Methods and apparatus provide compensation for impedance changes in a network energized by an amplifier, such as a class E amplifier. In embodiments, bus voltage amplifier fundamental AC output voltage can be used to generate a feedback signal for adjusting impedance of one or more components in the network. In embodiments, the amplifier fundamental AC output voltage is determined from current to the load, wherein the load is coupled to the amplifier by an LCL impedance matching network.

An inrush current suppression device is an inrush current suppression device that suppresses an inrush current flowing from a DC power supply through a mechanical switch, and includes: a first capacitor having one end connected to a positive terminal of the DC power supply through the mechanical switch; a semiconductor switching element connected to the other end of the first capacitor and a negative terminal of DC power supply between the other end of the first capacitor and the negative terminal of the DC power supply; a resistance element connected in parallel to the semiconductor switching element; and a control circuit for controlling the semiconductor switching element. The control circuit has a first output port, and controls ON time and OFF time of the semiconductor switching element by outputting a PWM signal from the first output port to the semiconductor switching element after the mechanical switch is closed.

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 includes a switch circuit, a resonant circuit, a first transformer, an output rectifier, a feedback circuit, and a controller. The switch circuit generates a switch voltage according to an input voltage, a first clock voltage, and a second clock voltage. The resonant circuit includes a variable capacitor and a variable inductor. The resonant circuit generates a resonant voltage according to the switch voltage, a first control voltage, and a second control voltage. The first transformer generates a transformation voltage according to the resonant voltage. The output rectifier generates an output voltage according to the transformation voltage. The feedback circuit and the controller detect a sensing voltage relative to the output rectifier. The feedback circuit determines the first control voltage according to the sensing voltage. The controller determines the second control voltage according to the sensing voltage.

A soft switching resonant converter is disclosed. The converter includes a power switch operable to connect and disconnect a DC link rail node and an output node. A resonant capacitor is coupled with the power switch. An auxiliary leg is coupled with a DC link midpoint node and the output node. An active damper is coupled in series with the resonant capacitor and the output node and is controllable to provide a first resistance of the active damper in a first state and a second resistance of the active damper in a second state, the first resistance having a lower magnitude than the second resistance. A driver controls the damper switch to provide a first resistance during the soft switching operation of the power switch and a second resistance after the soft switching operation of the power switch.

A primary unit for an inductive charging system includes a primary coil, which is configured to generate a magnetic field in response to a coil current through the primary coil; a first inverter, which is coupled to the primary coil via a first capacitor and which is configured to charge and/or discharge the first capacitor based on a first input voltage; and a second inverter, which is coupled to the primary coil via a second capacitor and which is configured to charge and/or discharge the second capacitor based on a second input voltage. The primary unit has a control unit, which is configured to identify capacitance information with respect to an effective capacitance of a primary resonant circuit of the primary unit, and to actuate the first inverter and the second inverter depending on the capacitance information in order to effect the coil current through the primary coil.

A power transmitting device includes: an inverter circuit; a power transmitting antenna connected to the inverter circuit, and being electromagnetically coupled to a power receiving antenna in a power receiving device to wirelessly transmit electric power thereto; a detector to detect an output voltage and an output current of the inverter circuit; and a control circuit to control the inverter circuit. The control circuit consecutively drives the inverter circuit at a plurality of frequencies, determines from among the plurality of frequencies a frequency at which a phase difference that is indicative of a lag of a phase of the output current relative to a phase of the output voltage becomes largest, and performs power transmission by driving the inverter circuit at an operating frequency that is based on the determined frequency.

A quasi-resonant auto-tuning controller includes a zero-voltage crossing detection circuit and a valley tuning finite-state machine having a look-up table. The zero-voltage crossing detection circuit receives a reference voltage and receives an auxiliary signal from an auxiliary winding. The zero-voltage crossing detection circuit produces a comparison signal having pulses when the auxiliary signal is less than the reference voltage. The valley tuning finite-state machine produces a divided pulse width based on the comparison signal, stores the divided pulse width of each pulse in the look-up table, determines, from the comparison signal, that the auxiliary signal is less than the reference voltage, waits a time period corresponding to the divided pulse width stored in the look-up table if the auxiliary signal is less than the reference voltage, and produces a valley point signal after waiting the time period.

A switched capacitor modulator (SCM) includes a RF power amplifier. The RF power amplifier receives a rectified voltage and a RF drive signal and modulates an input signal in accordance with the rectified voltage to generate a RF output signal to an output terminal. A reactance in parallel with the output terminal is configured to vary in response to a control signal to vary an equivalent reactance in parallel with the output terminal. A controller generates the control signal and a commanded phase. The commanded phase controls the RF drive signal. The reactance is at least one of a capacitance or an inductance, and the capacitance or the inductance varies in accordance with the control signal.

The present disclosure includes by controlling at least either one of a switching frequency of a switching element (S) or a duty ratio indicating an ON period of the switching element, securing delay time from voltage at both ends of the switching element reaches zero voltage by resonance of the resonant circuit (L.sub.0, C.sub.0) in an OFF state of the switching element until the switching element is turned on, and turning on the switching element within the delay time.