DC motor braking

Discussion in 'General Electronics Chat' started by Dritech, May 19, 2014.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Hi,

    I am using two BTS7960 half-bridges to form an H-bridge. Is it safe to apply motor brake by turning both drivers on? Will it cause damage to the drivers or to the motor?
    Also, which is the best method for braking the motor, driving both terminals to ground or to Vcc (12V) ?

    Thanks in advance.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    It depends on the energy to be dissipated that is generated by the over running motor, RPM/load etc.
    You would have to turn on both low side or high side switching devices.
    If there is current detection in place you could control the rate or degree of braking.
    Max.
     
  3. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Thanks for the reply MaxHeadRoom.

    So how do I determine if it is safe to apply brake to the motor using the H-bridge?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    To establish an accurate reading you would normally either have to do empirical tests or gauge it from the motor maximum RPM, e.g. if you had a load of any kind and the motor was at maximum rpm which equated to maximum DC voltage, at this point the back EMF would be approximately equivalent to the supplied DC, so at the time of braking this energy would be placed across the two switching devices, this would continue as long as it took to bring the load to a stop, which although usually very rapid can be a fairly high degree of energy for however a brief moment.
    Max.
     
  5. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,281
    1,231
    Nice IC.
    It has current limit so it would seem to be ok to use it as a dynamic brake. It looks like the high side switches can handle the most current so I would use them.
     
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