Fault determination apparatus and method for three-phase dual active bridge converter, and electronic device

Abstract

A fault determination apparatus and method for a three-phase dual active bridge converter, and an electronic device. The fault determination apparatus comprises a signal collection module and a processing module. The signal collection module is connected to three bridge-arm neutral points on a primary side of a three-phase dual active bridge converter, and the signal collection module is configured to collect the neutral-to-neutral voltage between every two bridge-arm neutral points on the primary side of the three-phase dual active bridge converter. The processing module is connected to the signal collection module, and the processing module is configured to determine, on the basis of the relative relationship between a sequence variation of the neutral-to-neutral voltage and a normal sequence variation, whether a fault has occurred in the three-phase dual active bridge converter.

Description

Fault diagnosis device, method and electronic equipment for three-phase dual-active bridge converter Technical Field

[0001] Embodiments of the present application relate to power conversion technology, for example, to a fault diagnosis device, method, and electronic device for a three-phase dual-active bridge converter. Background Art

[0002] The development of electronic devices is trending towards miniaturization, cost-effectiveness, and multifunctionality, ushering in a new era of electronic devices. As the core power supply component of electronic devices, the performance of DC converters is crucial to the reliability of electronic devices and the safety of operators.

[0003] The fault diagnosis solutions for DC converters in related technologies all use sensors to detect fault characteristic parameters. However, the sensor-based diagnosis method increases the complexity of the power supply components and slows down the diagnosis speed.

[0004] Summary of the Invention

[0005] The present application provides a fault judgment device, method and electronic equipment for a three-phase dual-active bridge converter, thereby avoiding the processing of a large amount of sensor data and improving the judgment speed.

[0006] In a first aspect, an embodiment of the present application provides a fault judgment device for a three-phase dual-active bridge converter, the device comprising a signal acquisition module and a processing module; the signal acquisition module is respectively connected to the neutral points of the three bridge arms on the primary side of the three-phase dual-active bridge converter, and the signal acquisition module is configured to collect the neutral point voltage between the neutral points of every two bridge arms on the primary side of the three-phase dual-active bridge converter; the processing module is connected to the signal acquisition module, and the processing module is configured to determine whether the three-phase dual-active bridge converter has a fault based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change.

[0007] Optionally, the signal acquisition module includes a preprocessing unit corresponding one-to-one to the neutral point voltage and an analog-to-digital conversion unit corresponding one-to-one to the neutral point voltage; the preprocessing unit is configured to obtain the corresponding analog signal of the neutral point voltage and preprocess the analog signal; the analog-to-digital conversion unit is respectively connected to the corresponding preprocessing unit and the processing module, and the analog-to-digital conversion unit is configured to convert the preprocessed analog signal of the neutral point voltage into a digital signal and send the digital signal to the processing module.

[0008] Optionally, the processing module is further configured to determine the fault location of the three-phase dual-active bridge converter according to the relative relationship between the sequence change of the neutral point voltage and the fault sequence change when a fault occurs in the three-phase dual-active bridge converter, wherein the fault sequence change corresponds to the controllable switch where the fault occurs.

[0009] In the second aspect, an embodiment of the present application also provides a fault judgment method for a three-phase dual-active bridge converter, the fault judgment method including: obtaining the neutral point voltage between the neutral points of each two bridge arms on the primary side of the three-phase dual-active bridge converter; and determining whether the three-phase dual-active bridge converter has a fault based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change.

[0010] Optionally, determining whether the three-phase dual-active bridge converter has a fault is performed based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, including: determining that the three-phase dual-active bridge converter has a fault when the sequence of the neutral point voltage does not change according to the normal sequence change; and determining that the three-phase dual-active bridge converter is operating normally when the sequence of the neutral point voltage changes according to the normal sequence change.

[0011] Optionally, the neutral point voltage includes the voltage of the first and second bridge arms, the voltage of the second and third bridge arms, and the voltage of the third and first bridge arms; before determining the fault occurrence of the three-phase dual-active bridge converter based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, it also includes: preprocessing and analog-to-digital conversion processing of the analog signals of the first and second bridge arm voltages, the analog signals of the second and third bridge arm voltages, and the analog signals of the third and first bridge arm voltages, respectively, to generate digital signals of the first and second bridge arm voltages, digital signals of the second and third bridge arm voltages, and digital signals of the third and first bridge arm voltages.

[0012] Optionally, the preprocessing includes attenuation processing, filtering processing and isolation processing.

[0013] Optionally, the normal sequence change includes: the sequential combination of the one-two bridge arm voltage, the two-three bridge arm voltage and the three-one bridge arm voltage changes from high-low-zero to high-zero-low, then from high-zero-low to zero-high-low, then from zero-high-low to low-high-zero, then from low-high-zero to low-zero-high, then from low-zero-high to zero-low-high, then from zero-low-high back to high-low-zero and cycle.

[0014] Optionally, after determining the fault occurrence of the three-phase dual-active bridge converter based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, it also includes: when a fault occurs in the three-phase dual-active bridge converter, locating the faulty controllable switch based on the corresponding relationship between the subsequent sequence change of the neutral point voltage and the fault sequence change.

[0015] In a third aspect, an embodiment of the present application further provides an electronic device, comprising: at least one processing module; and a memory communicatively connected to the at least one processing module; wherein the memory stores a computer program executable by the at least one processing module, and the computer program is executed by the at least one processing module so that the at least one processing module can execute the fault judgment method of the three-phase dual-active bridge converter described in any one of the second aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic diagram of a three-phase dual-active bridge converter and a fault diagnosis device thereof provided in an embodiment of the present application;

[0017] FIG2 is a schematic diagram showing changes in state data of a three-phase dual-active bridge converter under normal working conditions provided by an embodiment of the present application;

[0018] FIG3 is a schematic diagram of a normal sequence change of the neutral point voltage provided by an embodiment of the present application;

[0019] FIG4 is a schematic diagram showing changes in the states of multiple controllable switches on the primary side during a cycle according to an embodiment of the present application;

[0020] FIG5 is a schematic diagram showing changes in state data of a three-phase dual-active bridge converter in a normal-to-fault working state provided by an embodiment of the present application;

[0021] FIG6 is a schematic diagram showing the change in state of multiple controllable switches on the primary side after normal operation is switched to a fault state according to an embodiment of the present application;

[0022] FIG7 is a diagram showing a sequence of changes in the neutral point voltage from normal to fault conditions provided by an embodiment of the present application;

[0023] FIG8 is a schematic diagram of the composition of another fault judgment device for a three-phase dual-active bridge converter provided in an embodiment of the present application;

[0024] FIG9 is a circuit diagram of a group of pre-processing units and their corresponding analog-to-digital conversion circuits in a signal acquisition module provided by an embodiment of the present application;

[0025] FIG10 is another state diagram of the sequence change of the neutral point voltage from normal to fault provided by an embodiment of the present application;

[0026] FIG11 is a waveform diagram of a control signal of a first controllable switch and voltages between three neutral points during normal operation provided by an embodiment of the present application;

[0027] FIG12 is a waveform diagram of the control signal of the first controllable switch and the voltage between the three neutral points when the first controllable switch fails;

[0028] FIG13 is a waveform diagram of the control signal of the first controllable switch, the input signal of the signal acquisition module, and the output signal when the first controllable switch fails;

[0029] FIG14 is a waveform diagram of multiple signals of a three-phase dual-active bridge converter and a fault diagnosis device thereof provided in an embodiment of the present application;

[0030] FIG15 is an amplified waveform diagram of multiple signals of a three-phase dual-active bridge converter and a fault diagnosis device thereof provided in an embodiment of the present application;

[0031] FIG16 is a flow chart of a fault determination method for a three-phase dual-active bridge converter provided by the present application;

[0032] FIG17 is a flow chart of another method for determining a fault of a three-phase dual-active bridge converter according to an embodiment of the present application;

[0033] FIG18 shows a schematic structural diagram of an electronic device that can be used to implement an embodiment of the present application. DETAILED DESCRIPTION

[0034] The present application is described below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are intended only to explain the present application and are not intended to limit the present application. It should also be noted that, for ease of description, only the structures relevant to the present application are shown in the accompanying drawings.

[0035] The present application provides a fault diagnosis device for a three-phase dual-active bridge converter. FIG1 is a schematic diagram of the components of a three-phase dual-active bridge converter and its fault diagnosis device provided by the present application. Referring to FIG1 , the fault diagnosis device 100 for the three-phase dual-active bridge converter includes a signal acquisition module 114 and a processing module 113. The signal acquisition module 114 is respectively connected to the three bridge arm neutral points A, B, and C on the primary side of the three-phase dual-active bridge converter 101. The signal acquisition module 114 is configured to collect the neutral point voltage 112 between the neutral points of each two bridge arms on the primary side 102 of the three-phase dual-active bridge converter 101. The processing module 113 is connected to the signal acquisition module 114. The processing module 113 is configured to determine the occurrence of a fault in the three-phase dual-active bridge converter 101 based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change.

[0036] The three-phase dual-active bridge converter 101 is provided with a primary-side bridge 102, a capacitor assembly 109, a transformer assembly 110, and a secondary-side bridge 103. Both the primary-side bridge 102 and the secondary-side bridge 103 are provided with three bridge arm branches, each branch including two switch assemblies 104. Each switch assembly 104 is provided with a controllable switch 106 and an anti-reverse polarity diode 108 connected in parallel, as well as a parasitic capacitor 108. The processing module 113 is connected to the multiple controllable switches 106 and issues control signals as needed to control the switching of the multiple controllable switches 106 to achieve conversion of the primary-side output DC power.

[0037] The bridge arm neutral point refers to the connection point between the two switch combinations 104 on the primary side bridge arm of the three-phase dual-active bridge converter 101. The primary side of the three-phase dual-active bridge converter 101 is provided with three bridge arms, which can be defined as the first bridge arm, the second bridge arm, and the third bridge arm, respectively. The bridge arm combinations can be 1-2, 2-3, and 3-1, respectively. The signal acquisition module 114 refers to the signal acquisition and processing component of the neutral point voltage 112. The neutral point voltage 112 includes the first bridge arm neutral point A and the second bridge arm neutral point B. AB , the voltage between the second bridge arm neutral point B and the third bridge arm neutral point C is V BC , and the voltage V between the neutral point C of the third bridge arm and the neutral point A of the first bridge arm CA The signal acquisition module 114 is connected to the neutral points A, B and C of the three bridge arm branches on the primary side of the three-phase dual active bridge converter 101, and can collect the voltage V AB , the voltage of the second and third bridge arms V BC and the Sany bridge arm voltage V CA And perform data preprocessing.

[0038] The processing module 113 can determine whether the three-phase dual-active bridge converter has a fault based on the sequence changes of the three neutral point voltages of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages collected by the signal acquisition module. The sequence of the three neutral point voltages refers to the sequence of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages arranged in sequence. For example, if in a normal sequence change, the sequence combination of the three neutral point voltages of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages is high zero low (that is, the first and second bridge arm voltages are high potential, the second and third bridge arm voltages are zero potential, and the third and first bridge arm voltages are low potential), the next step should be to change to zero high low. In the actual sequence change, if the sequence combination of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages changes from high zero low to low high zero, then the processing module can determine that the three-phase dual-active bridge converter has a fault. The normal sequence variation of the neutral point voltage is related to the variation of the control signals output by the processing module to the multiple controllable switches.

[0039] FIG2 is a schematic diagram of the change of state data of a three-phase dual-active bridge converter under normal working conditions provided by an embodiment of the present application. The state data includes control signals of multiple controllable switches, neutral point voltages, and sequences of neutral point voltages. In conjunction with FIG1 and FIG2, on the one hand, S 11 、S 12 、S 13 、S 14 、S 15 and S 16 The six control signals 111 outputted by the processing module 113 to the primary side are applied to the first controllable switch T in the primary side bridge 102 in a one-to-one correspondence. 11 , the second controllable switch T 12 , the third controllable switch T 13 , the fourth controllable switch T 14 , the fifth controllable switch T 15 and the sixth controllable switch T 16 The control terminals of the six controllable switches 106 are S 21 、S 22 、S 23 、S 24 、S 25 and S 26 The six control signals output by the processing module 113 to the secondary side are applied one by one to the seventh controllable switch T in the secondary side bridge. 21 , the eighth controllable switch T 22 , the ninth controllable switch T 23 , the tenth controllable switch T 24 , the eleventh controllable switch T 25 and the twelfth controllable switch T 26The control terminals of these six controllable switches 106. The controllable switches 106 in each branch operate in an efficient and highly complementary mode, with each branch of the primary-side bridge 102 and the secondary-side bridge 103 lagging the previous branch by 120 degrees. The voltage on the second bridge arm lags 120 degrees behind the first bridge arm; the voltage on the third bridge arm lags 120 degrees behind the second bridge arm and 240 degrees behind the first bridge arm. To transfer power from the primary to the secondary side, the control signal on the secondary side increases the phase shift by a preset angle compared to the control signal on the primary side. A negative phase shift can be applied to the opposite power flow (not shown).

[0040] Voltage of bridge arm 1 and 2 V AB It is the differential voltage at the neutral point A of the first bridge arm branch relative to the neutral point B of the second bridge arm branch. BC is the differential voltage at the neutral point B of the second bridge arm relative to the neutral point C of the third bridge arm. The voltage V CA It is the differential voltage between the neutral point C of the third bridge arm branch and the neutral point A of the first bridge arm branch. The voltage between the three neutral points V AB 、V BC and V CA It moves between a high potential +ve, a low potential −ve and a zero potential N, and the value it takes is related to the state of the controllable switch 106 .

[0041] In the normal state of the three-phase dual active bridge converter 101, the three switch node voltages V AB 、V BC and V CA Cannot share the same level at the same time, and the voltage V between the three neutral points at the same time AB 、V BC and V CA If the voltage between the three neutral points is expressed in a specific order and the control signal switches normally, V AB 、V BC and V CA The sequence will repeat after one switching cycle. According to the change of the control signal, a single switching cycle can be divided into six time intervals or states. T0, T1, T2, T3, T4, T5 and T6 represent the six moments in one switching cycle. In each time subinterval, the voltage V AB 、V BC and V CA The three-phase dual active bridge converter 101 never shows the same voltage level. In normal state, the neutral point voltage V AB 、V BC and V CA The sequence repeats after each switching cycle.

[0042] For example, FIG3 is a schematic diagram of a normal sequence change of the neutral point voltage provided by an embodiment of the present application, and FIG4 is a schematic diagram of a change in the state of multiple controllable switches on the primary side during a cycle provided by an embodiment of the present application. FIG3 illustrates the cycle process of the neutral point voltage in the form of a voltage line diagram and a cycle block diagram, and FIG4 shows the on-off state and current direction of multiple controllable switches on the primary side corresponding to multiple time intervals in FIG3. Combined with FIG2, FIG3 and FIG4, between the initial moment T0 and the first moment T1, the sequence of the neutral point voltage is high, low and zero, that is, the first and second bridge arm voltages V AB =High potential +ve, voltage of the second and third bridge arms V BC is low potential -ve and the voltage of the three-bridge arm V CA The voltage between the neutral points is high, zero and low, that is, the voltage between the first and second bridge arms V AB =High potential +ve, the voltage of the second and third bridge arms V BC is the zero potential N, the voltage of the Sanyi bridge arm V CA Between the second moment T2 and the third moment T3, the sequence of the voltage between the neutral points is zero high low, that is, the voltage of the first and second bridge arms V AB is the zero potential N, the voltage of the second and third bridge arms V BC =High potential +ve, Sany bridge arm voltage V CA Between the third moment T3 and the fourth moment T4, the voltage sequence between the neutral points is low, high and zero, that is, the voltage of the first and second bridge arms V AB is low potential -ve, the voltage of the second and third bridge arms V bc =High potential +ve, Sany bridge arm voltage V CA The voltage between the neutral points is low, zero and high, that is, the voltage between the first and second bridge arms V AB is low potential -ve, the voltage of the second and third bridge arms V BC is the zero potential N, the voltage of the Sanyi bridge arm V CA =High potential +ve. Between the fifth moment T5 and the sixth moment T6, the sequence of the voltage between the neutral points is zero, low and high, that is, the voltage of the first and second bridge arms V AB is the zero potential N, the voltage of the second and third bridge arms V BC is low potential -ve, the voltage of the Sany bridge arm V CA =High potential +ve. This completes a normal sequence change cycle, which is then repeated. The inductor current and neutral point voltage corresponding to the six time intervals during one cycle are shown in Table 1.

[0043] Table 1 Cyclic data table of normal sequence changes of neutral point voltage

[0044] In summary, when power is transmitted from the primary side to the secondary side, the normal sequence of changes in the neutral point voltage includes transitioning from high-low-zero to high-zero-low, to zero-high-low, to low-high-zero, to low-zero-high, to zero-low-high, and then back to high-low-zero, and so on. Therefore, the processing module can store data on the normal sequence of changes in the neutral point voltage. If it is determined that the sequence of changes in the neutral point voltage does not match the normal sequence, it can be determined that a fault has occurred in the three-phase dual-active bridge converter. In addition, when power is transmitted in the reverse direction from the secondary side to the primary side, the neutral point voltage also exhibits a normal sequence of changes based on the control signal output by the processing module. Examples are not provided here.

[0045] Based on the normal sequence of changes in the neutral point voltage, the inventors conducted further research to explore the sequence of changes in the neutral point voltage when a three-phase dual-active bridge converter fails. In this application embodiment, a fault in the three-phase dual-active bridge converter is defined as an open-circuit fault in any controllable switch on the primary side of the three-phase dual-active bridge converter due to a fault in the converter itself or a fault in its drive circuit. During the research, both scenarios were simulated by stopping the control signal to the corresponding controllable switch. For ease of understanding, the following assumptions have been made: 1. Fault determination and fault location analysis were performed only for the three-phase dual-active bridge converter operating in forward mode. The same analysis is valid for reverse flow and will not be repeated here. 2. A fault is introduced into the controllable switch by stopping the control signal to the controllable switch. For example, if the controllable switch is a field-effect transistor, to simulate an open-circuit fault in the first controllable switch of the first bridge arm, the control signal supply to the first controllable switch of the first bridge arm can be stopped. 3. In the event of an open-circuit fault in a controllable switch, it is assumed that the anti-parallel diode and parasitic capacitor of the controllable switch are operating normally.

[0046] FIG5 is a schematic diagram of the change of state data of a three-phase dual-active bridge converter in a normal-to-fault working state provided by an embodiment of the present application, wherein the state data includes S 11 、S 12 、S 13 、S 14 、S 15 and S 16 The control signals 111 and the primary side i of the six controllable switches L1 、i L2 and i L3 The sequence of three inductor currents 115, neutral point voltage 112 and neutral point voltage, FIG6 is a schematic diagram of the change of the state of multiple controllable switches on the primary side after normal to fault according to an embodiment of the present application, combined with FIG1, FIG5 and FIG6, the first controllable switch T on the first bridge arm 11Taking an open circuit fault (OCF) as an example, the situation on the primary side after the fault is analyzed according to the definitions and assumptions of this embodiment to explain the changes in the neutral point voltage within multiple fault time intervals.

[0047] At T6 to T F1 During: To simulate the first controllable switch T on the first bridge arm 11 An open circuit fault occurs, and the first controllable switch T of the first bridge arm is stopped during T5 to T6. 11 The control signal S 11 The stopped signal is crossed out in Figure 5, and the faulty controllable switch is also crossed out in Figure 6. Following the correct sequence change, during the previous period T5 to T6, the sequence of the neutral point voltage is zero, low, high (i.e. N, -ve, +ve). The first controllable switch T 11 The corresponding capacitor C 11 is charged to the conversion voltage (greater than 0V), the second controllable switch T 12 The corresponding capacitor C 12 is discharged to 0V. When T6 reaches T F1 During this period, only the fourth controllable switch T 14 and the fifth controllable switch T 15 is turned on, and the first controllable switch T 11 The control signal S 11 is disabled to simulate the first controllable switch T 11 An open circuit fault occurs. In this process, the first controllable switch T 11 The corresponding capacitor C 11 Discharge, the second controllable switch T 12 The corresponding capacitor C 12 Charging, the current i passing through the first inductor Ls1 L1 The transmission must continue in the same negative direction, forcing the first controllable switch T 11 The corresponding diode D 11 During T6 to T F1 During this period, the sequence of the neutral point voltage changes to high, low and zero (i.e. +ve, -ve, N), which is consistent with the normal sequence conversion. L1 When it reaches zero, the time interval ends.

[0048] T F1 to T F2 Period: In T F1 to T F2 During this period, the second controllable switch T 12 The corresponding second capacitor C 12 is discharged to zero, forcing the second controllable switch T 12 The corresponding diode D 12Commutation. The sequence of the neutral point voltage changes from high, low, and zero (i.e., +ve, -ve, and N) to zero, low, and high (i.e., N, -ve, and +ve). A normal sequence change should be from high, low, and zero (i.e., +ve, -ve, and N) to high, zero, and low (i.e., +ve, N, and -ve). During this time interval, the sequence change of the neutral point voltage differs from the normal sequence change. The processing module 113 can use this anomaly to determine whether the three-phase dual active bridge converter has a fault. In addition, after determining that a fault has occurred, the processing module 113 can also determine the location of the fault based on the incorrect change direction of the sequence change, which will be explained in the analysis of the subsequent time interval.

[0049] T F2 to T F3 Period: In T F2 to T F3 During this period, the first controllable switch T 11 The corresponding capacitor C 11 , the second controllable switch T 11 The corresponding second capacitor C 12 The resonant circuit between the first inductor Ls1 and the first controllable switch T 11 The corresponding diode D 11 Reversing and second controllable switch T 12 The corresponding diode D 12 This will change the sequence of the neutral point voltage from zero low high (i.e. N, -ve, +ve) to high low zero (i.e. +ve, -ve, N). The change of the sequence of the neutral point voltage can be used as the basis for determining the fault location. When the fifth controllable switch is turned off and the sixth controllable switch is turned on according to the normal switching of the control signal, the T F2 to T F3 The time interval ends.

[0050] T F3 to T F4 Period: T F3 to T F4 At the beginning of the period, the sixth controllable switch is turned on, changing the sequence of the neutral point voltage from high, low, and zero (i.e., +ve, -ve, N) to high, zero, and low (i.e., +ve, N, -ve). This step of the sequence change of the neutral point voltage is the second and final step in determining the fault location. If the sequence change of the neutral point voltage is consistent with the sequence change in the previous time interval and the sequence change in this time interval, the fault location of the three-phase dual active bridge converter can be determined to be the first controllable switch T 11 .

[0051] FIG7 is a state diagram of a sequence change of the neutral point voltage from normal to faulty, provided by an embodiment of the present application. The diagram shows a complete state diagram of the normal sequence change and the fault sequence change when the first controllable switch fails. Referring to FIG7 , using simulation combined with circuit state analysis, three sequence changes of the neutral point voltage after the first controllable switch fails can be determined. The six-cycle sequence in the inner circle represents the normal sequence change of the neutral point voltage under normal working conditions of the three-phase dual-active bridge converter. In the case of an open circuit fault in the first controllable switch, there are three fault sequence changes of the neutral point voltage from the normal area to the fault judgment area, depending on the timing of the fault. These three sequence changes are different from the normal sequence changes and can be used to determine whether a fault exists. This judgment is the first stage of the fault judgment procedure.

[0052] The above simulation results and circuit analysis confirm that under normal operation of the three-phase dual-active bridge converter, the sequence of changes in the three neutral-point voltages follows a normal cycle. However, after an open-circuit fault is introduced into a controllable switch, the sequence of changes in the three neutral-point voltages no longer follows this predetermined normal cycle. Using this simulation method, faults are introduced sequentially into multiple controllable switches. The simulation results shown in the figure show that after an open-circuit fault is introduced into any controllable switch on the primary side, the sequence of changes in the three neutral-point voltages no longer follows the predetermined normal cycle. Based on this, the relative relationship between the sequence of changes in the neutral-point voltages and the normal cycle can be used to determine the occurrence of a fault in the three-phase dual-active bridge converter.

[0053] The present invention provides a fault diagnosis device for a three-phase dual-active bridge converter, comprising a signal acquisition module and a processing module. The acquisition circuit in the signal acquisition module is connected to the neutral points of each of the three bridge arms on the primary side of the three-phase dual-active bridge converter to collect the neutral point voltage between the neutral points of each pair of bridge arms on the primary side of the three-phase dual-active bridge converter. The processing module is connected to the signal acquisition module and configured to determine the occurrence of a fault in the three-phase dual-active bridge converter based on the relative relationship between the sequence of changes in the neutral point voltage and the normal sequence of changes. This facilitates fault diagnosis of the three-phase dual-active bridge converter. By using voltage to analyze the presence of a fault in the three-phase active bridge converter, no sensor elements are required in the converter. Data processing functions are integrated into the processing module of the original converter, reducing the complexity of the fault diagnosis circuit. Using voltage for diagnosis avoids the need to process large amounts of sensor data, thereby improving the speed of diagnosis.

[0054] Optionally, FIG8 is a schematic diagram of the components of another fault diagnosis device for a three-phase dual-active bridge converter provided in an embodiment of the present application. FIG9 is a circuit diagram of a group of preprocessing units and their corresponding analog-to-digital conversion circuits in a signal acquisition module provided in an embodiment of the present application. Based on the aforementioned embodiment, referring to FIG8 , the signal acquisition module 114 includes a preprocessing unit 801 and an analog-to-digital conversion unit 802. The preprocessing unit 801 is configured to obtain an analog signal of the neutral point voltage and preprocess the analog signal. The analog-to-digital conversion unit 802 is connected to the preprocessing unit 801 and the processing module 113, respectively. The analog-to-digital conversion unit 802 is configured to convert the preprocessed analog signal of the neutral point voltage into a digital signal of the neutral point voltage and transmit the digital signal of the neutral point voltage to the processing module.

[0055] The preprocessing unit 801 is a circuit component that collects and preprocesses the analog signal of the neutral point voltage. Depending on the user's desired preprocessing procedures, different functional circuits can be configured within the preprocessing unit 801. Exemplarily, preprocessing can include attenuation, filtering, isolation, and amplification. The analog-to-digital conversion unit 802 is a conversion circuit that converts the preprocessed analog signal of the neutral point voltage into a digital signal. Exemplarily, the digital signal can include a two-bit binary signal. The number of preprocessing units and analog-to-digital conversion units can both be three, with each preprocessing unit 801 corresponding to each analog-to-digital conversion unit 802. Each preprocessing unit 801 is connected to the neutral points of two bridge arms, and the bridge arm neutral points corresponding to multiple preprocessing units 801 are not all the same. Exemplarily, the first preprocessing unit is connected to the neutral point of the first bridge arm and the neutral point of the second bridge arm, the second preprocessing unit is connected to the neutral point of the second bridge arm and the neutral point of the third bridge arm, and the third preprocessing unit is connected to the neutral point of the third bridge arm and the neutral point of the first bridge arm.

[0056] For example, in conjunction with Figures 8 and 9, the preprocessing operation may include attenuation, filtering, isolation, and amplification. Correspondingly, the preprocessing unit 801 may include an attenuation circuit 901, a filtering circuit 902, an isolation circuit 903, and an amplifier circuit 904. The attenuation circuit 901 is connected to the neutral points of its corresponding two bridge arms, and is configured to introduce and attenuate the analog signal of the voltage between its corresponding neutral points (Figure 9 uses the voltage of the first and second bridge arms as an example). The filtering circuit 902 is connected to the output of the attenuation circuit 901. The filtering circuit 902 can reduce the amount of noise in the analog signal. The isolation circuit 903 is provided between the output of the filtering circuit 902 and the input of the amplifier circuit 904. The isolation circuit 903 can isolate the subsequent analog-to-digital conversion unit 802 from the previous circuit to prevent damage to the subsequent circuit caused by a sudden increase in current in the previous circuit. The amplifier circuit 904 can amplify the analog signal on the secondary side of the isolation circuit 903 to adapt it to the signal range that the subsequent analog-to-digital conversion unit 802 can process. The analog-to-digital conversion unit 802 is connected to the output terminal of the amplifier circuit 904 and converts the preprocessed analog signal into a two-bit binary signal. For example, if the two-bit binary signal output by the analog-to-digital conversion unit 802 is 11, it indicates that the neutral point voltage corresponding to the analog-to-digital conversion unit 802 is high; if the two-bit binary signal output by the analog-to-digital conversion unit 802 is 10, it indicates that the neutral point voltage corresponding to the analog-to-digital conversion unit 802 is zero; and if the two-bit binary signal output by the analog-to-digital conversion unit 802 is 00, it indicates that the neutral point voltage corresponding to the analog-to-digital conversion unit 802 is low.

[0057] Continuing with FIG8 and FIG9, the attenuation circuit 901 includes two first resistors R1, two second resistors R2 and a third resistor R3 with a variable resistance connected in series between the neutral points of the two bridge arms. The voltage divider effect of the series resistors makes the voltage V between the two output terminals of the attenuation circuit atten is smaller than the neutral point voltage between the neutral points of the two bridge arms, so that the attenuation circuit performs a certain degree of attenuation operation on the neutral point voltage, and the degree of attenuation is related to the effective resistance value of the third resistor R3 connected in series.

[0058] The filter circuit 902 includes a first amplifier OP1, a second amplifier OP2, a third amplifier OP3, a fourth resistor R4, two fifth resistors R5, and four sixth resistors R6. The first input of the first amplifier OP1 and the first input of the second amplifier OP2 are connected via the fourth resistor R4. The second input of the first amplifier OP1 and the second input of the second amplifier OP2 are respectively connected to two different outputs of the attenuation circuit 901. The output of the first amplifier OP1 is connected to the first input of the first amplifier OP1 via a fifth resistor R5, and the output of the second amplifier OP2 is connected to the first input of the second amplifier OP2 via another fifth resistor R5. The first input of the third amplifier OP3 is connected to the output of the first amplifier OP1 via a sixth resistor R6, and is further connected to the output of the third amplifier OP3 via another sixth resistor R6. The second input of the third amplifier OP3 is connected to the output of the second amplifier OP2 via another sixth resistor R6, and is further connected to the ground terminal GND via another sixth resistor R6. The output terminal of the third amplifier OP3 is connected to one end of the primary coil in the isolation circuit 903 via the seventh resistor R7, and the second input terminal of the third amplifier OP3 is also connected to the other end of the primary coil in the isolation circuit 903. The voltage value between the output terminal of the third amplifier OP3 and the ground terminal GND (that is, the two ends of the primary coil of the isolation circuit 903) is the voltage between the neutral points after filtering V diff The filtered voltage is based on the ground potential, which reduces the data noise of the neutral point voltage.

[0059] The isolation circuit 903 includes a primary coil and a secondary coil. The isolation circuit 903 can isolate the current between the primary and secondary sides, and the secondary coil transmits the isolated neutral point voltage signal backward. The discharge circuit 904 includes a fourth amplifier OP4, a reference resistor R f and reference capacitor C f The first input terminal of the fourth amplifier OP4 is connected to one end of the secondary side coil, the second input terminal of the fourth amplifier OP4 is connected to the other end of the secondary side coil, and the output terminal of the fourth amplifier OP4 is connected to one end of the reference resistor. The reference resistor R f The other end of the reference capacitor C f Ground, reference resistor R f The other end is also connected to the analog-to-digital conversion unit 802 as the output end of the amplifier circuit 904.

[0060] The analog-to-digital conversion unit 802 includes a first comparator OP5, a second comparator OP6, and two eighth resistors R8. The first input of the first comparator OP5 is connected to the output of the amplifier circuit 904 via one eighth resistor R8. The first input of the second comparator is connected to the output of the isolation circuit via another eighth resistor. The second input of the first comparator OP6 is connected to the first reference potential DAC Ref1, and the second input of the second comparator OP6 is connected to the second reference potential DAC Ref2. The output of the first comparator OP5 and the output of the second comparator OP6 serve as the two outputs of the analog-to-digital conversion unit 802, which can output a two-bit binary signal after conversion.

[0061] The processing module can be connected to the output terminals of the three analog-to-digital conversion units in the signal acquisition module, respectively, and receive six binary signals. If the binary signals output by the signal acquisition module for the voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1 are 11, 00, and 10, respectively, the processing module can determine that the current voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1 are high, low, and zero, respectively, and determine, based on the cached data, that the normal sequence change is a conversion from high, low, and zero to high, zero, and low. If the signal acquisition module subsequently outputs the next set of binary signals for the voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1, respectively, which are 11, 10, and 00, respectively, then the three-phase dual-active bridge converter 101 can be determined to be normal. Otherwise, the three-phase dual-active bridge converter can be determined to have a fault. After processing by the preprocessing module 113 and the analog-to-digital conversion unit 802, the amount of signal data for the neutral point voltage is greatly reduced. The processing module 113 can then compare the voltage sequence changes and perform fault diagnosis based on the processed binary signals, significantly reducing the amount of data processing.

[0062] In an embodiment of the present application, a fault diagnosis device for a three-phase dual-active bridge converter is provided. The signal acquisition module includes a preprocessing unit and an analog-to-digital conversion unit, each corresponding to the neutral point voltage. The preprocessing unit is configured to obtain and preprocess the analog signal of the corresponding neutral point voltage. The analog-to-digital conversion unit is connected to its corresponding preprocessing unit and processing module, respectively. The analog-to-digital conversion unit is configured to convert the preprocessed analog signal of the neutral point voltage into a digital signal and transmit the digital signal to the processing module. This achieves preprocessing and conversion of the neutral point voltage, facilitates data analysis by the subsequent processing module, and further improves the reliability of the fault diagnosis device for the three-phase dual-active bridge converter.

[0063] Optionally, continuing to refer to Figure 8, on the basis of the aforementioned embodiment, the processing module 113 is configured to determine the fault location of the three-phase dual-active bridge converter 101 based on the relative relationship between the sequence change of the neutral point voltage and the fault sequence change when it is determined that the three-phase dual-active bridge converter 101 has a fault, wherein the fault sequence change corresponds to the controllable switch that has a fault.

[0064] The fault sequence change condition refers to the preset change condition of the neutral point voltage after the three-phase dual-active bridge converter 101 fails. It can be obtained based on experimental or simulation data and can include a continuous single change or multiple changes. After determining that the three-phase dual-active bridge converter 101 fails, the processing module 113 can call the cached data related to the fault sequence change condition to determine the fault sequence change condition that matches the sequence change condition of the neutral point voltage. The controllable switch corresponding to the fault sequence change condition is the controllable switch that fails. For example, in combination with Figure 8 and Figure 7, if the sequence change condition of the neutral point voltage meets any of the three fault sequence change conditions in Figure 7, it can be determined that the first controllable switch T 11 A malfunction has occurred.

[0065] By using simulation combined with circuit state analysis, it is also possible to determine the sequence change of the neutral point voltage after a fault occurs in multiple controllable switches on the primary side. Figure 10 is another state diagram of the sequence change of the neutral point voltage from normal to faulty, provided by an embodiment of the present application. The figure shows a complete state diagram of the normal sequence change and the fault sequence change when multiple controllable switches on the primary side fail, and shows the transition of the neutral point voltage from a normal sequence change to a fault sequence change due to multiple different controllable switch failures. In combination with Figures 8 and 10, the processing module 113 can determine whether a fault has occurred in the three-phase dual-active bridge converter based on whether the sequence change of the neutral point voltage conforms to the normal sequence change. Once the sequence change of the neutral point voltage does not change according to the order of the cycle, the sequence change of the neutral point voltage enters the fault judgment area, and the processing module 113 can determine that a fault has occurred in the three-phase dual-active bridge converter. For example, if the sequence of the neutral point voltage in a normal cycle changes from zero, low, and high to high, and then to high, low, and zero, which conforms to the normal sequence change, then the processing module 113 can temporarily determine that the three-phase dual-active bridge converter has not failed. However, if the sequence of the neutral point voltage in a normal cycle changes from zero, low, and high to zero, and then to zero, zero, which does not conform to the normal sequence change, then the processing module 113 can determine that the three-phase dual-active bridge converter has failed.

[0066] After determining that a fault has occurred in the three-phase dual-active bridge converter, the processing module 113 can also determine the location of the fault based on the correspondence between the further sequence changes of the neutral point voltage and the fault sequence changes. FIG10 shows all the fault sequence changes of the three-phase dual-active bridge converter when outputting power in the forward direction. For example, if the sequence of the neutral point voltage changes from zero zero zero to high zero low and then to high low zero, then based on all the fault sequence changes of the three-phase dual-active bridge converter when outputting power in the forward direction, the processing module 113 can locate the fault location as the fifth controllable switch T 15 .

[0067] Continuing with Figure 10 , the neutral point voltage, as a fault diagnosis signal, has excellent fault detection and location characteristics and can be effectively used for fault diagnosis. The state diagram in Figure 10 illustrates all possible sequence variations of the primary-side neutral point voltage under normal and fault conditions. In processing module 113, both normal and fault sequence variations can be stored in memory as state data. Therefore, after knowing the current sequence variation of the neutral point voltage, processing module 113 can compare it with the normal sequence variation in the state data to determine whether a fault has occurred. A normal sequence variation only includes six variations that repeat in a specific order. Based on the memory data and the current sequence variation of the neutral point voltage, the processing module can determine the correct sequence variation that should occur next and all possible fault sequence variations. For example, the three neutral point voltages—arm 12 voltage, arm 23 voltage, and arm 31 voltage—can each be represented by a high voltage +ve, a low voltage -ve, or a zero voltage N. The sequence of the voltage between the neutral points is high, low and zero (i.e., +ve, -ve, N). According to the sequence change state diagram shown in Figure 11, the sequence of the voltage between the neutral points may have three possible changes. If the sequence of the voltage between the neutral points is converted to high, zero and low (i.e., +ve, N, -ve), the processing module can determine that the three-phase dual-active bridge converter is operating normally. However, if the sequence of the voltage between the neutral points is converted to zero, zero and zero (i.e., N, N, N) or zero, low and high (i.e., N, -ve, +ve), the processing module 113 can determine that the three-phase dual-active bridge converter has failed. Further, on the one hand, if the sequence of the voltage between the neutral points is converted from high, low and zero (i.e., +ve, -ve, N) to zero, zero and zero (i.e., N, N, N), the processing module 113 can directly determine that a result is that the fourth controllable switch T 14A fault occurs. The subsequent sequence of the neutral point voltage will further convert to zero high low (i.e., N, +ve, -ve), and then convert to high zero low (i.e., +ve, N, -ve). On the other hand, if the sequence of the neutral point voltage changes from high low zero (i.e., +ve, -ve, N) to zero low high (i.e., N, -ve, +ve), there may be two possible positioning results: First, if the sequence of the neutral point voltage changes from zero low high (i.e., N, -ve, +ve) to zero high low (i.e., N, +ve, -ve), then the processing module can determine that the second controllable switch T12 has a fault; Second, if the sequence of the neutral point voltage changes from zero low high (i.e., N, -ve, +ve) to high low zero (+ve, -ve, N), then the processing module can determine that the first controllable switch T11 has a fault, and the subsequent sequence of the neutral point voltage will further convert to high zero low (i.e., ve, N, -ve). By adopting such a comparison method, no matter which controllable switch on the primary side fails, the processing module 113 can quickly and accurately determine the fault location.

[0068] The fault judgment device of the three-phase dual-active bridge converter provided in the embodiment of the present application, the processing module is also used to determine the fault location of the three-phase dual-active bridge converter based on the relative relationship between the sequence change of the neutral point voltage and the fault sequence change when a fault occurs in the three-phase dual-active bridge converter, thereby achieving rapid fault location and reducing the difficulty of subsequent maintenance.

[0069] In order to verify the feasibility of the fault judgment and location mechanism in the fault judgment device of the three-phase dual-active bridge converter, a hardware prototype of the three-phase dual-active bridge converter and its fault judgment device was developed according to the design specifications given in Table 2.

[0070] Table 2 Parameter design table of the hardware prototype of the three-phase dual active bridge converter

[0071] In conjunction with Figure 9, the voltages of the first and second bridge arms, the voltages of the second and third bridge arms, and the voltages of the third and first bridge arms are extracted from the neutral points of the three bridge arms on the primary side and fed to the signal acquisition module. The main purpose of the circuit shown in Figure 9 is to attenuate, isolate, and convert the corresponding neutral point voltages (the figure shows the voltage of the first and second bridge arms V AB ) is converted into a binary digital signal to represent it. The neutral point voltage is a high-voltage analog signal that cannot be directly fed to the processing module and requires attenuation, isolation and analog-to-digital conversion. The attenuation circuit attenuates the high-voltage analog signal into a low-voltage analog signal. The filter circuit removes the noise in the low-voltage analog signal. Next, the isolation circuit can provide current isolation for the circuits on both sides, and feed the isolated signal to the amplification circuit, and then to the analog-to-digital conversion circuit. Finally, the analog-to-digital conversion circuit outputs a two-bit binary signal (the figure shows the voltage V ABTable 3 shows the voltages of the first and second bridge arms V AB The analog signal of the neutral-point voltage extracted from the three-phase dual-active bridge converter is converted into a two-bit binary signal. Thus, the three neutral-point voltages of the three-phase dual-active bridge converter are converted into six-bit binary signals, which the processing module uses for analysis and processing.

[0072] Table 3. Voltage of bridge arm 1 and 2 V AB Table of conversion schemes to binary signals

[0073] FIG11 is a waveform diagram of a control signal of a first controllable switch and a voltage between three neutral points during normal operation provided by an embodiment of the present application. This waveform is a normal waveform extracted from a hardware prototype of a three-phase dual-active bridge converter. The horizontal axis is time and the vertical axis is voltage value. In conjunction with FIG11 , the control signal S of the first controllable switch is 11 The waveform is shown at the top, and the three groups of neutral point voltages V are shown below from top to bottom. AB 、V BC and V CA . The voltage of the first and second bridge arms is V AB Lagging second and third bridge arm voltage V BC 120 degrees, V BC Hysteresis V CA 120 degrees. Normally, the neutral point voltage changes from high potential to zero potential, then to low potential, and repeats the cycle.

[0074] FIG12 is a waveform diagram of the control signal of the first controllable switch and the voltage between the three neutral points when the first controllable switch fails. In conjunction with FIG12 , the control signal S of the first controllable switch 11 The waveform is shown at the top, and the three groups of neutral point voltages V are shown below from top to bottom. AB 、V BC and V CA When the first controllable switch fails (ie stops supplying the control signal S 11 ) After that, the voltage V between the three neutral points can be detected AB 、V BC and V CA Two of them have abnormal changes, among which the fault is represented by the symbol OCF in the figure. The neutral point voltage V AB 、V BC and V CA The signal is fed to the signal acquisition module, which performs pre-processing such as attenuation and isolation on the neutral point voltage. The module then uses an analog-to-digital conversion circuit to convert the neutral point voltage into a binary signal. Each neutral point voltage is represented by two binary signals.

[0075] FIG13 is a waveform diagram of the control signal of the first controllable switch, the input signal and the output signal of the signal acquisition module when the first controllable switch fails. In conjunction with FIG13 , the top waveform is the control signal S of the first controllable switch. 11 The second and third waveforms are the waveforms of the first and second bridge arm voltages V AB The waveforms of the corresponding binary output signals CMP1H and CMP1L after processing. The bottom waveform is the voltage V of the first and second bridge arms collected by the signal acquisition module. AB The input signal, that is, the voltage of the first and second bridge arms V AB Under normal working conditions, the voltage of the first and second bridge arms V AB Normal, the binary signals CMP1H and CMP1L output by the signal acquisition module are also normal. However, when the first controllable switch T 11 When an open circuit fault occurs, the voltage of the first and second bridge arms V AB The corresponding binary signals CMP1H and CMP1L also have abnormalities. Similarly, the three neutral point voltages can be converted into 6-bit binary signals for output. Table 4 shows the three neutral point voltages V AB 、V BC and V CA And the binary output signals corresponding to the three respectively.

[0076] Table 4 Neutral point voltage V AB 、V BC 、V CA And the binary output signal table corresponding to the three

[0077] FIG14 is a waveform diagram of multiple signals of a three-phase dual-active bridge converter and a fault judgment device thereof provided in an embodiment of the present application, and FIG15 is an amplified waveform diagram of multiple signals of a three-phase dual-active bridge converter and a fault judgment device thereof provided in an embodiment of the present application, wherein each unit grid on the horizontal axis in FIG14 represents 100 μs, and each unit grid on the horizontal axis in FIG15 represents 5 μs. FIG15 is an amplified version of the waveform of FIG14 , which can more clearly show the performance of the fault judgment mechanism in terms of accuracy and detection speed. In combination with FIG14 and FIG15 , the control signal S of the first controllable switch 11 Stop to simulate the failure of the first controllable switch. AB and the Sany bridge arm voltage V CA The abnormality in the voltage of the first and second bridge arms V AB The corresponding binary signals CMP1H and CMP1L and the voltage of the three-way bridge arm V CADeviations occur in the corresponding binary signals CMP3H and CMP3L. Because the voltages VBC of the second and third bridge arms are not affected by the fault of the first controllable switch, the corresponding binary signals CMP2H and CMP2L of the voltages VBC of the second and third bridge arms are unaffected. These six binary signals CMP1H, CMP1L, CMP2H, CMP2L, CMP3H, and CMP3L are fed to the processing module for final judgment, and the judgment result is output in the form of a fault judgment signal FD and two-bit fault location signals FI bit0 and FI bit1. The fault judgment signal FD outputs a high level 1.8 μs after the fault occurs to indicate the presence of a fault. The fault location signals FI bit0 and FI bit1 indicate the fault location using two-bit binary signals. Multiple groups of fault location signals can be set as needed to indicate whether all controllable switches have faults. Table 5 is a table explaining the meaning of the two-bit fault location signals.

[0078] Table 5 Analysis of the meaning of fault location signals

[0079] Figure 15 also shows that the fault location time is 7.4 μs. The processing module can implement the determination, location, and indication of an open-circuit switch fault using an electronic processor. The electronic processor can be at least one of a microcontroller, a microprocessor, a field-programmable gate array (FPGA), a digital signal processor, a programmable gate array, a subject logic unit, a Boolean logic unit, an electronic logic circuit, a digital circuit, an application-specific integrated circuit, or any other data processing device. In one embodiment, the electronic processor can also execute software instructions stored in a data storage device.

[0080] An embodiment of the present application provides a fault diagnosis device for a three-phase dual-active bridge converter. The neutral point voltage is used as a fault diagnosis signal. Within a switching cycle, the deviation of the neutral point voltage from its normal sequence can effectively determine the presence of a fault. The fault diagnosis process is completed within 1.8 μs, which is less than 1 / 25 of the switching cycle. The fault switch is accurately located within 7.4 μs, less than 1 / 6 of the switching cycle. Therefore, the fault diagnosis device proposed in this application has an extremely fast detection speed, which is very important for early fault diagnosis in a three-phase dual-active bridge converter. It can protect the rest of the converter from the effects of long-term open-circuit faults, such as asymmetry in inductor current, neutral point voltage, and inductor voltage, which can cause current overshoot, capacitor voltage imbalance, and magnetic component saturation, affecting the reliability and safety of the three-phase dual-active bridge converter during long-term operation.

[0081] Furthermore, the present fault diagnosis device does not require additional sensors to detect fault characteristics, as the neutral-point voltage can be directly tapped from the neutral point of the primary side of the three-phase dual-active bridge converter and fed to the signal acquisition module for further data processing. This means that the fault diagnosis device for the three-phase dual-active bridge converter proposed in this application can be added to the three-phase dual-active bridge converter in the related art without any hardware modification. The processing module, combined with the low-cost operational amplifier circuit and resistor network in the signal acquisition module, can use a simple comparator circuit as an analog-to-digital conversion unit to convert the neutral-point voltage into a two-bit binary signal. Without the need for complex signal processing such as shifting, averaging, or conversion, the binary signal can accurately represent the neutral-point voltage in real time and can be used in the processing module for final fault diagnosis and fault location.

[0082] The present application also provides a method for diagnosing a fault in a three-phase dual-active bridge converter. This method can be implemented by any of the aforementioned three-phase dual-active bridge converter fault diagnosis devices. FIG16 is a flow chart illustrating a method for diagnosing a fault in a three-phase dual-active bridge converter provided herein. Referring to FIG16 , the method for diagnosing a fault in a three-phase dual-active bridge converter includes the following steps.

[0083] S1601. Obtain a neutral point voltage between neutral points of each two bridge arms on the primary side of a three-phase dual active bridge converter.

[0084] The primary side of a three-phase dual-active bridge converter is provided with three bridge arms, and the connection point between the two switch combinations on each bridge arm is the neutral point of that bridge arm. The primary side of the three-phase dual-active bridge converter is provided with three bridge arms, which can be defined as the first bridge arm, the second bridge arm, and the third bridge arm. The bridge arm combinations can be 1-2, 2-3, and 3-1, respectively. For example, corresponding to the bridge arm combinations, the neutral point voltage can include the 1-2 bridge arm voltage between the neutral point of the first bridge arm and the neutral point of the second bridge arm, the 2-3 bridge arm voltage between the neutral point of the second bridge arm and the neutral point of the third bridge arm, and the 3-1 bridge arm voltage between the neutral point of the second bridge arm and the neutral point of the third bridge arm.

[0085] S1602: Determine whether a fault occurs in the three-phase dual active bridge converter based on a relative relationship between a sequence change of the neutral point voltage and a normal sequence change.

[0086] The sequence of neutral point voltages refers to the sequential combination of the three neutral point voltages: the voltages of arm 1 and arm 2, the voltages of arm 2 and arm 3, and the voltages of arm 3 and arm 1. A normal sequence change refers to the correct sequence change of the neutral point voltages, which is related to the sequence of changes in the switching states of the primary-side controllable switches in the three-phase dual-active bridge converter. Whether the sequence change of the neutral point voltages conforms to the normal sequence change can be determined to determine whether the three-phase dual-active bridge converter has failed. For example, if, in a normal sequence change, the sequence combination of the three neutral point voltages: the voltages of arm 1 and arm 2, the voltages of arm 2 and arm 3, and the voltages of arm 3 and arm 1 is high-zero-low (i.e., the voltages of arm 1 and arm 2 are high, the voltages of arm 2 and arm 3 are zero, and the voltages of arm 3 and arm 1 are low), the next step should be to change to zero-high-low. However, in an actual sequence change, if the sequence combination of the voltages of arm 1 and arm 2, the voltages of arm 2 and arm 3, and the voltages of arm 3 and arm 1 changes from high-zero-low to low-high-zero, the processing module can determine that the three-phase dual-active bridge converter has failed.

[0087] For example, if in a normal sequence change situation, the sequence combination of the three neutral point voltages of the one-two bridge arm voltage, the two-three bridge arm voltage and the three-one bridge arm voltage is high zero low (that is, the one-two bridge arm voltage is a high potential, the two-three bridge arm voltage is a zero potential and the three-one bridge arm voltage is a low potential), the next step should be to change to zero high low. In an actual sequence change situation, if the sequence combination of the one-two bridge arm voltage, the two-three bridge arm voltage and the three-one bridge arm voltage changes from high zero low to low high zero, then the processing module can determine that the three-phase dual active bridge converter has a fault.

[0088] This embodiment provides a fault diagnosis method for a three-phase dual-active bridge converter. The method obtains the neutral point voltage between the neutral points of each two bridge arms on the primary side of the three-phase dual-active bridge converter. Based on the relative relationship between the sequence of changes in the neutral point voltage and the normal sequence of changes, the method determines whether the three-phase dual-active bridge converter has a fault. This method implements fault diagnosis for the three-phase dual-active bridge converter. By using voltage to analyze the presence of a fault in the three-phase active bridge converter, no sensor elements are required. Data processing functions are integrated into the original converter's processing module, reducing the complexity of the fault diagnosis circuit. Using voltage for diagnosis avoids the need to process large amounts of sensor data, thereby improving the speed of diagnosis.

[0089] FIG17 is a flow chart of another method for fault determination of a three-phase dual-active bridge converter provided in an embodiment of the present application. Based on the foregoing embodiment, referring to FIG17 , the method for fault determination of a three-phase dual-active bridge converter includes the following steps.

[0090] S1701. Obtain a neutral point voltage between neutral points of each two bridge arms on the primary side of a three-phase dual active bridge converter.

[0091] The neutral point voltage includes the voltage of the first and second bridge arms, the voltage of the second and third bridge arms, and the voltage of the third and first bridge arms.

[0092] S1702 , pre-process and perform analog-to-digital conversion on the acquired analog signals of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages, respectively, to generate digital signals of the first and second bridge arm voltages, the second and third bridge arm voltages, and the third and first bridge arm voltages.

[0093] Preprocessing includes attenuation processing, filtering processing, and isolation processing. The digital signal may include a two-bit binary signal. After attenuation processing, filtering processing, isolation processing, and analog-to-digital conversion processing, the analog signals of the 12-bridge arm voltage, the 23-bridge arm voltage, and the 31-bridge arm voltage can be converted into two-bit binary signals respectively. Three groups of two-bit binary signals, a total of six-bit binary signals. For example, the sequence of the neutral point voltage is zero, high, and low, which can be converted into a six-bit binary signal 10, 11, and 00 (or 101100), where 10 corresponds to zero potential, 11 corresponds to high potential, and 00 corresponds to low potential.

[0094] S1703: When the sequence of the neutral point voltage changes according to a normal sequence, determine that the three-phase dual active bridge converter operates normally.

[0095] A normal sequence of changes includes: the sequential combination of the voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1 transitioning from high-low-zero to high-zero-low, then from high-zero-low to zero-high-low, then from zero-high-low to low-high-zero, then from low-high-zero to low-zero-high, then from low-zero-high to zero-low-high, then back to high-low-zero and repeating the cycle. If the sequence of neutral point voltages changes according to the normal sequence, then it can be determined that the three-phase dual-active bridge converter is operating normally. For example, if the neutral point voltage changes from high-zero-low to zero-high-low according to the normal sequence, then it can be determined that the three-phase dual-active bridge converter is operating normally.

[0096] S1704: When the sequence of the neutral point voltage does not change according to the normal sequence, it is determined that a fault has occurred in the three-phase dual active bridge converter.

[0097] If the neutral point voltage sequence does not change according to the normal sequence, then it can be determined that the three-phase dual active bridge converter has failed. For example, if the neutral point voltage does not change according to the normal sequence after high-zero-low and then zero-high-low, but instead changes to low-high-zero, then it can be determined that the three-phase dual active bridge converter has failed.

[0098] S1705: Locate the controllable switch where the fault occurs based on the corresponding relationship between the subsequent sequence change of the neutral point voltage and the fault sequence change.

[0099] Subsequent sequence changes refer to the sequence changes in the neutral point voltage after a fault is detected in a three-phase dual-active bridge converter. In the event of a three-phase dual-active bridge converter fault, the subsequent sequence changes in the neutral point voltage are compared to determine which fault sequence change scenario corresponds to the faulty controllable switch. If the subsequent sequence changes match a set of fault sequence changes, the controllable switch corresponding to that set of fault sequence changes is the faulty controllable switch, thus completing fault location.

[0100] The fault diagnosis method for a three-phase dual-active bridge converter provided in an embodiment of the present application preprocesses and performs analog-to-digital conversion on the acquired analog signals of the voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1, respectively, to generate digital signals of the voltages of arm 1 and 2, arm 2 and 3, and arm 3 and 1. Based on the digital signals, the method determines that the three-phase dual-active bridge converter is operating normally if the sequence of the neutral point voltages changes according to a normal sequence. If the sequence of the neutral point voltages does not change according to a normal sequence, the method determines that the three-phase dual-active bridge converter has failed. Based on the correspondence between the subsequent sequence of changes in the neutral point voltages and the fault sequence, the faulty controllable switch is located, thereby achieving fault diagnosis and location for the three-phase dual-active bridge converter. In this process, the acquired analog voltages are converted into digital signals, facilitating data processing and analysis, reducing the storage pressure for data corresponding to normal and fault sequence changes, and reducing fault diagnosis costs while improving diagnosis speed and reliability.

[0101] The present application also provides an electronic device. Figure 18 shows a schematic diagram of the structure of an electronic device that can be used to implement an embodiment of the present application. The electronic device 1800 is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or required herein.

[0102] As shown in FIG18 , the electronic device 1800 includes at least one processor 11 and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12 and a random access memory (RAM) 13. The memory stores a computer program that can be executed by the at least one processor, and the processor 11 can perform a variety of appropriate actions and processes according to the computer program stored in the ROM 12 or the computer program loaded from the storage unit 18 into the RAM 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, ROM 12, and RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0103] Multiple components in the electronic device 10 are connected to the I / O interface 15, including an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0104] The processor 11 can be a variety of general-purpose and / or specialized processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors that run machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the fault determination method for a three-phase dual active bridge converter.

[0105] In some embodiments, the fault diagnosis method for a three-phase dual-active bridge converter can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the fault diagnosis method for a three-phase dual-active bridge converter described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the fault diagnosis method for a three-phase dual-active bridge converter in any other appropriate manner (e.g., via firmware).

[0106] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, FPGAs, application specific integrated circuits (ASICs), application specific standard parts (ASSPs), system on chips (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include implementation in one or more computer programs that are executable and / or interpreted on a programmable system comprising at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0107] Computer programs for implementing the methods of the present application may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0108] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. Examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, RAM, ROM, erasable programmable read-only memory (EPROM) or flash memory, optical fibers, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0109] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0110] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0111] A computing system may include a client and a server. The client and server are generally remote from each other and typically interact via a communication network. The client-server relationship arises through computer programs running on the respective computers and establishing a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, a host product within a cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and virtual private server (VPS) services.

[0112] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the multiple steps described in this application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of this application can be achieved. This is not limited herein.

Claims

1. A fault judgment device for a three-phase dual active bridge converter, comprising: A signal acquisition module, wherein the signal acquisition module is respectively connected to the neutral points of the three bridge arms on the primary side of the three-phase dual-active bridge converter, and the signal acquisition module is configured to collect the neutral point voltage between the neutral points of every two bridge arms on the primary side of the three-phase dual-active bridge converter; A processing module, the processing module is connected to the signal acquisition module, and the processing module is configured to determine whether the three-phase dual active bridge converter fails according to the relative relationship between the sequence change of the neutral point voltage and the normal sequence change.

2. The device according to claim 1, wherein: The signal acquisition module includes a preprocessing unit corresponding to the neutral point voltage one by one and an analog-to-digital conversion unit corresponding to the neutral point voltage one by one; The preprocessing unit is configured to obtain the analog signal of the corresponding neutral point voltage and preprocess the analog signal; The analog-to-digital conversion unit is connected to the corresponding preprocessing unit and the processing module respectively, and the analog-to-digital conversion unit is configured to convert the preprocessed analog signal of the neutral point voltage into a digital signal and send the digital signal to the processing module.

3. The device according to claim 1, wherein: The processing module is further configured to determine the fault location of the three-phase dual active bridge converter according to the relative relationship between the sequence change of the neutral point voltage and the fault sequence change when a fault occurs in the three-phase dual active bridge converter, wherein the fault sequence change corresponds to the controllable switch where the fault occurs.

4. A fault judgment method for a three-phase dual active bridge converter, comprising: Obtaining a neutral point voltage between neutral points of each two bridge arms on the primary side of the three-phase dual active bridge converter; Whether the three-phase dual active bridge converter fails is determined based on the relative relationship between the sequence change of the neutral point voltage and the normal sequence change.

5. The method according to claim 4, wherein: Determining whether the three-phase dual active bridge converter fails according to the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, including: When the sequence of the neutral point voltage does not change according to the normal sequence, Determining that the three-phase dual active bridge converter fails; In the case where the sequence of the neutral point voltage changes according to the normal sequence change condition, it is determined that the three-phase dual active bridge converter operates normally.

6. The method according to claim 4, wherein: The neutral point voltage includes a bridge arm voltage of one-two, a bridge arm voltage of two-three, and a bridge arm voltage of three-one; Before determining the fault occurrence of the three-phase dual active bridge converter according to the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, the method further includes: The obtained analog signals of the one-two bridge arm voltage, the analog signals of the two-three bridge arm voltage, and the analog signals of the three-one bridge arm voltage are respectively preprocessed and analog-to-digital converted to generate digital signals of the one-two bridge arm voltage, the digital signals of the two-three bridge arm voltage, and the digital signals of the three-one bridge arm voltage.

7. The method according to claim 6, wherein: The preprocessing includes attenuation processing, filtering processing and isolation processing.

8. The method according to claim 6, wherein: The normal sequence change includes: the sequential combination of the one-two bridge arm voltage, the two-three bridge arm voltage and the three-one bridge arm voltage changes from high-low-zero to high-zero-low, then from high-zero-low to zero-high-low, then from zero-high-low to low-high-zero, then from low-high-zero to low-zero-high, then from low-zero-high to zero-low-high, then from zero-low-high back to high-low-zero and cycle.

9. The method according to any one of claims 4 to 8, wherein: After determining the fault occurrence of the three-phase dual active bridge converter according to the relative relationship between the sequence change of the neutral point voltage and the normal sequence change, the method further includes: In the event of a fault in the three-phase dual active bridge converter, the faulty controllable switch is located according to the corresponding relationship between the subsequent sequence change of the neutral point voltage and the fault sequence change.

10. An electronic device comprising: at least one processing module; as well as A memory in communication with the at least one processing module; wherein, The memory stores a computer program executable by the at least one processing module, wherein the computer program is executed by the at least one processing module so that the at least one processing module can perform A fault judgment method for a three-phase dual active bridge converter as claimed in any one of claims 4 to 9.

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