Research On Direct Torque Control Strategy Of Permanent Magnet Synchronous Motor For HEV

In the case of the energy crisis and the increasingly serious environmental pollution, Hybrid electric vehicles is concerned by people due to the small energy consumption and low-emission characteristics of energy saving and environmental protection. Motor control technology is one of the core technologies of hybrid electric vehicles safe driving and accurate control of critical technology. So Hybrid electric vehicles control strategy and speed sensorless technology has become a research hotspot.In this paper, the research object is a permanent magnet synchronous motor used by hybrid electric vehicles. The direct torque control strategy is used to control the permanent magnet synchronous motor. Simulating and improving the strategy. The system model of sensorless control for PMSM of torque to current is established, which is based on model of reference adaptive system that use the reactive power as a speed estimation model.And simulations were carried out. The primary works of this paper are as follows:(1) The structure of the permanent magnet synchronous motor is analyzed. Common coordinate system of the permanent magnet synchronous motor control is introduced. Coordinate transformation principle is analyzed and the transformation matrix in different coordinate systems is derived. The mathematical model of permanent magnet synchronous motor in different coordinate systems is established.(2) Research the Permanent magnet synchronous motor control strategy, and build direct torque control simulink model of a permanent magnet synchronous motor and simulate it. Aimming at the problem of the larger ripple for torque and speed, combined real-time PI control and duty cycle control to improve the defects. Build the simulation model to simulation and compare with conventional control strategy.(3) Speed sensorless technology is introduced and the maximum ratio of torque to current control of direct torque control is used for hybrid electric vehicles. Aimming at the maximum ratio of torque to current control of direct torque control, the model reference adaptive controller using reactive power is designed. Build a simulation model to simulation, and the simulation results show that the estimation of speed can well follows the actual speed and the response time is short.the simulation results show that the control strategy has good dynamic and static performance in high-speed and low speed.