脉冲变极性弧焊逆变电源数字化控制系统

Digital control system for inverter-controlled arc welding power supply with pulsed variable polarity output

在采用数字信号处理器(DSP)DSP56F805构建基于双DSP的脉冲变极性弧焊逆变电源全数字化控制系统的基础上,针对数字化脉宽调制(PWM)控制脉冲存在的脉冲宽度保持和延迟对电源输出动态响应和稳态精度等控制性能的影响,提出了基于电源输出电感电阻(LR)负载模型的电流预估计算法,进而对简单数字比例积分微分(PID)控制算法进行了修正。同时,系统通过对电流/电压检测信号的预处理、A/D采样与PWM同步、数字滤波等措施有效地提高了系统的抗干扰性能。脉冲变极性输出特性控制试验验证了基于电流预估计的数字PID控制算法的正确性和有效性。

The full-digitized control system of inverter-controlled arc welding power supply with pulsed variable polarity output based on dual DSPs (digital signal processor) is developed by using DSP56F805. To overcome the influence of the pulse width holding and delaying existed in digital PWM (pulse width modulation) control pulse on the output performance, such as the dynamic response and static precision of power supply output, the current pre-estimating algorithm is proposed based on the LR (inductance and resistance) model of power supply output, and then the straightforward digital PID (proportional integral differential) control algorithm is modified. Meanwhile, the anti-disturbance characteristics of digital control system is improved effectively by pre-treating on the detecting signals of current and voltage, A/D sampling in phase with PWM control pulse, digital filtering, etc. The correctness and effectiveness of digital PID control algorithm based on current pre-estimation is validated by the control experimentations on the pulse variable polarity output of power supply.