Research On Full Digital Control Of Totem-pole Bridgeless PFC Based On GaN

With the increase of energy shortage,energy-saving and emission-reduction have become a hot issue.As for power supply,it is very important to improve power efficiency.The SMPS is usually composed of PFC and DC-DC converter.For PFC,the traditional solution uses the CCM mode BOOST circuit in the average current mode.While it is mature and widely used,its performance has reached its limit.To further improve the efficiency of PFC,a variety of new topologies have risen in recent years.A hot topic is the bridgeless PFC circuit,which improves the efficiency of the circuit by removing the input bridge rectifier.The definition of power factor correction is introduced in this paper.The differences between CCM,DCM and CRM are compared and analyzed.At the same time,the advantages and disadvantages of all kinds of bridgeless PFC circuit topologies are compared and analyzed.On this basis,the totem-pole bridgeless PFC is made further research.Totem-ploe bridgeless PFC use MOSFET as the main switch,but the MOSFET body diode has larger reverse recovery time and charge that limits the application of totem-ploe bridgeless PFC in practice.By contrast analysis of the parameters characteristic of GaN,MOSFET,COOL-MOSFET,the reverse recovery process and the reverse recovery charge of the GaN device are very small,and it can reach the zero-reverse recovery,So the problem that the totem pole can't work in current continuous mode can be solved by using the GaN device as the main switch,Meanwhile,PSIM6.0 simulation software is used to simulate and verify the theoretical analysis.Comparison and analysis between digital control and analog control,digital control is more simple,convenient,convenient debugging.The engineering calculation software Mathcad is used to calculate the parameters,and the parameters are used to design the inductance,capacitance and switch.At the same time,the voltage and current detection method is designed.To verify the rationality of the theoretical design.According to Mathcad calculation parameters,a 300 W prototype of the totem pole bridgeless PFC which works in the current continuous mode was made.Inductor current waveform and so on are obtained by testing the prototype.The rationality is verified by analyzing the waveform that the GaN devices can make the totem-pole bridgeless PFC work in the current continuous mode.Meanwhile,the totem-pole bridgeless PFC can achieve higher efficiency that can be verified by testing the efficiency of the prototype.