System and method for pre-adjusting zero of new energy automobile motor rotor

Abstract

The application discloses a system and method for pre-adjusting zero of a motor rotor of a new energy vehicle, and relates to the technical field of new energy motor manufacturing. The system core comprises a PLC logic control unit, a relay isolation driving unit, an alternating current contactor execution unit, a high-precision adjustable constant current source unit and a rotor position detection unit, bidirectional communication is established between the PLC and the constant current source, the relay and the contactor are used to control the on-off of the power supply circuit and the phase sequence switching, and a double closed-loop control architecture is constructed in combination with real-time feedback of the rotor position, so that the full-process automation execution of rotor driving, position monitoring and zero calibration can be automatically completed without manual operation, the industry pain points of insufficient precision, poor universality, low production efficiency and weak operation reliability of the existing pre-adjusting zero system are solved, the pre-adjusting zero calibration precision and the equipment flexible adaptation capability are greatly improved, and the operation efficiency is improved, and the system is fully suitable for the large-scale and flexible mass production demand of new energy motors.

Description

Technical Field

[0001] This invention relates to the field of new energy motor manufacturing technology, specifically to a system and method for pre-zeroing the rotor of a new energy vehicle motor. Background Technology

[0002] With the rapid development of the global new energy vehicle industry, permanent magnet synchronous motors (PMSMs) have become the absolute mainstream solution for new energy vehicle drive systems due to their core advantages such as high power density, high energy conversion efficiency, wide speed range, and low operating noise. Their manufacturing precision and performance consistency directly determine the power performance, range, driving safety, and driving experience of new energy vehicles. In the mass production process of PMSMs, rotor initial position pre-zeroing is a core and critical process that runs through the entire process of motor assembly and off-line testing. Its process precision and operational efficiency directly determine the upper limit of the motor's performance and its mass production delivery capability.

[0003] Specifically, the high-performance control of new energy permanent magnet synchronous motors relies on field-oriented control (FOC, vector control) technology. The core premise of this technology is the real-time and precise acquisition of the absolute electrical position of the rotor permanent magnets. This allows for precise phase control of the stator three-phase current, maintaining the optimal torque output angle between the stator rotating magnetic field and the rotor permanent magnet magnetic field, ultimately achieving high-precision closed-loop control of the motor's instantaneous speed and output torque. However, during motor assembly, the pressing of the rotor permanent magnets to the motor shaft, and the installation of the position sensor (mainly a reluctance rotary transformer in the industry), stator, and motor end cover inevitably introduce mechanical assembly tolerances. This results in a fixed angular offset between the theoretical d-axis electrical zero position of the rotor permanent magnets (the central axis of the permanent magnet's N pole, i.e., the absolute reference for motor magnetic field control) and the output zero position of the position sensor. This angular offset is stored in the motor controller's storage unit as a unique parameter for each motor, used to compensate for the original angle and eliminate assembly tolerances. If the offset is not accurately calibrated before the motor is put into use, the motor controller will be unable to obtain the true position of the rotor through sensor readings, which will directly lead to the failure of vector control decoupling and greatly affect the performance of new energy vehicles.

[0004] Rotor pre-zeroing is the core technology for precisely calibrating this offset. Its core principle is as follows: by applying a large DC current with a specific phase sequence and fixed amplitude to the three-phase stator windings of the motor, a composite DC magnetomotive force with a constant spatial position is generated in the stator windings. Under the action of electromagnetic torque, the rotor permanent magnets are forcibly pulled and locked to an equilibrium position that completely coincides with the axis of the stator's composite magnetomotive force—this position is the motor's preset theoretical d-axis electrical zero position. After the rotor is completely stable and locked, the real-time output angle of the position sensor is collected, and the fixed offset between the sensor zero position and the rotor's actual zero position can be calculated. This offset will serve as the sole reference for the controller to perform position calculations and closed-loop control throughout the motor's entire life cycle.

[0005] Therefore, the precision and reliability of the pre-zeroing process are the fundamental prerequisites for achieving high-performance control of permanent magnet synchronous motors, and its importance is reflected in three core dimensions: First, it determines the basic control accuracy of the motor. The calibration deviation of the pre-zero adjustment will become a permanent reference error for motor control, which will directly lead to the phase shift of the stator current, causing problems such as insufficient motor output torque, reduced energy efficiency, running vibration, and increased temperature rise. In severe cases, it may even cause fatal safety failures such as incorrect torque direction and rotor runaway.

[0006] Secondly, it ensures the performance consistency of mass-produced motors. Assembly tolerances for motors of the same model vary from unit to unit. Only by precisely pre-zeroing each individual motor can performance fluctuations caused by individual assembly deviations be eliminated, ensuring that mass-produced motors have consistent power performance and control characteristics.

[0007] Thirdly, it supports the safe implementation of the vehicle's functions. The core functions of new energy vehicles, such as hill-start parking, low-speed crawling, intelligent driving torque control, and regenerative braking, all rely on obtaining the precise rotor position at the moment the motor is powered on. The offset of the pre-adjusted zero calibration is the core foundation for the controller to obtain the absolute position immediately upon power-on, which is directly related to the driving safety and functional stability of the entire vehicle.

[0008] Currently, the systems and processes for pre-zeroing the rotors of new energy vehicle motors used in the industry are all based on the aforementioned zero-locking calibration principle. However, in actual mass production applications, many intractable technical defects have been exposed, which have become the core bottleneck restricting the improvement of mass production efficiency and finished product quality of new energy motors. Specifically, they are as follows: ① Insufficient pre-adjustment zero control accuracy makes it difficult to meet the high-precision calibration requirements of high-end new energy motors: Most existing pre-zeroing systems employ open-loop current control, where the core control unit only issues target current commands to the current output device without real-time acquisition and closed-loop correction of the actual output current. This fails to eliminate current amplitude deviations caused by factors such as grid voltage fluctuations, changes in motor winding internal resistance with temperature rise, and differences in line contact impedance. Furthermore, the accuracy of the pre-zeroing lock position depends entirely on the direction and amplitude stability of the stator's synthesized magnetomotive force (MTF). If the amplitude ratio of the three-phase output current deviates from the preset value, it directly causes the axis of the stator's synthesized MMF to deviate from the theoretical d-axis zero position, essentially resulting in a fixed deviation in the lock-in reference itself. Simultaneously, current output fluctuations under open-loop control lead to unstable lock-in electromagnetic torque, preventing the rotor from fully overcoming cogging torque and frictional resistance to achieve precise lock-in, easily resulting in residual deviations in the lock-in position. In addition, some systems lack real-time closed-loop feedback of rotor position, making it impossible to accurately determine the rotor lock-in state and the timing of zero-position arrival. This easily leads to problems such as signal acquisition lag and shutdown timing deviations, further amplifying the calibration error of the pre-zeroing. Ultimately, insufficient pre-adjustment zero precision will directly lead to a decrease in the control precision of the finished motor, and may even cause quality hazards such as irreversible demagnetization of permanent magnets and overheating and burning of windings.

[0009] ② The system has extremely poor versatility and applicability, and cannot meet the flexible mass production requirements of new energy motors: Existing pre-zeroing systems are mostly dedicated equipment, designed and developed for a single specification and model of motor. Their constant current source output range is fixed, and their control logic and power-on timing are fixed, enabling them to only perform pre-zeroing operations on motors of a preset model. However, the current new energy vehicle market is iterating rapidly, and a single production line often needs to be compatible with the production of multiple motors with different power, specifications, and pole pairs. When changing models, existing systems require readjusting hardware wiring, modifying control programs, and debugging equipment parameters, resulting in long changeover cycles and high debugging costs. This makes it impossible to achieve rapid compatibility and adaptation for multiple motor specifications, severely restricting the flexible production capacity of the production line.

[0010] ③ The system has a low degree of automation, cumbersome operation procedures, and low mass production efficiency: Some existing pre-zeroing systems still use a semi-manual operation mode. From motor wiring, parameter setting, power-on start and stop to position acquisition and deviation calibration, many key links require manual intervention. The pre-zeroing operation cycle of a single motor is long, and the error rate of manual operation is high. Problems such as parameter setting errors and wiring mistakes are prone to occur, resulting in a high rework rate.

[0011] Most importantly, the existing system has a complex debugging process. For different motors, the pre-zeroing requirements require technicians to write control programs and debug the power-on and power-off timing separately, resulting in a particularly long initial deployment cycle.

[0012] It is particularly noteworthy that most systems do not integrate automated accuracy verification and data traceability functions. After calibration, manual verification using testing equipment is required, which further lengthens the operation cycle and cannot meet the needs of large-scale, mass production of new energy motors, significantly increasing the production and manufacturing costs of motors.

[0013] ④ The system lacks reliability and security, has a high failure rate, and incurs high maintenance costs. In some existing pre-zeroing systems, the control circuit and the high-voltage power supply circuit are not effectively electrically isolated. The control unit directly drives the high-voltage circuit to switch on and off. The high-voltage surges and electromagnetic interference from the motor drive can easily enter the low-voltage control circuit, causing the control core to crash, signal acquisition distortion, and I / O port damage, which seriously affects the stability of system operation. At the same time, most systems lack a complete real-time fault diagnosis and protection mechanism, and cannot quickly identify and shut down problems such as communication interruption, abnormal current, device failure, and wiring short circuit. This can easily lead to safety accidents such as equipment damage and motor scrapping. Moreover, after a fault occurs, there is a lack of clear fault indication and location, requiring manual troubleshooting. The downtime is long, which further affects the continuous operation efficiency of the production line and increases the operation and maintenance costs of the equipment.

[0014] In summary, the existing rotor pre-zeroing system for new energy vehicle motors can no longer meet the mass production demands for high precision, flexibility, high efficiency, and high reliability brought about by the rapid development of the current new energy motor industry. Therefore, how to comprehensively solve the current industry pain points has always been a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0015] The purpose of this invention is to address the shortcomings of existing technologies by providing a system and method for pre-zeroing the rotor of a new energy vehicle motor. The system includes a PLC logic control unit, a relay isolation drive unit, an AC contactor execution unit, a high-precision adjustable constant current source unit, and a rotor position detection unit. The PLC establishes bidirectional communication with the constant current source, and the relays and contactors control the on / off state of the power supply circuit and phase sequence switching. Combined with real-time rotor position feedback, a dual closed-loop control architecture is constructed. This enables fully automated execution of the entire process of rotor drive, position monitoring, and zero-position calibration without human intervention. It completely solves the industry pain points of insufficient accuracy, poor versatility, low production efficiency, and weak operational reliability of existing pre-zeroing systems, significantly improving the accuracy of pre-zeroing calibration, the flexibility of equipment, and operational efficiency, thereby fully adapting to the large-scale, flexible mass production needs of new energy motors.

[0016] The objective of this invention is achieved through the following approach: A system for pre-zeroing the rotor of a motor in a new energy vehicle includes a PLC logic control unit, a relay isolation drive unit, an AC contactor execution unit, a high-precision adjustable constant current source unit, and a rotor position detection unit. The digital output terminal of the PLC logic control unit is electrically connected to the control input terminal of the relay isolation drive unit. The PLC logic control unit establishes a bidirectional communication connection with the high-precision adjustable constant current source unit through a serial communication interface. The signal input terminal of the PLC logic control unit is connected to the rotor position detection unit. The output contacts of the relay isolation drive unit are connected to the coil control circuit of the AC contactor actuator unit, enabling the relay isolation drive unit to control the on / off state of the AC contactor according to the IO signals of the PLC logic control unit. The main contacts of the AC contactor actuator are connected in series between the high-precision adjustable constant current source unit and the three-phase power supply circuit of the new energy motor to be pre-adjusted to zero, and are used to control the on / off of the power supply circuit and the switching of the energizing phase sequence. The power output terminal of the high-precision adjustable constant current source unit is connected to the three-phase winding terminals of the new energy motor that requires pre-zeroing via an AC contactor, in order to provide the motor with the stable DC excitation current required for pre-zeroing.

[0017] Preferably, the high-precision adjustable constant current source unit communicates with the PLC logic control unit through an RS232 serial communication interface to receive current control commands issued by the PLC logic control unit and to transmit the actual output current value, equipment operating status and fault alarm information back to the PLC logic control unit in real time. The high-precision adjustable constant current source unit is a DC constant current source that is continuously adjustable from 0 to 120A, with a current control accuracy of ≤ ±0.5%FS, and supports independent ratio adjustment of the three-phase output current.

[0018] Preferably, the relay isolation drive unit includes multiple sets of relays, with the coil input terminal of a single set of relays electrically connected to the digital output terminal corresponding to the PLC logic control unit, and the normally open output contacts of the relays connected in series to the coil power supply circuit of the corresponding AC contactor.

[0019] Preferably, the AC contactor execution unit includes multiple sets of AC contactors. Each set of contactors corresponds to the power supply circuit of one phase winding of the motor. The multiple sets of contactors correspond one-to-one with relays, so that the PLC logic control unit can drive the on / off combination of the corresponding contactors by controlling the on / off timing of different relays, thereby switching the energizing phase sequence of the constant current source and the three-phase winding of the motor.

[0020] Preferably, the PLC logic control unit has a built-in pre-zeroing full-process automated control program, which includes an initialization program module, a parameter setting program module, a communication interaction program module, a closed-loop control program module, and a fault diagnosis program module. The initialization program module is used to initialize and reset the PLC's internal registers, communication parameters, and IO port status after the system for pre-zeroing the rotor of the new energy vehicle motor is powered on, ensuring that the system is in a safe standby state after power-on. The parameter setting program module is used to receive and store the pre-adjustment zero parameters input by the operator; The communication interaction program module is used to realize the control command issuance and status data feedback processing between the PLC and the constant current source; The closed-loop control program module is used to execute the entire process logic of relay and contactor on / off control, rotor forward and reverse rotation drive, zero position deviation judgment, and lock-up calibration based on the pre-adjustment zero parameters and rotor position real-time feedback signals. The fault diagnosis program module is used to monitor the system's full-dimensional operating status in real time, and execute emergency shutdown logic and trigger alarms when a fault is triggered.

[0021] Preferably, the parameter setting program module supports the storage and one-click recall of pre-zero adjustment process recipes for multiple motor models. The pre-zero adjustment process recipes include target current ratio parameters, forward and reverse control timing, zero position deviation threshold, lock-up stability judgment duration, and protection parameters.

[0022] Preferably, the PLC logic control unit has a built-in data storage and traceability module for automatically storing the zero offset of the pre-zero calibration of a single motor, process parameters, equipment operating data, and fault information, and supports data uploading and full-process traceability by connecting to the production line management system.

[0023] A method for pre-zeroing a new energy rotor using the above system includes the following steps: S1) Connect the three-phase windings of the new energy motor that needs to be pre-zeroed to the output terminal of the AC contactor, and connect the signal output terminal of the motor's rotary transformer to the rotor position detection unit. S2) Select the pre-zero adjustment process formula for the corresponding motor model through the human-machine interface, or manually set the pre-zero adjustment parameters; S3) The PLC sends a pre-adjustment zero current control command to the high-precision adjustable constant current source; S4) The PLC outputs IO signals to control the corresponding relays and contactors to close, thus connecting the power supply circuit of the constant current source and the motor. The constant current source outputs a preset DC current to drive the motor rotor to rotate. At the same time, the PLC collects the rotor position signal in real time through the rotor position detection unit, continuously monitors the deviation between the rotor and the theoretical d-axis zero position, and controls the rotor to rotate forward or reverse for fine adjustment by switching the contactor on / off combination until the PLC determines that the rotor has reached the theoretical d-axis electrical zero position. S5) Latch the real-time output angle of the rotary transformer and automatically calculate and store the rotor zero-position offset.

[0024] Preferably, in step S4), the specific rules for the PLC to determine that the rotor has reached the theoretical d-axis electrical zero position include: The PLC calculates the deviation between the current rotor position and the theoretical d-axis zero position in real time. When the deviation value enters the preset zero position deviation threshold range, the lock-up stabilization timer is started. If the rotor position fluctuation amplitude continues to be within the preset zero position deviation threshold range within the preset lock-up stabilization judgment time, it is determined that the rotor has been stably locked at the theoretical d-axis electrical zero position.

[0025] Preferably, throughout the entire process from steps S1) to S5), the fault diagnosis program preset in the PLC logic control unit monitors the system's operating status in real time. When communication interruption, abnormal current, abnormal device operation, abnormal rotor position, or emergency stop triggering fault is detected, the preset automatic emergency stop processing scheme is immediately executed, cutting off all relay outputs and constant current source outputs, while triggering on-site alarms and outputting fault location information.

[0026] The beneficial effects of this invention are as follows: A system for pre-zeroing the rotor of a motor in a new energy vehicle includes a PLC logic control unit, a relay isolation drive unit, an AC contactor execution unit, a high-precision adjustable constant current source unit, and a rotor position detection unit. The digital output terminal of the PLC logic control unit is electrically connected to the control input terminal of the relay isolation drive unit. The PLC logic control unit establishes a bidirectional communication connection with the high-precision adjustable constant current source unit through a serial communication interface. The signal input terminal of the PLC logic control unit is connected to the rotor position detection unit. The output contacts of the relay isolation drive unit are connected to the coil control circuit of the AC contactor actuator unit, enabling the relay isolation drive unit to control the on / off state of the AC contactor according to the IO signals of the PLC logic control unit. The main contacts of the AC contactor actuator are connected in series between the high-precision adjustable constant current source unit and the three-phase power supply circuit of the new energy motor to be pre-adjusted to zero, and are used to control the on / off of the power supply circuit and the switching of the energizing phase sequence. The power output terminal of the high-precision adjustable constant current source unit is connected to the three-phase winding terminals of the new energy motor that requires pre-zeroing via an AC contactor, in order to provide the motor with the stable DC excitation current required for pre-zeroing.

[0027] Therefore, this invention addresses four core pain points in the industry by constructing a novel, fully closed-loop integrated system architecture encompassing "control core - electrical isolation - actuator - energy supply - position feedback." Specifically: (1) This invention establishes a bidirectional communication link between the PLC and the constant current source, providing a hardware foundation for current closed-loop control and fundamentally solving the problems of zero-locking reference deviation and insufficient pre-zeroing accuracy caused by the open-loop current control of the existing technology. (2) This invention designs a two-level drive architecture of "PLC-relay-AC contactor", which realizes dual electrical isolation between the weak current control circuit and the strong current main circuit, and solves the defects of existing systems such as strong current interference, high failure rate and insufficient reliability. (3) This invention integrates a real-time rotor position feedback link, providing hardware support for closed-loop control of rotor position and precise zero-position determination, and solving the problems of locking position deviation and data acquisition timing errors caused by open-loop timing control in the prior art. (4) This invention adopts a combination architecture of programmable PLC control core and adjustable constant current source, which provides a core carrier for flexible adaptation of multi-specification motors and full-process automated control, and solves the pain points of poor universality, cumbersome operation and low production efficiency of existing systems.

[0028] Preferably, the high-precision adjustable constant current source unit communicates with the PLC logic control unit through an RS232 serial communication interface to receive current control commands issued by the PLC logic control unit and to transmit the actual output current value, equipment operating status and fault alarm information back to the PLC logic control unit in real time. The high-precision adjustable constant current source unit is a DC constant current source that is continuously adjustable from 0 to 120A, with a current control accuracy of ≤ ±0.5%FS, and supports independent ratio adjustment of the three-phase output current.

[0029] In this invention, the key parameters and functions of the constant current source are crucial for solving the two major defects of insufficient pre-adjustment accuracy and poor versatility. For example: (1) The output capability of 0~120A is continuously adjustable in a wide range, which can cover the pre-adjusted zero current requirements of new energy vehicles from small power auxiliary motors to high power main drive motors. It can be adapted to different specifications of motors without changing hardware, greatly improving the system's versatility and flexible production adaptability. (2) The two-way communication mechanism realizes the full closed-loop control of current output. The PLC can correct the issued control command in real time according to the actual current value returned by the constant current source, completely eliminate the current deviation caused by grid voltage fluctuation, winding internal resistance temperature rise and line contact impedance difference, ensure that the amplitude and ratio of the three-phase current are completely in line with the preset value, and ensure that the stator synthesized magnetomotive force axis is accurately aligned with the theoretical d-axis zero position, thus eliminating the zero-locking reference deviation from the root. (3) High-precision current control with a margin of ≤±0.5%FS can ensure the continuous stability of the zero-locking electromagnetic torque, avoid rotor vibration and insecure locking caused by current fluctuations, and further improve the calibration accuracy and batch consistency of pre-zero adjustment.

[0030] Preferably, the relay isolation drive unit includes multiple sets of relays, with the coil input terminal of a single set of relays electrically connected to the digital output terminal corresponding to the PLC logic control unit, and the normally open output contacts of the relays connected in series to the coil power supply circuit of the corresponding AC contactor.

[0031] This invention uses a relay isolation drive unit as the core component for electrical isolation, addressing the technical deficiencies of existing systems such as insufficient reliability and weak anti-interference capabilities. It achieves complete electrical isolation between the low-voltage control circuit (e.g., DC24V) where the PLC resides and the high-voltage control circuit where the AC contactor resides. The relay coil circuit and contact circuit transmit signals only through magnetic coupling, without direct electrical connection. This completely eliminates surges, impacts, and electromagnetic interference from high-voltage circuits from entering the PLC control core, preventing PLC crashes, I / O port damage, signal acquisition distortion, and other malfunctions. It ensures the operational safety and stability of the control core from a hardware perspective.

[0032] Most importantly, this invention also realizes the signal amplification function of "low-power control signal driving high-power load". With the milliampere-level IO output signal of PLC, it reliably drives the coil circuit of AC contactor, accurately transmits the on and off control commands of PLC, ensures the accuracy of control timing, and avoids the problem of "control signal distortion, resulting in the final calibration accuracy not meeting the requirements".

[0033] Preferably, the AC contactor execution unit includes multiple sets of AC contactors. Each set of contactors corresponds to the power supply circuit of one phase winding of the motor. The multiple sets of contactors correspond one-to-one with relays, so that the PLC logic control unit can drive the on / off combination of the corresponding contactors by controlling the on / off timing of different relays, thereby switching the energizing phase sequence of the constant current source and the three-phase winding of the motor.

[0034] This invention uses an AC contactor actuator as the core architecture of the high-voltage circuit actuator, which is an important design for achieving flexible rotor control and improving pre-zero adjustment accuracy. It not only flexibly switches the energizing phase sequence and current flow of the three-phase windings by independently controlling the on / off combinations of multiple contactors, achieving the technical effect of "multi-mode control of the motor rotor—forward drive, reverse fine-tuning, and stable locking—without modifying hardware wiring or motor tooling connections, providing hardware support for precise rotor position correction, eliminating overshoot and jamming deviations, and further improving zero-locking accuracy," but also allows the use of industrial-grade high-current contactors to adapt to the frequent on / off requirements of high-current pre-zero adjustment conditions. Their built-in arc-extinguishing structure avoids contact erosion during high-current interruption, improving the service life and operational safety of the system equipment to meet the high-frequency operation requirements of mass production lines.

[0035] Preferably, the PLC logic control unit has a built-in pre-zeroing full-process automated control program, which includes an initialization program module, a parameter setting program module, a communication interaction program module, a closed-loop control program module, and a fault diagnosis program module. The initialization program module is used to initialize and reset the PLC's internal registers, communication parameters, and IO port status after the system for pre-zeroing the rotor of the new energy vehicle motor is powered on, ensuring that the system is in a safe standby state after power-on. The parameter setting program module is used to receive and store the pre-adjustment zero parameters input by the operator. The communication interaction program module is used to realize the control command issuance and status data feedback processing between the PLC and the constant current source; The closed-loop control program module is used to execute the entire process logic of relay and contactor on / off control, rotor forward and reverse rotation drive, zero position deviation judgment, and lock-up calibration based on the pre-adjustment zero parameters and rotor position real-time feedback signals. The fault diagnosis program module is used to monitor the system's full-dimensional operating status in real time, and execute emergency shutdown logic and trigger alarms when a fault is triggered.

[0036] In this invention, the PLC logic control unit includes a PLC control chip. The core software architecture built into this PLC control chip is the key to realizing the full automation of the pre-zero adjustment process, improving production efficiency, and ensuring operational safety. It has the following three functions for the pre-zero adjustment of the motor rotor: (1) The modular automated control program realizes the fully automated execution of the entire process from parameter configuration, circuit on / off, rotor drive, position monitoring to zero-position calibration and circuit cut-off. Operators only need to complete the motor clamping and start command triggering without manual intervention in the intermediate links, which greatly shortens the pre-zeroing operation cycle of a single motor, and completely avoids calibration errors caused by human operation errors, thereby improving production efficiency and the first-pass yield of pre-zeroing. (2) The full-cycle fault diagnosis and protection mechanism can realize real-time monitoring and rapid handling of faults during the entire process of system power-on, pre-zeroing execution and standby. When a fault occurs, all energy output is immediately cut off to avoid safety accidents such as equipment damage and motor scrapping. At the same time, it can realize accurate fault identification, reduce the difficulty of operation and maintenance and troubleshooting and downtime. (3) Modular programming allows the core control logic to be flexibly adjusted through parameter configuration, adapting to different pre-adjustment requirements without modifying the underlying program, greatly reducing the difficulty of debugging and deployment of new models.

[0037] Preferably, the parameter setting program module supports the storage and one-click recall of pre-zero adjustment process recipes for multiple motor models. The pre-zero adjustment process recipes include target current ratio parameters, forward and reverse control timing, zero position deviation threshold, lock-up stability judgment duration, and protection parameters.

[0038] Based on the actual motor rotor pre-zeroing process, this invention constructs a corresponding process formula management function in the system, which is the core design to solve the problems of poor versatility and low changeover efficiency of existing motor rotor pre-zeroing systems.

[0039] Specifically, the process formula management function solidifies the mature pre-adjustment zero process parameters of motors of different specifications and models into standardized formulas and stores them in the PLC. When the production line changes models, the operators do not need to modify the underlying control program or adjust the hardware wiring. They can simply call the corresponding formula with one click to complete the equipment changeover, shortening the changeover cycle from several hours in the existing technology to minutes, perfectly adapting to the flexible mass production needs of new energy motors with multiple varieties and rapid iteration. Most importantly, standardized formula management can avoid errors in manual parameter setting, ensure the consistency of the pre-zeroing process for motors of the same model, improve the calibration accuracy and stability of mass production and the consistency of finished motor performance, and reduce mass production quality control costs.

[0040] Preferably, the PLC logic control unit has a built-in data storage and traceability module for automatically storing the zero offset of the pre-zero calibration of a single motor, process parameters, equipment operating data, and fault information, and supports data uploading and full-process traceability by connecting to the production line management system.

[0041] Based on actual production conditions, this invention designs a data management function for mass production adaptation. This is an important design to meet the needs of large-scale production. It not only realizes the automated storage and recording of core data for pre-zero adjustment of a single motor, eliminating the need for manual recording and organization of calibration data, further reducing manual operation steps, improving mass production efficiency, and avoiding errors in manual recording, but also allows direct connection to the production line management system to achieve full-process traceability of pre-zero adjustment data. This provides complete data support for the quality control of finished motor products, after-sales fault tracing, and process optimization, meeting the quality management requirements for large-scale mass production of new energy motors.

[0042] A method for pre-zeroing a new energy rotor using the above system includes the following steps: S1) Connect the three-phase windings of the new energy motor that needs to be pre-zeroed to the output terminal of the AC contactor, and connect the signal output terminal of the motor's rotary transformer to the rotor position detection unit. S2) Select the pre-zero adjustment process formula for the corresponding motor model through the human-machine interface, or manually set the pre-zero adjustment parameters; S3) The PLC sends a pre-adjustment zero current control command to the high-precision adjustable constant current source; S4) The PLC outputs IO signals to control the corresponding relays and contactors to close, thus connecting the power supply circuit of the constant current source and the motor. The constant current source outputs a preset DC current to drive the motor rotor to rotate. At the same time, the PLC collects the rotor position signal in real time through the rotor position detection unit, continuously monitors the deviation between the rotor and the theoretical d-axis zero position, and controls the rotor to rotate forward or reverse for fine adjustment by switching the contactor on / off combination until the PLC determines that the rotor has reached the theoretical d-axis electrical zero position. S5) Latch the real-time output angle of the rotary transformer and automatically calculate and store the rotor zero-position offset.

[0043] The new energy rotor pre-zeroing method implemented by the above-mentioned system in this invention fully covers the entire process from preparation, configuration, self-inspection, driving, calibration to completion. It transforms the hardware advantages of this system into a feasible pre-zeroing process method, realizing the full-process automation and closed-loop execution of pre-zeroing operation, and completely solving the problems of cumbersome semi-manual operation, low efficiency and high error rate in the existing technology.

[0044] Moreover, this invention integrates dual closed-loop logic of current closed-loop control and rotor position closed-loop monitoring, and adjusts the control strategy in real time during rotor driving. It eliminates position deviation by fine-tuning in both forward and reverse directions, which greatly improves the accuracy of pre-adjustment zero calibration and solves the major technical defects of insufficient accuracy and poor consistency in the prior art.

[0045] Preferably, in step S4), the specific rules for the PLC to determine that the rotor has reached the theoretical d-axis electrical zero position include: The PLC calculates the deviation between the current rotor position and the theoretical d-axis zero position in real time. When the deviation value enters the preset zero position deviation threshold range, the lock-up stabilization timer is started. If the rotor position fluctuation amplitude continues to be within the preset zero position deviation threshold range within the preset lock-up stabilization judgment time, it is determined that the rotor has been stably locked at the theoretical d-axis electrical zero position.

[0046] This invention employs a dual judgment rule of "deviation threshold + stabilization time", which not only determines whether the rotor position has entered the zero position range, but also verifies whether the rotor has completely overcome the cogging torque, frictional resistance, etc. to achieve stable locking. This effectively avoids calibration errors caused by the sampling angle when the rotor swings or is not fully locked, and further improves the calibration accuracy of the zero position offset. It is worth noting that the "zero deviation threshold" and "locking stability judgment time" in this invention can be flexibly configured through the process formula, which can be adapted to the locking characteristics of motors of different specifications, thereby improving the calibration accuracy and maximizing the work efficiency.

[0047] Preferably, throughout the entire process from steps S1) to S5), the fault diagnosis program preset in the PLC logic control unit monitors the system's operating status in real time. When communication interruption, abnormal current, abnormal device operation, abnormal rotor position, or emergency stop triggering fault is detected, the preset automatic emergency stop processing scheme is immediately executed, cutting off all relay outputs and constant current source outputs, while triggering on-site alarms and outputting fault location information.

[0048] The full-process fault monitoring and emergency shutdown mechanism designed in this invention can quickly identify abnormalities and perform safe handling at any stage of pre-zeroing, minimizing equipment damage, motor failure, and personnel safety risks, and improving the safety and reliability of system operation. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of the new energy vehicle motor rotor pre-zeroing system described in this invention; Figure 2 This is a flowchart illustrating the new energy rotor pre-zeroing method described in this invention; Figure 3 This is a schematic diagram of an embodiment of the present invention. Detailed Implementation

[0050] like Figures 1 to 2 As shown, a system for pre-zeroing the rotor of a new energy vehicle motor includes a PLC logic control unit, a relay isolation drive unit, an AC contactor execution unit, a high-precision adjustable constant current source unit, and a rotor position detection unit. The high-precision adjustable constant current source unit communicates with the PLC logic control unit through the RS232 serial communication interface. It is used to receive current control commands issued by the PLC logic control unit and to transmit the actual output current value, equipment operating status and fault alarm information back to the PLC logic control unit in real time. The high-precision adjustable constant current source unit is a DC constant current source that is continuously adjustable from 0 to 120A, with a current control accuracy of ≤ ±0.5%FS, and supports independent ratio adjustment of the three-phase output current.

[0051] The relay isolation drive unit includes multiple sets of industrial-grade intermediate relays. The coil input terminal of each relay is electrically connected to the corresponding digital output terminal of the PLC logic control unit. The normally open output contacts of the relays are connected in series to the coil power supply circuit of the corresponding AC contactor. For example, the coil power supply circuit and the PLC control circuit share a DC24V low-voltage power supply.

[0052] The AC contactor actuator unit includes multiple sets of industrial-grade high-current AC contactors. Each set of contactors corresponds to the power supply circuit of one phase winding of the motor. Multiple sets of contactors correspond one-to-one with relays, so that the PLC logic control unit can drive the on / off combination of the corresponding contactors by controlling the on / off timing of different relays, thereby switching the energizing phase sequence of the constant current source and the three-phase winding of the motor.

[0053] The digital output terminal of the PLC logic control unit is electrically connected to the control input terminal of the relay isolation drive unit. The PLC logic control unit establishes a bidirectional communication connection with the high-precision adjustable constant current source unit through a serial communication interface. The signal input terminal of the PLC logic control unit is connected to the rotor position detection unit used to acquire the real-time position of the motor rotor. The output contacts of the relay isolation drive unit are connected to the coil control circuit of the AC contactor execution unit, so that the relay isolation drive unit can control the on / off state of the AC contactor in the AC contactor execution unit according to the IO signal of the PLC logic control unit. The main contacts of the AC contactor actuator are connected in series between the high-precision adjustable constant current source unit and the three-phase power supply circuit of the new energy motor to be pre-adjusted to zero, and are used to control the on / off of the power supply circuit and the switching of the energizing phase sequence. The power output terminal of the high-precision adjustable constant current source unit is connected to the three-phase winding terminals of the new energy motor that requires pre-zeroing via an AC contactor, in order to provide the motor with the stable DC excitation current required for pre-zeroing.

[0054] Most importantly, the PLC logic control unit has a built-in pre-zeroing full-process automated control program, which includes an initialization program module, a parameter setting program module, a communication interaction program module, a closed-loop control program module, a fault diagnosis program module, and a data storage and traceability module. The initialization program module is used to initialize and reset the internal registers, communication parameters, and IO port status of the PLC in the PLC logic control unit after the system for pre-zeroing the rotor of the new energy vehicle motor is powered on, to ensure that the system is in a safe standby state after power-on. The parameter setting program module is used to receive and store the pre-zero adjustment parameters input by the operator. The parameter setting program module supports the storage and one-click recall of pre-zero adjustment process recipes for multiple motor models. The pre-zero adjustment process recipes include target current ratio parameters, forward and reverse control timing, zero position deviation threshold, lock-up stability judgment duration, and protection parameters.

[0055] The communication interaction program module is used to realize the control command issuance and status data feedback processing between the PLC and the constant current source; The closed-loop control program module is used to execute the entire process logic of relay and contactor on / off control, rotor forward and reverse rotation drive, zero position deviation judgment, and lock-up calibration based on the pre-adjustment zero parameters and rotor position real-time feedback signals. The fault diagnosis program module is used to monitor the system's full-dimensional operating status in real time, and execute emergency shutdown logic and trigger alarms when a fault is triggered.

[0056] The data storage and traceability module is used to automatically store the zero offset, process parameters, equipment operation data, and fault information of a single motor's pre-zero calibration, and supports data upload and full-process traceability by connecting to the production line management system (MES).

[0057] A method for pre-zeroing a new energy rotor using the above system includes the following steps: S1) Wiring preparation: Connect the three-phase windings of the new energy motor that needs to be pre-zeroed to the output terminal of the AC contactor, and connect the signal output terminal of the motor's rotary transformer to the rotor position detection unit to complete the hardware docking. S2) Parameter configuration: Select the pre-zero adjustment process formula for the corresponding motor model through the human-machine interface, or manually set the pre-zero adjustment parameters. The PLC completes parameter verification and storage. S3) System self-test and command issuance: The PLC performs a full-dimensional self-test of the system. After confirming that there are no abnormalities, it issues a pre-adjustment zero current control command to the high-precision adjustable constant current source to confirm that the constant current source is ready. S4) Rotor drive and position closed-loop monitoring: The PLC outputs IO signals to control the corresponding relays and contactors to close, and conducts the power supply circuit between the constant current source and the motor. The constant current source outputs a preset DC current to drive the motor rotor to rotate. At the same time, the PLC collects the rotor position signal in real time through the rotor position detection unit, continuously monitors the deviation between the rotor and the theoretical d-axis zero position, and controls the rotor to rotate forward or reverse for fine adjustment by switching the contactor on / off combination until the PLC determines that the rotor has reached the theoretical d-axis electrical zero position and is stably locked. In step S4), the specific rules for the PLC to determine that the rotor has reached the theoretical d-axis electrical zero position include: The PLC calculates the deviation between the current rotor position and the theoretical d-axis zero position in real time. When the deviation value enters the preset zero position deviation threshold range, the lock-up stabilization timer is started. If the rotor position fluctuation amplitude continues to be within the preset zero position deviation threshold range within the preset lock-up stabilization judgment time, it is determined that the rotor has been stably locked at the theoretical d-axis electrical zero position.

[0058] S5) Zero-position calibration and process completion: latch the real-time output angle of the rotary transformer, automatically calculate and store the rotor zero-position offset, and cut off the power supply circuit and constant current source output after calibration to complete the pre-zero adjustment operation.

[0059] Throughout the entire process from steps S1) to S5), the fault diagnosis program preset in the PLC logic control unit monitors the system's operating status in real time. When communication interruption, abnormal current, abnormal device operation, abnormal rotor position, or emergency stop triggering fault is detected, the preset automatic emergency stop handling plan is immediately executed, cutting off all relay outputs and constant current source outputs, while triggering on-site alarms and outputting fault location information. After the pre-zeroing operation is completed, the PLC automatically stores all the data of this operation synchronously and uploads it to the production line management system.

[0060] like Figure 3 As shown, based on the above method, the following is an embodiment. This embodiment takes the 80kW permanent magnet synchronous main drive motor, which is the mainstream mass-produced new energy vehicle, as the object of pre-zero adjustment. The motor has an 8-pole structure (p=4 pole pairs), a rated current of 120A, and is equipped with a reluctance rotary transformer as a rotor position sensor. Through the new energy vehicle motor rotor pre-zero adjustment system described in this invention, the high-precision and fully automated pre-zero adjustment calibration operation of the motor rotor is fully realized.

[0061] 1. System hardware setup and implementation The new energy vehicle motor rotor pre-zeroing system in this embodiment strictly follows the closed-loop architecture of "control core-electrical isolation-actuator-energy supply-position feedback" described in this invention. The specific selection, wiring, and functional implementation of each hardware unit are as follows: 1.1 PLC Logic Control Unit The core of this unit uses a Siemens S7-200 SMART SR40 PLC, which has 14 digital inputs and 10 digital outputs to meet the signal requirements of relay control, status feedback, and safety circuits. It expands with a CM01 RS232 signal board to achieve bidirectional communication with a constant current source; it also expands with an AE04 analog input module to connect to the position signals of the resolver decoding unit; and it is equipped with a Siemens KTP700 simplified panel as a human-machine interface unit, communicating with the PLC via a PROFINET interface to realize parameter configuration, recipe calling, status display, and fault alarm functions.

[0062] Meanwhile, this unit is connected to a resolver decoding module based on the AD2S1210 chip. The input of the resolver decoding module is connected to the output of the resolver of the motor to be pre-adjusted to zero. The decoded rotor real-time mechanical angle signal is transmitted to the PLC to provide real-time feedback for rotor position closed-loop control.

[0063] 1.2 Relay Isolation Drive Unit This unit uses four sets of DC24V industrial-grade intermediate relays (model: HH52P-L), designated KM1, KM2, KM3, and KM4 respectively. KM1-KM3 are three-phase main circuit control relays, and KM4 is a phase sequence fine-tuning relay. The positive terminal of each relay coil is connected to the corresponding digital output terminal (Q0.0-Q0.3) of the PLC, while the negative terminal is connected to the DC24V power ground. One end of the normally open output contact of the relay is connected to the AC220V control power supply, and the other end is connected to the coil input terminal of the corresponding AC contactor, achieving isolated driving of low-voltage to high-voltage.

[0064] 1.3 AC Contactor Actuation Unit This unit uses four sets of CJX2-1610 high-current AC contactors, with a main contact rated current of 160A, adapted to the output requirements of a 120A constant current source. The coil rated voltage is AC220V, corresponding one-to-one with four sets of relays. The input terminals of KM1, KM2, and KM3 main contactors are connected to the U, V, and W phase output terminals of the constant current source, respectively. The output terminals are connected to the three-phase winding terminals of the motor to be pre-adjusted via quick-connect fittings. The KM4 main contactor is used for switching the polarity of the V-phase current, realizing phase sequence adjustment for rotor forward and reverse rotation. All auxiliary normally open contacts of the contactors are connected to the PLC's digital input terminals (I0.0-I0.3), providing real-time feedback on the contact's on / off status to the PLC, achieving closed-loop verification of control commands and execution results.

[0065] 1.4 High-precision adjustable constant current source unit This unit employs a 0~120A continuously adjustable high-precision DC constant current source, with a current control accuracy ≤ ±0.3%FS. It supports independent three-phase current ratio output and features a built-in RS232 communication interface supporting the Modbus RTU communication protocol. The RS232 interface of the constant current source connects to the CM01 signal board of the PLC via a shielded communication cable, enabling bidirectional communication with the PLC. It can receive current setting and start / stop commands from the PLC and transmit data such as actual output current, operating status, and fault codes back to the PLC in real time. The three-phase power output terminals of the constant current source are reliably connected to the main contact input terminals of the AC contactor, providing a stable DC excitation current for motor pre-zero adjustment.

[0066] 1.5 Security and Cabling Implementation The system is equipped with an independent electrical control cabinet, which separates the low-voltage control circuit and the high-voltage power circuit to avoid electromagnetic interference. The power supply circuit is equipped with a main air switch, fuse, and surge protector to achieve overload, short circuit, and surge protection. A dual-circuit emergency stop button is set up to enable the entire system to stop quickly in an emergency. The normally closed emergency stop contact is connected to the PLC's safety input circuit and the contactor control circuit.

[0067] 2. Implementation of PLC control program In this embodiment, a modular pre-zeroing full-process automated control program was written in Siemens STEP 7-Micro / WIN SMART programming software. The core program modules are as follows: 2.1 Initialize the program module: After the system is powered on, it automatically performs initialization, resetting and configuring the PLC internal registers, RS232 communication parameters, IO port initial states, and resolver decoding module, clearing the fault register and position data register, confirming that all contactors are in the open state, and the system enters safe standby mode.

[0068] 2.2 Parameter Setting and Recipe Management Module: This module allows operators to manually set pre-adjustment zero parameters via a human-machine interface. It also includes a built-in storage function for pre-adjustment zero-adjustment process recipes for multiple motor models. These recipes include target current ratios, forward and reverse control timing, zero-position deviation thresholds, lock-up stabilization duration, and protection parameters. One-click recall, modification, and saving of recipes are supported. In this embodiment, for the 80kW main drive motor, the pre-stored standard recipe parameters are: U-phase target current +100A, V-phase target current -50A, W-phase target current -50A, V-phase target current +50A in fine-tuning mode, zero-position deviation threshold ±0.5° mechanical angle, lock-up stabilization judgment duration 300ms, overload protection threshold 130A, and maximum single energization duration 5s.

[0069] 2.3 Communication and Interaction Program Module: A communication subroutine based on the Modbus RTU protocol is written to send current setting and start / stop control commands to the constant current source at a 100ms cycle. At the same time, it reads the actual output current, operating status and fault information of the constant current source in a loop, uploads the data to the human-machine interface for display, and transmits it synchronously to the closed-loop control and fault diagnosis module.

[0070] 2.4 Closed-loop control program module: This module is the core executable program of the system, which can realize the automated control of the entire process of pre-zeroing, including contactor on / off timing control, rotor forward and reverse drive and phase sequence switching, real-time rotor position calculation and deviation judgment, zero position latching and offset calculation, and circuit disconnection logic after calibration.

[0071] 2.5 Fault Diagnosis Program Module: This module runs in the background throughout the entire process and can monitor the communication status, constant current source output current, contactor contact feedback status, rotor position signal, and emergency stop circuit status in real time. It can identify 12 types of faults, including communication interruption, overcurrent and undercurrent, abnormal contact action, position signal loss, and emergency stop triggering. When a fault is triggered, the emergency stop logic is immediately executed, cutting off all IO outputs and constant current source outputs. At the same time, the fault code, fault cause, and handling instructions are displayed on the human-machine interface, and the on-site audible and visual alarms are triggered.

[0072] 2.6 Data Storage and Traceability Module: This module can automatically store the zero offset, process parameters, running time, and equipment status data of a single motor's pre-zero calibration. It supports connection to the production line's MES system via an Ethernet interface to achieve automatic uploading and full-process traceability of pre-zero calibration data.

[0073] 3. Specific pre-zeroing process Based on the above hardware and software configuration, a complete pre-adjustment zeroing operation was performed on a single 80kW permanent magnet synchronous motor, fully demonstrating the entire process of forward and reverse fine-tuning, zero-position determination, and calibration. The specific steps are as follows: 3.1 Preparation for pre-zeroing and parameter configuration The operator fixes the motor to be pre-adjusted to zero using a tooling fixture, connects the motor's three-phase terminals to the quick-connect interface of the system contactor output, and connects the motor's resolver signal line to the resolver decoding module, completing the hardware wiring and clamping.

[0074] In the human-machine interface, select the pre-zero adjustment formula for "80kW main drive motor". The PLC will automatically load the corresponding pre-zero adjustment parameters and complete the parameter validity verification, and then indicate that the system is ready.

[0075] 3.2 System Startup and Self-Test When the operator triggers the "Start Pre-zeroing" button on the generated interface, the PLC immediately performs a full system self-test. 3.2.1 Verify that the RS232 communication with the constant current source is normal, read the operating status of the constant current source, and confirm that there is no fault; 3.2.2 Check the feedback from the auxiliary contacts of the contactor to confirm that all main circuits are in the open state; 3.2.3 Check if the resolver position signal is normal and read the rotor's initial position; 3.2.4 Confirm that the emergency stop circuit and safety door circuit are normal.

[0076] After all self-tests pass, the PLC sends the preset initial current parameters (U+100A, V-50A, W-50A) to the constant current source via RS232 communication. After receiving the parameters, the constant current source returns a "ready" signal.

[0077] 3.3 Initial forward drive, rotor moves closer to zero position The PLC outputs high-level signals to Q0.0, Q0.1, and Q0.2, energizing the coils of relays KM1, KM2, and KM3, closing their contacts, and driving the corresponding KM1 main, KM2 main, and KM3 main contactor coils to close synchronously, thus fully connecting the power supply circuit of the constant current source and the three-phase windings of the motor.

[0078] The constant current source outputs a stable DC current according to preset parameters. The combined magnetomotive force generated by the three-phase windings of the stator is precisely aligned with the theoretical d-axis electrical zero position (the position where the N pole of the rotor permanent magnet coincides with the U-phase axis of the stator). Driven by the electromagnetic torque, the rotor rotates in the positive direction toward the theoretical zero position.

[0079] During this process, the PLC acquires the rotor's original mechanical angle in real time through the resolver decoding module and simultaneously calculates the real-time deviation from the theoretical zero position. At the same time, it reads the actual output current of the constant current source in real time through communication. If a current deviation occurs, it immediately issues a correction command to ensure the accuracy of the current output and realize current closed-loop control.

[0080] In this embodiment, the initial position of the motor rotor is the original resolver angle of 126.2° mechanical angle, which deviates from the theoretical zero position by 126.2°. Under the drive of electromagnetic torque, the rotor rotates rapidly toward the zero position in the positive direction.

[0081] 4. Position overshoot detection triggers reverse fine-tuning After the rotor rotates forward for 2 seconds, the original mechanical angle collected in real time by the resolver is 1.2°. The PLC calculates that the current deviation from the theoretical zero position is +1.2° mechanical angle, which exceeds the ±0.5° deviation threshold preset by the formula. It is determined that the rotor has overshooted in the forward direction and immediately starts the reverse fine-tuning program.

[0082] The PLC performs the following synchronous actions: 4.1 Outputting a low level to Q0.1 disconnects relay KM2, causing the corresponding KM2 main contactor to disconnect and cut off the V-phase -50A current loop; 4.2 Outputting a high level to Q0.3 activates the fine-tuning relay KM4, closing the corresponding KM4 main contactor and switching the V-phase current loop to +50A output; 4.3 Simultaneously, fine-tuning current parameters (U+100A, V+50A, W-50A) are sent to the constant current source via RS232 communication to adjust the direction of the stator's synthesized magnetomotive force and drive the rotor to rotate in the opposite direction.

[0083] The constant current source outputs a stable current according to the new parameters, and the rotor begins to rotate slowly in the opposite direction, moving closer to the theoretical zero position. The PLC continuously monitors the rotor position changes in real time.

[0084] 5. Upon reaching the zero threshold, perform a lock-up stability check. After the rotor rotates in the reverse direction for 800ms, the original mechanical angle output by the resolver is 0.2°. The PLC calculates that the current deviation from the theoretical zero position is +0.2° mechanical angle, which has entered the zero position deviation threshold range of ±0.5°.

[0085] At this time, the PLC does not immediately perform calibration, but instead starts the 300ms lock-up stabilization timer preset by the recipe to continuously monitor the rotor position and the constant current source output status: 5.1 Within a 300ms timing period, the original rotor angle acquired by the resolver remained stable between 0.18° and 0.22°, with the position fluctuation amplitude being much smaller than the deviation threshold; 5.2 Synchronously monitor the actual output current of the constant current source. The U phase is stable at 100A±0.2%, the V phase is stable at +50A±0.3%, the W phase is stable at -50A±0.3%, and the zero-locking torque remains stable. After the timing ended, the PLC made a comprehensive judgment: the rotor had completely overcome external resistances such as cogging torque and frictional resistance, and was accurately and stably locked near the theoretical d-axis electrical zero position.

[0086] 6. Latch angle to complete core calibration. After confirming that the rotor is stably locked, the PLC immediately performs latching and calibration actions: 6.1 Precisely latches the original mechanical angle of the resolver output at the current moment: 0.2°; 6.2 Automatically calculate the specific zero-position offset of this motor: 6.2.1 Mechanical angle offset Offset_mech = Theoretical zero reference 0° - Latched original angle 0.2° = -0.2°; 6.2.2 Electrical angular offset Offset_ele = -0.2° × number of pole pairs 4 = -0.8°; 6.3 The offset, motor number, pre-zeroing parameters, and operation time are automatically stored in the PLC's data register to complete the pre-zeroing core calibration.

[0087] 7. Loop disconnection and process termination After calibration, the PLC immediately executes the closing action: 7.1 Output a low level to all digital output terminals, disconnect all relays, and disconnect all main contacts of the corresponding AC contactors, completely cutting off the power supply circuit between the constant current source and the motor; 7.2 Send a stop output command to the constant current source to turn off the power output of the constant current source; 7.3 The human-machine interface displays "Pre-zeroing complete" and simultaneously displays the calibrated zero offset data, prompting the operator to replace the next motor; 7.4 Automatically upload all data from this pre-zeroing to the production line management system to complete production data traceability.

[0088] It is worth noting that throughout the entire process described above, the fault diagnosis program runs in the background. If any abnormality occurs, it will immediately trigger an emergency shutdown and alarm to ensure the safety of the equipment, motors, and operators.

[0089] Experiments have verified that, using the system and method of this invention, the pre-zero adjustment cycle time of a single motor is ≤8s, and the pre-zero adjustment calibration accuracy can reach within ±0.1° mechanical angle, which is far higher than the industry's conventional mass production standard of ±1° electrical angle.

[0090] Moreover, for the same model of motor, the process formula can be called with one click, without the need to adjust the hardware and program. The entire process is automated and no manual intervention is required in the intermediate links. Not only is the first pass rate ≥99.9%, but the changeover time (including the time for disassembling the zeroed motor and reinstalling the motor that needs to be pre-zeroed) is also greatly reduced. This completely solves the industry pain points of insufficient precision, poor versatility, low efficiency and weak reliability of the existing technology, and perfectly adapts to the needs of large-scale and flexible mass production of new energy motors.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A system for pre-zeroing the rotor of a new energy vehicle motor, characterized in that, It includes a PLC logic control unit, a relay isolation drive unit, an AC contactor execution unit, a high-precision adjustable constant current source unit, and a rotor position detection unit; The digital output terminal of the PLC logic control unit is electrically connected to the control input terminal of the relay isolation drive unit. The PLC logic control unit establishes a bidirectional communication connection with the high-precision adjustable constant current source unit through a serial communication interface. The signal input terminal of the PLC logic control unit is connected to the rotor position detection unit. The output contacts of the relay isolation drive unit are connected to the coil control circuit of the AC contactor actuator unit, enabling the relay isolation drive unit to control the on / off state of the AC contactor according to the IO signals of the PLC logic control unit. The main contacts of the AC contactor actuator are connected in series between the high-precision adjustable constant current source unit and the three-phase power supply circuit of the new energy motor to be pre-adjusted to zero, and are used to control the on / off of the power supply circuit and the switching of the energizing phase sequence. The power output terminal of the high-precision adjustable constant current source unit is connected to the three-phase winding terminals of the new energy motor that requires pre-zeroing via an AC contactor, in order to provide the motor with the stable DC excitation current required for pre-zeroing.

2. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 1, characterized in that, The high-precision adjustable constant current source unit communicates with the PLC logic control unit through the RS232 serial communication interface. It is used to receive current control commands issued by the PLC logic control unit and to transmit the actual output current value, equipment operating status and fault alarm information back to the PLC logic control unit in real time. The high-precision adjustable constant current source unit is a DC constant current source that is continuously adjustable from 0 to 120A, with a current control accuracy of ≤ ±0.5%FS, and supports independent ratio adjustment of the three-phase output current.

3. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 1, characterized in that, The relay isolation drive unit includes multiple sets of relays. The coil input terminal of a single relay is electrically connected to the digital output terminal of the corresponding PLC logic control unit. The normally open output contacts of the relays are connected in series to the coil power supply circuit of the corresponding AC contactor.

4. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 1, characterized in that, The AC contactor execution unit includes multiple sets of AC contactors. Each set of contactors corresponds to the power supply circuit of one phase winding of the motor. The multiple sets of contactors correspond one-to-one with relays, so that the PLC logic control unit can drive the on / off combination of the corresponding contactors by controlling the on / off timing of different relays, thereby switching the energizing phase sequence of the constant current source and the three-phase winding of the motor.

5. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 1, characterized in that, The PLC logic control unit has a built-in pre-zeroing full-process automated control program, which includes an initialization program module, a parameter setting program module, a communication interaction program module, a closed-loop control program module, and a fault diagnosis program module. The initialization program module is used to initialize and reset the PLC's internal registers, communication parameters, and IO port status after the system for pre-zeroing the rotor of the new energy vehicle motor is powered on, ensuring that the system is in a safe standby state after power-on. The parameter setting program module is used to receive and store the pre-adjustment zero parameters input by the operator; The communication interaction program module is used to realize the control command issuance and status data feedback processing between the PLC and the constant current source; The closed-loop control program module is used to execute the entire process logic of relay and contactor on / off control, rotor forward and reverse rotation drive, zero position deviation judgment, and lock-up calibration based on the pre-adjustment zero parameters and rotor position real-time feedback signals. The fault diagnosis program module is used to monitor the system's full-dimensional operating status in real time, and execute emergency shutdown logic and trigger alarms when a fault is triggered.

6. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 5, characterized in that, The parameter setting program module supports the storage and one-click recall of pre-zero adjustment process recipes for multiple motor models. The pre-zero adjustment process recipes include target current ratio parameters, forward and reverse control timing, zero position deviation threshold, lock-up stability judgment duration, and protection parameters.

7. The system for pre-zeroing the rotor of a new energy vehicle motor according to claim 1, characterized in that, The PLC logic control unit has a built-in data storage and traceability module, which is used to automatically store the zero offset of the pre-zero calibration of a single motor, process parameters, equipment operation data, and fault information, and supports docking with the production line management system to realize data upload and full-process traceability.

8. A method for pre-zeroing a new energy rotor, characterized in that, The system for pre-zeroing the rotor of a new energy vehicle motor, as described in any one of claims 1-7, includes the following steps: S1) Connect the three-phase windings of the new energy motor that needs to be pre-zeroed to the output terminal of the AC contactor, and connect the signal output terminal of the motor's rotary transformer to the rotor position detection unit. S2) Select the pre-zero adjustment process formula for the corresponding motor model through the human-machine interface, or manually set the pre-zero adjustment parameters; S3) The PLC sends a pre-adjustment zero current control command to the high-precision adjustable constant current source; S4) The PLC outputs IO signals to control the corresponding relays and contactors to close, thus connecting the power supply circuit of the constant current source and the motor. The constant current source outputs a preset DC current to drive the motor rotor to rotate. At the same time, the PLC collects the rotor position signal in real time through the rotor position detection unit, continuously monitors the deviation between the rotor and the theoretical d-axis zero position, and controls the rotor to rotate forward or reverse for fine adjustment by switching the contactor on / off combination until the PLC determines that the rotor has reached the theoretical d-axis electrical zero position. S5) Latch the real-time output angle of the rotary transformer and automatically calculate and store the rotor zero-position offset.

9. The new energy rotor pre-zeroing method according to claim 8, characterized in that, In step S4), the specific rules for the PLC to determine that the rotor has reached the theoretical d-axis electrical zero position include: The PLC calculates the deviation between the current rotor position and the theoretical d-axis zero position in real time. When the deviation value enters the preset zero position deviation threshold range, the lock-up stabilization timer is started. If the rotor position fluctuation amplitude continues to be within the preset zero position deviation threshold range within the preset lock-up stabilization judgment time, it is determined that the rotor has been stably locked at the theoretical d-axis electrical zero position.

10. The new energy rotor pre-zeroing method according to claim 8, characterized in that, Throughout the entire process from steps S1) to S5), the fault diagnosis program preset in the PLC logic control unit monitors the system's operating status in real time. When communication interruption, abnormal current, abnormal device operation, abnormal rotor position, or emergency stop triggering fault is detected, the preset automatic emergency stop processing scheme is immediately executed, cutting off all relay outputs and constant current source outputs, while triggering on-site alarms and outputting fault location information.

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