Your main problem here is the supply for the signal processing - the sinewave goes below zero and you have no negative supply.Thank you for your response , it mean that without microcontroller it will be vary much difficult for 3 phase inverter designing using SPWM but 1-phase it can be done with proper filter designing?
I tried to design a spam using op-amp mostly, a square wave to triangular wave generator and comparing a sine were using comparator but my output of inverter was of a half were inverter. Were am I going wrong.? Please suggestView attachment 237179View attachment 237178
1) What problem are you trying to solve by using a 3-Phase Topology ?
2) What is the purpose of having a 3-Phase SMPS ?
3) Are you trying to control a 3-Phase Motor ?
4) Are you trying to reduce Power-Supply-Ripple-Voltage/Current ?
5) Are you trying to reduce the size of the Filter-Components ?
1. I am not working on 3 phase inverter for now… firstly i was asked in an internship interview to design an inverter whose supply is DC 400V and fundamental 50hz output has a rms voltage output is 90 per, and I don’t have to use any transformer or filter at end.
2. Single phase motor.
3. For now 1-phase motor.
4. Power supply ripple control was not asked so better to avoid it here .
5. Asked in interview is 90Per fundamental…so definitely a case of overmodulation and square wave inverter…i think so.
Where I can find all the maths and details ( all theory ) any reference will also be helpful.As I was making this Schematic in my head, it evolved, several times.
Several basic changes were made, and I was to lazy to spend the time to change them.
Now that all the SiC-FETs are the same part, it makes much better sense to change it.
It would further reduce the total RDS-ON,
but it would also require a second High-Current FET-Driver,
and a slightly different part number, one with an "Enable-Pin".
The Schematic is just to show the concept,
it hasn't had all the details and all the Math worked-out.
Maybe I'll fix it if I have the time, and if there is some interest in it.
Finding problems in other peoples work is a good thinking exercise.
Thanks for pointing it out.
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by Jake Hertz
by Jake Hertz