Method, device and equipment for detecting health degree of switching device of buck-boost circuit

Abstract

The embodiment of the invention discloses a method, a device and equipment for detecting the health degree of a buck-boost circuit switching device. The detection method comprises the following steps: pre-charging a bus of a to-be-detected circuit to an initial bus voltage; according to a preset rule, the working state of each switching device in the circuit to be measured is changed, so that the expected output voltage alternately jumps between the first preset voltage and the initial bus voltage when the working state of each switching device is changed, and the real-time bus voltage and the real-time output voltage are measured; wherein the working states of the switching devices comprise the on state and the off state, the preset rule is formulated according to the positions of the switching devices in the circuit to be tested, and after the initial state starts, the two switching devices are kept in the on state at the same time; the preset rule represents the sequence of changing the working states of the switching devices; and judging whether the switching device is abnormal or not based on the real-time bus voltage and the output voltage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, in particular to a detection method, device and equipment for health degree of switching device of a boost-buck circuit. BACKGROUND

[0002] The boost-buck circuit is a commonly used DC / DC conversion circuit, and its output voltage can be lower or higher than the input voltage. It has a wide range of application scenarios in the fields of uninterruptible power supply, new energy and electric vehicles.

[0003] In the boost-buck circuit, if a device is abnormal, especially if a switching device is abnormal, the circuit cannot operate normally. How to detect the abnormality of the switching device in a timely and effective manner becomes a technical problem to be solved. SUMMARY

[0004] Therefore, the embodiments of the present application provide a detection method, device and equipment for health degree of switching device of a boost-buck circuit, which can effectively detect the abnormal state of the switching device and ensure the normal operation of the circuit.

[0005] The technical scheme of the embodiments of the present application is implemented as follows:

[0006] The detection method for health degree of switching device of a boost-buck circuit provided by the embodiments of the present application comprises the following steps: pre-charging a bus of a to-be-tested circuit to an initial bus voltage; changing working states of each switching device in the to-be-tested circuit according to a preset rule, so that an expected output voltage alternately jumps between a first preset voltage and the initial bus voltage when the working states of the switching devices change, and measuring a real-time bus voltage and an output voltage; wherein the working states of the switching devices include a conduction state and an off state, the preset rule is formulated according to positions of the switching devices in the to-be-tested circuit, both of the switching devices are kept in the conduction state after the initial state starts; the preset rule represents an order of changing the working states of each switching device; and whether the switching device is abnormal is judged based on the real-time bus voltage and the output voltage.

[0007] In the above scheme, changing the working states of each switching device in the to-be-tested circuit according to the preset rule comprises: starting from an initial state, changing the working states of each switching device in the to-be-tested circuit according to the preset rule; wherein in the initial state, each switching device is in the off state.

[0008] In the scheme, based on the bus voltage and the output voltage in real time, it is determined whether the switching device in the to-be-tested circuit is abnormal, including: if the bus voltage in real time is inconsistent with the initial bus voltage, it is determined that the switching device is abnormal; and / or, if the output voltage in real time is inconsistent with the expected output voltage, it is determined that the switching device is abnormal.

[0009] In the scheme, the initial bus voltage is determined based on the maximum withstand voltage of each switching device in the to-be-tested circuit; and the expected output voltage is determined according to the initial bus voltage.

[0010] In the scheme, the to-be-tested circuit includes a BUCK-BOOST circuit; the BUCK-BOOST circuit includes a first inductor, a second inductor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; wherein the switching device includes the first switch tube, the second switch tube, the third switch tube and the fourth switch tube; the first switch tube and the second switch tube and the third switch tube and the fourth switch tube are connected in series; one end of the first inductor is connected to the connection point of the first switch tube and the second switch tube; one end of the second inductor is connected to the connection point of the third switch tube and the fourth switch tube; the connection point of the second switch tube and the third switch tube is grounded; after the initial state starts, two switching devices are kept in the on state at the same time, including: after the initial state starts, two switching tubes are kept in the on state at the same time in each test step.

[0011] In the scheme, the test step includes:

[0012] Test step one: for the initial state, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all in the off state, and the bus voltage and the output voltage are measured;

[0013] Test step two: the first switch tube and the third switch tube are in the on state, and the second switch tube and the fourth switch tube are in the off state, and the bus voltage and the output voltage are measured;

[0014] Test step three: the second switch tube and the third switch tube are in the on state, and the first switch tube and the fourth switch tube are in the off state, and the bus voltage and the output voltage are measured;

[0015] Test step four: the second switch tube and the fourth switch tube are in the on state, and the first switch tube and the third switch tube are in the off state, and the bus voltage and the output voltage are measured;

[0016] Test Step 5: The second and third switching transistors are in the on state, the first and fourth switching transistors are in the off state, and the bus voltage and the output voltage are measured.

[0017] This application embodiment also provides a device for detecting the health of switching devices in a step-up / step-down circuit, comprising: a pre-charging module configured to pre-charge the bus of the circuit under test to an initial bus voltage; an adjustment module configured to change the operating state of each switching device in the circuit under test according to a preset rule, such that the expected output voltage alternates between a first preset voltage and the initial bus voltage when the operating state of the switching device changes; wherein the operating state of the switching device includes an on state and an off state, the preset rule is formulated based on the position of the switching device in the circuit under test, and after the initial state begins, two of the switching devices are kept in the on state simultaneously; the preset rule represents the order in which the operating states of each switching device are changed; a measurement module configured to measure the real-time bus voltage and output voltage; and a judgment module configured to determine whether the switching device is abnormal based on the real-time bus voltage and output voltage.

[0018] In the above scheme, the judgment module is further configured to determine that the switching device is abnormal if the real-time bus voltage is inconsistent with the initial bus voltage; and / or, determine that the switching device is abnormal if the real-time output voltage is inconsistent with the expected output voltage.

[0019] This application embodiment also provides a power conversion device, including a device for detecting the health of the switching devices in the buck-boost circuit described in the above solution.

[0020] Therefore, the embodiments of this application provide a method, apparatus, and device for detecting the health of switching devices in a step-up / step-down circuit. This method can change the operating state of each switching device in the circuit under test according to preset rules, and determine whether there are any abnormalities in the switching devices based on real-time measured bus voltage and output voltage. This allows for timely repair or replacement of the switching devices, ensuring the normal operation of the circuit. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an optional implementation process for a method to detect the health of a step-up / step-down circuit switching device provided in an embodiment of this application.

[0022] Figure 2 This is a topology diagram of the BUCK-BOOST circuit provided in an embodiment of this application;

[0023] Figure 3A schematic diagram of an optional structure for a device for detecting the health of a step-up / step-down circuit switching device provided in an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of an optional structure of the power conversion device provided in an embodiment of this application; Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application are further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the following description, references to "some embodiments" refer to a subset of all possible embodiments. It is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict. The terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this application.

[0028] Figure 1 This application provides a schematic diagram of the implementation process of a method for detecting the health of a step-up / step-down circuit switching device, as illustrated in the embodiments of this application. Figure 1 As shown, the method includes steps S101 to S103.

[0029] S101. Precharge the bus of the circuit under test to the initial bus voltage.

[0030] In this embodiment of the application, when starting to test the switching devices in the circuit under test, the bus of the circuit under test needs to be pre-charged to the initial bus voltage. The initial bus voltage is determined based on the maximum withstand voltage of each switching device in the circuit under test.

[0031] refer to Figure 2 Bus voltage includes positive bus voltage V bus+ and negative bus voltage V bus- Among them, the positive bus voltage V bus+ It needs to be pre-charged to a positive voltage, negative bus voltage Vbus- It needs to be pre-charged to a negative voltage. For example, the positive bus voltage V can be... bus+ Precharge to 100V, and, reduce the negative bus voltage V bus- Precharge to -100V.

[0032] In this embodiment of the application, before the device is powered on, a small voltage can be used to precharge the bus of the circuit under test in the device, thereby detecting the devices in the circuit under test. In this way, abnormal states of devices can be detected in advance, and the impact on the circuit caused by device abnormalities can be prevented.

[0033] S102. According to the preset rules, change the working state of each switching device in the circuit under test so that the expected output voltage alternates between the first preset voltage and the initial bus voltage when the working state of the switching device changes, and measure the real-time bus voltage and output voltage.

[0034] In this embodiment, the operating states of the switching devices include an ON state and an OFF state. The preset rules are determined based on the position of the switching devices in the circuit under test. After the initial state begins, both switching devices are simultaneously kept in the ON state. The preset rules characterize the order in which the operating states of each switching device are changed; that is, according to the preset rules, the operating states of each switching device will be changed in a specific order, and the expected output voltage will change each time the operating state of a switching device is changed. This allows the expected output voltage to alternate between a first preset voltage and an initial bus voltage. The first preset voltage can be 0, and the initial bus voltage can be a positive initial bus voltage of 100V or a negative initial bus voltage of -100V. For example, according to the preset rules, the expected output voltage can alternate between 0 and -100V, 0 and 100V, and 0.

[0035] In some embodiments of this application, the operating state of each switching device in the circuit under test can be changed according to a preset rule, starting from an initial state; wherein, in the initial state, each switching device is in the off state.

[0036] In some embodiments of this application, the circuit under test includes a BUCK-BOOST circuit. For example... Figure 2 As shown, the BUCK-BOOST circuit includes: a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4.

[0037] In this embodiment of the application, reference is made to Figure 2The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are connected in series. One end of the first inductor L1 is connected to the connection point of the first switch S1 and the second switch S2, and one end of the second inductor L2 is connected to the connection point of the third switch S3 and the fourth switch S4. The connection point of the second switch S2 and the third switch S3 is grounded. The expected output voltage is the battery charging voltage V. Bat .

[0038] It should be noted that, for Figure 2 The circuit topology shown can be tested according to the steps shown in Table 1.

[0039] Table 1

[0040] Step S11 S12 S13 S14 Expected V Bat ]] 1 Off Off Off Off 0V 2 On Off On Off 100V 3 Off On On Off 0V 4 Off On Off On -100V 5 On Off Figure 2 Figure 2 0V

[0041] In this embodiment of the application, steps 1 to 5 shown in Table 1 can be followed to complete the process. Figure 2 The health check of the BUCK-BOOST circuit switching transistors is described in step 1, which shows the initial state of the check. Specifically, in step 1, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all in the off state, allowing for the measurement of the real-time bus voltage V. bus+ and V bus- and output voltage V Bat Then, step 2 can be executed to turn on the first switch S1 and the third switch S3. At the same time, the real-time bus voltage V can be measured. bus+ and V bus- and output voltage V Bat Then, step 3 can be executed to turn off the first switch S1 and turn on the second switch S2. At this time, the third switch S3 remains on, and the real-time bus voltage V can be measured. bus+ and V bus- and output voltage V Bat Then, step 4 can be executed to turn off the third switch and turn on the fourth switch S4. At this time, the second switch S2 remains on, and the real-time bus voltage V can be measured. bus+ and V bus- and output voltage V Bat Then, step 5 can be executed to turn off the fourth switch S4 and turn on the third switch S3. At this time, the second switch S2 remains on, and the real-time bus voltage V can be measured. bus+ and V bus- and output voltage V Bat And that completes the task. Figure 2 Testing the health of the switching transistors in the BUCK-BOOST circuit.

[0042] It should be noted that if an abnormality occurs during the testing process, the testing can be stopped to confirm and resolve the abnormality. In other words, if an abnormality occurs while performing any step in Table 1, the execution of other steps in Table 1 can be stopped.

[0043] S103. Based on the real-time bus voltage and output voltage, determine whether there is any abnormality in the switching device.

[0044] In some embodiments of this application, the measured real-time bus voltage can be compared with the initial bus voltage during pre-charging; if the real-time bus voltage is inconsistent with the initial bus voltage, it is determined that there is an abnormality in the switching device.

[0045] In some embodiments of this application, the measured real-time output voltage can be compared with the expected output voltage; if the real-time output voltage is inconsistent with the expected output voltage, it is determined that there is an abnormality in the switching device.

[0046] Follow steps 1-5 as shown in Table 1. Figure 3 After testing the circuit topology, the rules shown in Table 2 can be used to determine whether there are any abnormalities in each switching device.

[0047] Table 2

[0048]

[0049]

[0050] In this embodiment of the application, if the real-time output voltage V obtained in step 1 of Table 1... Bat Compared with the expected output voltage (expected V) Bat The output voltage V obtained in step 1 is inconsistent, that is, the real-time output voltage V is inconsistent. Bat If the voltage is not 0V, then, referring to Table 2, it can be determined that the first switch S1 or the fourth switch S4 is either broken down or driven constantly high, that is, the first switch S1 or the fourth switch S4 is short-circuited. Specifically, if the real-time output voltage V... Bat For V bus+ Then it can be determined that the first switch S1 is short-circuited. If the real-time output voltage V Bat For V bus- Therefore, it can be determined that the fourth switch S4 is short-circuited.

[0051] If the real-time output voltage V obtained in step 2 of Table 1 is... Bat Compared with the expected output voltage (expected V) Bat The output voltage V obtained in step 2 is inconsistent, meaning it is inconsistent with the real-time output voltage V. BatIf the voltage is not 100V, then, referring to Table 2, it can be determined that the drive of the first switching transistor S1 has failed, that is, the first switching transistor S1 is open-circuited. Simultaneously, if the real-time positive bus voltage V obtained in step 2 of Table 1... bus+ The real-time positive bus voltage V obtained in step 2 is inconsistent with the initial positive bus voltage. bus+ If the voltage is not 100V, then, referring to Table 2, it can be determined that the second switch S2 is either broken down or driven by a constant high voltage, that is, the second switch S2 is short-circuited. If the real-time negative bus voltage V obtained in step 2 of Table 1... bus- The real-time negative bus voltage V obtained in step 2 is inconsistent with the initial negative bus voltage. bus- If it is not -100V, then, referring to Table 2, it can be determined that the fourth switch S4 is either broken down or driven by a constant high voltage, that is, the fourth switch S4 is short-circuited.

[0052] If the real-time output voltage V obtained in step 3 of Table 1 is... Bat Compared with the expected output voltage (expected V) Bat The output voltage V obtained in step 3 is inconsistent, that is, the real-time output voltage V is inconsistent. Bat If the voltage is not 0V, then, referring to Table 2, it can be determined that the drive of the second switch S2 has failed, that is, the second switch S2 is open-circuited. If the real-time positive bus voltage V obtained in step 3 of Table 1 is... bus+ The real-time positive bus voltage V obtained in step 3 is inconsistent with the initial positive bus voltage. bus+ If the voltage is not 100V, then, referring to Table 2, it can be determined that the first switch S1 is either broken down or driven by a constant high voltage, that is, the first switch S3 is short-circuited.

[0053] If the real-time output voltage V obtained in step 4 of Table 1 is... Bat Compared with the expected output voltage (expected V) Bat The output voltage V obtained in step 4 is inconsistent, that is, the real-time output voltage V is inconsistent. Bat If it is not -100V, then, referring to Table 2, it can be determined that the drive of the fourth switch S4 has failed, that is, the fourth switch S4 is open-circuited. If the real-time negative bus voltage V obtained in step 4 of Table 1 is... bus- The real-time negative bus voltage V obtained in step 4 is inconsistent with the initial negative bus voltage. bus- If it is not -100V, then, referring to Table 2, it can be determined that the third switch S3 is either broken down or driven by a constant high voltage, that is, the third switch S3 is short-circuited.

[0054] If the real-time output voltage V obtained in step 5 of Table 1 is... Bat Compared with the expected output voltage (expected V) Bat The output voltage V obtained in step 5 is inconsistent, meaning it is inconsistent with the real-time output voltage V. BatIf it is not 0V, then, referring to Table 2, it can be determined that the drive of the third switch S3 is faulty, that is, the third switch S3 is open-circuited.

[0055] It should also be noted that the switching device in the embodiments of this application can be either an IGBT (Insulated-Gate Bipolar Transistor) or a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor). For example... Figure 3 The switches S1, S2, S3 and S4 shown can be IGBTs or MOSFETs.

[0056] In this embodiment, the bus voltage can be used to detect the state of the device, thus enabling faster and more comprehensive detection of the status of the switching devices in the circuit under test.

[0057] It is understood that the detection method provided in this application can effectively detect abnormal states of switching devices, thereby enabling timely repair or replacement of the switching devices and ensuring the normal operation of the circuit. For example, the buck-boost circuit can be tested when the equipment is powered on. If there are no abnormalities in the components of the buck-boost circuit, the equipment can be powered on normally; if there are abnormalities in the components of the buck-boost circuit, the equipment needs to be stopped in time for repair or replacement.

[0058] In this embodiment of the application, before the device is powered on, a small voltage can be used to precharge the bus of the circuit under test in the device, thereby detecting the devices in the circuit under test. In this way, abnormal states of devices can be detected in advance, and the impact on the circuit caused by device abnormalities can be prevented.

[0059] Figure 4 This application provides a schematic diagram of the structural composition of a device for detecting the health status of a step-up / step-down circuit switching device, as shown in the embodiment of this application. Figure 4 As shown, the health detection device 200 for step-up / step-down circuit switching devices includes: a pre-charging module 210, an adjustment module 220, a measurement module 230, and a judgment module 240.

[0060] The pre-charge module 210 is configured to pre-charge the bus of the circuit under test to the initial bus voltage. The adjustment module 220 is configured to change the operating state of each switching device in the circuit under test according to preset rules, so that the expected output voltage alternates between a first preset voltage and the initial bus voltage when the operating state of the switching devices changes. The measurement module 230 is configured to measure the real-time bus voltage and output voltage. The judgment module 240 is configured to determine whether there is an abnormality in the switching devices based on the real-time bus voltage and output voltage.

[0061] In this embodiment, the operating states of the switching devices include an ON state and an OFF state. The preset rule is determined based on the position of the switching devices in the circuit under test. After the initial state begins, both switching devices are kept in the ON state simultaneously. The preset rule characterizes the order in which the operating states of each switching device are changed; that is, according to the preset rule, the operating states of each switching device will be changed in a specific order, and the expected output voltage will change each time the operating state of a switching device is changed.

[0062] In some embodiments of this application, the adjustment module 220 is further configured to change the operating state of each switching device in the circuit under test according to a preset rule, starting from an initial state. In the initial state, all switching devices are in a closed state.

[0063] In some embodiments of this application, the judgment module 240 is further configured to determine that the switching device is abnormal if the real-time bus voltage is inconsistent with the initial bus voltage; and / or, determine that the switching device is abnormal if the real-time output voltage is inconsistent with the expected output voltage.

[0064] In some embodiments of this application, the initial bus voltage is determined based on the maximum withstand voltage of each switching device in the circuit under test.

[0065] In some embodiments of this application, the switching device includes an IGBT or a MOSFET.

[0066] Figure 4 This is a schematic diagram of the composition structure of a power conversion device provided in an embodiment of this application, as shown below. ​ As shown, the power conversion device 300 includes: a detection device 200 for the health status of the switching devices in the step-up / step-down circuit.

[0067] In this embodiment of the application, reference is made to ​ The power conversion device 300 also includes a circuit under test 100. The circuit under test 100 may include a BUCK-BOOST circuit.

[0068] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above steps / processes do not imply a sequential order of execution; the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above embodiments of this application are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0069] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0070] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0071] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0072] Furthermore, in the various embodiments of this application, all functional units can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in a combination of hardware and software functional units. Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0073] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence or the part that contributes to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium, including instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, magnetic disks, or optical disks.

[0074] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method of detecting the health of a switching device of a boost-buck circuit, characterized by, The method comprises: pre-charging a bus of a to-be-tested circuit to an initial bus voltage; changing working states of each switch device in the to-be-tested circuit according to a preset rule, so that an expected output voltage alternately jumps between a first preset voltage and the initial bus voltage when the working states of the switch devices change, and measuring a real-time bus voltage and an output voltage; wherein the working states of the switch devices include a conducting state and an off state, the preset rule is formulated according to positions of the switch devices in the to-be-tested circuit, and both of the switch devices are kept in the conducting state after the initial state starts; the preset rule represents an order of changing the working states of each switch device; judging whether the switch device is abnormal based on the real-time bus voltage and the output voltage.

2. The method of claim 1, wherein the method further comprises: The method of changing the working states of each switch device in the to-be-tested circuit according to the preset rule comprises: starting from the initial state, changing the working states of each switch device in the to-be-tested circuit according to the preset rule; wherein each switch device is in the off state in the initial state.

3. The method of claim 1, wherein the method further comprises: The method of judging whether the switch device in the to-be-tested circuit is abnormal based on the real-time bus voltage and the output voltage comprises: if the real-time bus voltage is inconsistent with the initial bus voltage, it is judged that the switch device is abnormal; and / or if the real-time output voltage is inconsistent with the expected output voltage, it is judged that the switch device is abnormal.

4. The method of claim 1, wherein: the initial bus voltage is determined based on a maximum withstand voltage of each switch device in the to-be-tested circuit; and the expected output voltage is determined according to the initial bus voltage.

5. The method of claim 2, wherein the step of determining the health of the switching device comprises: The to-be-tested circuit comprises a BUCK-BOOST circuit, and the BUCK-BOOST circuit comprises a first inductor, a second inductor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; wherein the switch devices include the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube; the first switch tube and the second switch tube are connected in series with the third switch tube and the fourth switch tube; one end of the first inductor is connected to a connection point of the first switch tube and the second switch tube; one end of the second inductor is connected to a connection point of the third switch tube and the fourth switch tube; and the connection point of the second switch tube and the third switch tube is grounded. After the initial state starts, both of the switch devices are kept in the conducting state, which comprises that, after the initial state starts, two switch tubes are in the conducting state at each test step.

6. The method of claim 5, wherein the method further comprises: The test steps comprise: Test Step One: the initial state, in which the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all in the off state, and the bus voltage and the output voltage are measured. Test step two: the first switch tube and the third switch tube are in the on state, the second switch tube and the fourth switch tube are in the off state, and the bus voltage and the output voltage are measured; Test step three: the second switch tube and the third switch tube are in the on state, the first switch tube and the fourth switch tube are in the off state, and the bus voltage and the output voltage are measured; Test step four: the second switch tube and the fourth switch tube are in the on state, the first switch tube and the third switch tube are in the off state, and the bus voltage and the output voltage are measured; Test step five: the second switch tube and the third switch tube are in the on state, the first switch tube and the fourth switch tube are in the off state, and the bus voltage and the output voltage are measured.

7. A device for detecting the health of a switching device of a boost-buck circuit, characterized in that Comprising: a pre-charge module configured to pre-charge a bus of a to-be-tested circuit to an initial bus voltage; an adjustment module configured to change the working state of each switch device in the to-be-tested circuit according to a preset rule, so that the expected output voltage alternately jumps between a first preset voltage and the initial bus voltage when the working state of the switch device changes; wherein the working state of the switch device includes an on state and an off state, the preset rule is formulated according to the position of the switch device in the to-be-tested circuit, and both of the switch devices are kept in the on state after the initial state; the preset rule represents the order of changing the working state of each switch device; a measurement module configured to measure the real-time bus voltage and output voltage; a judgment module configured to judge whether the switch device is abnormal based on the real-time bus voltage and output voltage.

8. The detection device for the health of the switch device of the boost-buck circuit according to claim 7, wherein the judgment module is further configured to judge that the switch device is abnormal if the real-time bus voltage is inconsistent with the initial bus voltage, and / or judge that the switch device is abnormal if the real-time output voltage is inconsistent with the expected output voltage.

9. A power conversion device, characterized by comprising: Comprising: the detection device for the health of the switch device of the boost-buck circuit according to claim 7 or 8.

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