Hybrid Electric Vehicle With Permanent Magnet Synchronous Motor Direct Torque Control

AC permanent magnet synchronous motor (Permanent Magnet Synchronous Motor, referred to as PMSM) is a kind of high performance motor, has the advantages of simple structure, reliable performance, high torque/weight ratio, good speed performance, small loss and such prominent advantages, gradually got the attention of people, especially favored in the occasion of high accuracy and high reliability.From Direct Torque Control technology (Direct Torque Control, referred to as the DTC) used in converter began, it has become a new period of frequency conversion technology leader. Direct torque control has the advantages of simple operation, fast dynamic response, the torque of system parameter perturbations and external disturbances has strong robustness, so it is widely applied in the control system of permanent magnet synchronous motor. But the existence of large torque pulsation, inverter switching frequency cannot remain stable, in the low rate is very difficult to control and other issues. In order to solve these problems, based on SVPWM direct torque control strategy is proposed, the use of space voltage vector torque ripple is weakened dramatically, but the PI controller itself has certain disadvantages.Sliding mode variable structure control have some advantages of fast response,model accuracy is not high, the safety of self-adaptability and robustness to parameter variations and load disturbance, the physical realization simple and so on, in the field of motor speed are widespread used. Fast terminal sliding mode variable structure control strategy to the introduction of permanent magnet synchronous motor direct torque control,based on Lyapunov stability theorem, to achieve the purposes that system state convergence in a finite time and reduce the static error, only adjust the controllerdesign parameters, system parameters and external disturbance shows strong robustness. To solve the problems existing in the traditional DTC.In order to cancel the permanent magnet synchronous motor speed control system of mechanical sensor, based on the Radial Basis Function (Radial Basis Function, hereinafter referred to as the RBF) neural sliding-mode observer of the nonlinear speed/position estimation method is put forward. Based on the mathematical model of the permanent magnet synchronous motor, the sliding surface form according to the error between measured current and observational current, using observed back EMF to calculate estimated speed/position. Sliding mode variable as the input of RBF neural network, the output of the network is the observer control strategy, control target from the tracking error to sliding mode function, because the neural sliding mode controller input is always the same dimension with the control input, simplifies the control structure of conventional neural network and reduces the chattering phenomenon of general sliding mode control, at the same time identified in the system is robust, in order to achieve a more accurate estimate of rotor position and speed, and verified the stability and effectiveness of this method.On the base of theory analysis, in the MATLAB/Simulink simulation platform to build a permanent magnet synchronous motor direct torque control system model for experimental analysis, the results showed that in the weake motor torque ripple, terminal sliding mode variable structure control algorithm is more excellent, but also can ensure the rapid response characteristics, changes of the system parameters and the load disturbance reflects the excellent robustness.