A flyback converter includes a power transformer, a primary side switch, a secondary side switch and a controller. A secondary side switching signal has an SR pulse for achieving synchronous rectification, and a ZVS pulse for achieving zero voltage switching. The ZVS pulse is enabled according to a first characteristic of a resonance waveform, whereas, a primary side switching signal is enabled according to a second characteristic of resonance waveform. When an output current increases, the primary side switching signal is disabled during an inhibition interval, such that primary side switching signal does not overlap with the ZVS pulse, thereby preventing the primary and secondary side switches from being both conductive simultaneously. The inhibition interval is correlated with a rising edge of the primary side switching signal in a previous switching period and a resonance period of the resonance waveform.

A dimmer is provided for controlling power to a load, the dimmer having a ground leakage power supply deriving power from a connection of the dimmer to ground. The power supply may be a switching-mode power supply that can be the sole or primary power supply to power operation of the dimmer, including operation of the controller.

Embodiments described herein provide a zero-crossing detector (ZCD) for a direct current to direct current (DC-DC) converter. The ZCD includes a ZCD integrator configured to receive a switch voltage and an output voltage of a power stage of the DC-DC converter and to generate a zero-crossing detect signal based, at least in part, on the received switch voltage and output voltage, where the zero-crossing detect signal is configured to indicate an output current in an output inductor of the power stage of the DC-DC converter is approximately zero. The ZCD may also include a ZCD offset calibrator configured to receive the switch voltage and generate a ZCD calibration offset based, at least in part, on the received switch voltage, where the ZCD integrator is configured to generate the zero-crossing detect signal based, at least in part, on the ZCD calibration offset.

A hybrid topology power converter includes a three-level circuit module and a cascaded H-bridge circuit module. A control method includes the following steps. Firstly, a zero sequence component is injected into a total modulation wave, thereby generating a compensated total modulation wave. Then, a first voltage signal is generated according to the compensated total modulation wave. An H-bridge modulation wave is generated according to the compensated total modulation wave and the first voltage signal. A three-level driving signal is generated according to the first voltage signal, and an H-bridge driving signal is generated according to the H-bridge modulation wave. A duty cycle of at least one switch element of the three-level circuit module is adjusted according to the three-level driving signal. A duty cycle of at least one switch elements of the cascaded H-bridge circuit module is adjusted according to the H-bridge driving signal.

Power-packet-switching circuits (and methods and systems) in which at least one port uses series-connected combinations of bidirectional switches to connect a link inductor (or transformer), with selectable polarity, to an outside line. Optionally, series-connected combinations of bidirectional switches are used for phase legs in some ports, while single bidirectional switches are used for the phase legs in other ports. This can be particularly advantageous where the converter interfaces between lines at significantly different operating voltages. By using B-TRANs as the series-combined elements of the combinations of switches, voltage-dividing circuitry is not needed to equalize the voltages seen by the individual devices in each combination.

An isolated step-up converter having first and second stages is described herein. The second stage can provide either DC or AC output based on the various topologies described. Resonance inductors and capacitors are used and tuned to a commutation frequency in some embodiments. Capacitors and inductors are also used in the first stage.

A control circuit and a control method for a power converter are provided. The power converter includes a plurality of resonant tanks and a plurality of switches disposed between an input terminal and an output terminal. The switches correspond to a first mode and a second mode, respectively, and the control circuit includes a first switch control circuit, a first zero current detection circuit, a second zero current detection circuit, a first switch off detector, a modulation time calculation module, a second switch control circuit, a third zero current detection circuit, a fourth zero current detection circuit, and a second switch off detector. The control circuit uses a plurality of zero current detection circuits to perform time modulations on a plurality of rectifier switches in the switches.

A multiphase power supply including a controller and phases can respond to a drop in load level by reducing all but one active phase to reduce power consumption. If the load level drops further, further reduction of the power consumption could be achieved by reducing, changing, or disabling the functions of some circuits within the active phase during these conditions. Estimating these conditions, however, may be difficult for a controller when the communication between the controller and the phase is limited. The disclosure describes an active phase that estimates a state of the load based on a sensed output current and a pulse width modulation control signal. The active phase may change its operating mode to match the estimated state of the load so that lighter load conditions consume less power. Furthermore, the idle phase(s) may nearly turn off all function except PWM detection to save power. Because this mode change is local to the phase, no additional communication with the controller is required.

A method includes detecting a first current flowing through a first clamping device coupled to a gate of a power switch, determining whether an inductor current reduces to zero based upon a first comparison between the first current and a first predetermined current level, and after determining the inductor current reduces to zero, determining whether a drain voltage of the power switch enters a valley of a resonant ringing based upon a second comparison between the first current and the first predetermined current level.

An electric working machine of an example of the present disclosure includes: a motor; a power supply portion; a controller; and a voltage detector. The power supply portion generates a DC voltage to drive the motor by rectifying an AC voltage supplied from an AC power source and smoothing by a capacitor. The controller controls energization of the motor. The voltage detector detects the AC voltage. The controller is configured to interrupt the energization when the voltage detector does not detect the AC voltage.