适用于变频电机绝缘测试的脉冲方波发生器

为合理评估变频电机绕组的绝缘性能,IEC建议采用脉冲方波电压开展测试并且选择合适的脉冲参数以减小电压波形带来的测试偏差。通过对脉冲电源波形参数选择的分析,研制了一台基于桥式固态开关器件的直接输出式脉冲方波电源,给出了脉冲变换主回路暂态参数的设计方法。波形测试结果表明该脉冲方波电源能够输出具有对称脉冲边沿特性的脉冲方波,通过控制半导体固态开关和调节充放电参数能得到最短脉冲边沿时间20 ns、最大重复频率20 kHz、最高电压幅值10 kV的对称脉冲波形,耐电晕寿命测试结果与相关研究结论一致。该脉冲电源运行可靠、结构简单,输出波形稳定,可用于开展脉冲电压条件下变频电机绝缘性能评估工作。

A Repetitive Impulsive Square Wave Voltage Generator Used for the Insulation Evaluation of Converter Motor

In order to evaluate the insulation performance of converter motor windings reasonably, the International Electrotechnical Commission (IEC) released two standards and recommended to evaluation the insulation by using repetitive impulsive voltage. The voltage parameters can significantly influence insulation lifetime, and thus, voltage parameters should be carefully controlled during the experiments. Firstly, the waveform parameters selection method is analyzed in this paper. Secondly, the development process of this generator is introduced in detail. Finally, this paper gives the calculation method of key parameters of pulse conversion main circuit. The measurement results show that this generator can output pulse square wave with symmetrical pulse edge characteristics. By controlling the semi-solid-state switch and adjusting the charge/ discharge parameters, a symmetrical pulse square wave with the shortest pulse edge time of 20 ns, the maximum continuous repetition frequency of 20 kHz and the maximum voltage amplitude of 10 kV can be obtained. This generator is reliable in operation, simple in structure and stable in output waveform. It can be used to evaluate the insulation performance of convertor motor under pulse voltage conditions.