双极性固态直线变压器驱动器的研制

在针对脉冲电磁场肿瘤消融的应用场合，双极性脉冲比单极性脉冲效果更均匀，而要产生ns级前沿的双极性高压纳秒或亚微秒脉冲难度大，电磁干扰强，控制要求更高。设计了一台双极性全固态直线型变压器驱动源(SSLTD)，双极性SSLTD由结构完全相同的LTD模块经过副边绕组反向串联构成，在负载上实现双极性窄脉冲。双极性SSLTD输出波形稳定的脉冲的关键在于磁芯复位，通过电阻负载实验，重点对比分析了复位电流的形式对复位效果的影响，以及采用直流复位时幅值、脉宽、正负脉冲时间间隔、单级模块中开关管并联数量、复位电流大小对双极性SSLTD输出的影响。实验结果表明，所设计的双极性SSLTD能够在500 Ω负载上稳定产生重频双极性纳秒脉冲，输出电压0～±5 kV可调，脉宽200～400 ns可调，正负脉冲时间间隔0～1 ms可调，上升沿和下降沿20～50 ns；反向串联的直流复位电路结构简单、复位效果好。该脉冲源使用模块化设计，结构紧凑，电气绝缘要求较低，可灵活输出双极性、正极性与负极性高压亚微秒脉冲。

Development of bipolar solid-state linear transformer driver

In the application of tumor ablation with pulsed electric field, bipolar pulses can ablate tumors more homogeneously than unipolar pulses. However, it is difficult to generate bipolar high voltage nanosecond or sub-microsecond pulses due to the strong electromagnetic interference and strict requirements of control precision. In this paper, a bipolar Solid-State Linear Transformer Driver (SSLTD) is designed. The SSLTD is composed of many LTD modules with the same structure and their secondary windings are reversely connected in series to generate bipolar narrow pulses over the load. To generate stable pulses, the reset of the pulsed transformers is the key technique in bipolar SSLTD. Through the resistive load experiments, the influence of the forms of reset current on the reset effect is compared and analyzed, and the influence of the voltage amplitude, pulse width, interval between positive and negative pulses, the number of parallel switches in each module, and the reset current amplitude on the output pulses is analyzed. Experimental results show that the designed bipolar SSLTD can generate repetitive bipolar nanosecond pulses with voltage amplitude up to 5 kV, adjustable pulse widths of 80−400 ns, the rising and falling 20−50 ns over 500 Ω load. Besides, reverse series DC reset circuit which is simple in structure has a better reset effect than pulsed reset circuit. The bipolar SSLTD can generate nanosecond pulses with any polarity and has many advantages such as compact size, modularity, low electric stress.