A direct-current power supply apparatus includes: a reactor having one end connected to an alternating-current power supply; a bridge circuit, connected to an opposite end of the reactor, converting an alternating-current first voltage output from the alternating-current power supply into a direct-current voltage; and a current detector detecting an alternating current flowing between the alternating-current power supply and the bridge circuit. The reactor reduces an inductance in accordance with an increase of the alternating current and, when the alternating current exceeds a first current, has an inductance lower than one third of an inductance at which a current does not flow in the reactor. The bridge circuit performs an active operation when the detection value of the alternating current is larger than or equal to the first current and performs a passive operation when the detection value of the alternating current is lower than the first current.

In some examples, an apparatus includes: a ramp generation circuit having a ramp control input and a ramp output, the ramp control input coupled to a power factor correction (PFC) output terminal; a comparator having a comparator output and first and second comparator inputs, the first comparator input coupled to the ramp output, the second comparator input coupled to a PFC switch current sensing terminal; and a pulse width modulation (PWM) generation circuit having a PWM control input and a PWM output, the PWM control input coupled to the comparator output, and the PWM output coupled to a PFC switch control terminal.

A power device includes a power factor corrector, an auxiliary capacitor, a switching device, an auxiliary boost circuit, a controller and a voltage conversion device. The switching device has a first end electrically connected to the output end of the power factor corrector, and a second end electrically connected to one end of the auxiliary capacitor. An output end of the auxiliary boost circuit is electrically connected to the output end of the power factor corrector, an input end of the auxiliary boost circuit is electrically connected to a middle end of the switching device, and a ground end of the auxiliary boost circuit is electrically connected to another end of the auxiliary capacitor. The controller is electrically connected to the switching device and the auxiliary boost circuit. The input end of the voltage conversion device is electrically connected to the output end of the power factor corrector.

A direct power converter includes a converter that rectifies a single-phase AC voltage, converts AC power into DC power, and outputs first instantaneous power; a power buffer circuit that receives and supplies power between the converter and a DC link and that performs buffering second instantaneous power; and an inverter that converts a DC voltage at the DC link into a second AC voltage and outputs the second AC voltage. A period for which a current that flows from the converter to the power buffer circuit continuously flows in a period shorter than a half-period of the AC voltage is longer when third power input to the inverter, fourth power output by the inverter, or an average value of the first instantaneous power decreases to a value which is less than a first threshold, from a value which is greater than or equal to a second threshold that is greater than or equal to the first threshold.

A method for detecting a variation of input voltage. The method is generating an indication signal based on the input voltage, and comparing the input voltage with a first reference signal. The first reference signal is smaller than the indication signal, and if the input voltage is consistently smaller than the first reference signal during a first time duration from the moment when the input voltage is decreased to the first reference signal, the indication signal is decreased after the first time duration.

A power system includes first and second power supplies, and a control circuit. The control circuit is configured to control the first power supply to regulate its output voltage at a first value, enable the second power supply, increase the output voltage of the first power supply to a second value in response to the second power supply being enabled, increase an output voltage of the second power supply to a third value, and decrease an output current of the first power supply and increase an output current of the second power supply to transition between electrically powering the load with the first power supply and electrically powering the load with the second power supply. Other example power system and methods for controlling a power transition between power supplies are also disclosed.

A PFC circuit includes: a boost inductor, an auxiliary winding, an auxiliary switch tube, a main switch tube, a clamping capacitor, a series resistor and a control module; the boost inductor and the auxiliary winding have mutual inductance, a first terminal of the auxiliary winding is connected to a first terminal of the auxiliary switch tube, a second terminal of the auxiliary switch tube is connected to a first terminal of the clamping capacitor, a second terminal of the clamping capacitor is connected to a first terminal of the series resistor, and a second terminal of the series resistor is connected to a second terminal of the auxiliary winding; the main switch tube is connected between the boost inductor and the ground; and the control module is respectively connected to a control terminal of the main switch tube and a control terminal of the auxiliary switch tube.

A class-D amplifying system includes: a class-D amplifier circuit configured to convert an input signal to a switch control signal in pulse width modulation fashion, wherein the switch control signal controls switches to operate a first inductor and a second inductor, thus converting an input power to a positive output signal and a negative output signal which are complementary to each other, to thereby drive a load; and a power converter circuit, which generates a direct current (DC) power supply according to at least one of the positive output signal and the negative output signal, wherein the DC power supply supplies at least a portion of power to the class-D amplifier circuit.

A power factor correction (PFC) controller applied to a primary side of a power converter includes a feedback pin, a sensing pin, a current detecting circuit, an output voltage detecting circuit, and a determination circuit. The current detecting circuit is coupled to the feedback pin and the sensing pin for detecting an output current of a secondary side of the power converter according to a feedback voltage of the feedback pin and a sensing voltage of the sensing pin. The output voltage detecting circuit is coupled to the feedback pin for detecting an output voltage of the secondary side of the power converter according to the feedback voltage. The determination circuit is coupled to the current detecting circuit and the output voltage detecting circuit for turning on or turning off a PFC circuit coupled to the power converter according to the output current and the output voltage.

The present disclosure relates to systems and configurations for phase-shift autotransformers and multi-pulse rectifiers. A phase-shift autotransformer includes a wiring configuration for first, second and third magnetic cores, the wiring configuration including primary input and phase-shift windings. The primary input windings are configured to provide a first and second primary input inductances, and phase-shift windings of the wiring configuration are configured to provide multiple inductances for each phase-shift winding. A multi-pulse rectifier is provided including a phase-shifting autotransformer, a diode bridge rectifier configuration coupled to output of the autotransformer and a filtering capacitor coupled to the diode bridge rectifier. Other embodiments are directed to use of the multi-use rectifier system with vehicle charging station, such as an Electric Vehicle Supply Equipment (EVSE).