The invention discloses an
alternating current-
direct current converting circuit and a control method thereof. The
alternating current-
direct current converting circuit comprises an input rectification circuit, a primary side input
filter capacitor, a primary side
inverter circuit, a drive circuit, an
isolation transformer, an auxiliary side rectification circuit, an auxiliary side
capacitor and a
control circuit, wherein the
control circuit is connected between the auxiliary side output
filter capacitor and the drive circuit, the drive circuit is connected with the primary side
inverter circuit, the primary side
inverter circuit and the primary side input
filter capacitor form a loop to form a clamping
resonance circuit, and inversion switching tubes work in a no-
voltage switching state. The auxiliary side rectification circuit has two work
modes of forward and flyback, and the first and second inversion switching tubes in the primary side inverter circuit are used as inversion switching tubes or clamping switching tubes according to work periods. According to the
alternating current-
direct current converting circuit and the control method thereof,
diode loss in the rectification loop can be reduced,
soft switching of the inversion switching tubes is achieved,
voltage stress and switching loss of a primary side switching tube and an auxiliary side
rectifier diode are reduced, and efficiency is improved.