基于PDC控制策略的APFC技术

分析了单相有源功率因数校正技术的原理及数字式控制现状,在此基础上提出了基于参考电流、电感电流、输入电压和参考电压的并联占空比控制的单相功率因数校正策略.改变了传统的电压电流双闭环控制策略.采用并联的电流闭环和电压闭环来控制输出电压和相位跟踪,传统占空比相应地被分为2个独立的电流占空比和电压占空比.在PSPICE环境下结合单相AC/DC拓扑进行了电路仿真,结果表明系统输入侧获得了单位功率因数,从而验证了控制策略的可行性.设计了单相AC/DC系统主电路和基于DSP的硬件控制电路,并采用C语言编程实现了单相AC/DC系统的功率因数校正功能.此外,考虑到电感电流的尖峰干扰等现象,采用了电感电流中点检测法使检测点远离开关噪声,保证了电感电流检测的准确性.仿真和实验结果基本一致,实现了系统输入侧的单位功率因数,并获得了期望的直流输出电压值.

APFC technology based on parallel duty cycle control strategy

The principle of single-phase APFC (Active Power Factor Correction) and its digital control technology are analyzed and the PDC(Parallel Duty Cycle) control strategy based on the reference current,inductive current, input voltage and reference voltage is developed for single-phase PFC. Instead of traditional nested close-loop control of voltage and current,the parallel close-loop control of current and voltage is applied to control the voltage output and phase tracking. Correspondingly,the traditional duty cycle is divided into independent current duty cycle and voltage duty cycle. Results of PSPICE-based simulation for single-phase AC / DC topology show that the unit power factor is achieved at input side, verifying the feasibility of control strategy. The main circuit of single-phase AC / DC system and the DSP-based control circuit are designed and the PFC function is programmed with C language. The mid-point detection method of inductive current is adopted to set the detection point apart from the switching noise point for avoiding the sharp-peak interference and ensuring the precise detection of inductance current. The experimental results show that,basically consistent with the simulative results,the unit power factor is realized at input side and the expected DC output achieved.