A contactless power supply device includes a power transmitter, and a power receiver. The power receiver includes: a resonant circuit including a receiver coil and a resonant capacitor; a rectifier circuit configured to rectify the power output from the resonant circuit; a voltage detection circuit configured to measure the output voltage from the rectifier circuit and obtain a measurement value for said output voltage; and a first communication device. The power transmitter includes: a transmitter coil; a power supply circuit including a power source and a plurality of switching elements between the power source and the transmitter coil; an auxiliary coil for electromagnetic coupling with the transmitter coil; a variable capacitance circuit configured to connect to the auxiliary coil and adjust the electrostatic charge therein; and a control circuit configured to control the electrostatic charge in the variable capacitance circuit in accordance with the measurement value for the output voltage.

A DC-DC power converter has an auxiliary tank cascaded to share an efficiency tank's inductor, capacitor, and transformer. Switching transistors pump the auxiliary tank at startup to provide a boost current. The switching frequency is reduced in steps and the voltage gain and power of the converter sensed until the voltage gain matches a voltage gain calculated for the efficiency tank. Then tank switchover occurs and transistors to the efficiency tank are pumped with the last switching frequency used by the auxiliary tank, and the auxiliary tank is not pumped. Since the voltage gains before and after tank switchover are equal, no output voltage deviation or current spike occurs. A voltage sag or failure switches back to the auxiliary tank at a switching frequency determined by a dynamic contour line where the voltage gains of the two tanks are equal for the current power state.

An LLCC Secondary Overtone Resonant (LLCC-SOR) power converter obtains dramatically higher efficiency with light loads by providing a resonance in the transformer secondary that is approximately tuned to an odd order overtone of the upper primary switching frequency, an upper frequency limit of the primary switching frequency, and a secondary duty cycle control that engages once the upper primary switching frequency limit is reached. The transformer circuit resonates in an LLCC-SOR mode that regulates the output voltage when the maximum frequency limit is reached. In operation, the gain of the resonant circuit is raised above its regulation point under light loads, forcing the controller into duty cycle mode. The secondary current completes an odd number of oscillations per single oscillation of the primary current, and the primary current returns to near zero after each switching transition. Also, a zero-voltage switching condition is maintained on the primary switch.

The invention relates to a high-frequency resonant power conversion system for transferring power from an oscillator to a load or vice-versa, the system comprising components with at least one fluctuating parameter and is configured to control the value of a defined variable selected from: a certain current, a certain voltage, a phase difference between a certain voltage and a certain current, and a certain power; the system further comprising a virtual impedance creation loop which is configured to create a virtual component, said virtual component forming a basis for changing amplitude and a phase of the oscillator, thereby to compensate for a deviation from the controlled variable due to said fluctuations.

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 single-stage AC/DC converter includes a boost PFC AC/DC converter and a half-bridge split-capacitor DC/DC converter. The boost PFC AC/DC converter includes a boost inductor, and the half-bridge split-capacitor DC/DC converter includes an inductor in series with a primary winding of a transformer. A method of operation of a single-stage AC/DC converter that includes a boost PFC AC/DC converter and a half-bridge split-capacitor DC/DC converter includes modulating a switching frequency of at least one switch. The method may further include maintaining a constant duty cycle, for example a duty cycle of 0.5. An implementation of the boost inductor in a boost PFC AC/DC converter of a single-stage AC/DC converter includes a variable boost inductor, such as two inductors of approximately equal inductance, and a boost inductor switching circuit, such as two single-pole, double-throw relays.

A method for minimizing DC capacitance of a cascade multilevel converter is provided. On the basis of balancing of capacitor voltages, the method estimates instantaneous value of the DC side capacitor voltages in a circuit through an energy conservation law, and uses a proportional resonance controller to control a grid-connected current to realize adjustment of the grid-connected current without static difference, such that the cascade multilevel converter can operate in a small capacitance mode, the system volume is greatly reduced, the system cost is reduced, the control is easy to be implemented, and the capacitor voltage is free from overshoot and the system has a better rapidity.

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 high frequency power supply system provides highly regulated power and frequency to a workpiece load where the highly regulated power and frequency can be independent of the workpiece load characteristics by inverter switching control and an inverter output impedance adjusting and frequency control network that can include precision variable reactors with a geometrically-shaped moveable insert core section and a stationary split-bus section with a complementary geometrically-shaped split bus section and split electric terminal bus section where the insert core section can be moved relative to the stationary split-bus section to vary the inductance of the variable reactors.

An electronic ballast with a single stage circuit structure includes a detection device for detecting a voltage, current, and phase of an AC input power source; a rectifier bridge; a full bridge inverter circuit; and an inverter controlling circuit. When an output terminal of the full bridge inverter circuit is connected to the gas discharge lamp as a load, the electronic ballast further includes a series resonant capacitor Cs and a series resonant inductor L. By additionally providing the series resonant capacitor Cs and the series resonant inductor L to the electronic ballast, a zero-crossing point of a unidirectional sinusoidal direct current is able to effectively solve the HID extinguishing problem due to under-voltage thereof. Since a conduction angle of the entire unidirectional sinusoidal half wave of the HID is increased, the PF value is effectively increased and the harmonics is effectively reduced.