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Dynamic brake for power door

  • US 6,175,204 B1
  • Filed: 11/25/1998
  • Issued: 01/16/2001
  • Est. Priority Date: 11/25/1998
  • Status: Expired due to Term
First Claim
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1. A dynamic brake for a power door which is moved by an electric motor, such motor having at least a first motor terminal and a second motor terminal, such motor being energized by a pulse width modulated H-bridge amplifier connected to a first power line having a first voltage and a second power line having a second voltage, such second voltage differing from such first voltage, such H-bridge amplifier including a first switch connecting such first motor terminal to such first power line and a second switch connecting such second motor terminal to such first power line and a third switch connecting such first motor terminal to such second power line and a fourth switch connecting such second motor terminal to such second power line, said dynamic brake comprising:

  • a brake control signal generator connected to receive an input signal indicative of a need to apply said dynamic brake, said brake control signal generator including at least one output signal line having a signal connection to a control input of such first switch and to a control input of such second switch, said brake control signal generator responding to such input signal indicative of a need to apply said dynamic brake by supplying at least one control signal to such control input of such first switch and to such control input of such second switch so that such at least one control signal causes such first switch to be closed and such second switch to be closed so that such motor is shorted through both such first switch and such second switch, thereby allowing a braking current through such motor driven by an emf of such motor and hence dynamically braking such motor, wherein said at least one control signal consists of pulses which are sequentially disposed in time, said pulses being pulse width modulated to limit a time averaged value of said braking current through said motor to a predetermined current value, said brake control signal generator further including means for communicating said control signals to such first switch and such second switch whenever such power door is closed so that said dynamic brake provides a force opposing opening of such power door; and

    a first series RC circuit connected in parallel to said first switch and a second series RC circuit connected in parallel to said second switch to prevent voltage spikes due to interruption of said braking current.

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