Fault detection method and device, equipment and storage medium

Abstract

The invention provides a fault detection method and device, equipment and a storage medium, relates to the technical field of electronic circuits, solves the problem that the detection of the fault condition of a three-phase motor is not accurate enough in the related technology, and can rapidly judge the on-off condition of IGBTs (Insulated Gate Bipolar Translator) of an upper half bridge of a frequency conversion board as upper and lower tubes through the collection of three-phase current, thereby improving the detection accuracy of the three-phase motor. And whether the three-phase electric phase line is missing or not can be quickly judged, and efficient and accurate fault detection is realized.

Description

Technical Field

[0001] This application relates to the technical field of electronic circuits, and particularly to a fault detection method, device, equipment, and storage medium. Background Art

[0002] The traditional variable-frequency board controls the IPM (Intelligent Power Module) through the FOC (Field-Oriented Control) algorithm to control the on / off of any IGBT (Insulate-Gate Bipolar Transistor) serving as the upper or lower tube in the IGBT inverter circuit, so as to realize the operation of the three-phase motor. In practical applications, during the operation of the three-phase motor, when a certain phase line is missing or a certain IGBT is damaged, the three-phase motor can still operate normally. However, these situations will cause the imbalance between the maximum and minimum values of the phase current. Moreover, as the motor speed increases, the gap between the maximum and minimum values of the phase current becomes larger and larger. Long-term operation will lead to an overcurrent risk in the variable-frequency board, damage the IPM module, and cause wear to the motor rotor.

[0003] In this regard, it is necessary to detect the fault conditions (such as the above-mentioned phase loss or IGBT damage) of the three-phase motor. For example, in the related art, the phase currents are usually sampled to determine whether there is a fault condition according to the effective current value. However, this method is prone to misjudgment, resulting in inaccurate detection of the fault condition. Summary of the Invention

[0004] This application provides a fault detection method, device, equipment, and storage medium, which solves the problem of inaccurate detection of the fault conditions of the three-phase motor in the related art. This solution can quickly determine the on / off conditions of the IGBTs serving as the upper and lower tubes on the upper half-bridge of the variable-frequency board by collecting the three-phase currents, and can quickly determine whether there is a missing phase line in the three-phase electricity, realizing efficient and accurate fault detection.

[0005] In a first aspect, this application provides a fault detection method, which is applied to a detection device. The detection device is connected to a variable-frequency board. The variable-frequency board is used to drive the connected three-phase motor. The detection device is used to supply power to the variable-frequency board to control the IGBT on the variable-frequency board to provide three-phase currents for the three-phase motor. The fault detection method includes:

[0006] Determine whether the control stage in which the three-phase motor is located belongs to an open-loop control stage or a closed-loop control stage according to the output current provided to the variable-frequency board;

[0007] Based on the control stage in which the three-phase motor is located, determine the determination time and the minimum current threshold associated with the control stage;

[0008] Monitor the three-phase current on the variable-frequency board, and record the first over-limit times when the amplitude of each phase current in the three-phase current corresponding to the positive half-cycle is greater than the minimum current threshold and the second over-limit times when the amplitude corresponding to the negative half-cycle is greater than the minimum current threshold within the determination time;

[0009] Based on the first over-limit times, the second over-limit times, and the phase current amplitude corresponding to each phase current in the three-phase current, perform open-phase detection and damage detection on the variable-frequency board respectively to determine the fault state of the variable-frequency board.

[0010] In a second aspect, the present application provides a fault detection device, which is applied to a detection device. The detection device is connected to the variable-frequency board. The variable-frequency board is used to drive the connected three-phase motor. The detection device is used to supply power to the variable-frequency board to control the IGBT on the variable-frequency board to provide three-phase current for the three-phase motor. The fault detection device includes:

[0011] A stage detection module, configured to determine whether the control stage of the three-phase motor belongs to an open-loop control stage or a closed-loop control stage according to the output current provided to the variable-frequency board;

[0012] A threshold determination module, configured to determine the determination time and the minimum current threshold associated with the control stage based on the control stage of the three-phase motor;

[0013] A current monitoring module, configured to monitor the three-phase current on the variable-frequency board, and record the first over-limit times when the amplitude of each phase current in the three-phase current corresponding to the positive half-cycle is greater than the minimum current threshold and the second over-limit times when the amplitude corresponding to the negative half-cycle is greater than the minimum current threshold within the determination time;

[0014] A fault judgment module, configured to perform open-phase detection and damage detection on the variable-frequency board respectively according to the first over-limit times, the second over-limit times, and the phase current amplitude corresponding to each phase current in the three-phase current to determine the fault state of the variable-frequency board.

[0015] In a third aspect, the present application further provides a detection device, which includes:

[0016] One or more processors;

[0017] A storage device for storing one or more programs,

[0018] When the one or more programs are executed by the one or more processors, the one or more processors implement the fault detection method of the present application.

[0019] In a fourth aspect, the present application further provides a storage medium storing computer-executable instructions, and the computer-executable instructions are used to execute the fault detection method of the present application when executed by a processor.

[0020] In the solution of this application, different determination times and minimum current thresholds are selected according to different control stages of the three-phase motor, and then the phase current is detected. By utilizing the characteristics of the phase currents of the three-phase motor during operation and setting the determination time and minimum current threshold for different control stages, this solution can accurately and quickly detect the faults occurring in the frequency conversion board, thereby timely detecting the faults of the frequency conversion board, reducing the overcurrent risk, and also helping to reduce the occurrence of misjudgment, improving the accuracy of fault detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the principle of the IGBT inverter circuit in the related art;

[0022] Figure 2 It is a schematic diagram of the current change of the upper and lower tubes corresponding to one phase in the three-phase motor when the IGBT serving as the lower tube is damaged;

[0023] Figure 3 It is a schematic diagram of the steps of the fault detection method provided by an embodiment of this application;

[0024] Figure 4 It is a schematic diagram of the current change in the open-loop control stage and the closed-loop control stage provided by an embodiment of this application;

[0025] Figure 5 It is a schematic diagram of the steps of detecting the fault state of the frequency conversion board provided by an embodiment of this application;

[0026] Figure 6 It is a schematic diagram of the structure of the fault detection device provided by an embodiment of this application;

[0027] Figure 7 It is a schematic diagram of the structure of the detection device provided by an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following further elaborates on the embodiments of this application in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the embodiments of this application, rather than limiting the embodiments of this application. Additionally, it should be noted that for ease of description, only parts related to the embodiments of this application are shown in the drawings, rather than all structures. Those skilled in the art should be able to think that as long as the technical features do not conflict with each other, any combination of technical features can constitute an optional implementation manner after reading the specification of this application.

[0029] The terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of this application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally means that the related objects before and after are in an "or" relationship. In the description of this application, "a plurality" means two or more, and "several" means one or more.

[0030] On the variable-frequency board, the operation control of the three-phase motor is realized by controlling the IGBT inverter circuit, as Figure 1 shown, Figure 1 is a schematic diagram of the principle of the IGBT inverter circuit in the related art. Among them, six IGBTs are provided, namely Q1-Q6 in the figure, and two IGBTs are taken as a group to correspond to one of the three phases of the three-phase motor (such as M in the figure), and the IGBTs in each group are divided into an upper tube and a lower tube. It can be imagined that the upper tube corresponds to the circuit path in the positive half-cycle of the positive current for this phase, and the lower tube corresponds to the current path in the negative half-cycle of the negative current for this phase. In this regard, the IPM module is controlled by the FOC algorithm to realize the control of the IGBT inverter circuit.

[0031] Figure 2 is a schematic diagram of the current change of the upper tube and the lower tube corresponding to one phase in the three-phase motor in the case where the IGBT serving as the lower tube is damaged, as Figure 2 shown, half of the waveform is missing in the obtained current, and the current corresponding to the negative half-cycle is missing. In this regard, it can be considered that the IGBT serving as the lower tube is damaged. In practical applications, when a certain phase line is missing (i.e., phase loss) or a certain IGBT is damaged during the operation of the three-phase motor, the three-phase motor can still operate normally, but these situations will cause the maximum and minimum values of the phase current to be unbalanced, and as the motor speed increases, the gap between the maximum and minimum values of the phase current becomes larger and larger. Long-term operation will cause the variable-frequency board to have an overcurrent risk, damage the IPM module, and cause wear to the motor rotor.

[0032] In this regard, this application provides a fault detection method, which is applied to a detection device. The detection device is connected to the variable-frequency board. It can be imagined that the detection device can supply power to the variable-frequency board to realize the control of the IGBT on the variable-frequency board, so that the variable-frequency board can provide three-phase current for the three-phase motor connected thereto, and then drive the three-phase motor. Of course, the detection device can also complete the fault detection of the variable-frequency board during the process of supplying power to the variable-frequency board.

[0033] In the embodiment of the present application, the detection device detects the control stage of the three-phase motor and adopts different detection criteria to achieve the fault detection of the frequency conversion board, such as Figure 3 shown Figure 3 is a schematic diagram of the steps of the fault detection method provided by an embodiment of the present application. The corresponding steps include steps S110-S140:

[0034] Step S110: Determine whether the control stage of the three-phase motor belongs to the open-loop control stage or the closed-loop control stage according to the output current provided to the frequency conversion board.

[0035] It can be understood that the detection device can provide a corresponding output current so that the frequency conversion board outputs a corresponding three-phase current to the three-phase motor. The operation process of the three-phase motor can be divided into two different control stages, corresponding to the open-loop control stage of static start and the closed-loop control stage of normal operation. Figure 4 is a schematic diagram of the current change in the open-loop control stage and the closed-loop control stage provided by an embodiment of the present application. As shown in the figure, in the open-loop control stage and the closed-loop control stage, the three-phase currents required by the three-phase motor are different, and the output currents provided by the detection device are also different. For example, in the open-loop control stage, the current is large and the period is short, and it needs to be maintained for a period of time; while in the closed-loop control stage, the current changes with the speed of the three-phase motor. Therefore, by detecting the output current, the control stage of the three-phase motor can be determined. Therefore, there is a situation where the current in the open-loop control stage is greater than the current in the closed-loop control stage. In Figure 4 the process where the current changes from a large amplitude to a small amplitude corresponds to the process of switching from the open-loop control stage to the closed-loop control stage.

[0036] Step S120: Based on the control stage of the three-phase motor, determine the determination time and the minimum current threshold associated with the control stage.

[0037] It can be imagined that the detection device adopts different detection strategies for different control stages, such as different determination times and minimum current thresholds determined. Therefore, after determining the control stage of the three-phase motor, correspondingly, the corresponding determination time and minimum current threshold can be determined.

[0038] Optionally, in one embodiment, when the three-phase motor is in the open-loop control stage, the output current is the starting current, which is used to drive the three-phase motor to start running from a stationary state. Therefore, when it is determined that the current output current is the starting current, it can be determined that the three-phase motor is in the open-loop control stage. For the three-phase motor in the open-loop control stage, the detection device can calculate the amplitude of the starting current according to a preset ratio to determine the minimum current threshold. For example, the preset ratio is 3:4, that is, the ratio of the minimum current threshold to the amplitude of the starting current is 3:4. Then, based on the amplitude of the starting current and this preset ratio, the specific value of the minimum current threshold can be determined. In addition, in the open-loop control stage, a starting current needs to be provided for a period of time for the control of the three-phase motor. This period of time is called the maintenance time. That is, within the maintenance time, the detection device provides a large starting current so that the three-phase motor can start. Therefore, the detection device takes the maintenance time of the starting current as the upper limit duration of the determination time, and then sets the specific value of the determination time. For example, 90% of the maintenance time is used as the specific duration of the determination time.

[0039] It should be noted that, in one embodiment, the determination time should also be greater than or equal to one current cycle of the starting current, where one current cycle includes a positive half-cycle and a negative half-cycle, so that there is at least one positive half-cycle and one negative half-cycle within the determination time, which is convenient for detecting the current of the current phase. In this regard, for the open-loop control stage, the specific value of the determination time can be set according to actual application requirements, and the selected determination time is greater than or equal to the current cycle of the starting current and less than or equal to the maintenance time of the starting current.

[0040] Optionally, in one embodiment, when the three-phase motor is in the closed-loop control stage, the output current provided by the detection device is the operating current, which is used to drive the three-phase motor to operate at a target speed, that is, the magnitude of the operating current is related to the target speed set by the user. Therefore, when it is determined that the three-phase motor is currently in the closed-loop control stage, the detection device can select the minimum phase current of the three-phase motor in the no-load state or the minimum speed state as the minimum current threshold. Among them, the minimum phase current in the no-load state or the minimum speed state is the current value corresponding to the smallest one of the phase currents corresponding to the three phases. It can be understood that for the three-phase motor in the closed-loop control stage, the no-load state corresponds to the state when the three-phase motor starts to operate without carrying devices such as blades or gears. The minimum phase current in this state can be obtained through pre-testing or pre-setting in the detection device for easy acquisition during the detection process. The minimum speed state corresponds to the state when the three-phase motor is at the lowest speed when it can operate normally. Similarly, the minimum phase current in this state can be obtained through pre-testing or pre-setting in the detection device for easy acquisition during the detection process.

[0041] For the determination time set for the three-phase motor in the closed-loop control stage, the detection device determines the corresponding overshoot recovery time based on the duration during which the speed of the three-phase motor is lower than the preset speed during the process of reducing from the target speed to the preset speed. It can be understood that in practical applications, during the process of controlling the three-phase motor to reduce its speed, due to inertia, the speed of the three-phase motor cannot immediately stabilize at the preset speed, and there will be a period of time when the speed is lower than the preset speed, that is, there is an overshoot recovery time. And to avoid misjudgment of overshoot, the determined overshoot recovery time is used as the lower limit duration to set the determination time, that is, the set determination time is greater than or equal to the overshoot recovery time. For example, it is set to 1.5 times the overshoot recovery time. It should be noted that for the closed-loop control stage, the specific value of the determination time can be set according to actual application requirements, as long as it is greater than or equal to the overshoot recovery time.

[0042] Therefore, by setting the corresponding determination time and the minimum current threshold, the detection device can detect the current within the corresponding judgment time for different control stages, and determine the fault condition of the frequency conversion board based on the minimum current threshold, so as to achieve efficient and accurate fault detection.

[0043] Step S130: Monitor the three-phase current on the frequency conversion board, and record the first overlimit times when the amplitude of each phase current in the positive half-cycle is greater than the minimum current threshold and the second overlimit times when the amplitude of each phase current in the negative half-cycle is greater than the minimum current threshold within the determination time.

[0044] The detection device monitors the three-phase current provided by the frequency conversion board for the three-phase motor. It can be imagined that for the monitoring of the three-phase current of the frequency conversion board, the detection device can achieve the monitoring of the three-phase current through the current sampling circuit or current sampling module on it. For example, the current sampling circuit or current sampling module provided in the related technology can be used as long as it can achieve current sampling detection.

[0045] In addition, the three-phase current provided by the variable-frequency board includes phase currents corresponding to three different phases. During the monitoring process, the detection device separately detects each phase current within the determination time to record the number of times the amplitude of each phase current in the three-phase current is greater than the minimum current threshold within the determination time, that is, it records once when the amplitude is greater than the minimum current threshold, and stops counting until the end of the determination time, and takes the recorded number as the corresponding over-limit number. It can be understood that during the actual operation process, the phase current in the same phase will change in the current direction. For example, when the upper transistor is turned on and the lower transistor is turned off, the phase current is in the positive half-cycle and its current direction is the positive direction; while when the lower transistor is turned on and the upper transistor is turned off, the phase current is in the negative half-cycle and its current direction is the negative direction. In this regard, for the phase current corresponding to the positive direction and the phase current corresponding to the negative direction, it is necessary to detect whether their amplitudes are greater than the minimum current threshold and record the corresponding number of times, so as to determine the corresponding over-limit number, that is, it is possible to determine a first over-limit number corresponding to the detection in the positive half-cycle and a second over-limit number corresponding to the detection in the negative half-cycle.

[0046] Step S140: According to the first over-limit number, the second over-limit number, and the phase current amplitude corresponding to each phase current in the three-phase current, perform open-phase detection and damage detection on the variable-frequency board respectively to determine the fault state of the variable-frequency board.

[0047] The fault state of the variable-frequency board includes an open-phase state and a device damage state. For example, when a phase line is missing, it is determined to be in the open-phase state, and when the IGBT is damaged, it is determined to be in the device damage state. For each phase current, the detection device records the corresponding first over-limit number and second over-limit number. During the process of performing open-phase detection on the variable-frequency board, the first over-limit number corresponding to each phase current is compared with a preset number, and the second over-limit number is compared with the preset number, and then it is determined whether the variable-frequency board is open-phase according to the comparison result. Similarly, during the process of detecting whether the IGBT on the variable-frequency board is damaged, the detection device can also judge whether the IGBT is damaged according to the phase current amplitude and determine whether the damaged IGBT is the upper transistor or the lower transistor when damage occurs. In this regard, the detection device specifically determines the fault state of the variable-frequency board by performing open-phase detection and damage detection respectively. It can be imagined that in one embodiment, when the fault state corresponding to the variable-frequency board is the open-phase state, that is, there is a missing phase line in the variable-frequency board. In this case, due to the missing phase line, the detection of whether the IGBT on the variable-frequency board is damaged can no longer be performed, that is, it is only necessary to determine that the fault state is the open-phase state.

[0048] As can be seen from the above solution, this solution selects different determination times and minimum current thresholds according to different control stages of the three-phase motor, and then detects the phase current. By utilizing the characteristics of the phase currents of each phase during the operation of the three-phase motor, through the determination time and minimum current threshold set for different control stages, this solution can accurately and quickly detect the faults occurring in the frequency conversion board, thereby timely detecting the faults of the frequency conversion board, reducing the overcurrent risk, and also helping to reduce the occurrence of misjudgment, improving the accuracy of fault detection.

[0049] In one embodiment, when monitoring the phase current and recording the corresponding overlimit times, the number of times that the positive current in the positive half-cycle of the same phase current is greater than the minimum current threshold is regarded as the first overlimit time, and the number of times that the negative current in the negative half-cycle of the same phase current is greater than the minimum current threshold is regarded as the second overlimit time. It can be imagined that for the positive current and the negative current, since they are provided by the upper tube and the lower tube and are the currents of the phase current within one cycle, when their amplitudes are greater than the minimum current threshold, the detection device records once to determine the corresponding first overlimit time and second overlimit time.

[0050] Furthermore, based on the first overlimit time, the second overlimit time, and the phase current amplitude, the detection device can detect the fault state of the frequency conversion board, such as Figure 5 shown Figure 5 is a schematic diagram of the steps for detecting the fault state of the frequency conversion board provided by an embodiment of the present application. The specific steps include steps S210 - S230:

[0051] Step S210: When the first overlimit time is less than or equal to the preset number of times or the second overlimit time is less than or equal to the preset number of times, it is determined that the frequency conversion board is in a phase loss state, and according to the corresponding phase current, the target phase line missing from the frequency conversion board is determined.

[0052] Step S220: When the frequency conversion board is not in a phase loss state, according to the comparison result between the amplitude of each phase current in the three-phase current and the minimum current threshold, it is determined whether the frequency conversion board is in a device damage state.

[0053] Step S230: When the frequency conversion board is in a device damage state, according to the current direction when the phase current amplitude is less than the minimum current threshold, the target IGBT damaged on the frequency conversion board is determined.

[0054] It can be understood that after obtaining the first overlimit count and the second overlimit count, the detection device compares the first overlimit count with the preset count and the second overlimit count with the preset count respectively. Then, when the first overlimit count (or the second overlimit count) is less than or equal to the preset count, the detection device determines the phase loss state of the variable frequency board. That is, the detection device determines that the number of times the phase current amplitude (the maximum value in the positive half-cycle or negative half-cycle) corresponding to the phase current within the determination time is greater than the minimum current threshold does not exceed the preset count based on the overlimit count. In this regard, the detection device can determine that the variable frequency board is in a phase loss state. Moreover, based on the phase currents corresponding to the first overlimit count and the second overlimit count, the detection device can determine the missing target phase line. For example, if the first overlimit count or the second overlimit count recorded for the phase current corresponding to phase A is less than or equal to the preset count, the detection device can determine that the phase line corresponding to phase A is missing.

[0055] In addition, when it is determined that the variable frequency board is not in a phase loss state, the detection device further compares and judges the amplitudes of each phase current to determine whether the variable frequency board is in a device damage state based on the comparison result. Optionally, in an embodiment, the detection device compares the amplitudes of each phase current (i.e., the above-mentioned phase current amplitudes) with the minimum current threshold respectively. When the amplitude of any phase current is less than the minimum current threshold, the detection device can determine that the variable frequency board is in a device damage state. For example, if the amplitude of the phase current corresponding to phase A is less than the minimum current threshold, it can be determined that the current variable frequency board is in a device damage state; or for another example, when the amplitude of the phase current of phase A in the positive half-cycle is less than the minimum current threshold, in this regard, it can be determined that the IGBT tube acting as the upper tube among the two IGBT tubes corresponding to phase A is damaged.

[0056] By comparing the current amplitudes, the detection device can clearly determine the conditions of the upper tube and the lower tube associated with the phase current, that is, judge whether the upper tube and the lower tube are damaged through the current, so as to improve the accuracy and efficiency of detection.

[0057] Furthermore, when it is determined that the variable frequency board is in a device failure state, the detection device can, during the process of phase current change, associate different IGBTs with the current direction when the phase current amplitude is less than the minimum current threshold. Here, the current direction includes the positive direction and the negative direction. The positive direction is the direction flowing into the three-phase motor, and the negative direction is opposite to the positive direction. For example, for the same phase current, in the positive half-cycle, the current direction is the positive direction, which is associated with the IGBT as the upper transistor; in the negative half-cycle, the current direction is the negative direction, which is associated with the IGBT as the lower transistor. Optionally, in one embodiment, if the current direction is the positive direction, it is determined that the upper transistor of the two IGBTs corresponding to this phase current on the variable frequency board is damaged, that is, the target IGBT is the IGBT as the upper transistor. If the current direction is the negative direction, it is determined that the lower transistor of the two IGBTs corresponding to this phase current on the variable frequency board is damaged, that is, the target IGBT is the IGBT as the lower transistor. It can be imagined that when both the upper transistor and the lower transistor are damaged at the same time, the detection device can determine that both the upper transistor and the lower transistor are the target IGBTs.

[0058] In this regard, the detection device samples the phase current and compares the sampling result with a preset value, and it can accurately detect the fault state of the variable frequency board. That is, by utilizing the characteristics of the phase currents of the three-phase motor during operation, this solution can accurately and quickly detect the faults that occur in the variable frequency board, thereby timely detecting the fault situation of the variable frequency board, which helps to improve the accuracy of fault detection.

[0059] Exemplarily, in the actual application process, when the detection device determines that the three-phase motor is in the open-loop control stage, it determines the minimum current threshold by taking a preset proportion of the starting current. For example, 3 / 4 of the starting current amplitude is selected as the value of the minimum current threshold. Regarding the setting of the determination time for this control stage, this determination time needs to ensure that there is at least one complete current cycle within this time, that is, including a positive half-cycle and a negative half-cycle. Moreover, the more current cycles included in the determination time, the more accurate the detection result can be. Optionally, the determination time can be set to 50 current cycles. In this regard, the detection device records the amplitude of the phase current corresponding to this determination time, such as the maximum value (taking the absolute value) of the phase current within the positive half-cycle and the negative half-cycle, compares it with the minimum current threshold, and records it once when the value is greater than the minimum current threshold, so as to finally statistically obtain the corresponding overlimit times.

[0060] Furthermore, by comparing the number of overlimit times (such as the first overlimit time counted in the positive half-cycle and the second overlimit time counted in the negative half-cycle) with a preset number, for example, if the set preset number is 50, when the first overlimit time is less than or equal to 50 or the second overlimit time is less than or equal to 50, the detection device can determine that the variable-frequency board is in a phase-loss state. If among the three phases A, B, and C, only the first overlimit time detected for the phase current corresponding to phase A meets this condition (i.e., less than or equal to 50), the detection device can determine that the phase line corresponding to phase A in the variable-frequency board is missing. When no phase-loss situation is detected, the detection device can further detect whether the IGBT is damaged, for example, by judging whether the positive current in the phase current exceeds a threshold value and whether the negative current exceeds a minimum current threshold value, that is, detecting whether the phase current has a situation where the amplitude is less than the minimum current threshold value in the positive half-cycle or the negative half-cycle. If it occurs in the positive half-cycle, it is determined that the IGBT of the corresponding upper transistor is the target IGBT to be damaged; if it occurs in the negative half-cycle, it is determined that the IGBT of the corresponding lower transistor is the target IGBT to be damaged.

[0061] In addition, in practical applications, for the closed-loop control stage, the determination time and the minimum current threshold value selected by the detection device are different from those in another control stage. Since in the closed-loop control stage, the three-phase currents of the three-phase motor are related to the speed of the three-phase motor, and the current speed of the three-phase motor is used as the target speed. In this regard, the selected minimum current threshold value can be the minimum phase current of the three-phase motor in the no-load state or the minimum phase current of the three-phase motor in the minimum speed state. And the selected determination time is related to the overshoot recovery time, which corresponds to the duration during which the three-phase motor is lower than the preset speed during the process of reducing from the target speed to the preset speed. Therefore, in some embodiments, the overshoot recovery time can be selected as the determination time. Furthermore, the detection device records the number of times when the phase current amplitude is greater than the minimum current threshold value during this determination time, that is, the corresponding overlimit times are obtained through statistics.

[0062] Similarly, after determining the first over-limit times and the second over-limit times, compare the first over-limit times with the preset times and the second over-limit times with the preset times. For example, the preset times can also be set to 50. When the first over-limit times is less than or equal to 50 or the second over-limit times is less than or equal to 50, the detection device can determine that the frequency conversion board is in a phase loss state. If among the three phases A, B, and C, only the first over-limit times (or the second over-limit times) detected for the phase current corresponding to phase A is less than or equal to 50, the detection device can determine that the phase line corresponding to phase A in the frequency conversion board is missing. When no phase loss situation is detected, the detection device can further detect whether the IGBT is damaged. For example, by detecting whether the phase current has a situation where the amplitude is less than the minimum current threshold in the positive half-cycle or the negative half-cycle, determine the specific damaged IGBT. If it appears in the positive half-cycle, determine that the IGBT corresponding to the upper tube is the damaged target IGBT; if it appears in the negative half-cycle, determine that the IGBT corresponding to the lower tube is the damaged target IGBT.

[0063] Figure 6 FIG. 4 is a schematic structural diagram of a fault detection device provided by an embodiment of the present application. The fault detection device is applied to a detection device, the detection device is connected to a frequency conversion board, the frequency conversion board is used to drive the connected three-phase motor, and the detection device is used to supply power to the frequency conversion board to control the IGBT on the frequency conversion board to provide three-phase current for the three-phase motor. And, the device is used to execute the fault detection method provided by the above embodiment, and has a functional module and beneficial effects for executing the method. As shown in the figure, the device includes a stage detection module 401, a threshold determination module 402, a current monitoring module 403, and a fault judgment module 404.

[0064] Among them, the stage detection module 401 is configured to determine whether the control stage of the three-phase motor belongs to an open-loop control stage or a closed-loop control stage according to the output current provided to the frequency conversion board;

[0065] The threshold determination module 402 is configured to determine the determination time and the minimum current threshold associated with the control stage based on the control stage of the three-phase motor;

[0066] The current monitoring module 403 is configured to monitor the three-phase current on the frequency conversion board, and record the first over-limit times when the amplitude of each phase current in the positive half-cycle is greater than the minimum current threshold and the second over-limit times when the amplitude of each phase current in the negative half-cycle is greater than the minimum current threshold within the determination time;

[0067] The fault judgment module 404 is configured to perform phase loss detection and damage detection on the frequency conversion board respectively according to the first over-limit times, the second over-limit times, and the phase current amplitude corresponding to each phase current in the three-phase current, so as to determine the fault state of the frequency conversion board.

[0068] Based on the above embodiments, when the three-phase motor is in the open-loop control stage, the output current is the starting current, and the starting current is used to drive the three-phase motor to start running from a stationary state. The threshold determination module 402 is specifically configured as follows:

[0069] Calculate the amplitude of the starting current according to a preset ratio to determine the minimum current threshold;

[0070] Use the duration of the starting current maintenance as the upper limit duration of the determination time to set the determination time.

[0071] Based on the above embodiments, the determination time is greater than or equal to one current cycle of the starting current, and one current cycle includes a positive half-cycle and a negative half-cycle.

[0072] Based on the above embodiments, when the three-phase motor is in the closed-loop control stage, the output current is the operating current, and the operating current is used to drive the three-phase motor to operate at a target speed. The threshold determination module 402 is specifically configured as follows:

[0073] Select the minimum phase current of the three-phase motor in the no-load state or the minimum speed state as the minimum current threshold;

[0074] According to the duration during which the three-phase motor is lower than the preset speed during the process of reducing from the target speed to the preset speed, determine the corresponding overshoot recovery time, and use the overshoot recovery time as the lower limit duration to set the determination time.

[0075] Based on the above embodiments, the fault judgment module 404 is specifically configured as follows:

[0076] When the first overlimit number is less than or equal to the preset number or the second overlimit number is less than or equal to the preset number, determine that the frequency conversion board is in the phase loss state, and determine the target phase line missing from the frequency conversion board according to the corresponding phase current;

[0077] When the frequency conversion board is not in the phase loss state, determine whether the frequency conversion board is in the device damage state according to the comparison result of the amplitude of each phase current in the three-phase current with the minimum current threshold;

[0078] When the frequency conversion board is in the device damage state, determine the target IGBT damaged by the frequency conversion board according to the current direction when the phase current amplitude is less than the minimum current threshold.

[0079] Based on the above embodiments, the fault judgment module 404 is further configured as follows:

[0080] Compare the amplitude of each phase current with the minimum current threshold respectively;

[0081] When the amplitude of any phase current is less than the minimum current threshold, determine that the frequency conversion board is in the device damage state.

[0082] Based on the above embodiments, the fault judgment module 404 is further configured to:

[0083] If the current direction is the positive direction, it is determined that the upper transistor of the two IGBTs corresponding to the phase current on the frequency conversion board is damaged, and the positive direction is the direction flowing into the three-phase motor;

[0084] If the current direction is the negative direction, it is determined that the lower transistor of the two IGBTs corresponding to the phase current on the frequency conversion board is damaged, and the negative direction is opposite to the positive direction.

[0085] It should be noted that in the embodiments of the above device, the included modules are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of the modules are only for the convenience of mutual distinction and do not limit the protection scope of the embodiments of the present application.

[0086] Figure 7 It is a schematic structural diagram of a detection device provided by an embodiment of the present application. The device is used to execute the fault detection method provided by the above embodiment, and has functional modules and beneficial effects corresponding to the execution method. As shown in the figure, the detection device includes a processor 501, a memory 502, an input device 503, and an output device 504. The number of processors 501 can be one or more. In the figure, one processor 501 is taken as an example; the processor 501, the memory 502, the input device 503, and the output device 504 can be connected through a bus or other means. In the figure, connection through a bus is taken as an example. The memory 502, as a computer-readable storage medium, can be used to store software programs, computer-executable programs, and modules, such as program instructions / modules corresponding to the fault detection method in the embodiments of the present application. The processor 501 executes corresponding various functional applications and data processing by running the software programs, instructions, and modules stored in the memory 502, that is, implements the above-mentioned fault detection method.

[0087] The memory 502 may mainly include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data recorded or created during use, etc. In addition, the memory 502 may include a high-speed random access memory, and may further include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 502 may further include a memory remotely set relative to the processor 501, and these remotely set memories can be connected to the device through a network. Examples of the above network include but are not limited to the Internet, an enterprise internal network, a local area network, a mobile communication network, and combinations thereof.

[0088] The input device 503 can be used to input corresponding digital or character information to the processor 501, and generate key signal inputs related to the user settings and function controls of the device; the output device 504 can be used to send or display key signal outputs related to the user settings and function controls of the device.

[0089] The embodiment of the present application also provides a storage medium storing computer-executable instructions, and the computer-executable instructions are used to perform related operations in the fault detection method provided by any embodiment of the present application when executed by the processor.

[0090] Computer-readable storage media include permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information accessible by a computing device.

[0091] It should also be noted that the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, commodity or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, commodity or device including the element.

[0092] Note that the above is only the preferred embodiment of the present application and the applied technical principle. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments. Without departing from the concept of the present application, more other equivalent embodiments can be included, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A fault detection method, characterized in that: Applied to a detection device, the detection device is connected to a frequency conversion board, the frequency conversion board is used to drive a connected three-phase motor, the detection device is used to power the frequency conversion board to control the IGBT on the frequency conversion board to provide three-phase current for the three-phase motor, and the fault detection method includes: Determining whether the control stage of the three-phase motor belongs to an open-loop control stage or a closed-loop control stage according to the output current provided to the frequency conversion board; Based on the control stage of the three-phase motor, determining a determination time and a minimum current threshold associated with the control stage; Monitor the three-phase current on the frequency conversion board, and record the first over-limit times during the determination time when the amplitude of each phase current in the three-phase current in the positive half cycle is greater than the minimum current threshold and the second over-limit times during the negative half cycle when the amplitude of each phase current in the three-phase current is greater than the minimum current threshold; According to the first over-limit times, the second over-limit times and the phase current amplitude corresponding to each phase current in the three-phase current, the frequency conversion board is respectively subjected to phase loss detection and damage detection to determine the fault state of the frequency conversion board.

2. The fault detection method according to claim 1, characterized in that: When the three-phase motor is in an open-loop control stage, the output current is a starting current, and the starting current is used to drive the three-phase motor to start running from a stationary state; The determining of the determination time and the minimum current threshold associated with the control stage based on the control stage of the three-phase motor comprises: Calculating the amplitude of the starting current according to a preset ratio to determine the minimum current threshold; The maintenance time of the starting current is used as the upper limit time of the determination time to set the determination time.

3. The fault detection method according to claim 2, characterized in that: The determination time is greater than or equal to a current cycle of the starting current, and one current cycle includes a positive half cycle and a negative half cycle.

4. The fault detection method according to claim 1, characterized in that: In the case that the three-phase motor is in a closed-loop control stage, determining a determination time and a minimum current threshold associated with the control stage based on the control stage of the three-phase motor includes: Selecting the minimum phase current of the three-phase motor in a no-load state or a minimum speed state as the minimum current threshold; According to the time length during which the three-phase motor is lower than the preset speed in the process of decreasing from the target speed to the preset speed, the corresponding overshoot recovery time is determined, and the determination time is set with the overshoot recovery time as the lower limit time length.

5. The fault detection method according to claim 2 or 4, characterized in that: The method of performing phase loss detection and damage detection on the frequency converter board respectively according to the first over-limit times, the second over-limit times and the phase current amplitude corresponding to each phase current in the three-phase current to determine the fault state of the frequency converter board includes: When the first over-limit number is less than or equal to a preset number or the second over-limit number is less than or equal to a preset number, determining that the frequency converter board is in a phase-missing state, and determining the target phase line missing from the frequency converter board according to the corresponding phase current; When the frequency conversion board is not in a phase-loss state, determining whether the frequency conversion board is in a device damage state according to a comparison result between the current amplitude of each phase in the three-phase current and the minimum current threshold; When the frequency converter board is in a device damage state, the target IGBT of the frequency converter board that is damaged is determined according to the current direction when the phase current amplitude is less than the minimum current threshold.

6. The fault detection method according to claim 5, characterized in that: When the frequency conversion board is not in a phase-loss state, determining whether the frequency conversion board is in a device damage state according to a comparison result between the current amplitude of each phase in the three-phase current and the minimum current threshold value includes: Comparing the amplitude of each phase current with the minimum current threshold value respectively; When the amplitude of any phase current is less than the minimum current threshold, it is determined that the frequency conversion board is in a component damage state.

7. The fault detection method according to claim 5, characterized in that: When the frequency converter board is in a device damaged state, determining a target IGBT damaged by the frequency converter board according to a current direction when the phase current amplitude is less than the minimum current threshold value comprises: If the current direction is a positive direction, it is determined that the upper tubes of the two IGBTs corresponding to the phase current on the frequency conversion board are damaged, and the positive direction is the direction of flowing toward the three-phase motor; If the current direction is negative, it is determined that the lower tubes of the two IGBTs corresponding to the phase current on the frequency conversion board are damaged, and the negative direction is opposite to the positive direction.

8. A fault detection device, characterized in that: Applied to a detection device, the detection device is connected to a frequency conversion board, the frequency conversion board is used to drive the connected three-phase motor, the detection device is used to power the frequency conversion board to control the IGBT on the frequency conversion board to provide three-phase current for the three-phase motor, and the fault detection device includes: a stage detection module, configured to determine whether the control stage of the three-phase motor belongs to an open-loop control stage or a closed-loop control stage according to the output current provided to the frequency conversion board; a threshold determination module configured to determine a determination time and a minimum current threshold associated with the control stage based on the control stage of the three-phase motor; a current monitoring module configured to monitor the three-phase current on the frequency conversion board, and record the first over-limit times during the determination time when the amplitude of each phase current in the three-phase current in the positive half cycle is greater than the minimum current threshold and the second over-limit times during the negative half cycle when the amplitude of each phase current in the three-phase current is greater than the minimum current threshold; The fault judgment module is configured to perform phase loss detection and damage detection on the frequency conversion board according to the first over-limit number, the second over-limit number and the phase current amplitude corresponding to each phase current in the three-phase current, so as to determine the fault state of the frequency conversion board.

9. A detection device, characterized in that: include: one or more processors; A storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors implement the fault detection method as described in any one of claims 1-7.

10. A storage medium storing computer executable instructions, characterized in that: The computer executable instructions are used to perform the fault detection method according to any one of claims 1 to 7 when executed by a processor.

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