数字式多相电流吸收负载研究

Research on the Digital-controlled Multi-phase Electronic Current Sink

设计了基于数字控制的多相电流吸收负载。从系统可靠性与灵活性方面考虑,系统采取了以宽安全工作区的线性MOSFET作为能耗元件,以数字控制回路代替传统的模拟回路的方案。调制模式采用多相交错PWM的方案进行主动式电流纹波抑制,克服了数字电力电子系统中有限开关频率与有限采样率的问题;在此基础上设计了功率电路与采样电路;并根据系统模型设计了可用于恒流与脉冲电流负载模式的数字控制器。样机采用dsPIC33FJ64GS606为主控芯片实现高精度四路交错PWM与实时控制;实验测试表明,该电流吸收负载具有较好的稳态、动态特性,可用于未来数字化的电源测试设备。

A digital-controlled multi-phase electronic current sink was proposed. For enhanced reliability and flexibility, a wide Safe Operation Area （SOA） MOSFET device was used as the power dissipating device; the control mode was not traditional analog control but digital control. Due to the inherent limitation of switching frequency and sampling rate in digital systems, interleaved multi-phase PWM scheme was proposed to provide active current ripple mitigation. Based on the system level analysis, the power stage and signal conditioning peripherals were designed and modeled; the digital controller was designed to provide regulation for constant current and pulsed current sink modes. The dsPIC33FJ64GS606 was used to provide four-phase interleaved high-precision PWM and real time control for the prototype. The experimental results indicate that the proposed system performs well in the steady-state and dynamic testing, and is applicable to the future digitalized testing equipment.