Abstract: A voltage conversion circuit includes: an AC/DC conversion unit, a DC/DC conversion unit, a first control unit, and a second control unit. The AC/DC conversion unit is connected to the DC/DC conversion unit through a direct current bus. The first control unit is configured to obtain a bus voltage on the direct current bus, and generate a first control signal when the bus voltage is less than a first voltage threshold; and the second control unit is configured to enter a heavy load mode when the first control signal is received, and output a first drive signal to the DC/DC conversion unit, where a duty cycle of the first drive signal is greater than a duty cycle of a drive signal output by the second control unit in a non-heavy load mode.

Abstract: The buck circuit includes a first switch component, a second switch component, a first freewheeling component, a second freewheeling component, an inductor, a first capacitor, and an over voltage protection OVP module. The first switch component and the first freewheeling component constitute a bridge arm. A first end of the inductor is connected to a midpoint of the bridge arm, and a second end of the inductor is connected to the second switch component. A first end of the second freewheeling component is connected to the second end of the inductor. A first end of the first capacitor is connected to the second switch component. The first capacitor is connected in parallel to the OVP module and a load of the buck circuit. The OVP module detects an output voltage of the buck circuit, and the output voltage of the buck circuit is an input voltage of the load.