基于虚拟电压矢量模型预测转矩的船舶推进电机控制研究

Research on marine propulsion motor control based on virtual voltage vector model to predict torque

针对船舶电力推进系统中六相永磁同步电机所采用传统直接转矩控制技术(DTC)仅采用最外围电压大矢量,会产生较大谐波电流并导致转矩波动大的问题,提出基于虚拟电压矢量合成的模型预测转矩控制策略(V-MPTC),利用α-β子空间中同向的大矢量和中矢量与z_(1)-z_(2)子空间中反向的小矢量和中矢量恰好对应原理,通过适当地调节一个PWM周期内大矢量和中矢量的占空比,可以使z_(1)-z_(2)子空间中的合成电压矢量幅值为0,实现对电机谐波电流和转矩脉动的抑制。同时为了便于硬件系统实现,进行电压矢量中心化以及采取提前2步的预测方法。仿真结果表明,采用V-MPTC控制策略使系统响应速度有所提高,启动转速超调降低,转矩脉动从0.15 N·m降至0.04 N·m,谐波畸变率从68.92%降至10.85%,验证了该方法在船舶电力推进系统中可提高其控制性能。

Aiming at the problem that the traditional direct torque control technology(DTC) of the six-phase permanent magnet synchronous motor in Marine electric propulsion system only employs the outermost voltage large vector,which will produce large harmonic current and lead to large torque fluctuation,a model predictive torque control strategy(VMPTC) based on virtual voltage vector synthesis is proposed.By using the principle that the large vector and medium vector in the same direction in the α-β subspace correspond to the small vector and medium vector in the z_1-z_(2) subspace in the opposite direction,the amplitude of the synthesized voltage vector in the z_1-z_(2) subspace can be 0 by adjusting the duty ratio of the large vector and medium vector in a PWM period,and the suppression of the harmonic current as well as torque ripple of the motor can be realized.At the same time,in order to facilitate the realization of the hardware system,the voltage vector centralization and the prediction method of two steps in advance are adopted.The simulation results show that the V-MPTC control strategy can improve the system response speed,suppress the start-up speed overdrive,reduce the torque ripple from0.15 N ·m to 0.04 N ·m,and decrease the harmonic distortion rate from 68.92% to 10.85%,which proves that the control performance of Marine electric propulsion system can be improved by this method.