The High-speed And Low-carrie Ratio Control Of Power Driven Permanent Magnet Synchronous Motor

With the development of permanent magnet materials,the manufacturing technology level of permanent magnet synchronous motor has been significantly improved.Because of its small size,high power density,good reliability and other advantages,induction motor is gradually replaced in industrial applications.At the same time,driven by the development of power electronics technology,the digitalization of permanent magnet synchronous AC servo control system is developing rapidly.However,with the improvement of servo system power,the switching loss of the inverter becomes more and more serious which results in the switching frequency being limited.It is not conducive to the control performance of the motor.On the other hand,with the improvement of the manufacturing technology of permanent magnet synchronous motor,high-speed and ultra-high-speed motors are widely used in the servo industry.This will also reduce the ratio of the switching frequency of the inverter to the operating frequency of the motor.At this time,the output accuracy of the inverter will be reduced and the control performance will be worse.Therefore the current loop coupling effect,digital control delay and the influence of motor parameter change on control accuracy under low carrier ratio condition should be deeply analyzed to improve the performance of PMSM control system as a whole.Firstly,the mathematical model of permanent magnet synchronous motor in three coordinate systems is constructed in the continuous domain,and the complex vector model of the motor is deduced in the continuous domain.Finally,the discretization model of the motor is obtained based on the continuous domain motor model,which paves the way for the subsequent design of current regulation in the continuous domain and the discrete domain respectively.In this paper,a design method of continuous-domain current regulator based on integral feed-forward decoupling is proposed to solve the voltage coupling problem in embedded permanent magnet synchronous motor control.Compared with traditional feed-forward and feedback decoupling control,two adjustable decoupling parameters are introduced aiming at improving the decoupling accuracy and the integral feed-forward term also reduces the influence of current sampling error on decoupling.Aiming at the discrete error of current regulator and one-step time delay in digital control,a design method of digital current regulator considering one-step time delay is proposed,which avoids the discrete error and reduces the error caused by digital delay of regulator output voltage and improves the dynamic characteristics of current loop.In view of the sensitivity of the control system to the variation of motor parameters,an active damping control method based on predictive current is proposed,which increases the stator resistance of the motor equivalent and reduces the influence of current sampling error on the regulator.So it improves the robustness of the motor control system.Finally,by MATLAB/Simulink simulation and experiments based on the AVL experimental platform,high speed and low carrier ratio operation of permanent magnet synchronous motor is realized.By comparing the current regulator directly designed in the continuous domain with the current regulator directly designed in the discrete domain,the feasibility and advantages of the current regulator based on integral feedforward decoupling and the control strategy of digital current regulator with one-beat hysteresis are verified.