Fault diagnosis and automatic fault tolerance system and method

Abstract

This invention provides a fault diagnosis and automatic fault-tolerance system and method. The system includes: a main control module and N control modules; the control modules are used to detect whether a buck converter has a fault and the type of fault based on the switch status and voltage value; and when the buck converter is detected to be working normally, they send a first control signal to the main control module; the main control module is used to calculate the operating current command and interleaved conduction angle of each buck converter based on the number M of first control signals received; and send the operating current command and interleaved conduction angle to the control module that outputs the first control signal; the M control modules are also used to form a new daisy-chain communication structure based on the operating current command and interleaved conduction angle to drive the buck converter to work, which can quickly locate faults, isolate faults, automatically update the DC current and delay conduction angle increments, realize the safe, reliable and automatic interleaved operation of the hydrogen production power supply, and ensure that the output ripple of the hydrogen production power supply is always minimized.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, and in particular to a fault diagnosis and automatic fault-tolerant system method. Background Technology

[0002] Developing new energy hydrogen production technologies is of great significance for achieving my country's energy transition and accelerating energy production and consumption. With the continuous maturation of hydrogen production technology, developing large-capacity hydrogen production equipment has become a future trend. To support large-capacity hydrogen production equipment, a stable and reliable power supply needs to be designed. Hydrogen production equipment uses DC power. To improve the conversion efficiency of electrical energy and the reliability of the power supply equipment, a simple step-down converter circuit has unparalleled advantages. However, a single step-down converter cannot be directly applied to high-power applications, while an interleaved parallel structure can effectively solve this problem.

[0003] For megawatt-level hydrogen production power supplies, in addition to adopting multiphase interleaved parallel connections, it is also necessary to consider the withstand voltage, current rating, and maximum junction temperature limits of the switching devices on each branch. Typically, several switching modules still need to be connected in parallel for each phase switch. The reliability and safety of hydrogen production power supplies composed of multiphase interleaved connections and multiple sets of switches in parallel are the foundation for ensuring the efficient operation of electrolyzers, and they should have online fault detection and automatic fault tolerance capabilities.

[0004] In hydrogen production power supplies, capacitor short-circuit faults are the most common type of failure, mainly caused by capacitor aging, which limits the lifespan of the hydrogen production power supply. In addition, the failure rate of semiconductor switches is also extremely high, accounting for 30% to 35% of all converter failures.

[0005] Therefore, it is necessary to provide a fault diagnosis and automatic fault-tolerant system and method for hydrogen production power sources. Summary of the Invention

[0006] Therefore, it is necessary to provide a fault diagnosis and automatic fault-tolerance system to address the aforementioned technical problems.

[0007] A fault diagnosis and automatic fault-tolerant system is applied to a hydrogen production power supply with multiphase interleaving and multiple sets of switches in parallel. The hydrogen production power supply includes N parallel step-down converters. The system includes: a main control module and N control modules.

[0008] Each of the control modules is connected to one of the buck converters, and each of the control modules is also connected to the main control module;

[0009] The control module is used to detect the switching state of the switching transistors in the buck converter and the voltage value of the diodes in the buck converter; based on the switching state and the voltage value, it detects whether the buck converter has malfunctioned and the type of malfunction; and when it detects that the buck converter is working normally, it sends a first control signal to the main control module.

[0010] The main control module is used to count the number M of the first control signals received, M≤N; calculate the operating current command and interleaved conduction angle of each buck converter based on the number M of the first control signals received; and send the operating current command and the interleaved conduction angle to the control module that outputs the first control signal.

[0011] The M control modules are also used to form a new daisy-chain communication structure based on the operating current command and the staggered conduction angle to drive the buck converter to work.

[0012] In one embodiment, the control module detects whether the buck converter has malfunctioned and the type of malfunction based on the switch state and the voltage value as follows:

[0013] When s(t) = 0 and U is detected D (t)>U Dth1 If the capacitor of the buck converter is short-circuited, then it is determined that U is faulty. Dth1 =U do +i L *r short s(t) = 0 indicates that the switch is in the off state, U D (t) represents the diode voltage, U Dth1 i is the voltage threshold of the diode. L For inductor current, r short This is the short-circuit impedance of the capacitor;

[0014] When s(t) = 0 and U is detected D If (t) > 0, then the switching transistor of the buck converter is determined to have a short circuit fault;

[0015] When s(t) = 1 and U is detected D When s(t) > 0, it is determined that all the switching transistors of the buck converter have an open circuit fault, where s(t) = 0 indicates that the switching transistors are in the off state;

[0016] When s(t) = 1 and U is detected th2 D If (t) < 0, then the diode of the buck converter is determined to have a short-circuit fault, where U th2 =-U​in +r s *i s,max U in Input voltage;

[0017] When s(t) = 0 and U D (t)>U th3 AndU th3 =4U f,max If so, it is determined that all diodes in the buck converter have an open-circuit fault, where U f,max Maximum instantaneous pre-voltage of the diode.

[0018] In one embodiment, the control module is further configured to detect the resistance Z of the thermistor in the buck converter. thIGBTi When Z thIGBTi >Z th130 If the diode of the buck converter is open-circuit faulted, then Z is determined to be faulty. th130 This is the open-circuit threshold of the thermistor at 130℃.

[0019] In one embodiment, each of the control modules has its own communication unit, which is used to realize signal transmission between the control modules, so that the M control modules form a new daisy-chain communication structure according to the received operating current command and the staggered conduction angle.

[0020] In one embodiment, the control module is configured to send a second control signal to the main control module when a fault is detected in the buck converter, wherein the first control signal is a low-level signal and the second control signal is a high-level signal.

[0021] In one embodiment, each of the control modules includes an input / output switch, a NOR gate, a logic judgment unit, a control unit, and a resistor;

[0022] The input terminal of the logic judgment unit is connected to a buck converter. The output terminal of the logic judgment unit is connected to the first input terminal of the NOR gate. The second input terminal of the NOR gate is connected to the power supply through a resistor. The second terminal of the NOR gate is also grounded through the input / output switch. The output terminal of the NOR gate is connected to the input terminal of the main control module. The output terminal of the main control module is connected to the input terminal of the control unit. The control unit is used to drive the buck converter to work. The logic judgment unit is used to determine whether the buck converter has malfunctioned.

[0023] In one embodiment, each of the buck converters includes a plurality of switching transistors, a plurality of diodes, and an inductor. The number of switching transistors is equal to the number of diodes. The first terminal of each switching transistor is connected to the positive terminal of the input power supply. The second terminal of each switching transistor is connected to the negative terminals of the plurality of diodes. The negative terminal of each diode is connected to the negative terminal of the input power supply. The second terminal of the second terminal of the switching transistor is also connected to the first terminal of the inductor. The second terminals of each inductor are interconnected.

[0024] In one embodiment, the switching transistor is an IGBT.

[0025] In one embodiment, there are nine buck converters, and each buck converter contains six switching transistors and six diodes.

[0026] A fault diagnosis and automatic fault tolerance method, applied to the fault diagnosis and automatic fault tolerance system described in any of the above embodiments, the method comprising:

[0027] The switching state of the switching transistors in the buck converter is obtained, and the voltage value of the diodes in the buck converter is detected.

[0028] Based on the switch status and the voltage value, detect whether the buck converter has malfunctioned and the type of malfunction;

[0029] The number M of the buck converters that are operating normally;

[0030] Based on the number M of the buck converters in normal operation, the operating current command and interleaved conduction angle of each buck converter are calculated.

[0031] The operating current command and the interleaved conduction angle are sent to M control modules, so that the control modules form a new daisy-chain communication structure according to the operating current command and the interleaved conduction angle, and drive the buck converter to work.

[0032] The aforementioned fault diagnosis and automatic fault-tolerant system, by setting a control module on each buck converter, diagnoses whether the buck converter has malfunctioned based on the collected switching status of the switching transistors and the voltage values ​​of the diodes. The main control module counts the number of buck converters that are operating normally and, based on the number of normally operating buck converters, redistributes the operating current and interleaved conduction angle of the buck converters according to the daisy-chain communication structure. This achieves fault isolation and automatic fault tolerance of the hydrogen production power supply. In other words, through the coordinated cooperation of fault monitoring technology and automatic fault-tolerant control technology, faults can be quickly located and isolated, and the DC current and delay conduction angle increments can be automatically updated to achieve safe, reliable, and automatic interleaved operation of the hydrogen production power supply, ensuring that the output ripple of the hydrogen production power supply is always minimized. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a structural block diagram of a fault diagnosis and automatic fault-tolerance system in one embodiment of the present invention;

[0035] Figure 2 The circuit diagram of a hydrogen production power supply with multiphase interleaving and a set of switches in parallel;

[0036] Figure 3 Circuit diagram of a hydrogen production power supply with multiphase interleaving and multiple sets of switches in parallel;

[0037] Figure 4 This is a circuit diagram of a logic judgment unit in one embodiment of the present invention;

[0038] Figure 5 This is a structural block diagram of the fault diagnosis and automatic fault tolerance system in another embodiment of the present invention;

[0039] Figure 6 This is a structural block diagram of a daisy-chain communication structure formed by N control modules in one embodiment of the present invention;

[0040] Figure 7 This is a structural block diagram of a daisy-chain communication structure formed by M control modules in one embodiment of the present invention;

[0041] Figure 8 This is a structural block diagram of a fault diagnosis and automatic fault-tolerance system in another embodiment of the present invention;

[0042] Figure 9This is a flowchart illustrating a fault diagnosis and automatic fault tolerance method in one embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] This application provides a fault diagnosis and automatic fault tolerance system, which is applied to a hydrogen production power supply with multiphase interleaving and multiple sets of switches in parallel. The hydrogen production power supply includes N parallel step-down converters. The system includes: a main control module and N control modules.

[0045] Each of the control modules is connected to one of the buck converters, and each of the control modules is also connected to the main control module;

[0046] The control module is used to detect the switching state of the switching transistors in the buck converter and the voltage value of the diodes in the buck converter; based on the switching state and the voltage value, it detects whether the buck converter has malfunctioned and the type of malfunction; and when it detects that the buck converter is working normally, it sends a first control signal to the main control module.

[0047] The main control module is used to count the number M of the first control signals received, M≤N; calculate the operating current command and interleaved conduction angle of each buck converter based on the number M of the first control signals received; and send the operating current command and the interleaved conduction angle to the control module that outputs the first control signal.

[0048] The M control modules are also used to form a new daisy-chain communication structure based on the operating current command and the staggered conduction angle to drive the buck converter to work.

[0049] The aforementioned fault diagnosis and automatic fault-tolerant system, by setting a control module on each buck converter, diagnoses whether the buck converter has malfunctioned based on the collected switching status of the switching transistors and the voltage values ​​of the diodes. The main control module counts the number of buck converters that are operating normally and, based on the number of normally operating buck converters, redistributes the operating current and interleaved conduction angle of the buck converters according to the daisy-chain communication structure. This achieves fault isolation and automatic fault tolerance of the hydrogen production power supply. In other words, through the coordinated cooperation of fault monitoring technology and automatic fault-tolerant control technology, faults can be quickly located and isolated, and the DC current and delay conduction angle increments can be automatically updated to achieve safe, reliable, and automatic interleaved operation of the hydrogen production power supply, ensuring that the output ripple of the hydrogen production power supply is always minimized.

[0050] Please see Figure 1 In one embodiment, a fault diagnosis and automatic fault tolerance system 10 is applied to a hydrogen production power supply 300 with multiphase interleaving and multiple sets of switches in parallel. The hydrogen production power supply 300 includes N parallel step-down converters 310. The system includes a main control module 100 and N control modules 200.

[0051] Each of the control modules is connected to one of the buck converters, and each of the control modules is also connected to the main control module;

[0052] The control module is used to detect the switching state of the switching transistors in the buck converter and the voltage value of the diodes in the buck converter; based on the switching state and the voltage value, it detects whether the buck converter has malfunctioned and the type of malfunction; and when it detects that the buck converter is working normally, it sends a first control signal to the main control module.

[0053] The main control module is used to count the number M of the first control signals received, M≤N; calculate the operating current command and interleaved conduction angle of each buck converter based on the number M of the first control signals received; and send the operating current command and the interleaved conduction angle to the control module that outputs the first control signal.

[0054] The M control modules are also used to form a new daisy-chain communication structure based on the operating current command and the staggered conduction angle to drive the buck converter to work.

[0055] Specifically, the circuit diagram of a hydrogen production power supply with multiphase interleaving and multiple sets of switches in parallel is as follows: Figure 3 As shown, the buck converter, also known as a BUCK converter, is used in hydrogen production power supplies composed of several BUCK converters connected in parallel. Considering the limitations of the control module's output I / O ports and IGBT module junction temperatures, and to accommodate the 1200Nm... 3 In a / h alkaline electrolyzer, several IGBT modules need to be connected in parallel in each branch of the BUCK converter. Each step-down converter includes multiple switching transistors and diodes. The switching terminals of the multiple switching transistors are connected in parallel sequentially, and the multiple diodes are connected in parallel sequentially. Each switching transistor is connected to one diode to form multiple sets of parallel switches. It should be noted that this invention is also applicable to hydrogen production power supplies with multiphase interleaving and a set of parallel switches, and its specific circuit diagram is as follows. Figure 2 As shown.

[0056] Specifically, the control module is connected to the buck converter, that is, the output terminal of the control module is connected to the control terminal of the switching transistor in the buck converter to control the operating current and alternating conduction angle of the buck converter.

[0057] Specifically, the main control module only sends operating current commands and staggered conduction angles to the control module connected to the normally operating step-down converter, so as to achieve automatic staggered operation after the step-down converter of the hydrogen production power supply fails.

[0058] Specifically, the M control modules are further configured to form a new daisy-chain communication structure based on the operating current command and the staggered conduction angle. This involves defining upstream and downstream control modules, designating the (n-1)th control module as the upstream control module of the nth control module, the nth control module as the downstream control module of the (n-1)th control module, and the last control module as the upstream control module of the first control module. The communication architecture of these control modules forms a closed-loop chain, i.e., a daisy-chain communication structure. For example: Figure 6 As shown, the control module connected to the first converter is the upstream control module, the control module connected to the second converter is the downstream control module, and so on. The control module connected to the Nth converter is the upstream control module, and the control module connected to the first converter is the downstream control module.

[0059] The upstream control module provides its own pulse trigger angle to the downstream control module. Each control module obtains its own control signal delay angle signal by adding the pulse trigger angle provided by the upstream control module to the delay angle of each phase provided by the main control module.

[0060] When a control module or critical device in the loop fails, the control link connection is reconstructed using a multiplexer across the faulty phase, re-establishing the closed-loop chain. The upstream control module continues to transmit delay angle signals to the downstream control module, thereby achieving automatic fault tolerance in the hydrogen production power supply. For example, ... Figure 6 and Figure 7 As shown, if the second control module or the second key equipment fails, the first control module will cross the faulty second control module and connect with the third module to transmit the delay angle signal, thereby realizing a new daisy-chain communication structure.

[0061] The aforementioned fault diagnosis and automatic fault-tolerant system, by setting a control module on each buck converter, diagnoses whether the buck converter has malfunctioned based on the collected switching status of the switching transistors and the voltage values ​​of the diodes. The main control module counts the number of buck converters that are operating normally and, based on the number of normally operating buck converters, redistributes the operating current and interleaved conduction angle of the buck converters according to the daisy-chain communication structure. This achieves fault isolation and automatic fault tolerance of the hydrogen production power supply. In other words, through the coordinated cooperation of fault monitoring technology and automatic fault-tolerant control technology, faults can be quickly located and isolated, and the DC current and delay conduction angle increments can be automatically updated to achieve safe, reliable, and automatic interleaved operation of the hydrogen production power supply, ensuring that the output ripple of the hydrogen production power supply is always minimized.

[0062] In one embodiment, the control module detects whether the buck converter has malfunctioned and the type of malfunction based on the switch state and the voltage value as follows:

[0063] When s(t) = 0 and U is detected D (t)>U Dth1 If the capacitor of the buck converter is short-circuited, then it is determined that U is faulty. Dth1 =U do +i L *r short s(t) = 0 indicates that the switch is in the off state, U D (t) represents the diode voltage, U Dth1 i is the voltage threshold of the diode. L For inductor current, r short This is the short-circuit impedance of the capacitor;

[0064] When s(t) = 0 and U is detected D If (t) > 0, then the switching transistor of the buck converter is determined to have a short circuit fault;

[0065] When s(t) = 1 and U is detected D When s(t) > 0, it is determined that all the switching transistors of the buck converter have an open circuit fault, where s(t) = 0 indicates that the switching transistors are in the off state;

[0066] When s(t) = 1 and U is detected th2 D If (t) < 0, then the diode of the buck converter is determined to have a short-circuit fault, where U th2 =-U in +r s *i s,max U in Input voltage;

[0067] When s(t) = 0 and U D (t)>U th3 AndU th3 =4U f,max If so, it is determined that all diodes in the buck converter have an open-circuit fault, where U f,max Maximum instantaneous pre-voltage of the diode.

[0068] Specifically, in capacitor short-circuit fault diagnosis, a capacitor short circuit occurs when an inter-electrode short circuit occurs on the DC load side. Energy is injected into the fault point by the system, charging the inductor and causing a drop in the DC line voltage. When the IGBT closes (s(t) = 1), the power supply charges the inductor, and the current in the faulty branch increases. The KVL equation for the faulty circuit is:

[0069] U​in =U s (t) + U L (t) + U oshort (t)(1)

[0070] U in =U so +r s i L (t)+Ldi L / dt+i L r short (2)

[0071] In equation (1), U in U is the input voltage. s (t) represents the IGBT module voltage, U L (t) represents the inductor voltage, U oshort (t); In equation (2), U so For the built-in voltage of the IGBT module, r s Where L is the internal resistance of the IGBT, and i is the inductance. L For inductor current, r short This is the short-circuit impedance of the capacitor.

[0072] When the IGBT is turned off, i.e., s(t) = 0, the inductor stops charging and discharges through the diode, while the inductor current remains essentially unchanged.

[0073] U D (t)=U L (t)+U oshort (t)=Ldi L / dt+i L r short (3)

[0074] U D (t)=U do +i L r short (4)

[0075] After several cycles, when s(t) = 0, the branch current reaches the inductor current limit, that is, twice the maximum normal operating current, at which point the diode U... D(t) Reaching the maximum positive value. Setting the inductor current overcurrent threshold i. Lover Set the diode voltage threshold to U, which corresponds to the maximum current at the diode terminal voltage. Dth1 , then U Dth1 =U do +i Lover r short When s(t) = 0 and U is detected D (t)>U Dth1When the output capacitor experiences a short circuit fault, the branch in this article refers to a buck converter.

[0076] IGBT module short-circuit fault detection: When a short-circuit fault occurs in an IGBT module on a branch, the entire branch will be short-circuited. If the fault occurs at the moment the IGBT is turned off, i.e., when s(t) = 0, the voltage across the diode is:

[0077] U D (t) = -U in +U s (t) < 0 (5)

[0078] When the IGBT is operating normally and S(t)=0, the voltage across the diode is: U D (t)=U do +r d i L (t)>0, therefore when s(t)=0 and U is detected D When (t) > 0, the IGBT parallel module of this branch experiences a short circuit fault.

[0079] When an IGBT experiences an open-circuit fault in some IGBTs on a branch, the system can still operate normally without affecting output voltage, current, or power quality. However, the normally operating IGBT switches need to redistribute the branch current, increasing IGBT module losses and consequently raising junction temperature. Normally, the maximum junction temperature of an IGBT is limited to 150℃. To ensure current balance in parallel IGBT modules and maintain an operating temperature below the maximum junction temperature, it's necessary to measure the IGBT module junction temperature. However, due to the packaged structure of the IGBT module, the internal junction temperature cannot be measured. Considering that the IGBT junction temperature is related to its thermistor, the junction temperature can be indirectly obtained by measuring the thermistor. A thermistor Z is set at 130℃. th130 The open-circuit threshold is the thermistor Z of the normally operating IGBT module. thIGBTi >Z th130 When this occurs, the IGBT module in that branch is diagnosed as open-circuited. Considering that the faulty IGBT shares a heatsink with the normally operating IGBTs, temperature will transfer between the devices, and the thermistor of the faulty phase will also change. However, since no current flows through it, the thermistor change is small, and the corresponding junction temperature is small; therefore, this is not used as a criterion for diagnosing an open-circuit IGBT. 130℃ was chosen to provide a certain margin for the IGBT module, to avoid overheating and breakdown of the normally operating IGBT module under other fault conditions.

[0080] When all IGBT modules on a branch experience an open-circuit fault, the diodes remain in the conducting state when s(t) = 1, i.e., U D (t)=U d0 +i L rd >0, under normal circumstances, the diode withstands reverse voltage. Therefore, when s(t) = 1 and U is detected... D When (t) > 0, it can be determined that all IGBTs on a certain branch are open.

[0081] Diode short-circuit fault detection is similar to IGBT module short-circuit fault detection. When a diode in a branch experiences a short-circuit fault, all diodes in the entire branch will be short-circuited. If the fault occurs at the IGBT turn-on moment, i.e., when S(t)=1, the reverse voltage across the diode will be less than the reverse voltage during normal operation, i.e., U... th2 D (t)<0, where U th2 =-U in +r s i s,max That is, S(t)=1 and U is detected. th2 D If (t) < 0, it can be determined that the diode is short-circuited.

[0082] Diode open-circuit fault detection is similar to IGBT module open-circuit fault detection. When some diodes on a branch experience open-circuit faults, the system can still operate normally, and the output voltage, current, and power quality are unaffected. However, the normally operating diodes need to redistribute the branch current, increasing diode module losses and consequently raising the junction temperature. Similar to IGBT partial open-circuit fault monitoring methods, the junction temperature of the diode is indirectly obtained by measuring its thermistor. A thermistor Z is set at 130℃. Dth130 The open-circuit threshold is the value of the diode thermistor Z during normal operation. thdiodei >Z Dth130 At that time, the diagnosis was that some IGBT modules in that branch were open-circuited. 130℃ was chosen to provide a certain margin for the diodes, to avoid overheating and breakdown of normal diodes under other fault conditions. Similar to the open-circuit fault of some IGBT modules, the change in thermistor resistance of the faulty phase was not selected as the criterion for judging the open-circuit fault of some diodes.

[0083] When all diodes on a branch circuit experience an open-circuit fault, the inductor current cannot release energy through the diodes, resulting in a large voltage being applied across them. Let U be the voltage across the diodes. th3 The open-circuit criterion for all IGBT modules is when S(t)=0 and U is detected. D (t)>U th3 AndU th3 =4U f,max U f,max Maximum instantaneous pre-voltage of the diode.

[0084] ​​It is important to note that traditional methods for diagnosing critical equipment faults typically involve identifying the sampling information required for the specific IGBT modules. In such cases, to achieve current sharing, each branch of the parallel IGBT modules needs current and temperature sampling to monitor for overcurrent and overheating. However, this method requires numerous measuring devices, is costly, and can only monitor IGBT modules. This embodiment uses diode terminal voltage information and the rate of change of the semiconductor device's thermistor resistance as the basis for judgment to achieve online fault diagnosis of critical equipment. It clarifies the fault types of critical equipment in the hydrogen production power supply, including output capacitor short circuits, IGBT module short circuits and open circuits, and diode short circuits and open circuits. Short-circuit characteristic analysis is performed on key components, summarizing their relationship with diode terminal voltage and semiconductor device thermistor resistance.

[0085] In one embodiment, the control module is further configured to detect the resistance Z of the thermistor in the buck converter. thIGBTi When Z thIGBTi >Z th130 If the diode of the buck converter is open-circuit faulted, then Z is determined to be faulty. th130 This is the open-circuit threshold of the thermistor at 130℃.

[0086] When an IGBT experiences an open-circuit fault in some IGBTs on a branch, the system can still operate normally without affecting output voltage, current, or power quality. However, the normally operating IGBT switches need to redistribute the branch current, increasing IGBT module losses and consequently raising junction temperature. Normally, the maximum junction temperature of an IGBT is limited to 150℃. To ensure current balance in parallel IGBT modules and maintain an operating temperature below the maximum junction temperature, it's necessary to measure the IGBT module junction temperature. However, due to the packaged structure of the IGBT module, the internal junction temperature cannot be measured. Considering that the IGBT junction temperature is related to its thermistor, the junction temperature can be indirectly obtained by measuring the thermistor. A thermistor Z is set at 130℃. th130 The open-circuit threshold is the thermistor Z of the normally operating IGBT module. thIGBTi >Z th130 When this occurs, the IGBT module in that branch is diagnosed as open-circuited. Considering that the faulty IGBT shares a heatsink with the normally operating IGBTs, temperature will transfer between the devices, and the thermistor of the faulty phase will also change. However, since no current flows through it, the thermistor change is small, and the corresponding junction temperature is small; therefore, this is not used as a criterion for diagnosing an open-circuit IGBT. 130℃ was chosen to provide a certain margin for the IGBT module, to avoid overheating and breakdown of the normally operating IGBT module under other fault conditions.

[0087] The above embodiments specifically illustrate the principle of how the control module detects whether a buck converter has malfunctioned. Fault detection of the buck converter can be achieved simply by connecting the control module's detection pins to the corresponding detection points of the buck converter and adding a suitable logic judgment module. In one embodiment, the logic judgment principle by which the control module detects whether the buck transformer has malfunctioned based on the switch state and the voltage value is as follows: Figure 4 As shown, where s(t) and U D (t), Z thIGBT and Z thdiodei For the detection end, U Dth1 U th2 U th3 and Z Dth130 Reference source, Fc short 、Fs icaprt F sicall FD is FD icall and FD icpart This is the fault signal output terminal. By adopting... Figure 4 The logic circuit shown can be used to detect faults in buck converters.

[0088] In one embodiment, each of the control modules has its own communication unit, which is used to realize signal transmission between the control modules, so that the M control modules form a new daisy-chain communication structure according to the received operating current command and the staggered conduction angle.

[0089] Specifically, this application achieves automatic phase shifting of hydrogen production power through a daisy-chain communication structure. In one embodiment, the communication unit is an optical fiber communication unit. Specifically, a communication architecture is set up, with each control module having its own optical fiber communication, enabling signal transmission between control modules. Upstream and downstream control modules are defined. For example, if the control module of the first converter is the upstream control module, then the control module of the second converter is the downstream control module, and so on, with the control module of the Nth converter being the upstream control module and the control module of the first converter being the downstream control module. The communication architecture of each control module forms a closed-loop chain, i.e., the so-called daisy-chain communication structure.

[0090] In one embodiment, the control module sends a second control signal to the main control module when a fault is detected in the buck converter, wherein the first control signal is a low-level signal and the second control signal is a high-level signal. In another embodiment, the main control module includes N input interfaces and N output interfaces. Each input interface is connected to an output terminal of a control module, and each output interface is connected to an input terminal of a control module; that is, each input interface corresponds to a control module, and each output interface corresponds to a control module. Thus, the main control module can determine which buck converter has failed based on the control signals received from the input interfaces, count the number of normally functioning buck converters, and send the calculated operating current command and interleaved conduction angle to the corresponding control module, achieving automatic fault tolerance.

[0091] Please see Figure 4 and Figure 5 In one embodiment, each of the control modules includes an input / output switch, a NOR gate, a logic judgment unit, a control unit, and a resistor.

[0092] The input terminal of the logic judgment unit is connected to a buck converter. The output terminal of the logic judgment unit is connected to the first input terminal of the NOR gate. The second input terminal of the NOR gate is connected to the power supply through a resistor. The second terminal of the NOR gate is also grounded through the input / output switch. The output terminal of the NOR gate is connected to the input terminal of the main control module. The output terminal of the main control module is connected to the input terminal of the control unit. The control unit is used to drive the buck converter to work. The logic judgment unit is used to determine whether the buck converter has malfunctioned.

[0093] Specifically, Figure 5 The protection signal in the logic judgment unit is the detection signal output by the logic judgment unit. Each control module is equipped with an on / off switch. Before the control module is put into use, its working signal is a high-level signal, and the drive signal of the control unit cannot be sent to the drive circuit. When the on / off switch is closed, the module's working signal is pulled to a low-level signal. During normal operation, the module's protection signal is a low-level signal, and it remains a low-level signal after passing through an OR AND gate. The main control module detects that the control module's working signal is a low-level signal and determines that the control module is put into operation. The main control module can determine the number of interleaved parallel phases involved in the operation by detecting the number M of low-level signals. Then, M is equally divided into the current command I calculated by the main control module based on voltage-power droop control. ref At the same time, the delay angle increment required for the interleaved conduction of each control module is updated to δ=360 / M.

[0094] Specifically, the circuit diagram of the logic judgment unit is as follows: Figure 4 As shown, where Fc short The capacitor is short-circuited if and only if s(t) = 0 and U D (t)>U Dth1 U Dth1 =U do +i Lover r short ;Fs icpart This indicates that an open-circuit fault has occurred in some IGBT modules of a certain branch circuit. The judgment criterion is Z. thIGBTi >Z th130 ;Fs icall This indicates that all IGBT modules in a certain branch have an open-circuit fault, and the detection criteria are S(t)=1 and U D (t)>0;Fs is This indicates that a short-circuit fault has occurred in an IGBT on a certain branch, and the judgment is based on s(t)=0 and U D (t)>0;FD is This indicates that a diode on a certain path has a short-circuit fault, and the judgment is based on S(t)=1 and U th2 D (t)<0, U th2 =-U in +r s i s,max ;FD icall This indicates that all diodes on a certain path have an open-circuit fault, and the judgment is based on s(t)=0 and U D (t)>U th3 U th3 =4U f,max ;FD icpart This indicates that an open-circuit fault has occurred in the diode section of a certain path, and the judgment is based on Z. thdiodei >Z Dth130 In this way, the fault type of key equipment in the hydrogen production power supply can be accurately identified, and the fault signal can be sent to the main control module.

[0095] Please see Figure 3 In one embodiment, each of the buck converters includes a plurality of switching transistors, a plurality of diodes, and an inductor. The number of switching transistors is equal to the number of diodes. The first terminal of each switching transistor is connected to the positive terminal of the input power supply. The second terminal of each switching transistor is connected to the negative terminals of the plurality of diodes. The negative terminal of each diode is connected to the negative terminal of the input power supply. The second terminal of the second terminal of the switching transistor is also connected to the first terminal of the inductor. The second terminals of each inductor are interconnected.

[0096] ​In one embodiment, the switching transistor is an IGBT (Insulated Gate Bipolar Transistor).

[0097] In one embodiment, the number of buck converters is 9, and the number of switching transistors and diodes in each buck converter is 6. Specifically, for the hydrogen production power supply structure diagram of 9-phase interleaving and 6 groups of switches in parallel supporting a 1200 Nm 3 / h large-capacity alkaline electrolyzer, the IGBT module is selected as the Infineon IFF450F17ME4 model, the inductance of each phase is 175 μH, and the total output capacitance is 2.1 mF. To ensure the safe, reliable, and efficient operation of the hydrogen production power supply, fault diagnosis and automatic fault tolerance technologies are essential. The fault diagnosis and automatic fault tolerance technologies include fault diagnosis of key devices of the hydrogen production power supply, automatic identification of working phases of the hydrogen production power supply and current redistribution, and automatic phase shift of the hydrogen production power supply based on daisy chain communication.

[0098] Please refer to Figure 1 、 3 、4, 5, 6, and 8. In one embodiment, the fault diagnosis of key devices of the hydrogen production power supply is achieved through the following steps:

[0099] ①. Define the sampling information required for fault diagnosis of key equipment, and use the diode terminal voltage information and the change rate of the semiconductor device thermistor as the judgment basis to achieve online fault diagnosis of key equipment.

[0100] ②. Define the fault types of key equipment of the hydrogen production power supply, including output capacitor short circuit, IGBT module short circuit and open circuit, diode short circuit and open circuit.

[0101] ③. Conduct a short-circuit characteristic analysis of key devices, and summarize the relationship between them and the diode terminal voltage and the semiconductor device thermistor.

[0102] The automatic identification of working phases of the hydrogen production power supply and current redistribution technology is achieved through the following steps:

[0103] Set the main control module, and the main control module selects the FPGA, which needs to achieve three functions during operation:

[0104] ①. Send working signals to each control module;

[0105] ②. Detect the number of low-level signal outputs of the I / O ports of each control module;

[0106] ③. Send working current instructions and an interleaved conduction angle of 360° / M to each module.

[0107] Each branch control module is equipped with a cut-in and cut-out switch. When this branch is not in use, the detected working signal is at a high level. When the cut-in and cut-out switch of this branch closes, the working signal is pulled to a low level.

[0108] Collect the working signal of the protection circuit. During normal operation, the working level signal of the protection circuit is a low-level signal. After passing through an OR gate with the working level, the signal is transmitted to the set main control module.

[0109] The main control module FPGA automatically updates the number M of converters participating in control by detecting the working level signals of all branches. At the same time, it updates the branch current command Iref / M and the delay conduction angle increment 360° / M.

[0110] The automatic phase shift technology of the hydrogen production power supply based on daisy-chain communication can be realized through the following steps:

[0111] ①. Set up the communication architecture. Each control module has its own fiber optic communication, which can realize signal transmission between control modules, and define the upstream control module and the downstream control module.

[0112] ②. The upstream controller provides its own pulse trigger angle to the downstream controller. Each controller adds the angle provided by the upstream controller to the delay angle of each phase provided by the main controller to obtain the delay angle signal of its own control signal.

[0113] ③. When a controller or a key device in a certain path of the loop fails, cross the faulty phase, use a multiplexer to reconstruct the control link connection, and re-implement the closed-loop chain. The upstream controller continues to transmit the delay angle signal to the downstream controller.

[0114] The following are the specific applications of the fault diagnosis and automatic fault tolerance system:

[0115] For the hydrogen production power supply structure diagram of 9-phase interleaving and 6 groups of switches in parallel supporting a 1200 Nm3 / h large-capacity alkaline electrolyzer, the IGBT module is selected as the Infineon IFF450F17ME4 model, the inductance of each phase is 175 μH, and the total output capacitance is 2.1 mF. In order to ensure the safe, reliable and efficient operation of the hydrogen production power supply, fault diagnosis and automatic fault tolerance technology are essential. The fault diagnosis and automatic fault tolerance technology include the fault diagnosis of key devices of the hydrogen production power supply, the automatic identification of working phases of the hydrogen production power supply and current redistribution, and the automatic phase shift of the hydrogen production power supply based on daisy-chain communication.

[0116] Among them, fault diagnosis is the basis for ensuring the safe and stable operation of the system. Figure 4 It is the logic schematic diagram for judging the faults of key devices of the hydrogen production power supply. Among them, the capacitor is the device most prone to failure in the system, which restricts the service life of the whole device. When the IGBT is in the off state, U is detected. D(t)>U Dth1 U Dth1 =U do +i Lover r short When this happens, it means that a short circuit fault has occurred in the output capacitor, and the fault alarm signal Fc is triggered. short .

[0117] Furthermore, semiconductor device failures account for 30% to 35% of all converter failures, typically categorized as short-circuit and open-circuit faults. These types of failures can have severe consequences for the system and require timely diagnosis and isolation.

[0118] The hydrogen production power source contains 54 IGBTs and 54 diodes, with 6 IGBT modules connected in parallel as one group and 6 diode modules connected in parallel as another group, for a total of 9 groups. When s(t) = 0, if U is detected... D If (t)>0, it means that an IGBT short-circuit fault has occurred in this branch. This fault may be caused by a short circuit of an IGBT in this branch, or it may be caused by a short circuit of all IGBTs in this branch. The fault signal is Fs. is When some IGBTs in a branch experience an open-circuit fault, theoretically it should not affect the normal operation of the converter. However, the normally operating IGBT switches need to redistribute the branch current they bear. If the measured thermistor value is greater than Z... th130 If this occurs, the diagnosis is an open-circuit fault in the IGBT modules of that branch, and the fault signal is Fs. icaprt When S(t)=1, if U is detected D (t)>0 means that all IGBT modules in a certain branch have an open-circuit fault, and the fault signal is F. sicall When s(t)=0, if U is detected th2 D If (t) < 0, it means that a short circuit fault has occurred in a branch diode, similar to an IGBT short circuit fault. It can cause a short circuit in one diode or all diodes to short circuit. The fault signal is FD. is If U is detected when s(t)=0 D (t)>U th3 This means that all diodes on a certain branch have an open-circuit fault, and the fault signal is FD. icall Similar to an IGBT partial open-circuit fault, when Z is detected... thdiodei >Z Dth130 The diode experienced an open circuit in some components, and the fault signal was FD. icpart .

[0119] ​After a fault is detected, the faulty branch is isolated by a protective switch connected in series with the branch, and the 9-phase interleaved converter is reconfigured. The switching signals of each controller are detected; control modules not in operation have a high-level signal, while those in operation have a low-level signal. The main control module detects the number M of low-level signals. Assuming only one branch is faulty, M=8, thus determining that the number of interleaved parallel phases involved is 8. The current command I, calculated by the main control module based on voltage-power droop control, is then divided into 8 equal parts. ref / 8, and at the same time update the delay angle increment δ=360 / 8 required for the interleaved conduction of each control module.

[0120] In this embodiment, the communication structure adopts a daisy-chain connection. The first branch is the upstream branch, and its control module is the upstream control module. The second branch is the downstream branch of the first branch, and its control module is the downstream control module of the first branch control module. And so on, the eighth branch is the upstream branch of the ninth branch, the control module of the eighth branch is the upstream control module of the ninth branch, and the ninth branch is the downstream control module of the eighth branch. In order to ensure the reliability of the communication system, it needs to form a closed-loop system, which means that the ninth branch is the upstream branch of the first branch, the control module of the ninth branch is the upstream control module of the first branch control module, and the first branch is the downstream control module of the ninth branch. If the seventh branch fails, the multiplexer can reconnect the sixth and eighth branches to form a closed loop. Each control module then transmits its own conduction angle to the downstream control module. The downstream control module obtains its own conduction angle information by superimposing the delayed conduction angle increment issued by the main control and the conduction angle of the upstream control, and transmits it to its downstream control module. And so on, finally realizing automatic switching after the hydrogen production power supply fails. In this embodiment, the branch refers to the buck converter.

[0121] Based on the proposed fault diagnosis and automatic fault-tolerant control technology, the hydrogen production power supply control module can detect system fault types within several cycles. Specifically, the detection of IGBT short circuits and all open circuit faults, as well as diode short circuits and all open circuit faults, can be achieved within one cycle, demonstrating rapid detection. After isolating the fault through the protection switch, system reconfiguration and automatic interleaving control are required to ensure minimal system output ripple.

[0122] In one embodiment, such as Figure 9 As shown, a fault diagnosis and automatic fault tolerance method is provided, applied to the fault diagnosis and automatic fault tolerance system described in any of the above embodiments. The method includes:

[0123] Step 710: Obtain the switching state of the switching transistor in the buck converter and detect the voltage value of the diode in the buck converter;

[0124] Step 720: Based on the switch status and the voltage value, detect whether the buck converter has a fault and the type of fault.

[0125] Step 730: Count the number M of the buck converters that are working normally;

[0126] Step 740: Based on the number M of the buck converters operating normally, calculate the operating current command and interleaved conduction angle of each buck converter.

[0127] Step 750: The operating current command and the interleaved conduction angle are sent to M of the control modules, so that the control modules form a new daisy-chain communication structure according to the operating current command and the interleaved conduction angle, and drive the buck converter to work.

[0128] The aforementioned fault diagnosis and automatic fault tolerance method involves setting up a control module on each buck converter. This control module diagnoses whether a buck converter has malfunctioned based on the collected switching states of the switching transistors and the voltage values ​​of the diodes. The main control module counts the number of buck converters operating normally and, based on a daisy-chain communication structure, redistributes the operating current and interleaved conduction angles of the buck converters to achieve fault isolation and automatic fault tolerance of the hydrogen production power supply. In other words, through the coordinated operation of fault monitoring technology and automatic fault tolerance control technology, faults can be quickly located and isolated, and the DC current and delayed conduction angle increments can be automatically updated to ensure safe, reliable, and automatic interleaved operation of the hydrogen production power supply, ensuring that the output ripple of the hydrogen production power supply is always minimized.

[0129] In one embodiment, the principle for detecting whether the buck converter has a fault and the type of fault is as follows:

[0130] When s(t) = 0 and U is detected D (t)>U Dth1 If the capacitor of the buck converter is short-circuited, then it is determined that U is faulty. Dth1 =U do +i L *r short s(t) = 0 indicates that the switch is in the off state, U D (t) represents the diode voltage, U Dth1 i is the voltage threshold of the diode. L For inductor current, r short This is the short-circuit impedance of the capacitor;

[0131] When s(t) = 0 and U is detected D If (t) > 0, then the switching transistor of the buck converter is determined to have a short circuit fault;

[0132] When s(t) = 1 and U is detected D When s(t) > 0, it is determined that all the switching transistors of the buck converter have an open circuit fault, where s(t) = 0 indicates that the switching transistors are in the off state;

[0133] When s(t) = 1 and U is detected th2 D If (t) < 0, then the diode of the buck converter is determined to have a short-circuit fault, where U th2 =-U in +r s *i s,max U in Input voltage;

[0134] When s(t) = 0 and U D (t)>U th3 AndU th3 =4U f,max If so, it is determined that all diodes in the buck converter have an open-circuit fault, where U f,max Maximum instantaneous pre-voltage of the diode.

[0135] When Z thIGBTi >Z th130 If the diode of the buck converter is open-circuit faulted, then Z is determined to be faulty. th130 This is the open-circuit threshold of the thermistor at 130℃.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.​

Claims

1. A fault diagnosis and automatic fault-tolerant system, applied to a hydrogen production power supply with multiphase interleaving and multiple sets of switches connected in parallel, wherein the hydrogen production power supply includes N buck converters connected in parallel, characterized in that, The system includes: a main control module and N control modules; Each of the control modules is connected to one of the buck converters, and each of the control modules is also connected to the main control module; wherein, the detection pins of the control module are connected to the corresponding detection points of the buck converter; The control module is used to detect the switching state of the switching transistors in the buck converter and the voltage value of the diodes in the buck converter; based on the switching state and the voltage value, it detects whether the buck converter has malfunctioned and the type of malfunction; and when it detects that the buck converter is working normally, it sends a first control signal to the main control module. The main control module is used to count the number M of the first control signals received, where M ≤ N; and to calculate the operating current command and interleaved conduction angle of each buck converter based on the number M of the first control signals received, wherein the operating current command is obtained by dividing the current command into M equal parts and calculating it according to voltage-power droop control by the main control module; and to send the operating current command and the interleaved conduction angle to the control module that outputs the first control signal. The M control modules are also used to form a new daisy-chain communication structure based on the operating current command and the staggered conduction angle to drive the buck converter to work. The control module is used to detect whether the buck converter has malfunctioned and the type of malfunction based on the switch state and the voltage value. The principle is as follows: When s(t) = 0 and U is detected D (t)>U Dth1 If the capacitor of the buck converter is short-circuited, then it is determined that U is faulty. Dth1 =U do +i Lover *r short s(t) = 0 indicates that the switch is in the off state, U D (t) represents the diode voltage, U Dth1 i is the voltage threshold of the diode. Lover r is the inductor current overcurrent threshold. short U is the short-circuit impedance of the capacitor. do Inductor voltage; When s(t) = 0 and U is detected D If (t) > 0, then the switching transistor of the buck converter is determined to have a short circuit fault; When s(t) = 1 and U is detected D When s(t) > 0, it is determined that all the switches of the buck converter have an open circuit fault, where s(t) = 1 indicates that the switch is in the closed state; When s(t) = 1 and U is detected th2 D If (t) < 0, then the diode of the buck converter is determined to have a short-circuit fault, where U th2 =-U in +r s *i s,max U in For the input voltage, r s Indicates the internal resistance of the switching transistor;​ When s(t) = 0 and U D (t)>U th3 AndU th3 =4U f,max If so, it is determined that all diodes in the buck converter have an open-circuit fault, where U f,max Maximum instantaneous pre-voltage of the diode; The control module is also used to detect the resistance Z of the thermistor in the buck converter. thIGBTi When Z thIGBTi >Z th130 If the diode of the buck converter is open-circuit faulted, then Z is determined to be faulty. th130 This is the open-circuit threshold of the thermistor at 130℃.

2. The fault diagnosis and automatic fault-tolerance system according to claim 1, characterized in that, Each of the control modules has its own communication unit, which is used to realize signal transmission between the control modules, so that the M control modules form a new daisy-chain communication structure according to the received operating current command and the staggered conduction angle.

3. The fault diagnosis and automatic fault-tolerance system according to claim 1, characterized in that, The control module is used to send a second control signal to the main control module when a fault is detected in the buck converter, wherein the first control signal is a low-level signal and the second control signal is a high-level signal.

4. The fault diagnosis and automatic fault-tolerance system according to claim 3, characterized in that, Each of the control modules includes an input / output switch, a NOR gate, a logic judgment unit, a control unit, and a resistor; The input terminal of the logic judgment unit is connected to a buck converter. The output terminal of the logic judgment unit is connected to the first input terminal of the NOR gate. The second input terminal of the NOR gate is connected to the power supply through a resistor. The second terminal of the NOR gate is also grounded through the input / output switch. The output terminal of the NOR gate is connected to the input terminal of the main control module. The output terminal of the main control module is connected to the input terminal of the control unit. The control unit is used to drive the buck converter to work. The logic judgment unit is used to determine whether the buck converter has malfunctioned.

5. The fault diagnosis and automatic fault-tolerant system according to any one of claims 1 to 4, characterized in that, Each of the buck converters includes multiple switching transistors, multiple diodes, and inductors. The number of switching transistors is equal to the number of diodes. The first terminal of each switching transistor is connected to the positive terminal of the input power supply. The second terminal of each switching transistor is connected to the negative terminals of the multiple diodes. The negative terminal of each diode is connected to the negative terminal of the input power supply. The second terminal of the second terminal of the switching transistor is also connected to the first terminal of the inductor. The second terminals of each inductor are interconnected.

6. The fault diagnosis and automatic fault-tolerance system according to claim 5, characterized in that, The switching transistor is an IGBT.

7. The fault diagnosis and automatic fault-tolerance system according to claim 5, characterized in that, There are nine buck converters, and each buck converter contains six switching transistors and six diodes.

8. A fault diagnosis and automatic fault tolerance method, applied to the fault diagnosis and automatic fault tolerance system according to any one of claims 1 to 7, characterized in that, include: The switching state of the switching transistors in the buck converter is obtained, and the voltage value of the diodes in the buck converter is detected. Based on the switch status and the voltage value, detect whether the buck converter has malfunctioned and the type of malfunction; The number M of the buck converters that are operating normally; Based on the number M of the buck converters in normal operation, the operating current command and interleaved conduction angle of each buck converter are calculated. The operating current command and the interleaved conduction angle are sent to M control modules, so that the control modules form a new daisy-chain communication structure according to the operating current command and the interleaved conduction angle, and drive the buck converter to work.

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