双频逆变器供电的感应电动机电磁转矩脉动控制

Electromagnetic torque ripple control of induction motor fed by dual frequency inverter

针对大功率场合下传统直接转矩控制转矩、磁链脉动大,开关频率不恒定等不足,研究了一种新的由双频逆变器供电空间矢量调制的直接转矩控制方案。在传统直接转矩控制的基础上,理论分析了直接转矩控制中磁链、转矩脉动的影响因素,推导出异步电机空间电压矢量数学模型,运用S-函数实现空间矢量调制。系统基于双频控制理论,采用级联逆变器供电降低系统的开关损耗。双频逆变器高频单元负责改善系统动态性能,低频单元传递主要功率。仿真结果表明:该方案不仅使系统具有较好的动静态性能,而且大幅度减小了电磁转矩、磁链脉动以及开关损耗,提高了的系统效率,适合于大中功率场合。

Direct torque control（DTC）of space vector modulation fed by dual frequency inverter is studied in order to solve the problems of large torque,big flux ripples and inconstant switching frequency of conventional DTC in large power occasions.On the basis of conventional DTC,factors affecting flux and torque ripples are analyzed and the space voltage vector mathematical model of induction motor is deduced,which is implemented by S-function.Based on dual frequency theory,the system is supplied by cascaded inverters to decrease losses.The high frequency unit is in charge of improving the dynamic performance of the system,whose switching current is relatively low;while the low frequency unit is in charge of energy delivery,whose switching frequency is far lower than that of the high frequency unit.The simulation results illustrate that by using this program,the system has a better performance in both dynamic and static performance,and the electromagnetic torque ripple,flux ripple and switching losses are significantly reduced.Thus the system efficiency is improved and suitable for medium and large power occasions.