Fault operation control system for power unit of high voltage frequency converter and high voltage frequency converter

Abstract

The utility model relates to a fault operation control system and high voltage frequency changer for power unit of high voltage frequency changer. The system includes: voltage sampling circuit, voltage of sampling direct current bus and output voltage fault indication signal when voltage is abnormal, fault trigger circuit, its input end is connected to each drive unit's output and voltage sampling circuit's output, fault type judgment circuit, its input end is connected to each drive unit's output and fault trigger circuit's output, fault counting circuit, its input end is connected to each drive unit's output and fault type judgment circuit's output, threshold comparison circuit, connects to the output of fault counting circuit and receives the count threshold value, shutdown control circuit, its input end is connected to threshold comparison circuit's output, and the response to the comparator indicates that the count value is greater than or equal to the count threshold value, to all drive unit output disconnect command, to provide the fault operation control system that can avoid power unit unnecessary shutdown.

Description

Technical Field

[0001] This application relates to the power unit of a high-voltage frequency converter, and more specifically, to a fault operation control system for the power unit of a high-voltage frequency converter and a high-voltage frequency converter including the same. Background Technology

[0002] Currently, there are two common solutions when a power unit in a high-voltage frequency converter fails: one is to directly shut down the drive to protect the equipment and load, and the other is to use an external mechanical bypass device to isolate and bridge the faulty power unit in order to keep the remaining power units working and achieve uninterrupted operation of the high-voltage frequency converter.

[0003] However, the false alarm rate of IGBT failure in the power unit is high. Frequent shutdowns caused by IGBT failures can lead to unnecessary shutdowns of the power unit and high-voltage frequency converter. External mechanical bypass solutions are complex, costly, and cannot guarantee 100% reliability.

[0004] Therefore, a fault operation control system for the power unit of a high-voltage frequency converter with a simple structure is desired, which can avoid unnecessary shutdowns of the power unit and the high-voltage frequency converter without relying on complex external mechanical bypasses and has high reliability. Utility Model Content

[0005] This application is made in view of the above-mentioned problems. The main objective of this application is to provide a fault operation control system for the power unit of a high-voltage frequency converter, so as to solve the technical problem in the prior art that it is difficult to provide a fault operation control system for the power unit of a high-voltage frequency converter with a simple structure, high reliability, and the ability to minimize unnecessary downtime of the power unit and the high-voltage frequency converter.

[0006] To achieve the above objectives, according to one aspect of this application, a fault operation control system for a power unit of a high-voltage frequency converter is provided. The power unit includes an input rectifier stage, a filter capacitor, an inverter output stage, and four drive units. The positive DC output terminal of the input rectifier stage is connected to the positive terminal of a DC bus, and the negative DC output terminal of the input rectifier stage is connected to the negative terminal of a DC bus. The inverter output stage includes four IGBTs using an H-bridge topology. Each drive unit is connected to one IGBT and configured to receive drive commands indicating IGBT on or off, monitor at least one of the IGBT's voltage, current, and drive state, and output an IGBT fault indication signal when the monitoring result is abnormal. The fault operation control system includes: a first voltage sampling circuit connected to the positive and negative terminals of the DC bus, configured to sample the voltages of the positive and negative terminals of the DC bus and output a first voltage fault indication signal when the sampled voltage is abnormal; and a fault triggering circuit whose input terminals are respectively connected to the output terminals of each drive unit and the output terminal of the first voltage sampling circuit, configured to respond to receiving any IGBT fault indication signal. The system includes a fault trigger signal outputting a fault type indication signal, a fault type determination circuit whose inputs are connected to the outputs of each drive unit and the fault trigger circuit, and is configured to output a fault type signal indicating whether the fault is an IGBT fault or a non-IGBT fault in response to receiving the fault trigger signal; a fault counting circuit comprising four counters, each counter whose input is connected to the output of a corresponding drive unit and the output of the fault type determination circuit, and is configured to count the number of faults of the corresponding IGBT and output a count value in response to the fault type signal indicating an IGBT fault; a threshold comparison circuit comprising four comparators, each comparator whose first input is connected to the output of a counter, and whose second input receives a counting threshold, and each comparator is configured to output the comparison result of the corresponding count value with the counting threshold; and a shutdown control circuit whose input is connected to the output of the threshold comparison circuit, and is configured to output a disconnect command to all drive units in response to the comparison result output by the comparator corresponding to the faulty IGBT in the threshold comparison circuit indicating that the count value is greater than or equal to the counting threshold.

[0007] In this way, by constructing a fault operation control system using the aforementioned connection method among various hardware components, the system can achieve redundant judgment of IGBT faults in the power unit: the fault operation control system only activates the shutdown drive command to stop the power unit and the corresponding high-voltage frequency converter when an IGBT fails and its fault count reaches a threshold number. This increases the redundancy of IGBT fault judgment and reduces unnecessary shutdowns of the power unit and high-voltage frequency converter caused by false IGBT fault alarms. Moreover, the non-stop solution under this redundancy mechanism only requires simple hardware circuit connections, without the need for complex external mechanical bypasses. Furthermore, due to the all-hardware structure, the fault operation control system 100 with the above structure has high response speed and high reliability.

[0008] Furthermore, according to one embodiment of this application, the fault operation control system further includes: a bypass control circuit, the input of which is connected to the output of the fault type judgment circuit, the output of each drive unit, and the output of the threshold comparison circuit. The circuit is configured to, in response to a fault type signal indicating an IGBT fault and a comparison result output by the comparator corresponding to the faulty IGBT in the threshold comparison circuit indicating that the count value is less than a count threshold, output a bypass command indicating conduction to the drive units of two target IGBTs connected to the same DC bus that do not contain the faulty IGBT; and in response to a fault type signal indicating a non-IGBT fault, output a bypass command indicating conduction to the drive units of two IGBTs connected to the same DC bus.

[0009] In this way, when a power unit fails but the IGBT fault count is less than the threshold, the fault operation control system can bypass the power unit to allow the high-voltage frequency converter to continue operating. This reduces unnecessary downtime caused by false alarms due to IGBT faults or recoverable non-IGBT faults in the power unit, improving the availability and continuous operation capability of the high-voltage frequency converter.

[0010] Furthermore, according to one embodiment of this application, the fault operation control system further includes: a bypass status check circuit, whose input terminal is respectively connected to the output terminal of the bypass control circuit and the output terminal of each drive unit, and whose output terminal is connected to the input terminal of the fault triggering circuit. The bypass status check circuit includes a timer and is configured to: start the timer in response to receiving a bypass command from the output terminal of the bypass control circuit; after the timer reaches a predetermined delay time, check whether an IGBT fault indication signal is received from the target drive unit targeted by the bypass command; output a display control signal in response to not receiving an IGBT fault indication signal from the target drive unit; and output a retry trigger signal to the fault triggering circuit in response to receiving an IGBT fault indication signal from any target drive unit.

[0011] In this way, the fault-tolerant control system can achieve closed-loop verification of the bypass function. This not only ensures the reliability of the bypass function, but also automatically triggers a retry process after the bypass function fails, updates the fault count, and makes updated decisions (such as bypassing again or eventually shutting down), thereby further improving the robustness of the system.

[0012] Furthermore, according to one embodiment of this application, the fault operation control system further includes: a second voltage sampling circuit connected to the AC input terminal of the input rectifier stage, configured to sample the AC input voltage of the input rectifier stage and output a second voltage fault indication signal when the sampled voltage is abnormal, wherein the input terminal of the fault triggering circuit is also connected to the output terminal of the second voltage sampling circuit.

[0013] In this way, the system's fault detection range is expanded, enabling it to also monitor and protect against anomalies on the AC input side (such as phase loss, overvoltage, or undervoltage).

[0014] Furthermore, according to one embodiment of this application, the fault triggering circuit is a first logic OR operation circuit.

[0015] In this way, by using OR logic gates or programmable logic devices such as PFGAs, a comprehensive judgment on whether a power unit has malfunctioned can be achieved. The circuit structure is simple, the cost is low, and the response speed is extremely fast.

[0016] Further, according to one embodiment of this application, the fault type determination circuit includes: a second logic OR operation circuit, the input terminals of which are respectively connected to the output terminals of each driving unit; a first logic AND operation circuit, the input terminals of which are respectively connected to the output terminals of the second logic OR operation circuit and the output terminal of the fault triggering circuit; a logic NOT operation circuit, the input terminals of which are connected to the output terminals of the second logic OR operation circuit; and a second logic AND operation circuit, the input terminals of which are respectively connected to the output terminals of the logic NOT operation circuit and the output terminals of the fault triggering circuit; wherein, the output terminal of the first logic AND operation circuit outputs a fault type signal indicating an IGBT fault, and the output terminal of the second logic AND operation circuit outputs a fault type signal indicating a non-IGBT fault.

[0017] In this way, by combining logical OR, logical AND, and logical NOT operations, power unit faults can be accurately classified into IGBT faults and non-IGBT faults. Hardware-based judgment logic also avoids the delays and uncertainties that may arise from software-based judgment.

[0018] Furthermore, according to one embodiment of this application, the shutdown control circuit includes: a third logic OR operation circuit, whose input terminals are respectively connected to the output terminals of four comparators, configured to perform a logic OR operation on the output signals of the four comparators, and whose output terminal is connected to the input terminal of each drive unit.

[0019] In this way, by combining logical OR operations with comparators and counters, it is possible to ensure that a global shutdown command is immediately triggered when the fault count of any IGBT reaches the counting threshold, thus ensuring the safety of the power unit and the high-voltage frequency converter while realizing IGBT fault redundancy judgment.

[0020] According to another aspect of this application, a high-voltage frequency converter is provided. The high-voltage frequency converter includes: multiple power units, each power unit including an input rectifier stage, a filter capacitor, an inverter output stage, and four drive units; the positive DC output terminal of the input rectifier stage is connected to the positive terminal of a DC bus, and the negative DC output terminal of the input rectifier stage is connected to the negative terminal of a DC bus; the inverter output stage includes four IGBTs employing an H-bridge topology; each drive unit is connected to one IGBT and configured to receive drive commands indicating IGBT on or off, monitor at least one of the IGBT's voltage, current, and drive status, and output an IGBT fault indication signal when the monitoring results are abnormal; and the aforementioned fault operation control system for the power units of the high-voltage frequency converter.

[0021] In this way, the high-voltage frequency converter according to this application can achieve redundant judgment of IGBT faults with a simple circuit structure and high reliability, reducing unnecessary shutdowns of power units and high-voltage frequency converters caused by false alarms of IGBT faults.

[0022] Furthermore, according to one embodiment of this application, the multiple power units are divided into three power unit groups, each power unit group including several power units cascaded on the output side.

[0023] In this way, a cascaded high-voltage frequency converter can be realized to provide three-phase variable drive to a high-voltage motor.

[0024] In this embodiment, a fault operation control system for a power unit of a high-voltage frequency converter is provided. The power unit includes an input rectifier stage, a filter capacitor, an inverter output stage, and four drive units. The positive DC output terminal of the input rectifier stage is connected to the positive terminal of the DC bus, and the negative DC output terminal of the input rectifier stage is connected to the negative terminal of the DC bus. The inverter output stage includes four IGBTs using an H-bridge topology. Each drive unit is connected to one IGBT and configured to receive drive commands indicating IGBT on or off, monitor at least one of the IGBT's voltage, current, and drive status, and output an IGBT fault code when the monitoring result is abnormal. The fault indication signal and fault operation control system include: a first voltage sampling circuit, connected to the positive and negative terminals of the DC bus, configured to sample the voltages of the positive and negative terminals of the DC bus and output a first voltage fault indication signal when the sampled voltage is abnormal; a fault triggering circuit, whose input terminals are respectively connected to the output terminals of each drive unit and the output terminal of the first voltage sampling circuit, configured to output a fault triggering signal in response to receiving any IGBT fault indication signal or the first voltage fault indication signal; and a fault type determination circuit, whose input terminals are respectively connected to the output terminals of each drive unit and the fault triggering circuit. The output of the circuit is configured to output a fault type signal indicating whether the fault is an IGBT fault or a non-IGBT fault in response to a received fault trigger signal; the fault counting circuit includes four counters, each counter's input is connected to the output of a corresponding drive unit and the output of the fault type judgment circuit, and is configured to count the number of faults of the corresponding IGBT and output the count value in response to the fault type signal indicating an IGBT fault; the threshold comparison circuit includes four comparators, each comparator's first input is connected to the output of a counter, and each comparator's second input receives a counting threshold. A comparator is configured to output a comparison result between the corresponding count value and the count threshold; a shutdown control circuit, whose input is connected to the output of the threshold comparator circuit, is configured to output a disconnect command to all drive units in response to the comparison result of the comparator outputting the faulty IGBT in the threshold comparator circuit indicating that the count value is greater than or equal to the count threshold. This addresses at least the technical problem in the prior art of avoiding unnecessary shutdown of power units with a simple structure, thereby achieving the technical effect of a fault operation control system for power units of high-voltage frequency converters that can avoid unnecessary shutdown of power units while having an improved circuit structure and high reliability. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0026] Figure 1A power unit for a high-voltage frequency converter and a fault operation control system for the power unit according to an embodiment of this application are shown;

[0027] Figure 2 A power unit for a high-voltage frequency converter and a fault operation control system for the power unit according to an exemplary embodiment of this application are shown.

[0028] Figure 3 It shows Figure 2 Details of the connection between the output of the bypass control circuit and the input of the four drive units.

[0029] The above figures include the following reference numerals:

[0030] 100: Fault-prone operation control system

[0031] 110: First voltage sampling circuit

[0032] 120: Fault Trigger Circuit

[0033] 130: Fault type determination circuit

[0034] 140: Fault Counting Circuit

[0035] 150: Threshold Comparison Circuit

[0036] 160: Shutdown control circuit

[0037] 170: Bypass control circuit

[0038] 180: Bypass status check circuit

[0039] 190: Second voltage sampling circuit

[0040] 200: Power Unit

[0041] 210: Input rectifier stage

[0042] 220: Filter capacitor

[0043] 230: Inverter Output Stage

[0044] 241: First drive unit

[0045] 242: Second drive unit

[0046] 243: Third Drive Unit

[0047] 244: Fourth Drive Unit

[0048] 1000: High-voltage frequency converter

[0049] Q1, Q2, Q3, Q4: IGBT

[0050] T1: First single-phase AC output terminal

[0051] T2: Second single-phase AC output terminal Detailed Implementation

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0054] In this application, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this application.

[0055] The purpose of this application is to provide a fault operation control system for the power unit of a high-voltage frequency converter, so as to solve the technical problem in the prior art that it is difficult to achieve redundant judgment of IGBT faults in the power unit with a simple structure and avoid unnecessary shutdown of the power unit and the high-voltage frequency converter.

[0056] A frequency converter is a power conversion device that uses the switching action of power semiconductor devices to convert industrial frequency power to another frequency. Medium- and large-capacity frequency converters used to drive AC motors with a voltage of 1kV or higher are called high-voltage frequency converters. The rated AC voltage of a high-voltage frequency converter is typically 3kV or higher, such as 3.3kV, 6kV, 10kV, or higher. In this application, frequency converters with a rated voltage of 3kV or higher are referred to as "high-voltage frequency converters".

[0057] A typical structure of a high-voltage frequency converter includes: an input-side phase-shift isolation transformer and its connected rectifier unit; multiple power units constituting the main inverter circuit; a DC bus and its associated pre-charge circuit and protection circuit; a control and drive system (including a central controller and unit-level drivers); a cooling system and mechanical support structure.

[0058] The power unit is the core modular, independently operating power electronic power module that constitutes the high-voltage frequency converter. Each power unit typically includes the following functional circuits: an input rectifier stage, usually a three-phase diode rectifier bridge, which converts the AC power from the secondary winding of the input transformer into DC power; a DC bus, containing a filter capacitor bank, used to stabilize the rectified DC bus voltage and provide energy storage and buffering; and an inverter output stage, typically an H-bridge (single-phase full-bridge) circuit composed of insulated-gate bipolar transistors (IGBTs) and their anti-parallel diodes. This inverter output stage, after receiving pulse-width modulation (PWM) or multi-level modulation strategy command signals from the control system, inverts the DC bus voltage into a single-phase low-voltage AC output. In a multi-level cascaded topology, the outputs of multiple power units are connected in series and superimposed to jointly construct the high-voltage output of each phase of the high-voltage frequency converter.

[0059] Figure 1 A power unit for a high-voltage frequency converter and a fault operation control system for the power unit according to an embodiment of this application are shown. Power unit 200 is one of a plurality of power units in high-voltage frequency converter 1000. (As...) Figure 1 As shown, the power unit 200 includes: an input rectifier stage 210, which can be composed of a three-phase diode rectifier bridge. The input terminals A, B, and C of the input rectifier stage 210 are respectively connected to the independent secondary windings of the transformer to convert the power frequency AC power from the transformer into DC power. The positive DC output terminal of the input rectifier stage 210 is connected to the positive (+) terminal of the DC bus, and the negative DC output terminal of the input rectifier stage 210 is connected to the negative (-) terminal of the DC bus; a filter capacitor 220, connected between the positive (+) terminal and the negative (-) terminal of the DC bus, to suppress DC bus voltage fluctuations and provide transient energy buffering; an inverter output stage 230, connected between the positive (+) terminal and the negative (-) terminal of the DC bus, and the inverter output stage 230 includes a first IGBT Q1 to a fourth IGBT Q4 using an H-bridge topology; and four drive units 241 to 244, including a first drive unit 241 connected to the first IGBT Q1 and a drive unit 244 connected to the IGBT Q4. The second drive unit 242 of Q2 is connected to the third drive unit 243 of IGBT Q3, and the fourth drive unit 244 is connected to IGBT Q4. Each drive unit is configured to receive a drive command indicating to turn on or off the corresponding IGBT, monitor at least one of the voltage, current and drive state of the corresponding IGBT, and output an IGBT fault indication signal when the monitoring result is abnormal.

[0060] In this application, the voltage of the IGBT monitored by the drive unit can be the collector-emitter voltage of the IGBT. In this case, an abnormal monitoring result indicates that the monitored collector-emitter voltage of the IGBT exceeds a preset voltage range. The current of the IGBT monitored by the drive unit can be the current flowing through the emitter of the IGBT. In this case, an abnormal monitoring result indicates that the monitored emitter current of the IGBT exceeds a preset current range. The drive state of the IGBT monitored by the drive unit can refer to whether the on / off state indicated by the drive command received by the drive unit is consistent with the actual on / off state of the IGBT. If the two on / off states are consistent, the IGBT drive state is normal; otherwise, the IGBT drive state is abnormal.

[0061] The first IGBT Q1 to the fourth IGBT Q4 form an H-bridge inverter using an H-bridge topology. The first IGBT Q1 and the second IGBT Q2 form the first bridge arm, and the third IGBT Q3 and the fourth IGBT Q4 form the second bridge arm. Specifically, the first IGBT Q1 and the second IGBT Q2 are connected in series between the positive (+) and negative (-) terminals of the DC bus, forming the first bridge arm; and the third IGBT Q3 and the fourth IGBT Q4 are connected in series between the positive (+) and negative (-) terminals of the DC bus, forming the second bridge arm. In other words, the collector of the first IGBT Q1 is connected to the positive (+) terminal of the DC bus, the emitter of the first IGBT Q1 is connected to the collector of the second IGBT Q2, and the emitter of the second IGBT Q2 is connected to the negative (-) terminal of the DC bus. The collector of the third IGBT Q3 is connected to the positive (+) terminal of the DC bus, the emitter of the third IGBT Q3 is connected to the collector of the fourth IGBT Q4, and the emitter of the fourth IGBT Q4 is connected to the negative (-) terminal of the DC bus.

[0062] Furthermore, the connection between the emitter of the first IGBT Q1 and the collector of the second IGBT Q2 is connected to the first single-phase AC output terminal T1, and the connection between the emitter of the third IGBT Q3 and the collector of the fourth IGBT Q4 is connected to the second single-phase AC output terminal T2. The first single-phase AC output terminal T1 and the second single-phase AC output terminal T2 are respectively connected to the two ends of the load (e.g., a motor). By superposition, multiple power units 200 can jointly construct the phase voltage of the high-voltage frequency converter 1000.

[0063] Next, the circuit structure of the fault operation control system 100 for the power unit 200 of the high-voltage frequency converter of this application will be described in detail. For example... Figure 1As shown, the fault operation control system 100 includes: a first voltage sampling circuit 110, connected to the positive and negative terminals of the DC bus, configured to sample the voltages of the positive and negative terminals of the DC bus and output a first voltage fault indication signal when the sampled voltage is abnormal; a fault triggering circuit 120, whose input terminals are respectively connected to the output terminals of each drive unit and the output terminal of the first voltage sampling circuit, configured to output a fault triggering signal in response to receiving any IGBT fault indication signal or the first voltage fault indication signal; a fault type judgment circuit 130, whose input terminals are respectively connected to the output terminals of each drive unit and the output terminal of the fault triggering circuit, configured to output a fault type signal indicating whether the fault is an IGBT fault or a non-IGBT fault in response to receiving the fault triggering signal; and a fault counting circuit. The counting circuit 140 includes four counters, each with its input connected to the output of a corresponding drive unit and the output of a fault type determination circuit. It is configured to count the number of faults of the corresponding IGBT and output a count value in response to a fault type signal indicating an IGBT fault. The threshold comparison circuit 150 includes four comparators, each with its first input connected to the output of a counter and its second input receiving a counting threshold. Each comparator is configured to output a comparison result between the corresponding count value and the counting threshold. The shutdown control circuit 160, with its input connected to the output of the threshold comparison circuit, is configured to output a disconnect command to all drive units in response to a comparison result from the comparator corresponding to the faulty IGBT indicating that the count value is greater than or equal to the counting threshold.

[0064] In this application, the first voltage sampling circuit 110, fault triggering circuit 120, fault type judgment circuit 130, fault counting circuit 140, threshold comparison circuit 150, and shutdown control circuit 160 in the fault operation control system 100 are all hardware devices. By constructing the fault operation control system 100 with the above-described connection method using hardware devices, the system 100 can achieve redundant judgment of IGBT faults in the power unit: the fault operation control system 100 only activates the shutdown drive command to shut down the power unit and the corresponding high-voltage frequency converter when a fault occurs in a certain IGBT and the fault count of that IGBT reaches the threshold number of times. This increases the redundancy of IGBT fault judgment and can reduce unnecessary shutdowns of the power unit and high-voltage frequency converter caused by false IGBT faults. Moreover, the non-stop shutdown scheme under this redundancy mechanism only requires simple hardware circuit connections and does not require complex external mechanical bypasses. In addition, due to the use of a fully hardware structure, the fault operation control system 100 with the above-described structure has high response speed and high reliability.

[0065] In this application, the preset counting threshold Th can be a positive integer that needs to be set, such as 2, 3, 4, etc. The preset counting threshold Th can be output to one input of the comparator through a hardware DIP switch or a register.

[0066] Next, refer to Figure 2 and Figure 3 An exemplary embodiment of the fault operation control system 100 according to this application is described. Figure 2 The fault operation control system 100 shown is in Figure 1 Based on the fault operation control system shown, new hardware components have been added. Figure 3 It shows Figure 2 The connection details between the output of the bypass control circuit and the inputs of the four drive units are detailed below. Figure 2 The middle part is omitted to make the diagram clearer.

[0067] like Figure 2 As shown, the fault operation control system 100 may further include a bypass control circuit 170, the input of which is connected to the output of the fault type determination circuit 130, the output of each drive unit, and the output of the threshold comparison circuit 150. The bypass control circuit 170 is configured to: in response to a fault type signal indicating an IGBT fault, and the comparison result output by the comparator corresponding to the faulty IGBT in the threshold comparison circuit indicating a count value less than a count threshold, output a bypass command indicating conduction to the drive units of two target IGBTs connected to the same DC bus that do not contain the faulty IGBT; and in response to a fault type signal indicating a non-IGBT fault, output a bypass command indicating conduction to the drive units of two IGBTs connected to the same DC bus.

[0068] Therefore, by utilizing a bypass control circuit, when a power unit experiences a non-IGBT fault, or an IGBT fault but the fault count is less than the threshold, the current power unit can be bypassed from the high-voltage inverter by conducting two IGBTs connected to the same DC bus, while the high-voltage inverter continues to operate. This bypass function reduces unnecessary downtime for both the power unit and the high-voltage inverter. Furthermore, implementing the bypass function with a simple hardware topology ensures high reliability.

[0069] Furthermore, the fault operation control system 100 may further include a bypass status check circuit 180, whose input terminals are respectively connected to the output terminals of the bypass control circuit and the output terminals of each drive unit, and whose output terminal is connected to the input terminal of the fault trigger circuit 120. The bypass status check circuit 180 includes a timer and is configured to: start the timer in response to receiving a bypass command from the output terminal of the bypass control circuit; after the timer reaches a predetermined delay time, check whether an IGBT fault indication signal has been received from the target drive unit targeted by the bypass command; output a display control signal in response to not receiving an IGBT fault indication signal from the target drive unit; and output a retry trigger signal to the fault trigger circuit in response to receiving an IGBT fault indication signal from any target drive unit. For example, the display control signal may instruct the display unit to output a planned shutdown prompt signal.

[0070] Furthermore, the fault operation control system 100 may also include: a second voltage sampling circuit 190, connected to the AC input terminal of the input rectifier stage, configured to sample the AC input voltage of the input rectifier stage and output a second voltage fault indication signal indicating a second voltage fault when the sampled voltage is abnormal, wherein the input terminal of the fault triggering circuit 120 is also connected to the output terminal of the second voltage sampling circuit 190. In this case, the fault triggering circuit 120 can perform a logical OR operation on the signals output by each drive unit, the signal output by the first voltage sampling circuit 110, and the signal output by the second voltage sampling circuit 190.

[0071] Next, the specific structure and connection topology of the fault triggering circuit 120, fault type judgment circuit 130, fault counting circuit 140, threshold comparison circuit 150, shutdown control circuit 160, bypass control circuit 170 and bypass status check circuit 180 are described.

[0072] The fault triggering circuit 120 may be a first logic OR operation circuit, which performs a logic OR operation on all received input signals to determine whether there is a fault in the power unit 200.

[0073] In the event of a fault in the power unit 200, the fault type determination circuit 130 determines the type of fault. To this end, the fault type determination circuit 130 may include: a second logic OR operation circuit, whose inputs are respectively connected to the outputs of each drive unit; a first logic AND operation circuit, whose inputs are respectively connected to the outputs of the second logic OR operation circuit and the fault triggering circuit; a logic NOT operation circuit, whose inputs are connected to the output of the second logic OR operation circuit; and a second logic AND operation circuit, whose inputs are respectively connected to the outputs of the logic NOT operation circuit and the fault triggering circuit. In other words, the fault type determination circuit 130 may include a first output (the output of the first logic AND operation circuit) and a second output (the output of the second logic AND operation circuit). The first output can output a fault type signal indicating an IGBT fault, while the second output can output a fault type signal indicating a non-IGBT fault.

[0074] The fault counting circuit 140 may include four counters. The clock input of each counter can be connected to the first output of the fault type determination circuit 130, and the enable input of each counter can be connected to the output of a corresponding drive unit.

[0075] The threshold comparison circuit 150 may include four comparators. Each comparator corresponds to an IGBT and its driving unit. Each comparator can be configured to output a high-level comparison result signal in response to the count value of the corresponding counter being greater than or equal to the count threshold Th (or reaching the count threshold).

[0076] The shutdown control circuit 160 is used to output a disconnect command to all drive units when the comparison result of the comparator outputting the faulty IGBT indicates that the count value is greater than or equal to a counting threshold. To this end, the shutdown control circuit 160 may include a third logic OR operation circuit, whose inputs are respectively connected to the outputs of four comparators, configured to perform a logic OR operation on the output signals of the four comparators, and whose output is connected to the input of each drive unit, for outputting the disconnect command indicating the disconnection of the corresponding IGBT to each drive unit. Thus, when the comparison result of any comparator indicates that the count value of the corresponding faulty IGBT is greater than or equal to the counting threshold Th, the shutdown control circuit 160 can output a disconnect command indicating the disconnection of all IGBTs.

[0077] The bypass control circuit 170 outputs a bypass command to the corresponding IGBT drive unit when the bypass condition is met but the shutdown condition is not met. For this purpose, the bypass control circuit 170 may include: a first bypass logic OR operation circuit, whose inputs are connected to the outputs of the first drive unit 241 and the third drive unit 243, respectively; and a second bypass logic OR operation circuit, whose inputs are connected to the outputs of the second drive unit 242 and the fourth drive unit 244, respectively. Thus, the output signals of the first and second bypass logic OR operation circuits can be considered polarity fault signals, indicating which two IGBTs should be turned on to achieve bypass. For example, when one of the first drive unit 241 and the third drive unit 243 outputs an IGBT fault indication signal, the first bypass logic OR operation circuit can output a high-level polarity fault signal, indicating that the fault is located on the positive side of the DC bus. This means that to perform the bypass function, the second IGBT Q2 and the fourth IGBT Q4 should be turned on.

[0078] The bypass control circuit 170 may further include: a bypass logic NOT circuit, the input of which is connected to the output of the third logic OR circuit of the stop control circuit 160; and a first bypass logic AND circuit, the input of which is connected to the output of the bypass logic NOT circuit and the output of the first logic AND circuit in the fault type determination circuit 120. The high-level signal output by the first bypass logic AND circuit can be considered a bypass enable signal. For example, when the output of the third logic OR circuit of the stop control circuit 160 outputs a low-level signal (indicating that the fault count of all IGBTs has not reached the counting threshold Th), and the output of the first logic AND circuit in the fault type determination circuit 130 outputs a high-level signal (indicating that an IGBT fault has occurred), the first bypass logic AND circuit will output a bypass enable signal to enable the bypass function. Thus, when an IGBT fault occurs and the IGBT fault count has not reached the counting threshold, the bypass function is enabled.

[0079] The bypass control circuit 170 may further include a second bypass logic AND operation circuit and a third bypass logic AND operation circuit. The input terminals of the second bypass logic AND operation circuit are respectively connected to the output terminals of the first bypass logic OR operation circuit and the first bypass logic AND operation circuit. The output terminals of the second bypass logic AND operation circuit are respectively connected to the input terminals of the second drive unit 242 and the fourth drive unit 244 to output bypass commands to the second drive unit 242 and the fourth drive unit 244. Correspondingly, the input terminals of the third bypass logic AND operation circuit are respectively connected to the output terminals of the second bypass logic OR operation circuit and the first bypass logic AND operation circuit. The output terminals of the third bypass logic AND operation circuit are respectively connected to the input terminals of the first drive unit 241 and the third drive unit 243 to output bypass commands to the first drive unit 241 and the third drive unit 243.

[0080] Therefore, for example, when the first IGBT Q1 fails, but the count value of the corresponding counter is less than the count threshold Th, the first bypass logic AND operation circuit will output a bypass enable signal and the first bypass logic OR operation circuit will output a polarity fault signal. Consequently, the second bypass logic AND operation circuit will output a high-level bypass command (i.e., a drive command indicating conduction) to the second drive unit 242 and the fourth drive unit 244, thereby turning on the second IGBT Q2 and the fourth IGBT Q4. Thus, the power unit 200 is bypassed, while the high-voltage frequency converter 1000, including this power unit and other power units, can continue to operate without shutting down.

[0081] The bypass status check circuit 180 is used to check whether the IGBT that received the bypass command is faulty after the bypass control circuit 170 outputs the bypass command. To this end, the bypass status check circuit 180 may include a timer, the input of which is connected to the output of the first bypass logic AND operation circuit. The timer is configured to start when a bypass enable signal is received and output a timing completion signal after a predetermined delay time (e.g., 12μs).

[0082] The bypass status check circuit 180 may further include four check enable logic circuits, each of which can be a logic AND operation circuit. The input of each check enable logic circuit is connected to the output of a timer, and one of the four outputs of the second and third bypass logic AND operation circuits, respectively. Thus, each check enable logic circuit actually corresponds to one IGBT and its driving unit, and can be used to output a check enable signal indicating that the bypass status check is enabled. For example, when the second bypass logic AND operation circuit outputs a bypass command to the second driving unit 242 and the fourth driving unit 244, the corresponding two check enable logic circuits will output a high-level check enable signal indicating that the bypass status check is enabled.

[0083] The bypass status check circuit 180 may further include four status check logic circuits and one logic OR operation circuit. Each status check logic circuit may be a logic AND operation circuit. The input of each status check logic circuit is connected to the output of a check enable logic circuit and the output of the corresponding IGBT driver unit. The output of each status check logic circuit is connected to the input of the logic OR operation circuit. The output of the logic OR operation circuit is connected to one input of the fault trigger circuit 120. The logic OR operation circuit is used to detect whether the output signal of any status check logic circuit is high, and outputs a high-level retry trigger signal to the fault trigger circuit 120 when the output signal of any status check logic circuit is high. At this time, the fault trigger circuit 120 is configured to perform a logic OR operation on the signals output by each driver unit, the signal output by the first voltage sampling circuit 110, the second voltage sampling circuit 190 (if present), and the signal output by the bypass status check circuit 180.

[0084] Furthermore, the bypass status check circuit 180 may also include a display control logic circuit, which may include a logic OR circuit and a logic NOT circuit. The input terminals of the logic OR circuit are connected to the output terminals of all status check logic circuits to detect whether any retry trigger signal is output. The input terminal of the logic NOT circuit is connected to the output terminal of the logic OR circuit, and the output terminal of the logic NOT circuit outputs a display control signal. Thus, when the timer delays for a predetermined time and no retry trigger signal is output, the display control logic circuit outputs a display control signal.

[0085] In this application, the first voltage sampling circuit 110 can be implemented by a resistor divider network combined with an isolation operational amplifier (such as ISO124) and a voltage comparator (such as LM393), or it can be implemented using a dedicated analog-to-digital converter (ADC) chip (such as AD4003). The DC bus voltage sampled by the DC voltage sampling circuit 150 can be used to compare with the DC bus voltage threshold range to determine whether there is overvoltage or undervoltage (i.e., whether it is abnormal).

[0086] In this application, the second voltage sampling circuit 190 can be connected to the three AC input terminals of the input rectifier stage 210 respectively to sample the AC input voltage. The three-phase AC input voltage sampled by the second voltage sampling circuit 190 can be compared with an AC input voltage threshold or threshold range to determine whether the AC input voltage is missing a phase (i.e., abnormal). For example, the second voltage sampling circuit 190 may include three voltage transformers, three voltage comparators, and an OR gate circuit to output a second voltage fault indication signal when an abnormality in the input voltage of any phase is sensed.

[0087] In this application, each of the fault triggering circuit 120, fault type judgment circuit 130, fault counting circuit 140, threshold comparison circuit 150, shutdown control circuit 160, bypass control circuit 170, and bypass status check circuit 180 (including the logic OR circuit, logic AND circuit, comparator, counter, timer, etc. therein) can be composed of general logic gate circuits (such as 74HC32 OR gate, 74HC08 AND gate, 74HC04 NOT gate) according to the required logical relationship; alternatively, it can also be configured by the logic resources inside a programmable logic device (such as FPGA or CPLD or ASIC or other programmable logic device).

[0088] Furthermore, the fault operation control system 100 may also include a temperature sampling unit (not shown). This temperature sampling unit can be attached to the circuit board containing the four IGBTs and positioned between the four IGBTs to monitor the temperature of the power unit and output a temperature fault indication signal when the monitored temperature exceeds a temperature threshold range. At this time, the input terminal of the fault triggering circuit 120 can also be connected to the output terminal of the temperature sampling unit, and perform a logical OR operation on the signals received from each drive unit, the first voltage sampling circuit 110, the second voltage sampling circuit 190, and the temperature sampling unit.

[0089] Furthermore, this application also provides a high-voltage frequency converter 1000, which includes a plurality of power units 200 as described above and a fault operation control system 100 for the power units of the high-voltage frequency converter according to this application. Further, the plurality of power units can be divided into three power unit groups (corresponding to the three phases of the transformer respectively), and each power unit group can include several power units cascaded on the output side. Thus, a cascaded high-voltage frequency converter for providing three-phase variable drive to a high-voltage motor can be realized.

[0090] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0091] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Nouns and pronouns relating to persons in this patent application are not limited to specific genders.

[0092] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fault operation control system for a power unit of a high-voltage frequency converter, the power unit (200) comprising an input rectifier stage (210), a filter capacitor (220), an inverter output stage (230), and four drive units (241, 242, 243, 244), wherein the positive DC output terminal of the input rectifier stage (210) is connected to the positive terminal of a DC bus, and the negative DC output terminal of the input rectifier stage is connected to the negative terminal of a DC bus; the inverter output stage comprises four IGBTs using an H-bridge topology; each drive unit is connected to one IGBT and configured to receive drive commands indicating the IGBT to be turned on or off, monitor at least one of the voltage, current, and drive status of the IGBT, and output an IGBT fault indication signal when the monitoring result is abnormal, characterized in that... The fault operation control system (100) includes: A first voltage sampling circuit (110) is connected to the positive terminal of the DC bus and the negative terminal of the DC bus, and is configured to sample the voltage of the positive terminal of the DC bus and the negative terminal of the DC bus and output a first voltage fault indication signal when the sampled voltage is abnormal. A fault triggering circuit (120) has its input terminals connected to the output terminals of each of the driving units and the output terminal of the first voltage sampling circuit, respectively. The fault triggering circuit is configured to output a fault triggering signal in response to receiving any of the IGBT fault indication signals or the first voltage fault indication signal. The fault type determination circuit (130), whose input terminal is connected to the output terminal of each of the drive units and the output terminal of the fault trigger circuit (120), is configured to output a fault type signal indicating whether the fault is an IGBT fault or a non-IGBT fault in response to receiving the fault trigger signal. The fault counting circuit (140) includes four counters, the input of each counter is connected to the output of a corresponding drive unit and the output of the fault type judgment circuit (130), and is configured to count the number of faults of the corresponding IGBT and output the count value in response to the fault type signal indicating an IGBT fault. The threshold comparison circuit (150) includes four comparators, each of which has a first input connected to the output of a counter, and a second input of each comparator receiving a counting threshold. Each comparator is configured to output a comparison result between the corresponding count value and the counting threshold. A shutdown control circuit (160), whose input is connected to the output of the threshold comparison circuit (150), is configured to output a disconnect command to all drive units in response to a comparison result in the comparator output of the threshold comparison circuit (150) corresponding to the faulty IGBT indicating that the count value is greater than or equal to the count threshold.

2. The fault run control system of a power cell for a high voltage frequency converter according to claim 1, characterized in that, The fault operation control system (100) also includes: A bypass control circuit (170), whose input is connected to the output of the fault type determination circuit (130), the output of each of the drive units, and the output of the threshold comparison circuit (150), is configured to, in response to the fault type signal indicating an IGBT fault and the comparison result output by the comparator in the threshold comparison circuit corresponding to the faulty IGBT indicating that the count value is less than the count threshold, output a bypass command indicating conduction to the drive units of two target IGBTs connected to the same DC bus and not containing the faulty IGBT, and in response to the fault type signal indicating a non-IGBT fault, output the bypass command indicating conduction to the drive units of two IGBTs connected to the same DC bus.

3. The fault operation control system for the power unit of a high-voltage frequency converter according to claim 2, characterized in that, The fault operation control system (100) also includes: A bypass status check circuit (180) has its input terminals connected to the output terminals of the bypass control circuit (170) and each of the drive units, respectively, and its output terminal connected to the input terminal of the fault triggering circuit (120). The bypass status check circuit (180) includes a timer and is configured to: In response to receiving the bypass command from the output of the bypass control circuit (170), the timer is started; After the timer reaches a predetermined delay time, check whether an IGBT fault indication signal is received from the target drive unit targeted by the bypass command; In response to the failure to receive an IGBT fault indication signal from the target drive unit, a display control signal is output; In response to receiving an IGBT fault indication signal from any of the target drive units, a retry trigger signal is output to the fault trigger circuit (120).

4. The fault run control system for a power cell of a high voltage variable frequency drive of claim 1, wherein, The fault operation control system (100) also includes: The second voltage sampling circuit (190), connected to the AC input terminal of the input rectifier stage, is configured to sample the AC input voltage of the input rectifier stage and output a second voltage fault indication signal when the sampled voltage is abnormal. The input terminal of the fault triggering circuit (120) is also connected to the output terminal of the second voltage sampling circuit (190).

5. The fault run control system of a power cell for a high voltage variable frequency drive of any of claims 1 to 4, characterized in that, The fault triggering circuit (120) is a first logic OR operation circuit.

6. The fault run control system of a power cell for a high voltage variable frequency drive of any of claims 1 to 4, characterized in that, The fault type determination circuit (130) includes: The second logic OR operation circuit has its input terminals connected to the output terminals of each of the driving units; The first logic AND operation circuit has its input terminals connected to the output terminals of the second logic OR operation circuit and the output terminals of the fault triggering circuit (120), respectively. A logic NOT circuit, the input of which is connected to the output of the second logic OR circuit; and The second logic AND operation circuit has its input terminals connected to the output terminal of the logic NOT operation circuit and the output terminal of the fault triggering circuit (120), respectively. The first logic AND operation circuit outputs a fault type signal indicating an IGBT fault, and the second logic AND operation circuit outputs a fault type signal indicating a non-IGBT fault.

7. The fault run control system of a power cell for a high voltage variable frequency drive of any of claims 1 to 4, characterized in that, The shutdown control circuit (160) includes: The third logic OR operation circuit, whose input terminals are respectively connected to the output terminals of the four comparators, is configured to perform a logic OR operation on the output signals of the four comparators, and whose output terminal is connected to the input terminal of each of the driving units.

8. A high voltage frequency converter, characterized in that The high-voltage frequency converter (1000) includes: The system comprises multiple power units, each including an input rectifier stage, a filter capacitor, an inverter output stage, and four drive units. The positive DC output terminal of the input rectifier stage is connected to the positive terminal of the DC bus, and the negative DC output terminal of the input rectifier stage is connected to the negative terminal of the DC bus. The inverter output stage includes four IGBTs using an H-bridge topology. Each drive unit is connected to one IGBT and configured to receive drive commands indicating whether the IGBT is turned on or off, monitor at least one of the IGBT's voltage, current, and drive status, and output an IGBT fault indication signal when the monitoring results are abnormal. Fault operation control system for power unit of high voltage frequency converter according to any one of claims 1 to 7.

9. The high voltage frequency converter of claim 8, wherein, The plurality of power units are divided into three power unit groups, and each power unit group includes a plurality of power units cascaded on the output side.

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