LLC resonant converter fault diagnosis method, device, equipment, medium and program product

Abstract

The present invention discloses a fault diagnosis method, device, equipment, medium and program product for an LLC resonant converter. The method comprises: performing an open-circuit fault analysis on the LLC resonant converter, and generating a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result; in response to an open-circuit fault occurring in the LLC resonant converter, collecting drain-source voltage parameters of switch tubes of each bridge arm in the LLC resonant converter, determining a target drain-source voltage value of each switch tube based on the drain-source voltage parameters of the switch tube, and performing fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value; because the present invention constructs an accurate fault diagnosis strategy through open-circuit fault analysis, and analyzes the drain-source voltage parameters of the switch tube during the open-circuit fault in combination with the fault diagnosis strategy, efficient fault diagnosis is achieved, thereby timely discovering and locating the fault, thereby effectively improving the reliability and stability of the LLC resonant converter.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and in particular to a LLC resonant converter fault diagnosis method, device, equipment, medium and program product. Background Art

[0002] As an advanced power electronic device, variable frequency controlled LLC resonant converter has been widely used in various power supply systems in recent years. Its high efficiency, low electromagnetic interference (EMI) and wide input and output range make it particularly suitable for occasions with high requirements on power supply performance, such as data centers, new energy power generation systems and electric vehicle charging stations.

[0003] However, in practical applications, the open circuit fault of the switching device is a major problem faced by the variable frequency controlled LLC resonant converter. This type of fault may be caused by a variety of reasons, including but not limited to physical damage, component aging, environmental factors, and malfunction of the protection circuit. According to statistics, among all the faults of the variable frequency controlled LLC resonant converter, the open circuit fault of the switching device accounts for a relatively high proportion, posing a serious threat to the stability and reliability of the system. Therefore, it is of great significance to diagnose the open circuit fault of the switching device to ensure the normal operation of the variable frequency controlled LLC resonant converter. However, in the current fault diagnosis process, due to factors such as circuit parameter fluctuations and measurement errors, there are large errors in the diagnostic analysis, which affects the accuracy of the fault diagnosis and makes it impossible to locate and handle the fault in time. Summary of the invention

[0004] The main purpose of the present invention is to provide an LLC resonant converter fault diagnosis method, device, equipment, medium and program product, aiming to solve the technical problems in the prior art that a large amount of data needs to be processed and calculated, the computational complexity of fault analysis, and the existence of data processing delays, resulting in the inability to timely detect and locate LLC resonant converter faults, which easily causes the fault to expand and lead to system shutdown or damage.

[0005] To achieve the above object, the present invention provides a fault diagnosis method for an LLC resonant converter, wherein the primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, and the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4, and the LLC resonant converter fault diagnosis method includes:

[0006] Performing an open-circuit fault analysis on the LLC resonant converter, and generating a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result, wherein the open-circuit fault analysis result includes a drain-source voltage variation rule of the upper bridge arm on the primary side and / or a drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails, and the fault diagnosis strategy includes locating a bridge arm having a fault in the LLC resonant converter based on the drain-source voltage variation rule;

[0007] In response to an open circuit fault occurring in the LLC resonant converter, collecting drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter;

[0008] Determine a target drain-source voltage value of each switch tube based on the switch tube drain-source voltage parameter, wherein the target drain-source voltage value is the sum of a positive cycle drain-source voltage value and a negative cycle drain-source voltage value of each switch tube;

[0009] Fault diagnosis is performed on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value.

[0010] Optionally, performing an open circuit fault analysis on the LLC resonant converter and generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result includes:

[0011] Determine the conduction state of the test switch tube;

[0012] Performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube, and performing open circuit fault analysis on each switch tube on the primary side;

[0013] A fault diagnosis strategy for the LLC resonant converter is generated based on the open circuit fault analysis result.

[0014] Optionally, the test switch conduction state includes: target switch tubes are simultaneously turned on and the target switch tubes are simultaneously closed, and the target switch tubes include the first upper switch tube T1 and the second lower switch tube T4, or the first lower switch tube T2 and the second upper switch tube T3;

[0015] The step of performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube and performing open circuit fault analysis on each switch tube on the primary side includes:

[0016] Acquire a first drain-source voltage value of a switch tube to be analyzed, wherein the switch tube to be analyzed includes the first lower switch tube T2 and the second lower switch tube T4, or the first upper switch tube T1 and the second upper switch tube T3;

[0017] Controlling the first upper switch tube T1 and the second lower switch tube T4 to be turned on at the same time, and sending a shutdown signal to each switch tube respectively, so as to simulate an open circuit fault of each switch tube respectively;

[0018] In response to each switch tube having a fault, obtaining a second drain-source voltage value of the switch tube to be analyzed;

[0019] After each switch tube fails, the first upper switch tube T1 and the second lower switch tube T4 are controlled to be turned off at the same time, and the first lower switch tube T2 and the second upper switch tube T3 are controlled to be turned on at the same time, so as to obtain a third drain-source voltage value of the switch tube to be analyzed;

[0020] An open circuit fault analysis is performed on each switch tube on the primary side based on the first drain-source voltage value, the second drain-source voltage value, and the third drain-source voltage value.

[0021] Optionally, the performing fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value includes:

[0022] Determine a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4 based on the target drain-source voltage value;

[0023] Determine, based on the fault diagnosis strategy, a fault type that matches a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4;

[0024] The faulty switch tube is located according to the fault type to perform fault diagnosis on the LLC resonant converter.

[0025] Optionally, the fault diagnosis strategy includes drain-source voltage conditions corresponding to each fault type;

[0026] The drain-source voltage condition includes:

[0027] If the first upper switch tube T1 fails, the target drain-source voltage value is:

[0028]

[0029] If the first lower switch tube T2 fails, the target drain-source voltage value is:

[0030]

[0031] If the second upper switch tube T3 fails, the target drain-source voltage value is:

[0032]

[0033] If the second lower switch tube T4 fails, the target drain-source voltage value is:

[0034]

[0035] in, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0036] Optionally, the fault diagnosis strategy further includes a fault error coefficient;

[0037] The drain-source voltage condition also includes:

[0038] If the first upper switch tube T1 fails, the following formula is satisfied:

[0039] ,and

[0040] If the first lower switch tube T2 fails, the following formula is satisfied:

[0041] ,and

[0042] If the second upper switch tube T3 fails, the following formula is satisfied:

[0043] ,and

[0044] If the second lower switch tube T4 fails, the following formula is satisfied:

[0045] ,and

[0046] in, is the fault error coefficient, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0047] In addition, to achieve the above-mentioned object, the present invention further proposes an LLC resonant converter fault diagnosis device, wherein the primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, and the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4, and the LLC resonant converter fault diagnosis device includes:

[0048] an open-circuit fault analysis module, configured to perform an open-circuit fault analysis on the LLC resonant converter, and generate a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result, wherein the open-circuit fault analysis result includes a drain-source voltage variation rule of the upper bridge arm on the primary side and / or a drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails, and the fault diagnosis strategy includes locating a bridge arm having a fault in the LLC resonant converter based on the drain-source voltage variation rule;

[0049] A drain-source voltage acquisition module, configured to acquire drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter in response to an open circuit fault occurring in the LLC resonant converter;

[0050] A drain-source voltage calculation module, used to determine a target drain-source voltage value of each switch tube based on the drain-source voltage parameter of the switch tube, wherein the target drain-source voltage value is the sum of a positive cycle drain-source voltage value and a negative cycle drain-source voltage value of each switch tube;

[0051] A fault diagnosis module is used to perform fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value.

[0052] In addition, to achieve the above-mentioned objectives, the present application also proposes an LLC resonant converter fault diagnosis device, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the LLC resonant converter fault diagnosis method as described above.

[0053] In addition, to achieve the above objectives, the present application also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the LLC resonant converter fault diagnosis method as described above are implemented.

[0054] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the LLC resonant converter fault diagnosis method as described above are implemented.

[0055] The present invention performs an open-circuit fault analysis on an LLC resonant converter, generates a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result, collects drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter in response to an open-circuit fault in the LLC resonant converter, determines a target drain-source voltage value of each switch tube based on the drain-source voltage parameters of the switch tube, the target drain-source voltage value is the sum of the positive cycle drain-source voltage value and the negative cycle drain-source voltage value of each switch tube, and performs fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value; because the present invention constructs an accurate fault diagnosis strategy through open-circuit fault analysis, and analyzes the drain-source voltage parameters of the switch tubes during the open-circuit fault in combination with the fault diagnosis strategy, high-efficiency fault diagnosis is achieved, and a large amount of data does not need to be processed and calculated, which effectively reduces the calculation complexity and avoids the problem of data processing delay, so that the fault is discovered and located in time, and the system is prevented from being shut down or damaged due to the expansion of the fault, thereby effectively improving the reliability and stability of the LLC resonant converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the description, are used to explain the principles of the present application.

[0057] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0058] Figure 1 It is a structural schematic diagram of an LLC resonant converter fault diagnosis device in a hardware operating environment involved in an embodiment of the present invention;

[0059] Figure 2 It is a flowchart of a first embodiment of a method for diagnosing a fault of an LLC resonant converter according to the present invention;

[0060] Figure 3 Schematic diagram of the structure of an LLC resonant converter in an embodiment of a method for diagnosing a fault of an LLC resonant converter according to the present invention;

[0061] Figure 4 This is a schematic diagram of analyzing the failure of the first upper switch tube T1 in an embodiment of the LLC resonant converter fault diagnosis method of the present invention, wherein:

[0062] Figure 4 (a) is a schematic diagram of a conduction circuit when T1 fails when T1 and T4 are turned on at the same time in an embodiment of the LLC resonant converter fault diagnosis method of the present invention;

[0063] Figure 4 (b) is a schematic diagram of a current loop when T1 fails, T1 and T4 are turned off, and T2 and T3 are turned on in an embodiment of the LLC resonant converter fault diagnosis method of the present invention;

[0064] Figure 4 (c) is a schematic diagram of a transient waveform of a drain-source voltage when a primary-side lower bridge arm device T1 fails in an embodiment of a fault diagnosis method for an LLC resonant converter according to the present invention;

[0065] Figure 5 This is a schematic diagram of analyzing the failure of the first lower switch tube T2 in an embodiment of the LLC resonant converter fault diagnosis method of the present invention, wherein:

[0066] Figure 5 (a) is a schematic diagram of a conduction circuit when T2 fails when T1 and T4 are turned on at the same time in an embodiment of the LLC resonant converter fault diagnosis method of the present invention;

[0067] Figure 5 (b) is a schematic diagram of a current loop when T2 fails, T1 and T4 are turned off, and T2 and T3 are turned on in an embodiment of the LLC resonant converter fault diagnosis method of the present invention;

[0068] Figure 5 (c) is a schematic diagram of a transient waveform of a drain-source voltage when a primary-side lower bridge arm device T2 fails in an embodiment of a fault diagnosis method for an LLC resonant converter according to the present invention;

[0069] Figure 6 Schematic diagram of the topological structure of the fault diagnosis circuit in an embodiment of the LLC resonant converter fault diagnosis method of the present invention;

[0070] Figure 7 It is a structural block diagram of the first embodiment of the LLC resonant converter fault diagnosis device of the present invention.

[0071] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0072] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0073] Reference Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of an LLC resonant converter fault diagnosis device in a hardware operating environment according to an embodiment of the present invention.

[0074] like Figure 1As shown, the LLC resonant converter fault diagnosis device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (Wireless-Fidelity, WI-FI) interface). The memory 1005 may be a high-speed random access memory (Random Access Memory, RAM), or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk storage. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0075] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the LLC resonant converter fault diagnosis device, and may include more or less components than those shown in the figure, or combine certain components, or arrange the components differently.

[0076] like Figure 1 As shown, the memory 1005 as a computer-readable storage medium may include an operating system, a network communication module, a user interface module, and an LLC resonant converter fault diagnosis program.

[0077] exist Figure 1 In the LLC resonant converter fault diagnosis device shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the LLC resonant converter fault diagnosis device of the present invention can be set in the LLC resonant converter fault diagnosis device, and the LLC resonant converter fault diagnosis device calls the LLC resonant converter fault diagnosis program stored in the memory 1005 through the processor 1001, and executes the LLC resonant converter fault diagnosis method provided by the embodiment of the present invention.

[0078] The embodiment of the present invention provides a method for diagnosing faults of an LLC resonant converter. Figure 2 , Figure 2 FIG. 1 is a flow chart of a first embodiment of a method for diagnosing faults of an LLC resonant converter according to the present invention.

[0079] In this embodiment, refer to Figure 3 , Figure 3 : is a schematic diagram of the structure of an LLC resonant converter, wherein the primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, wherein the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, and the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4, and the LLC resonant converter fault diagnosis method includes the following steps:

[0080] Step S10: performing an open circuit fault analysis on the LLC resonant converter, and generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result.

[0081] It should be noted that the execution subject of this embodiment may be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or a terminal electronic device capable of realizing the above functions, etc. The following takes the LLC resonant converter fault diagnosis device (hereinafter referred to as the diagnosis device) as an example to illustrate this embodiment and the following embodiments.

[0082] It should be noted that the open circuit fault analysis results include the drain-source voltage change law of the upper bridge arm on the primary side and / or the drain-source voltage change law of the lower bridge arm on the primary side when each switching tube fails, and the fault diagnosis strategy includes locating the faulty bridge arm in the LLC resonant converter based on the drain-source voltage change law.

[0083] It can be understood that the present embodiment obtains the drain-source voltage variation law when a fault occurs in each bridge arm of the LLC resonant converter through open-circuit fault analysis, and generates a fault diagnosis strategy based on the drain-source voltage variation law. The fault diagnosis strategy includes a mapping relationship between the drain-source voltage variation law and each fault condition. Thus, by monitoring the drain-source voltage variation of the LLC resonant converter and combining the fault diagnosis strategy, the fault condition corresponding to the drain-source voltage variation is determined, thereby locating the faulty bridge arm. The present embodiment does not need to collect, calculate and analyze a large amount of data, but only needs to monitor the drain-source voltage variation of the LLC resonant converter and combine the fault diagnosis strategy to achieve efficient and high-precision fault diagnosis.

[0084] In some embodiments, the LLC resonant converter is composed of three parts: a primary side full bridge, an LLC resonant cavity, and a secondary side uncontrolled rectifier bridge. Figure 3, the primary side full bridge can be composed of 4 silicon carbide metal oxide semiconductor field effect transistors (SiC MOSFET), which can easily operate at a frequency of 100~200kHz. Each SiC MOSFET is usually composed of a power transistor (T1~T4), a parasitic capacitor (C1~C4) and a body anti-parallel diode (VD1~VD4). The resonant cavity includes inductors Lr, Lm and capacitors Cr, where Lr and Cr are resonant inductors and resonant capacitors respectively, and Lm can be replaced by transformer excitation inductance. The secondary side uncontrolled rectifier bridge is composed of 4 Schottky diodes (D1~D4).

[0085] It is understandable that it is possible for different switch tubes on the primary side of the LLC resonant converter to have open-circuit faults at different times, and this situation is relatively common. Therefore, this embodiment can perform open-circuit fault analysis on each switch tube on the primary side of the LLC resonant converter, determine the drain-source voltage variation law when each switch tube fails, and generate a fault diagnosis strategy for the LLC resonant converter based on the drain-source voltage variation law.

[0086] In the specific implementation, the open circuit fault characteristics of T1 and T2 are analyzed as examples. They belong to the same bridge arm. gs1 ~V gs4 and V ds2 、V ds4 Respectively represent the primary side full-bridge switch tube drive voltage, the lower bridge arm device T2 drain-source voltage V ds2 and the drain-source voltage V ds4 Finally, the variation rules of the drain-source voltage of the lower bridge arm devices in one cycle after an open circuit fault occurs when all switch tubes T1 and T4 are turned on at the same time are summarized to generate a fault diagnosis strategy.

[0087] Furthermore, in order to accurately generate a fault diagnosis strategy and improve the accuracy of fault diagnosis, the above step S10 may include:

[0088] Step S101: Determine the conduction state of the test switch tube;

[0089] Step S102: performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube, and performing open circuit fault analysis on each switch tube on the primary side;

[0090] Step S103: generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result.

[0091] It should be noted that the above open circuit fault analysis results include the drain-source voltage variation rule of the upper bridge arm on the primary side and / or the drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails.

[0092] It should be noted that the conduction state of the test switch tube can be the conduction state of the switch tube used for testing in the open circuit fault analysis. For example, when testing the conduction state of the T1 switch tube and the T4 switch tube at the same time, an open circuit fault analysis is performed on the T1 switch tube, wherein the T1 switch tube and the T4 switch tube are the test switch tubes, and the state in which T1 and T4 are simultaneously turned on is the conduction state of the test switch tube.

[0093] In some embodiments, the diagnostic device can generate a fault diagnosis strategy by performing transient analysis on T1, T2, T3 and T4 respectively when OCF (overcurrent fault) occurs when the test switches T1 and T4 are turned on at the same time, using variable frequency control and ignoring dead time, and analyzing the transient waveform of the drain-source voltage of the primary side lower bridge arm device.

[0094] Furthermore, in order to comprehensively analyze the variation law of the drain-source voltage of the LLC resonant converter when each switch tube fails, the above step S102 may include:

[0095] Step S1021: obtaining a first drain-source voltage value of the switch tube to be analyzed;

[0096] Step S1022: controlling the first upper switch tube T1 and the second lower switch tube T4 to be turned on at the same time, and sending a shutdown signal to each switch tube respectively, so as to simulate an open circuit fault of each switch tube respectively;

[0097] Step S1023: acquiring a second drain-source voltage value of the switch to be analyzed in response to a failure of each switch tube;

[0098] Step S1024: after each switch tube fails, control the first upper switch tube T1 and the second lower switch tube T4 to be turned off at the same time and the first lower switch tube T2 and the second upper switch tube T3 to be turned on at the same time, and obtain a third drain-source voltage value of the switch tube to be analyzed;

[0099] Step S1025: performing open circuit fault analysis on each switch tube on the primary side based on the first drain-source voltage value, the second drain-source voltage value, and the third drain-source voltage value.

[0100] It should be noted that the test switch conduction state may include: the target switch tubes are simultaneously turned on and the target switch tubes are simultaneously closed, and the target switch tubes include the first upper switch tube T1 and the second lower switch tube T4, or the first lower switch tube T2 and the second upper switch T3.

[0101] It should be noted that the switch tubes to be analyzed include the first lower switch tube T2 and the second lower switch tube T4 , or the first upper switch tube T1 and the second upper switch tube T3 .

[0102] Furthermore, in order to accurately locate the fault, the fault diagnosis strategy includes drain-source voltage conditions corresponding to each fault type;

[0103] The drain-source voltage condition includes:

[0104] If the first upper switch tube T1 fails, the target drain-source voltage value is:

[0105]

[0106] If the first lower switch tube T2 fails, the target drain-source voltage value is:

[0107]

[0108] If the second upper switch tube T3 fails, the target drain-source voltage value is:

[0109]

[0110] If the second lower switch tube T4 fails, the target drain-source voltage value is:

[0111]

[0112] in, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0113] In some embodiments, an open circuit fault analysis of the first upper switch tube T1 and the second lower switch tube T4 is used as an example for explanation:

[0114] Analyze T1 fault: refer to Figure 4 , Figure 4 The circuit diagram and circuit parameter waveform diagram for analyzing the failure of the first upper switch tube T1 are shown in FIG. Figure 4 (a) is a schematic diagram of a conduction circuit when T1 and T4 are turned on at the same time and T1 fails in an embodiment; Figure 4 (b) is a schematic diagram of a current loop when T1 fails, T1 and T4 are turned off, and T2 and T3 are turned on in one embodiment; Figure 4 (c) is a schematic diagram of a transient waveform of a drain-source voltage when the primary-side lower bridge arm device T1 fails in an embodiment.

[0115] When T1 and T4 are turned on at the same time, the transient analysis after OCF (over current fault) occurs, the variable frequency control method is adopted, and the dead time is ignored. The transient waveform of the drain-source voltage of the lower bridge arm device on the primary side is as follows: Figure 4 (c) as shown;

[0116] T1 and T4 are turned on at the same time. At time tI, OCF occurs in T1. Since the current flowing through the resonant cavity cannot change suddenly, the current will continue to flow through the parasitic diode VD2 of T2. The circuit is as follows Figure 4 As shown in (a), before the fault occurs at time tI, the drain-source voltage V ds2 and V ds4 They are:

[0117]

[0118] After the fault occurs at time tI, the drain-source voltage V ds2 and V ds4 They are

[0119]

[0120] At time tII, T1 and T4 are turned off, and T2 and T3 are turned on, forming a current loop between T2, T3 and the resonant cavity, as shown in Figure 4 (b) shows the drain-source voltage V ds2 and V ds4 They are:

[0121]

[0122] Analysis of T2 fault: Refer to Figure 5 , Figure 5 The circuit diagram and circuit parameter waveform diagram are used to analyze the failure of the first lower switch tube T2. Figure 5 (a) is a schematic diagram of a conduction circuit when T1 and T4 are turned on at the same time and T2 fails in an embodiment; Figure 5 (b) is a schematic diagram of a current loop in which, when T2 fails, T1 and T4 are turned off, and T2 and T3 are turned on, in an embodiment; Figure 5 (c) is a schematic diagram of a transient waveform of a drain-source voltage when the primary-side lower bridge arm device T2 fails in an embodiment.

[0123] When T1 and T4 are turned on at the same time, the transient analysis after OCF occurs, using variable frequency control mode and ignoring the dead time, the transient waveform of the drain-source voltage of the lower bridge arm device on the primary side is as follows: Figure 5 (c) shown.

[0124] T1 and T4 are turned on at the same time, and OCF occurs in T2 at time tI. Before and after the fault occurs at time tI, T2 does not participate in the process of T1 and T4 being turned on at the same time. The circuit is as follows Figure 5 (a) shows the drain-source voltage V ds2 and V ds4They are:

[0125]

[0126] At time tII, T1 and T4 are turned off, and T2 and T3 are turned on. However, due to an open circuit failure of T2, the current cannot flow through T2. Therefore, the diode VD1 connected in parallel with T3 and T1 forms a freewheeling loop with the resonant cavity. Figure 5 (b) shows that the drain-source voltage of the lower bridge arm switch device V ds2 and V ds4 They are:

[0127]

[0128] Similarly, the open circuit faults of T3 and T4 are analyzed, and the drain-source voltage changes of the lower bridge arm devices T2 and T4 after one cycle after the fault are shown in Table 1. It can be seen that after the open circuit fault, the drain-source voltage of the lower bridge arm devices T2 and T4 will always change in certain modes compared to normal operation. This provides a certain theoretical basis for the subsequent fault diagnosis of this embodiment.

[0129] Table 1 Changes in drain-source voltage of lower bridge arm devices T2 and T4 after open circuit failure

[0130]

[0131] Step S20: in response to an open circuit fault occurring in the LLC resonant converter, collecting drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter.

[0132] It should be noted that the conventional diagnosis methods based on midpoint voltage value and resonant capacitor voltage, etc., have similar open-circuit fault characteristics of diagonal switches that are turned on simultaneously in the variable frequency control mode, which are difficult to distinguish, and will seriously affect the positioning accuracy of the open-circuit fault of the switch tube of the LLC converter under variable frequency control. Therefore, this embodiment monitors and analyzes the drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter, and performs fault diagnosis in combination with the fault diagnosis strategy, thereby ensuring the accuracy of the diagnosis results, reducing the calculation error and the amount of calculation data, and improving the efficiency of fault diagnosis.

[0133] In a specific implementation, the diagnostic device monitors the state of each switch tube in the LLC resonant converter. When a switch tube fails, the diagnostic device samples the drain-source voltage of each switch tube, and then pre-processes the sampled voltage (for example, may include amplification processing, filtering processing, etc.) to obtain the drain-source voltage parameters of the switch tube of each bridge arm.

[0134] In some embodiments, the diagnostic device can monitor and analyze the drain-source voltage value V of the lower bridge arm switch tube of the primary side in real time. ds2 and Vds4 (or the drain-source voltage value of the upper bridge arm switch tube V ds1 and V ds3 ) can detect and locate the open-circuit faults of switching devices quickly and accurately.

[0135] Step S30: determining a target drain-source voltage value of each switch tube based on the switch tube drain-source voltage parameter.

[0136] It should be noted that the above target drain-source voltage value is the sum of the positive cycle drain-source voltage value and the negative cycle drain-source voltage value of each switch tube, wherein the positive cycle and the negative cycle are both half cycles, and the positive cycle plus the negative cycle is a whole cycle.

[0137] In some embodiments, the present invention also proposes a simulation fault diagnosis circuit topology structure, referring to Figure 6 , Figure 6 The topological structure diagram of the fault diagnosis circuit is shown in FIG. 1 , and the topological structure of the fault diagnosis circuit includes a voltage sampling and conditioning circuit, an average voltage circuit, and a comparison and logic combination circuit;

[0138] The voltage sampling and conditioning circuit is composed of sampling voltage-dividing resistors R1, R2, R3 and R4, operational amplifiers U1, U2, and filter resistor-capacitor networks Rf1, Cf1 and Rf2, Cf2. The voltage sampling and conditioning circuit is connected to the drain and source ends of T2 and T4 tubes respectively. The drain-source voltage of T2 and T4 is divided by resistors and then processed by the operational conditioning circuit. Finally, the switching noise and high-frequency interference are filtered out by the filter circuit to obtain a relatively stable sampling instantaneous value. Taking T2 tube as an example, the drain-source voltage of T2 tube is V ds2 , the voltage sampled after the voltage divider resistor is (R1 / R2)×V ds2 Assuming that the gain of the operational amplifier is G1, the sampled voltage value V output by the voltage sampling and conditioning circuit is ds2_c = (R1 / R2)×V ds2 ×G1. Similarly, the T4 tube is the same.

[0139] The mean voltage circuit is composed of a resettable integrator consisting of operational amplifiers U3, U4 and integral resistors and capacitors RI1, RI2, CI1, CI, and voltage divider resistors Rd1, Rd2, Rd3, Rd4. Its purpose is to obtain the sum of the drain-source voltage values ​​of T2 and T4 tubes in the positive and negative half cycles V2 and V4. Taking T2 tube as an example, after passing through the voltage sampling and conditioning circuit, the voltage sampling value V of T2 tube can be obtained. ds2_c , integrating it over the whole cycle gives:

[0140]

[0141] Among them, t1 is the starting time of each cycle, and T is the cycle time.

[0142] During stable operation, V ds If they are all constants, then the integral formula can be simplified to obtain:

[0143]

[0144] Then use the resistor voltage divider to construct: Rd2 / (Rd1+Rd2)=2 / T, then the output value of the mean voltage circuit is:

[0145]

[0146] That is, the sum of the drain-source voltage values ​​in the positive and negative half cycles. Similarly, the T4 tube is the same.

[0147] The comparison and logic combination circuit can be composed of comparators U5, U6, U7, U8 and logic gate devices U9, U10, U11, U12. This part compares and logically combines the output value of the mean voltage circuit according to the fault diagnosis strategy to obtain variables FT1, FT2, FT3 and FT4 that characterize the fault information of each switch tube. A value of 1 indicates an open circuit fault.

[0148] Step S40: performing fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value.

[0149] In some embodiments, the diagnostic device can use the drain-source voltage V of the bridge arm switch tubes T2 and T4 in the positive and negative half cycles. ds2 and V ds4 The sum of the sampling values ​​is used to perform a logical combination judgment on the two to identify open circuit faults and locate faulty devices.

[0150] Furthermore, in order to quickly and accurately locate the switch tube fault, the above step S40 may include:

[0151] Step S401: determining a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4 based on the target drain-source voltage value;

[0152] Step S402: determining a fault type matching a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4 based on the fault diagnosis strategy;

[0153] Step S403: locating the faulty switch tube according to the fault type to perform fault diagnosis on the LLC resonant converter.

[0154] It can be understood that this embodiment uses the drain-source voltage V of the bridge arm switch tubes T2 and T4 in the positive and negative half cycles. ds2 and Vds4 The sum of the sampled values ​​is used to perform a logical combination judgment on the two to identify open circuit faults and locate faulty components. Its working principle is as follows:

[0155] When the LLC converter operates normally under variable frequency control, the sum of the drain-source voltages of the switches T2 and T4 in each full cycle is V2 and V4 respectively, then:

[0156]

[0157] After an open-circuit fault occurs in the LLC resonant converter, according to the above analysis, the drain-source voltage of the lower bridge arm devices T2 and T4 changes, causing the sum of the drain-source voltage values ​​of the positive and negative half-cycles to change. The sum of the drain-source voltage of the switch tubes T2 and T4 in each full cycle is V f2 and V f4 , then for different switch tubes that fail, the change rules are as follows:

[0158] When an open circuit fault occurs in T1, the following occurs:

[0159]

[0160] When an open circuit fault occurs in T2 tube, there are:

[0161]

[0162] When an open circuit fault occurs in T3 tube, the following occurs:

[0163]

[0164] When the T4 tube has an open circuit fault, there are:

[0165]

[0166] Furthermore, in order to reduce the influence of sampling error and noise, the fault diagnosis strategy also includes a fault error coefficient ;

[0167] The drain-source voltage condition also includes:

[0168] If the first upper switch tube T1 fails, the following formula is satisfied:

[0169] ,and

[0170] If the first lower switch tube T2 fails, the following formula is satisfied:

[0171] ,and

[0172] If the second upper switch tube T3 fails, the following formula is satisfied:

[0173] ,and

[0174] If the second lower switch tube T4 fails, the following formula is satisfied:

[0175] ,and

[0176] in, is the fault error coefficient, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0177] It should be noted that in order to reduce the influence of sampling error and noise, an error coefficient is introduced in the invention. The value range can be set according to the actual sampling circuit accuracy and interference intensity, and the error coefficient Generally less than 20%.

[0178] In some embodiments, the fault diagnosis principle is as follows:

[0179] First, the drain-source voltage values ​​of the lower bridge arm switch tubes T2 and T4 in the positive and negative half cycles are collected respectively, and then the sampled values ​​are accumulated by an adder to obtain the sum Vf2 and Vf4 of the drain-source voltage of the lower bridge arm switch tubes T2 and T4 in the positive and negative half cycles.

[0180] Then compare and logically combine the required Vf2 and Vf4. If formula (11) is satisfied, it is determined that the T1 tube has an open circuit fault.

[0181]

[0182] If formula (12) is satisfied, it is determined that tube T2 has an open circuit fault.

[0183]

[0184] If formula (13) is satisfied, it is determined that the T3 tube has an open circuit fault.

[0185]

[0186] If formula (14) is satisfied, it is determined that the T4 tube has an open circuit fault.

[0187]

[0188] Referring to Table 2, Table 2 summarizes the comparison between the sum of the drain-source voltage Vds2 and Vds4 sampling values ​​of the lower bridge arm switch tubes T2 and T4 in the positive and negative half cycles after an open circuit fault (OverCurrent Fault, OCF) occurs when the T1 and T4 tubes are turned on and running, and the normal operation. Based on the above theoretical analysis, this embodiment proposes to use the drain-source voltage value of the lower bridge arm switch tube to identify and locate the open circuit fault.

[0189]

[0190] In this embodiment, an open-circuit fault analysis is performed on the LLC resonant converter, and a fault diagnosis strategy for the LLC resonant converter is generated based on the open-circuit fault analysis result. In response to an open-circuit fault in the LLC resonant converter, drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter are collected, and a target drain-source voltage value of each switch tube is determined based on the drain-source voltage parameters of the switch tubes, the target drain-source voltage value being the sum of the positive cycle drain-source voltage value and the negative cycle drain-source voltage value of each switch tube. The LLC resonant converter is fault diagnosed based on the fault diagnosis strategy and the target drain-source voltage value. Since the open-circuit fault analysis is performed in this embodiment to construct an accurate fault diagnosis strategy, the drain-source voltage parameters of the switch tubes during the open-circuit fault are analyzed in combination with the fault diagnosis strategy, and efficient fault diagnosis is achieved without processing and calculating a large amount of data, which effectively reduces the calculation complexity and avoids the problem of data processing delay, thereby timely discovering and locating the fault, avoiding the expansion of the fault and causing system shutdown or damage, thereby effectively improving the reliability and stability of the LLC resonant converter.

[0191] In addition, an embodiment of the present invention further proposes a computer-readable storage medium, on which an LLC resonant converter fault diagnosis program is stored. When the LLC resonant converter fault diagnosis program is executed by a processor, the steps of the LLC resonant converter fault diagnosis method described above are implemented.

[0192] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0193] The computer-readable storage medium may be included in the LLC resonant converter fault diagnosis device; or may exist independently without being assembled into the LLC resonant converter fault diagnosis device.

[0194] In addition, an embodiment of the present invention further provides a computer program product, including an LLC resonant converter fault diagnosis program, which implements the steps of the LLC resonant converter fault diagnosis method described above when executed by a processor.

[0195] The specific implementation of the computer program product of the present invention is basically the same as the embodiments of the above-mentioned LLC resonant converter fault diagnosis method, and will not be repeated here.

[0196] Reference Figure 7 , Figure 7 It is a structural block diagram of the first embodiment of the LLC resonant converter fault diagnosis device of the present invention.

[0197] like Figure 7 As shown, the LLC resonant converter fault diagnosis device proposed in this embodiment includes: an open circuit fault analysis module 10, a drain-source voltage acquisition module 20, a drain-source voltage calculation module 30 and a fault diagnosis module 40;

[0198] The primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, and the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4;

[0199] The open circuit fault analysis module 10 is used to perform an open circuit fault analysis on the LLC resonant converter, and generate a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result, wherein the open circuit fault analysis result includes a drain-source voltage variation rule of the upper bridge arm on the primary side and / or a drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails, and the fault diagnosis strategy includes locating the faulty bridge arm in the LLC resonant converter based on the drain-source voltage variation rule;

[0200] The drain-source voltage acquisition module 20 is used to acquire drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter in response to an open circuit fault occurring in the LLC resonant converter;

[0201] The drain-source voltage calculation module 30 is used to determine the target drain-source voltage value of each switch tube based on the drain-source voltage parameter of the switch tube, and the target drain-source voltage value is the sum of the positive cycle drain-source voltage value and the negative cycle drain-source voltage value of each switch tube;

[0202] The fault diagnosis module 40 is used to perform fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value.

[0203] Furthermore, the open circuit fault analysis module 10 is also used to determine the conduction state of the test switch tube; based on the conduction state of the test switch tube, the primary side of the LLC resonant converter is frequency-controlled, and each switch tube on the primary side is subjected to open circuit fault analysis; and a fault diagnosis strategy for the LLC resonant converter is generated based on the open circuit fault analysis result.

[0204] Further, the test switch conduction state includes: the target switch is turned on at the same time and the target switch is closed at the same time, and the target switch includes the first upper switch T1 and the second lower switch T4, or the first lower switch T2 and the second upper switch T3;

[0205] The open circuit fault analysis module 10 is further used to obtain a first drain-source voltage value of a switch tube to be analyzed, wherein the switch tube to be analyzed includes the first lower switch tube T2 and the second lower switch tube T4, or the first upper switch tube T1 and the second upper switch T3; control the first upper switch tube T1 and the second lower switch tube T4 to be turned on at the same time, and send a shutdown signal to each switch tube respectively, so as to simulate an open circuit fault of each switch tube respectively; obtain a second drain-source voltage value of the switch tube to be analyzed in response to a fault of each switch tube respectively; after a fault occurs in each switch tube, control the first upper switch tube T1 and the second lower switch tube T4 to be turned off at the same time and the first lower switch tube T2 and the second upper switch T3 to be turned on at the same time, so as to obtain a third drain-source voltage value of the switch tube to be analyzed; and perform an open circuit fault analysis on each switch tube on the primary side based on the first drain-source voltage value, the second drain-source voltage value, and the third drain-source voltage value.

[0206] Furthermore, the fault diagnosis module 40 is also used to determine a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4 based on the target drain-source voltage value; determine a fault type that matches the target drain-source voltage value of the first lower switch tube T2 and the target drain-source voltage value of the second lower switch tube T4 based on the fault diagnosis strategy; and locate the faulty switch tube according to the fault type to perform fault diagnosis on the LLC resonant converter.

[0207] Further, the fault diagnosis strategy includes drain-source voltage conditions corresponding to each fault type;

[0208] The drain-source voltage condition includes:

[0209] If the first upper switch tube T1 fails, the target drain-source voltage value is:

[0210]

[0211] If the first lower switch tube T2 fails, the target drain-source voltage value is:

[0212]

[0213] If the second upper switch tube T3 fails, the target drain-source voltage value is:

[0214]

[0215] If the second lower switch tube T4 fails, the target drain-source voltage value is:

[0216]

[0217] in, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0218] Furthermore, the fault diagnosis strategy also includes a fault error coefficient;

[0219] The drain-source voltage condition also includes:

[0220] If the first upper switch tube T1 fails, the following formula is satisfied:

[0221] ,and

[0222] If the first lower switch tube T2 fails, the following formula is satisfied:

[0223] ,and

[0224] If the second upper switch tube T3 fails, the following formula is satisfied:

[0225] ,and

[0226] If the second lower switch tube T4 fails, the following formula is satisfied:

[0227] ,and

[0228] in, is the fault error coefficient, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

[0229] In this embodiment, an open-circuit fault analysis is performed on the LLC resonant converter, and a fault diagnosis strategy for the LLC resonant converter is generated based on the open-circuit fault analysis result. In response to an open-circuit fault in the LLC resonant converter, drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter are collected, and a target drain-source voltage value of each switch tube is determined based on the drain-source voltage parameters of the switch tubes, the target drain-source voltage value being the sum of the positive cycle drain-source voltage value and the negative cycle drain-source voltage value of each switch tube. The LLC resonant converter is fault diagnosed based on the fault diagnosis strategy and the target drain-source voltage value. Since the open-circuit fault analysis is performed in this embodiment to construct an accurate fault diagnosis strategy, the drain-source voltage parameters of the switch tubes during the open-circuit fault are analyzed in combination with the fault diagnosis strategy, and efficient fault diagnosis is achieved without processing and calculating a large amount of data, which effectively reduces the calculation complexity and avoids the problem of data processing delay, thereby timely discovering and locating the fault, avoiding the expansion of the fault and causing system shutdown or damage, thereby effectively improving the reliability and stability of the LLC resonant converter.

[0230] The LLC resonant converter fault diagnosis device provided by the present application adopts the LLC resonant converter fault diagnosis method in the above embodiment, which can solve the technical problem of LLC resonant converter fault diagnosis. Compared with the prior art, the beneficial effects of the LLC resonant converter fault diagnosis device provided by the present application are the same as the beneficial effects of the LLC resonant converter fault diagnosis method provided by the above embodiment, and other technical features in the LLC resonant converter fault diagnosis device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0231] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

[0232] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of them according to actual needs to achieve the purpose of the present embodiment, and no limitation is made here.

[0233] In addition, for technical details not fully described in this embodiment, reference may be made to the LLC resonant converter fault diagnosis method provided in any embodiment of the present invention, which will not be described in detail here.

[0234] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0235] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0236] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0237] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A LLC resonant converter fault diagnosis method, characterized in that: The primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4, and the LLC resonant converter fault diagnosis method includes: Performing an open-circuit fault analysis on the LLC resonant converter, and generating a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result, wherein the open-circuit fault analysis result includes a drain-source voltage variation rule of the upper bridge arm on the primary side and / or a drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails, and the fault diagnosis strategy includes locating a bridge arm having a fault in the LLC resonant converter based on the drain-source voltage variation rule; In response to an open circuit fault occurring in the LLC resonant converter, collecting drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter; Determine a target drain-source voltage value of each switch tube based on the switch tube drain-source voltage parameter, wherein the target drain-source voltage value is the sum of a positive cycle drain-source voltage value and a negative cycle drain-source voltage value of each switch tube; Performing fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value; The performing open circuit fault analysis on the LLC resonant converter and generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result includes: Determine the conduction state of the test switch tube; Performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube, and performing open circuit fault analysis on each switch tube on the primary side; Generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result; The test switch conduction state includes: the target switch is turned on at the same time and the target switch is closed at the same time, and the target switch includes the first upper switch T1 and the second lower switch T4, or the first lower switch T2 and the second upper switch T3; The step of performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube and performing open circuit fault analysis on each switch tube on the primary side includes: Acquire a first drain-source voltage value of a switch tube to be analyzed, wherein the switch tube to be analyzed includes the first lower switch tube T2 and the second lower switch tube T4, or the first upper switch tube T1 and the second upper switch tube T3; Controlling the first upper switch tube T1 and the second lower switch tube T4 to be turned on at the same time, and sending a shutdown signal to each switch tube respectively, so as to simulate an open circuit fault of each switch tube respectively; In response to each switch tube having a fault, obtaining a second drain-source voltage value of the switch tube to be analyzed; After each switch tube fails, the first upper switch tube T1 and the second lower switch tube T4 are controlled to be turned off at the same time, and the first lower switch tube T2 and the second upper switch tube T3 are controlled to be turned on at the same time, so as to obtain a third drain-source voltage value of the switch tube to be analyzed; An open circuit fault analysis is performed on each switch tube on the primary side based on the first drain-source voltage value, the second drain-source voltage value, and the third drain-source voltage value.

2. The LLC resonant converter fault diagnosis method according to claim 1, characterized in that: The performing fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value includes: Determine a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4 based on the target drain-source voltage value; Determine, based on the fault diagnosis strategy, a fault type that matches a target drain-source voltage value of the first lower switch tube T2 and a target drain-source voltage value of the second lower switch tube T4; The faulty switch tube is located according to the fault type to perform fault diagnosis on the LLC resonant converter.

3. The LLC resonant converter fault diagnosis method according to claim 2, characterized in that: The fault diagnosis strategy includes drain-source voltage conditions corresponding to each fault type; The drain-source voltage condition includes: If the first upper switch tube T1 fails, the target drain-source voltage value is: If the first lower switch tube T2 fails, the target drain-source voltage value is: If the second upper switch tube T3 fails, the target drain-source voltage value is: If the second lower switch tube T4 fails, the target drain-source voltage value is: in, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

4. The LLC resonant converter fault diagnosis method according to claim 3, characterized in that: The fault diagnosis strategy also includes a fault error coefficient; The drain-source voltage condition also includes: If the first upper switch tube T1 fails, the following formula is satisfied: ,and If the first lower switch tube T2 fails, the following formula is satisfied: ,and If the second upper switch tube T3 fails, the following formula is satisfied: ,and If the second lower switch tube T4 fails, the following formula is satisfied: ,and in, is the fault error coefficient, is the target drain-source voltage value of the first lower switch tube T2, is the target drain-source voltage value of the second lower switch tube T4, is the rated input voltage of the LLC resonant converter.

5. A fault diagnosis device for LLC resonant converter, characterized in that: The primary side of the LLC resonant converter includes a first bridge arm and a second bridge arm, the first bridge arm includes a first upper switch tube T1 and a first lower switch tube T2, the second bridge arm includes a second upper switch tube T3 and a second lower switch tube T4, and the LLC resonant converter fault diagnosis device includes: an open-circuit fault analysis module, configured to perform an open-circuit fault analysis on the LLC resonant converter, and generate a fault diagnosis strategy for the LLC resonant converter based on the open-circuit fault analysis result, wherein the open-circuit fault analysis result includes a drain-source voltage variation rule of the upper bridge arm on the primary side and / or a drain-source voltage variation rule of the lower bridge arm on the primary side when each switch tube fails, and the fault diagnosis strategy includes locating a bridge arm having a fault in the LLC resonant converter based on the drain-source voltage variation rule; A drain-source voltage acquisition module, configured to acquire drain-source voltage parameters of the switch tubes of each bridge arm in the LLC resonant converter in response to an open circuit fault occurring in the LLC resonant converter; A drain-source voltage calculation module, used to determine a target drain-source voltage value of each switch tube based on the drain-source voltage parameter of the switch tube, wherein the target drain-source voltage value is the sum of a positive cycle drain-source voltage value and a negative cycle drain-source voltage value of each switch tube; a fault diagnosis module, configured to perform fault diagnosis on the LLC resonant converter based on the fault diagnosis strategy and the target drain-source voltage value; The open circuit fault analysis module is also used to determine the conduction state of the test switch tube; Performing frequency conversion control on the primary side of the LLC resonant converter based on the conduction state of the test switch tube, and performing open circuit fault analysis on each switch tube on the primary side; generating a fault diagnosis strategy for the LLC resonant converter based on the open circuit fault analysis result; The test switch conduction state includes: the target switch is turned on at the same time and the target switch is closed at the same time, and the target switch includes the first upper switch T1 and the second lower switch T4, or the first lower switch T2 and the second upper switch T3; The open circuit fault analysis module is further used to obtain a first drain-source voltage value of a switch tube to be analyzed, wherein the switch tube to be analyzed includes the first lower switch tube T2 and the second lower switch tube T4, or the first upper switch tube T1 and the second upper switch tube T3; control the first upper switch tube T1 and the second lower switch tube T4 to be turned on at the same time, and send a shutdown signal to each switch tube respectively, so as to simulate an open circuit fault of each switch tube respectively; obtain a second drain-source voltage value of the switch tube to be analyzed in response to a fault of each switch tube respectively; after a fault occurs in each switch tube, control the first upper switch tube T1 and the second lower switch tube T4 to be turned off at the same time and the first lower switch tube T2 and the second upper switch tube T3 to be turned on at the same time, so as to obtain a third drain-source voltage value of the switch tube to be analyzed; and perform an open circuit fault analysis on each switch tube on the primary side based on the first drain-source voltage value, the second drain-source voltage value, and the third drain-source voltage value.

6. An LLC resonant converter fault diagnosis device, characterized in that: The LLC resonant converter fault diagnosis device comprises: a memory, a processor, and an LLC resonant converter fault diagnosis program stored in the memory and executable on the processor, wherein the LLC resonant converter fault diagnosis program is configured to implement the LLC resonant converter fault diagnosis method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores an LLC resonant converter fault diagnosis program, and when the LLC resonant converter fault diagnosis program is executed by a processor, the LLC resonant converter fault diagnosis method according to any one of claims 1 to 4 is implemented.

8. A computer program product, characterized in that The computer program product comprises an LLC resonant converter fault diagnosis program, and when the LLC resonant converter fault diagnosis program is executed by a processor, the steps of the LLC resonant converter fault diagnosis method according to any one of claims 1 to 4 are implemented.

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