大电流恒流源系统的设计与实现

Design and application of constant current source system

针对断路器检测试验中对大电流恒流源系统的特殊要求,并为了能更准确、更方便、更可靠地检测断路器的使用性能,设计了一种基于多磁路变压器和PLC控制的大电流恒流源系统。该系统通过控制多磁路变压器输入端磁路的投入,使输出端获得全程分级连续可调的电压;系统采用反馈控制,通过电流互感器和PLC,输出电流和目标电流作负反馈比较,实现了"输出电流无限接近于目标电流且保持稳定",控制过程分为调零、内阻测量、多磁路投入、调压和稳流;根据系统的反馈控制策略,设计了三菱PLC的控制梯形图和上位机的软件程序;通过分别控制输入电压和试验内阻的变化,测试了系统的稳流性能。研究结果表明,该大电流恒流源系统使用界面友好方便、性能可靠、响应快、精度高。

Aiming at the special requirements of the constant current source for circuit breaker testing, and in order to detect the circuit breaker more accurately, more conveniently and more reliably, a system was designed based on the multi-magnetic transformer and PLC con- trol. The magnetic circuit input of the multi-magnetic transformer was controlled for getting continuously adjustable voltage. A feedback con- trol was used in the system, and through the current transformer and the PLC, the output current and the target current were compared and made infinitely close, and the control process was divided into zero adjustment, resistance measurement, multiple magnetic circuit input, voltage adjustment and current stability. According to the feedback control system, the control ladder diagram of Mitsubishi PLC and PC soft- ware program was designed. By controlling input voltage and resistance, the performance of currency stability was tested for the system. The results indicate that the system is reliable, fast response and high accuracy and the interface of the system is friendly and convenient.