Ac/dc pfc converter using a half bridge resonant converter, and corresponding conversion method
AssigneePhilips Lighting Holding B.V.
InventorsReinhold ELFERICH, David Llewellyn JOHN
Life of this patent
Estimating the term…
Abstract
An AC/DC PFC converter comprises an LLC PFC pre-regulator and a DC/DC converter output stage. The output stage has a feedback unit adapted to provide a feedback signal (in addition to the conventional feedback of the bus voltage error) to the control circuit of the PFC pre-regulator for modulating the controlled output voltage of the PFC pre-regulator in dependence on the output power and/or the input current and voltage. In this way, the total harmonic distortion of the input of the converter can be reduced by controlling the gate switching in the PFC pre-regulator.
Claims15
An AC/DC PFC converter, comprising:
- a PFC pre-regulator, comprising:
- an AC input;
- a rectifier for rectifying a mains voltage;
- a half bridge inverter comprising a high side switch and a low side switch, wherein an output is defined from a node between the switches;
- an LLC circuit coupled to the output;
- and
- a control circuit for generating a gate drive signal for controlling the switching of the high side and low side switches thereby to generate a controlled output voltage (vbus), wherein a high gate drive signal turns on one switch and turns off the other switch and a low gate drive signal turns off the one switch and turns on the other switch;
- and
- an output stage, comprising:
- a DC/DC converter;
- a feedback unit adapted to provide a feedback signal to the control circuit of the PFC pre-regulator for modulating the controlled output voltage (vbus) of the PFC pre-regulator in dependence on at least the output power of the output stage, wherein a set-point for the controlled output voltage is varied synchronously with the mains voltage, such that an imposed bus voltage variation is synchronous with the rectified input mains voltage.
An AC/DC PFC conversion method, comprising:
- operating a PFC pre-regulator by:
- rectifying a mains voltage;
- controlling a half bridge inverter comprising a high side switch and a low side switch by generating a gate drive signal and providing an output from a node between the switches to an LLC circuit thereby to generate a controlled output voltage, wherein a high gate drive signal turns on one switch and turns off the other and a low gate drive signal turns off the one switch and turns on the other switch;
- and
- providing an output from the LLC circuit to an output stage;
- and
- operating the output stage by:
- implementing DC/DC conversion;
- and
- providing a feedback signal from the output stage to the PFC pre-regulator for modulating the controlled output voltage of the PFC pre-regulator in dependence on at least the output power of the output stage, wherein a set-point for the controlled output voltage is varied synchronously with the mains voltage, such that an imposed bus voltage variation is synchronous with the rectified input mains voltage.
Dependencies are inferred from the claim text.