电容电流瞬时值反馈控制逆变器的数字控制技术研究

采用电容电流反馈的双闭环瞬时值控制的逆变器具有输出波形正弦性好、动态响应快、输出外特性硬和稳态精度高等特点。该文基于状态观测器，对电容电流反馈瞬时值控制电路的数字实现方法进行研究，提出了基于电容电流反馈的解耦控制方法；设计了电流内环数字控制器，提出了一种电容电流采样时序，采用该采样时序可以真实反映电容电流开关周期内的电容电流平均值；提出了基于PWM逆变桥离散化模型的电容电流观测方法，可对电容电流做出准确观测，补偿数字控制器的采样延时和计算延时；提出了瞬时值电压控制外环的滤波方法，以提高输出电压的稳态精度。仿真和实验结果表明，该方案可以达到模拟电路实现双环控制的效果。

STUDY ON DIGITAL CONTROL TECHNIQUE FOR INVERTERS WITH INSTANTANEOUS CAPCITOR-CURRENT FEEDBACK

This paper presents a novel digital control scheme for dual loop instantaneous feedback inverter based on the state-observer. A decoupling control strategy is proposed under the feedback of capacitor current. A digital controller with inner current loop is designed using a new sampling sequence of capacitor current, and the average capacitor current in a switching period is reflected in real-time. A measuring method of current based on a discrete model of the full-bridge PWM inverter is proposed to compensate the delay time of sampling and computing. To increase the precision of output voltage, a filtering method for controlling the outer instantaneous voltage loop is adopted. The simulation and experiment results show that the inverter with this novel digital control strategy can achieve the same performance with analogy control strategy and takes the advantages of good sinusoidal output waveform, fast dynamic response, excellent load characteristic and high precision of output voltage.