PMDC motor back EMF control circuit designing guidline
We are using PMDC motor in one of application and supply voltage is applly through rectifier bridge circuit to convert AC to DC.
When motor is operated on no-load condition, we noticed some additional voltage due to back EMF at the rectifier terminal which is almost 35% higher than the rated voltage.
If we are using 220vdc PMDC motor,
input at rectifier circuit = 220Vac
output at rectifier circuit = 210Vdc
But when the motor runs,
the output of the rectifier circuit = 300Vdc.
In such a case, the motor is rotating with inappropriate speed against rated speed.
This is obviously due to back EMF which needs to control by placing the additional circuit in parallel to the rectifier bridge circuit.
Suggest me an appropriate circuit to protect bridge rectifier or ommit back emf from motor.