper phase controller 120 and the high voltage upper phase controller 130 passes through the electrical isolator 150. The high voltage upper phase controller 130 may send signals to and receive signals from a point-of-use upper phase controller 142 in the upper phase power module 140. The point-of-use upper phase controller 142 may send signals to and receive signals from an upper phase switch 144. The upper phase switch 144 may be connected to a motor 190 and a battery 195. For example, the upper phase switch 144 and the lower phase switch 148 may be used to transfer energy from the motor 190 to the battery 195, from the battery 195 to the motor 190, from an external source to the battery 195, or from the battery 195 to an external source. The lower phase system of the inverter 110 may be similar to the upper phase system described above.

[0063] Figure 3 Describes a method for Figure 2 FIG. 3 is an exemplary system infrastructure of an inverter controller 300 . The inverter controller 300 may include one or more controllers.

[0064] The inverter controller 300 may include a set of instructions that can be executed to cause the inverter controller 300 to perform any one or more of the methods or computer-based functions disclosed herein. The inverter controller 300 may operate as a standalone device, or may be connected to other computer systems or peripheral devices, for example using a network.

[0065] In a networked deployment, the inverter controller 300 can operate in the capacity of a server, or as a client in a server-client user network environment, or as a peer computer system in a peer (or distributed) network environment. The inverter controller 300 can also be implemented as or incorporated into various devices, such as a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile device, a palmtop computer, a laptop computer, a desktop computer, a communication device, a wireless phone, a landline phone, a control system, a camera, a scanner, a fax machine, a printer, a pager, a personal trusted device, a network device, a network router, a switch or bridge, or any other machine capable of executing a set of instructions (sequentially or otherwise) (the set of instructions specifies the actions to be taken by the machine). In a specific implementation, the inverter controller 300 can be implemented using an electronic device that provides voice, video or data communication. Further, although the inverter controller 300 is illustrated as a single system, the term “system” should also be understood to include any collection of systems or subsystems that individually or jointly execute one or more sets of instructions to perform one or more computer functions.

[0066] like Figure 3 As shown, the inverter controller 300 may include a processor 302, such as a central processing unit (CPU), a graphics processing unit (GPU), or both. The processor 302 may be a component in a variety of systems. For example, the processor 302 may be part of a standard inverter. The processor 302 may be one or more general-purpose processors, digital signal processors, application-specific integrated circuits, field programmable gate arrays, servers, networks, digital circuits, analog circuits, combinations thereof, or other devices now known or later developed for analyzing and processing data. The processor 302 may implement a software program, such as a manually generated (i.e., programmed) code.

[0067] The inverter controller 300 may include a memory 304 that can communicate via a bus 308. The memory 304 may be a main memory, a static memory, or a dynamic memory. The memory 304 may include, but is not limited to, computer-readable storage media, such as various types of volatile and non-volatile storage media, including but not limited to random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, tape or disk, optical media, etc. In one specific implementation, the memory 304 includes a cache or random access memory for the processor 302. In an alternative specific implementation, the memory 304 is separated from the processor 302, such as a cache memory, system memory, or other memory of the processor. The memory 304 may be an external storage device or database for storing data. Examples include a hard drive, a compact disk ("CD"), a digital video disk ("DVD"), a memory card, a memory stick, a floppy disk, a universal serial bus ("USB") storage device, or any other device operable to store data. The memory 304 is operable to store instructions that can be executed by the processor 302. The functions, actions, or tasks illustrated in the figures or described herein may be performed by the processor 302 executing instructions stored in the memory 304. The functions, actions, or tasks are not related to a particular type of instruction set, storage medium, processor, or processing strategy, and may be performed by software, hardware, integrated circuits, firmware, microcode, etc. operating alone or in combination. Likewise, processing strategies may include multi-processing, multi-tasking, parallel processing, etc.

[0068] As shown, the inverter controller 300 may further include a display 310, such as a liquid crystal display (LCD), an organic light emitting diode (OLED), a flat panel display, a solid state display, a cathode ray tube (CRT), a projector, a printer, or other display devices known now or later developed for outputting the determined information. The display 310 may serve as an interface for a user to view the operation of the processor 302, or specifically serve as an interface with the software stored in the memory 304 or in the drive unit 306.

[0069] Additionally or alternatively, the inverter controller 300 may include an input device 312 configured to allow a user to interact with any of the components of the inverter controller 300. The input device 312 may be a numeric keypad, a keyboard or a cursor control device (such as a mouse or a joystick), a touch screen display, a remote control, or any other device operable to interact with the inverter controller 300.

[0070] The inverter controller 300 may also or alternatively include a drive unit 306 implemented as a disk or optical drive. The drive unit 306 may include a computer-readable medium 322 in which one or more sets of instructions 324 (e.g., software) may be embedded. Further, the instructions 324 may embody one or more of the methods or logics described herein. The instructions 324 may reside completely or partially within the memory 304 and / or within the processor 302 during execution by the inverter controller 300. The memory 304 and the processor 302 may also include computer-readable media as described above.

[0071] In some systems, the computer-readable medium 322 includes instructions 324 or receives and executes instructions 324 in response to a propagated signal, so that a device connected to the network 370 can transmit voice, video, audio, images, or any other data through the network 370. Further, the instructions 324 can be transmitted or received through the network 370 and / or using the bus 308 via the communication port or interface 320. The communication port or interface 320 can be part of the processor 302 or can be an independent component. The communication port or interface 320 can be formed in software or can be a physical connector in hardware. The communication port or interface 320 can be configured to connect to the network 370, external media, display 310, or any other component in the inverter controller 300, or a combination thereof. The connection to the network 370 can be a physical connection (such as a wired Ethernet connection) or can be established wirelessly, as described below. Similarly, additional connections to other components of the inverter controller 300 can be physical connections or can be established wirelessly. The network 370 can alternatively be directly connected to the bus 308.

[0072] Although the computer-readable medium 322 is shown as a single medium, the term "computer-readable medium" may include a single medium or multiple media (such as a centralized or distributed database and / or associated caches and servers) that store one or more sets of instructions. The term "computer-readable medium" may also include any medium capable of storing, encoding, or carrying a set of instructions for execution by a processor or causing a computer system to perform any one or more of the methods or operations disclosed herein. The computer-readable medium 322 may be non-transitory and may be tangible.

[0073] Computer readable medium 322 may include solid-state memory, such as a memory card or other package that accommodates one or more non-volatile read-only memories. Computer readable medium 322 may be random access memory or other volatile rewritable memory. Additionally or alternatively, computer readable medium 322 may include magneto-optical or optical media, such as a disk or tape or other storage device for capturing carrier signals (such as signals transmitted through a transmission medium). Digital file attachments to e-mails or other self-contained information archives or archive sets may be considered distribution media as tangible storage media. Therefore, the present disclosure is considered to include any one or more of computer-readable media or distribution media and other equivalents and successor media in which data or instructions may be stored.

[0074] In alternative implementations, dedicated hardware implementations (such as application specific integrated circuits, programmable logic arrays, and other hardware devices) may be constructed to implement one or more of the methods described herein. Applications that may include the apparatus and systems of various implementations may broadly include a variety of electronic and computer systems. One or more implementations described herein may use two or more specific interconnected hardware modules or devices with associated control and data signals that may be transmitted between and through the modules or as part of an application specific integrated circuit to implement functionality. Thus, the present system encompasses software, firmware, and hardware implementations.

[0075] The inverter controller 300 may be connected to a network 370. The network 370 may define one or more networks, including wired or wireless networks. The wireless network may be a cellular telephone network, an 802.11, 802.16, 802.20, or WiMAX network. Further, such networks may include public networks (such as the Internet), private networks (such as intranets), or combinations thereof and may utilize a variety of networking protocols that are now available or later developed, including but not limited to TCP / IP-based networking protocols. The network 370 may include a wide area network (WAN) (such as the Internet), a local area network (LAN), a campus area network, a metropolitan area network, a direct connection (such as through a universal serial bus (USB) port), or any other network that allows data communication. The network 370 may be configured to couple one computing device to another computing device to enable data communication between devices. The network 370 may generally be enabled to use any form of machine-readable media to transmit information from one device to another. The network 370 may include a communication method by which information can travel between computing devices. The network 370 may be divided into subnetworks. A subnetwork may allow access to all other components connected to it, or a subnetwork may restrict access between components. Network 370 may be considered a public or private network connection and may include, for example, a virtual private network or encryption or other security mechanisms employed over the public Internet.

[0076] According to various implementations of the present disclosure, the methods described herein may be implemented by a software program that can be executed by a computer system. Further, in an exemplary non-limiting implementation, the implementation may include distributed processing, component or object distributed processing, and parallel processing. Alternatively, a virtual computer system process may be constructed to implement one or more of the methods or functionalities described herein.

[0077] Although this specification describes components and functions that can be implemented in a specific implementation with reference to specific standards and protocols, the present disclosure is not limited to such standards and protocols. For example, standards for Internet and other packet-switched network transmissions (e.g., TCP / IP, UDP / IP, HTML, HTTP) represent examples of the prior art. Such standards are periodically replaced by faster or more efficient equivalents having substantially the same functionality. Therefore, alternative standards and protocols having the same or similar functionality as those disclosed herein are considered equivalents thereof.

[0078] It will be appreciated that, in one embodiment, the operations of the methods discussed are performed by an appropriate processor (or processors) of a processing (i.e., computer) system executing instructions (computer readable code) stored in a storage device. It will also be appreciated that the present disclosure is not limited to any particular implementation or programming technique, and that the present disclosure may be implemented using any suitable technique for implementing the functionality described herein. The present disclosure is not limited to any particular programming language or operating system.

[0079] Figure 4 Describes a method for Figure 2 An exemplary system infrastructure of a point-of-use switching controller. For a three-phase inverter, each of the upper phase and the lower phase may include three phases related to phases A, B, and C. For example, the upper phase power module 140 may include an upper phase power module 140A for upper phase A, an upper phase power module 140B for upper phase B, and an upper phase power module 140C for upper phase C. The upper phase power module 140A may include a point-of-use upper phase A controller 142A and an upper phase A switching element 144A. The upper phase power module 140B may include a point-of-use upper phase B controller 142B and an upper phase B switching element 144B. The upper phase power module 140C may include a point-of-use upper phase C controller 142C and an upper phase C switching element 144C. Each of the upper phase A switching member 144A, the upper phase B switching member 144B, and the upper phase C switching member 144C may be connected to the motor 190 and the battery 195 . Figure 4 Details of the upper phase power module 140 are depicted. Although not shown, the lower phase power module 145 may include a similar structure as the upper phase power module 140 for the lower phases A, B, and C.

[0080] Figure 5 Describes a method for Figure 4 Example system infrastructure for the upper power module. For example, Figure 5 Additional details of upper phase power module 140A are provided. Although not shown, upper phase power module 140B, upper phase power module 140C, and respective lower phase power modules of lower phase power module 145 may include components related to Figure 5 The upper phase power module 140A shown in FIG. 1 is similar in structure to the upper phase power module 140A shown in FIG. 1. In addition, the terms "upper", "lower", "northern", and "southern" as used in this disclosure are used for reference only, do not limit the elements to a particular orientation, and are generally interchangeable throughout the text. For example, the upper phase power module 140 may be referred to as a lower phase power module, a northern phase power module, a southern phase power module, a first phase power module, or a second phase power module.

[0081] The upper phase power module 140A may include a point-of-use upper phase A controller 142A and an upper phase A switch 144A. The upper phase A switch 144A may include one or more sets of switches. Figure 5 As shown, the upper phase A switch 144A may include an upper phase A north switch 144A-N and an upper phase A south switch 144A-S. The point-of-use upper phase A controller 142A may include one or more memories, controllers, or sensors. For example, the point-of-use upper phase A controller 142A may include a communication manager 405, a functional safety controller 410, a test interface and controller 415, a north thermal sensor 420A, a south thermal sensor 420B, a self-test controller 425, a command manager 430, a waveform adjuster 435, a memory 440, a north switch control and diagnostic controller 450N, and a south switch control and diagnostic controller 450S. The point-of-use upper phase A controller 142A may include a controller 405, a functional safety controller 410, a test interface and controller 415, a north thermal sensor 420A, a south thermal sensor 420B, a self-test controller 425, a command manager 430, a waveform adjuster 435, a memory 440, a north switch control and diagnostic controller 450N, and a south switch control and diagnostic controller 450S. Figure 5 More or fewer components than those shown. For example, the point-of-use upper phase A controller 142A may include more or less than two switch controls and diagnostic controllers, and may include more than two thermal sensors.

[0082] The communication manager 405 may control inter-controller communications to and from the point-of-use upper phase A controller 142A and / or may control intra-controller communications between components of the point-of-use upper phase A controller 142A. The functional safety controller 410 may control safety functions of the point-of-use upper phase A controller 142A. For example, the test interface and controller 415 may control test functions of the point-of-use upper phase A controller 142A, such as end-of-line testing in manufacturing. The north thermal sensor 420A may sense the temperature at a first location in the point-of-use upper phase A controller 142A, and the south thermal sensor 420B may sense the temperature at a second location in the point-of-use upper phase A controller 142A. For example, the self-test controller 425 may control self-test functions of the point-of-use upper phase A controller 142A, such as during initialization of the point-of-use upper phase A controller 142A after an inverter 110 power-on event. The command manager 430 may control commands received from the communication manager 405 and issued to the north switch control and diagnostic controller 450N and the south switch control and diagnostic controller 450S. The waveform adjuster 435 may control the waveform timing and shape of the commands received from the communication manager 405 and issued to the north switch control and diagnostic controller 450N and the south switch control and diagnostic controller 450S. The memory 440 may include one or more volatile and non-volatile storage media for the operation of the point-of-use upper phase A controller 142A. The north switch control and diagnostic controller 450N may send one or more signals to the north switch 144A-N to control the operation of the north switch 144A-N, and may receive one or more signals from the north switch 144A-N that provide information about the north switch 144A-N. The south switch control and diagnostic controller 450S may send one or more signals to the south switches 144A-S to control the operation of the south switches 144A-S, and may receive one or more signals from the south switches 144A-S providing information about the south switches 144A-S. As described above, the terms "north" and "south" are used for reference only, and the north switch control and diagnostic controller 450N may send one or more signals to the south switches 144A-S, and the south switch control and diagnostic controller 450S may send one or more signals to the south switches 144A-N.

[0083] Figure 6 An electrical power schematic diagram of an inverter in a connected system according to one or more embodiments is depicted. For example, the inverter may be used to convert DC power from a battery in an electric vehicle to AC power to drive an electric motor of the electric vehicle, but embodiments are not limited thereto. Additionally, the inverter may be bidirectional and used to convert DC power to AC power or to convert AC power to DC power.

[0084] like Figure 6 As shown, the inverter 110 may be connected to a battery 195 (DC power source) and a motor 190. The inverter 110 may include an upper phase switching element 144 and a lower phase switching element 148. The first phase (ΦA) may include switching elements Q1 and Q4, the second phase (ΦB) may include switching elements Q3 and Q6, and the third phase (ΦC) may include switching elements Q5 and Q2, as shown in FIG. Figure 6 As shown. The upper phase switching element 144 may include a first phase switching element Q1, a second phase switching element Q3, and a third phase switching element Q5. The lower phase switching element 148 may include a first phase switching element Q4, a second phase switching element Q6, and a third phase switching element Q2. For example, the switching elements Q1 to Q6 may be metal oxide semiconductor field effect transistors (MOSFETs), but are not limited thereto.

[0085] The upper phase switching element 144 and the lower phase switching element 148 can be controlled by the inverter controller 300 ( Figure 3 ) to convert the DC power delivered via the set of input terminals 685 at the bulk capacitor 630 into three-phase AC power at the outputs U, V and W (associated with phases A, B and C, respectively) to the motor 190 via the set of output terminals 695. In addition, although Figure 6 A three-phase inverter is illustrated, but the present disclosure is not limited thereto and may include a single-phase or multi-phase or multi-level inverter.

[0086] As a result of the system design, a significant amount of energy can be stored on the bulk capacitor 630 of the inverter 110. This stored high voltage energy must be dissipated to prevent people from being exposed to dangerous voltage levels. A function of the inverter known as "active discharge" allows controlled dissipation of the energy stored in the bulk capacitor 630. Before initiating active discharge of the bus, the battery 195 that provides energy to the inverter 110 is disconnected to avoid discharging the battery 195. The active discharge function has the ability to quickly dissipate high voltage bus energy to ensure safety in events such as vehicle maintenance, vehicle collisions, etc. The discharge rate is a function of the initial bus voltage, capacitance, and energy dissipation mechanism. Government / OEM regulations also specify the required discharge rate.

[0087] For example, the inverter 110 may have a safety requirement to discharge the bulk capacitor 630 on the inverter 110 within a short period of time (such as between 1 second and 3 seconds) in the event of a crash or other fault condition. The inverter 110 does not use the windings of the motor 190 to discharge the bulk capacitor 630, which requires that the motor 190 is not short-circuited and the inverter controller 300 is available. The inverter 110 does not use a dedicated resistor discharge to discharge the bulk capacitor 630, and does not require a high power resistor with associated switching and control.

[0088] Therefore, the inverter 110 can use the switching losses in the upper phase switching element 144 and the lower phase switching element 148 to release the energy in the large-capacity capacitor 630. Controlling the upper phase switching element 144 and the lower phase switching element 148 to turn on / off (also referred to as enabling / disabling) forms a predictable loss. Switching multiple times at a high frequency rate can cause a significant amount of these accumulated losses. The rate of discharge (loss) can be proportional to the switching frequency. Without increasing the cost and complexity of using motor windings or dedicated resistors to discharge, these losses can be used to quickly discharge the large-capacity capacitor 630 and the HVDC bus. In addition, by eliminating the resistive elements in the traditional method, a large amount of cost, circuit board area and undesirable heat can be saved.

[0089] The inverter 110 can discharge the bulk capacitor 630 using a gate driver (e.g., an isolated gate driver, a point-of-use upper phase controller 142, a point-of-use lower phase controller 146) in linear mode to operate one of the phase (power) switches in the upper phase switch 144 and the lower phase switch 148, which effectively uses the power switch as a resistor by controlling the gate positive bias voltage and / or switching. In this method, one power switch (e.g., Q1) is turned on as in normal operation, and the other power switch (e.g., Q4) is pulsed on with a reduced gate voltage. The HVDC bus and bulk capacitor 630 can be discharged via specific PWM pulses.

[0090] Figure 7 Depicted are an exemplary graph 705 for changes in drain current with respect to gate voltage and temperature and an exemplary graph 710 for controlling active discharge based on temperature of a power module for an inverter according to one or more embodiments.

[0091] As shown in graph 705, for example, at a gate voltage of 4.5 volts, the die current for active discharge without temperature usage may range from about 12 A at 25 C to 45 A at 140 C. As shown in graph 710, for example, at a gate voltage of 4.5 volts, the die current for active discharge based on temperature may range from about 4 A at 25 C to 14 A at 150 C.

[0092] Figure 8 Depicted is an exemplary graph having results of controlling active discharge of power modules of an inverter according to one or more embodiments.

[0093] The result graph 800 depicts the variation of VccH (drain current) 805, DC voltage 810, upper gate voltage 815, and lower gate voltage 820 over time. The result graph 800 depicts a test of a 550 μF bulk capacitor at 880V and at room temperature without coolant. The result graph 800 shows a peak current of approximately 300A, a final current of approximately 100A, and a discharge time of approximately 142ms. The gate was switched at 5kHz and a 6.4μs on time.

[0094] One or more embodiments may use the variation of the current allowed to pass through the power switch with temperature. One or more embodiments may provide an active discharge system that includes temperature feedback through indirect estimation or direct measurement. One or more embodiments may reduce the gate voltage while keeping the drain current within a range that allows the discharge to be performed in a timely manner while protecting the power switch from high temperatures.

[0095] One or more embodiments may include a thermistor to monitor SiC die temperature. For example, one or more embodiments may include a point-of-use controller, such as an integrated gate driver ASIC. One or more embodiments may allow for temperature-based control of the power module during bulk capacitor discharge. Using the temperature of the SiC device during bulk capacitor discharge may reduce discharge time while protecting the SiC device from excessive temperature rise.

[0096] One or more embodiments may provide a power module incorporating a SiC FET bare die and an integrated gate driver ASIC. One or more embodiments may provide an apparatus and method for accurately estimating the temperature of a SiC device within a power module. One or more embodiments may provide a gate driver ASIC that is integrated into a power module along with the bare die.

[0097] One or more embodiments may provide an integrated gate driver within a power module. One or more embodiments may provide a thermal measurement device including a diode stack and an analog-to-digital converter (ADC). One or more embodiments may provide a system for accurately estimating the temperature of adjacent SiC die within a power module. One or more embodiments may provide a system with improved accuracy that may allow optimization of system design due to reduced error tolerances.

[0098] According to an embodiment, the inverter does not use a resistor element or a resistor group for active discharge of the inverter. According to an embodiment, the inverter does not use a winding of a motor for active discharge of the inverter.

[0099] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

Claims

1. A system comprising: An inverter configured to convert DC power from a battery into AC power to drive a motor, wherein the inverter comprises: Large-capacity capacitors; one or more phase switching elements; and One or more controllers configured to control a gate voltage to the one or more phase switches to discharge the bulk capacitor, wherein the one or more controllers are configured to control the gate voltage based on one or more of a measured temperature of the one or more phase switches or an estimated temperature of the one or more phase switches.

2. The system of claim 1, wherein the one or more controllers are point-of-use controllers. 3 . The system of claim 1 , wherein the one or more controllers are gate drivers for the one or more phase switches. 4 . The system of claim 1 , wherein the one or more phase switching elements comprise one or more silicon carbide grains. 5 . The system of claim 1 , wherein the one or more controllers include one or more thermal sensors for measuring a temperature of the one or more phase switching elements.

6. The system of claim 1, wherein the inverter further comprises: One or more thermistors for measuring the temperature of the one or more phase switching elements. 7 . The system of claim 1 , wherein the one or more controllers are further configured to control the gate voltage based on a measured temperature of the one or more phase switching elements measured prior to active discharge of the inverter.

8. The system of claim 1, further comprising: the battery, the battery being configured to supply the DC power to the inverter; as well as The motor is configured to receive the AC power from the inverter to drive the motor.

9. A system comprising: a power module for an inverter configured to convert DC power into AC power, the power module comprising a drain terminal and a source terminal; one or more phase switches configured to control current flow between the drain terminal and the source terminal; as well as A point-of-use controller is configured to control a gate voltage to the one or more phase switching elements to discharge a bulk capacitor of the inverter, wherein the point-of-use controller is configured to control the gate voltage based on one or more of a measured temperature of the one or more phase switching elements or an estimated temperature of the one or more phase switching elements.

10. The system of claim 9, wherein the point-of-use controller is an application specific integrated circuit gate driver for the one or more phase switches.

11. The system of claim 9, wherein the one or more phase switching elements comprise one or more silicon carbide grains.

12. The system of claim 9, wherein the point of use controller comprises one or more thermal sensors for measuring a temperature of the one or more phase switching elements.

13. The system of claim 9, wherein the point of use controller is further configured to control the gate voltage based on a measured temperature of the one or more phase switching elements measured prior to active discharge of the inverter.

14. The system of claim 9, wherein the point of use controller is further configured to control the gate voltage by reducing the gate voltage while maintaining a drain current of the one or more phase switching elements above a threshold level.

15. A system comprising one or more controllers, the one or more controllers being configured to: determining one or more of a measured temperature of a phase switching element or an estimated temperature of the phase switching element; and A gate voltage to the phase switch is controlled to discharge a bulk capacitor of an inverter, wherein the one or more controllers are configured to control the gate voltage based on one or more of a measured temperature of the phase switch or an estimated temperature of the phase switch.

16. The system of claim 15, wherein the one or more controllers are point-of-use controllers.

17. The system of claim 15, wherein the one or more controllers are further configured to: A thermal sensor of the one or more controllers is used to determine a measured temperature of the phase switch.

18. The system of claim 15, wherein the one or more controllers are further configured to: The gate voltage is controlled based on a measured temperature of the phase switching device measured prior to active discharge of the inverter.

19. The system of claim 15, wherein the one or more controllers are further configured to: A thermistor of the phase switching element is used to determine a measured temperature of the phase switching element.

20. The system of claim 15, wherein the one or more controllers are further configured to: The gate voltage is controlled by reducing the gate voltage while maintaining a drain current of the phase switching element above a threshold level.

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