A resonant converter includes a transformer, a resonant network, control circuit, primary and secondary circuits. One of the primary switches is turned on from a first switching moment until a second switching moment. The resonant network is coupled between the primary circuit and the primary winding. A current of the resonant network changes a direction at a first moment between the first and second switching moments. The secondary circuit is coupled to the secondary winding. One of the secondary switches is turned on during first and second preset time interval to increase the current in a direction by the secondary winding being clamped by a preset voltage, in which the output current is increased in an opposite direction or equal to zero.

A resonant converter includes a transformer, a resonant network, control circuit, primary and secondary circuits. One of the primary switches is turned on from a first switching moment until a second switching moment. The resonant network is coupled between the primary circuit and the primary winding. A current of the resonant network changes a direction at a first moment between the first and second switching moments. The secondary circuit is coupled to the secondary winding. One of the secondary switches is turned on during first and second preset time interval to increase the current in a direction by the secondary winding being clamped by a preset voltage, in which the output current is increased in an opposite direction or equal to zero.

A switch-mode power supply includes a pair of input terminals for receiving an alternating current (AC) or direct current (DC) voltage input from an input power source, a pair of output terminals for supplying a direct current (DC) voltage output to a load, and at least four switches coupled in a three-level LLC circuit arrangement between the pair of input terminals and the pair of output terminals. The power supply also includes a voltage doubler power factor correction (PFC) circuit coupled between the pair of input terminals and the three-level LLC circuit, and a control circuit coupled to operate the at least four switches to supply the DC voltage output to the load.

An integrated circuit for a power supply circuit including a transistor configured to control a current flowing through a coil. The integrated circuit is configured to drive the transistor. The integrated circuit includes: a determination circuit configured to determine whether a predetermined time period has elapsed since a power supply voltage of the integrated circuit rises to a first predetermined level; an oscillator circuit configured to output an oscillator signal, which has a first frequency before lapse of the predetermined period, and changes in a range at least from the first frequency to a second frequency higher than the first frequency after the lapse of the predetermined time period; and a driver circuit configured to switch the transistor responsive to the oscillator signal during and after the predetermined time period, the switching causing an on period of the transistor to gradually increase in the predetermined time period.

A system for extracting energy from an energy storage device configured to supply direct current (DC) energy at a nominal voltage rating comprises a first node dimensioned and arranged to receive direct current energy from the energy storage device. Embodiments include a self-oscillating circuit having primary and secondary windings wound around a ferrite core, wherein a positive terminal of the primary winding is tied to the negative terminal of the secondary winding at the first node, and wherein a positive terminal of the secondary winding is coupled to a second node, the second node being coupled to a load requiring power to be supplied at one of a voltage less than, equal to, or higher than the nominal voltage. Some embodiments further include a transistor having a base resistively coupled to a negative terminal of the primary winding and a collector coupled to the second node.

Resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches (S1, S2). The self-oscillating feedback loop sets a switching frequency of the power converter (100) and comprises a first intrinsic switch capacitance (CGD) coupled between a switch output and a control input of the switching network and a first inductor (LG). The first inductor (LG) is coupled in-between a first bias voltage source and the control input of the switching network and has a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage (VBias) applied to the first inductor (LG). The output voltage (V0UT) of the power converter (100) is controlled in a flexible and rapid manner by controlling the adjustable bias voltage (VBias).

A method and an apparatus for transferring electric power to an electrical load (105); the method includes steps of: converting a direct electric current into an electric tension wave, applying the electric tension wave in inlet to at least a couple of electric capacitors (125, 130); supplying the electrical load (105) with the electric tension in outlet from the capacitors (125, 130).

Provided is a high-frequency power supply device capable of causing an appropriate current to flow through a transformer. A self-oscillation high-frequency power supply device is provided with a DC power supply, an LC resonant circuit, a switching circuit, and a transformer. The LC resonant circuit includes an induction coil for plasma generation and a capacitor. The switching circuit includes a semiconductor element, the switching circuit being configured to subject DC power supplied from the DC power supply to switching processing to supply high-frequency power to the LC resonant circuit. The transformer includes a primary coil included in the LC resonant circuit and a secondary coil connected to the semiconductor element to turn on/off a semiconductor element. The transformer has a coaxial structure in which the primary coil and the secondary coil are coaxially provided. The LC resonant circuit includes a resistor connected in parallel to the primary coil.

A power supply device with low loss includes an input switch circuit, a transformer, a first capacitor, an output stage circuit, and a detection and control circuit. The input switch circuit generates a switching voltage according to an input voltage. The output stage circuit generates an output voltage. The output stage circuit includes a first rectifying switch element and a second rectifying switch element. The detection and control circuit detects a first output current flowing through the first rectifying switch element so as to generate a first control voltage, and it detects a second output current flowing through the second rectifying switch element so as to generate a second control voltage. The first rectifying switch element is selectively closed or opened according to the first control voltage. The second rectifying switch element is selectively closed or opened according to the second control voltage.

In a described example, a circuit includes a mode control circuit having an input and a mode control output. The mode control output is adapted to be coupled to a mode input of a DC-to-DC power converter. The mode control circuit is configured to provide a mode control signal at the mode control output. The mode control signal has a frequency and a duty cycle for causing the power converter to operate within an inaudible frequency range by transitioning the power converter between a power save mode and a pulse width modulation (PWM) mode. The mode control circuit is configured to control the duty cycle responsive to the input of the mode control circuit.