Development On Module-Casacaded High-Voltage Pulse Generator

The Application of insulation is very extensive on power devices such as motors, transformers and capacitors. The insulation material determines power devices’ service life, the insulation material performance or power devices’ service life could be estimated and predicted by insulation aging test with high frequency, high voltage and high rise rate pulses. This paper mainly works on developing an insulation aging test pulse generator, to solve problems on high voltage, high rise rate and switching the output pulse polarity.The paper analyzed the benefits and drawbacks of some circuit topologies available in high-voltage pulse generator designs, and selected the cascaded inverters that DC sides are isolated, and AC sides works synchronously. The inverters output pulses directly to ensure high rise rate, and cascading makes high voltage. Power modules are driven synchronously to assure the inverters’ output rise together. Through different driving methods the pulses could be switched between unipolar and bipolar, to meet different testing requirements.According to the scheme, a high-voltage pulse generator was designed. The system includes a control board and a series of power modules. The control board takes TMS320F2812digital signal controller as the core. Through receiving the upper computer’s instructs, the control board adjusts the output voltage, and transmits the synchronal driving signal. The power modules are based on CPLD and MOSFET, to convert AC220V to pulses.The experiment results shows that the high-voltage pulse generator could output the predicted high voltage and high rise rate, and the pulse polarity can be switched. The pulse rise rate of the cascade system is almost the sum of every single module output rise rate. Some experiences in experiments were logged, the reasons that cause the out-sync effect of power modules and reduce the pulse rise rate when outputs are connected in series are also analyzed, and propel solutions were given. Through parameter measurements, the pulse generator meets the requirements.