中文摘要：

大型永磁同步电动机（PMSM）对拖做负载试验时，由于作为发电机运行的PMSM端电压随负载电流增加而降低，端电压低于负载回馈的电网侧电压导致无法继续加载的问题，本文提出永磁同步发电机输出端并联电容器的方法，以补偿因电机感性回路中滞后的无功电流导致的发电机端电压下降。根据发电机定子绕组电流计算直轴去磁电流Id，定量计算无功补偿的电容值，既可以满足PMSM加载的需求，也可以避免投入电容量过大导致发电机端电压过高对电机绝缘材料寿命的影响；建立了带电容补偿的PMSM对拖测试的仿真模型。仿真结果表明，电容补偿值计算正确，能有效升高发电机的端电压，实现PMSM的平稳加载。与其它加载方法相比，该方法工程造价低，并能够实际应用于PMSM的性能测试。

英文摘要：

As the terminal voltage of permanent magnet synchronous motor（PMSM） running as the generator decreases with the load current increasing during the large permanent magnet synchronous motor back-to- back connected dragging for the load test, it will not be able to be loaded when the terminal voltage is lower than the grid-side voltage under the load feedback. In this paper, proposed an approach to make sure the capacitor and the output of permanent magnet synchronous generator were in paralleled, so the voltage reduction of the generator resulted from compensated. It can satisfy the need of 1 the lag of reactive current in the motor perceptual loop can be oading and the lifetime of generator insulation material would not be influenced by the overtopped terminal voltage of generator in the case of large capacitance after the direct axis current demagnetization I~ was calculated based on stator winding current of the generator and the capacitance reactive compensation was figured up, then simulation model of PMSM dragging test with capacitance com- pensation can be built. The simulation results show that the calculation of capacitance compensation is correct, so the terminal voltage of generator can be improved effectively, and the PMSM can be loaded steadily. The method in this paper has an advantage of low cost compared with other methods of loading, and can be used in the performance test of PMSM in practice.