三相四桥臂逆变器的非数字化控制策略

Non-Digital Control Strategy of Three-Phase Four-Leg Inverter

三相四桥臂逆变器较成熟的控制策略都需依赖数字信号处理器来实现,但数字化控制的精确性受较多因素制约,其控制效果在一些场合并不理想。本文在分析了三相四桥臂逆变器数学模型的基础上,研究了一种三相四桥臂逆变器的非数字化控制策略,各相桥臂采用了改进的电压电流双闭环控制,通过加入谐振控制器提高逆变器的稳态精度,通过补偿零序谐波提高逆变器的输出正弦度和直流母线电压利用率;第四桥臂采用零序谐波电压PWM控制,保证了逆变器具有较强的带不平衡负载能力。仿真和实验验证了该控制策略具有方法简单、易于模拟电路实现、逆变器输出波形质量高、带不平衡负载能力强、动静态性能良好等优点。

Many mature control strategies of three-phase four-leg inverter are realized by digital signal processor. But the accuracy of digital control strategies was restricted by many factors. The effect of the control is not good in some fields. In this paper, based on the analysis of the mathematical model of three-phase four-leg inverter, a non-digital control strategy is researched. The improved voltage and current double closed-loop control method is used to control each leg of three phase. The steady-state precision of the inverter is improved by adding a resonant controller. The output wave quality and the utilization of DC bus voltage are improved by compensating zero sequence harmonic.The zero sequence voltage PWM control method is used to control the fourth leg. It can ensure that the inverter has a good capability when it is with unbalanced loads. Simulation and experiment verify that this control strategy has many advantages such as simple and easy realized by analog circuit, output waveform with high quality, good capacity with unbalanced load, good dynamic and static performance.