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Complementary drive from microcontroller

Discussion in 'Electronic Basics' started by Prasad, Sep 24, 2004.

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  1. Prasad

    Prasad Guest

    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
     
  2. Anand Dhuru

    Anand Dhuru Guest

    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
     
  3. Rich Grise

    Rich Grise Guest

    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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