A control circuit for controlling a switching converter having a low quiescent current. The control circuit has an error amplifying circuit, an on time generator, a first comparing circuit and a second comparing circuit. When the switching converter operates in a light load operation mode, the error amplifying circuit and the on time generator are deactivated. Meanwhile, the first comparing circuit compares a current sensing signal indicative of inductor current with a current reference signal to provide an off time control signal during an on state of a low side switch to determine an on moment of a high side switch. The second comparing circuit compares the voltage feedback signal with a voltage reference signal to provide an on time control signal to determine an off moment of the high side switch.

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 a three-level LLC circuit coupled between the pair of input terminals and the pair of output terminals. The circuit includes a first switch coupled with a first diode to define a first half-bridge and a second switch coupled with a second diode to define a second half-bridge. The power supply further includes a third switch coupled across the first diode and the second diode to short circuit the first diode and the second diode when the third switch is closed, and a control circuit including a voltage-controlled oscillator (VCO), at least one flip-flop and multiple logic gates to operate the three switches with zero-voltage switching (ZVS).

A zero-crossing detector to be installed in a ceiling fan includes: a first terminal; a second terminal; and a rectifier, an adjustor and a feedback generator that cooperatively generate a current signal based on an AC voltage between the first and second terminals. The current signal has a non-zero magnitude when the AC voltage causes a potential at the first terminal to be greater than a potential at the second terminal, and has a zero magnitude when otherwise. An average of the non-zero magnitude of the current signal is greater when the adjustor is in a working state than when the adjustor is in a power saving state. The feedback generator generates a feedback signal based on the current signal.

The present disclosure provides a control method for a DC converter and a DC converter. the DC converter comprises a switching circuit, a sampling circuit, and a controller, the method comprising: acquiring a duty ratio of a Burst cycle according to an output reference signal and an output signal; acquiring a first number of switching cycles and a burst on time according to the duty ratio of the Burst cycle, a first preset value, and a switching period of the switching device; acquiring a Burst cycle value according to the burst on time and the duty ratio of the Burst cycle; and generating a driving signal according to the Burst cycle value, the first number of switching cycles, and the switching period.

A method for converting an input voltage (V.sub.in) of a converter (1) into an output voltage (V.sub.out), the circuit comprising a first bridge arm consisting of two switches (A) and (B), a second bridge arm consisting of two switches (C) and (D), connected in parallel, a primary coil coupled to a secondary coil, and connected by a center point pole (PAB) of the first bridge arm, and by another center point pole (PCD) of the second bridge arm; the circuit further comprising a capacitor in parallel between the respective terminals of each of the switches (A, B, C, D); a third bridge arm formed by two switches (E) and (F), connected in series; each of the switches (A, B, C, D, E, F) being associated with a diode at the terminals of said switch; an injection inductance (L.sub.inj) connected to the center point (P.sub.AB) of the first bridge arm, and to the center point (P.sub.EF) of the third bridge arm; a monitoring-control unit configured to control the switches to turn them ON or OFF, according to a control cycle configured to ensure soft switching between ON and OFF.

A switch-mode power supply and a zero current detector for use therein. A zero current detector includes an input stage and an output stage. The output stage is coupled to the input stage. The output stage includes a detector output terminal, a first transistor, and a second transistor. The first transistor includes an input terminal and a control terminal. The input terminal is coupled to the detector output terminal. The control terminal is coupled to the input stage. The second transistor includes an input terminal, a control terminal, and an output terminal. The input terminal is coupled to the control terminal of the first transistor. The control terminal is coupled to the input terminal of the second transistor. The output terminal is coupled to ground.

A converter includes a power conversion circuit, a switching device, and a controller, and includes N phases, where N is 2 or 3. An input end of the power conversion circuit is connected to a direct current power supply, and the power conversion circuit converts a direct current output by the direct current power supply into an alternating current. The switching device includes at least the following two stages: a first-stage switching device and a second-stage switching device. The first-stage switching device and the second-stage switching device separately include N switches, and the N switches are connected in series to the N phases respectively. An output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series.

Inverter systems, circuits and associated control techniques for providing efficient delivery of high-frequency (HF) power and radio-frequency (RF) power into variable load impedances while maintaining resistive/inductive loading of the constituent inverters for zero voltage switching (ZVS) are described. The inverter architecture and associated control techniques for providing efficient delivery of HF into variable load impedances includes a first inverter having an output coupled to an input of an immittance converter. An output of the immittance converter is coupled to a second inverter. The second inverter maybe either serially or parallel coupled between the output of the immittance converter and a load.

A wireless power transfer (WPT) system regulation method and system for implementing zero voltage switching (ZVS) in a wide power range are provided. The method includes: determining, according to a topology structure of a WPT system and based on a linear state equation, a phase-shift angle boundary and a switching frequency boundary of an inverter that meet ZVS; fixing a switching frequency at a resonance frequency of the WPT system, and determining, in a phase-shift manner, a phase-shift range and a corresponding first voltage output range for implementing ZVS; determining a frequency variation range of a frequency modulation method; determining an optimal switching frequency based on corresponding switching frequencies and phase-shift angles that meet ZVS at different expected output voltages of the WPT system; determining a second voltage output range for implementing ZVS at the optimal switching frequency; and regulating the WPT system by using different regulation methods.

A switching power supply comprises a power converter having a transformer, a low side switch configured to draw current from a supply voltage through a primary winding of the transformer and a high side switch configured to couple the primary winding of the transformer to a snubber capacitor. A controller is configured to synchronously control the opening and closing of the low side switch and the high side switch so as to form a regulated output voltage. A first voltage is generated at a node between the low side switch and the high side switch. The controller is further configured to open the high side switch during each switching cycle when the first voltage reaches a determined level. The determined level is higher than the supply voltage by an amount that is adjusted dependent on a monitored level of the supply voltage.