正弦波逆器的设计与研究.doc

PAGE PAGE 7 摘要 逆变技术是整流技术的逆向变换电源技术，将直流电转换成交流电的装置 称为逆变器。根据输出波形可分为方波逆变器和正弦波逆变器，目前多数负载要求输入为正弦波，因此正弦波逆变器得到了越来越多的研究和关注。对正弦波逆变器来说最重要的是控制电路，以脉宽调制( PWM)为基础的正弦脉宽调制(SPWM)技术是正弦波逆变器的一项关键控制技术，它以正弦波为调制波、以三角波或锯齿波为载波，通过调制输出的SPWM脉冲控制功率开关管的开通与关断，从而完成直流到交流正弦波的逆变过程。 本文在对逆变器结构和原理分析的基础上，设计完成DC-DC-AC两级高频正 弦波逆变器：输入侧直流电压12V通过推挽变换电路升压到370V左右，再由 370V直流电通过全桥变换电路得到220V／50Hz交流电。升压控制电路由PWM控制芯片SG3525与其外围电路组成，根据电路特点使直流输出高压不稳压而只有后级输出稳压，从而简化了滤波电路；全桥逆变控制电路采用SPWM倍频调制方式，即输出SPWM波频率为载波三角波频率的二倍，这样对调制电路的要求相对较低，且输出滤波电路更容易设计。本文SPWM控制电路采用常用运算放大器和数字芯片设计完成，在保证精度的前提下降低了成本，并且简化了由硬件实现 SPWM控制的电路结构。 通过计算电路各部分元件参数并制作出电感和变压器等线圈元件，本文制 作完成了一台正弦波逆变电源样机，并对电源进行安装及调试，最终得出实验 结果和波形，证实了该设计的可行性，达到了减小电源体积和成本的预期目标。关键词：逆变器，PWM，SPWM，倍频调制Abstract The inverter technology is contrary to the rectification technology．An inverter is a device which transforms direct current into alternating current．According to the output waveform，inverter can be divided into square wave inverter and sine—wave inverter．Currently most load demand input for sine wave，so sine wave inverter get more and more attention．The most important part of sine-wave inverter is the control circuit. Sine-wave pulse-width modulation(SPWM)which uses sine wave as modulation wave and triangular wave as carrier wave is a key technology which based on the theory of pulse-width modulation． In this paper, the structure and principle of the inverter al e analyzed at first．Then a DC-DC-AC two-stage high frequency inverter is designed：The input voltage 12V DC boost to 370V DC using a push-pull circuit；Then the 370V DC is tamed into 220V/50Hz AC using a full bridge circuit．The control circuit of the push-pull circuit is based on a PWM(pulse width modulation)control chip SG3525．According to the characteristics of the circuit, the output of this stage is not settled SO as to simplify the filter circuit；The full bridge circuit is conventional．The method of the full bridge control circuit is the SPWM(sinusoidal pulse width modulat