# Active Power Factor Correction Circuit Not Working

#### Cyanners

Joined Jan 18, 2022
6

Hi all. I have made this boost converter power factor correction circuit and i cannot seem to get it to work correctly. The load voltage and current seem to be ok but the supply current is still made up of sharp spikes. I believe my values are correct but I am not too sure anymore. The specifications I am working towards are:

Vin = 240Vrms
Supply Frequency = 50Hz
Switching Frequency = 50kHz
Output Voltage = 400V
Total Output Power = 500W
Output Voltage Ripple = 15% of Output Voltage
Maximum Input Current Ripple = 1.75A

Ive included some of my calculations to show my process on selecting the component values. I believe my inductor workings are wrong however so I did not include them. Any help is greatly appreciated. Thank you.

#### Papabravo

Joined Feb 24, 2006
21,225
For starters your input power is 240 VAC(rms) * 1.75 Amperes = 420 Watts
Your output power is 500 Watts

YOU CAN'T GET MORE POWER OUT THAN YOU PUT IN!!!

#### AlbertHall

Joined Jun 4, 2014
12,346
Probably because you have a large capacitor across the output of the bridge rectifier. The ripple across that capacitor will be small.

#### Cyanners

Joined Jan 18, 2022
6
For starters your input power is 240 VAC(rms) * 1.75 Amperes = 420 Watts
Your output power is 500 Watts

YOU CAN'T GET MORE POWER OUT THAN YOU PUT IN!!!
The 1.75A is the ripple of the input current I believe and not the actual peak value of it.

#### Cyanners

Joined Jan 18, 2022
6
Probably because you have a large capacitor across the output of the bridge rectifier. The ripple across that capacitor will be small.
Is that capacitor not necessary to provide a proper DC input to the boost converter?

#### AlbertHall

Joined Jun 4, 2014
12,346
Have a look at this schematic
You will see that the capacitor following the bridge is just 0.1uF.

#### Cyanners

Joined Jan 18, 2022
6
Have a look at this schematic
You will see that the capacitor following the bridge is just 0.1uF.
Thanks for the info that is a useful link. Ill change around the circuit and try again. All other circuits ive seen of this design have some component that handles the switching signal. Is there a simpler way to do this with a current sensing resistor?

#### AlbertHall

Joined Jun 4, 2014
12,346
Active PFC is not simple and I am nobody's expert on it. Passive PFC is simpler but it needs a large iron cored inductor.

#### Cyanners

Joined Jan 18, 2022
6

I managed to get it a lot closer to what i want which is the current having the same phase and shape as the voltage. It has the general shape but there are huge spikes which i cant seem to figure out the cause of. Any ideas?

#### Ian0

Joined Aug 7, 2020
9,795
Where does your PWM signal come from?