中频电源的研究与实现

中频电源高功率因数和多闭环反馈的研究与的实现

I. INTRODUCTION

Mid-frequency ac power supply has a very widely application in many fields such as industry， national defense， navigation and aviation etc. Its frequency is commonly 400Hz and the power waveform required is a pure sinusoidal wave. Its harmonic content is not more than 5% and the operating voltage is 115V. In order to satisfy the requirements that the output is a pure sine wave， the sinusoidal pulse width modulation （SPWM） control technology with output voltage RMS or average value feedback is widely used. This can make the output voltage amplitude of the inverter power supply is steady state and no error. This control method has the advantage of simple structure and easy implementation. But because the SPWM control technology only pays attention to adopting appropriate switch mode design to achieve inverter output spectrum optimization and does not consider the switch point changes in the signal transmission process and the influence of load， there are disadvantages： （1） When inverter power supply output with nonlinear load， the low-order harmonic current of the load current will pass through the power resistance and cause output voltage waveform distortion. （2）The existence of dead band time will make SPWM wave contain the low-order harmonic which is not easily filter out and cause the output voltage waveform distortion. （3） The output voltage adjustment time with load mutation is long. The reason is that the system only has the voltage average

Fu-zhuan Wu， Dong-yun Wang， and Hai-bo Ma are with the School of Electrical and Information， Zhongyuan University of Technology， 41 Zhongyuan Road， Zhengzhou， China， 450007 （phone： 13938587251; e-mail： wfzh@zzti.edu.cn）。 value or RMS feedback and no instantaneous feedback. （4） The phase difference between the given voltage and output voltage is deeply affected by the load .In a three phase power system， the phase difference between three-phase outputs can not easily satisfy 120 o. The reference ［1-2］ adopt the analog control method with the combination of amplitude loop and double closed loop control based on capacitor current feedback to control 400Hz power. Because of using analog control method， its shortcoming is obvious. The reference ［3-5］ use similar methods and realize the digital control， however its controller design still takes the analogy design thinking and does not take into account the difference of digital control .In addition in order to eliminate steady state error， the amplitude loop is taken as the outer loop. Because the amplitude loop cannot promptly respond the output voltage changes， the power dynamic response speed is limited. Other digital control methods mostly adopt repetitive control or the combination method of repetitive control and other control methods ［7-9］， and they are more complicated. The computation and data storage is bigger for storing a lot of data and the repetitive controller dynamic performance is poor ［10］。 At present the study and research mainly focus on inverter power supply output stability problems and few papers relate to the grid influence of the input.