Design Of Permanent Magnet Synchronous Motor Controller Based On FOC Algorithm

Permanent magnet synchronous motor(PMSM)has the advantages of large torque,high power density,high efficiency,and energy-saving,which is widely used in electric vehicles,variable frequency air conditioning,variable frequency washing machine,sweeping robot,and other fields.The design of the permanent magnet synchronous motor control system is a hot issue in academia and industry.The common control methods are constant voltage-frequency ratio control,field oriented control(FOC),and direct torque control.The FOC system has the advantages of high power density,high torque density,small torque pulsation,high controllability,and stable frequency conversion speed regulation,which meets the needs of practical motor applications.Therefore,the FOC system is often used in the control of permanent magnet synchronous motor.Because FOC systems need to obtain rotor position and speed information and mechanical sensor measurement costs are high and operating conditions are limited by the environment,the sensorless detection method has significant advantages over FOC systems.In this text,the traditional FOC algorithm is improved,and on this basis,a low-cost permanent magnet synchronous motor controller is proposed,which can be applied to scenarios where the rotor position resolution of the motor is not high but the cost is strict,such as household frequency conversion washing machine,frequency conversion air conditioning,etc.The improved FOC system abandoned the traditional Park coordinate transformation to decouple the current and simplified the double closed-loop control of speed and current loop into a single-speed loop control.The phase current was controlled as a sinusoidal wave by directly controlling the phase voltage.The output of the improved FOC system adopts the space vector pulse width modulation(SVPWM)algorithm,which generates PWM waves according to the combination of voltage vector and zero vector in time to control the switching states of the six MOSFET,and then provides three-phase sinusoidal alternating current to drive the motor.In addition,the system uses a sliding mode observer(SMO)to estimate the rotor position and speed in real-time,significantly reducing the cost compared to solutions using sensors.Firstly,the structure and mathematical model of permanent magnet synchronous motor are introduced,and then the control principle of the traditional FOC algorithm is described.On this basis,the system scheme of the improving FOC algorithm is proposed,and then the algorithm level simulation is carried out in MATLAB/Simulink environment.Then the hardware design of the whole system and module is completed with Verilog hardware description language,and the mode-level function simulation is carried out on Modelsim software.Finally,the FPGA hardware environment is built,and the control performance of the system scheme on the permanent magnet synchronous motor is actually tested.In this text,a low-cost controller for the permanent magnet synchronous motor is designed,which has the characteristics of simple structure and good performance.By reducing the number of PI controllers to one,eliminating the Park coordinate transformation and adopting the sensorless SMO approach,the system cost is significantly reduced.The experimental results show that the improved FOC system achieves a feedback accuracy of20 k Hz with a closed-loop operation time of 40.26μs,and the motor speed error is stable within 8%.The motor control system shows good control performance,the motor speed is stable,and meets the application needs of low-cost controller.