Induced EMF
Induced EMF
(OP)
Is measuring induced EMF in a 12 VDC PM motor a good way to measure motor performance? I have sketchy info for now, but we have a customer using a 12 VDC PM motor with voltage dropped down from a 24 VDC system. Brush life has dropped from 1000 hours to less than 100. Improvements were made to the brush holder card by increasing the brush clearance and the coiled spring pressure. The brush shunt was changed from a side to rear mount to prevent the shunt catching on the BHO slot.
What is a simple way to measure back (induced) EMF?
What is a simple way to measure back (induced) EMF?





RE: Induced EMF
RE: Induced EMF
In field testing one regulator failed. The customer is concerned that the motor could generate enough back EMF into the regulator to damage it. The motor is only rated at 2 A. with 14VDC applied. I don't believe that this is the case. The customer did say that a power MOSFET was fried in the regulator. They did not know the condition of the motor.
RE: Induced EMF
You're now running way more current through the windings and the brushes. At the minimum, you're running at least double the current, which means 4 times the power.
The chopping of the 24VDC potentially means that you are cutting the voltage in the middle of a commutation. Won't there be a sizable inductive EMF generated? Normally, wouldn't the inductive EMF show up after the brushes have commutated to the next winding? But if you're chopping asynchronously, then you'll have inductive EMF generated while the brushes are still on the same winding.
TTFN
RE: Induced EMF
RE: Induced EMF
I would check the free wheeling diode first. Seems to be faulty (the transistor was fried). Or is it missing?