harsh
Member
- Location
- aurangabad,maharasthra,India
I wanted to can the braking methods of an induction motor be applied to a servomotor.
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DIFFERENCE IN BRAKING TECHNIQUES WIT MOTOR
- Thread starter harsh
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Presumably you are asking what techniques are available for braking a servomotor.
They are pretty much the same as with an induction motor. You can do it electrically, via load friction, via a friction brake on the motor shaft, or some combination of all three.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
For the electrical option, would shorting the leads, bridging the leads with resistors and applying DC braking voltage all work for a servomotor?
mike_kilroy
Senior Member
- Location
- United States
1rst 2 yes, 3rd no.
I assume by servomotor OP means one with permanent magnets. As such, it has its own magnetic field so no 'DC injection' braking is ever used as it is not required. Most servomotors rotating at ANY speed can be shown to stop themselves in 2-3 REVOLUTIONS if leads shorted together. Obviously put an inertia load on it and it will take longer.
Reason for resistors in series is to get slower decel (longer stop time) due to A) application that requires it, or B) protect the motor. Most PM motors have a max current limit due to brush limitations or demag limitations. So a resistor may be required to limit the current - this is easily calculable.
But like vfd drives, servo drives should come with their own braking built in. Like a vfd, the v/hz is maintained, so stopping under drive control is a matter like in a vfd of reducing voltage and freq along this line. Like an induction motor, when decelling, the motor becomes a generator and pumps energy back to the drive. Like a vfd, the servo drive has dc bus voltage sensing and DB resistor to dump the excess energy.
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