高精度逆变电源输出电压直流漂移的调偏控制

逆变器中的隔离环节、各功率器件等存在漂移和特性不对称以及正弦脉宽调制(sinusoidal pulse width modulation，SPWM)都会引起逆变电源输出电压的直流漂移。该文提出了一种高精度逆变电源输出电压直流漂移的调偏控制方案，系统采用基于现场可编程门阵列(field programmable gate array，FPGA)的全数字控制。给出了直流调偏控制的基本原理及其闭环控制系统。分析了模数转换器(analogue-to-digital converters，ADC)精度与数字脉宽调制(digital PWM，DPWM)精度之间的关系，并给出了抑制极限环振荡的必要条件。提出一种提高DPWM精度的新方法，可以进一步提高直流调偏控制的精度。最后，在一台单相8重化9电平电压型逆变器的实验平台上进行实验验证，实验结果表明了该控制方案的有效性。

Offset Control of DC Drift of High-precision Inverter Output Voltage

DC drift of inverters output voltage is introduced by drift and characteristic asymmetry of isolation section and power devices, and sinusoidal pulse width modulation (SPWM). A novel offset control of DC drift of for high-precision inverter output voltage is presented. The realization of the control system is based on field programmable gate array (FPGA). This paper analyzes theory and closed-loop control system for offset control of DC drift. The relationship of analogue-to-digital converters (ADC) resolution and digital PWM (DPWM) resolution are analyzed, and then a necessary condition for restraining limit cycle oscillations is put forward. A new scheme about increasing the effective resolution of DPWM is presented, which can improve resolution for offset control of DC drift. Finally, experimental results are analyzed in a signal-phase voltage source inverter operating in eight multiple and nine level. Experimental results confirm the value of the algorithm.