PWM逆变电源双环控制技术研究

华中科技大学

硕士学位论文

PWM逆变电源双环控制技术研究

姓名：何俊

申请学位级别：硕士

专业：电力电子与电力传动

指导教师：彭力

20070209

摘要

逆变器作为UPS系统的核心部分，要求它能够输出高质量的电压波形，尤其是在非线性负载情况下仍能够得到接近正弦的输出波形，因此各种各样的逆变器波形控制技术得以发展。其中瞬时值反馈控制技术是根据当前误差对逆变器输出波形进行有效

的实时控制，如果控制器设计合理，则既可以保证系统具有较好的稳态性能，同时可

以保证系统具有较快的响应速度。本文主要研究内容是PWM逆变电源电流内环电压外环双环控制技术，对逆变器双环控制进行了理论分析，并结合仿真和实验对其控制

性能进行了深入的研究。

基于状态空间平均法给出了PWM逆变器的传递函数形式和状态方程形式的数学模型，详细分析了死区效应、过调制和非线性负载对单相全桥逆变器输出电压的影响，指出减小输出阻抗是增强系统非线性负载适应能力的合理方案。

分析比较了电感电流内环电压外环和电容电流内环电压外环两种双环控制方式，

提出了带负载电流前馈补偿的电感电流内环电压外环双环控制方式，重点研究了逆变器电容电流内环电压外环双环控制。依据电流内环所采用调节器的不同，分别讨论了

电流内环采用P调节器、电压外环为PI调节器和电流内环、电压外环均为PI调节器两种双环控制方式。采用极点配置的方法设计控制器参数，在闭环系统配置相同的阻

尼比和自然频率的前提下对两种双环控制方式进行仿真比较。仿真结果表明电流内环和电压外环均采用PI调节器的逆变器双环控制方式能够达到较好的动、静态特性，

特别是其非线性负载带载能力较强；电流内环采用P调节器、电压外环为PI调节器的逆变器双环控制方式稳态性能较好，但其抗非线性负载扰动能力不及电流内环和电压外环均采用PI调节器的双环控制方式，理论分析和仿真结果表明增大双环控制系

统的期望自然频率可以改善系统的抗非线性负载扰动能力。

基于理论分析和计算，在一台样机上进行电容电流内环电压外环的双环模拟控制

实验，实验结果与理论分析相符。

关键词：PWM逆变器双环控制极点配置模拟控制

Abstract

As the key part of the UPS(Uninterruptible Power Supply) system, inverters are required to get high quality output voltage waveform. To achieve nearly sinusoidal output voltage even with nonlinear loads, many waveform correction techniques have been proposed. Since the instantaneous feedback control technique is a real-time control method according to the current error of output waveform, once the controller is designed properly, it could achieve nice static characteristics with good dynamic response. The dissertation focuses on the research for dual loop control technique with instantaneous voltage and current feedback for PWM inverters. Both dynamic and static characteristics are analysed by simulations and experiments.

Based on the state-space averaging and linearization technique, the mathematical model is given in form of transfer function and state equations. The influence of dead-time, over-modulation and nonlinear loads on output voltage in single-phase full-bridge inverters is analyzed in detail. The method which reduces equivalent output impedance of the close loop system to eliminate the disturbance of nonlinear load is reasonable.

The voltage and current dual loop control system is divided into inductor current feedback and capacitor current feedback. Both of them are analysed and compared in the paper, the dual loop control with inductor current feedback and load current forward feed compensation included. The dual loop control with capacitor current feedback is applied in the following simulation and experiment by analog method. Depending on the difference of controller for the current loop, the dual loop control is classified into two methods: current loop using P controller with voltage loop using PI controller（Dual loop PI-P control）and both current loop and voltage loop using PI controller（Dual loop PI-PI control）. Controller parameters are obtained with pole assignment technique in the condition that both dual loop PI-P control system and dual loop PI-PI control system have the same desired damping ratio and nature frequency. The simulink results show that dual loop PI-PI control technique for inverters could get nice static characteristic and well dynamic response. It could get high quality output waveforms even with nonlinear load. Dual loop PI-P control inverters