A control circuit for a power factor correction (PFC) circuit, the control circuit includes a multiplier having first, second, and third multiplier inputs and a multiplier output. The control circuit has an adder having first and second inputs and an output. The first input of the adder is coupled to the multiplier output. The control circuit further includes a root mean square (RMS) calculation circuit configured to determine a square of a root mean square of an input sinusoidal voltage. The RMS calculation circuit has an output coupled to the second multiplier input. An input voltage square calculation circuit is configured to determine a square of the input sinusoidal voltage. The input voltage square calculation circuit has an output coupled to the third multiplier input.

A power supply apparatus with step-up and step-down conversion includes a primary-side rectifying/filtering circuit, a step-up converter, a full-bridge LLC converter, a primary-side controller, a secondary-side rectifying/filtering circuit, a voltage regulator, and a secondary-side controller. The primary-side rectifying/filtering circuit rectifies and filters an AC input voltage into a DC input voltage. The primary-side controller controls the step-up converter to step up the DC input voltage to a step-up voltage, and controls the full-bridge LLC converter to convert the step-up voltage to a conversion voltage. The secondary-side rectifying/filtering circuit rectifies and filters the conversion voltage into a DC output voltage. The secondary-side controller controls the primary-side controller to provide the step-up control signal and the conversion control signal and provides a voltage regulation signal to control the voltage regulator so as to regulate the DC output voltage to an output voltage for supplying power to the load.

A variable voltage generator circuit is described for generating, from a substantially constant supply voltage V.sub.S, a variable high-voltage control voltage V.sub.C for a variable power capacitor (1) having a variable-permittivity dielectric. The control voltage generator circuit comprises a top-up circuit (10) for maintaining the voltage V.sub.Cin on an input capacitor (12) at least at supply voltage V.sub.S, and a bidirectional DC-DC converter circuit (20) having a variable voltage conversion factor G controlled by control input signal (27). The bidirectional DC-DC converter (20) is arranged to convert voltage, at the voltage conversion factor G, between the input capacitor voltage V.sub.Cin and the output voltage V.sub.C. When V.sub.C<G×V.sub.Cin, the DC-DC converter circuit (20) uses charge stored in the input capacitor (12) to charge the capacitive load (1). When V.sub.C>G×V.sub.Cin, the DC-DC converter circuit (20) uses charge stored in the load capacitance (1) to charge the input capacitor (12).

A voltage booster powered by a primary electrical source for providing an adjustable voltage across the load, while a current regulator in series with the load maintains the desired current. When the voltage drop across the current regulator exceeds an upper threshold, the voltage booster's output voltage is reduced to a lower level to reduce the power dissipated by the current regulator, to improve efficiency. When the voltage drop across the current regulator is less than a lower threshold, the voltage booster output is increased to a higher level. In burst mode operation, the voltage booster output alternates between a full voltage and zero voltage, and an optional capacitor provides voltage across the resistive load during discharge. An optional diode can ensure that the capacitor discharges through the load in cases where the voltage booster output is not floating.

The present disclosure relates to an overvoltage protection circuit and a charging device. A voltage applied to a PFC power supply on an input side is collected through an input voltage sampling circuit and an amplifier circuit, and a data processing capability of a charging management circuit is used to determine whether the applied voltage exceeds a preset voltage threshold. The preset voltage threshold refers to a voltage that is not greater than a minimum withstand voltage of an input device of the charger. The power factor correction power supply is controlled to operate to charge the battery to be charged when it is determined that the voltage applied does not exceed the preset voltage threshold, to prevent damage to the input device due to a connection to two phases of voltage.

A control circuit includes: a flip-flop having an output configured to be coupled to a control terminal of a transistor and for producing a first signal; a comparator having an output coupled to an input of the flip-flop, and first and second inputs for receiving first and second voltages, respectively; a transconductance amplifier having an input for receiving a sense voltage indicative of a current flowing through the transistor, and an output coupled to the first input of the comparator; a zero crossing detection (ZCD) circuit having an input configured to be coupled to a first current path terminal of the transistor and to an inductor, where the ZCD circuit is configured to detect a demagnetization time of the inductor and produce a third signal based on the detected demagnetization time; and a reference generator configured to generate the second voltage based on the first and third signals.

A controller for a boost power factor correction (PFC) converter. The controller is configured to operate the boost PFC converter in multiple operating modes, including a continuous conduction mode (CCM), a transition mode (TM), and a hybrid mode in which the controller operates the converter in both CCM and TM within a same line cycle. An example controller includes a current control loop and a mode transition circuit. The current control loop is configured to compute an inductor current for each of first and second operation modes, based on a current sample taken, for example, during a boost synchronous rectifier conduction period of the converter. The mode transition circuit includes digital logic circuitry and is configured to generate a pulse indicating that one, two or all three of: zero-voltage switching (ZVS) has been achieved; the synchronous rectifier conduction period is active; and/or one of TM or hybrid mode is active.

An on-board charger is provided with a bulk capacitor adapted to couple to a vehicle traction battery and a relay for receiving electrical power from an external power supply and to pre-charge the bulk capacitor. A power factor correction (PFC) circuit is connected between the bulk capacitor and the relay. The PFC circuit includes a switch that is adjustable between an on-position and an off-position. The switch enables current flow from the relay to the bulk capacitor in the off-position. A snubber circuit is coupled to the switch to damp a transient voltage present at the switch during a transition from the on-position to the off-position. A processor is programmed to control the switch.

A method for driving an electronic switch in a power converter and a power converter are disclosed. The method includes: driving an electronic switch (1) coupled to an inductor (2) in the power converter, wherein driving the electronic switch (1) includes driving the electronic switch (1) in a plurality of drive cycles by a drive signal (S.sub.DRV), Driving the electronic switch (1) in at least one of the plurality of drive cycles includes: determining a desired duration (T.sub.ON_DES) of a current (I.sub.1) through the switch (1); and adjusting a duration (T.sub.DRV) of an on-level of the drive signal (S.sub.DRV) dependent on the desired duration (T.sub.ON_DES) and a delay time (T.sub.DEL) obtained in a preceding drive cycle. The delay time (T.sub.DEL) is a time duration, in the preceding drive cycle, between a first time instance (t1) when the drive signal (S.sub.DRV) changes from the on-level to an off-level and a second time instance (t2) when a current through the electronic switch (1) falls below a predefined threshold.

The present invention discloses a charging power supply circuit and a control method thereof, the charging power supply circuit includes a PFC circuit, a driver module, and a high-voltage output circuit and a low-voltage output circuit both connected to said PFC circuit, wherein the PFC circuit is connected to AC mains, and the drive module is used to set the operation range of said PFC circuit to the range near the zero point of AC input voltage. Using the technical solution of the present invention can achieve keeping the topology on the demand for isolation and reduce the volume and cost of PFC circuits.