The present invention relates to a DC-DC converter and to a method for controlling a DC-DC converter with high dielectric strength and reduced power losses. An optimized control of a potential-isolating multi-level half-bridge converter according to a phase-shifted full-bridge configuration with a novel modulation method is proposed.

A power conversion circuit includes: a MOSFET having a super junction structure; an inductive load; and a freewheel diode. A switching frequency of the MOSFET is 10 kHz or more. When the MOSFET is turned off, a first period during which a drain current decreases, a second period during which the drain current increases, and a third period during which the drain current decreases again appear in this order. The freewheel diode is an Si-FRD or an SiC-SBD, and current density obtained by dividing a current value of the forward current by an area of an active region of the freewheel diode falls within a range of 200 A/cm.sup.2 to 400 A/cm.sup.2 when the freewheel diode is the Si-FRD, and the current density falls within a range of 400 A/cm.sup.2 to 1500 A/cm.sup.2 when the freewheel diode is the SiC-SBD.

A multi-output power supply device includes an inductor, a first output terminal, a second output terminal, an FET, an FET, a chopper circuit, and a controller. The FET adjusts a current output from the inductor to the first output terminal. The FET adjusts a current output from the inductor to the second output terminal. The chopper circuit has the FET and the inductor. The FET is connected in parallel with the FET, and conducts or cuts off a current. The inductor is provided between the FET and the second output terminal. For example, the controller lowers a potential from the first output terminal by turning on the FET and sets a potential difference between a drain terminal and a source terminal of the FET to zero to suppress a switching loss when the FET is turned on.

A rectifying circuit includes: a first terminal; a second terminal; a third terminal disposed between the first terminal and the second terminal; a first rectifying element connected to the first terminal and the second terminal; a coil connected to the first terminal and the third terminal; a second rectifying element connected to the third terminal and the second terminal; a transistor including a source, an emitter, a drain, and a collector, the source or the emitter being connected to the third terminal; a power source including a positive electrode and a negative electrode, the negative electrode being connected to the second terminal; and a third rectifying element including an anode connected to the positive electrode of the power source and a cathode connected to the drain or the collector of the transistor.

An inverter circuit (120) is configured so as to perform synchronous rectification by six switching elements (130). The switching element (130) is formed of an unipolar device (SiC MOSFET in this case) using a wideband gap semiconductor. The inverter circuit (120) uses the body diode (131) of SiC MOSFET (130) as a freewheeling diode during synchronous rectification.

Embodiments of the present invention disclose a power converter and a related system. The power converter includes a controller and a power conversion circuit. The power conversion circuit is configured to convert an input power of an input power supply into an output power of a load, where the input power supply is an external power supply connected to the power converter. The controller is configured to control on/off of the first switch element, to implement connection/disconnection between the input power supply and the inductive element; and control the unidirectional conduction circuit to be turned on before the first switch element is turned on in the power conversion cycle.

A converter comprises a first switching element and a second switching element coupled between an input power source and an output capacitor and an inductor coupled to a common node of the first switching element and the second switching element, wherein the second switching element comprises a first diode and a first switch connected in series between a first terminal and a second terminal of the second switching element and a second diode connected between the first terminal and the second terminal of the second switching element.

A control method and a control circuit for a switching power supply circuit and the switching power supply circuit. The switching power supply circuit includes a main switching transistor, a synchronous rectifier and an inductive element. When a switching signal indicates that the synchronous rectifier is turned from on to off, and the main switching transistor is turned from off to on, a gate voltage of the synchronous rectifier is pulled down to be lower than a threshold voltage of the synchronous rectifier and higher than a zero voltage by using a resistor-capacitor delay effect and timing is started. When a gate voltage of the main switching transistor is detected to rise to a first voltage or the timing reaches a first time, the gate voltage of the synchronous rectifier is pulled down to the zero voltage.

A transient current in a rectifier circuit is effectively reduced. In the rectifier circuit, a current flows from a power supply to a coil when a transistor is turned ON. When the transistor is turned OFF, the current of the coil flows into a second rectifier.

A power converter is connected between a power supply source of a first direct current power and a power supply destination of a second direct current power obtained by performing power conversion on the first direct current power. The power converter includes: a switching element; a reactor; a first diode; a first capacitor; a second diode. The reactor is connected to a first end of the switching element. The first end of the switching element and a first end of the reactor are connected to a first connection point. A cathode of the first diode is connected to a second end of the reactor. The cathode of the first diode and the second end of the reactor are connected to a second connection point. The second diode includes an anode connected to the first connection point and a cathode connected to the power supply destination.