异步电机定子磁场定向弱磁区域最大转矩控制策略研究

Research on the Maximum Torque Control Strategy in the Field Weakening Region for Stator Flux Oriented Control of an Induction Motor

针对异步电机定子磁场定向的矢量控制系统在弱磁区域输出最大转矩的问题,提出一种新的磁通前馈的弱磁控制方法。该方法基于异步电机的Г型等效电路和定子磁场定向在弱磁区域运行的限制条件,分析了异步电机在弱磁区域运行时转矩和转差率的变化过程,根据转差率的变化规律将弱磁区域划分为两部分。证明了电机在第一个弱磁区域工作在电压极限和电流极限,在第二个弱磁区域工作在电压极限和转矩极限,同时证明在以上两个区域采用所提出的控制策略时输出的转矩为最大转矩,对应的磁通为最优磁通。实验结果证明了理论分析的正确性和所提出的的磁通前馈方法的有效性。

The induction motor should obtain its maximum output torque ability in the field weakening region when the stator flux oriented（SFO） control algorithm was adopted, and a new flux feedforward control strategy for the field weakening control method was proposed. The proposed strategy was based on the Г equivalent circuit of the induction motor and the restrictions of an SFO system in the field weakening region, also, it was based on the analysis of the variation laws of torque and slip. The field weakening region could be divided into two parts according to the change of the slip, and the motor works under the voltage and current limitations in the first region while it works under the voltage and torque limitations in the second region. It is proved that the output torque in the proposed strategy is the maximum, and the corresponding flux is the optimal. Experimental results prove the correctness of the above theory, and demonstrate that by using flux feedforward theme in the field weakening region, the maximum torque capability of the induction motor could be obtained.