变压器寄生参数和负载特性对高压脉冲波形的影响

Influence of transformer’s parasitic parameters and load characteristics on high-voltage pulse waveform

构建了输出电压幅值为0~20 kV、脉冲重复频率为0.25~20 kHz的双极性高压脉冲电源实验平台,研究了变压器寄生参数与负载特性对输出脉冲波形的影响。采用等效电路复频域解析方法,分析了变压器寄生参数对输出脉冲波形的上升沿、平顶及下降沿的影响规律,并通过改变变压器绕线方案间接验证。发现变压器分布电容和漏感越大,输出脉冲波形上升沿与下降沿越平缓,过冲电压幅值越大,并采用脉冲变压器二次侧均匀密绕、一次侧均匀疏绕、高匝数的方案进行优化。进一步分析了纯阻性、阻容性或阻感性负载特性对输出高压脉冲波形的影响规律,发现电阻值增大(5~50 kΩ),过冲电压幅值增大,脉冲上升沿和下降沿变陡;当负载电阻回路串联小电容时,过冲电压幅值显著增大,而电容值高于一定值时输出脉冲波形恢复至与纯电阻波形一样;当负载电阻回路串联电感时,输出脉冲波形下降沿变平缓。

The experimental platform of bipolar high-voltage pulse power supply with an output voltage amplitude of 0-20 kV and pulse repetition rate of 0.25-20 kHz is constructed. The influence of parasitic parameters of the pulse transformer and load characteristics on the output pulse waveform is studied. By the complex frequency domain analysis method, the effects of parasitic parameters of the transformer on the rising edge, flat top, and falling edge of the output pulse wave are analyzed theoretically, which are further indirectly verified by changing the winding scheme of the transformer. It is found that the larger the distributed capacitance and leakage inductance of the transformer are, the longer the rising time and falling time of the voltage pulse are, and the larger the overshoot voltage is. An optimization winding scheme of the pulse transformer is proposed in that the secondary winding is evenly and densely wound, the primary winding is evenly and loosely wound, and the number of turns is as high as possible.Furthermore, the influence of load characteristics on the output high-voltage pulse waveform is analyzed.(1) When the resistance increases(5-50 kΩ), the overshoot voltage increases, and the rising time and falling time of the voltage pulse decreases.(2) When a resistor is connected in series with small capacitors, the overshoot voltage increases significantly. If the capacitance is higher than a certain value, the output pulse waveform will be the same as that in the case of a pure resistor.(3) When a resistor is connected in series with an inductor, the falling time of the voltage pulse becomes longer.