The photovoltaic power generation system can convert solar energy into different forms of electrical energy through the power converter. LLC resonant converter is widely used in such applications because of its low power loss and small electromagnetic interference.In order to solve the problem that the voltage range of LLC resonant converter is narrow under frequency conversion modulation

and it is difficult to cope with the wide range change of photovoltaic array output voltage

an improved LLC resonant converter based on rectifier side is proposed. The converter adopts hybrid modulation method to improve the topology of the secondary rectifier side of the circuit.It adds a plurality of capacitors and bidirectional switches on the secondary side

and then adjusts the voltage gain of the converter to ensure that the output voltage remains stable under the condition of large fluctuation of input voltage.This paper first analyzes the working principle of the converter

and then theoretically analyzes the proposed converter topology and hybrid modulation method

and then obtains the voltage gain range under different circuit structures and modulation methods. At the same time

through reasonable parameter design

the soft switching conditions of the converter are guaranteed. Under this modulation method

all the secondary side switches of the converter can realize soft switching

and realize zero voltage switching(ZVS)of the primary side switch and zero current switching(ZCS)of the secondary side diode.The rated power of the experimental prototype is set to 400 W

which further verifies the feasibility of the proposed converter.