基于DSP的逆变点焊电源软开关PWM控制策略研究

Control strategy of PWM based on DSP for soft-switching spot welding inverter power

基于数字信号处理器(DSP)的软开关和控制技术已成为逆变焊接电源领域的研究热点。分析了零电压开关PWM逆变点焊电源和死区时间设置的工作原理,阐述了DSP比较单元的工作原理和利用DSP产生PWM方波的方法。利用C语言设计完成了DSP实现PWM信号输出与时序控制的软件。结果分析表明,移相PWM控制模式可保证逆变桥斜对角开关管错开关断,从而满足逆变点焊电源零电压开关的时间条件。对DSP相关寄存器赋值输出移相PWM方波以及符合要求的死区时间,实验证明,PWM方波可以满足零电压软开关逆变点焊电源逆变桥功率管的驱动时序要求。

Soft-switching technology and the control technology based on digital signal processor（DSP）are the most interested studying objects in welding inverter power source.In this paper, the working principle of the zero-voltage-switching pulse-width modulation （ZVS-PWM）for spot welding inverter power source and the principle of establishing dead-time are anlyzed,the operation principle of DSP＇s comparator and generating method of PWM square wave with DSP are introduced.Program is designed to produce the PWM signal and to complete the sequential control by use of C language.The analysis indicates that the phase-shifted PWM control pattern can guarantee the turning-off of diagonal switching devices of the full-bridge spot welding inverter at different time,which meets the time demand of zero-voltage-switching of spot welding inverter power source.The phase-shifted PWM square-wave and qualified dead-time are produced by assigning to DSP＇s relevant registers.The test results show that the PWM square-wave can meet drive time sequence demand of zero-voltage-switching for spot welding inverter power.