marifhossain
Newbie level 4
dead time inverter mosfet controls
I designed a three phase inverter for a 48 volt 3 phase ac motor. What I did was I designed a small chopper for generating 4 slit power supplies. One split supply for the lower three IGBTs of the Three Phase MOSFET/IGBT bridge and the other three for the three high side IGBTs. I used AT89c2051 for generating the pulses for driving the high side and low side IGBTs and used PWM algorithm.
But one problem was there and a very nasty one was Shoot-through. MOSFETS/IGBTs bursted and short circuited the DC power source at the moment of starting the motor. I suspect that the problem was at the Microcontroller outputs of the AT89c2059 which are all 1 at the begining. So what I did was installed a Relay before the inverter line. The control circuit was enegised first and stable pulses was started and after a small delay time (1 sec or 2) the relay started and gave power to the inverter. This improved the stability of the circuit a lot and only once in a hundred times the IGBTs gone after that. But still I could not make it 100% ok.
I believe the Microcontroller "Hangs" while the Motor starts and takes heavy loads.
Now I want to design 400 volt inverter. But before that I would like to have some comments. If anyone of you have block diagrams or complete circuit diagram of any professional frequency inverter?
I am a microcontroller programmer and I can program SPWM algorithm to it but I need my inverter power circuit to be stable first. Any help from professional inverter designers?
I designed a three phase inverter for a 48 volt 3 phase ac motor. What I did was I designed a small chopper for generating 4 slit power supplies. One split supply for the lower three IGBTs of the Three Phase MOSFET/IGBT bridge and the other three for the three high side IGBTs. I used AT89c2051 for generating the pulses for driving the high side and low side IGBTs and used PWM algorithm.
But one problem was there and a very nasty one was Shoot-through. MOSFETS/IGBTs bursted and short circuited the DC power source at the moment of starting the motor. I suspect that the problem was at the Microcontroller outputs of the AT89c2059 which are all 1 at the begining. So what I did was installed a Relay before the inverter line. The control circuit was enegised first and stable pulses was started and after a small delay time (1 sec or 2) the relay started and gave power to the inverter. This improved the stability of the circuit a lot and only once in a hundred times the IGBTs gone after that. But still I could not make it 100% ok.
I believe the Microcontroller "Hangs" while the Motor starts and takes heavy loads.
Now I want to design 400 volt inverter. But before that I would like to have some comments. If anyone of you have block diagrams or complete circuit diagram of any professional frequency inverter?
I am a microcontroller programmer and I can program SPWM algorithm to it but I need my inverter power circuit to be stable first. Any help from professional inverter designers?