Complementary drive from microcontroller

Sep 24, 2004 2 Replies
P

Hi,



I'm working on a project to construct a sine-wave inverter. The switches on the output side are 4 IGBTs connected in H-Bridge configuration. The IGBTs are right now driven by Mitsubishi M57962L drivers. I've managed to acquire a microcontroller which gives the required sine-wave PWM pulses at a switching frequency of 20kHz.



Now my problem is the interface the microcontroller to the IGBT driver. How do i `split' the single PWM pulse in complementary pulses to drive the high-side and low-side IGBTs??



I've heard there are ICs available that do the job. Someone suggested UC3714. I've gone through the datasheet, and i feel its not the one i'm looking for (or maybe i haven't understood the data properly?).



Can anyone suggest any solution??.



Reg., Prasad



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A

Hi Prasad,

Why not just pass the signal through 2 inverters in series (like the

7404 / 7414, six inverters in a 14 pin dip)? The output of the first would give you the complement of your original signal, and the output of the second would be your signal again.

Or am I missing something here?

Regards,

Anand

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R

On Friday 24 September 2004 10:25 pm, Anand Dhuru did deign to grace us with the following:

I think he's driving an H-bridge, and doesn't know about dead time yet.

You really need four waveforms:

__________ __________ __________ A ____| |________| |________| |_______ ____ ________ ________ _______ B |__________| |__________| |__________|

________ ________ ________ C _____| |__________| |__________| |________ _____ __________ __________ ________ D |________| |________| |________|

Where A drives the left-hand high-side P-channel gate, B drives the right-hand low-side N-channel gate, C drives the left-hand low-side N-channel gate, and D drives the right-hand high-side P-channel gate. (or change "P-channel" to "PNP", "N-channel" to "NPN", and "gate" to "base.")

The dead time ensures that you don't short out the supply. :-)

Cheers! Rich

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