A method for reducing or eliminating current and voltage transients in a device including: providing the device, wherein the device comprises a transistor with a gate; and controlling the gate, wherein the gate is turned off to a non-zero value in a presence of the positive current flow and wherein the gate is turned on in a presence of the negative current flow; reducing the negative current flow; and reducing or eliminating current and voltage transients in the device.

A nitride semiconductor device includes: a substrate; a nitride semiconductor layer above the substrate; a high-resistance layer above the nitride semiconductor layer; a p-type nitride semiconductor layer above the high-resistance layer; a first opening penetrating through the p-type nitride semiconductor layer and the high-resistance layer to the nitride semiconductor layer; an electron transport layer and an electron supply layer covering an upper portion of the p-type nitride semiconductor layer and the first opening; a gate electrode above the electron supply layer; a source electrode in contact with the electron supply layer; a second opening penetrating through the electron supply layer and the electron transport layer to the p-type nitride semiconductor layer; a potential fixing electrode in contact with the p-type nitride semiconductor layer at a bottom part of the second opening; and a drain electrode.

Synchronous rectification control circuit and switching power supply system are provided. The circuit includes a sampling circuit, a turn-on comparison circuit, a turn-off comparison circuit, a drive control circuit, an anti-accidental turn-on circuit, wherein the sampling circuit has a first terminal coupled to a first output terminal of a transformer; the anti-accidental turn-on circuit has a first input terminal coupled to a second terminal of the sampling circuit; the turn-on comparison circuit has a first input terminal coupled to the second terminal of the sampling circuit, a second input terminal coupled to an output terminal of the anti-accidental turn-on circuit; the turn-off comparison circuit has an input terminal coupled to the second terminal of the sampling circuit; the drive control circuit has a first input terminal coupled to an output terminal of the turn-on comparison circuit, a second input terminal coupled to an output terminal of the turn-off comparison circuit.

An apparatus includes a switching circuit, a resonant circuit coupled to an output of the switching circuit, a rectification circuit coupled between the resonant circuit and an output of the apparatus, and a controller coupled to the switching circuit. The controller, during a soft start-up operation of the power supply, is configured to switch a plurality of switches with a variable limited maximum duty cycle at a minimum frequency and after the variable limited maximum duty cycle reaches the limited maximum duty cycle at the minimum frequency, simultaneously switch the frequency to a maximum frequency and switch the duty cycle to a minimum duty cycle at the maximum frequency for a same on-time as the limited maximum duty cycle at the minimum frequency.

An air conditioning device includes a buck converter which comprises a switching device, an inductor, a diode and at least one capacitor. The diode is a SiC diode, and the buck converter further includes an attenuator associated to the SiC diode and a ferrite bead associated to the switching device.

A loss optimization control method for modular multilevel converters (MMCs) under fault-tolerant control is disclosed. The method includes the following steps: when a fault of a SM in a MMC occurs, bypassing the faulty SM to achieve fault-tolerant control; suppressing the fundamental circulating current using a fundamental circulating current controller; respectively calculating the loss of each SM in faulty arms and healthy arms by using loss expressions of different switching tubes in SMs of the MMC; aiming at the loss imbalance between the arms of the MMC, taking the loss of a healthy SM as the reference, adjusting the period of capacitor voltage sorting control in the faulty SMs, achieving the loss control over the working SMs in the faulty SMs, and finally achieving the loss balance of each SM in the faulty arms and the healthy arms. Compared with the conventional methods, the proposed method is easier to implement and does not increase the construction cost of MMCs.

A soft switching sub-circuit forming part of or for use with a circuit. The soft switching sub-circuit comprises a bridge switching circuit. The soft switching sub-circuit is configured and operable to provide a varying current output that tracks output current from the bridge switching circuit to create a substantially zero current through at least one switch component of the bridge switching circuit to enable soft switching.

The switching power supply device is provided with a high-withstand voltage first transistor, a first electrode of which being connected to a first node; a low-withstand voltage second transistor, a first electrode of which being connected to a second electrode of the first transistor, and a second electrode of which being connected to a second node; and a drive circuit. Each of the first and second transistors has a parasitic diode connected in the forward direction between the second and first electrodes. The drive circuit, in a case where electrical current is to flow from the first node to the second node, turns on the first and second transistors, and, in a case where electrical current is to flow from the second node to the first node, turns on the first transistor, and turns off the second transistor.

Provided is a power conversion circuit including at least: a switching element that opens and closes an inputted voltage via a reactor; and a commutating diode that passes a current in a direction of an electromotive force by a voltage including at least the electromotive force generated from the reactor when the switching element is turned off, the commutating diode including a gallium oxide-based Schottky barrier diode.

An electric power converter includes an inverter, an insulating transformer, and a rectifier. The inverter converts an input DC voltage, supplied from a DC power supply, to an AC voltage outputted at an AC output side of the inverter, and includes at least one semiconductor switching device made of wide bandgap semiconductor material configured to carry out turning-on and turning-off operations at a specified frequency to thereby invert the DC voltage to the AC voltage at the specified frequency; and at least one freewheeling diode made of silicon-based semiconductor material respectively connected to the at least one switching device in inverse parallel.