How does a sine choke exactly function? In most high power inverter systems, the primary side of the output transformer is always driven by a PWM signal. The secondary output which is sent to a load should also come out to be PWM. How does a pure sine wave inverter exactly convert this PWM into a pure sine wave? What if we fed SPWM directly to the primary of the ferrite transformer, how to filter the secondary output to get pure sine wave?
There are two possibilities:
1. HV DC, H Bridge (low current) -> PWM, LC filter removes switching HF and what remains is a sine wave.
2. Low voltage DC, H Bridge (high current)-> PWM, LC filter (high current), transformer iron core 50/60Hz; on secondary you get sine wave.
3. Low voltage DC, push-pull converter with ferrite transformer, HV DC output, same as point 1.
The ferrite choke is a part of LC filter for elimination the HF transistir switching frequency.