【作者】 周樑；

【导师】 彭力；

【作者基本信息】 华中科技大学 ， 电力电子与电气传动， 2006， 硕士

【摘要】 在不允许供电中断的重要用电场合,大量使用着UPS系统。而逆变器是UPS系统的核心部件,要求它具有高质量的输出电压波形。尤其是在带非线性负载情况下仍然要有接近正弦的输出波形。因此,发展了多种多样的逆变器波形控制技术。本文的主要内容是PWM逆变电源瞬时值反馈控制技术,瞬时值反馈控制是根据当前误差对逆变器的输出波形进行有效的实时控制,如果控制器设计合理,既可以保证系统具有很好的稳态性能,同时也可以保证系统有快速的响应速度。全文围绕电压单环瞬时值控制技术及电容电流内环和电压外环双环瞬时值控制技术这两种控制方法,进行了理论分析,同时结合仿真和实验来探讨如何提高PWM逆变电源的静、动态性能,改善输出波形质量。基于状态空间平均法和线性化技术给出了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,指出引入输出电压瞬时值反馈控制来解决非线性负载带来的扰动,抑制谐波是合理的方案。对于逆变电源的控制策略,可以采用重复控制、无差拍控制、滑模变结构控制或者PID控制,由于采用PID控制容易兼顾控制系统的稳态性能和动态性能。而且算法简单、易于实现、可靠性高,已经成为迄今为止最通用的控制方法。本文研究了基于极点配置的PID控制器的设计方法,仿真结果显示这种PID控制器性能优越,同时还提出一种PI调节器结合电压微分反馈的调节方式,并指出这种调节方式和PID调节其实是等效的,而且是一种简化的双环形式,因此是一种简单而有效的调节方式。对现今普遍采用的电压电流双环控制,分为电感电流内环电压外环和电容电流内环电压外环两类进行了分析比较,重点研究了单相逆变器电容电流内环电压外环双环控制系统特性,并对其内、外环调节器的选取及其设计做了大量仿真,仿真结果显示电容电流内环电压外环双环控制系统具有比电压单环瞬时值反馈控制系统更优越的性能。本文最后在一台样机上实现了电容电流内环电压外环双环控制,实验结果与理论分析相符,能够得到较满意的动态和稳态波形。更多还原

【Abstract】 Uninterruptible Power Supply(UPS)systems are widely used for supplying critical loads which can not afford utility power failure. A inverter is the core of a UPS system. High quality output voltage waveform is required for these inverters. To achieve nearly sinusoidal output voltage even with nonlinear loads, many waveform correction techniques have been proposed. This dissertation focuses on the research of the instantaneous feedback technology of PWM inverters. Since the instantaneous feedback technology is a real-time control according to the current error of the output waveform .Once the controller is designed properly, it can improve system dynamic response with nice static characteristics. Analysis and simulations are centered on two control approaches which are single loop controller with instantaneous voltage feedback and dual-loop control with voltage and current feedback to discuss how to improve both dynamic and static characteristics, thereby to reform the output waveform of PWM inverter.Based on the state-space averaging and linearization technique, the mathematical model is given in form of transfer function and states 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 brings output voltage feedback in the control loop to eliminate the disturbance of nonlinear load is reasonable. Of all sorts of strategies, there are repetitive control, deadbeat control, sliding-mode control and PID control. The PID control method is in favor of balancing the dynamic and static characteristics of the control system, easy to be calculated and realized. Above all it is reliably, and thus it is becoming the most universal control method. The design method of PID controller based on pole-assignment is proposed in this paper. The simulations indicate that this PID controlled inverter provides nice characteristics. A method of PI controller combined with instantaneous differential voltage is also proposed, which is equivalent to PID control in essence and can be seen as a simplified dual-loop form. Accordingly it is a simple but effective adjustment.The voltage and current dual-loop control system is divided into inductor-current feedback and capacitor-current feedback. The comparison of both is given in the paper. The characteristics of the inverter with the dual-loop control using capacitor-current feedback and voltage are obtained and analyzed. A mass of simulations are made to design both the inner and outer controller. The simulations indicate that this voltage and current dual-loop control system is superior to single loop controller with instantaneous voltage feedback in characteristics.Finally, a single-phase inverter applying output voltage and capacitor-current feedback control is researched in the paper and the experimental results accord with theoretic analyze. And it can get nice static characteristic and well dynamic response.更多还原