Fault detection method of switching tube, calculation module, device and power converter

Abstract

The invention provides a fault detection method of a switching tube, a calculation module, a device and a power converter, and the method comprises the steps: collecting a first current collected by each first sampling module based on a preset sampling frequency; aiming at any sampling moment, determining the first-order change of the first current at the sampling moment based on the first current collected at the sampling moment and the first current collected at the previous sampling moment; based on the first-order change of the first current at the sampling moment and the first-order change of the first current at the previous sampling moment, determining the second-order change of the first current at the sampling moment; and if the first-order change of the first current of any first sampling module is greater than a preset first-order change threshold value, or the second-order change of the first current of any first sampling module is greater than a preset second-order change threshold value, determining that a switching tube of the multi-path three-level DCDC power supply converter has an open circuit fault at the sampling moment. In this way, whether the switch tube breaks down or not is determined by detecting the balance degree of the current in the three-level middle line of the switch tube, and the detection efficiency of switch tube fault detection is improved.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a fault detection method, a calculation module, a device and a power converter for a switching tube. Background Art

[0002] As the demand for high-efficiency power products increases, the reliability of power converters becomes particularly important. Especially in high-current parallel three-level DCDC power converters, the switch tube is a key and vulnerable component, and its fault detection is crucial to ensure the stable operation of the entire system.

[0003] The existing switch tube fault detection method detects whether each switch tube has a fault by connecting each switch tube of the high current parallel three-level DCDC power converter to the detection circuit. However, as the parallel branches of the power converter increase, the detection circuit cost and detection time required to detect each switch tube increase exponentially, and the detection efficiency of switch tube fault detection is low. Summary of the invention

[0004] In view of this, the embodiments of the present application at least provide a switching tube fault detection method, calculation module, device and power converter, which determine whether the switching tube has a fault by detecting the balance degree of the three-level neutral line current of the switching tube, thereby improving the detection efficiency of the switching tube fault detection.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, an embodiment of the present application provides a fault detection method for a switching tube, which is applied to a computing module of a fault detection device for a switching tube, wherein the fault detection device also includes a fault detection circuit, wherein the fault detection circuit includes at least one detection resistor and a first sampling module corresponding to the detection resistor; any of the detection resistors is located on a three-level neutral line of two adjacent switching tubes in a multi-channel three-level DCDC power converter; any of the detection resistors is electrically connected to an input end of the corresponding first sampling module; and the output ends of each of the first sampling modules are electrically connected to the computing module respectively; the fault detection method includes:

[0007] Based on a preset sampling frequency, the first current collected by each first sampling module is collected; the first current is the current flowing through the detection resistor corresponding to the first sampling module;

[0008] For any sampling moment, based on the first current collected at the sampling moment and the first current collected at the previous sampling moment, determine a first-order change of the first current collected at the sampling moment;

[0009] For any sampling moment, based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment, determine the second-order change of the first current collected at the sampling moment;

[0010] For any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, it is determined that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

[0011] In a second aspect, an embodiment of the present application further provides a calculation module, which is applied to a fault detection device of a switch tube, wherein the fault detection device also includes a fault detection circuit, wherein the fault detection circuit includes at least one detection resistor and a first sampling module corresponding to the detection resistor; any of the detection resistors is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any of the detection resistors is electrically connected to the input end of the corresponding first sampling module; the output ends of each of the first sampling modules are electrically connected to the calculation module respectively; the calculation module includes:

[0012] A sampling unit, configured to collect the first current collected by each first sampling module based on a preset sampling frequency; the first current is the current flowing through the detection resistor corresponding to the first sampling module;

[0013] A first determining unit is used to determine, for any sampling moment, a first-order change of the first current collected at the sampling moment based on the first current collected at the sampling moment and the first current collected at the previous sampling moment;

[0014] A second determining unit is used to determine, for any sampling moment, a second-order change of the first current collected at the sampling moment based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment;

[0015] A judgment unit is used to determine, for any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

[0016] In a third aspect, an embodiment of the present application further provides a fault detection device for a switch tube, the fault detection device comprising:

[0017] A fault detection circuit and a calculation module in the above second aspect.

[0018] In a fourth aspect, an embodiment of the present application further provides a power converter, comprising the switch tube fault detection device in the third aspect above.

[0019] The embodiments of the present application provide a switch tube fault detection method, a calculation module, a device and a power converter, wherein the switch tube fault detection method is applied to a calculation module of a switch tube fault detection device, the fault detection device also includes a fault detection circuit, the fault detection circuit includes at least one detection resistor and a first sampling module corresponding to the detection resistor; any detection resistor is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any detection resistor is electrically connected to the input end of the corresponding first sampling module; the output end of each first sampling module is electrically connected to the calculation module respectively; the fault detection method includes: based on a preset sampling frequency, collecting the first current collected by each first sampling module; the first current is flowing through the first sampling module The current of the detection resistor corresponding to the block; for any sampling moment, based on the first current collected at the sampling moment and the first current collected at the previous sampling moment, determine the first-order change of the first current collected at the sampling moment; for any sampling moment, based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment, determine the second-order change of the first current collected at the sampling moment; for any sampling moment, if the first-order change of the first current collected by any first sampling module is greater than the preset first-order change threshold, or the second-order change of the first current collected by any first sampling module is greater than the preset second-order change threshold, it is determined that the switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment. In this way, by detecting the balance degree of the three-level neutral line current of the switch tube, it is determined whether the switch tube has a fault, and the detection efficiency of the switch tube fault detection is improved.

[0020] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 One of the structural schematic diagrams of a switch tube fault detection device provided in an embodiment of the present application is shown;

[0023] Figure 2A second structural schematic diagram of a switch tube fault detection device provided in an embodiment of the present application is shown;

[0024] Figure 3 A flow chart of a switch tube fault detection method provided in an embodiment of the present application is shown;

[0025] Figure 4 A schematic diagram showing the structure of an equivalent circuit model of a fault detection circuit provided in an embodiment of the present application is shown;

[0026] Figure 5 One of the functional module diagrams of a computing module provided in an embodiment of the present application is shown;

[0027] Figure 6 A second functional module diagram of a computing module provided in an embodiment of the present application is shown;

[0028] Figure 7 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0030] The following will be combined Figure 1 as well as Figure 2 The implementation method of the embodiment of the present application is described in detail; the fault detection method of the switching tube provided by the embodiment of the present application is applied to the computing module of the fault detection device of the switching tube.

[0031] See also Figure 1 , Figure 1 This is one of the structural schematic diagrams of a switch tube fault detection device provided in an embodiment of the present application. The switch tube fault detection method provided in an embodiment of the present application can be applied to Figure 1 The computing module of the fault detection device of the switch tube shown in the figure, the fault detection device of the switch tube also includes a fault detection circuit, the fault detection circuit includes at least one detection resistor and a first sampling module corresponding to the detection resistor. Figure 1As shown, taking a three-way three-level DCDC power converter as an example, the power converter has three branches, including the common input inductor L1, the upper half-bridge output capacitor C1 and the lower half-bridge output capacitor C11 of the three branches, the upper half-bridge diode D1, the upper half-bridge switch tube Q1, the lower half-bridge switch tube Q11 and the lower half-bridge diode D11 of the first branch, the upper half-bridge diode D2, the upper half-bridge switch tube Q2, the lower half-bridge switch tube Q12 and the lower half-bridge diode D12 of the second branch, and the upper half-bridge diode D3, the upper half-bridge switch tube Q3, the lower half-bridge switch tube Q13 and the lower half-bridge diode D13 of the third branch. Among them, the switch tubes Q1-Q13 are insulated gate bipolar transistors (IGBT). During the operation of the power converter, the switch tubes Q1-Q13 are controlled to be turned on or off at the same time through pulse width modulation (PWM). As shown Figure 1 As shown, the fault detection device 100 of the switch tube includes: a first detection resistor 110 and a first sampling module 120 of the first detection resistor located on the three-level neutral line of the first branch and the second branch, a second detection resistor 111 and a first sampling module 121 of the second detection resistor located on the three-level neutral line of the second branch and the third branch, and a calculation module 130. The first detection resistor 110 is electrically connected to the input end of the first sampling module 120 of the first detection resistor, and the second detection resistor 111 is electrically connected to the input end of the first sampling module 121 of the second detection resistor; the output end of the first sampling module 120 of the first detection resistor and the output end of the first sampling module 121 of the second detection resistor are electrically connected to the calculation module 130 respectively.

[0032] The first detection resistor 110 and the second detection resistor 111 are used for voltage sampling and current calculation.

[0033] The first sampling module 120 of the first detection resistor and the first sampling module 121 of the second detection resistor are used to collect currents flowing through the first detection resistor 110 and the second detection resistor 111 .

[0034] In the preferred embodiment of the present application, please refer to Figure 2 , Figure 2 The second structural diagram of a switch tube fault detection device provided in the embodiment of the present application. The switch tube fault detection method provided in the embodiment of the present application can be applied to Figure 2 The calculation module in the fault detection device of the switch tube shown in FIG. Figure 2As shown, taking a three-way three-level DCDC power converter as an example, the fault detection device 100 may further include: a second acquisition module 140; the input end of the second acquisition module 140 is electrically connected to the three-level positive bus BUS+, the three-level neutral line BUS_N and the three-level negative bus BUS- of the three-way three-level DCDC power converter respectively; the output end of the second acquisition module 140 is electrically connected to the calculation module 130.

[0035] The second acquisition module 140 is used to acquire the voltage between the three-level positive bus BUS+ and the three-level neutral line BUS_N, and between the three-level neutral line BUS_N and the three-level negative bus BUS- of the multiple three-level DCDC power converters.

[0036] A fault detection method for a switching tube provided in an embodiment of the present application is described in detail below. The fault detection method can be applied to a calculation module of the fault detection device of the switching tube mentioned above.

[0037] See also Figure 3 , Figure 3 This is a flow chart of a switch tube fault detection method provided by an embodiment of the present application. Figure 3 As shown, the switch tube fault detection method provided in the embodiment of the present application includes the following steps:

[0038] S301 , based on a preset sampling frequency, sampling a first current collected by each first sampling module; the first current is a current flowing through a detection resistor corresponding to the first sampling module.

[0039] Here, please see Figure 4 , Figure 4 This is a schematic diagram of the structure of the equivalent circuit model of the fault detection circuit provided in the embodiment of the present application. First of all, it should be noted that: Figure 4 The resistors R0 and R3 in the figure are virtual sampling resistors set to assist in calculation and do not exist in the actual circuit. Figure 4 As shown, taking a three-way three-level DCDC power converter as an example, when the switch tubes Q1-Q13 are turned on, the current flowing through each branch is balanced, and the current in the horizontal direction of the three-level neutral line BUS_N from R0, R1, R2 to R3 is very small. When any of the switch tubes Q1-Q13 has a short circuit fault, the upper half bridge or the lower half bridge of the branch with the fault cannot be turned on, causing the current to flow from the upper half bridge of the branch with the fault to the lower half bridge of other branches through the three-level neutral line, or from the upper half bridge of other branches to the lower half bridge of the branch with the fault. At this time, the three-level neutral line has a drastically changing unbalanced current. Therefore, the current on the three-level neutral line can be sampled to monitor the drastically changing unbalanced current of the three-level neutral line, and then determine whether there is a short circuit fault in the switch tube.

[0040] Specifically, based on the preset sampling frequency, the first current collected by each first sampling module is collected; wherein the first current is the current flowing through the detection resistor corresponding to the first sampling module. The preset sampling frequency is set according to the conduction frequency of the switch tube. In the embodiment of the present application, the preset sampling frequency is set to a frequency that enables each first sampling module to perform sampling at the conduction midpoint of each switch tube driven by PWM.

[0041] S302 , for any sampling moment, based on the first current collected at the sampling moment and the first current collected at the previous sampling moment, determining a first-order change of the first current collected at the sampling moment.

[0042] Here, in order to determine whether a drastically changing unbalanced current occurs in the three-level neutral line of the power converter, it is necessary to determine the first-order change of the first current at each sampling moment based on the first current collected at each sampling moment. Specifically, Figure 4 As shown, for n sampling times t0…t n , the sampling resistors R0-R3 are at t0…t n The first current at the moment is Among them, since R0 and R3 are virtual auxiliary sampling points and do not exist in the actual circuit, and The value of is set to zero.

[0043] Specifically, the first-order change of the first current collected at any sampling time can be determined as:

[0044]

[0045] S303 , for any sampling moment, based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment, determine the second-order change of the first current collected at the sampling moment.

[0046] Here, in order to ensure the accuracy of determining the unbalanced current of the neutral line, after determining the first-order change of the first current collected at any sampling moment, the second-order change of the first current collected at the sampling moment is determined according to the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment. Specifically, the second-order change of the first current collected at any sampling moment can be determined as:

[0047]

[0048] S304: For any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, it is determined that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

[0049] Here, if the first-order change of the first current collected by any first sampling module at any sampling moment is greater than the preset first-order change threshold, or the second-order change is greater than the preset second-order change threshold, it means that the three-level neutral line of the multi-channel three-level DCDC power converter has a drastic change of unbalanced current at the sampling moment, and then it can be determined that the switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

[0050] The preset first-order change threshold and the preset second-order change threshold are determined according to the number of branches of the power converter, the current passing through the input inductor when the power converter is working normally, and a proportional parameter determined according to an empirical value. Specifically, Figure 4 As shown, taking a three-way three-level DCDC power converter as an example, the sum of the conduction currents flowing through each branch is the inductor current flowing through the input inductor. It is known that the inductor current of the input inductor L1 is I L1 , the number of branches is 3, then the current at the midpoint of the single switch tube conduction is: I IGBT =I L1 / 3; According to the current I at the midpoint of the single-channel switch tube conduction IGBT and the first proportional parameter K determined according to the empirical value, and the preset first-order change threshold is determined as I th =I IGBT ×K; in the embodiment of the present application, K takes the empirical value of 0.3. Then according to the first-order change threshold I th and the second proportional coefficient K′ determined according to the empirical value, the preset second-order change threshold is determined as I′ th =I th ×K′; in the embodiment of the present application, K′ takes the empirical value of 0.5.

[0051] In this way, it is not necessary to install detection circuits at both ends of each switch tube, and the failure of the switch tube can be detected, which greatly reduces the circuit installation cost and improves the detection efficiency of the switch tube failure.

[0052] Furthermore, since the detection circuit is installed on the three-level neutral line, the current during detection will not flow through the switch tube. The switch tube fault detection method in the embodiment of the present application can also avoid the switch tube loss caused by the detection circuit current and increase the service life of the switch tube.

[0053] In a possible implementation manner, when the fault detection circuit includes only one detection resistor, after determining that the switch tubes of the multi-channel three-level DCDC power converter have an open circuit fault at the sampling moment, the fault detection method further includes:

[0054] Based on the current direction of the first current, a first target switch tube having a circuit breaker fault is determined.

[0055] Here, when the fault detection circuit includes only one detection resistor, that is, when the multi-channel three-level DCDC power converter has only two branches, after determining that there is a switch tube fault in the circuit, the location range of the switch tube that may have a fault can also be determined based on the current direction of the first current for repair and replacement.

[0056] Further, the determining of a first target switch tube having a circuit breaker fault based on the current direction of the first current includes:

[0057] Step a1, if the current direction of the first current is flowing from the first end of the detection resistor to the second end of the detection resistor, determine that the lower half-bridge switch tube connected to the first end of the detection resistor or the upper half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube with a circuit breaker fault.

[0058] Here, if the current direction of the first current is from the first end of the detection resistor to the second end of the detection resistor, such as Figure 4 As shown, taking the branches at both ends of the sampling resistor R1 as an example, if the direction of the first current is flowing from the X1 end to the X2 end, it means that there may be two situations of switch tube failure at this time: the first situation is that the switch tube Q11 is short-circuited, and the currents of the switch tubes Q1 and Q2 flow to the switch tube Q12 together; the second situation is that the switch tube Q2 is short-circuited, and the current of the switch tube Q1 flows to the switch tubes Q11 and Q12 at the same time. Therefore, it can be determined that the lower half-bridge switch tube connected to the first end of the detection resistor or the upper half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube with short-circuit failure.

[0059] Step a2: If the current direction of the first current is from the second end of the detection resistor to the first end of the detection resistor, determine that the upper half-bridge switch tube connected to the first end of the detection resistor or the lower half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube with a short circuit fault.

[0060] Here, if the current direction of the first current is from the second end of the detection resistor to the first end of the detection resistor, such as Figure 4As shown, taking the branches at both ends of the sampling resistor R1 as an example, if the direction of the first current is flowing from the X2 end to the X1 end, it means that there may be two situations of switch tube failure at this time: the first situation is that the switch tube Q12 is short-circuited, and the currents of the switch tubes Q1 and Q2 flow to the switch tube Q11 together; the second situation is that the switch tube Q1 is short-circuited, and the current of the switch tube Q2 flows to the switch tubes Q11 and Q12 at the same time. Therefore, it can be determined that the upper half-bridge switch tube connected to the first end of the detection resistor or the lower half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube with short-circuit failure.

[0061] In a possible implementation manner, when the fault detection circuit includes at least two detection resistors, after determining that the switch tubes of the multi-channel three-level DCDC power converter have an open circuit fault at the sampling moment, the fault detection method further includes:

[0062] Step b1, for the first detection resistor and the second detection resistor connected to the switch tube of the same target branch, based on the current direction and current magnitude of the first current corresponding to the first detection resistor and the second detection resistor, determine the position of the switch tube where the circuit breaker fault occurs relative to the target branch.

[0063] Here, when the fault detection circuit includes at least two detection resistors, that is, when the branches of the multi-channel three-level DCDC power converter are more than two, after determining that there is a switch tube fault in the circuit, the position of the faulty switch tube relative to the target branch can be accurately determined based on the current direction and current magnitude of the first current corresponding to the first detection resistor and the second detection resistor connected to the switch tube of the same target branch.

[0064] Step b2: determining a second target switch tube having a circuit breaker fault according to the position of the switch tube having a circuit breaker fault determined for each target branch relative to the target branch.

[0065] Here, by verifying the positions of the switch tubes with circuit breakage faults determined for each target branch relative to the target branch, the switch tube with circuit breakage fault, that is, the second target switch tube, can be finally determined for repair and replacement.

[0066] Further, the determining the position of the switch tube having the circuit breaker fault relative to the target branch based on the current direction and current magnitude of the first current corresponding to the first detection resistor and the second detection resistor includes:

[0067] Step c1: if the current directions of the first currents corresponding to the first detection resistor and the second detection resistor are both flowing into the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the upper half bridge of the target branch.

[0068] Here, if Figure 4 As shown, the branches connected to the detection resistor R1 and the detection resistor R2 are taken as the target branches. If the current directions of the first currents corresponding to the first detection resistor and the second detection resistor are both flowing into the target branch, that is, the current flows from X1 through R1 to X2, and at the same time from X3 through R2 to X2, it means that the switch tube Q2 of the upper half bridge of the target branch has a circuit breaker fault, and the currents of other branches flow into the switch tube Q12 of the lower half bridge of the target branch through the three-level neutral line, and then it is determined that the switch tube position with the circuit breaker fault is located in the upper half bridge of the target branch. Specifically, the overall judgment formula can be expressed as: If the above formula is established, it is determined that the switch tube Q2 of the upper half bridge of the target branch has an open circuit fault. Here, the judgment value 0 in the formula is the theoretical judgment value of the circuit in a theoretical state. In the actual application of the circuit, the actual judgment value is a very small value near 0. Its value can be specifically set according to the actual use of the circuit, and no specific restrictions are made here. The same applies to the following formulas, which will not be repeated in this article.

[0069] Step c2: if the current directions of the first currents corresponding to the first detection resistor and the second detection resistor are both flowing out of the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the lower half bridge of the target branch.

[0070] Here, if the current direction of the first current corresponding to the first detection resistor and the second detection resistor is both flowing out of the target branch, that is, the current flows from X2 through R1 to X1, and at the same time from X2 through R2 to X3, it means that the switch tube Q12 of the lower half bridge of the target branch has a circuit breaker fault, and the current of the switch tube Q2 of the upper half bridge of the target branch flows into the lower half bridge switch tubes Q11 and Q13 on both sides through the three-level neutral line, thereby determining that the switch tube position where the circuit breaker fault occurs is located in the lower half bridge of the target branch. Specifically, the overall judgment formula can be expressed as: If the above equation holds true, it is determined that the switch tube Q12 of the lower half bridge of the target branch has an open circuit fault.

[0071] Step c3: if the current direction of the first current corresponding to the first detection resistor is flowing into the target branch, the current direction of the first current corresponding to the second detection resistor is flowing out of the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the lower half bridge of any branch in the direction of the first detection resistor of the target branch.

[0072] Here, if the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, and the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, that is, the current flows from X1 through R1 into X2, and at the same time from X2 through R2 into X3, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it means that at this time, a circuit-breaking fault occurs in the lower half-bridge of any branch in the direction of the first detection resistor of the target branch. Specifically, the fault causes the current of the switch tube of the upper half-bridge of the faulty branch to flow into the target branch and the lower half-bridge switch tube of the branch in the direction of the second detection resistor of the target branch through the three-level neutral line. In this flow direction, since the three-level neutral line where the first detection resistor is located is used as the main line and the three-level neutral line where the second detection resistor is located is used as the branch, the first current corresponding to the first detection resistor will be greater than the first current corresponding to the second detection resistor, and then it can be determined that the position of the switch tube where the circuit-breaking fault occurs is located in the lower half-bridge of any branch in the direction of the first detection resistor of the target branch. Specifically, the overall judgment formula can be expressed as: If the above formula is established, it is determined that the switch tube where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the first detection resistor of the target branch.

[0073] Step c4: if the current direction of the first current corresponding to the first detection resistor is flowing into the target branch, the current direction of the first current corresponding to the second detection resistor is flowing out of the target branch, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the second detection resistor of the target branch.

[0074] Here, if the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, and the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, that is, the current flows from X1 through R1 into X2, and at the same time from X2 through R2 into X3, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it means that at this time, a circuit-breaking fault occurs in the upper half bridge of any branch in the direction of the second detection resistor of the target branch. Specifically, the fault causes the current of the switch tube of the upper half bridge of the branch in the direction of the first detection resistor of the target branch and the branch in the direction of the first detection resistor of the target branch to flow into the lower half bridge switch tube of the faulty branch through the three-level neutral line. In this flow direction, since the three-level neutral line where the first detection resistor is located is used as a branch and the three-level neutral line where the second detection resistor is located is used as a trunk line, the first current corresponding to the first detection resistor will be less than the first current corresponding to the second detection resistor, and then it can be determined that the position of the switch tube where the circuit-breaking fault occurs is located in the upper half bridge of any branch in the direction of the second detection resistor of the target branch. Specifically, the overall judgment formula can be expressed as: If the above formula is established, it is determined that the switch tube where the circuit breaker fault occurs is located at the upper half bridge of any branch in the direction of the second detection resistor of the target branch.

[0075] Step c5: if the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is smaller than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the lower half bridge of any branch in the direction of the second detection resistor of the target branch.

[0076] Here, if the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, and the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, that is, the current flows from X2 through R1 into X1, and at the same time flows from X3 through R2 into X2, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it means that at this time, a circuit-breaking fault occurs in the lower half bridge of any branch in the direction of the second detection resistor of the target branch. Specifically, the fault causes the current of the switch tube of the upper half bridge of the faulty branch to flow into the target branch and the lower half bridge switch tube of the branch in the direction of the first detection resistor of the target branch through the three-level neutral line. In this flow direction, since the three-level neutral line where the first detection resistor is located is used as a branch and the three-level neutral line where the second detection resistor is located is used as a trunk line, the first current corresponding to the first detection resistor will be less than the first current corresponding to the second detection resistor, and then it can be determined that the position of the switch tube where the circuit-breaking fault occurs is located in the lower half bridge of any branch in the direction of the second detection resistor of the target branch. Specifically, the overall judgment formula can be expressed as: If the above formula is established, it is determined that the switch tube where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the second detection resistor of the target branch.

[0077] Step c6: If the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the first detection resistor of the target branch.

[0078] Here, if the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, and the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, that is, the current flows from X2 through R1 into X1, and at the same time flows from X3 through R2 into X2, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it means that at this time, a circuit-breaking fault occurs in the upper half bridge of any branch in the direction of the first detection resistor of the target branch. Specifically, the fault causes the current of the switch tube of the upper half bridge of the target branch and the second detection resistor direction of the target branch to flow into the lower half bridge switch tube of the faulty branch through the three-level neutral line. In this flow direction, since the three-level neutral line where the first detection resistor is located is used as the main line and the three-level neutral line where the second detection resistor is located is used as the branch, the first current corresponding to the first detection resistor will be greater than the first current corresponding to the second detection resistor, and then it can be determined that the position of the switch tube where the circuit-breaking fault occurs is located in the upper half bridge of any branch in the direction of the first detection resistor of the target branch. Specifically, the overall judgment formula can be expressed as: If the above formula is established, it is determined that the switch tube where the circuit breaker fault occurs is located at the upper half bridge of any branch in the direction of the first detection resistor of the target branch.

[0079] Furthermore, the fault detection method further includes:

[0080] For any sampling moment, if the second-order change of the first current collected by any of the first sampling modules is greater than a preset second second-order change threshold, it is determined that the switch tubes of the upper and lower half bridges of the multi-channel three-level DCDC power converter have short-circuit faults at the sampling moment.

[0081] Here, when the switch tubes of the upper and lower half bridges are short-circuited, the input inductor L1 will quickly saturate, causing the input and output to short-circuit. Since the switch tube is not controlled, the power converter will quickly explode. Therefore, the embodiment of the present application detects the overcurrent change in the three-level neutral line to quickly cut off the circuit before the explosion to ensure safety. Specifically, in order to increase the detection sensitivity, the second-order change of the detection resistor current is used as the judgment basis. If the second-order change of the first current collected by any first sampling module is greater than the preset second second-order change threshold, it is determined that the switch tubes of the upper and lower half bridges of the multi-channel three-level DCDC power converter have short-circuit faults at the sampling moment, wherein the second second-order change threshold is greater than the first second-order change threshold.

[0082] In a preferred solution of the embodiment of the present application, the fault detection method further includes:

[0083] Step d1, based on a second preset sampling frequency, collecting a first voltage between a three-level positive bus and a three-level neutral line and a second voltage between a three-level neutral line and a three-level negative bus collected by the second sampling module.

[0084] Here, the fault detection circuit can also detect whether a short circuit fault occurs in the switch tubes of the upper and lower half bridges. Specifically, the second sampling module performs voltage sampling at the moment when the PWM controls each switch tube to be turned off, and collects the first voltage between the three-level positive bus and the three-level neutral line and the second voltage between the three-level neutral line and the three-level negative bus collected by the second sampling module. The second preset sampling frequency is set to a frequency that enables each second sampling module to perform sampling at the midpoint of the shutdown of each switch tube driven by PWM.

[0085] Step d2: for any second sampling moment, if the first voltage is zero, it is determined that the switch tube of the upper half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment.

[0086] Here, if the first voltage is zero, it is determined that the switch tubes of the upper half bridges of the multi-channel three-level DCDC power converter have a short circuit fault at the second sampling moment.

[0087] Step d3: for any second sampling moment, if the second voltage is zero, it is determined that the switch tube of the lower half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment.

[0088] Here, if the second voltage is zero, it is determined that the switch tube of the lower half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment.

[0089] The embodiment of the present application provides a fault detection method for a switch tube, which is applied to a calculation module of a fault detection device for a switch tube, wherein the fault detection device further includes a fault detection circuit, wherein the fault detection circuit includes at least one detection resistor and a first sampling module corresponding to the detection resistor; any detection resistor is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any detection resistor is electrically connected to the input end of the corresponding first sampling module; the output end of each first sampling module is electrically connected to the calculation module respectively; the fault detection method includes: based on a preset sampling frequency, collecting a first current collected by each first sampling module; the first current is a current flowing through the detection resistor corresponding to the first sampling module; For any sampling moment, based on the first current collected at the sampling moment and the first current collected at the previous sampling moment, the first-order change of the first current collected at the sampling moment is determined; for any sampling moment, based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment, the second-order change of the first current collected at the sampling moment is determined; for any sampling moment, if the first-order change of the first current collected by any first sampling module is greater than the preset first-order change threshold, or the second-order change of the first current collected by any first sampling module is greater than the preset second-order change threshold, it is determined that the switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment. In this way, by detecting the balance degree of the three-level neutral line current of the switch tube, it is determined whether the switch tube has a fault, and the detection efficiency of the switch tube fault detection is improved.

[0090] Based on the same application concept, a calculation module corresponding to the fault detection method of the switch tube provided in the above embodiment is also provided in the embodiment of the present application. Since the principle of solving the problem by the calculation module in the embodiment of the present application is similar to the fault detection method of the switch tube in the above embodiment of the present application, the implementation of the calculation module can refer to the implementation of the method, and the repeated parts will not be repeated.

[0091] See also Figure 5 , Figure 5 This is one of the functional module diagrams of a computing module provided in an embodiment of the present application, such as Figure 5 As shown, the calculation module 130 includes:

[0092] The sampling unit 131 is used to collect the first current collected by each first sampling module based on a preset sampling frequency; the first current is the current flowing through the detection resistor corresponding to the first sampling module.

[0093] The first determining unit 132 is configured to determine, at any sampling moment, a first-order change of the first current collected at the sampling moment based on the first current collected at the sampling moment and the first current collected at the previous sampling moment.

[0094] The second determining unit 133 is used to determine, at any sampling moment, a second-order change of the first current collected at the sampling moment based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment.

[0095] The judgment unit 134 is used to determine that, for any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

[0096] In a possible implementation manner, when the fault detection circuit includes only one detection resistor, after the judgment unit 134 is used to determine that the switch tubes of the multi-channel three-level DCDC power converter have a circuit breaker fault at the sampling moment, the judgment unit 134 is further used to:

[0097] Based on the current direction of the first current, a first target switch tube having a circuit breaker fault is determined.

[0098] Further, when the judging unit 134 is used to determine the first target switch tube having a circuit breaker fault based on the current direction of the first current, the judging unit 134 is specifically used to:

[0099] If the current direction of the first current is flowing from the first end of the detection resistor to the second end of the detection resistor, determining that the lower half-bridge switch connected to the first end of the detection resistor or the upper half-bridge switch connected to the second end of the detection resistor is the first target switch having a circuit breaker fault;

[0100] If the current direction of the first current is from the second end of the detection resistor to the first end of the detection resistor, determine that the upper half-bridge switch tube connected to the first end of the detection resistor or the lower half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube where a circuit breaker fault occurs.

[0101] In a possible implementation manner, when the fault detection circuit includes at least two detection resistors, after the judgment unit 134 is used to determine that the switch tubes of the multi-channel three-level DCDC power converter have a circuit breaker fault at the sampling moment, the judgment unit 134 is further used to:

[0102] For a first detection resistor and a second detection resistor connected to a switch tube of the same target branch, based on the current direction and current magnitude of a first current corresponding to the first detection resistor and the second detection resistor, determine the position of the switch tube having a circuit breaker fault relative to the target branch;

[0103] According to the positions of the switch tubes with the circuit breaking fault determined for each of the target branches relative to the target branch, a second target switch tube with the circuit breaking fault is determined.

[0104] Further, when the judgment unit 134 is used to determine the position of the switch tube having the circuit breaker fault relative to the target branch based on the current direction and current magnitude of the first current corresponding to the first detection resistor and the second detection resistor, the judgment unit 134 is specifically used to:

[0105] If the current directions of the first current corresponding to the first detection resistor and the second detection resistor are both to flow into the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the upper half bridge of the target branch;

[0106] If the current directions of the first current corresponding to the first detection resistor and the second detection resistor are both flowing out of the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the lower half bridge of the target branch;

[0107] If the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the first detection resistor of the target branch;

[0108] If the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the second detection resistor of the target branch;

[0109] If the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the second detection resistor of the target branch;

[0110] If the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the first detection resistor of the target branch.

[0111] Furthermore, the calculation module 130 also includes:

[0112] The second judgment unit 135 is used to determine that the switch tubes of the upper and lower half bridges of the multi-channel three-level DCDC power converter have short-circuit faults at any sampling moment if the second-order change of the first current collected by any of the first sampling modules is greater than a preset second second-order change threshold.

[0113] In a preferred solution of the embodiment of the present application, the calculation module 130 further includes:

[0114] The second sampling unit 136 is used to collect the first voltage between the three-level positive bus and the three-level neutral line and the second voltage between the three-level neutral line and the three-level negative bus collected by the second sampling module based on a second preset sampling frequency.

[0115] The third judgment unit 137 is used for determining, for any second sampling moment, if the first voltage is zero, that the switch tube of the upper half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment.

[0116] The fourth judgment unit 138 is used to determine that, for any second sampling moment, if the second voltage is zero, a short circuit fault exists in the switch tube of the lower half bridge of the multi-channel three-level DCDC power converter at the second sampling moment.

[0117] The embodiment of the present application provides a calculation module, which is applied to a fault detection device for a switch tube. The fault detection device also includes a fault detection circuit, which includes at least one detection resistor and a first sampling module corresponding to the detection resistor; any detection resistor is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any detection resistor is electrically connected to the input end of the corresponding first sampling module; the output end of each first sampling module is electrically connected to the calculation module respectively; the calculation module includes: an adopting unit, which is used to collect the first current collected by each first sampling module based on a preset sampling frequency; the first current is the current flowing through the detection resistor corresponding to the first sampling module; a first determining unit, which is used for any sampling At a given moment, based on the first current collected at the given sampling moment and the first current collected at the previous sampling moment, determine the first-order change of the first current collected at the given sampling moment; a second determination unit is used to determine the second-order change of the first current collected at the given sampling moment based on the first-order change of the first current collected at the given sampling moment and the first-order change of the first current collected at the previous sampling moment for any given sampling moment; a judgment unit is used to determine that at any given sampling moment, if the first-order change of the first current collected by any first sampling module is greater than a preset first-order change threshold, or the second-order change of the first current collected by any first sampling module is greater than a preset second-order change threshold, the switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the given sampling moment. In this way, by detecting the balance degree of the three-level neutral line current of the switch tube, it is determined whether the switch tube has a fault, thereby improving the detection efficiency of the switch tube fault detection.

[0118] Based on the same application idea, please refer to Figure 7 , Figure 7 A schematic diagram of the structure of an electronic device 700 provided in an embodiment of the present application includes: a processor 710, a memory 720 and a bus 730.

[0119] The memory 720 stores machine-readable instructions executable by the processor 710. When the electronic device 700 is running, the processor 710 communicates with the memory 720 through the bus 730. When the processor 710 is running, the machine-readable instructions are executed by the steps of the switch tube fault detection method provided in the above embodiment. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0120] Based on the same application concept, an embodiment of the present application also provides 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 switch tube fault detection method provided in the above embodiment are executed. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0121] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0122] In the embodiments provided in the present application, it should be understood that the disclosed methods, modules and devices can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0123] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0124] In addition, each functional unit in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0125] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0126] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0127] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. They should all be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for detecting a fault of a switching tube, characterized in that: A calculation module applied to a fault detection device for a switch tube, wherein the fault detection device further comprises a fault detection circuit, wherein the fault detection circuit comprises at least one detection resistor and a first sampling module corresponding to the detection resistor; any of the detection resistors is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any of the detection resistors is electrically connected to the input end of the corresponding first sampling module; The output ends of the first sampling modules are electrically connected to the calculation modules respectively; The fault detection method comprises: Based on a preset sampling frequency, the first current collected by each first sampling module is collected; the first current is the current flowing through the detection resistor corresponding to the first sampling module; For any sampling moment, based on the first current collected at the sampling moment and the first current collected at the previous sampling moment, determine a first-order change of the first current collected at the sampling moment; For any sampling moment, based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment, determine the second-order change of the first current collected at the sampling moment; For any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, it is determined that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

2. The fault detection method according to claim 1, characterized in that: When the fault detection circuit includes only one detection resistor, after determining that the switch tubes of the multi-channel three-level DCDC power converter have an open circuit fault at the sampling time, the fault detection method further includes: Based on the current direction of the first current, a first target switch tube having a circuit breaker fault is determined.

3. The fault detection method according to claim 2, characterized in that: The step of determining a first target switch tube having a circuit breaker fault based on the current direction of the first current includes: If the current direction of the first current is flowing from the first end of the detection resistor to the second end of the detection resistor, determining that the lower half-bridge switch connected to the first end of the detection resistor or the upper half-bridge switch connected to the second end of the detection resistor is the first target switch having a circuit breaker fault; If the current direction of the first current is from the second end of the detection resistor to the first end of the detection resistor, determine that the upper half-bridge switch tube connected to the first end of the detection resistor or the lower half-bridge switch tube connected to the second end of the detection resistor is the first target switch tube where a circuit breaker fault occurs.

4. The fault detection method according to claim 1, characterized in that: When the fault detection circuit includes at least two detection resistors, after determining that the switch tubes of the multi-channel three-level DCDC power converter have an open circuit fault at the sampling time, the fault detection method further includes: For a first detection resistor and a second detection resistor connected to a switch tube of the same target branch, based on the current direction and current magnitude of a first current corresponding to the first detection resistor and the second detection resistor, determine the position of the switch tube having a circuit breaker fault relative to the target branch; According to the positions of the switch tubes with the circuit breaking fault determined for each of the target branches relative to the target branch, a second target switch tube with the circuit breaking fault is determined.

5. The fault detection method according to claim 4, characterized in that: The determining the position of the switch tube having the circuit breaker failure relative to the target branch based on the current direction and current magnitude of the first current corresponding to the first detection resistor and the second detection resistor includes: If the current directions of the first current corresponding to the first detection resistor and the second detection resistor are both to flow into the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the upper half bridge of the target branch; If the current directions of the first current corresponding to the first detection resistor and the second detection resistor are both flowing out of the target branch, it is determined that the switch tube where the circuit breaker fault occurs is located at the lower half bridge of the target branch; If the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the first detection resistor of the target branch; If the current direction of the first current corresponding to the first detection resistor is to flow into the target branch, the current direction of the first current corresponding to the second detection resistor is to flow out of the target branch, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the second detection resistor of the target branch; If the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is less than the first current corresponding to the second detection resistor, it is determined that the switch tube position where the circuit breaker fault occurs is located at the lower half bridge of any branch in the direction of the second detection resistor of the target branch; If the current direction of the first current corresponding to the first detection resistor is to flow out of the target branch, the current direction of the first current corresponding to the second detection resistor is to flow into the target branch, and the first current corresponding to the first detection resistor is greater than the first current corresponding to the second detection resistor, it is determined that the position of the switch tube where the circuit breaker fault occurs is located in the upper half bridge of any branch in the direction of the first detection resistor of the target branch.

6. The fault detection method according to claim 1, characterized in that: The fault detection method further comprises: For any sampling moment, if the second-order change of the first current collected by any of the first sampling modules is greater than a preset second second-order change threshold, it is determined that the switch tubes of the upper and lower half bridges of the multi-channel three-level DCDC power converter have short-circuit faults at the sampling moment.

7. The fault detection method according to claim 1, characterized in that: The fault detection circuit also includes a second sampling module; the input end of the second sampling module is electrically connected to the three-level positive bus, the three-level neutral line and the three-level negative bus of the multi-channel three-level DCDC power converter respectively; The output end of the second sampling module is electrically connected to the calculation module; The fault detection method further comprises: Based on a second preset sampling frequency, collecting a first voltage between the three-level positive bus and the three-level neutral line and a second voltage between the three-level neutral line and the three-level negative bus collected by the second sampling module; For any second sampling moment, if the first voltage is zero, it is determined that the switch tube of the upper half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment; For any second sampling moment, if the second voltage is zero, it is determined that the switch tube of the lower half bridge of the multi-channel three-level DCDC power converter has a short circuit fault at the second sampling moment.

8. A computing module, characterized in that: A fault detection device applied to a switch tube, the fault detection device further comprising a fault detection circuit, the fault detection circuit comprising at least one detection resistor and a first sampling module corresponding to the detection resistor; any of the detection resistors is located on the three-level neutral line of two adjacent switch tubes in a multi-channel three-level DCDC power converter; any of the detection resistors is electrically connected to the input end of the corresponding first sampling module; The output ends of the first sampling modules are electrically connected to the calculation modules respectively; The calculation module comprises: A sampling unit, configured to collect the first current collected by each first sampling module based on a preset sampling frequency; the first current is the current flowing through the detection resistor corresponding to the first sampling module; A first determining unit is used to determine, for any sampling moment, a first-order change of the first current collected at the sampling moment based on the first current collected at the sampling moment and the first current collected at the previous sampling moment; A second determining unit is used to determine, for any sampling moment, a second-order change of the first current collected at the sampling moment based on the first-order change of the first current collected at the sampling moment and the first-order change of the first current collected at the previous sampling moment; A judgment unit is used to determine, for any sampling moment, if a first-order change of the first current collected by any of the first sampling modules is greater than a preset first-order change threshold, or a second-order change of the first current collected by any of the first sampling modules is greater than a preset second-order change threshold, that a switch tube of the multi-channel three-level DCDC power converter has a circuit breaker fault at the sampling moment.

9. A fault detection device for a switching tube, characterized in that: The fault detection device comprises: A fault detection circuit and a computing module as claimed in claim 8.

10. A power converter, characterized in that: A fault detection device for a switching tube comprising the method according to claim 9.

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