let me make very clear to you , i need conversion from DC to AC.
It is not possible to convert 320 DC to 230 AC by using rectifier we need inverter mechanism for that.
one common method is use H-bridge drive driven by 50 hz and connect bulky iron core transformer and just convert which i don't want .
other is 320 DC is chopped with 20 khz fed to mosfet and to ferrite core transformer and get 230 AC (high frequency) out , same method i need to use but needs output 50 hz-60hz only .
yes the same i need to use , but i can use only high frequency transformer (Ferrite /Toroidal) .
so need to drive H-bridge with modulated SPWM at 20 khz
and my question is how to get 50 /60 Hz from output ?, Is there any filtering mechanism without
creating much load .
You need to use a base frequency of 20kHz -50kHz and use PWM to modulate that at 50/60Hz.
Your transformer need to be designed for 20kHz-50kHz operation and not 50/60Hz.
No need to rectify the output but use a low pass filter to remove the baseband frequency. If you are using a centre-tapped secondary, ground the centre tap.
This is how radios work. Feedback control will be tricky but possible.
No need to rectify the output but use a low pass filter to remove the baseband frequency. If you are using a centre-tapped secondary, ground the centre tap.
This is how radios work. Feedback control will be tricky but possible.
If the base frequency is 50kHz and the modulation is 50Hz, you can very easily remove the carrier with a small power inductor and that may have only a marginal effect on the load.
A real design needs meaningful calculations at every stage.
This schematic portrays the usual method using a full H-bridge with SPWM.
Notice my screenshot shows clock 'A' switching rapidly. Switch D conducts during this half of the cycle.
B & C are off right now.
The switches are replaced by transistors or mosfets in real life.
The L & C create a second-order low-pass filter. This is the type commonly used to smooth SPWM. My values are suitable for a 1200 Hz carrier and 50 Hz fundamental.
The load gets AC sinewaves.
Notice the inductor must handle several Amperes, even though the final load is about 500 mA.
If the load is inductive or capacitive then it affects power factor. If this creates an error which causes a problem, then you need to consider how to correct it. If you don't then your load tries to draw current at wrong times in the AC cycle.