Active short circuit control method and device for permanent magnet synchronous motor, and medium

Abstract

The invention relates to an active short-circuit control method and device for a permanent magnet synchronous motor, and a medium. The method comprises the steps: collecting an analog signal of a permanent magnet synchronous motor driving system; estimating a back electromotive force deviation signal using a back electromotive force deviation observer based on the analog quantity; judging whether the turn-to-turn short circuit fault characteristic exceeds a preset threshold value or not based on the back electromotive force deviation signal; if so, identifying the fault as a turn-to-turn short circuit fault, otherwise, judging whether inversion overcurrent or inversion module fault exists or not; based on the identified short-circuit fault type, diagnosing a short-circuit occurrence position; according to the short circuit occurrence position, active short circuit control is executed, and after the active short circuit control is executed, turn-to-turn short circuit fault re-diagnosis is carried out to confirm whether the fault exists or not. The turn-to-turn short circuit is accurately identified through the back electromotive force deviation observer, and fault position diagnosis and flexible active short circuit control are combined, so that the transient current impact is remarkably reduced while the system safety is guaranteed, and the continuous operation capability of the system after the fault is effectively maintained.

Description

Technical Field

[0001] This invention relates to the field of electrical systems, specifically to a method, device, and medium for active short-circuit control of a permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in fields with extremely high reliability requirements, such as new energy vehicles, home appliances, aerospace, and medical devices, due to their advantages of high power density, high efficiency, and excellent control performance. However, permanent magnets continue to generate back electromotive force (EMF) even after the motor is powered off. This characteristic means that in the event of a short-circuit fault, the fault current cannot be automatically shut off, potentially leading to a continuous short-circuit current that can cause serious damage to critical components such as the motor and inverter, and even jeopardize the safe operation of the entire system.

[0003] In applications such as rail transit where immediate shutdown is not permissible, high-speed trains must maintain continuous operation even after individual traction motors fail (i.e., "fault-through" or "fault-degraded operation" capability). Therefore, rapid and accurate fault identification and reliable safety protection of the motor drive system are crucial to ensuring the safety of personnel and equipment.

[0004] Currently, traditional short-circuit protection strategies for permanent magnet synchronous motors mainly rely on hardware protection (such as fast-acting fuses) and simple software protection (such as overcurrent blocking inverter pulses). While these methods are simple and direct, they have significant limitations: Traditional overcurrent protection typically operates only when the current has reached a dangerous level, making it a "passive" protection system with an insufficiently timely response. Furthermore, it often struggles to accurately distinguish fault types (such as inter-turn short circuits or phase-to-phase short circuits) and pinpoint the location of the fault (such as inside the motor, in the inverter bridge arm, or on the DC side).

[0005] Once a fault is detected, traditional strategies often employ a "hard" protection method that immediately blocks the drive signal and cuts off the power supply. While this method isolates the fault, it also directly leads to a power interruption, failing to meet the application requirements mentioned above that necessitate continuous operation after a fault.

[0006] When performing active short-circuit control (such as three-phase short circuit) to consume back EMF, if the control timing is inappropriate (such as directly short-circuiting at any point of current or voltage), huge transient current surges and electromagnetic torque pulsations will be generated, which may cause secondary damage to the transmission system and power devices.

[0007] For early-stage inter-turn short-circuit faults, the fault characteristics are very weak and easily masked by system noise and fluctuations in normal operating conditions. Existing methods mostly rely on single characteristic quantities (such as negative sequence current and current harmonics) for diagnosis, which can easily lead to misjudgment or missed judgment under complex and variable application conditions, resulting in unnecessary downtime or failure to provide timely warnings.

[0008] Therefore, there is an urgent need in this field for a strategy and system that can achieve rapid and accurate fault identification and location, and on this basis, execute smooth and reliable active safety control, so as to maximize the maintenance of the driving system's operational capability while ensuring system safety. Summary of the Invention

[0009] This invention provides an active short-circuit control method, device, and medium for permanent magnet synchronous motors. Its purpose is to solve the problems of poor system safety and power interruption caused by the slow response, inaccurate diagnosis, and coarse control of traditional protection methods when a short-circuit fault occurs in the permanent magnet synchronous motor drive system. By achieving accurate fault identification and location and flexible active short-circuit control, the system can maintain its continuous operation capability to the maximum extent while ensuring safety.

[0010] To achieve the above objectives, the first aspect of the present invention provides an active short-circuit control method for a permanent magnet synchronous motor, comprising the following steps: Acquire analog signals from the permanent magnet synchronous motor drive system; Based on the analog quantity, the back potential deviation signal is estimated using a back potential deviation observer. Based on the back EMF deviation signal, determine whether the inter-turn short circuit fault characteristics exceed a preset threshold; if they exceed the threshold, they are identified as an inter-turn short circuit fault; otherwise, determine whether there is inverter overcurrent or inverter module fault. Based on the identified short-circuit fault type, the location of the short circuit is diagnosed; Based on the diagnosed location of the short circuit, active short circuit control is implemented, including adjusting the three-phase output voltage to gradually decrease to zero for inter-turn short circuits inside the motor; and turning on the upper or lower three-phase transistors of the inverter at a set position for inter-phase short circuits. After identifying an inter-turn short-circuit fault and implementing active short-circuit control, an inter-turn short-circuit fault re-diagnosis is performed to finally confirm whether the fault exists.

[0011] Furthermore, based on the analog quantity, the method for estimating the back potential deviation signal using a back potential deviation observer includes: Set the position angle of the resolver rotor; The reference back EMF deviation signal is calibrated offline using a normal motor under different voltages, speeds, and torques. The resolver rotor position angle and the reference back EMF deviation signal are input to the back EMF deviation observer, and the back EMF deviation signal is estimated based on the output of the back EMF deviation observer.

[0012] Furthermore, methods for determining whether the characteristics of inter-turn short-circuit faults exceed a preset threshold include: The amplitude of the estimated back EMF deviation signal is calculated as a fault characteristic quantity; Determine whether the fault characteristic quantity exceeds a preset judgment threshold; If the value exceeds the limit, an inter-turn short circuit fault is determined; otherwise, an inverter overcurrent or inverter module fault is determined.

[0013] Furthermore, methods for re-diagnosing inter-turn short-circuit faults include: Determine whether the permanent magnet synchronous motor is in a three-phase active short-circuit steady state; If a steady state is reached, the pre-stored reference electrical parameters, which were calibrated offline by a normal motor, are retrieved based on the current motor speed and rotor position. The amplitude and phase of the line voltage and phase current collected in real time are compared with the reference electrical parameters obtained in the query. An evaluation function is constructed based on the comparison results, and the existence of an inter-turn short circuit fault is finally confirmed based on the output of the evaluation function. The evaluation function is constructed using a weighted sum of squares method, and its calculation formula is as follows:

[0014] in, For the evaluation function, ~ These are the weighting coefficients. Indicates amplitude. Indicates phase, and These are the real-time sampled line voltage amplitude and line voltage phase, respectively. and These are the baseline voltage amplitude and phase, respectively, retrieved from a pre-stored table. The baseline voltage amplitude and phase are obtained through offline calibration of a normal motor. and These are the phase current amplitude and phase current phase sampled in real time, respectively. and These are the reference phase current amplitude and reference phase current phase obtained from a pre-stored table, respectively. The reference phase current amplitude and phase are obtained by a normal motor under offline calibration conditions.

[0015] Furthermore, based on the identified short-circuit fault type, methods for diagnosing the location of the short circuit include: If the fault is identified as an inter-turn short circuit fault inside the motor, the location of the short circuit is diagnosed as inside the permanent magnet synchronous motor. If an inverter overcurrent or inverter module fault is detected, the following diagnostic procedure will be executed: a) Control the disconnection of the isolation contactor to isolate the permanent magnet synchronous motor from the DC side of the inverter; b) After disconnection, if the current sensor reading is close to zero and the motor line voltage is normal, the short circuit location is diagnosed as the DC side of the inverter. c) If the collected three-phase currents show a phase-to-phase short-circuit characteristic current and the motor line voltage is abnormal, the short circuit location is diagnosed as the inverter bridge arm. d) If the current sensor reading is close to zero and the motor line voltage is abnormal, the short circuit location is diagnosed as the three-phase terminals of the motor.

[0016] Furthermore, based on the diagnosed location of the short circuit, the methods for implementing active short-circuit control include: If the location of the short circuit is diagnosed as an internal inter-turn short circuit in the motor, the control isolation contactor will remain closed, and the three-phase output voltage of the inverter will gradually decay to zero within a set time. If the location of the short circuit is diagnosed as a short circuit on the DC side of the inverter, the inverter's pulse signal will be immediately blocked and the isolation contactor will be disconnected. If the short circuit location is diagnosed as a short circuit in the inverter bridge arm or a short circuit in the three-phase terminals of the motor, the control isolation contactor is kept closed. Then, the electrical characteristics of the motor line voltage or stator current are identified, and when the electrical characteristics reach a preset predetermined position, the three-phase upper or lower transistors of the inverter are simultaneously turned on.

[0017] Furthermore, methods for gradually decaying the three-phase output voltage of the inverter to zero within a set time include: Determine if the motor's rotary transformer is faulty; If the rotary transformer fails, the motor control system will be switched to a sensorless control mode. The two orthogonal components of the inverter's current output voltage vector in the synchronous rotating coordinate system at the switching moment are used as initial values; Within a first set time period, the phase of the output voltage vector is adjusted so that one of its orthogonal components is linearly reduced to zero, while the amplitude of the output voltage vector remains unchanged. After the orthogonal component is reduced to zero, another orthogonal component is linearly reduced to zero within a second set time period.

[0018] Furthermore, when the electrical characteristic reaches a preset predetermined position, the simultaneous conduction of either the three-phase upper transistor or the three-phase lower transistor of the inverter is achieved through any of the following methods: The motor line voltage is collected, and a conduction operation is performed when any phase line voltage reaches its peak value or zero crossing point; or, the motor stator current is collected, and a conduction operation is performed when the stator current amplitude reaches its peak value.

[0019] Furthermore, the permanent magnet synchronous motor is a three-phase, five-phase, six-phase, double three-phase, or open-winding permanent magnet synchronous motor.

[0020] To achieve the above objectives, a second aspect of the present invention provides an electronic device, including a memory and a processor, characterized in that the memory is used to store a program that supports the processor in executing the active short-circuit control method for a permanent magnet synchronous motor, and the processor is configured to execute the program stored in the memory.

[0021] To achieve the above objectives, a third aspect of the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, performs the steps of the active short-circuit control method for a permanent magnet synchronous motor.

[0022] The beneficial effects of this invention are: Compared with existing technologies, the present invention provides an active short-circuit control method for permanent magnet synchronous motors. In the fault identification stage, by employing a back-EMF deviation observer to perform deep state reconstruction and feature fusion on the collected analog signals such as voltage and current, it effectively extracts and amplifies weak inter-turn short-circuit features that are difficult to capture using traditional methods. This overcomes the deficiency of insufficient diagnostic reliability due to reliance on a single fault feature, achieving sensitive detection of early inter-turn short-circuit faults. Furthermore, by introducing an inter-turn short-circuit fault re-diagnosis mechanism, after the system enters steady state following active short-circuit control, a refined comparison of real-time electrical parameters with pre-stored normal motor reference parameters is performed to re-verify the initial diagnostic results. This effectively avoids misjudgments caused by instantaneous interference or operating condition fluctuations, greatly improving the diagnostic accuracy and system decision reliability. Secondly, in the fault location stage, by combining the inverter overcurrent signal with the combined judgment of current sensor readings and line voltage status after actively disconnecting the isolation contactor, a systematic diagnostic process is established, capable of accurately distinguishing fault occurrences. The faults can originate in various locations, such as inside the motor, on the inverter bridge arm, or on the DC side, solving the problem of ambiguous fault location judgment in traditional methods. Finally, in the safety control phase, the simple blocking of pulses or crude short circuits are completely abandoned. A flexible active short circuit strategy that precisely matches the fault type and location is implemented. For inter-turn short circuits inside the motor, a "soft landing" method is adopted to gradually decay the output voltage vector to zero in two stages while maintaining a stable amplitude. For external phase-to-phase short circuits, the three-phase bridge arm is synchronously turned on at the optimal electrical phase point, such as the current peak or voltage zero crossing, through real-time monitoring. This achieves a smooth and low-impact transition from the fault state to the three-phase short-circuit steady state. This method, combined with the aforementioned re-diagnosis mechanism, forms a complete closed loop of "preliminary diagnosis - safety control - final confirmation". While quickly ensuring system safety (consuming back EMF and limiting fault development), it suppresses transient current and torque impacts to the maximum extent, protects hardware equipment, and provides a decision basis for the system to resume operation after eliminating false alarms. This significantly enhances the system's fault tolerance and continuous operation capability. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0024] Figure 1 This is a circuit diagram of the active safety control system for a permanent magnet synchronous motor disclosed in an embodiment of the present invention.

[0025] Figure 2 This is a flowchart of the active short-circuit control strategy for permanent magnet synchronous motors disclosed in an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0027] According to embodiments of the present invention, it should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the following manufacturing method, in some cases the steps shown or described may be performed in a different order than that shown here.

[0028] Figure 1 The hardware configuration of the active safety control system for the applied permanent magnet synchronous motor (PMSM) consists of five main parts: an inverter, an isolation contactor, current sensors, voltage sensors, and the PMSM itself. The inverter's DC side is connected to a DC power supply (such as a battery or bus capacitor), and its AC output is connected to the three-phase input of the PMSM via three-phase wires. An isolation contactor is connected in series between the inverter's DC side and the DC power supply to ensure safe isolation of the high-voltage circuit in case of a fault. Current sensors detect the phase current flowing into the PMSM; their installation location can be anywhere on the circuit between the inverter's output side and the PMSM. Voltage sensors detect the line voltage at the PMSM terminals; their installation location is also not strictly limited and can be located at the PMSM's three-phase input. Each sensor is signal-connected to a control unit (such as a microprocessor), transmitting the collected analog signals to the control unit for processing. The control unit then generates drive signals for the inverter's power switches and the isolation contactor.

[0029] like Figure 2 As shown, the present invention provides an active short-circuit control method for a permanent magnet synchronous motor, comprising the following steps: Step S100: Acquire analog signals from the permanent magnet synchronous motor drive system; The signals collected in this step serve two main purposes: first, for normal vector control calculations of the motor; and second, specifically for the diagnosis and location of short-circuit faults.

[0030] Specifically, to achieve basic motor control, it is necessary to collect DC bus voltage, motor speed and rotor position signals detected by a rotary transformer or encoder, and motor phase current measured by a current sensor.

[0031] Simultaneously, to implement the fault diagnosis and safety control strategy of this invention, specific signals for diagnosis also need to be collected, including the isolation contactor status feedback signal used to determine the on / off state of the main circuit, the three-phase line voltage at the motor terminals measured in real time by a voltage sensor, and the aforementioned motor phase current signal. These voltage and current signals contain information about the system's operating status, and when various short-circuit faults occur, their amplitude, phase, and waveform will exhibit characteristics different from the normal state.

[0032] Step S200: Based on the analog quantity, estimate the back EMF deviation signal using the back EMF deviation observer; To overcome the limitations of single characteristics such as negative sequence current, third harmonic of current, and second harmonic of instantaneous power in diagnosis, this invention designs a back EMF deviation observer for inter-turn short circuit diagnosis. The observer fuses and amplifies the weak inter-turn short circuit characteristics in the motor simulation signal to obtain the estimated back EMF deviation signal.

[0033] In practical implementation, the back EMF deviation observer is a state observer constructed based on a mathematical model of a permanent magnet synchronous motor. Its estimation model can be expressed as:

[0034] in, This indicates that the stator voltage vector of a permanent magnet synchronous motor is at rest. Orthogonal components in a coordinate system; This indicates that the stator voltage vector of a permanent magnet synchronous motor is at rest. Orthogonal components in a coordinate system; This indicates that the stator current vector of a permanent magnet synchronous motor is at rest. Orthogonal components in a coordinate system; This indicates that the stator current vector of a permanent magnet synchronous motor is at rest. Orthogonal components in a coordinate system; For stator resistance, and For right- and quadrature-axis inductors, For differential operators, Electric angular velocity, The electrical angle is calculated from the resolver signal. The magnetic flux linkage is a permanent magnet. The output of the back potential deviation observer is the back potential deviation signal. and .

[0035] To ensure that the back EMF deviation signal output by the back EMF deviation observer is close to zero when the motor is operating normally, thus highlighting the anomaly during a fault, it is necessary to adjust the permanent magnet flux linkage. Precise calibration is required. Considering the nonlinear coupling characteristics of motor parameters, a normal (fault-free) motor must be used in practice, and offline calibration must be performed across its entire operating range (i.e., under different DC voltage, speed, and torque conditions) to determine whether it can be used effectively. and Fluctuating around zero The value is then pre-stored into the controller's program.

[0036] Understandably, during the online operation phase, the controller will collect real-time data on motor phase current, line voltage, and resolver rotor position angle. and the calibrated The parameters are input together into the constructed back potential deviation observer. This observer performs real-time calculations using an algorithm and ultimately outputs the estimated back potential deviation signal. and .

[0037] Step S300: Based on the back EMF deviation signal, determine whether the inter-turn short circuit fault characteristics exceed a preset threshold; if they exceed the threshold, identify it as an inter-turn short circuit fault; otherwise, determine whether there is inverter overcurrent or inverter module fault. After successfully estimating the back EMF deviation signal, it is necessary to extract fault characteristic quantities that can be used for quantitative judgment from the estimated back EMF deviation signal. These fault characteristic quantities are defined as the back EMF deviation signal. and The formula for calculating the composite amplitude is: This amplitude characteristic can comprehensively reflect the overall degree of anomaly in the two-phase deviation signal, effectively avoiding misjudgments that may be caused by signal fluctuations in one direction.

[0038] The calculated fault characteristic amplitude is compared with a preset judgment threshold. This threshold is statistically derived from a large amount of experimental data under normal and fault conditions and is embedded in the controller program. To improve the reliability of the diagnosis and prevent false alarms caused by transient interference, this implementation sets a time condition: the control unit only determines that an inter-turn short circuit fault has occurred inside the permanent magnet synchronous motor and triggers the corresponding fault flag when the fault characteristic amplitude continuously exceeds the preset threshold for a predetermined time length.

[0039] If the fault characteristic quantity does not exceed the threshold, or the duration of the exceedance is insufficient, it indicates that there are currently no obvious inter-turn short-circuit fault characteristics. At this time, the control flow will switch to checking other potential faults in the drive system. The controller will determine whether there is inverter overcurrent (meaning the instantaneous value of the phase current exceeds the hardware protection threshold) or inverter module fault reported by the inverter's own diagnostic circuit. If these inverter-related faults exist, the flow will proceed to the next step of short-circuit location diagnosis; if not, the system considers there to be no urgent short-circuit fault, and the control flow will return to step S100 to continue the cyclic monitoring.

[0040] Step S400: Based on the identified short circuit fault type, diagnose the location of the short circuit; If the short circuit fault was identified as an internal inter-turn short circuit in the previous step (S300), the short circuit location is directly diagnosed as inside the permanent magnet synchronous motor. In this case, no additional location diagnosis logic is required, and the process can directly enter the flexible active short circuit control flow for internal motor faults.

[0041] If the previous step indicates an inverter overcurrent or inverter module fault, a systematic diagnostic process is required to locate the short circuit. First, the control unit immediately issues a command to disconnect the isolation contactor on the DC side of the inverter. This operation aims to electrically isolate the permanent magnet synchronous motor (and its load side) from the inverter's DC power supply, thereby creating an observable diagnostic window.

[0042] After the isolating contactor reliably disconnects, the control system continues to monitor and make judgments, using the combination of feedback signals from the current and voltage sensors to pinpoint the location: Diagnosing short circuit point A (inverter DC side short circuit): If, after disconnecting the contactor, the current sensor reading drops rapidly and remains close to zero, while the motor line voltage shows no obvious abnormalities (e.g., the back EMF voltage generated by its inertial rotation is within the normal range), then the short circuit is determined to occur in the isolated area, i.e., the inverter DC side.

[0043] Diagnosing short circuit point B (inverter bridge arm short circuit): If, after disconnecting the contactor, a significant phase-to-phase short circuit characteristic current (such as two phase currents being approximately the same in magnitude but opposite in direction) is detected in the collected three-phase current, and the motor line voltage exhibits abnormal fluctuations or distortions, then the short circuit is determined to occur on the inverter power bridge arm, i.e., the inverter bridge arm.

[0044] Diagnosing short circuit point C (short circuit at the three-phase terminals of the motor): If, after disconnecting the contactor, the current sensor reading is close to zero, but the motor line voltage is abnormal (for example, due to a sudden change in the internal magnetic field of the motor or a severe distortion of the back EMF waveform caused by an external short circuit), then the short circuit is determined to occur at the external terminals of the motor, i.e., the three-phase terminals of the motor.

[0045] By combining sensor signals based on changes in contactor state, this invention can clearly distinguish and locate three different phase-to-phase short circuit locations, achieving a precise closed loop from fault type identification to fault location.

[0046] Step S500: Based on the diagnosed short circuit location, perform active short circuit control, including adjusting the three-phase output voltage to gradually decrease to zero for inter-turn short circuits inside the motor; and turning on the upper or lower three-phase inverter at a set position for phase-to-phase short circuits.

[0047] If the short circuit is diagnosed as an internal inter-turn short circuit within the motor, the control system will employ a "flexible active short circuit" strategy. First, the isolation contactor is kept closed to maintain the system configuration. Then, the inverter's three-phase output voltage is gradually decayed to zero within a set time.

[0048] It should be noted that in the vector control of permanent magnet synchronous motors, a dq coordinate system that rotates synchronously with the rotor is introduced to control AC motors as efficiently as DC motors. The d-axis (direct axis) is defined as having its positive direction always aligned with the principal direction of the rotor's permanent magnet magnetic field. Controlling the d-axis current is primarily used to adjust the strength of the motor's magnetic field (i.e., "magnetizing" or "demagnetizing"). The q-axis (quadrature axis) is spatially perpendicular (or orthogonal) to the d-axis. Controlling the q-axis current directly determines the electromagnetic torque generated by the motor and is the main driver of its rotation. This decomposition simplifies the control of a complex AC motor to the control of two independent DC components, thereby achieving high-precision torque and speed regulation.

[0049] In practice, the first step is to determine if the motor's rotary transformer is functioning correctly. If the rotary transformer is faulty, the control system must be switched to a sensorless mode to ensure continuous control. Then, the d-axis voltage component of the inverter's current output voltage vector at the switching moment in the synchronous rotating coordinate system is used as the reference. and q-axis voltage component As the initial value. At the first set time. Internally, by adjusting the phase of the voltage vector, the q-axis voltage component is... The voltage is linearly reduced to zero while maintaining the magnitude of the voltage vector, thus smoothly eliminating the torque current component. After dropping to zero, at the second set time Inside, the d-axis voltage component is then... The current is linearly reduced to zero, eventually bringing the motor into an open-circuit state with no voltage output, achieving a smooth current transition and minimizing electromagnetic torque and current surges.

[0050] If the short circuit is diagnosed as occurring on the DC side of the inverter (short circuit point A), it indicates that the fault lies between the isolation contactor and the inverter. In this case, the safest and most effective strategy is to perform complete electrical isolation. Therefore, the control system will immediately block all pulse signals from the inverter, cut off its switching action, and control the disconnection of the isolation contactor, thereby completely disconnecting the faulty DC side from the power supply and the motor.

[0051] If the short circuit is diagnosed as occurring at either the inverter bridge arm (short circuit point B) or the three-phase terminals of the motor (short circuit point C), then "three-phase active short circuit" control is required. In this case, the isolating contactor also needs to be kept closed to ensure a current path is established. Subsequently, the system does not act immediately but first identifies the electrical characteristics of the motor line voltage or stator current and waits for an optimal conduction timing.

[0052] This invention provides two optional triggering methods: Method 1 involves real-time acquisition of motor line voltage; when any phase line voltage reaches its positive or negative peak value, or passes through a zero-crossing point, the three-phase upper transistors (or three-phase lower transistors) of the inverter are simultaneously turned on. Method 2 involves real-time acquisition of motor stator current; when the calculated composite vector amplitude of the stator current reaches its peak value, the same turn-on operation is performed. Choosing to switch at these specific electrical positions utilizes the system's natural periodicity, allowing the system to transition as smoothly as possible from an asymmetrical short-circuit state to a symmetrical three-phase short-circuit steady state, thereby minimizing transient current surges and protecting power devices and the mechanical transmission system.

[0053] Step S600: After identifying an inter-turn short circuit fault and executing active short circuit control, perform a re-diagnosis of the inter-turn short circuit fault to finally confirm whether the fault exists.

[0054] After identifying an inter-turn short-circuit fault and implementing corresponding active short-circuit control (such as flexible active short-circuit), to further improve the reliability of the diagnosis and avoid unnecessary system performance loss or power interruption due to misjudgment, this invention also designs an inter-turn short-circuit fault re-diagnosis step. This step is started asynchronously after the active short-circuit control is executed, aiming to utilize the electrical characteristics of the system after entering a new steady state for secondary verification.

[0055] The first step in the re-examination process is to determine whether the permanent magnet synchronous motor has entered a three-phase active short-circuit steady state. The control system monitors the three-phase current. When the current fluctuation amplitude is detected to be stable within a preset small range and its periodicity reaches a stable state, it is determined that the system has reached the steady-state conditions for re-examination.

[0056] After confirming that the system has reached steady state, the control system will look up a table of reference electrical parameters pre-stored in the controller's non-volatile memory based on the current motor speed and rotor position. This table is obtained through offline calibration of a normal (fault-free) motor before it leaves the factory or is installed in the vehicle.

[0057] The calibration process requires placing the normal motor under a three-phase active short-circuit state. Within its entire operating speed range, the amplitude and phase of the line voltage, as well as the amplitude and phase of the phase current, are systematically measured and recorded for different speeds and rotor position angles. To eliminate individual differences, multiple motors of the same model are tested and averaged. Finally, a detailed reference parameter mapping table is generated and embedded into the program.

[0058] Subsequently, the system begins to sample the motor line voltage and three-phase current under the current steady state in real time, and calculates the amplitude of these signals in real time using an algorithm. ) and phase ( Next, the real-time calculated values ​​are precisely compared with the reference values ​​for the corresponding speed and rotor position obtained from the reference table.

[0059] To quantify this difference in comparison, an evaluation function M is constructed using a weighted sum of squares method, and its calculation formula is as follows:

[0060] in, For the evaluation function, ~ These are the weighting coefficients. Indicates amplitude. Indicates phase, and These are the real-time sampled line voltage amplitude and line voltage phase, respectively. and These are the baseline voltage amplitude and phase, respectively, retrieved from a pre-stored table. The baseline voltage amplitude and phase are obtained through offline calibration of a normal motor. and These are the phase current amplitude and phase current phase sampled in real time, respectively. and These are the reference phase current amplitude and reference phase current phase obtained from a pre-stored table, respectively. The reference phase current amplitude and phase are obtained by a normal motor under offline calibration conditions.

[0061] Finally, the calculated evaluation function The results are compared with a preset failure threshold for follow-up examinations. If If the value exceeds this threshold, the inter-turn short-circuit fault is finally confirmed to exist, and the system can then implement higher-level safety policies (such as recording a permanent fault code, restricting system restarts, etc.); if If the value does not exceed the threshold, it indicates that the initial diagnosis may be a false alarm and the current electrical characteristics are consistent with those of a normal motor. The system can use this information to clear the fault alarm or restore some operating capacity, thereby effectively avoiding power loss caused by misjudgment in a single diagnostic step.

[0062] Preferably, the application objects of the present invention include, but are not limited to, three-phase, five-phase, six-phase, dual three-phase, and open-winding permanent magnet synchronous motors; the inverter topologies include, but are not limited to, two-level, three-level, and cascaded; the safety strategies after a short circuit include, but are not limited to, active three-phase short circuit, active disconnection of the drive shaft to prevent motor rotation, active reduction of permanent magnet flux linkage, and active disconnection of the neutral point of the star-connected permanent magnet motor.

[0063] The method proposed in this invention uses a variety of characteristic signals to diagnose the location of short circuits, including characteristic current and characteristic line voltage, which can improve the reliability of diagnosis. By extracting and analyzing the characteristic signals, three-phase active short circuits can be performed at special locations (such as peak current and peak line voltage), achieving flexible conversion to three phases, minimizing transient current impacts, and ensuring system safety.

[0064] According to another aspect of the embodiments of this application, an electronic device is also provided, including a processor and a memory, wherein the processor is configured to implement the steps of the method when executing a computer program stored in the memory.

[0065] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0066] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0067] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0068] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for active short-circuit control of a permanent magnet synchronous motor, characterized in that, Includes the following steps: Acquire analog signals from the permanent magnet synchronous motor drive system; Based on the analog quantity, the back potential deviation signal is estimated using a back potential deviation observer. Based on the back EMF deviation signal, determine whether the inter-turn short-circuit fault characteristics exceed a preset threshold. If the value exceeds the limit, it is identified as an inter-turn short circuit fault; otherwise, it is determined whether there is inverter overcurrent or inverter module fault. Based on the identified short-circuit fault type, the location of the short circuit is diagnosed; Based on the diagnosed location of the short circuit, active short circuit control is implemented, including adjusting the three-phase output voltage to gradually decrease to zero for inter-turn short circuits inside the motor; and turning on the upper or lower three-phase transistors of the inverter at a set position for inter-phase short circuits. After identifying an inter-turn short-circuit fault and implementing active short-circuit control, an inter-turn short-circuit fault re-diagnosis is performed to finally confirm whether the fault exists.

2. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 1, characterized in that, Based on the analog quantity, the method for estimating the back potential deviation signal using a back potential deviation observer includes: Set the position angle of the resolver rotor; The reference back EMF deviation signal is calibrated offline using a normal motor under different voltages, speeds, and torques. The resolver rotor position angle and the reference back EMF deviation signal are input to the back EMF deviation observer, and the back EMF deviation signal is estimated based on the output of the back EMF deviation observer.

3. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 2, characterized in that, Methods for determining whether the characteristics of inter-turn short-circuit faults exceed a preset threshold include: The amplitude of the estimated back EMF deviation signal is calculated as a fault characteristic quantity; Determine whether the fault characteristic quantity exceeds a preset judgment threshold; If the value exceeds the limit, an inter-turn short circuit fault is determined; otherwise, an inverter overcurrent or inverter module fault is determined.

4. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 1, characterized in that, Methods for re-diagnosing inter-turn short-circuit faults include: Determine whether the permanent magnet synchronous motor is in a three-phase active short-circuit steady state; If a steady state is reached, the pre-stored reference electrical parameters, which were calibrated offline by a normal motor, are retrieved based on the current motor speed and rotor position. The amplitude and phase of the line voltage and phase current collected in real time are compared with the reference electrical parameters obtained in the query. An evaluation function is constructed based on the comparison results, and the existence of an inter-turn short circuit fault is finally confirmed based on the output of the evaluation function. The evaluation function is constructed using a weighted sum of squares method, and its calculation formula is as follows: in, For the evaluation function, ~ These are the weighting coefficients. Indicates amplitude. Indicates phase, and These are the real-time sampled line voltage amplitude and line voltage phase, respectively. and These are the baseline voltage amplitude and phase, respectively, retrieved from a pre-stored table. The baseline voltage amplitude and phase are obtained through offline calibration of a normal motor. and These are the phase current amplitude and phase current phase sampled in real time, respectively. and These are the reference phase current amplitude and reference phase current phase obtained from a pre-stored table, respectively. The reference phase current amplitude and phase are obtained by a normal motor under offline calibration conditions.

5. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 1, characterized in that, Methods for diagnosing the location of a short circuit based on the identified short circuit fault type include: If the fault is identified as an inter-turn short circuit fault inside the motor, the location of the short circuit is diagnosed as inside the permanent magnet synchronous motor. If an inverter overcurrent or inverter module fault is detected, the following diagnostic procedure will be executed: a) Control the disconnection of the isolation contactor to isolate the permanent magnet synchronous motor from the DC side of the inverter; b) After disconnection, if the current sensor reading is close to zero and the motor line voltage is normal, the short circuit location is diagnosed as the DC side of the inverter. c) If the collected three-phase currents show a phase-to-phase short-circuit characteristic current and the motor line voltage is abnormal, the short circuit location is diagnosed as the inverter bridge arm. d) If the current sensor reading is close to zero and the motor line voltage is abnormal, the short circuit location is diagnosed as the three-phase terminals of the motor.

6. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 5, characterized in that, Based on the diagnosed location of the short circuit, the methods for implementing active short circuit control include: If the location of the short circuit is diagnosed as an internal inter-turn short circuit in the motor, the control isolation contactor will remain closed, and the three-phase output voltage of the inverter will gradually decay to zero within a set time. If the location of the short circuit is diagnosed as a short circuit on the DC side of the inverter, the inverter's pulse signal will be immediately blocked and the isolation contactor will be disconnected. If the short circuit location is diagnosed as a short circuit in the inverter bridge arm or a short circuit in the three-phase terminals of the motor, the control isolation contactor is kept closed. Then, the electrical characteristics of the motor line voltage or stator current are identified, and when the electrical characteristics reach a preset predetermined position, the three-phase upper or lower transistors of the inverter are simultaneously turned on.

7. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 6, characterized in that, Methods for gradually reducing the three-phase output voltage of an inverter to zero within a set time include: Determine if the motor's rotary transformer is faulty; If the rotary transformer fails, the motor control system will be switched to a sensorless control mode. The two orthogonal components of the inverter's current output voltage vector in the synchronous rotating coordinate system at the switching moment are used as initial values; Within a first set time period, the phase of the output voltage vector is adjusted so that one of its orthogonal components is linearly reduced to zero, while the amplitude of the output voltage vector remains unchanged. After the orthogonal component is reduced to zero, another orthogonal component is linearly reduced to zero within a second set time period.

8. The active short-circuit control method for a permanent magnet synchronous motor as described in claim 6, characterized in that, When the electrical characteristic reaches a preset predetermined position, the simultaneous conduction of either the three-phase upper transistor or the three-phase lower transistor of the inverter is achieved through any of the following methods: The motor line voltage is collected, and a conduction operation is performed when any phase line voltage reaches its peak value or zero crossing point; or, the motor stator current is collected, and a conduction operation is performed when the stator current amplitude reaches its peak value.

9. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store programs that support the processor in executing the active short-circuit control method for the permanent magnet synchronous motor according to any one of claims 1-8, and the processor is configured to execute the programs stored in the memory.

10. A computer-readable storage medium storing a computer program thereon, characterized in that, When the computer program is run by the processor, it executes the steps of the active short-circuit control method for permanent magnet synchronous motors according to any one of claims 1-8.

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