双极性脉冲电源的平衡变压器技术

Balun Technology for Bipolar Pulsed Power Supply

北京正负电子对撞机重大改造工程(BEPCⅡ)采用的是新型冲击磁铁Slotted Pipe Kicker,其结构上要求双极性供电．平衡变压器是实现双极性的关键部件,是解决脉冲源闸流管阴极可直接接地的绝好技术途径．平衡变压器是一种具有特殊用途的高压快脉冲变压器,因此其设计除了要解决高压快脉冲变压器的一般性技术问题外,还必须着重考虑电流平衡度指标．通过理论分析、模拟计算和测试实验证明不平衡电流主要由变压器的励磁电流和磁芯涡流损耗等效电流两部分组成．平衡变压器磁芯材料和几何尺寸选取,以及原副边导体结构设计是实现设计指标的关键所在．样机测试结果与设计计算结果相符,验证了平衡变压器设计理论的正确性,且平衡度D＜1%达到预定指标．

A new type slotted pipe kicker with advantage of low coupling impedance is adopted for the major upgrading of the Beijing Electron Positron Collider （BEPC Ⅱ ）. A bipolar pulsed power supply is needed for the new type kicker. In order to avoid difficulties caused by the fioating-thyratron scheme, a balun is introduced into the LC series resonance circuit with a grounded thyratron. The current balance degree between primary and secondary coils must be considered for the balun as a high-voltage fast-pulsed transformer for the special purpose. The unbalanced currents include magnetizing current and equivalent current of eddy-current loss in core. A nanocrystalline tape-wound toroid annealed in transverse magnetic field is chosen for the balun. To reduce leakage inductance, a simply parallel fiat structure is adopted in design of transformer primary and secondary conductors. The test results on the prototype confirm the design theory and current balance degree of the balun reaches the design target of D 〈1%.