Highly reliable self-powered drive power supply system and fault-tolerant control method

Abstract

The application discloses a high-reliability self-powered driving power supply power supply system and a fault-tolerant control method. An input end of the high-reliability self-powered driving power supply power supply system is connected with a high-voltage direct-current bus of an application system, and an output end is used for supplying power to a driver. The high-reliability self-powered driving power supply power supply system comprises a bus interface converter, an energy storage interface converter, a driving power supply, a top controller and a low-voltage direct-current bus. The bus interface converter of the driving power supply power supply is combined and constructed by using a direct-current transformer module group in series input / parallel output, so that "N+1" redundant operation can be realized, and high reliability is achieved. The driving power supply power supply system is based on a self-powered architecture, insulation design difficulty and insulation cooperation difficulty are low, and the driving power supply power supply system is favorable for free pressure boosting and capacity expansion of a medium and high voltage converter.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology and relates to a highly reliable self-powered drive power supply system and a fault-tolerant control method for the highly reliable self-powered drive power supply system. Background Technology

[0002] Silicon carbide (SiC) is a typical representative of third-generation semiconductor materials. Compared to Si, it has a wider bandgap, higher saturated electron velocity, higher electron mobility, lower dielectric constant, and better conductivity, giving SiC devices significant advantages in high-frequency, high-voltage, and high-temperature applications. In recent years, high-voltage SiC-MOSFETs (10kV / 15kV) have developed rapidly. Compared to Si-IGBTs of the same voltage level, they have higher switching frequencies, faster switching speeds, and lower switching losses, and are hailed as the "game-changer" for next-generation medium- and high-voltage power conversion. Replacing high-voltage Si-IGBTs with high-voltage SiC-MOSFETs can greatly improve the switching frequency, enabling the compactness, miniaturization, and weight reduction of medium- and high-voltage converters.

[0003] High-performance SiC drive modules, including drivers and power supplies, are crucial for fully leveraging the advantages of high-voltage SiC-MOSFETs. The power supply, as the energy source for the SiC drive module, directly impacts the power supply reliability of the SiC-MOSFET driver and indirectly affects the overall reliability of the converter. Considering the high-voltage, high-speed, and high-frequency operating characteristics of high-voltage SiC-MOSFETs, their power supplies must possess high isolation voltage, low coupling capacitance, and high reliability.

[0004] Based on the power supply source, drive power supply systems can be divided into two types: external power supply architecture and self-power supply architecture. In the external power supply architecture, the drive power supply is supplied by an independent external low-voltage DC bus, allowing it to operate independently of the medium- and high-voltage converters and simplifying startup and shutdown sequences. However, the converter's maximum operating voltage cannot exceed the drive power supply's isolation voltage, limiting the converter's voltage expansion capabilities. In the self-power supply architecture, the drive power supply is supplied by distributed high-voltage DC buses within the converter. This not only reduces the difficulty of insulation design and coordination but also facilitates modular voltage expansion of the converter, demonstrating a significant advantage over external power supply drive power supply systems.

[0005] Domestic and international researchers have conducted research on self-powered drive power supply systems. Hu B and Wang J et al. proposed a self-powered drive power supply system based on an active voltage divider in "A self-sustained circuit building block based on 10-kV silicon carbidedevices for high-voltage applications[J].IEEE Journal of Emerging and Selected Topics in Power Electronics,2020,8(3):2801–2811." This method is simple and easy to implement, but the low heat dissipation of the active voltage divider leads to very low conversion efficiency. Self-powered drive power supply systems based on medium-voltage switching transistors have higher efficiency. However, the high cost and limited supply of medium-voltage switching transistors restrict their large-scale application. By replacing the medium-voltage switching transistors with multiple low-voltage switching transistors connected in series, Chen X et al. and Modeer T et al. developed 4kV / 160V and 3kV / 100V self-powered drive power supply systems in "Research on a 4000-V ultrahigh-input switched-mode powersupply using series-connected MOSFETs[J].IEEE Transactions on Power Electronics,2018,33(7):5995–6011." and "High-voltage tapped-inductor buckconverter utilizing an autonomous high-side switch.IEEE Transactions on Industrial Electronics[J],2015,62(5):2868–2878.", respectively. However, the dynamic voltage equalization control of series-connected switching transistors is very difficult, and an open-circuit fault in any switching transistor will cause the converter to fail to operate. Using multi-level technology, Liu J et al. developed a 1kV / 15V self-powered drive power supply system in "Auxiliary power supply formedium / high-voltage and high-power solid-state transformers[J].IEEE Transactions on Power Electronics, 2020, 35(5):4791–4803." This scheme solves the problem of high voltage stress on the switching transistor, but it does not have the ability to operate with fault tolerance.Based on series module voltage equalization technology, Meng T et al. developed a 2.2kV / 24V self-powered drive power supply system in "Investigation and implementation of an input-series auxiliary power supply scheme for high-input-voltage low-power applications[J].IEEE Transactions on Power Electronics,2018,33(1):437–447.", which also achieved the design requirement of using multiple low-voltage switches to replace medium-voltage switching transistors of the same voltage level. However, all the switching transistors need to switch synchronously, which increases the difficulty of controlling the drive timing. In addition, the introduction of a magnetic integrated transformer limits the fault-tolerant operation capability of the self-powered drive power supply system.

[0006] The literature review above shows that publicly available self-powered drive power supply systems suffer from poor fault tolerance or low conversion efficiency. Summary of the Invention

[0007] The purpose of this invention is to propose a highly reliable self-powered drive power supply system with strong fault tolerance.

[0008] Another objective of this invention is to propose a fault-tolerant control method for a highly reliable self-powered drive power supply system, which can achieve uninterrupted power supply under fault conditions.

[0009] The specific technical solution of the present invention is as follows:

[0010] A highly reliable self-powered drive power supply system is disclosed, with its input end connected to the high-voltage DC bus of the application system and its output end supplying power to the driver. The system includes a bus interface converter, an energy storage interface converter, drive power supplies, a top-level controller, and a low-voltage DC bus. The bus interface converter includes a bus interface controller and N DC transformer modules, each of which includes a bypass resistor, a bypass switch, a DC transformer main circuit, and an output diode. The energy storage interface converter includes an energy storage interface main circuit, an energy storage interface controller, and an energy storage unit. M drive power supplies are connected in parallel, each including a drive power supply controller and a drive power supply main circuit; where N≥2 and M≥1.

[0011] The top-level controller receives external start / stop commands (ON) and a sampling signal V of the low-voltage DC bus voltage. bus The fault status signal e fed back by the bus interface controller DCX According to the sampled signal V bus Feedback low-voltage DC bus status signal S busThese are respectively connected to the bus interface controller, energy storage interface controller, and drive power controller, and are based on the fault status signal e. DCX Feedback fault flag signal k FT To the energy storage interface controller;

[0012] The bus interface converter comprises N DC transformer modules connected in series at the input and parallel at the output. The input terminals are connected to the high-voltage DC bus, and the output terminals are connected to the low-voltage DC bus. The bus interface controller receives fault status signals e from the main circuit of the DC transformers. DCX And the received external start / stop command ON and the low-voltage DC bus status signal S fed back by the top-level controller. bus The faulty module is isolated for fault-tolerant power supply, and a fault status signal e is fed back. DCX To the top-level controller;

[0013] The energy storage interface converter is connected to the low-voltage DC bus, and the energy storage interface controller detects the capacity flag signal S of the energy storage unit. ES And received external start / stop commands ON, low-voltage DC bus status signal S bus and fault flag signal k FT Controls the charging and discharging state of the energy storage interface converter;

[0014] The drive power supply has its input terminal connected to the low-voltage DC bus and its output terminal connected to the driver. The drive power supply controller controls the output based on the received low-voltage DC bus status signal S. bus It controls the start and stop of the main circuit of the drive power supply and reports errors.

[0015] Furthermore, in each DC transformer module, the input is connected to a bypass resistor and one input terminal of the DC transformer main circuit, respectively. The bypass resistor and bypass switch are first connected in series and then in parallel to the other input terminal of the DC transformer main circuit. The output is connected in series with a diode and then connected between the low-voltage DC buses. The bus interface controller is connected to the DC transformer main circuit and the bypass switch, respectively. The bus interface controller also outputs the drive command for the bypass switch and the drive signal for the DC transformer main circuit according to the received signal.

[0016] Furthermore, the input terminal of the energy storage interface main circuit is connected to the output terminal of the energy storage unit, and the output terminal is connected to the low-voltage DC bus. The energy storage interface controller is connected to both the energy storage unit and the energy storage interface main circuit. The energy storage interface controller also receives the voltage signal V fed back from the energy storage unit. ES Current signal i ES The drive command sent to the main circuit of the energy storage interface.

[0017] Furthermore, in each drive power supply, the drive power supply controller receives the voltage sampling signal V fed back from the drive power supply main circuit.om , m = 1 ~ M, and send drive commands to the drive power controller.

[0018] Furthermore, the negative terminal of the low-voltage DC bus is connected to the midpoint of the split capacitor of the high-voltage DC bus in the system to ensure that each point in the self-powered drive power supply system has a defined potential.

[0019] Furthermore, the driver is a switching transistor driver in a high-voltage high-power converter with a distributed high-voltage DC bus.

[0020] Furthermore, the DC transformer main circuit in the bus interface converter adopts an isolated PWM DC-DC converter, such as a half-bridge PWM DC-DC converter or a full-bridge PWM DC-DC converter; or an isolated resonant DC-DC converter, such as an LCC resonant DC-DC converter or an LLC resonant DC-DC converter.

[0021] The main circuit of the energy storage interface adopts a bidirectional DC-DC converter, such as a bidirectional Buck / Boost converter or a bidirectional active full-bridge converter.

[0022] The main circuit of the drive power supply adopts a high-isolation PWM converter, such as a high-isolation half-bridge PWM DC-DC converter or a high-isolation full-bridge PWM DC-DC converter; or a high-isolation resonant DC-DC converter, such as a high-isolation LCC resonant DC-DC converter or a high-isolation LLC resonant DC-DC converter; or a contactless converter, such as a series-series compensated contactless resonant DC-DC converter or a parallel-series compensated contactless resonant DC-DC converter.

[0023] The fault-tolerant control method based on the above-mentioned high-reliability self-powered drive power supply system includes the following steps:

[0024] 1) Upon receiving the start / stop command ON=1, the energy storage interface converter soft-starts, and the low-voltage DC bus voltage slowly builds up. When the low-voltage DC bus voltage V is detected... bus When the voltage rises to the rated output voltage of the energy storage interface converter, the low-voltage DC bus status signal S... bus When set to 1, the energy storage interface converter enters the rated discharge condition, the split energy storage capacitors of the high-voltage DC bus begin to precharge, and the output voltage of each DC transformer module in the bus interface converter is slowly established.

[0025] 2) As the high-voltage DC bus voltage increases, the output voltage of each DC transformer module in the bus interface converter rises to its rated value, and the diodes conduct to supply power to the drive power supply; when the top-level controller receives the sampling signal V of the low-voltage DC bus voltage... bus When the rated value is reached, the low-voltage DC bus status signal S is set.bus When the value is 2, the energy storage interface converter enters the standby mode, the bus interface converter enters the rated mode, and the power supply system operates stably.

[0026] 3) When the bus interface controller receives a fault status signal e from the main circuit of a certain DC transformer DCX When the fault occurs, the main circuit of the faulty DC transformer is shut down; and a fault status signal e is fed back. DCX Set the fault flag signal k to the top-level controller. FT Set to 1; simultaneously, the low-voltage DC bus voltage increases, and the low-voltage DC line status S is set. bus When the value is 3, the bus interface converter enters the fault-tolerant operation mode, and the power supply system operates in a fault-tolerant manner;

[0027] 4) When the bus interface controller receives a fault status signal e from the main circuit of a certain DC transformer again... DCX When the fault occurs, the main circuit of the faulty DC transformer is shut down; and a fault status signal e is fed back. DCX Set the fault flag signal k to the top-level controller. FT When the value is 2, the energy storage interface converter enters the rated discharge condition; simultaneously, the low-voltage DC bus voltage further increases. When the low-voltage DC bus voltage increment exceeds the threshold, the low-voltage DC line state S is set. bus If the value is 4, the bus interface converter, drive power supply, and energy storage interface converter will be shut down after the power supply system reports an error.

[0028] Furthermore, when the energy storage interface controller receives the capacity status signal S from the energy storage unit... ES =0, meaning the energy storage capacity is insufficient, then reverse startup charges the energy storage unit through the low-voltage DC bus to the main circuit of the energy storage interface.

[0029] Furthermore, it also includes the step that when the start / stop command ON=0 is received, the bus interface converter, energy storage interface converter and drive power supply all enter the standby / stop mode.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention proposes a highly reliable self-powered drive power supply system. In this drive power supply, the bus interface converter is constructed by combining input series / output parallel DC transformer modules, which can achieve "N+1" redundant operation and has high reliability. Its DC transformer operates at a fixed frequency / fixed duty cycle, which can achieve input voltage self-balancing and output current self-balancing. Its primary-side switching transistor achieves zero-voltage turn-on, and the secondary-side diode achieves zero-current turn-off, which can achieve high-efficiency power conversion.

[0032] 2. The energy storage interface converter in the drive power supply system of the present invention integrates a micro energy storage unit, which has a low cost, can provide black start capability for the power supply system, and realize redundant power supply and uninterrupted power supply for the switching transistor driver, greatly improving the reliability of the drive power supply system.

[0033] 3. The drive power supply system of the present invention is based on a self-powered architecture, which has low difficulty in insulation design and insulation coordination, and is conducive to the free voltage increase and capacity expansion of medium and high voltage converters.

[0034] 4. The power supply system of this invention adopts a two-stage conversion architecture, which has more flexible design freedom. By optimizing the value of the low-voltage DC bus voltage, the self-powered power supply system can achieve the global optimal design of important technical indicators such as conversion efficiency, power density and coupling capacitance.

[0035] 5. This invention proposes a fault-tolerant control method for a highly reliable self-powered drive power supply system. This fault-tolerant control method only needs to sample the low-voltage DC bus voltage and determine its operating state to enable the bus interface converter, energy storage interface converter and drive power supply in the self-powered drive power supply system to operate in a coordinated manner. Under normal operating conditions, it can provide efficient and high-quality power supply to the switching transistor driver, and can provide uninterrupted power supply to the drive power supply under fault conditions.

[0036] 6. The fault-tolerant control method of the present invention can provide high-quality power supply and ensure uninterrupted power supply for the switching transistor drivers in high-voltage high-power converters with distributed high-voltage DC buses, such as modular multilevel converters (MMC), power electronic transformers (PET), and cascaded H-Bridge multilevel converters (CHB-MLC). Attached Figure Description

[0037] Figure 1 Block diagram of a high-reliability self-powered drive power supply system;

[0038] Figure 2 A schematic diagram of some structures in a high-reliability self-powered drive power supply system;

[0039] Figure 3 A circuit example diagram of a portion of the structure in a high-reliability self-powered drive power supply system;

[0040] Figure 4 State diagram for fault-tolerant control method of high-reliability self-powered drive power supply system;

[0041] Figure 5(a) is the control flowchart of the energy storage interface converter;

[0042] Figure 5(b) is the control flowchart of the bus interface converter;

[0043] Figure 6 The output external characteristic curve of the current transformer module;

[0044] Figure 7 The waveform diagram shows the steady-state operation of the bus interface converter. Figure 7 The solid line represents the input voltage waveform, and the dashed line represents the output current waveform.

[0045] Figure 8 This is a dynamic waveform diagram of the bus interface converter under sudden load changes. Figure 8 The solid lines in the diagram represent the input voltage waveform, and the dashed lines represent the output current waveform.

[0046] Figure 9 This is a dynamic waveform diagram of the bus interface converter when the input voltage changes abruptly. Figure 9 The solid lines in the diagram represent the input voltage waveform, and the dashed lines represent the output current waveform.

[0047] Figure 10 The diagram shows the dynamic waveforms of the bus interface converter during the fault module removal process.

[0048] Figure 11 This is a simulation waveform diagram of a high-reliability self-powered drive power supply system using a fault-tolerant control method.

[0049] Figure 12(a) is a system block diagram of a high-reliability self-powered drive power supply system applied to a three-phase MMC converter;

[0050] Figure 12(b) is a system block diagram of a high-reliability self-powered drive power supply system applied to a power electronic transformer;

[0051] Figure 12(c) is a system block diagram of a high-reliability self-powered drive power supply system applied to a cascaded multilevel converter.

[0052] In the diagram, o is the midpoint of the split energy storage capacitor on the high-voltage DC bus, and also the grounding point of the drive power supply system; R n (n = 1, 2, ..., N) represents the bypass resistance of the nth DC transformer module; SW n (n = 1, 2, ..., N) represents the bypass switch for the nth DC transformer module; Q n1 and Q n1 (n = 1, 2, ..., N) represents the primary-side switching transistor of the nth DC transformer module; D Rn1 and D Rn2 (n = 1, 2, ..., N) represents the secondary rectifier diodes of the nth DC transformer module; Lfn and C fn (n = 1, 2, ..., N) represent the output filter inductance and output filter capacitor of the nth DC transformer module, respectively; C sn1 C sn2 C pn1 and C pn2 (n = 1, 2, ..., N) are the four compensation capacitors of the nth DC transformer module; D n (n = 1, 2, ..., N) represents the output diodes of the nth DC transformer module; V bus This represents the low-voltage DC bus voltage; ESIC is the Energy Storage Interfaced Converter; BIC is the Bus Interfaced Converter; DCX is the DC Transformer; ON is the start / stop command for the drive power system, ON=0 indicates shutdown, ON=1 indicates start; S ES S is an indicator of energy storage capacity. ES =0 indicates insufficient energy storage capacity, S ES =1 indicates sufficient energy storage capacity; e DCX This is a fault status signal; k FT For fault flag signals, k FT =0 indicates no fault, k FT =1 indicates a single module failure, k FT =2 indicates a fault in two or more modules; S bus S is the status indicator for the low-voltage DC bus. bus =0 indicates undervoltage, S bus =1 indicates the pre-charge voltage, S bus =2 indicates the rated operating voltage, S bus =3 indicates the fault-tolerant operating voltage, S bus =4 indicates the bus voltage threshold; V inn (n = 1 to N) represents the input voltage of the nth DC transformer module; I on (n = 1 to N) represents the output current of the nth DC transformer module; V om (m=1,2,…M) represents the output voltage of the m-th drive power supply; SOC is the capacity of the energy storage unit. Detailed Implementation

[0053] Example 1:

[0054] The present invention discloses a highly reliable self-powered drive power supply system, wherein the input end is connected to the high-voltage DC bus of the application system, and the output end supplies power to M drivers. The drivers can be switching transistor drivers in high-voltage high-power converters with distributed high-voltage DC buses, such as modular multilevel converters, power electronic transformers, and cascaded multilevel converters.

[0055] like Figure 1 As shown, the drive power supply system includes a bus interface converter, an energy storage interface converter, drive power supplies, a top-level controller, and a low-voltage DC bus. The bus interface converter includes a bus interface controller and N DC transformer modules. Each DC transformer module includes a bypass resistor, a bypass switch, a DC transformer main circuit, and an output diode. The energy storage interface converter includes an energy storage interface main circuit, an energy storage interface controller, and an energy storage unit. M drive power supplies are connected in parallel. Each drive power supply includes a drive power supply controller and a drive power supply main circuit. Each drive power supply controller supplies power to one driver. Where N≥2 and M≥1.

[0056] The top-level controller receives external start / stop commands (ON) and a sampling signal V of the low-voltage DC bus voltage. bus The fault status signal e fed back by the bus interface controller DCX According to the sampled signal V bus Feedback low-voltage DC bus status signal S bus These are respectively connected to the bus interface controller, energy storage interface controller, and drive power controller, and are based on the fault status signal e. DCX Feedback fault flag signal k FT To the energy storage interface controller;

[0057] The bus interface converter is used to convert the high-voltage DC bus voltage to the low-voltage DC bus voltage. DC transformer modules 1 to N adopt an input series / output parallel connection method, which reduces the voltage stress on the switching transistors of each module and evenly distributes the current and thermal stress on the switching transistors. Its input terminal is connected to the high-voltage DC bus, and its output terminal is connected to the low-voltage DC bus. The bus interface controller uses the fault status signal e fed back from the DC transformer main circuit. DCX And the received external start / stop command ON and the low-voltage DC bus status signal S fed back by the top-level controller. bus The faulty module is isolated for fault-tolerant power supply, and a fault status signal e is fed back. DCX To the top-level controller;

[0058] The energy storage interface converter enables bidirectional power transmission. Its functions are: 1) to support the low-voltage DC bus in case of a bus interface converter failure, ensuring uninterrupted power supply to the drive power source; 2) to establish the low-voltage DC bus voltage in the self-powered drive power supply system before the high-voltage DC bus voltage is established, simplifying the startup process of the bus interface main circuit; and 3) to charge the energy storage units when their capacity is low, ensuring sufficient energy for the energy storage units. It is connected to the low-voltage DC bus, and the energy storage interface controller uses the detected capacity flag signal S of the energy storage units... ES And received external start / stop commands ON, low-voltage DC bus status signal S bus and fault flag signal k FT Controls the charging and discharging state of the energy storage interface converter;

[0059] The function of the drive power supply is to provide a stable operating voltage for the driver. Its input terminal is connected to the low-voltage DC bus, and its output terminal is connected to the driver. The drive power supply controller determines the operating voltage based on the received low-voltage DC bus status signal S. bus It controls the start and stop of the main circuit of the drive power supply and reports errors.

[0060] Example 2:

[0061] A further optional design of this embodiment is: such as Figure 1 As shown, in each DC transformer module, the input is connected to the bypass resistor and one input terminal of the DC transformer main circuit, respectively. The bypass resistor and the bypass switch are first connected in series and then in parallel to the other input terminal of the DC transformer main circuit. The output is connected in series with the diode and then connected between the low-voltage DC buses. The bus interface controller is connected to the DC transformer main circuit and the bypass switch, respectively. The bus interface controller also outputs the drive command of the bypass switch and the drive signal of the DC transformer main circuit according to the received signal.

[0062] The input terminal of the energy storage interface main circuit is connected to the output terminal of the energy storage unit, and the output terminal is connected to the low-voltage DC bus. The energy storage interface controller is connected to both the energy storage unit and the energy storage interface main circuit. The energy storage interface controller also receives the voltage signal V fed back by the energy storage unit. ES Current signal i ES The drive command sent to the main circuit of the energy storage interface.

[0063] In each drive power supply, the drive power supply controller receives the voltage sampling signal V fed back from the drive power supply main circuit. om , m = 1 ~ M, and send drive commands to the drive power controller.

[0064] In this example, the negative terminal of the low-voltage DC bus is connected to the midpoint of the split capacitor of the high-voltage DC bus in the system to ensure that each point in the self-powered drive power supply system has a defined potential.

[0065] Example 3:

[0066] This example analyzes the system architecture of the high-reliability self-powered drive power supply system of the present invention. The architecture of some structures in the drive power supply system is as follows: Figure 2 As shown in the diagram. The bus interface converter is powered by the high-voltage DC bus, and the outputs of both the bus interface converter and the energy storage interface converter are connected to the low-voltage DC bus. The M drive power supplies are all powered by the low-voltage DC bus, and their outputs are connected to the M switching transistor drivers. The bus interface converter consists of N DC transformer modules connected in series at the input and parallel at the output. It can automatically achieve input voltage self-balancing and output current self-balancing, reducing the voltage stress on the switching transistors of each module and eliminating the need for load voltage / current sharing control.

[0067] Figure 3 This is an example diagram of the high-reliability self-powered drive power supply system proposed in this invention. In the diagram, the DC transformer module in the bus interface converter uses a resonant DC-DC converter, the energy storage interface converter uses a Boost / Buck converter with bidirectional power transfer, and the drive power supply uses a half-bridge PWM DC-DC converter. It should be noted that the primary circuit of the DC transformer module uses a symmetrical half-bridge structure, the secondary circuit uses a full-wave rectification structure, and the transformer uses a series-parallel type with full capacitance compensation; each DC transformer contains four compensation capacitors, including: C sn1 C sn2 C pn1 and C pn2 (n=1~N), used to compensate for the leakage inductance and self-inductance of the transformer, and to adjust the phase of the fundamental component of the primary side bridge arm voltage and the fundamental component of the primary side resonant current; C sn1 One end is connected to the midpoint of the primary circuit bridge arm, and the other end is connected to the corresponding terminal of the primary winding of the transformer; C sn2 C pn1 and C pn2 One end of each diode is connected to the cathode of the secondary output filter capacitor, and the other end is connected to the center tap of the secondary winding of the transformer. The rectifier diode D... Rn1 anode and rectifier diode D Rn2 The anode. V bus This refers to the low-voltage DC bus voltage; e DCX Indicates a fault status signal; in the input voltage of the bus interface converter, V inn (n=1,2,…N) represents the input voltage of the nth DC transformer module; in the output current of the bus interface converter, I on (n = 1, 2, ..., N) represents the output current of the nth DC transformer module; V om (m=1,2,…M) represents the output voltage of the m-th driving power supply.

[0068] Example 4:

[0069] A further optional design of this embodiment is that the DC transformer main circuit in the bus interface converter adopts an isolated PWM DC-DC converter, such as a half-bridge PWM DC-DC converter or a full-bridge PWM DC-DC converter; or an isolated resonant DC-DC converter, such as an LCC resonant DC-DC converter or an LLC resonant DC-DC converter.

[0070] The main circuit of the energy storage interface adopts a bidirectional DC-DC converter, such as a bidirectional Buck / Boost converter or a bidirectional active full-bridge converter.

[0071] The main circuit of the drive power supply needs to have high electrical isolation capability (>3kV) and small primary-secondary coupling capacitance (<5pF). It should adopt a high-isolation PWM converter, such as a high-isolation half-bridge PWM DC-DC converter or a high-isolation full-bridge PWM DC-DC converter; or a high-isolation resonant DC-DC converter, such as a high-isolation LCC resonant DC-DC converter or a high-isolation LLC resonant DC-DC converter; or a contactless converter, such as a series-series compensated contactless resonant DC-DC converter or a parallel-series compensated contactless resonant DC-DC converter.

[0072] Example 5:

[0073] This embodiment provides a fault-tolerant control method for a highly reliable self-powered drive power supply system. This fault-tolerant control method can provide high-quality power supply and ensure uninterrupted power supply for the switching transistor drivers in high-voltage high-power converters with distributed high-voltage DC buses, such as modular multilevel converters, power electronic transformers, and cascaded multilevel converters.

[0074] The fault-tolerant control method includes the following steps:

[0075] 1) Upon receiving the start / stop command ON=1, the energy storage interface converter soft-starts, and the low-voltage DC bus voltage slowly builds up. When the low-voltage DC bus voltage V is detected... bus When the voltage rises to the rated output voltage of the energy storage interface converter, the low-voltage DC bus status signal S... bus When set to 1, the energy storage interface converter enters the rated discharge condition, the split energy storage capacitors of the high-voltage DC bus begin to precharge, and the output voltage of each DC transformer module in the bus interface converter is slowly established.

[0076] 2) As the high-voltage DC bus voltage increases, the output voltage of each DC transformer module in the bus interface converter rises to its rated value, and the diodes conduct to supply power to the drive power supply; when the top-level controller receives the sampling signal V of the low-voltage DC bus voltage... busWhen the rated value is reached, the low-voltage DC bus status signal S is set. bus When the value is 2, the energy storage interface converter enters the standby mode, the bus interface converter enters the rated mode, and the power supply system operates stably.

[0077] 3) When the bus interface controller receives a fault status signal e from the main circuit of a certain DC transformer DCX When the fault occurs, the main circuit of the faulty DC transformer is shut down; and a fault status signal e is fed back. DCX Set the fault flag signal k to the top-level controller. FT Set to 1; simultaneously, the low-voltage DC bus voltage increases, and the low-voltage DC line status S is set. bus When the value is 3, the bus interface converter enters the fault-tolerant operation mode, and the power supply system operates in a fault-tolerant manner;

[0078] 4) When the bus interface controller receives a fault status signal e from the main circuit of a certain DC transformer again... DCX When the fault occurs, the main circuit of the faulty DC transformer is shut down; and a fault status signal e is fed back. DCX Set the fault flag signal k to the top-level controller. FT When the value is 2, the energy storage interface converter enters the rated discharge condition; simultaneously, the low-voltage DC bus voltage further increases. When the low-voltage DC bus voltage increment exceeds the threshold, the low-voltage DC line state S is set. bus If the value is 4, the bus interface converter, drive power supply, and energy storage interface converter will be shut down after the power supply system reports an error.

[0079] The fault-tolerant control method further includes the following steps: when the energy storage interface controller receives the capacity status signal S fed back from the energy storage unit... ES =0, meaning the energy storage capacity is insufficient, then reverse startup charges the energy storage unit through the low-voltage DC bus to the main circuit of the energy storage interface. When the start / stop command ON=0 is received, the bus interface converter, energy storage interface converter, and drive power supply all enter standby / stop mode.

[0080] Example 6:

[0081] This embodiment analyzes the changing states of the energy storage interface converter (hereinafter referred to as ESIC) and the bus interface converter (hereinafter referred to as BIC) in the fault-tolerant control method of this invention. For example... Figure 4 As shown, the ESIC has four states: standby, soft start, discharge operation, and charging operation, while the BIC has four states: shutdown, startup, rated operation, and fault-tolerant operation.

[0082] Initially, ESIC and BIC are in standby / power-off state.

[0083] When a system boot command is received (ON=1), ESIC switches to soft boot mode, V busGradually rising.

[0084] When V bus When the voltage rises to the rated output voltage of ESIC (S bus =1), ESIC switches to discharge operation mode, and BIC switches to startup mode. Afterwards, the converter starts working, the high-voltage bus voltage gradually builds up, and the BIC output voltage rises accordingly. Due to the reverse cutoff of the output diode, V bus Maintain the ESIC rated output voltage value unchanged until the BIC output voltage is higher than the ESIC rated output voltage.

[0085] When V bus When the voltage rises to the rated output voltage of the BIC (S) bus =2), ESIC switches to standby mode, and BIC switches to rated operating mode.

[0086] When a fault occurs in the main circuit of a DC transformer, k FT The value will be set to 1. After the faulty module is disconnected, the low-voltage DC bus voltage will increase (S). bus =3), BIC switches to fault-tolerant operation mode.

[0087] When two or more DC transformer main circuit faults occur, k FT The value will be set to 2, and ESIC will switch to discharge operation mode. After the faulty module is further disconnected, the low-voltage DC bus voltage increment exceeds the threshold (S). bus =4). To protect the switching transistor, the BIC switches to the shutdown state. At this time, the low-voltage DC bus is controlled by the ESIC to achieve uninterrupted power supply. The ESIC shuts down after the power supply system reports an error.

[0088] It is worth noting that when the energy storage capacity is insufficient (S ES When =0), the ESIC in standby mode switches to charging mode until the energy storage capacity is sufficient (S). ES =1).

[0089] It should also be noted that when a power-off command (ON=0) is received, regardless of the state of ESIC and BIC, the system switches to standby / stop mode.

[0090] Figure 5(a) shows the control flowchart of the Energy Storage Interface Converter (ESIC), and Figure 5(b) shows the control flowchart of the Bus Interface Converter (BIC).

[0091] The ESIC process can be divided into four steps:

[0092] Step 1 (ESIC Soft Start): Upon receiving the system startup command (ON=1), ESIC enters the soft start state.

[0093] Step 2 (ESIC startup complete / standby operation): Continuously monitor the low-voltage DC bus status signal S bus When S bus When the value is 2, ESIC is in standby mode.

[0094] Step 3 (ESIC Workflow): This includes two sub-workflows: (a) electron charging workflow and (b) electron discharging workflow.

[0095] i) Determine if the system start / stop command is ON. If a system shutdown command is received (ON=0), proceed directly to step four.

[0096] ii) Determine the fault flag k FT If two or more DC transformer main circuit faults occur (k FT =2), ESIC enters the discharge working flow to support the low-voltage DC bus. After entering this sub-working flow, ESIC maintains discharge operation until the error ends and it re-enters standby mode. When it receives a system shutdown command (ON=0), ESIC directly exits the entire working flow and proceeds to step four;

[0097] iii) Determine the energy storage capacity indicator S ES If the energy storage capacity is sufficient (S ES If the value is 1), then return to the workflow start position;

[0098] iv) If the energy storage capacity is insufficient (S ES If the fault count flag k is 0, then ESIC enters the charging sub-workflow to charge the energy storage unit. Upon entering this sub-workflow, the first step is to check the fault count flag k. FT With energy storage capacity status indicator S ES If two or more DC transformer main circuit faults occur (k FT =2) or energy storage charging completed (S ES If the system power-off command is received (ON=1), then ESIC will exit the charging sub-workflow and return to the start position of the workflow. Then, it checks if the system power-off command is ON. If a system power-off command is received (ON=0), then the entire workflow will exit and proceed to step four. Otherwise, ESIC will return to the start position of the charging sub-workflow.

[0099] Step 4 (ESIC Standby): ESIC enters standby mode, and the process ends.

[0100] The BIC operation process can be divided into four steps:

[0101] Step 1 (BIC Startup): Continuously monitor the system start / stop command ON and the low-voltage DC bus status signal S. bus When the low-voltage DC bus voltage reaches the ESIC rated output (ON=1 and S...) bus =1), BIC starts.

[0102] Step 2 (BIC Operation): When the low-voltage DC bus voltage reaches the BIC rated output, S bus =2, BIC enters working state.

[0103] Step 3 (BIC Workflow):

[0104] i) Determine if the system start / stop command is ON. If a system shutdown command is received (ON=0), exit the workflow and proceed to step four.

[0105] ii) Determine if a faulty DC transformer main circuit exists. If it does, locate and disconnect the faulty module.

[0106] iii) Determine the status signal S of the low-voltage DC bus bus If S bus If the result is 4, exit the workflow and proceed to step four. Otherwise, return to the beginning of the workflow.

[0107] Step 4 (BIC Shutdown): Shut down the BIC; the process ends.

[0108] As can be seen from the flowchart above, by adopting the fault-tolerant control method proposed in this invention, it is only necessary to sample the low-voltage DC bus voltage and determine its working state to enable multiple converters in the self-powered drive power supply system to operate in a coordinated manner, so as to provide uninterrupted power supply to the drive power supply under fault conditions.

[0109] Test Example 1:

[0110] This test embodiment uses simulation experiments to study the output characteristics of the DC transformer module in the bus interface converter. The main parameters used in the simulation are as follows:

[0111] The main parameters used in this simulation experiment are as follows:

[0112] • High-voltage DC bus voltage: 6kV

[0113] Low-voltage DC bus voltage: 48V

[0114] • Drive voltage output voltage: 24V

[0115] Rated power: 100W

[0116] • Number of DC transformer modules: N = 6

[0117] • Number of drive power supplies: M = 2

[0118] • Switching device: IMBF170R650M1

[0119] • Switching frequency: 100kHz

[0120] • Transformer primary leakage inductance: 0.05μH

[0121] • Output filter inductance: 10μH

[0122] • Output filter capacitor: 47μ

[0123] Figure 6 The output characteristic curves of the DC transformer module are presented. Figure 6 It can be seen that when the load increases from no load to full load, the output voltage drops from 49.9V to 48.0V, which approximately achieves constant voltage output.

[0124] Figures 7-10 The steady-state and dynamic operating waveforms of the self-powered drive power supply system in Test Example 1 are presented.

[0125] Figure 7 The steady-state operating waveforms of the bus interface converter are presented. In the figure, the solid line represents the input voltage waveform, and the dashed line represents the output current waveform. It can be seen that during steady-state operation, the input voltage of each DC transformer module is 1kV, and the output current is approximately 0.35A. Although no voltage / current sharing measures are adopted, the 6-channel DC transformer module achieves steady-state self-balancing of the input voltage and the output current.

[0126] Figure 8 The waveforms of the bus interface converter are shown when the total load changes abruptly between 20% of the full load current and the full load current. In the figure, the solid line represents the input voltage waveform, and the dashed line represents the output current waveform. It can be seen that during the load change, the input voltage of each DC transformer module remains at 1kV, achieving dynamic self-balancing of the input voltage; the output current of each DC transformer module is equal and increases (or decreases) proportionally with the total load current, achieving dynamic self-balancing of the output current.

[0127] Figure 9 The operating waveforms of the bus interface converter are shown when the total input voltage varies between 90% and 110% of the rated voltage. In the figure, the solid line represents the input voltage waveform, and the dashed line represents the output current waveform. It can be seen that during the input voltage variation, the input voltage of each DC transformer module remains equal and increases (or decreases) proportionally with the total input voltage, achieving dynamic self-balancing of the input voltage; the output current of each DC transformer module remains approximately 0.35A, achieving dynamic self-balancing of the output current.

[0128] Figure 10The dynamic operating waveforms of the bus interface converter during the fault module disconnection process are presented. In the figure, the solid line represents the input voltage waveform, and the dashed line represents the output current waveform. It can be seen that during the fault module disconnection process, the input voltage of the fault module gradually decreases from 1kV to 0, while the input voltage of the other modules gradually increases from 1kV to 1.2kV, thus redistributing the total input voltage; the output current of the fault module drops directly to 0, while the output current of the other modules immediately increases from 0.35A to 0.41A, redistributing the total load current.

[0129] Test Example 2:

[0130] This test embodiment uses simulation experiments to study the simulated waveforms of a high-reliability self-powered drive power supply system under different operating conditions. The simulation experiment includes the entire process of the drive power supply system from startup to shutdown, and incorporates key events and key times, including energy storage unit charging, single DC transformer module failure, and multiple DC transformer module failures, such as… Figure 11 As shown, the details are as follows:

[0131] [t1,t2]: At time t1, the self-powered drive power supply system starts (ON=1), the energy storage interface converter is soft-started, and V bus The output increases slowly and linearly. At time t2, the energy storage interface converter output reaches its rated output, S bus Set to 1.

[0132] [t2,t3]: Starting from time t2, the bus interface converter starts up, and its output voltage rises. During this period, V bus Controlled by the energy storage interface converter, the energy storage unit is in a discharging state. At time t3, the output of the bus interface converter reaches the rated output of the energy storage interface converter, S bus Set to 2. Afterward, the bus interface converter output continues to rise until it reaches steady-state operation. It should be noted that the steady-state output voltage of the bus interface converter is slightly higher than the rated output voltage of the energy storage interface converter.

[0133] [t3,t4]: The energy storage interface converter returns to standby mode, and the power supply bus is powered by the bus interface converter.

[0134] [t4,t5]: At time t4, if the SOC is detected to be below the lower threshold, the energy storage interface converter enters the charging state and charges the energy storage unit according to the procedure of trickle charging - constant current charging - constant voltage charging - charging termination. Note that the charging simulation takes a long time, so 90% is taken as the upper threshold of SOC (i.e., charging ends when SOC = 90%).

[0135] [t5,t6]: The energy storage unit finishes charging, and the energy storage interface converter returns to standby mode. During this period, the drive power supply bus is still powered by the bus interface converter.

[0136] [t6,t7]: At time t6, if a DC transformer module fails, then k will be... FT Set to 1. After the faulty module is disconnected, the bus interface converter enters fault-tolerant operation mode, V bus Rise. After re-entering steady state, S will... bus Set it to 3.

[0137] [t7,t8]: At time t7, if the DC transformer module reappears, then k will be... FT When set to 2, the energy storage interface converter re-enters the discharge mode. After the faulty module is disconnected, V... bus It will rise further. When its increment exceeds the threshold, S will... bus When set to 4, the bus interface converter stops working.

[0138] [t8,t9]:V bus It is again controlled by the energy storage interface converter. At time t8, V bus The voltage drops to the rated output voltage of the energy storage interface converter. At this time, S... bus Reset to 1. At time t9, a shutdown command (ON=0) is received, and the energy storage interface converter returns to standby mode.

[0139] Based on the simulation results above, it can be seen that by adopting the fault-tolerant control method proposed in this invention, the bus interface converter and the energy storage interface converter can work well together under fault conditions, realizing the highly reliable fault-tolerant operation of the self-powered drive power supply system.

[0140] Application examples:

[0141] Figures 12(a) to 12(c) Application examples of the high-reliability self-powered drive power supply system proposed in this invention in modular multilevel converters, power electronic transformers, and cascaded multilevel converters are given respectively. It can be seen that by connecting the self-powered drive power supply system between the distributed high-voltage DC bus and the switching transistor driver, high-quality self-powering of the switching transistor driver can be achieved. Therefore, the self-powered drive power supply system proposed in this invention has good versatility and scalability, and can be applied to various medium- and high-voltage converters with distributed high-voltage DC buses.

Claims

1. A highly reliable self-powered drive power supply system, wherein the input terminal is connected to the high-voltage DC bus of the application system, and the output terminal supplies power to the driver, characterized in that: It includes a bus interface converter, an energy storage interface converter, a drive power supply, a top-level controller, and a low-voltage DC bus; the bus interface converter includes a bus interface controller and N Each DC transformer module includes a bypass resistor, a bypass switch, a DC transformer main circuit, and an output diode; the energy storage interface converter includes an energy storage interface main circuit, an energy storage interface controller, and an energy storage unit; the drive power supply is connected in parallel with... M Each drive power supply includes a drive power supply controller and a drive power supply main circuit. in N≥2, M≥1 ; The top-level controller receives external start / stop commands (ON) and sampling signals of the low-voltage DC bus voltage. V bus Fault status signals fed back by the bus interface controller e DCX According to the sampling signal V bus Feedback low-voltage DC bus status signal S bus The signals are respectively sent to the bus interface controller, energy storage interface controller, and drive power controller, and are based on the fault status signals. e DCX Feedback fault flag signal k FT To the energy storage interface controller; The bus interface converter, wherein N Each DC transformer module adopts a series input / parallel output connection method. The input terminal is connected to the high-voltage DC bus, and the output terminal is connected to the low-voltage DC bus. The bus interface controller responds to fault status signals fed back from the DC transformer main circuit. e DCX As well as the received external start / stop command ON and the low-voltage DC bus status signal fed back by the top-level controller. S bus The system controls the disconnection of faulty modules for fault-tolerant power supply, while simultaneously feeding back fault status signals. e DCX To the top-level controller; The energy storage interface converter is connected to the low-voltage DC bus, and the energy storage interface controller detects the capacity flag signal S of the energy storage unit. ES And received external start / stop commands ON, low-voltage DC bus status signals S bus and fault indicator signals k FT Controls the charging and discharging state of the energy storage interface converter; The drive power supply has its input terminal connected to the low-voltage DC bus and its output terminal connected to the driver. The drive power supply controller controls the output based on the received low-voltage DC bus status signal. S bus Controls the start and stop of the main circuit of the drive power supply and reports errors; In each DC transformer module, the input is connected to the bypass resistor and one input terminal of the DC transformer main circuit, respectively. The bypass resistor and the bypass switch are first connected in series and then in parallel to the other input terminal of the DC transformer main circuit. The output is connected in series with the diode and then connected between the low-voltage DC buses. The bus interface controller is connected to the DC transformer main circuit and the bypass switch, respectively. The bus interface controller also outputs the drive command of the bypass switch and the drive signal of the DC transformer main circuit according to the received signal. The negative terminal of the low-voltage DC bus is connected to the midpoint of the split capacitor of the high-voltage DC bus in the system to ensure that each point in the self-powered drive power supply system has a definite potential.

2. The high-reliability self-powered drive power supply system according to claim 1, characterized in that: The input terminal of the energy storage interface main circuit is connected to the output terminal of the energy storage unit, and the output terminal is connected to the low-voltage DC bus. The energy storage interface controller is connected to both the energy storage unit and the energy storage interface main circuit. The energy storage interface controller also receives the voltage signal fed back from the energy storage unit. V ES and current signal i ES And send drive commands to the main circuit of the energy storage interface.

3. The high-reliability self-powered drive power supply system according to claim 1, characterized in that: In each drive power supply, the drive power supply controller receives the voltage sampling signal fed back from the drive power supply main circuit. V om , m =1~ M And send drive commands to the power controller.

4. The high-reliability self-powered drive power supply system according to claim 1, characterized in that: The driver is a switching transistor driver in a high-voltage high-power converter with a distributed high-voltage DC bus.

5. The high-reliability self-powered drive power supply system according to claim 1, characterized in that: The DC transformer main circuit in the bus interface converter adopts an isolated PWM DC-DC converter, such as a half-bridge PWM DC-DC converter or a full-bridge PWM DC-DC converter; or an isolated resonant DC-DC converter, such as an LCC resonant DC-DC converter or an LLC resonant DC-DC converter. The main circuit of the energy storage interface adopts a bidirectional DC-DC converter, such as a bidirectional Buck / Boost converter or a bidirectional active full-bridge converter. The main circuit of the drive power supply adopts a high-isolation PWM converter, such as a high-isolation half-bridge PWM DC-DC converter or a high-isolation full-bridge PWM DC-DC converter; or a high-isolation resonant DC-DC converter, such as a high-isolation LCC resonant DC-DC converter or a high-isolation LLC resonant DC-DC converter; or a contactless converter, such as a series-series compensated contactless resonant DC-DC converter or a parallel-series compensated contactless resonant DC-DC converter.

6. A fault-tolerant control method for a high-reliability self-powered drive power supply system according to any one of claims 1 to 5, characterized in that: Includes the following steps: 1) Upon receiving the start / stop command ON=1, the energy storage interface converter soft-starts, and the low-voltage DC bus voltage slowly builds up. When the low-voltage DC bus voltage is detected... V bus When the voltage rises to the rated output voltage of the energy storage interface converter, the low-voltage DC bus status signal will be... S bus When set to 1, the energy storage interface converter enters the rated discharge condition, the split energy storage capacitors of the high-voltage DC bus begin to precharge, and the output voltage of each DC transformer module in the bus interface converter is slowly established. 2) As the high-voltage DC bus voltage increases, the output voltage of each DC transformer module in the bus interface converter rises to its rated value, and the diodes conduct to supply power to the drive power supply; when the top-level controller receives the sampling signal of the low-voltage DC bus voltage... V bus Set the low-voltage DC bus status signal when the rated value is reached. S bus When the value is 2, the energy storage interface converter enters the standby mode, the bus interface converter enters the rated mode, and the power supply system operates stably. 3) When the bus interface controller receives a fault status signal from the main circuit of a DC transformer. e DCX In this case, shut down the main circuit of the faulty DC transformer; And feedback fault status signal e DCX Set the fault flag signal at the top-level controller. k FT Set to 1; simultaneously, the low-voltage DC bus voltage increases, and the low-voltage DC line status is set. S bus When the value is 3, the bus interface converter enters the fault-tolerant operation mode, and the power supply system operates in a fault-tolerant manner; 4) When the bus interface controller receives a fault status signal from the main circuit of a certain DC transformer again e DCX In this case, shut down the main circuit of the faulty DC transformer; And feedback fault status signal e DCX Set the fault flag signal at the top-level controller. k FT When the value is 2, the energy storage interface converter enters the rated discharge condition; simultaneously, the low-voltage DC bus voltage further increases. When the low-voltage DC bus voltage increment exceeds the threshold, the low-voltage DC line status is set. S bus If the value is 4, the bus interface converter, drive power supply, and energy storage interface converter will be shut down after the power supply system reports an error.

7. The fault-tolerant control method according to claim 6, characterized in that: It also includes the step of the energy storage interface controller receiving the capacity status signal fed back from the energy storage unit. S ES =0, meaning the energy storage capacity is insufficient, then reverse startup charges the energy storage unit through the low-voltage DC bus to the main circuit of the energy storage interface.

8. The fault-tolerant control method according to claim 6, characterized in that: It also includes the step that when the start / stop command ON=0 is received, the bus interface converter, energy storage interface converter and drive power supply all enter the standby / stop mode.

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