一种实用化的交流斩波PWM控制时序研究

Practical Application of the AC Chopping PWM Control Timing

针对交流斩波电路容易产生短路,电压过冲和过电流等问题,提出一种基于交流电压和交流电流过零检测的交流斩波控制方法.通过对不同性质负载的电压和电流的相位研究,使用对电压和电流过零信号进行滤波,调相和逻辑运算后使能交流斩波的方法,避开过零点附近振荡过零区域,避免主电路产生短路.通过对斩波电路拓扑和控制时序的研究,使用逐渐改变PWM控制信号占空比的方法,实现电压软过度.通过实验检测,交流斩波调压电路实现了电压软过度的目的,并且不再出现短路,电压过冲和过电流现象.使用这种方法,从本质上解决了传统交流斩波电路中的短路,电压过冲和过电流现象,保证了交流斩波系统安全持久运行.

Short circuit,voltage overshoot and over current are liable to happen in an AC chopper.To solve these problems,an AC chopping PWM control method based on the AC voltage and AC current zero-crossing detection is proposed.Based on the analysis of the voltage and current phase of different loads,the method of voltage and current zero crossing signal filterring,phase modulation and logical operations which can realize AC chopping is used to keep away from the zero-crossing oscillations near the zero area,avoiding short circuit happening in the main circuit.Based on the study of the AC chopper topology and sequence control,the method for gradually changing the duty cycle of PWM control signal is used to achieve soft excessive,avoiding over shoot and over current happening in the main circuit.Through the experimental detection,the AC chopper realized voltage soft excessive with no short circuit,voltage overshoot and over current.By using this method,the traditional problems——AC chopper short circuit,voltage overshoot and over current can be solved essentially,ensuring AC chopping system＇s security and lasting operation.