Bridgeless boost pfc charger for inverters

[jerry24]

Pls I am confused as to what switching waveform to use to achieve pfc as close to 1 as possible .
I have ac coming in do I switch in an halfsine waveform for each half cycle or do I switch I an inverted halfsinewavefor for each half cycle . Pls ca someone explain to me . I want to achieve an efficiency such that at everypoint in the input ac voltage voltage is boosted for my charger . For example at 1v of the input ac my dutycycle has to be at the highest and at the peak of the input voltage my dutycycle has to be least ....this behavior can only be achieved by the inverted halfsine switching but what I see mostly online is an halsine waveform of current for pfc chargers. .

 

[D.A.(Tony)Stewart]

Yes the Sine wave reference can be demuxed by inverting the -ve of the half wave table to generate a full cycle in half the memory.

 

[FvM]

An ideal PFC charger is current controlled, the current setpoint waveform should be a sine in any case. You are apparently referring to the PWM modulation respectively switcher average output voltage waveform. Modulation ist set by the current controller and not necessarily the same waveform as current setpoint, it's e.g. different if the output stage is two quadrant "bridgeless" (two transistors and two diodes) topology and low output load causes DCM inductor current.

In CM operation, modulation follows sine waveform. Gate signal of the low side (boost) switch is inverted, in so far its duty cycle shows "inverted sine". waveform.