Single Stage Pfc Super Low Voltage Isolated Converter Pesearch

With the fast development of computer and telecommunication, the super low voltage and large current power supply is a hot spot in the power electronics field. Considering the cost efficiency, the single stage PFC is widely researched in the small power devices. The single-stage PFC super low-voltage isolated converter is researched in this paper which is a new experiment from the view of technology. At first, the single stage topology worked in DCM mode is analyzed, compared and classified, and make the Sheppard-Taylor topology as the researched one; then the working process and input current power factor in theory are analyzed in this paper. According to the state-space averaging method the model of the DCM converter is deduced, by which the static functions is obtained. The log-magnitude character of the open loop is equal to the two orders system according to the Bode graph gotten by the AC transfer function. The critical conditions of some parameters are obtained based on the energy conservation. The simulation methods in power electronics circuits are analyzed and the large signal non-linear simulation based on the matlab-simulink is accomplished, at the same time some practical problems in pspice software are discussed and the system open ioop log-magnitude character is obtained from the other point of view based on the averaging concept. The power supply of super low-voltage and large current is a new requirement. Adapting the synchronous rectifier technology reduces the loss, and the efficiency is ascended. The experiment proves that the efficiency is improved from 56% to 83% and verifies that the synchronous rectifier technology has great advantage in that case. At last the choosing of the circuit抯 parameters are discussed and the prototype of 45W is made by those parameters from the fore calculations, which verifies the theoretical analysis.