Method and device for self-checking of a motor drive system

Abstract

The application relates to the motor technical field and provides a self-checking method and a self-checking device of a motor driving system, the method comprising the following steps: controlling two-phase operation of a three-phase full-bridge inverter; synchronously sampling two-phase working currents of the three-phase full-bridge inverter through a current sensor in the first 1 / 4 control period; judging whether the current sensor has a fault according to the two-phase working currents; if it is judged that the current sensor has no fault, calculating the rising rate of the working current; and if the rising rate is greater than a set rising threshold, judging that a motor driven by the motor driving system has an interphase / interturn insulation short-circuit failure fault. The application controls only two-phase bridge arms of the inverter to work, can make the motor realize fault self-checking of the current sensor and interphase / interturn insulation short-circuit failure fault detection of the motor according to the two-phase currents without outputting torque, and can avoid electromagnetic stress of the motor and cause of NVH problems.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and specifically to a self-testing method and a self-testing device for a motor drive system. Background Technology

[0002] Motor drive systems rely on current sensors to detect drive current and achieve closed-loop control of the motor. If the current sensor fails, it will directly lead to uncontrolled motor torque, reduced efficiency, and even system oscillation and malfunctioning overcurrent protection. Furthermore, if phase-to-phase / turn-to-turn insulation occurs in the motor, the resulting huge short-circuit current during operation can directly burn out windings, damage driver power devices, and cause arcing, potentially leading to a fire. In the functional safety design of motor drives, current sensor self-testing and motor insulation short-circuit detection together constitute the guarantee of system safety.

[0003] In related technologies, motor output torque is required for current sensor self-testing and motor insulation short-circuit detection to allow current to flow through the current sensor and motor, and the judgment is based on the current detected by the current sensor. However, the flowing current may cause electromagnetic stress in the motor, leading to NVH (Noise, Vibration, and Harshness) problems. Furthermore, in practical applications, many scenarios have strict controls on unexpected torque output from the motor, making current sensor self-testing and motor insulation short-circuit detection impossible. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the first objective of this invention is to propose a self-testing method and device for a motor drive system, which enables the motor to perform fault self-testing of current sensors and detection of phase-to-phase / turn-to-turn insulation short-circuit failure based on two-phase current without outputting torque, while avoiding electromagnetic stress and NVH problems in the motor.

[0005] The second objective of this invention is to provide a self-testing device for a motor drive system.

[0006] The technical solution adopted in this invention is as follows:

[0007] An embodiment of the first aspect of the present invention provides a self-testing method for a motor drive system. The motor drive system includes a three-phase full-bridge inverter. The method includes the following steps: Step S100, controlling two phase arms of the three-phase full-bridge inverter to operate; Step S200, synchronously sampling the operating current of the two phase arms of the three-phase full-bridge inverter using a current sensor; Step S300, determining whether the current sensor is faulty based on the operating current; Step S400, if the current sensor is determined to be fault-free, calculating the rate of increase of the operating current; Step S500, if the rate of increase is greater than a set threshold, determining that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short-circuit failure fault.

[0008] The self-testing method for the motor drive system proposed above in this invention may also have the following additional technical features:

[0009] According to an embodiment of the present invention, in step S300, determining whether the current sensor is faulty based on the operating current specifically includes: if the sum of the operating currents of the two phase arms is zero, then the current sensor is determined to be in a normal state; if the sum of the operating currents of the two phase arms is not zero, then the current sensor is determined to be in a faulty state.

[0010] According to an embodiment of the present invention, in step S100, controlling two of the bridge arms of the three-phase full-bridge inverter to operate specifically includes: controlling the switches of two of the bridge arms of the three-phase full-bridge inverter to switch synchronously, while the remaining bridge arm remains in the off state.

[0011] According to one embodiment of the present invention, when controlling the switches of two phase arms of the three-phase full-bridge inverter to switch synchronously, the wave emission frequency is greater than 20KHz.

[0012] According to one embodiment of the present invention, in step S400, calculating the rise rate of the operating current specifically includes: obtaining the sampling current and the calibration current of one phase operating current at a set time; and obtaining the rise rate of the operating current based on the calibration current and the difference between the sampling current and the calibration current.

[0013] A second aspect of the present invention provides a self-testing device for a motor drive system, the motor drive system including a three-phase full-bridge inverter, the device comprising: a control module for controlling the operation of two phase arms of the three-phase full-bridge inverter; a sampling module for synchronously sampling the operating current of the two phase arms of the three-phase full-bridge inverter using a current sensor; a first judgment module for determining whether the current sensor is faulty based on the operating current; a calculation module for calculating the rate of rise of the operating current when the current sensor is determined to be fault-free; and a second judgment module for determining that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short-circuit failure fault when the rate of rise is greater than a set rise threshold.

[0014] The self-testing device for the motor drive system proposed in this invention may also have the following additional technical features:

[0015] According to one embodiment of the present invention, the first judgment module is specifically used to: determine that the current sensor is in normal condition if the sum of the operating currents of the two phase bridge arms is zero; and determine that the current sensor is in fault condition if the sum of the operating currents of the two phase bridge arms is not zero.

[0016] According to one embodiment of the present invention, the control module is specifically used to: control the switches of two phase arms of the three-phase full-bridge inverter to switch synchronously, while the remaining phase arm remains in the off state.

[0017] According to one embodiment of the present invention, when the control module controls the switches of two phase arms of the three-phase full-bridge inverter to switch synchronously, the wave emission frequency is greater than 20Hz.

[0018] According to one embodiment of the present invention, the calculation module is specifically used to: obtain the sampling current and the calibration current of one phase operating current at a set time; and obtain the rise rate of the operating current based on the calibration current and the difference between the sampling current and the calibration current.

[0019] The beneficial effects of this invention are:

[0020] This invention controls only two phase bridge arms of the inverter to work, enabling the motor to perform fault self-checking of the current sensor and detection of phase-to-phase / turn-to-turn insulation short-circuit failure faults based on the two-phase current without outputting torque. At the same time, it can avoid electromagnetic stress in the motor and prevent NVH problems. Attached Figure Description

[0021] Figure 1 This is a flowchart of a self-testing method for a motor drive system according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a motor drive system according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the output current variation of an inverter within a complete cycle according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the A-phase current when a motor experiences a phase-to-phase / turn-to-turn insulation short-circuit failure according to an embodiment of the present invention;

[0025] Figure 5 This is a block diagram of a self-testing device for a motor drive system according to an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Figure 1 This is a flowchart of a self-test method for a motor drive system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a motor drive system according to an embodiment of the present invention. Figure 2 As shown, the motor drive system includes a three-phase full-bridge inverter 100, where Vdc represents DC voltage, 200 is the motor, and S1-S6 represent the first to sixth switching transistors.

[0028] like Figure 1 As shown, the self-testing method for a motor drive system includes the following steps:

[0029] S100 controls the operation of two phase arms of the three-phase full-bridge inverter.

[0030] In one embodiment of the present invention, controlling two phase arms of a three-phase full-bridge inverter to operate specifically includes: controlling the switching transistors of two phase arms of the three-phase full-bridge inverter to switch synchronously, while the remaining phase arm remains off.

[0031] Specifically, I A I B and I C To input the actual current of the three phases A, B, and C of the motor, I a I b and I cThis is the sampling current of the input motor's three phases (A, B, and C) detected by the current sensor. It can control the switching transistors of phases A and B to switch synchronously, while the switching transistor of phase C is turned off. For one switching cycle T0, the current change is shown in [reference needed]. Figure 3 As shown, Figure 3 The horizontal axis t represents time, and the vertical axis represents current. The operating sequence of the switching transistors is as follows: at time t0, S1 and S6 are on, and S3 and S4 are off; at time t1, S1 and S6 are off, and S3 and S4 are on; at time t2, S1 and S6 are on, and S3 and S4 are off; at time t3, S1 and S6 are off, and S3 and S4 are on. S2 and S5 remain off at all times.

[0032] Figure 3 This diagram illustrates the output current variation of the inverter over a complete cycle. Within one complete cycle, the current changes due to I... A I B The current vector is formed. The current generated by the switch has the same amplitude and opposite direction between the two phases. In a complete cycle, the motor torque is the instantaneous pulsating torque and the average torque is zero.

[0033] In one embodiment of the present invention, when controlling the switches of two phase arms of a three-phase full-bridge inverter to switch synchronously, the wave emission frequency f0 is greater than 20KHz.

[0034] Specifically, f0 greater than 20kHz exceeds the upper limit of human hearing, which can avoid potential NVH problems. At the same time, the torque pulsation caused by high-frequency current can be fully absorbed by the inertia of the mechanical system, and the motor does not output torque on average.

[0035] The S200 synchronously samples the operating current of two phase arms of the three-phase full-bridge inverter through a current sensor.

[0036] S300 determines whether the current sensor is faulty based on the operating current.

[0037] In one specific embodiment of the present invention, determining whether the current sensor is faulty based on the operating current specifically includes: if the sum of the operating currents of the two phase arms is zero, then the current sensor is determined to be in a normal state; if the sum of the operating currents of the two phase arms is not zero, then the current sensor is determined to be in a faulty state.

[0038] Specifically, according to Figure 3 It can be known that, theoretically, I A +I B =0, therefore, the currents I of phases A and B can be sampled simultaneously. a and I b If the current sensor exhibits the characteristics of equal amplitude and opposite polarity, then it is said that the current sensor is not faulty; otherwise, it indicates that the current sensor may be faulty. In other words, if I...a +I b If I ≠ 0, an anomaly in the current sampling indicates a fault in the current sensor. Considering actual detection error, a certain margin value can be set; if I... a >0 and I b <0, and |I a +I b |>I th1 This can also indicate that the current sensor is faulty. th To set a margin value, the currents I of phases A and B can be sampled synchronously only in the first 1 / 4 cycle. a and I b Perform fault diagnosis on current sensors to avoid excessive data collection that consumes unnecessary resources.

[0039] Similarly, by controlling the switching transistors of phase A and phase C bridge arms to switch synchronously and the switching transistor of phase B bridge arm to turn off, the current sensor can also be self-tested based on the current combination of Ia and Ic.

[0040] Similarly, the switching transistors controlling phase B and phase C bridge arms are switched synchronously, while the switching transistor for phase A bridge arm is turned off, according to I... b The current combination with IC can also enable the current sensor to perform self-testing.

[0041] S400: If it is determined that the current sensor is not faulty, the rise rate of the operating current is calculated.

[0042] S500 If the rate of increase is greater than the set rate of increase threshold, it is determined that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short circuit failure fault.

[0043] Specifically, such as Figure 4 As shown, the rate of rise of the current in the t0-t1 interval is determined by the open-circuit voltage Volc and the motor inductance L. AB and motor stator resistance R AB Given a specific initial state, all three parameters mentioned above are definite and can be calibrated. Therefore, the A-phase current I at time Ts is... A It can be calculated / calibrated if it is determined that the current sensor is not faulty, and the actual sampling current Ia-Ia of phase A is... A >I th2 I th2 To determine if the motor has experienced a phase-to-phase / turn-to-turn insulation short-circuit failure, a threshold value can be set to indicate that the motor has failed. This is because after insulation failure, L... AB This will decrease, leading to an increase in the rate of current rise. Of course, L AB Because the current becomes extremely small after a short circuit, the expected current at time t1 may be extremely large, which may trigger an overcurrent fault in the system and detect system abnormalities.

[0044] It should be noted that the synchronous switch must be in its initial state, and the initial current of each phase of the motor must be zero.

[0045] In summary, the self-testing method for the motor drive system according to embodiments of the present invention controls two phases of a three-phase full-bridge inverter to operate; synchronously samples the two-phase operating current of the three-phase full-bridge inverter using current sensors; determines whether the current sensor is faulty based on the two-phase operating current; if the current sensor is determined to be fault-free, calculates the rate of increase of the operating current; if the rate of increase is greater than a set threshold, determines that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short-circuit failure fault. Therefore, by controlling only two phases of the inverter to operate, the motor can perform fault self-testing of the current sensor and detection of phase-to-phase / turn-to-turn insulation short-circuit failure faults based on the two-phase current without outputting torque, while simultaneously avoiding electromagnetic stress and NVH problems in the motor.

[0046] Corresponding to the self-testing method for the motor drive system described above, this invention also proposes a self-testing device for the motor drive system. For details not disclosed in the device embodiments, please refer to the method embodiments described above; they will not be repeated here.

[0047] Figure 5 This is a block diagram of a self-testing device for a motor drive system according to an embodiment of the present invention. The motor drive system includes a three-phase full-bridge inverter, such as... Figure 5 As shown, the device includes: a control module, a sampling module, a first judgment module, a calculation module, and a second judgment module.

[0048] The control module controls the operation of two phase arms of the three-phase full-bridge inverter; the sampling module synchronously samples the operating current of two phase arms of the three-phase full-bridge inverter using a current sensor; the first judgment module determines whether the current sensor is faulty based on the operating current; the calculation module calculates the rate of rise of the operating current when the current sensor is determined to be fault-free; and the second judgment module determines that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short-circuit failure fault when the rate of rise is greater than a set rise threshold.

[0049] According to one embodiment of the present invention, the first judgment module is specifically used to: determine that the current sensor is in normal condition if the sum of the operating currents of the two phase arms is zero; and determine that the current sensor is in fault condition if the sum of the operating currents of the two phase arms is not zero.

[0050] According to one embodiment of the present invention, the control module is specifically used to: control the switches of two phase arms of the three-phase full-bridge inverter to switch synchronously, while the remaining phase arm remains in the off state.

[0051] According to one embodiment of the present invention, when the control module controls the switches of two phase arms of the three-phase full-bridge inverter to switch synchronously, the wave emission frequency is greater than 20KHz.

[0052] According to one embodiment of the present invention, the calculation module is specifically used to: obtain the sampling current and the calibration current of one phase operating current at a set time; and obtain the rate of rise of the operating current based on the difference between the calibration current and the sampling current and the calibration current.

[0053] In summary, the self-testing device for the motor drive system according to an embodiment of the present invention controls two phase arms of the three-phase full-bridge inverter to operate via a control module. During the first quarter of the control cycle, a sampling module synchronously samples the operating current of the two phase arms of the three-phase full-bridge inverter via a current sensor. A first judgment module determines whether the current sensor is faulty based on the operating current. When the calculation module determines that the current sensor is not faulty, it calculates the rate of rise of the operating current. A second judgment module determines that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short-circuit failure fault when the rate of rise exceeds a set threshold. Therefore, by controlling only two phase arms of the inverter to operate, the motor can perform fault self-testing of the current sensor and detection of phase-to-phase / turn-to-turn insulation short-circuit failure faults based on the two-phase current without outputting torque. This also avoids electromagnetic stress on the motor and prevents NVH problems.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of the invention pertain.

[0057] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0058] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any of the following techniques known in the art, or a combination thereof: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0059] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware, and the program can be stored in a computer-readable storage medium. When executed, the program includes one or a combination of the steps of the method embodiments.

[0060] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A self-testing method for a motor drive system, characterized in that, The motor drive system includes a three-phase full-bridge inverter, and the method includes the following steps: Step S100: Control two of the bridge arms of the three-phase full-bridge inverter to operate; Step S200: The operating current of two phase arms of the three-phase full-bridge inverter is synchronously sampled using a current sensor; Step S300: Determine whether the current sensor is faulty based on the operating current; Step S400: If it is determined that the current sensor is not faulty, then calculate the rate of rise of the operating current; Step S500: If the rate of increase is greater than the set rate of increase threshold, it is determined that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short circuit failure fault.

2. The self-testing method for a motor drive system according to claim 1, characterized in that, In step S300, determining whether the current sensor is faulty based on the operating current specifically includes: If the sum of the operating currents of the two phase arms is zero, then the current sensor is considered to be in normal condition. If the sum of the operating currents of the two phase arms is not zero, the current sensor is determined to be in a fault state.

3. The self-testing method for a motor drive system according to claim 1, characterized in that, In step S100, controlling two phase arms of the three-phase full-bridge inverter to operate specifically includes: The switching transistors of two phase arms of the three-phase full-bridge inverter are controlled to switch synchronously, while the remaining phase arm remains off.

4. The self-testing method for a motor drive system according to claim 3, characterized in that, When controlling the synchronous switching of two phase arms of the three-phase full-bridge inverter, the wave frequency is greater than 20KHz.

5. The self-testing method for a motor drive system according to claim 1, characterized in that, In step S400, the rate of rise of the operating current is calculated, specifically including: Obtain the sampling current and calibration current of one phase operating current at a set time; The rate of rise of the operating current is obtained based on the calibration current and the difference between the sampled current and the calibration current.

6. A self-testing device for a motor drive system, characterized in that, The motor drive system includes a three-phase full-bridge inverter, and the device includes: The control module is used to control the operation of two phase arms of the three-phase full-bridge inverter. A sampling module is used to synchronously sample the operating current of two phase arms of the three-phase full-bridge inverter via a current sensor. The first judgment module is used to determine whether the current sensor is faulty based on the operating current. A calculation module is used to calculate the rate of rise of the operating current when it is determined that the current sensor is not faulty; The second judgment module is used to determine that the motor driven by the motor drive system has a phase-to-phase / turn-to-turn insulation short circuit failure when the rise rate is greater than a set rise threshold.

7. The self-testing device for the motor drive system according to claim 6, characterized in that, The first judgment module is specifically used for: If the sum of the operating currents of the two phase arms is zero, then the current sensor is considered to be in normal condition. If the sum of the operating currents of the two phase arms is not zero, the current sensor is determined to be in a fault state.

8. The self-testing device for the motor drive system according to claim 6, characterized in that, The control module is specifically used for: The switching transistors of two phase arms of the three-phase full-bridge inverter are controlled to switch synchronously, while the remaining phase arm remains off.

9. The self-testing device for the motor drive system according to claim 8, characterized in that, When the control module controls the synchronous switching of two phase arms of the three-phase full-bridge inverter, the wave emission frequency is greater than 20KHz.

10. The self-testing device for the motor drive system according to claim 6, characterized in that, The calculation module is specifically used for: Obtain the sampling current and calibration current of one phase operating current at a set time; The rate of rise of the operating current is obtained based on the calibration current and the difference between the sampled current and the calibration current.

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