CN-122026763-A - Multi-control strategy scheduling method and device for permanent magnet synchronous motor of electric tractor

CN122026763ACN 122026763 ACN122026763 ACN 122026763ACN-122026763-A

Abstract

The invention relates to a multi-control strategy scheduling method and device for a permanent magnet synchronous motor of an electric tractor, wherein the method comprises the steps of establishing a permanent magnet synchronous motor nonlinear model adapting to the operation characteristics of the electric tractor, introducing control simulation and real-time environment, establishing and integrating various differential motor control strategies based on the model to ensure that each strategy can independently operate, collecting mechanical and electromagnetic parameters of the motor, calculating nonlinear characteristic indexes, establishing a working condition characteristic parameter set after processing, establishing a fuzzy reasoning system taking load intensity, state change trend and electromagnetic nonlinear intensity as inputs and scheduling judgment quantity as outputs, and utilizing the system to infer working conditions, switching the control strategies, updating input variables in real time and circularly executing, thereby realizing dynamic self-adaptive adjustment of the control strategies along with the working conditions, further effectively improving the operation stability, control precision and energy efficiency of the permanent magnet synchronous motor and adapting to various working conditions and transitional state requirements of the electric tractor.

Inventors

WU SHUANGLONG
CHEN SHUBIN
QI LONG
YE XIAOXING
RAO JIAJUN
LIN CAIXIA

Assignees

华南农业大学

Dates

Publication Date: 20260512
Application Date: 20260225

Claims (10)

1. The multi-control strategy scheduling method for the permanent magnet synchronous motor of the electric tractor is characterized by comprising the following steps of: S1, establishing a permanent magnet synchronous motor nonlinear model for reflecting the low-speed high-torque operation characteristic of an electric tractor, and introducing the permanent magnet synchronous motor nonlinear model into a control system simulation and real-time control environment; S2, constructing a plurality of motor control strategies adapting to different operation characteristics according to control requirements of the electric tractor under different operation conditions and based on a nonlinear model of the permanent magnet synchronous motor, and carrying out functional division and parameter configuration on the plurality of motor control strategies to enable the different motor control strategies to form differentiation in response capacity, control precision or operation efficiency; S3, under different operation conditions, collecting mechanical parameters and electromagnetic parameters for reflecting the operation state of the permanent magnet synchronous motor, and calculating electromagnetic nonlinear characteristic indexes for reflecting the electromagnetic nonlinear degree of the motor based on the nonlinear model of the permanent magnet synchronous motor; S4, constructing a fuzzy reasoning system for identifying the operation condition of the electric tractor and controlling strategy scheduling, wherein the fuzzy reasoning system takes the operation load intensity, the operation state change trend and the electromagnetic nonlinear characteristic index as input variables and takes the control strategy scheduling judgment quantity as output variables; S5, based on the established fuzzy inference system, fuzzy inference is carried out by taking the running load intensity, the running state change trend and the electromagnetic nonlinear characteristic index corresponding to the current working condition as input variables, the control strategy scheduling judgment quantity output by the fuzzy inference system is obtained, the corresponding motor control strategy is switched according to the control strategy scheduling judgment quantity, state parameters reflecting the running state change are collected in real time, the input variables of the fuzzy inference system are updated, and the step is repeatedly carried out based on the updated input variables, so that the dynamic adjustment of the permanent magnet synchronous motor control strategy along with the working condition change is realized.
2. The method for dispatching the multi-control strategy of the permanent magnet synchronous motor of the electric tractor according to claim 1, wherein in the step S1, the nonlinear model of the permanent magnet synchronous motor comprises nonlinear mapping relations of magnetic linkage characteristics along with current change, inductance parameter characteristics along with working point change and electromagnetic torque, and the constructing steps of the nonlinear model of the permanent magnet synchronous motor are as follows: S11, establishing a geometric model for the permanent magnet synchronous motor according to the low-speed high-torque operation condition of the electric tractor, and carrying out finite element electromagnetic field analysis on the permanent magnet synchronous motor to obtain key electromagnetic parameters of the permanent magnet synchronous motor under different operation conditions, wherein the key electromagnetic parameters comprise flux linkage, electromagnetic torque, inductance and nonlinear variation characteristics of the flux linkage, the electromagnetic torque and the inductance; s12, performing model simplification and equivalent processing on the key electromagnetic parameters, constructing a permanent magnet synchronous motor nonlinear model capable of reflecting nonlinear characteristics of the permanent magnet synchronous motor, and guiding the constructed permanent magnet synchronous motor nonlinear model into a control system simulation and real-time control environment for replacing a traditional linear motor model in the control system simulation and real-time control environment; And S13, carrying out validity verification on a permanent magnet synchronous motor nonlinear model in an imported control system simulation and real-time control environment, comparing key electromagnetic parameters output by the model simulation with corresponding parameters obtained by a permanent magnet synchronous motor actual test, if the parameter error is within a preset precision threshold range, confirming that the permanent magnet synchronous motor nonlinear model is valid, and if the parameter error exceeds the preset precision threshold range, returning to the step S11 to re-optimize the geometric model or the finite element electromagnetic field analysis parameters until the constructed permanent magnet synchronous motor nonlinear model meets the precision requirement.
3. The method for dispatching the multi-control strategy of the permanent magnet synchronous motor of the electric tractor according to claim 2, wherein in step S2, according to the control requirements of the electric tractor under different operation conditions and based on a nonlinear model of the permanent magnet synchronous motor, a plurality of motor control strategies which comprise a magnetic field orientation control strategy and a direct torque control strategy and adapt to different operation characteristics are constructed, and the following functional division and parameter configuration are carried out aiming at the constructed plurality of motor control strategies, In the function division level, defining a magnetic field orientation control strategy as a steady-state efficiency priority control layer for minimizing torque pulsation and guaranteeing the operation efficiency of a system to be in a preset range; Aiming at a magnetic field directional control strategy, based on the nonlinear model of the permanent magnet synchronous motor, optimizing and configuring a proportional coefficient and an integral coefficient of a PI controller of a current loop and a speed loop in the magnetic field directional control strategy with the aim of minimizing steady-state errors, and aiming at a direct torque control strategy, dynamically configuring amplitude parameters of a torque hysteresis tolerance band and a magnetic linkage hysteresis tolerance band in the direct torque control strategy with the aim of maximizing a torque change rate and inhibiting strong nonlinear influences.
4. The method for dispatching the multiple control strategies of the permanent magnet synchronous motor of the electric tractor according to claim 3, wherein the specific process of the step S3 is as follows: S31, respectively acquiring operation state data corresponding to the permanent magnet synchronous motor according to different operation conditions of the electric tractor based on a constructed nonlinear model of the permanent magnet synchronous motor in a control system simulation and real-time control environment, wherein the operation state data comprises a permanent magnet flux linkage, a stator flux linkage, a d-axis inductance, a q-axis inductance, an electromagnetic torque, a stator current and a motor rotating speed; s32, defining an operation characteristic parameter vector containing mechanical operation states, electromagnetic nonlinear characteristics and dynamic change characteristics thereof based on the acquired operation state data, wherein the mechanical operation states comprise motor rotation speed, rotation speed change rate and electromagnetic torque; s33, carrying out normalization processing on the operation characteristic parameter vector, and simultaneously defining an electromagnetic nonlinear characteristic index based on the magnetic saturation characteristic of d/q axis inductance changing along with d axis current and the cross coupling characteristic of d axis flux linkage changing along with q axis current: S34, integrating the normalized operation characteristic parameter vector and the defined electromagnetic nonlinear characteristic index to construct a working condition characteristic parameter set for representing different operation working conditions and working condition transition states of the electric tractor.
5. The method for dispatching the multiple control strategies of the permanent magnet synchronous motor of the electric tractor according to claim 4, wherein the specific steps of the step S4 are as follows: S41, selecting a minimum complete input set containing operation load intensity, an operation state change trend and electromagnetic nonlinear characteristic indexes as controller input based on the working condition characteristic parameter set constructed in the step S3, and carrying out normalization processing on the minimum complete input set, wherein the operation load intensity comprises load/operation intensity; S42, defining a normalized minimum complete input set as an input fuzzy language set, wherein the input fuzzy language set is used for distinguishing the operation stage of the electric tractor, judging whether the electric tractor is in a working condition transition stage, reflecting the operation strength and the load level of the electric tractor and the degree of deviation of electromagnetic parameters of the permanent magnet synchronous motor from a linear model at the current operation point; S43, quantitatively describing the input fuzzy language set and the output fuzzy language set by adopting a triangle membership function, constructing fuzzy rules covering different operation conditions and transition states of the different operation conditions of the electric tractor according to the quantitative description, and carrying out self-adaptive judgment on the permanent magnet synchronous motor control strategy by the fuzzy rules; And S44, carrying out rule synthesis on output results of all fuzzy rules in the fuzzy rule reasoning process to form an output fuzzy set for reflecting comprehensive fit degree of different permanent magnet synchronous motor control strategies, and carrying out fuzzy decomposition processing on the output fuzzy set to obtain a control strategy scheduling judgment amount for motor control strategy selection, switching or cooperative control.
6. The method for dispatching the multiple control strategies of the permanent magnet synchronous motor of the electric tractor according to claim 5, wherein the specific steps of the step S5 are as follows: s51, based on a built fuzzy inference system, performing fuzzy inference by taking the running load intensity, the running state change trend and the electromagnetic nonlinear characteristic index corresponding to the current working condition as input variables to obtain a control strategy scheduling judgment amount; S53, introducing at least one of a time window smoothing, continuous judgment and hysteresis mechanism into the control strategy scheduling judgment quantity to determine whether the control strategy scheduling judgment quantity meets the executing condition of motor control strategy switching or cooperation, executing motor control strategy switching operation only when the control strategy scheduling judgment quantity continuously meets the switching condition in a preset continuous sampling period, and enabling the switching condition of the motor control strategy to be different from the returning condition by setting a hysteresis interval so as to avoid frequent switching in a working condition critical area; S54, controlling the permanent magnet synchronous motor based on the determined control strategy selection mode or the cooperation mode so as to realize stable operation under different operation working conditions and working condition transition states; And S55, collecting state parameters for reflecting the running state change in real time, updating the input variables of the fuzzy inference system, and repeatedly executing the steps S51-S55 based on the updated input variables to realize the dynamic adjustment of the permanent magnet synchronous motor control strategy along with the working condition change.
7. The multi-control strategy scheduling method for the permanent magnet synchronous motor of the electric tractor according to claim 6 is characterized in that in step S55, state parameters reflecting the current running state of the permanent magnet synchronous motor are collected in real time, wherein the state parameters comprise real-time stator three-phase current, current motor rotating speed and rotor position angle, in each control sampling period, electromagnetic torque, d/q axis flux linkage and inductance parameters of the current sampling period are obtained through real-time calculation of a nonlinear model of the permanent magnet synchronous motor based on the state parameters, according to the calculation result, running load intensity, running state change trend and electromagnetic nonlinear characteristic index of the current sampling period are recalculated and extracted, the calculation result is normalized and then used as an input variable updated by a fuzzy reasoning system, the fuzzy reasoning system is driven to enter the reasoning algorithm of the next control period based on the updated input variable, strategy scheduling judgment is repeatedly executed, and therefore closed loop monitoring is formed, and dynamic self-adaption adjustment of the permanent magnet synchronous motor control strategy along with the change of the working condition of the electric tractor is achieved.
8. The multi-control strategy scheduling device for the permanent magnet synchronous motor of the electric tractor is characterized by comprising the following steps of: The nonlinear modeling module is used for establishing a permanent magnet synchronous motor nonlinear model reflecting the low-speed high-torque operation characteristic of the electric tractor and introducing the permanent magnet synchronous motor nonlinear model into a control system simulation and real-time control environment; the multi-strategy construction module is used for constructing a plurality of motor control strategies adapting to different operation characteristics according to the control requirements of the electric tractor under different operation conditions and based on the nonlinear model of the permanent magnet synchronous motor, and carrying out functional division and parameter configuration on the plurality of motor control strategies so as to lead the different motor control strategies to form differentiation on response capacity, control precision or operation efficiency; The working condition feature extraction module is used for collecting mechanical parameters and electromagnetic parameters reflecting the running state of the permanent magnet synchronous motor under different running conditions, and calculating electromagnetic nonlinear feature indexes reflecting the electromagnetic nonlinear degree of the motor based on the nonlinear model of the permanent magnet synchronous motor; The fuzzy reasoning system module is used for constructing a fuzzy reasoning system for identifying the running condition of the electric tractor and controlling strategy scheduling, and the fuzzy reasoning system takes the running load intensity, the running state change trend and the electromagnetic nonlinear characteristic index as input variables and takes the control strategy scheduling judgment quantity as output variables; The dynamic scheduling execution module is used for carrying out fuzzy reasoning on the basis of the established fuzzy reasoning system, taking the running load intensity, the running state change trend and the electromagnetic nonlinear characteristic index corresponding to the current working condition as input variables to obtain a control strategy scheduling judgment amount output by the fuzzy reasoning system, switching the corresponding motor control strategy according to the control strategy scheduling judgment amount, collecting state parameters reflecting the running state change in real time, updating the input variables of the fuzzy reasoning system, and repeatedly executing scheduling reasoning on the basis of the updated input variables to realize the dynamic adjustment of the permanent magnet synchronous motor control strategy along with the working condition change.
9. An electronic device comprising a central processor and a memory, characterized in that the central processor is adapted to invoke a computer program stored in the memory for performing the steps of the electric tractor permanent magnet synchronous motor multi-control strategy scheduling method according to any of claims 1 to 7.
10. A computer readable storage medium, characterized in that it stores in the form of computer readable instructions a computer program implemented according to the electric tractor permanent magnet synchronous motor multi-control strategy scheduling method according to any one of claims 1 to 7, which when invoked by a computer to run, performs the steps comprised by the corresponding method.

Description

Multi-control strategy scheduling method and device for permanent magnet synchronous motor of electric tractor Technical Field The invention relates to the technical field of motor control, in particular to a method and a device for dispatching multiple control strategies of a permanent magnet synchronous motor of an electric tractor. Background As core equipment in modern agricultural production, the electric tractor is required to complete various operation tasks such as starting, site transition, field operation and the like, and the operation working condition has the characteristics of high complexity, frequent load fluctuation and large amplitude change, and strict requirements are put forward on the control performance and the energy efficiency level of a driving system. The permanent magnet synchronous motor has become a main flow power executing device of an electric tractor driving system by virtue of the remarkable advantages of high energy conversion efficiency, high power density, wide speed regulation range and high control precision, and directly determines the operation efficiency, the cruising ability and the running stability of the electric tractor. However, when the electric tractor works in the field, the electric tractor needs to be in a low-speed high-torque running state for a long time, and is frequently switched among working conditions such as starting, transferring and working, so that the control of the permanent magnet synchronous motor faces remarkable technical challenges that the control precision, the dynamic response and the steady-state energy efficiency are difficult to cooperate and compromise, and the improvement of the full-working-condition running performance of the electric tractor driving system is severely restricted. Currently, in the technical field of permanent magnet synchronous motor control of electric tractors, main stream control strategies mainly comprise two types of magnetic field directional control (FOC) and Direct Torque Control (DTC). In order to improve the control performance of a single control strategy in practical application, related researchers propose various self-adaptive parameter adjustment technologies, and the robustness of the single control strategy in the scenes of motor parameter drift, load burst disturbance and the like is improved to a certain extent by carrying out on-line optimization correction on core parameters in a controller, such as technical means based on self-adaptive PI parameter adjustment, disturbance observer parameter real-time correction, dead zone effect compensation and the like. However, such an improvement scheme still does not break through the inherent structural limitation of a single control strategy, the control logic of the control scheme is always unfolded around the single control mode, and in the complex and changeable operation working condition and the frequent transition process of the working condition of the electric tractor, the dynamic response speed, the steady-state control precision and the operation energy efficiency of the driving system are difficult to be simultaneously considered, so that the use requirements of the electric tractor on the high performance and the high reliability of the driving system under different operation scenes can not be met. Aiming at the problem of obvious control performance difference of the motor under different operation conditions, the prior art also provides a corresponding improvement thought, and the control strategy switching method mainly comprises two types, namely a control strategy switching method based on fixed threshold setting of rotating speed, torque and the like, and a mode of manually judging and selecting a control mode by a driver. However, the two methods have obvious defects in actual agricultural production application, namely, on one hand, a fixed threshold switching mode cannot accurately adapt to the change of nonlinear characteristics in the running process of an electric motor, and is difficult to accurately capture the dynamic change rule of a working condition transition stage, and on the other hand, the manual mode selection not only increases the operation complexity of a driver, but also relies on manual experience judgment on switching time, so that the method is high in subjectivity and low in accuracy, and is easy to cause the problems of control impact, torque fluctuation and the like in the working condition transition stage, thereby reducing the control performance of the electric motor, increasing the energy consumption and even affecting the operation stability and the safety of an electric tractor. In summary, when the existing control technology of the permanent magnet synchronous motor of the electric tractor is used for coping with complex and variable operation working conditions and working condition transition processes, technical bottlenecks such as poor adaptability of control strategies, difficult coopera