A DC power supply unit is provided that allows for improving efficiency and reducing harmonic currents. A DC power supply unit includes: a bridge rectification circuit having diodes and MOSFETs; a reactor that is arranged between the AC power supply and the bridge rectifier circuit; a smoothing capacitor that is connected to an output side of the bridge rectifier circuit and smoothes a voltage; and a converter control unit that executes, based on predetermined threshold values, a diode rectification control that uses diodes and parasitic diodes of the MOSFETs, a synchronous rectification control that switches the MOSFETs in synchronization with a polarity of the voltage of the AC power supply, a partial switching control that repeats partially short-circuiting the reactor multiple times in a half cycle of the AC power supply, or a fast switching control that short-circuits the reactor at a predetermined frequency over a full AC cycle.

A DC power supply unit is provided that allows for improving efficiency and reducing harmonic currents. A DC power supply unit includes: a bridge rectification circuit having diodes and MOSFETs; a reactor that is arranged between the AC power supply and the bridge rectifier circuit; a smoothing capacitor that is connected to an output side of the bridge rectifier circuit and smoothes a voltage; and a converter control unit that executes, based on predetermined threshold values, a diode rectification control that uses diodes and parasitic diodes of the MOSFETs, a synchronous rectification control that switches the MOSFETs in synchronization with a polarity of the voltage of the AC power supply, a partial switching control that repeats partially short-circuiting the reactor multiple times in a half cycle of the AC power supply, or a fast switching control that short-circuits the reactor at a predetermined frequency over a full AC cycle.

A DC power supply unit is provided that allows for improving efficiency and reducing harmonic currents. A DC power supply unit includes: a bridge rectification circuit having diodes and MOSFETs; a reactor that is arranged between the AC power supply and the bridge rectifier circuit; a smoothing capacitor that is connected to an output side of the bridge rectifier circuit and smoothes a voltage; and a converter control unit that executes, based on predetermined threshold values, a diode rectification control that uses diodes and parasitic diodes of the MOSFETs, a synchronous rectification control that switches the MOSFETs in synchronization with a polarity of the voltage of the AC power supply, a partial switching control that repeats partially short-circuiting the reactor multiple times in a half cycle of the AC power supply, or a fast switching control that short-circuits the reactor at a predetermined frequency over a full AC cycle.

A driver circuit for a switching circuit is provided. The driver circuit includes a PWM terminal, first to fourth gate control terminals configured to provide first to fourth control signals, a first output terminal, and a second output terminal. In a normal operation mode, during a first period of a first cycle, the first control signal and the fourth control signal are of a first voltage level, and during a second period of the first cycle, the second control signal and the fourth control signal are of the first voltage level. In a power loss mode, during the first period of the first cycle, the second control signal and the third control signal are of the first voltage level, and during the second period of the first cycle, the second control signal and the fourth control signal are of the first voltage level.

A driver circuit for a switching circuit is provided. The driver circuit includes a PWM terminal, first to fourth gate control terminals configured to provide first to fourth control signals, a first output terminal, and a second output terminal. In a normal operation mode, during a first period of a first cycle, the first control signal and the fourth control signal are of a first voltage level, and during a second period of the first cycle, the second control signal and the fourth control signal are of the first voltage level. In a power loss mode, during the first period of the first cycle, the second control signal and the third control signal are of the first voltage level, and during the second period of the first cycle, the second control signal and the fourth control signal are of the first voltage level.