Research On High Power Factor Switching Mode Power Supply

With the development of the power electronics technology,the demand ofswitching power supply is getting greater and greater, along with the requirement ofhigh performance and high power factor are getting higher and higher. Full-bridgediodes are widely usded for rectifier in the input circuit of traditional switching powersupply，and high-capacity capacitor filter is usded in the output circuit.Though this kindof rectifier circuit is simple,reliable and lower cost, it will put a large number ofharmonic and reactive power into the power grid. As a result,it can cause a serious“pollution” for power grid and make power factor lower.In view of the above question,the paper takes the high power factor switching power supply as reserch object, firstly,PWM rectifier technology have been deeply reserched on, and applied it in theswitching power supply electric circuit, replaced traditional circuit to improve thepower factor.In this paper,the operating principle and control strategy of single-phase voltagesource PWM rectifier which is the pre-stage of high power factor switching powersupply were analyzed firstly, this system use the fixed turn-on frequency triangularwave comparison ditect current control method, in order to reduce the distortion ofinput current in PWM rectifier circuit, proposed the control strategy based on the outputripple voltage compensation;then the operating principle of DC/DC power inverter wasdetailed analyzed, the topology was also chosed; and then the circuit design processes ofall circuits of high power factor switching power supply are detailed analyzed.The40Whigh power factor switching power supply which has two output are designed.The single-phase Voltage Source PWM Rectifier(VSR) and the DC/DC powerinverter had been analyzed by Matlab7.6and Saber2007simulation software, andfinally draw a comparison between the high power factor switching power supply whichusing VSR and APFC. The simulation experiment verifies that the proposed strategybased on VSR not only improve the power factor more effectively, but also reduce theserious problem of current harmonics pollution on electric grid system, enabling thesystem to run efficiently, steadily and safely. Part of the experiment testified the PWM pulse control are reasonable and feasible, which has a certain theory value and practicalvalue.