Hey all,
I want to charge a battery from a three phase generator using the circuit attached.
Fast explanation:
When voltage reaches 14,4V mosfets will be closed and shunt the current back to the generator.
I want to have a fixed switch frequency so I made a simple sawtooth signal from three transistors (70Hz).
The first comparator is for comparing the 14,4V with reference voltage 2,5V from a TL431.
The second comparator is for making the PWM signal with the needed duty cycle depeding on the voltage in c3.
I build the circuit on a breadboard and it works pretty well but if I change the load the output voltage is also changing alot like 0,5V.
I want it to be less than 100mV.

Using a microcontroller would probably fix the issue but I am looking for an analog solution.

 

Generator or are you talking alternator, like in a car, since they are three phase AC that is rectified and and regulated?
Is your 'generator' permanent magnet or wound field?
Do you understand that most alternators or generators don't,

shunt the current back to the generator.

They control the field in a car alternator or shunt the output to ground like in a motorcycle alternator that has a permanent magnet field.

 

Generator or are you talking alternator, like in a car, since they are three phase AC that is rectified and and regulated?
Is your 'generator' permanent magnet or wound field?
Do you understand that most alternators or generators don't,
They control the field in a car alternator or shunt the output to ground like in a motorcycle alternator that has a permanent magnet field.

Thanks for your reply, I fixed the issue by adding a low pass filter in the voltage measurement.
It's permanent magnet.

 

You do know that not shunting the excess voltage to ground will burn up your stator don't you? This is why auto type alternators use a wound field, they control the magnetism and that then controls the output.