MMC type mining battery energy storage system power electronic conversion device

Abstract

The present invention belongs to the technical field of power electronic converters, and provides a power electronic converter device for an MMC type mining battery energy storage system, including three phase units connected in parallel, a main control board and a plurality of slave control boards, each phase unit including an upper bridge arm, an upper bridge arm inductor, a lower bridge arm inductor and a lower bridge arm connected in series in sequence. The upper bridge arm and the lower bridge arm both include a plurality of energy storage submodules connected in series in sequence, the number of energy storage submodules in the upper bridge arm is equal to the number of energy storage submodules in the lower bridge arm, and the energy storage submodule is formed by a half-bridge circuit and an energy storage battery connected in parallel. Based on the master-slave control-like digital control mode of the main control board and the slave control board, the reliability of the transmission of the sampling signal and the drive signal is guaranteed, and the interference of each power unit is reduced. At the same time, the purpose of isolating the system in high-voltage and high-power application occasions and preventing electromagnetic interference is also met, and the signal transmission between the upper control algorithm and the submodule control system is realized, and the requirements of high-speed complex calculation and high-precision control are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronic converters, and in particular relates to a power electronic converter device for an MMC type mining battery energy storage system. Background Art

[0002] Electricity is the primary energy source for coal mine production. Mine hoisting, transportation, ventilation, drainage, compressed air, gas extraction, and mining operations all rely on electricity. The power supply system plays an increasingly crucial role in coal mine safety. The National Electricity Regulatory Commission's "Opinions on Strengthening the Supervision and Management of Power Supply and Self-Provided Emergency Power Supply Configuration for Important Power Users" stipulates that exceptionally important power users must have three power sources. Important power users of exceptional, first-, and second-level grades must also have their own emergency power supply, ensuring that the capacity reaches 120% of the safety load and ensuring safe operation. Article 436 of the "Coal Mine Safety Regulations" stipulates that mines must have two power supply circuits. If one circuit fails and stops supplying power, the other circuit must carry the entire mine's electrical load. However, due to objective geographical factors, mines located in minefields or subject to thunderstorms are susceptible to mine or local power outages caused by lightning strikes during thunderstorms. Therefore, emergency power supplies, as a third power source, have become an essential option for coal mine emergency rescue. Battery energy storage systems are highly suitable for coal mine emergency power supply systems due to their high reliability, rapid startup, and flexible functional configuration. Thanks to the rapid development of power electronics technology and the continuous application of new devices and theories, the power conversion systems in battery energy storage systems have the potential to perform a variety of high-value-added functions in non-emergency situations, such as reactive power compensation, power factor correction, and profiting from peak-valley electricity price differences. Therefore, the research results of the power electronic conversion device of the MMC type mine battery energy storage system are of great significance and promotional application value for improving the safety and reliability of coal mine power supply. They can also be promoted and applied to important power users such as special, primary, and secondary power users, and have great economic and social significance. Summary of the Invention

[0003] The present invention is made to solve the above problems and aims to provide a power electronic conversion device for an MMC type mining battery energy storage system.

[0004] The present invention provides an MMC type mining battery energy storage system power electronic conversion device, which has the following characteristics: three phase units connected in parallel, a main control board and multiple slave control boards, each phase unit includes an upper bridge arm, an upper bridge arm inductor, a lower bridge arm inductor and a lower bridge arm connected in series in sequence, the upper bridge arm and the lower bridge arm each include multiple energy storage submodules connected in series in sequence, the number of energy storage submodules in the upper bridge arm is equal to the number of energy storage submodules in the lower bridge arm, the energy storage submodule is formed by a half-bridge circuit and an energy storage battery connected in parallel, the upper bridge arm has an upper bridge arm positive terminal and an upper bridge arm negative terminal, the upper bridge arm positive terminal is the positive terminal of the first energy storage submodule in the upper bridge arm, the upper bridge arm negative terminal is the negative terminal of the last energy storage submodule in the upper bridge arm, and the lower bridge arm has a lower bridge arm. The positive terminal and the negative terminal of the lower bridge arm, the positive terminal of the lower bridge arm is the positive terminal of the first energy storage sub-module in the lower bridge arm, the negative terminal of the lower bridge arm is the negative terminal of the last energy storage sub-module in the lower bridge arm, one end of the upper bridge arm inductor is connected to the negative terminal of the upper bridge arm, and the other end is connected to one end of the lower bridge arm inductor, and the other end of the lower bridge arm inductor is connected to the positive terminal of the lower bridge arm. The number of slave control boards is equal to the number of energy storage sub-modules. One energy storage sub-module is connected to one slave control board. The slave control board is used to collect data from the corresponding energy storage sub-module. The main control board is connected to multiple slave control boards respectively, for receiving data from the slave control boards and generating switch control signals according to the data and sending the switch control signals to the corresponding slave control boards to control the working state of the corresponding energy storage sub-modules.

[0005] In the MMC type mining battery energy storage system power electronic conversion device provided by the present invention, it can also have the following characteristics: wherein, the main control board includes a main FPGA chip and a DSP connected to the main FPGA chip through XINTF, and the main FPGA chip and DSP cooperate with each other to generate a switch control signal to control the working state of the corresponding energy storage sub-module.

[0006] In the MMC type mining battery energy storage system power electronic conversion device provided by the present invention, it can also have the following characteristics: wherein the half-bridge circuit includes a first controllable power switch tube T1, a second controllable power switch tube T2, a first anti-parallel diode D1, a second anti-parallel diode D2 and an energy storage capacitor C SM The first controllable power switch tube T1 and the second controllable power switch tube T2 are connected in series, the emitter of the first controllable power switch tube T1 is connected to the collector of the second controllable power switch tube T2, and is connected to the cathode of the first anti-parallel diode D1, the collector of the first controllable power switch tube T1 is connected to the anode of the first anti-parallel diode D1 and the energy storage capacitor C SM The collector of the second controllable power switch tube T2 is connected to the positive electrode of the second anti-parallel diode D2, the emitter of the second controllable power switch tube T2 is connected to the negative electrode of the second anti-parallel diode D2, and is connected to the energy storage capacitor CSM The negative pole is connected.

[0007] In the MMC type mining battery energy storage system power electronic conversion device provided by the present invention, it can also have the following characteristics: wherein, the slave control board includes a slave FPGA chip, an optical fiber transmitting and receiving circuit, a voltage and current detection circuit, a temperature detection circuit, an AD conversion circuit, an IGBT drive and fault return circuit and an IO drive circuit.

[0008] In the MMC type mining battery energy storage system power electronic conversion device provided by the present invention, it can also have the following features: wherein, the slave FPGA chip is connected to the main control board, the second controllable power switch tube and the temperature detection circuit, the optical fiber transmitting and receiving circuit is used to receive data sent by the main control board and send data detected and converted by the slave control board, the voltage and current detection circuit is used to collect the voltage and current of the energy storage submodule during operation, the temperature detection circuit is used to collect the temperature of the first controllable power switch tube T1 and the second controllable power switch tube T2, the AD conversion circuit is used to collect the capacitor voltage of the energy storage submodule, and the IGBT drive and fault return circuit is used to drive the first controllable power switch tube T1 and the second controllable power switch tube T2 to be turned on and off and receive fault signals of the first controllable power switch tube T1 and the second controllable power switch tube T2.

[0009] In the MMC type mining battery energy storage system power electronic conversion device provided by the present invention, it can also have the following characteristics: wherein, the main control board and the slave control board are connected through two optical fibers for exchanging data, one optical fiber controls the sending of data, and the other optical fiber controls the receiving of data.

[0010] Functions and effects of the invention

[0011] The present invention provides an MMC type mine battery energy storage system power electronic conversion device with high reliability, easy to realize multi-level number and modular design, which is mainly suitable for application in coal mine emergency power supply systems. The main circuit topology is a modular multi-level converter with sub-modules integrated with energy storage batteries, which can effectively store or output high-quality low-harmonic electric energy and perform reliable functions such as reactive power compensation and power factor correction. Based on the master-slave control-like digital control mode of the main control board and the slave control board, the use of optical fiber communication can ensure the reliability of the transmission of sampling signals and drive signals, and reduce the interference of each power unit. At the same time, it also meets the purpose of isolation and prevention of electromagnetic interference of high-voltage and high-power application systems, realizes the upper-level control algorithm (MMC system control algorithm) and the signal transmission (sampling information and pulse drive signal) with the sub-module control system, and realizes high-speed complex calculations and high-precision control requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1is a schematic diagram of the overall control architecture of the device system in an embodiment of the present invention;

[0013] Figure 2 1 is a topological diagram of a power conversion circuit of a three-phase MMC energy storage converter in an embodiment of the present invention;

[0014] Figure 3 is a diagram of the working mode of the submodules in the bridge arm in an embodiment of the present invention;

[0015] Figure 4 is a schematic diagram of the control connection principle between a single slave control board and a single submodule in an embodiment of the present invention; and

[0016] Figure 5 It is a schematic diagram of the control structure of a single submodule by the device system in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the following is a detailed description of an MMC type mining battery energy storage system power electronic conversion device (hereinafter referred to as the device) of the present invention in conjunction with the embodiments and drawings.

[0018] <Example>

[0019] In this embodiment, the number of slave control boards and energy storage submodules is described as 24. In actual applications, the number of slave control boards and energy storage submodules may be hundreds. The controllable power switch tube can be an IGBT or a MOSFET. In this embodiment, an IGBT is used.

[0020] Figure 1 is a schematic diagram of the overall control architecture of the device system in an embodiment of the present invention; Figure 2 4 is a topological diagram of a power conversion circuit of a three-phase MMC energy storage converter in an embodiment of the present invention.

[0021] like Figure 1 、 2 As shown in the figure, the MMC mining battery energy storage system power electronic conversion device includes three phase units (phase a, phase b, and phase c) connected in parallel, a master control board, and 24 slave control boards. The 24 slave control boards include 8 slave control boards for phase a, 8 slave control boards for phase b, and 8 slave control boards for phase c.

[0022] Each phase unit j (j = a, b, c) includes an upper bridge arm, an upper bridge arm inductor L0, a lower bridge arm inductor L0 connected in series ’ and the lower bridge arm.

[0023] Both the upper bridge arm and the lower bridge arm include a plurality of energy storage submodules connected in series. The number of the energy storage submodules in the upper bridge arm is equal to the number of the energy storage submodules in the lower bridge arm, both being 4.

[0024] The upper bridge arm has an upper bridge arm positive terminal and an upper bridge arm negative terminal. The upper bridge arm positive terminal is the positive terminal of the first energy storage submodule in the upper bridge arm, and the upper bridge arm negative terminal is the negative terminal of the last energy storage submodule in the upper bridge arm. The lower bridge arm has a lower bridge arm positive terminal and a lower bridge arm negative terminal. The lower bridge arm positive terminal is the positive terminal of the first energy storage submodule in the lower bridge arm, and the lower bridge arm negative terminal is the negative terminal of the last energy storage submodule in the lower bridge arm. One end of the upper bridge arm inductor L0 is connected to the upper bridge arm negative terminal, and the other end is connected to the lower bridge arm inductor L0. ’ One end of the lower bridge arm inductor L0 is connected to ’ The other end is connected to the positive terminal of the lower bridge arm. The positive terminal of the upper bridge arm serves as the positive terminal of the DC output line of the phase unit, and the negative terminal of the lower bridge arm serves as the negative terminal of the DC output line of the phase unit.

[0025] The energy storage submodule consists of a half-bridge circuit and an energy storage battery U bat The half-bridge circuit includes a first controllable power switch tube T1, a second controllable power switch tube T2, a first anti-parallel diode D1, a second anti-parallel diode D2 and an energy storage capacitor C SM .

[0026] The first controllable power switch tube T1 and the second controllable power switch tube T2 are connected in series. The emitter of the first controllable power switch tube T1 is connected to the collector of the second controllable power switch tube T2 and is also connected to the cathode of the first anti-parallel diode D1. The collector of the first controllable power switch tube T1 is connected to the anode of the first anti-parallel diode D1 and the energy storage capacitor C. SM The collector of the second controllable power switch tube T2 is connected to the positive electrode of the second anti-parallel diode D2, the emitter of the second controllable power switch tube T2 is connected to the negative electrode of the second anti-parallel diode D2, and is connected to the energy storage capacitor C SM The negative pole is connected.

[0027] The number of slave control boards is equal to the number of energy storage sub-modules. One energy storage sub-module is connected to one slave control board, and the slave control board is used to collect data from the corresponding energy storage sub-module.

[0028] The main control board is connected to multiple slave control boards respectively, and is used to receive data from the slave control boards and generate switch control signals according to the data and send the switch control signals to the corresponding slave control boards to control the working status of the corresponding energy storage submodules.

[0029] The master control board and slave control boards exchange data via two optical fibers: one for data transmission and the other for data reception. The master control board is connected to a total of 48 optical fibers (2 x 8 x 3), ensuring reliable transmission of sampling and drive signals and reducing interference between power units. This also ensures system isolation and electromagnetic interference prevention in high-voltage, high-power applications.

[0030] Each slave control board and its corresponding energy storage submodule form a valve group level, and the four energy storage submodules in a bridge arm form a bridge arm level, that is, four valve group levels form a bridge arm level, and a total of six bridge arms in the system form a system level.

[0031] Each slave control board is responsible for collecting information such as voltage, current, and temperature during operation of each energy storage submodule. In this embodiment, there are 24 slave control boards. These boards exchange data with the master control board in real time via fiber-optic communication. Upon receiving instructions from the master control board, they drive each energy storage submodule. This master-slave architecture and the use of fiber-optic communication ensure reliable transmission of sampling and drive signals, reduce interference between power units, and achieve system isolation and electromagnetic interference prevention in high-voltage, high-power applications. Each slave control board corresponding to an energy storage submodule has a certain degree of autonomy for its own submodule. Simple operations, such as directly disconnecting a submodule when the slave control board detects abnormal temperature, voltage, and current information, bypass the processing of the upper-level controller (i.e., the master control board). This simple operation directly distributes and generates disconnect signals for the corresponding submodule. The corresponding switching control signals are then sent to the controllable power transistors (IGBTs) in each half-bridge circuit to turn them on and off, achieving valve group-level control. Information exchange between the four submodules in a single bridge arm (via four slave FPGAs) ensures consistent battery voltage within each submodule within the arm. A comprehensive system control algorithm is implemented through the coordinated control of the master DSP, master FPGA, and 24 slave FPGAs, achieving system-level control, such as in the event of a major system disturbance or imbalance. The hardware control system implements a fully digital three-level control system: valve group-level control primarily involves turning on and off the switches; arm-level control primarily handles energy balance within the arm; and system-level control primarily involves the computation and processing of the upper-level system control algorithm.

[0032] Figure 3 3 is a diagram of the working mode of the submodules in the bridge arm in an embodiment of the present invention.

[0033] like Figure 3 As shown in the figure, the working state of the energy storage submodule (SM) is determined by T1, T2 and the direction of the current in the phase bridge arm of the circuit. Figure 3These are the six operating modes of the submodule. When the upper switch T1 is in the open state and the lower switch T2 is in the closed state, the SM is in the on state, and its output is the battery voltage; when T1 is in the closed state and T2 is in the open state, the SM is in the cut-off state, and its output is zero (ignoring the turn-on voltage drop of the switching device); when both T1 and T2 are closed, the submodule is in the locked state, that is, an abnormal operating state. Specifically, the device can perform bidirectional energy storage charging and discharging management. In the charging mode, a single energy storage submodule rectifies the AC voltage into the DC voltage required by the energy storage battery. In the discharge mode, the DC power generated by the discharge of the energy storage battery is inverted into AC power through the cooperation of multiple submodules of the power conversion circuit. The output voltage of each phase of the half-bridge energy storage converter module is cascaded and superimposed to form a step waveform that is close to a sine wave.

[0034] Figure 4 It is a schematic diagram of the control connection principle between a single slave control board and a single sub-module in an embodiment of the present invention.

[0035] like Figure 4 As shown, each submodule is associated with a subcontroller, and the sampling circuit samples the information during the operation of the submodule, including the submodule energy storage battery voltage sampling circuit, the bridge arm current sampling circuit, and the device temperature sampling circuit. The sampled information is then converted from digital to analog and sent to the slave FPGA chip for processing. The slave FPGA chip can transmit the signal to the upper level through the optical fiber transmitter, or directly process simple information (for example, when the submodule temperature is abnormal, the submodule is directly removed), and send a PWM pulse signal to the drive circuit. The drive circuit conditions and amplifies the PWM pulse signal and converts it into a switching signal that meets the required driving capability, driving the controllable power switch tubes T1 and T2 to turn on and off, thereby realizing the activation or removal of the submodule.

[0036] The slave control board includes a slave FPGA chip, fiber optic transmission and reception circuits, voltage and current detection circuits, temperature detection circuits, A / D conversion circuits, IGBT drive and fault return circuits, and I / O drive circuits. The slave FPGA chip uses the ProASIC3A3P250 chip from Aite; the controllable switching device (IGBT) uses the FF650R17IE4 module from Infineon; the voltage sensor uses the AV100-2000 voltage sensor from LEM; the current sensor uses the LT508-S6 current sensor from LEM; the A / D conversion circuit uses the AD7656 chip from Analog Devices; and the IGBT drive circuit uses the 2SP0320V2A0 dual-channel IGBT driver board from CONCEPT.

[0037] The slave FPGA chip receives commands from the main control board via the optical fiber interface, as well as information collected from the temperature, voltage, and current sampling circuits on the control board. The optical fiber transmitting and receiving circuits receive data from the main control board and transmit data detected and converted by the slave control board. The voltage and current detection circuits collect the voltage and current of the energy storage submodule during operation. The temperature detection circuit collects the temperature of the IGBT. The A / D conversion circuit collects the capacitor voltage of the energy storage submodule. The IGBT drive circuit drives the IGBT on and off.

[0038] Figure 5 It is a schematic diagram of the control structure of a single submodule by the device system in an embodiment of the present invention.

[0039] like Figure 5 As shown, each slave control board is responsible for collecting voltage, current, and temperature information from each submodule during operation. This information is transmitted in real time to the master control board, the superior controller, via optical fiber communication. This information is then used by the system's upper-level complex algorithms. The master FPGA in the master control board receives voltage and current information from each slave control board via optical fiber transmission and reception circuits, and communicates with the master DSP via the XINTH interface. The master FPGA and DSP collaborate to implement the upper-level system control algorithm. The master control board assesses the system's operating status and issues appropriate command values, sending these signals to each slave control board via the optical fiber transmission circuit. After receiving the command via the optical fiber reception circuit, the slave control board sends a switching control signal to the controllable IGBT (IGBT) in each submodule, controlling the submodule's operating state (on or off) and ensuring normal system operation. This allows the master control board to coordinate and control the 24 slave control boards and the 24 submodules, effectively controlling the entire system. The master DSP also includes a human-computer interface, allowing the system's operating status to be set in real time via the host computer. The DSP chip in the main control board completes the system algorithm, exchanges data with the main FPGA chip, and communicates with the human-machine interface circuit; the main PFGA receives system operation information sent from the slave controller, the main FPGA exchanges data with the main DSP, and the main DSP compares the sampled information with the reference value given by the host computer, and performs top-level algorithm calculations based on the feedback deviation, mainly including output current tracking, internal system circulation suppression, and sub-module capacitor voltage balance control algorithm calculations. Then the main FPGA performs modulation and demodulation according to the control signal sent by the main DSP, calculates the duty cycle of the switching pulse, and transmits it to the slave controller through the optical fiber interface.

[0040] The main control board utilizes a master DSP chip with powerful computing capabilities and a master FPGA chip with abundant pin resources, leveraging their respective strengths to effectively meet the performance requirements of computing complex control algorithms and exchanging data with a large number of slave control boards. The DSP uses the Texas Instruments (TI) TMS320F28335 chip, which can output up to 12 PWM pulses. However, the TMS320F28335's PWM resources are clearly insufficient for MMCs with a large number of cascaded connections. The FPGA chip, on the other hand, boasts abundant I / O interface resources and allows for flexible configuration without hardware circuit changes, effectively compensating for the DSP's interface deficiencies. The present invention utilizes a master DSP + master FPGA as the control core to simultaneously meet the requirements of large-scale data computing and a rich I / O interface. The main FPGA chip uses the XC3S400-4PQG208C chip produced by Xilinx. The FPGA chip contains 400,000 logic gates, 141 I / O ports, and a core voltage of 1.14-1.26V. The chip has low power consumption, high working efficiency, can process multiple signals in parallel, and has strong anti-interference ability, which can effectively improve the working reliability of the power unit while meeting the real-time requirements of the system; the optical fiber transmission and receiving circuits respectively use the HFBR-1521Z transmitter and HFBR-2521Z receiver produced by Avago High-Tech Corporation; the human-machine interface circuit uses the RSM485PCHT transceiver produced by Zhiyuan Electronics Corporation.

[0041] Functions and Effects of the Embodiments

[0042] The MMC mining battery energy storage system power electronic converter provided in this embodiment features a three-phase main power conversion circuit. Each phase includes an upper and lower bridge arm, resulting in three phases and six bridge arms. Each bridge arm consists of a bridge arm inductor L0 connected in series with four submodules, employing a modular cascade structure. The submodules within each phase's upper and lower bridge arms utilize a half-bridge circuit structure with parallel energy storage batteries. This enables bidirectional energy storage charge and discharge management and power conversion in higher voltage and higher power applications. Each submodule includes a half-bridge circuit, an energy storage battery, and a slave FPGA controller. The slave FPGA controller primarily samples voltage and current information from its respective submodule during operation.

[0043] The device enables bidirectional energy storage charge and discharge management and power conversion in higher voltage and higher power scenarios. It can deliver high-quality, low-harmonic power output, reactive power compensation, and power factor correction when urgently needed by coal mine emergency power systems. In charging mode, a single submodule rectifies the AC voltage into the DC voltage required by the energy storage battery. In discharge mode, the DC power generated by the energy storage battery is inverted into AC power by the submodule. The AC voltages of multiple cascaded submodules per phase are superimposed to form low-harmonic AC power.

[0044] The FPGA is mainly responsible for pulse signal distribution, protection logic control, analog and digital conversion (A / D), input / output digital (I / O) signal control, universal asynchronous receiver / transmitter (UART) protocol, and data interaction with the DSP through XINTF; the DSP is mainly responsible for the system's decoupling control, generating modulation waves and other signals, communicating with the touch screen, protection control of the entire system, power-on logic, and pre-charging logic.

[0045] The MMC's main power conversion circuit is a three-phase structure. Each phase includes an upper arm and a lower arm. Each arm consists of a bridge arm inductor connected in series with four submodules. Using a modular cascade structure, the upper and lower arm submodules of each phase are half-bridge circuits connected in parallel with energy storage batteries. This allows for bidirectional energy storage charge and discharge management and power conversion in higher voltage and higher power applications—an advantage that is essential for mining energy storage applications. Each submodule is also equipped with a slave controller (slave FPGA) responsible for collecting voltage, current, and temperature information during operation. In this example, there are 24 slave control boards.

[0046] The slave control board consists of a slave FPGA chip, fiber optic transmitting and receiving circuits, voltage and current detection circuits, temperature detection circuits, analog-to-digital (AD) conversion circuits, and switch driver circuits. The slave control board's fiber optic transmitting and receiving circuits receive data from the master control board and transmit data detected and converted by the slave control board. The voltage and current detection circuits collect voltage and current information during submodule operation. The switch driver circuit is responsible for turning the controllable power switch IGBT on and off. The AD conversion circuit converts the collected information from analog to digital.

[0047] The hardware control system is based on a master controller consisting of a main DSP and FPGA, and coordinated control by slave controllers (slave FPGAs) for each submodule. The master DSP and FPGA are connected via the XINTF external bus to form the master control board. The master control board (master DSP + master FPGA) is connected to the slave control boards (slave FPGAs) of the submodules via optical fiber, enabling communication between them. Data exchange between the master and slave control boards is accomplished using two optical fibers: one for data transmission and the other for data reception.

[0048] The main control board features a DSP and FPGA chip as the computing core, along with fiber optic transmission and reception circuits and a human-computer interaction interface. The master FPGA communicates with the slave control board via these circuits and collaborates with the master DSP to process the upper-level control algorithm. The DSP also features a human-computer interaction interface for interaction with the host computer.

[0049] In the hardware control system, the master control board (master DSP + master FPGA) and slave control boards (slave FPGA) are connected via fiber optic communication for coordinated control. Each submodule's slave controller first collects information such as voltage, current, and temperature through its sampling circuit and transmits this data to the master control board via fiber optic communication. The master controller then processes the data received from the slave control board through an algorithm and sends the results back to the slave control board via fiber optic communication. Based on the instructions, the slave control board generates the corresponding switching control signals for each submodule's switching transistor (IGBT), ensuring reliable system operation.

[0050] The individual FPGA slave control boards assigned to each sub-module have a certain degree of autonomy for each corresponding sub-module. Simple operations can directly distribute the corresponding switch control signals to the controllable power switch tubes (IGBTs) on each half-bridge circuit to achieve conduction and shutdown, without going through the processing of the upper controller, thus realizing valve group-level control.

[0051] The information exchange between the four sub-modules of a single bridge arm (four slave FPGAs) realizes the energy balance within the bridge arm, which is a bridge arm-level control, ensuring that the battery voltages of each sub-module in the bridge arm remain consistent;

[0052] The complex and comprehensive system control algorithm is realized through the coordinated control of the main DSP + main FPGA + 24 slave FPGAs to achieve system-level control, such as when the system has large disturbances or imbalances.

[0053] The hardware control system implements a three-level control system: valve group-level control mainly focuses on the opening and closing of the switch tube; bridge arm-level control mainly undertakes the task of energy balance within the bridge arm, mainly the voltage balance of each sub-module within the bridge arm; system-level control mainly focuses on the calculation and processing of the upper-level system control algorithm.

[0054] MMCs involve multiple IGBTs and other power switching transistors, and the PWM unit provided by the DSP cannot meet actual needs. FPGAs can perform extremely complex timing and combinational logic circuit functions and generate a large number of PWM pulse drive signals. Leveraging the complementary advantages of DSP and FPGA, communicating with the slave control board via optical fiber and adopting a modular approach, they can be expanded according to actual needs, overcoming the shortcomings of existing technologies, such as the poor scalability and difficulty in achieving high-speed and high-precision requirements for complex calculations.

[0055] The above embodiments are preferred examples of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A MMC type mining battery energy storage system power electronic conversion device, characterized in that: include: Three phase units, a main control board and multiple slave control boards connected in parallel, Each of the phase units comprises an upper bridge arm, an upper bridge arm inductor, a lower bridge arm inductor and a lower bridge arm connected in series in sequence, The upper bridge arm and the lower bridge arm each include a plurality of energy storage submodules connected in series, and the number of the energy storage submodules in the upper bridge arm is equal to the number of the energy storage submodules in the lower bridge arm. The energy storage submodule is formed by connecting a half-bridge circuit and an energy storage battery in parallel. The upper bridge arm has an upper bridge arm positive terminal and an upper bridge arm negative terminal, the upper bridge arm positive terminal is the positive terminal of the first energy storage submodule in the upper bridge arm, and the upper bridge arm negative terminal is the negative terminal of the last energy storage submodule in the upper bridge arm. The lower bridge arm has a lower bridge arm positive terminal and a lower bridge arm negative terminal, the lower bridge arm positive terminal is the positive terminal of the first energy storage submodule in the lower bridge arm, and the lower bridge arm negative terminal is the negative terminal of the last energy storage submodule in the lower bridge arm. One end of the upper bridge arm inductor is connected to the negative terminal of the upper bridge arm, and the other end is connected to one end of the lower bridge arm inductor, and the other end of the lower bridge arm inductor is connected to the positive terminal of the lower bridge arm. The number of the slave control boards is equal to the number of the energy storage submodules. One energy storage submodule is connected to one slave control board, and the slave control board is used to collect data of the corresponding energy storage submodule. The main control board is connected to the plurality of slave control boards respectively, and is used to receive the data of the slave control boards and generate a switch control signal according to the data and send the switch control signal to the corresponding slave control board to control the working state of the corresponding energy storage submodule. The main control board includes a main FPGA chip and a DSP connected to the main FPGA chip via XINTF. The main FPGA chip and the DSP cooperate with each other to generate the switch control signal to control the working state of the corresponding energy storage submodule. The half-bridge circuit includes a first controllable power switch tube T1, a second controllable power switch tube T2, a first anti-parallel diode D1, a second anti-parallel diode D2 and an energy storage capacitor C SM , The first controllable power switch tube T1 is connected in series with the second controllable power switch tube T2, the emitter of the first controllable power switch tube T1 is connected to the collector of the second controllable power switch tube T2, and is connected to the cathode of the first anti-parallel diode D1, the collector of the first controllable power switch tube T1 is connected to the anode of the first anti-parallel diode D1 and the energy storage capacitor C SM The positive pole is connected; The collector of the second controllable power switch tube T2 is connected to the anode of the second anti-parallel diode D2, the emitter of the second controllable power switch tube T2 is connected to the cathode of the second anti-parallel diode D2, and is connected to the energy storage capacitor C SM The negative pole is connected to The slave control board includes a slave FPGA chip, an optical fiber transmitting and receiving circuit, a voltage and current detection circuit, a temperature detection circuit, an AD conversion circuit, an IGBT driving and fault return circuit and an IO driving circuit.

2. The MMC type mining battery energy storage system power electronic conversion device according to claim 1 is characterized in that: in, The slave FPGA chip is connected to the main control board, the second controllable power switch tube and the temperature detection circuit. The optical fiber transmitting and receiving circuit is used to receive the data sent by the main control board and send the data detected and converted by the slave control board. The voltage and current detection circuit is used to collect the voltage and current of the energy storage submodule when it is running. The temperature detection circuit is used to collect the temperatures of the first controllable power switch tube T1 and the second controllable power switch tube T2. The AD conversion circuit is used to collect the capacitor voltage of the energy storage submodule. The IGBT driving and fault return circuit is used to drive the first controllable power switch tube T1 and the second controllable power switch tube T2 to be turned on and off and receive fault signals of the first controllable power switch tube T1 and the second controllable power switch tube T2.

3. The MMC type mining battery energy storage system power electronic conversion device according to claim 1 is characterized in that: in, The main control board and the slave control board are connected via two optical fibers for exchanging data, one of the optical fibers controls the sending of data, and the other optical fiber controls the receiving of data.

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