异步电机直接转矩控制系统快速正反转控制策略研究

【作者】 汪少军；

【导师】 喻寿益；

【作者基本信息】 中南大学 ， 控制科学与工程， 2009， 硕士

【摘要】 在分析直接转矩控制工作原理的基础上,针对异步电机经典正反转实现方法存在过渡过程时间长、转矩脉动大、反向起动电流畸变严重等缺点,提出了异步电机直接转矩控制系统快速正反转控制策略,该控制策略利用转子磁链惯性作用,通过控制定、转子磁链位置角的相对关系,使电机输出制动转矩或电动转矩。当要求电机输出电动转矩时,控制定子磁链超前转子磁链旋转;当要求电机输出制动转矩时,控制转子磁链超前定子磁链旋转。通过Bang-Bang控制策略,使电机在正反转过渡过程阶段输出恒定的制动转矩和恒定的反向起动转矩。该控制策略能有效缩短正反转过渡过程时间,反向起动电流畸变小,转矩脉动小,过渡过程平滑,对传动机械装置无冲击,非常适用于要求传动电机经常正反转的生产过程。针对异步电机直接转矩控制系统低速时转矩脉动大的问题,设计了异步电机直接转矩预测控制策略。该控制策略通过计算在当前控制周期消除转矩误差电压空间矢量需要工作的时间,剩余时间施加零电压空间矢量的方法,降低转矩脉动量,减少电流畸变,改善电机的低速运行性能。基于MATLAB/Simulink平台分别对摩擦类和位能类恒转矩负载DTC系统正反转控制策略进行了仿真,并对传统控制方法与预测控制方法做了对比仿真研究。仿真结果表明提出的快速正反转控制策略可以使电机输出恒定制动转矩和恒定反向起动转矩,缩短异步电机正反转过渡过程时间,且在整个过渡过程中,定子电流在电机允许最大范围内。采用提出的预测控制策略,有效减小了直接转矩控制系统转矩脉动,改善了定子电流波形,提高了异步电机直接转矩控制系统的性能。最后,在37KW异步电机交流调速实验平台上对提出的快速正反转控制策略进行了实验,实验结果表明提出的正反转控制策略可实现电机快速、平滑正反转,验证了控制策略的有效性和可行性。更多还原

【Abstract】 At first, the direct torque control (DTC) theory is deeply analyzed in this paper. In order to solve the problem of long reversion interim, large torque ripple and serious distortion of motor’s stator current in the process of reversion stage, a control strategy is put forward to realize quick reversion function in induction motor DTC control system. Making use of rotor’s inertia, motor outputs driving torque and braking torque by controlling the relative angle position between stator flux and rotor flux. Motor outputs driving torque by keeping stator flux rotating ahead of rotor flux; motor outputs braking torque by keeping stator flux rotating behind of rotor flux. Motor outputs invariable braking torque and reversal start driving torque by bang-bang control strategy, which could shorten the reversion interim and no current distortion of motor’s stator at reversal start stage, also reduce torque ripple, without shock to transmission equipment. It is very applicable to production process which request motor’s frequent reversion rotate.Secondly, direct torque predictive control strategy is designed to solve the problems of large torque ripples in traditional IM DTC system. According to this control strategy, working time of voltage space vector in every control period is calculated which can eliminate the torque ripple, motor is given zero voltage space vector in the rest time of present period. The predictive control strategy can reduce torque ripple and stator current’s distortion effectively, improve motor’s low speed performance.At last, simulation models of the conventional and predictive DTC system which can realize motor’s reversion function are separately established based on the MATLAB/ Simulink platform. Simulation results prove that reversion control strategy can realize motor’s quick reversion function with invariable braking torque and reversal start braking torque, also shorten reversion interim without large stator current. Predictive control strategy can restraint torque ripple, reduce stator current’s distortion effectively. DTC quick reversion strategy is realized in 37KW IM AC speed regulation experiment platform, the process of reversion is finished slidely in a short time, the results prove the control strategy’s effectivity and feasibility.更多还原