Abstract: A power converter includes two control switches, two synchronous rectifier switches, two inductors, a voltage detector that detects a voltage across one of the control switches, and a controller that controls each switch to shift on and off phases of one of the control switches and one of the synchronous rectifier switches by 180° from on and off phases of the other control switch and the other synchronous rectifier switch. The controller determines the on-time of the target synchronous rectifier switch in accordance with the voltage across the one control switch after a lapse of a predetermined time period since turn-off of the one synchronous rectifier switch, and determines the on-time of the other synchronous rectifier switch as the determined on-time of the target synchronous rectifier switch.

Abstract: The power conversion device can undergo autonomous search control for ZVS without a larger circuit area or lower reliability. The power conversion device performs, in each switching cycle, an operation of turning the control switch (CTLSW) on and afterward off while the synchronous rectification switch (SRSW) is off, and then turning the synchronous rectification switch on and afterward off while the control switch is off. Whether the inductor current (iL) is positive or negative is detected at the detection timing backed by a predetermined period (Text) from a timing at which the synchronous rectification switch switches from on to off, based on the detection result, the on-period (TOFF) of the synchronous rectification switch is corrected.

Abstract: A power conversion device includes: a first switch; a second switch; a first inductor; a first current sensor circuit that detects an electric current flowing to the first inductor; and a first resonant period detection circuit that detects a resonant period of a first resonance phenomenon that occurs by switching operations of the first switch and the second switch. The first resonance phenomenon occurs due to energy that has accumulated in the first inductor in a first energy application period. The first resonant period detection circuit detects the resonant period of the first resonance phenomenon based on the result of comparison between a reference voltage and a voltage generated from a resonance current flowing to the first inductor due to the first resonance phenomenon and detected by the first current sensor circuit.

Abstract: The power conversion device can undergo autonomous search control for ZVS without a larger circuit area or lower reliability. The power conversion device performs, in each switching cycle, an operation of turning the control switch (CTLSW) on and afterward off while the synchronous rectification switch (SRSW) is off, and then turning the synchronous rectification switch on and afterward off while the control switch is off. Whether the inductor current (iL) is positive or negative is detected at the detection timing backed by a predetermined period (Text) from a timing at which the synchronous rectification switch switches from on to off, based on the detection result, the on-period (TOFF) of the synchronous rectification switch is corrected.

Abstract: A bidirectional switch module includes a plurality of bidirectional switches and a mount board. Each of the plurality of bidirectional switches includes a first source electrode, a first gate electrode, a second gate electrode, and a second source electrode. On the mount board, the plurality of bidirectional switches are mounted. In the bidirectional switch module, the plurality of bidirectional switches are connected in parallel.

Abstract: A substrate electric potential stabilization circuit is configured to be connected to a bidirectional switch element including a first main electrode, a second main electrode, and a backside electrode. The stabilization circuit includes a first switch connected to the first main electrode and the backside electrode in series between the first main electrode and the backside electrode, a second switch connected to the second main electrode and the backside electrode in series between the second main electrode and the backside electrode, and a through-current prevention circuit configured to prevent the first switch and the second switch from being turned on simultaneously. The substrate electric potential stabilization circuit prevents a through-current flowing in this circuit.

Abstract: A speed-up circuit is configured to be provided between a power supply terminal and a gate of a semiconductor switching element. An impedance element is configured to be provided between a signal input terminal and a node, the node being between the speed-up circuit and the gate of the semiconductor switching element. In the speed-up circuit, a second field effect transistor is connected in series to a first field effect transistor and is configured to be connected to the gate of the semiconductor switching element. The impedance element has an impedance higher than an impedance of the speed-up circuit when both the first field effect transistor and the second field effect transistor are in an ON state.

Abstract: A substrate electric potential stabilization circuit is configured to be connected to a bidirectional switch element including a first main electrode, a second main electrode, and a backside electrode. The stabilization circuit includes a first switch connected to the first main electrode and the backside electrode in series between the first main electrode and the backside electrode, a second switch connected to the second main electrode and the backside electrode in series between the second main electrode and the backside electrode, and a through-current prevention circuit configured to prevent the first switch and the second switch from being turned on simultaneously. The substrate electric potential stabilization circuit prevents a through-current flowing in this circuit.

Abstract: A bidirectional switch module includes a plurality of bidirectional switches and a mount board. Each of the plurality of bidirectional switches includes a first source electrode, a first gate electrode, a second gate electrode, and a second source electrode. On the mount board, the plurality of bidirectional switches are mounted. In the bidirectional switch module, the plurality of bidirectional switches are connected in parallel.

Abstract: A speed-up circuit is configured to be provided between a power supply terminal and a gate of a semiconductor switching element. An impedance element is configured to be provided between a signal input terminal and a node, the node being between the speed-up circuit and the gate of the semiconductor switching element. In the speed-up circuit, a second field effect transistor is connected in series to a first field effect transistor and is configured to be connected to the gate of the semiconductor switching element. The impedance element has an impedance higher than an impedance of the speed-up circuit when both the first field effect transistor and the second field effect transistor are in an ON state.

Abstract: A nitride semiconductor device includes: a stacked structure portion having an active region; first and second main electrodes extending in a first direction; and a lead-out line (second lead-out line) electrically connected to the second main electrode and extends to one side in the first direction. The first main electrode has a first tip at an end which is on the side to which the lead-out line extends. The second main electrode has a second tip at an end which is on the side to which the lead-out line extends, and has, at a second tip-side in the first direction, a tapered portion having a width in a second direction which decreases with decreasing distance to the second tip. The lead-out line has a region projecting in the second direction from the tapered portion, and the first tip does not project further in the first direction than the second tip.