采用三闭环控制的超低频高压电源设计

为了满足交联聚乙烯(XLPE)电缆对检测电源的要求,设计了一种采用两个高频高压变压器作为升压变压器的超低频高压电源。详细阐述了系统的硬件设计及软件控制策略,优化了变压器的结构及绝缘,大大缩小了变压器的体积及质量,减小了变压器的分布参数。并根据电路拓扑的特点,首次采用先进的三闭环控制技术,动态地对高频部分及低频部分的输出进行了监控与调整,减小了高频高压变压器分布参数对电源性能的影响。同时对采样数据采取了分段化的处理方法,大大减小了程序的计算量,使它能够应用于单片机控制。采用所设计的35kV/0.1Hz电源对电气特性等效于XLPE电缆的高压电容(1.5μF)进行了实验,其总谐波畸变率(THD)为2.76%,完全满足IEEE 400.2标准对总谐波畸变率<5%的要求。实验结果验证了理论的可行性与正确性。

Design of Very Low Frequency High Voltage Generator Using Three-closed-loop Control

A novel topology and the control strategy of the very-low-frequency(VLF) high voltage generator are introduced to meet the requirements of XLPE cable test.Design parameters of the system hardware and the control strategy of the system software are presented.The structure and the insulation of the transformer are optimized.As a result,the volume and the weight are decreased obviously.According to the topology of the circuit,the cutting edge of three-closed-loop control technology is first applied in VLF high voltage power supply.The output voltage and the secondary voltage are timely monitored and regulated,so that the influence of distributed parameter is reduced effectively.Simultaneously,the principle of segmental data processing is applied in data processing.Thereby,the calculation complexity is decreased significantly.The 35 kV/0.1 Hz power supply is used to test a 1.5 μF capacitor.Total harmonic distortion is 2.76% which can meet the requirements of IEEE 400.6 standard.The experimental results verify the accuracy and feasibility of the theory.