H-Bridge (Please check)

Discussion in 'General Electronics Chat' started by SVS, Nov 4, 2013.

  1. SVS

    Thread Starter Active Member

    Aug 16, 2012
    Hi everyone,

    I have roughly designed a H bridge circuit to drive an inductive load .I have attached a sketch with all the parts and its values.
    It would be really helpful if you could crosscheck the circuit and point out the mistakes.

    Circuit description:
    This circuit's switching frequency is between 30-50 KHz.
    The load is a step up transformer(inductive) and the reamianing information is in the attachment.The duty cycle of the PWM signal is 50 % and the MOSFETS M1,M4 and M2,M3 are alternatively switched considering the rise and fall time.

    Thank you in advance..
    Last edited: Nov 5, 2013
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    Depending on your load 1mF may not be sufficient. There will be quite some ripple voltage so make sure that at maximum load you still have enough DC voltage when AC passes through zero.

    If you want to drive a motor with that make sure it cannot work as a generator, like if you decrease the PWM duty cycle rapidly and the motor still turns. This could increase the voltage on the 1mF cap.

    I would personally not start right away with 300V. Start with low voltage, preferably with a power supply with current limit. Monitor the voltage drain source to observe possible voltage peaks. Depends very much on your layout. Place the big cap near the bridge, keep the bridge small, put the drivers near the bridge.
  3. SVS

    Thread Starter Active Member

    Aug 16, 2012
    Thank you for the response,

    even I thought of using a variable transformer to start with a small value and start increasing it gradually and check the voltage at every point in the circuit.

    my load is a step up transformer with a primary inductance of 0.4 mH.

    Is there someother major mistakes in my circuit ?
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
    If your load is a transformer, then is there really a need to drive both ends of the winding?
  5. SVS

    Thread Starter Active Member

    Aug 16, 2012
    It is similar to a resonant converter.
    Please see the attachment.
    tubeguy likes this.