基于谐波补偿的交流恒流源复合控制策略及实现

Implementation of AC Constant Current Source Based on Harmonic Compensation and Compound Control Strategy

数字式交流恒流源是小型断路器数字化自动检测线的关键设备.考虑到断路器生产节拍和检测的一致性问题,断路器中交流恒流源需要具备输出电流长期稳定、响应速度快和精度高等特点,而目前市场上用在类似场合的交流恒流源不能满足上述要求.因此,采用基于谐波补偿算法和非线性整定的PID控制算法相结合的控制策略,设计了一款以ARM微控制器为核心的数字式交流恒流源,其硬件电路拓扑包含H桥式逆变器、LCR滤波器和升流变压器等.测试结果表明,所设计的数字交流恒流源最大输出电流为200 A,电流稳定误差≤±0.3%,总谐波失真度THD≤1%,并具有响应速度快、受电网电压波动及其他外界干扰因素影响小等特点,能满足断路器生产检测线的使用要求.

Digital AC constant current source is the key equipment of digital automatic detection line of miniature circuit breaker.Considering the production rhythm and detection consistency of circuit breaker,the output current of AC constant current source is required to maintain the characteristics of long-term stability,fast response speed and high accuracy.However,the AC constant current source used in similar occasions in the market can’t meet the above requirements.Therefore,a digital AC constant current source with ARM(Advanced RISC Machine,ARM)microcontroller as the core is designed.The software adopts the control strategy based on the combination of harmonic compensation algorithm and nonlinear self-tuning PID(Proportion Integration Differentiation,PID)control algorithm.The hardware circuit topology includes SPWM-2H bridge inverter,LCR filter and voltage regulator.The test results show that the maximum output current of digital AC constant current source is 200A,the current stability error is less than 0.3%,and the THD(Total Harmonic Distortion,THD)is less than 1%.It has the characteristics of fast response and little influence by power grid voltage fluctuation and external interference.It can meet the application requirements of the production and testing line of the circuit breaker.