Power converter and fault detection method thereof
By controlling the first bridge arm of the power converter to output pulse signals and blocking the driving signals of the same-direction switching elements in the second bridge arm, the filter capacitor voltage is used to identify short-circuit faults, and the problem of the failure of the switching element short-circuit faults in the prior art is solved, achieving efficient and reliable fault detection.
Patent Information
- Application Number
- CN202510020591.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-06
- Publication Date
- 2025-04-25
AI Technical Summary
The prior art cannot effectively identify short-circuit faults in switching elements in power converters, resulting in insufficiency of detection.
By controlling the output pulse signal of the first bridge arm and blocking the driving signal of the switching element in the same direction in the second bridge arm, a short circuit fault is determined by using the voltage across the filter capacitor.
It realizes accurate identification of short-circuit faults of switching components, and the detection method is simple, efficient and reliable.
Smart Images
Figure CN119891765A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics technology, and in particular to a power converter and a fault detection method thereof. Background Art
[0002] As a power conversion device, power converters can invert DC power into AC power and can also perform DC power conversion. During mass production or before startup, power converters need to be quality tested to ensure that they work properly, reliably and stably, to avoid faulty machines leaving the factory and causing serious consequences such as machine explosion. Testing individual components of power converters separately will result in a long testing cycle and affect mass production efficiency.
[0003] At present, the prior art generally determines whether the power converter has a fault by detecting the resonant frequency of the power converter, but this method cannot identify the short circuit fault of the switching element. Summary of the invention
[0004] Based on this, it is necessary to provide a power converter and a fault detection method thereof to address the above technical issues.
[0005] In a first aspect, an embodiment of the present invention provides a power converter, comprising at least one first bridge arm, a second bridge arm, a resonant circuit connected between the first bridge arm and the second bridge arm, a filter capacitor connected to an output end of the second bridge arm, and a control circuit connected to the first bridge arm and the second bridge arm; the second bridge arm comprises a plurality of switch elements;
[0006] The control circuit is used to control the first bridge arm to output a pulse signal and block the driving signal of the switch element with the same direction in the second bridge arm;
[0007] Based on the voltages at both ends of the filter capacitor, it is determined whether there is a short-circuit fault in the switch elements whose drive signals are blocked.
[0008] In some embodiments, if the absolute value of the voltage responded to at both ends of the filter capacitor does not reach a set threshold within a set time, it is determined that there is a short-circuit fault in the switch elements whose drive signals are blocked.
[0009] In some embodiments, the second bridge arm includes at least two groups of reversely connected switch elements;
[0010] The control circuit blocks the driving signal of the switch element with the same direction in the second bridge arm, and controls the switch element connected in the opposite direction to the switch element with the same direction to be always on.
[0011] In some embodiments, the second bridge arm includes at least two groups of switch elements connected in the same direction;
[0012] The control circuit blocks the driving signals of the at least two groups of switch elements connected in the same direction in the second bridge arm.
[0013] In some embodiments, the second bridge arm includes a first switch element, a second switch element, a third switch element, and a fourth switch element; the first switch element is reversely connected to the second switch element, and the third switch element is reversely connected to the fourth switch element;
[0014] The control circuit blocks the driving signals of the first switch element and the third switch element, and controls the second switch element and the fourth switch element to be normally on, and if the voltage responded by both ends of the filter capacitor does not reach the set positive threshold within a set time, it is determined that there is a short-circuit fault in the first switch element and the third switch element; or
[0015] The control circuit blocks the driving signals of the second switch element and the fourth switch element, and controls the first switch element and the third switch element to be always on. If the voltage responded to at both ends of the filter capacitor does not reach the set negative threshold within the set time, it is determined that there is a short-circuit fault in the second switch element and the fourth switch element.
[0016] In some embodiments, the second bridge arm includes a first half bridge arm and a second half bridge arm, the first half bridge arm includes a first switch element, a second switch element, a third switch element, and a fourth switch element; the first switch element is reversely connected to the second switch element, and the third switch element is reversely connected to the fourth switch element; the second half bridge arm includes a fifth switch element, a sixth switch element, a seventh switch element, and an eighth switch element; the fifth switch element is reversely connected to the sixth switch element, and the seventh switch element is reversely connected to the eighth switch element;
[0017] The control circuit blocks the driving signals of the first switch element, the third switch element, the fifth switch element, and the seventh switch element, and controls the second switch element, the fourth switch element, the sixth switch element, and the eighth switch element to be normally on. If the voltage responded to by both ends of the filter capacitor does not reach the set positive threshold within a set time, it is determined that there is a short-circuit fault in the first switch element, the third switch element, the fifth switch element, and the seventh switch element; or
[0018] The control circuit blocks the driving signals of the second switch element, the fourth switch element, the sixth switch element, and the eighth switch element, and controls the first switch element, the third switch element, the fifth switch element, and the seventh switch element to be normally on. If the voltage responded to by the two ends of the filter capacitor does not reach the set negative threshold within the set time, it is determined that there is a switch element with a short circuit fault among the second switch element, the fourth switch element, the sixth switch element, and the eighth switch element.
[0019] In some embodiments, it also includes: a transformer connected between the corresponding first bridge arm and the second bridge arm.
[0020] In some embodiments, the power converter is a DC-AC converter or a DC-DC converter.
[0021] In a second aspect, an embodiment of the present invention provides a fault detection method for a power converter, wherein the power converter includes at least one first bridge arm, a second bridge arm, a resonant circuit connected between the corresponding first bridge arm and the second bridge arm, a filter capacitor connected to an output end of the second bridge arm, and a control circuit connected to the first bridge arm and the second bridge arm, wherein the second bridge arm includes a plurality of switch elements, and the method includes:
[0022] Controlling the first bridge arm to output a pulse signal to block the driving signal of the switch element in the same direction in the second bridge arm;
[0023] Based on the voltages responded to at both ends of the filter capacitor, it is determined whether there is a short-circuit fault switch element among the switch elements whose drive signals are blocked.
[0024] In some embodiments, if the absolute value of the voltage responded to at both ends of the filter capacitor does not reach a set threshold within a set time, it is determined that there is a short-circuit fault in the switch elements whose drive signals are blocked.
[0025] The present application controls the first bridge arm to output a pulse signal and blocks the driving signal of the switch element in the same direction in the second bridge arm, and determines whether there is a switch element with a short-circuit fault among the switch elements whose driving signals are blocked based on the voltages responded to at both ends of the filter capacitor. The present application can accurately identify the short-circuit fault of the switch element, and the detection method is simple, efficient and reliable. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 A schematic diagram of the structure of a power converter in an embodiment provided in the present application;
[0027] Figure 2 A circuit diagram of a DC-AC converter in a first exemplary embodiment provided in the present application;
[0028] Figure 3 This is a schematic diagram of an equivalent circuit of a DC-AC converter when the switch elements Q3 and Q5 are not short-circuited in the first exemplary embodiment provided by the present application;
[0029] Figure 4 A waveform diagram of the first exemplary embodiment provided by the present application when the switch elements Q3 and Q5 are not short-circuited;
[0030] Figure 5 This is a schematic diagram of an equivalent circuit of a DC-AC converter when a switching element Q3 is short-circuited in the first exemplary embodiment provided by the present application;
[0031] Figure 6 This is a schematic diagram of an equivalent circuit of a DC-AC converter when a switching element Q5 is short-circuited in the first exemplary embodiment provided by the present application;
[0032] Figure 7 This is a schematic diagram of an equivalent circuit of a DC-AC converter when the switch elements Q3 and Q5 are short-circuited in the first exemplary embodiment provided by the present application;
[0033] Figure 8 A circuit diagram of a DC-AC converter in a second exemplary embodiment provided in the present application;
[0034] Fig. 9 A circuit diagram of a DC-AC converter in a third exemplary embodiment provided in the present application;
[0035] Fig.10 A circuit structure diagram of a dual active bridge DC-DC converter in a fourth exemplary embodiment provided in the present application;
[0036] Fig.11 A schematic flow chart of a method for detecting a fault in a power converter in an embodiment of the present application. DETAILED DESCRIPTION
[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the contents disclosed in the present application, some changes such as design, manufacturing or production based on the technical contents disclosed in the present application are only conventional technical means, and should not be understood as insufficient contents disclosed in the present application.
[0038] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.
[0039] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to greater than or equal to two. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The terms "first", "second", "third" and the like involved in the present application are merely used to distinguish similar objects and do not represent a specific ordering of the objects.
[0040] Figure 1A schematic diagram of the structure of a power converter in one embodiment provided in the present application, wherein the power converter includes at least one first bridge arm 101, a second bridge arm 102, a transformer 103 connected between the corresponding first bridge arm 101 and the second bridge arm 102, a resonant circuit 104 connected to the transformer 103, a filter capacitor Cf connected to the output end of the second bridge arm 102, and a control circuit (not shown in the figure) connected to the first bridge arm 101 and the second bridge arm 102.
[0041] The voltage across the filter capacitor Cf is V Cf .
[0042] The resonant circuit 104 can be connected between the transformer 103 and the first bridge arm 101, or between the transformer 103 and the second bridge arm 102, to achieve soft switching of the switching elements in the first bridge arm 101 and the second bridge arm 103. The resonant circuit 104 can be a single inductor, or a circuit form such as LC, CLLC, etc.
[0043] In some embodiments, the primary side of the transformer 103 is connected to the first bridge arm 101, and the secondary side is connected to the second bridge arm 102, for inputting the voltage V in In some embodiments, there may be multiple transformers 103, and the primary winding of each transformer 103 is connected to a first bridge arm 101, and the secondary winding is connected to the same second bridge arm 102. In some embodiments, the transformer 103 may be omitted.
[0044] The control circuit is used to control the first bridge arm 101 and the second bridge arm 102 to achieve power conversion.
[0045] The first bridge arm 101 may be a full bridge or a half bridge, and is used to invert direct current into alternating current.
[0046] In some embodiments, the power converter is, for example, a DC-AC converter, and the second bridge arm 102 includes multiple groups of switch elements for AC-AC conversion, wherein each group of switch elements includes at least two switch elements connected in reverse series, and the output end of the second bridge arm 102 provides an AC output, for example, to a power grid.
[0047] The second bridge arm 102 is, for example, a full-bridge cyclotron bridge arm or a half-bridge cyclotron bridge arm.
[0048] The second bridge arm 102 is, for example, a single-phase cyclotron bridge arm or a three-phase cyclotron bridge arm.
[0049] In some other embodiments, the power converter is, for example, a DC-DC converter, and in this case, the second bridge arm 102 may be a full-bridge rectifier circuit.
[0050] According to an embodiment of the present application, a power converter is provided. In some embodiments, as Figure 1 As shown, the control circuit controls the first bridge arm 101 to output a pulse signal and blocks the driving signal of the switch element in the same direction in the second bridge arm 102; based on the voltage V at both ends of the filter capacitor Cf Cf , determine whether there is a short-circuit fault switching element among the switching elements whose drive signals are blocked.
[0051] The pulse signal is, for example, a high-frequency narrow pulse voltage.
[0052] If the absolute value of the voltage V Cf If the set threshold value is not reached within the set time, it is determined that a switch element with a short circuit fault exists among the switch elements whose drive signals are blocked.
[0053] It should be noted that the above-mentioned "switching elements of the same direction" refers to the switching elements whose body diodes in the second bridge arm are cut off or turned on in the same direction relative to the bridge arm output voltage of the second bridge arm. Here, the bridge arm output voltage of the second bridge arm is equal to the voltage V across the filter capacitor. Cf .
[0054] In this embodiment, by controlling a first bridge arm to output a pulse signal and blocking the driving signal of the switch element in the same direction in the second bridge arm, based on the voltage V at both ends of the filter capacitor Cf , determine whether there is a short-circuit fault in the switch elements whose drive signals are blocked, so as to accurately identify the short-circuit fault of the switch element, and the control is simple, reliable and the detection efficiency is high.
[0055] Taking the power converter as a DC-AC converter as an example, Figure 2 Schematic diagram of the circuit of the DC-AC converter in the first exemplary embodiment of the present application. The DC input voltage of the DC-AC converter is V inThe first bridge arm 101 adopts an H-bridge structure (full-bridge circuit), and the input end of the first bridge arm 101 is connected in parallel with a capacitor Cin. The first bridge arm 101 includes a switch element Q1H, a switch element Q1L, a switch element Q2H, and a switch element Q2L. Specifically, the switch element Q1H and the switch element Q1L are connected in series at the input end of the first bridge arm 101 to form a half-bridge bridge arm, and the switch element Q2H and the switch element Q2L are connected in series at the input end to form the other half-bridge bridge arm. The second bridge arm 102 is a half-bridge type cycloconversion bridge arm, including two groups of switch elements, each group of switch elements includes at least two switch elements connected in series in reverse order. Specifically, the two groups of switch elements are connected in series between the two output terminals of the second bridge arm 102 to form a half-bridge bridge arm. The first group of switch elements of the second bridge arm 102 includes switch elements Q3 and switch elements Q4 connected in reverse order to form an upper bridge arm of the second bridge arm 102, and the second group of switch elements includes switch elements Q5 and switch elements Q6 connected in reverse order to form the second bridge arm 10 2, the connection point of the two groups of switch elements is the bridge arm midpoint, the output end of the second bridge arm 102 is connected to the filter circuit 105 composed of the filter capacitor Cf and the inductor Lf, the first output terminal of the second bridge arm 102 is connected to the inductor Lf, and the second output terminal of the second bridge arm 102 is connected to one end of the secondary winding of the transformer 103, and the other end of the secondary winding of the transformer 103 is connected to the bridge arm midpoint of the second bridge arm 102 through the resonant circuit 104, and the resonant circuit 104 includes the inductor Lr and the capacitor Cr connected in series. The turns ratio of the primary and secondary windings of the transformer 103 is 1:n.
[0056] In the first exemplary embodiment, the body diodes of the switch element Q3 and the switch element Q5 have the same cut-off direction, and are a group of switch elements in the same direction. When fault detection is performed on the switch element Q3 and the switch element Q5, the control circuit controls the first bridge arm 101 to output a pulse signal v x (For example, a high-frequency narrow pulse voltage), while blocking the driving signals of the switch elements Q3 and Q5, and controlling the switch elements Q6 and Q4 to be normally on. Then, based on the voltage V Cf It is determined whether there is a short-circuit faulty switching element among the switching elements Q3 and Q5.
[0057] The working principle of the embodiment of the present application will be described below with reference to the accompanying drawings. Specifically, Figure 3 is a schematic diagram of an equivalent circuit when neither the switch elements Q3 nor Q5 has a short circuit fault. Figure 3 As shown, nv x The pulse signal v provided by the first bridge arm 101 x The pulse signal after the secondary side is converted. In this application, the pulse signal v x 、nv x Taking high frequency narrow pulse voltage as an example, i rsis the resonant current flowing through the resonant circuit 104. When the switch elements Q3 and Q5 are not short-circuited, since the switch elements Q3 and Q5 are in the diode rectification state, the resonant cavity current i rs In the positive half cycle, when the body diode of the switching element Q3 is turned on, the body diode of the switching element Q5 is turned off. At this time, the high-frequency narrow pulse voltage nv x Through the resonant tank circuit formed by inductor Lr, capacitor Cr, and filter capacitor Cf, the resonant cavity current i rs The filter capacitor Cf is charged through the body diode of the switching element Q3; rs In the negative half cycle, when the body diode of the switching element Q5 is turned on, the body diode of the switching element Q3 is turned off. At this time, the high-frequency narrow pulse voltage nv x Through the resonant tank circuit formed by inductor Lr and capacitor Cr, the resonant cavity current i rs Through the body diode of the switching element Q5, the voltage V Cf It gradually increases and eventually reaches the set positive threshold V within the preset time. th+ , such as Figure 4 shown.
[0058] When the switch element Q3 fails in a short circuit, Figure 5 As shown, due to the reverse cutoff effect of the body diode of the switching element Q5, the high-frequency narrow pulse voltage nv x The resonant tank circuit is formed by the inductor Lr, the capacitor Cr and the filter capacitor Cf. rs In the positive half cycle, the resonant cavity current i rs The filter capacitor Cf is charged, and the resonant cavity current i rs In the negative half cycle, the filter capacitor Cf is discharged, so the voltage V Cf Approximately zero.
[0059] When the switch element Q5 fails to short circuit, Figure 6 , Figure 7 As shown, the body diode of the switching element Q3 and the filter capacitor Cf are short-circuited by the switching element Q5, and the high-frequency narrow pulse voltage nv x The resonant tank circuit is formed by the inductor Lr and the capacitor Cr. rs Positive half cycle and negative half cycle, the resonant cavity current i rs All pass through the switch element Q5 without affecting the voltage across the filter capacitor Cf, so the voltage V Cf Approximately zero.
[0060] According to the above analysis, it can be seen that by controlling the first bridge arm 101 to output a high-frequency pulse signal v xAt the same time, the driving signal of the switch element in the same direction in the second bridge arm 102 is blocked, and the switch element reversely connected to the switch element in the same direction is controlled to be normally turned on, and the voltage V Cf The detection method for determining whether a switch element whose driving signal is blocked has a short-circuit fault is relatively simple, efficient and reliable.
[0061] Based on the same fault detection principle, when fault detection is performed on the same-direction switch element Q4 and the switch element Q6, the control circuit can control the first bridge arm 101 to output a pulse signal, block the drive signals of the switch element Q4 and the switch element Q6, and control the switch element Q3 and the switch element Q5 to be always on. After that, the voltage V at both ends of the filter capacitor Cf can be collected. Cf , determine whether there is a short-circuit fault in the switching element Q4 and the switching element Q6.
[0062] It should be noted that, since the directions of the switch elements Q4 and Q6 are opposite to those of the switch elements Q3 and Q5, when the switch elements Q4 and Q6 are not faulty, the resonant cavity current i rs Reverse charge the filter capacitor Cf, that is, the voltage V Cf If the voltage V Cf The negative threshold V is not reached within the preset time. th- , it is considered that a short circuit fault occurs, otherwise, it is considered that no short circuit fault occurs.
[0063] Positive threshold V th+ With negative threshold V th- The absolute values of can be equal or unequal.
[0064] In some other embodiments, according to the output voltage V out and the voltage across the filter capacitor V Cf The correlation between the two can be used to collect the output voltage V of the power converter. out , according to the output voltage V of the power converter out It is determined whether there is a short-circuit fault in the blocked switching elements.
[0065] Figure 8This is a circuit diagram of a DC-AC converter in the second exemplary embodiment of the present application. The difference from the first exemplary embodiment is that the second bridge arm 102 is a full-bridge type cycloconversion bridge arm, including a first half bridge arm and a second half bridge arm, the first half bridge arm and the second half bridge arm respectively include two groups of switch elements, each group of switch elements includes at least two switch elements connected in reverse series, specifically, the first half bridge arm includes switch element Q31, switch element Q41, switch element Q51, switch element Q61; switch element Q31 and switch element Q41 are reversely connected, and switch element Q51 and switch element Q61 are reversely connected; the second half bridge arm includes switch element Q32, switch element Q42, switch element Q52, switch element Q62; the switch element Q32 and switch element Q42 are reversely connected, and the switch element Q52 and switch element Q62 are reversely connected. One end of the secondary winding of the transformer 103 is connected to the midpoint of the switching element Q41 and the switching element Q51 through the resonance circuit 104 , and the other end of the secondary winding of the transformer 103 is connected to the midpoint of the switching element Q42 and the switching element Q52 .
[0066] In the second exemplary embodiment, the switch elements Q31, Q32, Q51, Q52 are a group of switch elements with the same direction. When the switch elements Q31, Q32, Q51, Q52 are fault-detected, the control circuit controls the first bridge arm 101 to output a pulse signal, blocks the drive signals of the switch elements Q31, Q32, Q51, Q52, and controls the switch elements Q41, Q42, Q61, Q62 to be always on. Afterwards, the voltage V at both ends of the filter capacitor Cf can be collected. Cf , according to the voltage V at both ends of the filter capacitor Cf Cf Determine whether there is a short-circuit fault in the switch elements Q31, Q32, Q51, and Q52. Cf The positive threshold V is not reached within the preset time. th+ , it is considered that a short circuit fault occurs, otherwise, it is considered that no short circuit fault occurs.
[0067] The switch elements Q41, Q42, Q61, Q62 are another group of switch elements with the same direction. When the switch elements Q41, Q42, Q61, Q62 are fault-detected, the control circuit controls the first bridge arm 101 to output a pulse signal, blocks the drive signals of the switch elements Q41, Q42, Q61, Q62, and controls the switch elements Q31, Q32, Q51, Q52 to be normally on. Afterwards, the voltage V at both ends of the filter capacitor Cf is collected. Cf , according to the voltage V at both ends of the filter capacitor Cf Cf Determine whether there is a short-circuit fault in the switch elements Q41, Q42, Q61, and Q62. CfThe negative threshold V is not reached within the preset time. th- , it is considered that a short circuit fault occurs, otherwise, it is considered that no short circuit fault occurs.
[0068] The fault detection logic in the second exemplary embodiment is the same as that in the first exemplary embodiment and will not be described in detail herein.
[0069] Fig. 9 This is a circuit diagram of a DC-AC converter in the third exemplary embodiment of the present application. The difference from the first exemplary embodiment is that the second bridge arm 102 is a three-phase cycloconversion bridge arm, providing a three-phase AC output. The three-phase cycloconversion bridge arm is composed of switch element Q3a, switch element Q3b, switch element Q3c, switch element Q4a, switch element Q4b, switch element Q4c, switch element Q5a, switch element Q5b, switch element Q5c, switch element Q6a, switch element Q6b, and switch element Q6c. Among them, switch element Q3a, switch element Q3c, switch element Q4b, switch element Q5b, switch element Q6a, and switch element Q6c are a group of switch elements in the same direction; switch element Q3b, switch element Q4a, switch element Q4c, switch element Q5a, switch element Q6c, and switch element Q6b are another group of switch elements in the same direction.
[0070] In one possible implementation, when fault detection is performed on the switch elements Q4a, Q5a of phase a, the switch elements Q3b, Q6b of phase b, and the switch elements Q4c, Q5c of phase c, the control circuit controls the first bridge arm 101 to output a pulse signal, and simultaneously blocks the switch elements Q4a, Q5a of phase a, the switch elements Q3b, Q6b of phase b, and the switch elements Q4c, Q5c of phase c, and turns on the switch elements Q3a, Q6a of phase a, the switch elements Q4b, Q5b of phase b, and the switch elements Q3c, Q6c of phase c, and then collects the voltages responded at both ends of the filter capacitors Ca, Cb, and Cc, and determines whether there are switch elements with short-circuit faults among the blocked switch elements based on the voltages responded at both ends of the filter capacitors Ca, Cb, and Cc. That is, if the voltage difference between the filter capacitors Ca and Cb and the voltage difference between the filter capacitors Cc and Cb both reach the corresponding threshold values within the preset time, it is considered that no short circuit fault occurs; otherwise, it is considered that a short circuit fault occurs.
[0071] When fault detection is performed on the switch elements Q3a, Q6a of phase a, the switch elements Q4b, Q5b of phase b, and the switch elements Q3c, Q6c of phase c, the switch elements Q3a, Q6a of phase a, the switch elements Q4b, Q5b of phase b, and the switch elements Q3c, Q6c of phase c are blocked, the switch elements Q4a, Q5a of phase a, the switch elements Q3b, Q6b of phase b, and the switch elements Q4c, Q5c of phase c are turned on, the voltages at both ends of the filter capacitors Ca, Cb, and Cc are collected, and it is determined whether there is a switch element with a short-circuit fault among the blocked switch elements according to the voltages at both ends of the filter capacitors Ca, Cb, and Cc. That is, if the voltage difference between the two ends of the filter capacitors Cb and Ca and the voltage difference between the two ends of the filter capacitors Cb and Cc reach the corresponding threshold value within the preset time, it is considered that no short-circuit fault occurs, otherwise, it is considered that a short-circuit fault occurs.
[0072] In some other embodiments, the power converter has multiple transformers 103, the primary winding of each transformer 103 is connected to a first bridge arm 101, and the secondary winding is connected to the same second bridge arm 102. At this time, the control circuit controls one of the first bridge arms 101 to output a pulse signal.
[0073] Fig.10 This is a circuit diagram of a dual active bridge DC-DC converter in the fourth example embodiment of the present application. The difference from the first example embodiment is that the power converter is a DC-DC converter, which performs DC conversion and provides DC output. Specifically, the second bridge arm 102 is an H-bridge circuit, including switch elements Q7 and Q9 connected in the same direction and switch elements Q8 and Q10 connected in the same direction. One end of the secondary winding of the transformer 103 is connected to the midpoint of the switch element Q7 and the switch element Q9 through the resonant circuit 104, and the other end of the secondary winding of the transformer 103 is connected to the midpoint of the switch element Q8 and the switch element Q10. The conduction or cutoff direction of the body diodes of the switch elements Q7, Q9 and the switch elements Q8 and Q10 is consistent with the bridge arm output voltage of the second bridge arm 102, and the four are a group of switch elements in the same direction.
[0074] In the fourth exemplary embodiment, when fault detection is performed on the switch elements Q7, Q8, Q9, and Q10, the control circuit controls the first bridge arm 101 to output a pulse signal and blocks the drive signals of the switch elements Q7, Q8, Q9, and Q10. Then, the voltage V at both ends of the filter capacitor Cf is collected. Cf , according to the voltage V at both ends of the filter capacitor Cf Cf Determine whether there is a short-circuit fault in the switching elements Q7, Q8, Q9, and Q10. Cf The positive threshold V is not reached within the preset time.th+ , it is considered that a short circuit fault occurs, otherwise, it is considered that no short circuit fault occurs.
[0075] The fault detection logic in the fourth exemplary embodiment is the same as that in the first exemplary embodiment and will not be described in detail herein.
[0076] Based on the above power converter, the present application proposes a fault detection method for the power converter, such as Fig.11 As shown, the method includes:
[0077] S102: controlling a first bridge arm to output a pulse signal to block a driving signal of a switch element in the same direction in the second bridge arm;
[0078] S104: Determine whether there is a short-circuit fault switch element among the switch elements whose drive signals are blocked, based on the voltages responded to by both ends of the filter capacitor.
[0079] In some embodiments, the second bridge arm includes at least two groups of reversely connected switch elements, the control circuit blocks the driving signals of the switch elements in the same direction in the second bridge arm, and controls the switch elements reversely connected to the switch elements in the same direction to be always on.
[0080] In some embodiments, the second bridge arm includes at least two groups of switch elements connected in the same direction; and the control circuit blocks the driving signals of the at least two groups of switch elements connected in the same direction in the second bridge arm.
[0081] In some embodiments, if the absolute value of the voltage responded to at both ends of the filter capacitor does not reach a set threshold within a set time, it is determined that there is a short-circuit fault in the switch elements whose drive signals are blocked.
[0082] Since the fault detection method of this embodiment corresponds to the embodiments, principles and examples of the aforementioned power converter, for details not fully described in this embodiment, reference can be made to the relevant descriptions in the aforementioned embodiments and will not be repeated here.
[0083] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0084] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.
Claims
1. A power converter, characterized in that: The device comprises at least one first bridge arm, a second bridge arm, a resonant circuit connected between the first bridge arm and the second bridge arm, a filter capacitor connected to an output end of the second bridge arm, and a control circuit connected to the first bridge arm and the second bridge arm; the second bridge arm comprises a plurality of switch elements; The control circuit is used to control the first bridge arm to output a pulse signal and block the driving signal of the switch element with the same direction in the second bridge arm; Based on the voltages at both ends of the filter capacitor, it is determined whether there is a short-circuit fault in the switch elements whose drive signals are blocked.
2. The power converter according to claim 1, characterized in that: If the absolute value of the voltage responded to at both ends of the filter capacitor does not reach the set threshold within the set time, it is determined that there is a switch element with a short circuit fault in the switch elements whose drive signals are blocked.
3. The power converter according to claim 1 or 2, characterized in that: The second bridge arm comprises at least two groups of reversely connected switch elements; The control circuit blocks the driving signal of the switch element with the same direction in the second bridge arm, and controls the switch element connected in the opposite direction to the switch element with the same direction to be always on.
4. The power converter according to claim 1 or 2, characterized in that: The second bridge arm comprises at least two groups of switch elements connected in the same direction; The control circuit blocks the driving signals of the at least two groups of switch elements connected in the same direction in the second bridge arm.
5. The power converter according to claim 3, characterized in that: The second bridge arm includes a first switch element, a second switch element, a third switch element, and a fourth switch element; the first switch element is reversely connected to the second switch element, and the third switch element is reversely connected to the fourth switch element; The control circuit blocks the driving signals of the first switch element and the third switch element, and controls the second switch element and the fourth switch element to be normally on. If the voltage responded by both ends of the filter capacitor does not reach the set positive threshold within a set time, it is determined that there is a short-circuit fault in the first switch element and the third switch element. or The control circuit blocks the driving signals of the second switch element and the fourth switch element, and controls the first switch element and the third switch element to be always on. If the voltage responded to at both ends of the filter capacitor does not reach the set negative threshold within the set time, it is determined that there is a short-circuit fault in the second switch element and the fourth switch element.
6. The power converter according to claim 3, characterized in that: The second bridge arm includes a first half bridge arm and a second half bridge arm, the first half bridge arm includes a first switch element, a second switch element, a third switch element, and a fourth switch element; the first switch element is reversely connected to the second switch element, and the third switch element is reversely connected to the fourth switch element; The second half bridge arm includes a fifth switch element, a sixth switch element, a seventh switch element, and an eighth switch element; the fifth switch element is reversely connected to the sixth switch element, and the seventh switch element is reversely connected to the eighth switch element; The control circuit blocks the driving signals of the first switch element, the third switch element, the fifth switch element and the seventh switch element, and controls the second switch element, the fourth switch element, the sixth switch element and the eighth switch element to be normally on; if the voltage responded to by both ends of the filter capacitor does not reach the set positive threshold within a set time, it is determined that there is a switch element with a short circuit fault among the first switch element, the third switch element, the fifth switch element and the seventh switch element; or The control circuit blocks the driving signals of the second switch element, the fourth switch element, the sixth switch element, and the eighth switch element, and controls the first switch element, the third switch element, the fifth switch element, and the seventh switch element to be normally on. If the voltage responded to by the two ends of the filter capacitor does not reach the set negative threshold within the set time, it is determined that there is a switch element with a short circuit fault among the second switch element, the fourth switch element, the sixth switch element, and the eighth switch element.
7. The power converter according to claim 1, characterized in that: Also includes: A transformer connected between the corresponding first bridge arm and the second bridge arm.
8. The power converter according to claim 1, characterized in that: The power converter is a DC-AC converter or a DC-DC converter.
9. A fault detection method for a power converter, the power converter comprising at least one first bridge arm, a second bridge arm, a resonant circuit connected between the first bridge arm and the second bridge arm, a filter capacitor connected to an output end of the second bridge arm, and a control circuit connected to the first bridge arm and the second bridge arm, the second bridge arm comprising a plurality of switch elements, characterized in that: The method comprises: Controlling the first bridge arm to output a pulse signal, and blocking the driving signal of the switch element with the same direction in the second bridge arm; Based on the voltages at both ends of the filter capacitor, it is determined whether there is a short-circuit fault in the switch elements whose drive signals are blocked.
10. The method according to claim 9, characterized in that If the absolute value of the voltage responded to at both ends of the filter capacitor does not reach the set threshold within the set time, it is determined that there is a switch element with a short circuit fault in the switch elements whose drive signals are blocked.