Three Phase PMSM Control System Of Home Appliances

In recent years, variable frequency and energy-saving are drawing attention in the field of household appliances. The low efficiency single-phase asynchronous machines using in traditional home appliances cannot realize complex speed control, have been unable to meet the needs of modern people, nor respond to the call of improving resource utilization. Permanent magnet synchronous motor has a number of advantages such as small size and high efficiency. Thanks to the developments of motor control theory and power devices, some complex and precise speed and torque control have been conducted by permanent magnet motor fed by inverter. Using permanent magnet synchronous motor in household appliances is a promising research direction. This topic divides into two parts, the design of permanent magnet synchronous motor and the design of control system. This paper mainly studies the control system of permanent magnet synchronous motor used in household appliances.In this paper, a research of using three-phase permanent magnet synchronous motor control system in household appliances is conducted. Detailed discussions and descriptions are held about direct torque control after the presentation of PMSM common control strategies. A permanent magnet synchronous motor control scheme applied to household appliances is given. In this scheme, the traditional stator flux setting of constant in direct torque control is replaced by a dynamic one. The condition of maximum torque per ampere is achieved in PMSM where the stator current is reduced effectively and the motor efficiency is improved. As for sensorless operation, the motor speed is also estimated in this scheme.Both direct torque control and maximum torque per ampere direct torque control of a permanent magnet synchronous motor are modeled with MATLAB/Simulink. Simulations are conducted to observe the curves of speed response, current value, stator flux and electromagnetic torque. Results show that maximum torque per ampere direct torque control retains the feature of quick torque response in direct torque control. The torque response time is about 1ms. Stator currents are optimized as id=0 is basically achieved during the processes of changing load torque and speed signals. The speed is estimated with small errors. The proposed scheme is proved feasible and can be used as a reference when studying the application of PMSM in home appliances.