基于SVPWM的电动汽车直接转矩控制方法研究

Direct torque control system of electric vehicle based on SVPWM

针对传统直接转矩控制系统中存在较大转矩磁链脉动和开关频率不恒定等问题,对电动汽车用永磁同步电机的数学模型及其直接转矩控制方法进行了研究,提出了一种基于空间矢量脉宽调制技术(SVPWM)的直接转矩控制系统方案。该方案采用预期电压矢量计算单元取代传统直接转矩系统中滞环比较器,以得到能够减小当前定子磁链与转矩脉动的预期电压矢量,再利用SVPWM技术将预期电压矢量转换为实际电压矢量以实现对电机的控制。在Matlab/Simulink下构建了基于SVPWM的电动汽车直接转矩控制系统的仿真模型。仿真研究结果表明,该控制系统可以获得较小的转矩脉动和磁链脉动。

Aiming at the problems of torque pulsation and inconstant inverter switching frequency in the traditional direct torque control system, the mathematical model and the direct torque control method of permanent magnet synchronous motor were studied. A direct torque control system scheme based on space vector pulse width modulation （SVPWM） was presented to adopting the expected voltage vector calculation unit to replace the hysteresis comparator of conventional direct torque system, so that the expected voltage vector can reduce the current of stator flux and torque ripple would be obtained. In order to realize the motor control, the expected voltage vector was converted to the actual voltage vector by using the SVPWM technology. The simulation model of the direct torque control system based on the space vector modulation was built in the Matlab/Simulink. The simulation results indicate that the system can obtain small flux and torque pulsation.