Digital Control System for Energy Storage Converter Based on SiC Power Devices

Abstract

This invention provides a digital control system for an energy storage converter based on SiC power devices, including an energy storage converter, an MCU control system, and control circuitry. The control circuitry includes an ultra-high frequency switch drive module, a sampling feedback module, a comprehensive protection module, and a system communication module. The energy storage converter is based on SiC power devices and includes a DC / AC main circuit, a DC / DC main circuit, and a battery pack module. The sampling feedback module collects the current and voltage values ​​of the battery pack module and the current and voltage values ​​of the DC bus between the DC / DC main circuit and the DC / AC main circuit. The MCU control system adjusts the output control signal using a PID algorithm based on the collected current and voltage values, and controls the operating state of the SiC power devices in the energy storage converter through the ultra-high frequency switch drive module. This control system integrates ultra-high frequency switch drive capability, excellent equipment protection performance, and fully digital control, and possesses good control accuracy and response speed.

Description

Technical Field

[0001] This invention relates to the field of energy storage equipment technology, and more specifically, to a digital control system for an energy storage converter based on SiC power devices. Background Technology

[0002] As one of the core components of an energy storage system, the energy storage converter undertakes the key task of power conversion. The high-quality development of new energy in the new era has put forward high-efficiency, advanced and energy-saving requirements for the power conversion efficiency of energy storage converters.

[0003] Existing energy storage converters almost entirely employ Si-based power devices, whose switching performance is nearing its theoretical limit determined by the material properties. The scope for further improving the operating frequency, reducing temperature rise, and improving losses by relying on power devices is extremely limited, severely restricting the improvement of power density and energy efficiency. The use of SiC power devices (wide bandgap power devices) can overcome the bottleneck of limited power density and efficiency improvements in existing energy storage converters due to the constraints imposed by Si-based power devices. However, SiC-based energy storage converters are characterized by high-frequency, high-voltage operation and rapid response, resulting in numerous interference factors and significant control challenges, requiring a high-performance digital control system for precise control. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies in the existing technology, the purpose of this invention is to provide a digital control system for an energy storage converter based on SiC power devices. This control system integrates ultra-high frequency switching drive capability, excellent equipment protection performance, and fully digital control, and has good control accuracy and response speed.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a digital control system for an energy storage converter based on SiC power devices, comprising an energy storage converter, an MCU control system, and a control circuit;

[0006] The control circuit includes an ultra-high frequency switch drive module, a sampling feedback module, a comprehensive protection module for protection in case of fault, and a system communication module for communication with the EMS system and the BMS system.

[0007] The energy storage converter refers to an energy storage converter based on SiC power devices; the energy storage converter includes a DC / AC main circuit for converting current between DC and AC, two or more DC / DC main circuits for transforming and isolating DC power, and a battery pack module; the DC / AC main circuits are connected to the DC / DC main circuits through a DC bus; each DC / DC main circuit is connected to the battery pack module.

[0008] The sampling feedback module collects the current and voltage values ​​of the battery pack module and the DC bus between the DC / DC main circuit and the DC / AC main circuit, and sends the collected current and voltage values ​​to the MCU control system. The MCU control system adjusts the output control signal according to the collected current and voltage values ​​using a PID algorithm, and controls the working state of the SiC power devices of the energy storage converter through the ultra-high frequency switching drive module.

[0009] Preferably, each DC / DC main circuit includes a SiC full-bridge primary module, a high-frequency transformer T201, and a SiC full-bridge secondary module connected in sequence; wherein, the SiC full-bridge primary module is connected to the DC / AC main circuit through a DC bus; the SiC full-bridge primary module and the SiC full-bridge secondary module respectively adopt a full-bridge topology formed by SiC MOSFETs;

[0010] The three-phase AC power grid and the battery module achieve bidirectional energy transfer through the connected DC / AC main circuit and DC / DC main circuit.

[0011] When energy is transferred from the three-phase AC grid to the battery module, the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the input side, and the battery module is the output side. The SiC full-bridge primary module forms an inverter circuit, and the SiC full-bridge secondary module forms a rectifier circuit. When energy is transferred from the battery module to the three-phase AC grid, the battery module is the input side, and the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the output side. The SiC full-bridge secondary module forms an inverter circuit, and the SiC full-bridge primary module forms a rectifier circuit.

[0012] For the inverter circuit, the ultra-high frequency switching drive module outputs two complementary PWM signals with dead time to control the two diagonally opposite SiC MOSFETs of the inverter circuit to simultaneously turn on or off at high frequency, converting DC power into high frequency AC power.

[0013] For the rectifier circuit, the ultra-high frequency switching drive module turns off all SiC MOSFETs; the high-frequency AC power is rectified by the rectifier circuit composed of the body diodes of the SiC MOSFETs.

[0014] Preferably, the MCU control system adjusts the output control signal using a PID algorithm based on the acquired current and voltage values. This means: based on the acquired measured current and voltage values ​​from the output side; performing difference calculations with preset current and voltage setpoints on the output side respectively; and performing PID calculations on the average difference values ​​several times to obtain current and voltage fluctuation values; and changing the on and off times of the SiC MOSFETs in the inverter circuit based on the current and voltage fluctuation values ​​to achieve duty cycle adjustment, so that the current and voltage values ​​on the output side approximate the current and voltage setpoints respectively.

[0015] Preferably, the SiC full-bridge primary module includes SiC MOSFETs M201 to M204; the SiC full-bridge primary module also includes a capacitor C200.

[0016] The SiC MOSFET M201 and SiC MOSFET M203 are connected in series, and together with the SiC MOSFET M202 and SiC MOSFET M204 connected in series, they form a circuit that is connected in parallel to the DC / AC main circuit via the DC bus. The connection between SiC MOSFET M201 and SiC MOSFET M203 is connected to the primary first input terminal of the high-frequency transformer T201 through capacitor C200. The connection between SiC MOSFET M202 and SiC MOSFET M204 is connected to the primary second input terminal of the high-frequency transformer T201.

[0017] The SiC full-bridge secondary module includes SiC MOSFETs M205 to M208; the SiC full-bridge secondary module also includes capacitor C209.

[0018] The SiC MOSFET M205 and SiC MOSFET M207 are connected in series, and together with the circuit formed by the series connection of SiC MOSFET M206 and SiC MOSFET M208, they are connected in parallel to the battery module. The connection between SiC MOSFET M205 and SiC MOSFET M207 is connected to the first output terminal of the secondary winding of the high-frequency transformer T201 through capacitor C209. The connection between SiC MOSFET M206 and SiC MOSFET M208 is connected to the second output terminal of the secondary winding of the high-frequency transformer T201.

[0019] Preferably, the SiC full-bridge secondary module further includes inductors L201 and L202; the connection between SiC MOSFET M201 and SiC MOSFET M203 is connected to the first input terminal of the primary of high-frequency transformer T201 through a series capacitor C200 and inductor L201; inductor L202 is connected in parallel to the primary of high-frequency transformer T201.

[0020] The SiC full-bridge secondary module also includes an inductor L203; a circuit formed by SiC MOSFETs M205 and M207 connected in series, which is then connected in parallel with a circuit formed by SiC MOSFETs M206 and M208 connected in series, and then connected in series with the high-frequency inductor L203, before being connected in parallel to the battery module. This method utilizes LLC series resonant soft-switching technology to avoid the sharp increase in switching losses caused by increasing the inverter frequency to ultra-high frequencies, greatly improving the energy efficiency of the energy storage converter.

[0021] Preferably, the SiC full-bridge primary module further includes capacitors C201 to C204 and resistors R201 to R204; capacitor C201 and resistor R201 are connected in series and then in parallel to SiC MOSFET M201; capacitor C202 and resistor R202 are connected in series and then in parallel to SiC MOSFET M202; capacitor C203 and resistor R203 are connected in series and then in parallel to SiC MOSFET M203; capacitor C204 and resistor R204 are connected in series and then in parallel to SiC MOSFET M204.

[0022] The SiC full-bridge secondary module also includes capacitors C205 to C208 and resistors R205 to R208; capacitor C205 and resistor R205 are connected in series and then in parallel to SiC MOSFET M205; capacitor C206 and resistor R206 are connected in series and then in parallel to SiC MOSFET M206; capacitor C207 and resistor R207 are connected in series and then in parallel to SiC MOSFET M207; capacitor C208 and resistor R208 are connected in series and then in parallel to SiC MOSFET M208.

[0023] Preferably, the sampling feedback module includes a current sampling circuit and a voltage sampling circuit;

[0024] The current sampling circuit includes a Hall current sensor, an integrated differential amplifier circuit consisting of differential amplifier one and peripheral circuits of differential amplifier one, a low-pass filter circuit consisting of operational amplifier one and peripheral circuits of operational amplifier one, and an absolute value circuit consisting of operational amplifier two and peripheral circuits of operational amplifier two.

[0025] The voltage sampling circuit includes a Hall voltage sensor, an integrated differential amplifier circuit II composed of differential amplifier II and its peripheral circuits, and an absolute value circuit II composed of operational amplifier III and its peripheral circuits.

[0026] Preferably, the ultra-high frequency switch drive module includes a PWM signal isolation amplifier circuit and an ultra-high frequency switch drive circuit;

[0027] The PWM signal isolation amplifier circuit includes an optocoupler isolation circuit consisting of a high-speed optocoupler.

[0028] The ultra-high frequency switching drive circuit includes a power supply circuit consisting of a DC-DC power supply and peripheral circuits, a magnetically isolated gate drive integrated circuit consisting of an isolated drive chip and peripheral circuits, and a gate drive protection circuit.

[0029] Preferably, the integrated protection module includes an overcurrent detection protection circuit and an undervoltage and overvoltage protection circuit; the overcurrent detection protection circuit includes a dual voltage comparator and an optocoupler isolation circuit composed of a high-speed optocoupler; the undervoltage and overvoltage protection circuit includes two dual voltage comparators and a resistor divider circuit.

[0030] Preferably, the system communication module includes a CAN isolation communication circuit and an RS485 isolation communication circuit; the CAN isolation communication circuit includes an optocoupler isolation circuit three composed of a high-speed optocoupler three and a CAN signal generation circuit composed of a CAN transceiver; the RS485 isolation communication circuit includes an optocoupler isolation circuit four composed of a high-speed optocoupler four and an RS485 signal generation circuit composed of a 485 converter.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. This invention not only possesses excellent control precision and instantaneous response capabilities, but also effectively handles complex operating conditions, ensuring stable system operation. Supported by this digital control system, ultra-high frequency inverter technology can significantly improve the dynamic characteristics of the energy storage converter power hardware platform, fully leveraging the advantages of SiC power device-based energy storage converters;

[0033] 2. This invention is applicable to energy storage converters that use SiC devices as the main power devices. It integrates advanced drive control technology, which can effectively prevent damage to SiC power devices, suppress problems such as excessive transient voltage and current and electromagnetic interference during the driving process of SiC power devices, prevent voltage spikes from causing false triggering, and accurately manage the switching action of SiC devices.

[0034] 3. This invention has superior equipment protection capabilities. It integrates multiple advanced fault detection and protection circuits, which can comprehensively monitor key faults that may occur in each working stage of the energy storage converter. After a fault is detected, the MCU control system will shut down the primary and secondary inverter drive circuits to prevent the fault from spreading further. The stability and durability of the energy storage converter are improved through comprehensive protection strategies.

[0035] 4. This invention adopts high-speed, high-precision, fully digital control technology, which has higher control accuracy and faster response speed, realizes closed-loop control, and makes it easier to achieve refined design and control of energy storage converter, thereby improving power quality and power conversion efficiency. Attached Figure Description

[0036] Figure 1 This is the overall system block diagram of the digital control system for energy storage converter based on SiC power devices of the present invention;

[0037] Figure 2 This is a schematic diagram of the energy storage converter in the digital control system of the energy storage converter based on SiC power devices of this invention.

[0038] Figure 3 This is a schematic diagram of the PWM signal isolation amplifier circuit of the digital control system for energy storage converter based on SiC power devices according to the present invention.

[0039] Figure 4 This is a schematic diagram of the ultra-high frequency switching drive circuit of SiC power device in the digital control system of energy storage converter based on SiC power device of the present invention.

[0040] Figure 5 This is a schematic diagram of the current sampling circuit of the digital control system for energy storage converter based on SiC power devices according to the present invention.

[0041] Figure 6 This is a schematic diagram of the voltage sampling circuit of the digital control system for the energy storage converter based on SiC power devices according to the present invention.

[0042] Figure 7 This is a schematic diagram of the overcurrent detection and protection circuit of the digital control system for the energy storage converter based on SiC power devices according to the present invention.

[0043] Figure 8 This is a schematic diagram of the undervoltage and overvoltage protection circuit of the digital control system for the energy storage converter based on SiC power devices according to the present invention.

[0044] Figure 9 This is a schematic diagram of the RS485 isolated communication circuit of the digital control system for the energy storage converter based on SiC power devices of this invention.

[0045] Figure 10 This is a schematic diagram of the CAN isolated communication circuit of the digital control system for energy storage converter based on SiC power devices according to the present invention. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] This embodiment presents a digital control system for an energy storage converter based on SiC power devices, and its overall block diagram design is as follows: Figure 1 As shown, it includes an energy storage converter, an MCU control system, and control circuitry.

[0049] The control circuit includes an ultra-high frequency switch drive module, a sampling feedback module, a comprehensive protection module for protection in case of faults, and a system communication module for communication with the EMS system and the BMS system.

[0050] like Figure 2 As shown, the energy storage converter refers to an energy storage converter based on SiC power devices. The energy storage converter includes a DC / AC main circuit for converting current between DC and AC, two or more DC / DC main circuits for transforming and isolating DC power, and a battery pack module. In this embodiment, there are two DC / DC main circuits; in practical applications, there can be three, four, five, or even more.

[0051] The DC / AC main circuit includes a filter module, an inductor energy storage module, an inverter rectifier module, a filter and voltage regulator module, and a DC bus connected in sequence. Specifically, in the DC / AC main circuit, the filter module includes inductors L104 to L106 and capacitors C101 to C103; the inductor energy storage module includes inductors L101 to L103. The inverter rectifier module adopts a three-phase full-bridge rectifier topology formed by SiC IGBTs; the inverter rectifier module includes SiC IGBTs M101 to M106 and diodes D101 to D106; the filter and voltage regulator module includes filter and voltage regulator capacitors C104 to C107.

[0052] Each DC / DC main circuit includes a SiC full-bridge primary module, a high-frequency transformer T201, and a SiC full-bridge secondary module connected in sequence; the SiC full-bridge primary module is connected to the DC / AC main circuit through a DC bus; the SiC full-bridge primary module and the SiC full-bridge secondary module adopt a full-bridge topology formed by SiC MOSFETs.

[0053] Specifically, the SiC full-bridge primary module includes SiC MOSFETs M201 to M204; the SiC full-bridge primary module also includes capacitors C200, C201 to C204, and resistors R201 to R204.

[0054] The SiC MOSFETs M201 and M203 are connected in series, and together with the SiC MOSFETs M202 and M204 connected in series, they form a circuit that is connected in parallel to the DC / AC main circuit via the DC bus. The connection between SiC MOSFETs M201 and M203 is connected to the primary first input terminal of the high-frequency transformer T201 through capacitor C200. The connection between SiC MOSFETs M202 and M204 is connected to the primary second input terminal of the high-frequency transformer T201. Capacitor C201 and resistor R201 are connected in series and then in parallel to SiC MOSFET M201. Capacitor C202 and resistor R202 are connected in series and then in parallel to SiC MOSFET M202. Capacitor C203 and resistor R203 are connected in series and then in parallel to SiC MOSFET M203. Capacitor C204 and resistor R204 are connected in series and then in parallel to SiC MOSFET M204.

[0055] The SiC full-bridge secondary module includes SiC MOSFETs M205 to M208; the SiC full-bridge secondary module also includes capacitors C209, C205 to C208, and resistors R205 to R208.

[0056] The SiC MOSFETs M205 and M207 are connected in series, and together with the SiC MOSFETs M206 and M208 connected in series, they form a circuit that is connected in parallel to the battery module. The connection between SiC MOSFETs M205 and M207 is connected to the first output terminal of the secondary winding of the high-frequency transformer T201 through capacitor C209. The connection between SiC MOSFETs M206 and M208 is connected to the second output terminal of the secondary winding of the high-frequency transformer T201. Capacitor C205 and resistor R205 are connected in series and then in parallel to SiC MOSFET M205. Capacitor C206 and resistor R206 are connected in series and then in parallel to SiC MOSFET M206. Capacitor C207 and resistor R207 are connected in series and then in parallel to SiC MOSFET M207. Capacitor C208 and resistor R208 are connected in series and then in parallel to SiC MOSFET M208.

[0057] The three-phase AC grid and the battery module are bidirectionally connected through the connected DC / AC main circuit and DC / DC main circuit; the SiC power devices in the energy storage converter are rapidly turned on and off according to a preset timing sequence to realize the energy transfer from the three-phase AC grid to the battery module via power frequency AC-DC-high frequency AC-DC, or from the battery module to the three-phase AC grid via DC-high frequency AC-DC-power frequency AC.

[0058] When energy is transferred from the three-phase AC grid to the battery module, the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the input side, and the battery module is the output side. The SiC full-bridge primary module forms an inverter circuit, and the SiC full-bridge secondary module forms a rectifier circuit. When energy is transferred from the battery module to the three-phase AC grid, the battery module is the input side, and the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the output side. The SiC full-bridge secondary module forms an inverter circuit, and the SiC full-bridge primary module forms a rectifier circuit.

[0059] For the inverter circuit, the ultra-high frequency switching drive module outputs two complementary PWM signals with dead time to control the two diagonally opposite SiC MOSFETs of the inverter circuit to simultaneously turn on or off at high frequency, converting DC power into high frequency AC power.

[0060] For the rectifier circuit, the ultra-high frequency switching drive module turns off all SiC MOSFETs; the high-frequency AC power is rectified by the rectifier circuit composed of the body diodes of the SiC MOSFETs.

[0061] The MCU control system adjusts the output control signal using a PID algorithm based on the acquired current and voltage values. It then controls the operating states of the SiC full-bridge primary and secondary modules via an ultra-high frequency switch drive module. Specifically, based on the acquired measured current and voltage values ​​from the output side, it performs difference calculations with preset current and voltage setpoints. The average difference from these calculations is then used in a PID operation to obtain the current and voltage fluctuation values. Based on these fluctuations, the on and off times of the SiC MOSFETs in the inverter circuit are adjusted to regulate the duty cycle, ensuring that the output current and voltage values ​​closely approximate the preset current and voltage values.

[0062] This invention's control circuit uses an MCU control system as its core, combined with peripheral circuits to achieve functions such as process task control of the energy storage converter, hardware circuit switching control and electrical signal feedback regulation, equipment protection, and human-machine communication. The early PWM signal output from the MCU control system enters the ultra-high frequency switching drive circuit through a signal isolation amplification circuit, ultimately outputting a PWM signal to drive the SiC power devices, realizing the drive control of the SiC power devices in the DC / AC main circuit and DC / DC main circuit of the energy storage converter, and regulating the output characteristics of the energy storage converter. The sampling feedback module mainly includes current and voltage sampling circuits. The sampled feedback electrical signals are input to the ADC module for digital filtering and PID control processing. The comprehensive protection module includes overcurrent detection protection circuits and undervoltage and overvoltage protection circuits. When overcurrent faults, grid over / undervoltage, three-phase phase loss, etc., occur, the fault signal is sent to the GPIO pin of the MCU control system. The control system exits the workflow program through a GPIO interrupt, stops the PWM output, shuts down the primary and secondary inverter drive circuits, and sends the fault signal to the digital interactive interface, indicating the fault and displaying the fault type. The system communication module is mainly used for communication between the energy storage converter and the EMS and BMS systems. It consists of CAN and RS485 isolated communication circuits. The digital interactive interface is used to adjust the converter parameters and display the output current, voltage and charging / discharging status in real time.

[0063] The ultra-high frequency switching driver module includes a PWM signal isolation amplifier circuit and an ultra-high frequency switching driver circuit. For example... Figure 3 As shown, the PWM signal isolation amplifier circuit includes an optocoupler isolation circuit composed of a high-speed optocoupler. The task of the PWM signal isolation amplifier circuit is to improve the load capacity of the PWM signal and isolate it from the driver circuit board. Since the GPIO output load capacity of the MCU chip is limited, to reduce the MCU chip's output current and prevent external current from entering, the GPIO pins of the MCU chip are directly connected to the battery pack charge / discharge switching circuit. The battery pack charge / discharge switching circuit controls the battery pack module's entry and exit. When the battery pack module reaches 100% charge, a signal is sent to the relay via GPIO to exit the battery pack module circuit, preventing overcharging. Simultaneously, it waits for a discharge signal, and when discharge begins, it re-enters the battery pack module circuit. The subsequent stage uses a high-speed optocoupler for isolated output to prevent electromagnetic interference from the gate drive circuit from coupling to the digital control circuit. This protects the power control system, improves the system's anti-interference capability, and ensures the reliability and stability of the power supply operation.

[0064] like Figure 4As shown, the ultra-high frequency switching drive circuit includes a power supply circuit consisting of a DC-DC power supply and its peripheral circuitry, a magnetically isolated gate drive integrated circuit consisting of an isolated drive chip and its peripheral circuitry, and a gate drive protection circuit. In the power supply circuit, the secondary side voltage is provided by an integrated DC / DC converter isolated from the primary side power supply, which drives the PWM signal. The PWM signal output from the MCU chip is amplified, magnetically isolated, and then output to the Miller clamp circuit and short-circuit protection circuit via the PWM output circuit, finally outputting to the SiC power device. In the Miller clamp circuit, the CLAMP pin inputs the gate voltage of the SiC power device to the logic clamp circuit after logic comparison and discharges crosstalk charge. In the short-circuit protection circuit, the drain of the SiC power device is connected to the desaturation detection circuit through a fast recovery diode D2 to detect the drain voltage. During overcurrent, the logic circuit outputs a negative gate voltage to softly turn off the SiC power device to prevent damage. Additionally, the fault signal in the PWM output circuit can be pulled up and output to the MCU chip for software monitoring, and the Reset pin level can be controlled to reset and exit the protection state.

[0065] The sampling feedback module collects the current and voltage values ​​of the battery pack module, as well as the current and voltage values ​​of the DC bus between the SiC full-bridge primary module and the DC / AC main circuit, and sends the collected current and voltage values ​​to the MCU control system. The sampling feedback module includes a current sampling circuit and a voltage sampling circuit.

[0066] like Figure 5 As shown, the current sampling circuit includes a Hall current sensor, an integrated differential amplifier circuit consisting of differential amplifier one and its peripheral circuits, a low-pass filter circuit consisting of operational amplifier one and its peripheral circuits, and an absolute value circuit consisting of operational amplifier two and its peripheral circuits.

[0067] The current sampling circuit uses a Hall current sensor, which converts the sensed current value into a low-amplitude voltage through the Hall effect and outputs it. The output voltage is processed by the sampling feedback circuit: the signal is divided by R501 and R505 and then transmitted to an integrated differential amplifier circuit with a high common-mode rejection ratio to improve the load capacity of the subsequent stage and reduce the effects of temperature drift and power supply common-mode interference. The subsequent stage is designed with a unity-gain KRC low-pass filter circuit, which has an attenuation slope of -40dB and has a good filtering effect. Due to the bidirectional energy transfer, in order to prevent negative voltage from affecting the operation of the ADC, an absolute value circuit is designed at the output to ensure that the feedback signal received by the ADC is between 0-3.3V, thus ensuring the validity of the signal. Finally, it is input to the ADC pin of the MCU chip after passing through a Zener diode and a filter capacitor.

[0068] like Figure 6As shown, the voltage sampling circuit includes a Hall voltage sensor, an integrated differential amplifier circuit II composed of differential amplifier II and its peripheral circuits, a second-order low-pass filter circuit, and an absolute value circuit II composed of operational amplifier III and its peripheral circuits.

[0069] For voltage sampling of the DC bus and battery pack of the energy storage converter, the Hall voltage sensor senses the power supply output voltage as a low-amplitude current for output. The input current is converted into a low-amplitude voltage output through the precision resistor R601 in the kiloohm range. Similar to the current feedback sampling circuit, the signal needs to pass through the integrated differential amplifier circuit II, the second-order low-pass filter circuit, and the absolute value circuit II before entering the ADC pin of the MCU.

[0070] The integrated protection module includes overcurrent detection and protection circuits and undervoltage and overvoltage protection circuits. For example... Figure 7 As shown, the overcurrent detection and protection circuit includes a dual voltage comparator and an optocoupler isolation circuit consisting of a high-speed optocoupler. The sampling mutual inductance coil converts the power supply output current through a corresponding conversion ratio and connects it to the P1 interface. After rectification, it is converted into a DC voltage signal by R701 and input to the inverting terminal of the dual voltage comparator. The non-inverting terminal of the inverter is connected to the reference voltage. V ref This circuit can be adjusted V ref Change the overcurrent detection and protection circuit's overcurrent judgment threshold. When the current exceeds the set protection threshold, the comparator outputs a low level, which in turn turns on optocoupler U703 and optocoupler U704, interlocking with U703. Subsequently, the high-speed optocoupler turns on, outputting a high level, the fault indicator light illuminates, and a signal is input to the MCU chip's GPIO, stopping the system operation via an interrupt.

[0071] like Figure 8 As shown, the undervoltage and overvoltage protection circuit includes two dual-voltage comparators and a resistor divider circuit. The 15V DC control power generated by the power supply module of the power control system is divided and input to different comparator inputs, along with the corresponding set reference voltage. V ref By comparison, when the mains voltage fluctuation exceeds the set protection threshold (±10%), a fault signal is generated to the MCU chip to prevent the power supply from outputting power under unstable voltage conditions.

[0072] The system communication module includes a CAN isolated communication circuit and an RS485 isolated communication circuit. For example... Figure 9As shown, the RS485 isolated communication circuit includes an optocoupler isolation circuit consisting of four high-speed optocouplers and an RS485 signal generation circuit consisting of a 485 converter. The RS485 isolated communication circuit converts the TTL level output by the MCU chip into a differential signal that can be transmitted on the 485 bus (or performs an inverse conversion). The RE, DE, and RE / DE pins of the MCU chip are connected to the 485 converter after being isolated by high-speed optocouplers. After the TTL level signal is converted into a differential signal, it is transmitted to the 485 bus through a terminating resistor and a filtering capacitor. D1 is a TVS diode module, which can be used to suppress surge impacts on the 485 bus and protect the circuit and the chip.

[0073] like Figure 10 As shown, the CAN isolation communication circuit includes an optocoupler isolation circuit consisting of a high-speed optocoupler and a CAN signal generation circuit consisting of a CAN transceiver. The MCU chip transmits or receives TTL levels through relevant GPIO pin signals. The high-speed optocoupler isolates the MCU chip pins from the CAN transceiver. The CAN transceiver converts the TTL level emitted by the MCU chip into a differential signal transmitted by CANL and CANH, and then connects the node to the CAN bus to communicate with external devices.

[0074] Example 2

[0075] This embodiment provides a digital control system for an energy storage converter based on SiC power devices. The difference between this embodiment and the first embodiment is that in the DC / DC main circuit of the energy storage converter, the SiC full-bridge secondary module further includes inductors L201 and L202; the connection between SiC MOSFET M201 and SiC MOSFET M203 is connected to the first input terminal of the primary of the high-frequency transformer T201 through a series capacitor C200 and inductor L201; and inductor L202 is connected in parallel to the primary of the high-frequency transformer T201.

[0076] The SiC full-bridge secondary module also includes an inductor L203; the circuit formed by the series connection of SiC MOSFET M205 and SiC MOSFET M207, and the circuit formed by the series connection of SiC MOSFET M206 and SiC MOSFET M208, are connected in parallel, then connected in series with the high-frequency inductor L203, and finally connected in parallel to the battery module.

[0077] This embodiment utilizes LLC series resonant soft-switching technology to avoid the sharp increase in switching losses caused by increasing the inverter frequency to ultra-high frequency, thus greatly improving the energy efficiency of the energy storage converter.

[0078] The rest of the structure in this embodiment is the same as in Embodiment 1.

[0079] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A digital control system for an energy storage converter based on SiC power devices, characterized in that: This includes energy storage converters, MCU control systems, and control circuits; The control circuit includes an ultra-high frequency switch drive module, a sampling feedback module, a comprehensive protection module for protection in case of fault, and a system communication module for communication with the EMS system and the BMS system. The energy storage converter refers to an energy storage converter based on SiC power devices; the energy storage converter includes a DC / AC main circuit for converting current between DC and AC, two or more DC / DC main circuits for transforming and isolating DC power, and a battery pack module; the DC / AC main circuits are connected to the DC / DC main circuits through a DC bus; each DC / DC main circuit is connected to the battery pack module. The sampling feedback module collects the current and voltage values ​​of the battery pack module and the current and voltage values ​​of the DC bus between the DC / DC main circuit and the DC / AC main circuit, and sends the collected current and voltage values ​​to the MCU control system. The MCU control system adjusts the output control signal using a PID algorithm based on the collected current and voltage values, and controls the working state of the SiC power devices in the energy storage converter through the ultra-high frequency switching drive module. Each DC / DC main circuit includes a SiC full-bridge primary module, a high-frequency transformer T201, and a SiC full-bridge secondary module connected in sequence; the SiC full-bridge primary module is connected to the DC / AC main circuit via a DC bus; the SiC full-bridge primary module and the SiC full-bridge secondary module adopt a full-bridge topology formed by SiC MOSFETs. The three-phase AC power grid and the battery module achieve bidirectional energy transfer through the connected DC / AC main circuit and DC / DC main circuit. When energy is transferred from the three-phase AC grid to the battery module, the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the input side, and the battery module is the output side. The SiC full-bridge primary module forms an inverter circuit, and the SiC full-bridge secondary module forms a rectifier circuit. When energy is transferred from the battery module to the three-phase AC grid, the battery module is the input side, and the DC bus between the SiC full-bridge primary module and the DC / AC main circuit is the output side. The SiC full-bridge secondary module forms an inverter circuit, and the SiC full-bridge primary module forms a rectifier circuit. For the inverter circuit, the ultra-high frequency switching drive module outputs two complementary PWM signals with dead time to control the two diagonally opposite SiC MOSFETs of the inverter circuit to simultaneously turn on or off at high frequency, converting DC power into high frequency AC power. For the rectifier circuit, the ultra-high frequency switching drive module turns off all SiC MOSFETs; the high-frequency AC power is rectified by the rectifier circuit composed of the body diodes of the SiC MOSFETs. The SiC full-bridge primary module includes SiC MOSFETs M201 to M204; the SiC full-bridge primary module also includes capacitor C200. The SiC MOSFET M201 and SiC MOSFET M203 are connected in series, and together with the SiC MOSFET M202 and SiC MOSFET M204 connected in series, they form a circuit that is connected in parallel to the DC / AC main circuit via the DC bus. The connection between SiC MOSFET M201 and SiC MOSFET M203 is connected to the primary first input terminal of the high-frequency transformer T201 through capacitor C200. The connection between SiC MOSFET M202 and SiC MOSFET M204 is connected to the primary second input terminal of the high-frequency transformer T201. The SiC full-bridge secondary module includes SiC MOSFETs M205 to M208; the SiC full-bridge secondary module also includes capacitor C209. The SiC MOSFET M205 and SiC MOSFET M207 are connected in series, and together with the circuit formed by the SiC MOSFET M206 and SiC MOSFET M208 connected in series, they are connected in parallel to the battery module. The connection between SiC MOSFET M205 and SiC MOSFET M207 is connected to the first output terminal of the secondary winding of the high-frequency transformer T201 through capacitor C209. The connection between SiC MOSFET M206 and SiC MOSFET M208 is connected to the second output terminal of the secondary winding of the high-frequency transformer T201.

2. The digital control system for energy storage converter based on SiC power devices according to claim 1, characterized in that: The MCU control system adjusts the output control signal using a PID algorithm based on the collected current and voltage values. This means that the control signal is adjusted based on the measured current and voltage values ​​collected from the output side. The difference between the current and voltage settings on the output side is calculated, and the average difference is used for several calculations to obtain the current fluctuation value and voltage fluctuation value. Based on the current fluctuation value and voltage fluctuation value, the turn-on and turn-off time of the SiC MOSFET in the inverter circuit is changed to achieve duty cycle adjustment so that the current and voltage values ​​on the output side are close to the current and voltage settings respectively.

3. The digital control system for energy storage converter based on SiC power devices according to claim 1, characterized in that: The SiC full-bridge secondary module also includes inductors L201 and L202; the connection between SiC MOSFET M201 and SiC MOSFET M203 is connected to the first input terminal of the primary of high-frequency transformer T201 through a series capacitor C200 and inductor L201; inductor L202 is connected in parallel to the primary of high-frequency transformer T201. The SiC full-bridge secondary module also includes an inductor L203; the circuit formed by the series connection of SiC MOSFET M205 and SiC MOSFET M207, and the circuit formed by the series connection of SiC MOSFET M206 and SiC MOSFET M208, are connected in parallel, then connected in series with the high-frequency inductor L203, and then connected in parallel to the battery pack module.

4. The digital control system for energy storage converter based on SiC power devices according to claim 1, characterized in that: The SiC full-bridge primary module also includes capacitors C201 to C204 and resistors R201 to R204; capacitor C201 and resistor R201 are connected in series and then in parallel to SiC MOSFET M201; capacitor C202 and resistor R202 are connected in series and then in parallel to SiC MOSFET M202; capacitor C203 and resistor R203 are connected in series and then in parallel to SiC MOSFET M203; capacitor C204 and resistor R204 are connected in series and then in parallel to SiC MOSFET M204. The SiC full-bridge secondary module also includes capacitors C205 to C208 and resistors R205 to R208; capacitor C205 and resistor R205 are connected in series and then in parallel to SiC MOSFET M205; capacitor C206 and resistor R206 are connected in series and then in parallel to SiC MOSFET M206; capacitor C207 and resistor R207 are connected in series and then in parallel to SiC MOSFET M207; capacitor C208 and resistor R208 are connected in series and then in parallel to SiC MOSFET M208.

5. The digital control system for energy storage converter based on SiC power devices according to any one of claims 1 to 4, characterized in that: The sampling feedback module includes a current sampling circuit and a voltage sampling circuit; The current sampling circuit includes a Hall current sensor, an integrated differential amplifier circuit consisting of differential amplifier one and peripheral circuits of differential amplifier one, a low-pass filter circuit consisting of operational amplifier one and peripheral circuits of operational amplifier one, and an absolute value circuit consisting of operational amplifier two and peripheral circuits of operational amplifier two. The voltage sampling circuit includes a Hall voltage sensor, an integrated differential amplifier circuit II composed of differential amplifier II and its peripheral circuits, and an absolute value circuit II composed of operational amplifier III and its peripheral circuits.

6. The digital control system for energy storage converter based on SiC power devices according to any one of claims 1 to 4, characterized in that: The ultra-high frequency switching drive module includes a PWM signal isolation amplifier circuit and an ultra-high frequency switching drive circuit. The PWM signal isolation amplifier circuit includes an optocoupler isolation circuit consisting of a high-speed optocoupler. The ultra-high frequency switching drive circuit includes a power supply circuit consisting of a DC-DC power supply and peripheral circuits, a magnetically isolated gate drive integrated circuit consisting of an isolated drive chip and peripheral circuits, and a gate drive protection circuit.

7. The digital control system for energy storage converter based on SiC power devices according to any one of claims 1 to 4, characterized in that: The integrated protection module includes an overcurrent detection protection circuit and an undervoltage and overvoltage protection circuit; the overcurrent detection protection circuit includes a dual voltage comparator and an optocoupler isolation circuit composed of a high-speed optocoupler; the undervoltage and overvoltage protection circuit includes two dual voltage comparators and a resistor divider circuit.

8. The digital control system for energy storage converter based on SiC power devices according to any one of claims 1 to 4, characterized in that: The system communication module includes a CAN isolation communication circuit and an RS485 isolation communication circuit; the CAN isolation communication circuit includes an optical coupler isolation circuit three composed of a high-speed optical coupler three and a CAN signal generation circuit composed of a CAN transceiver; the RS485 isolation communication circuit includes an optical coupler isolation circuit four composed of a high-speed optical coupler four and an RS485 signal generation circuit composed of a 485 converter.

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