PM motor control

[automatic2]

Looks like the current/thermal qualities of a ua78xx regulator meets the needs of a small PM motor application. I'm thinking of directly driving the motor off the output of the regulator. I would need to add a variable output divider inbetween output-common as to adjust voltage for setup. Here's my query, anyone know a way of turning off the regulator without switching motor power?. Any other suggestions for simplicity sake?.

 

[sreid]

With three terminals you don't have a lot of choices. I think if you open the ground terminal the regulator will shut off. Try it, a 78xx is not a big loss if it blows up. Also, connect a power diode from input to output to make certain the output voltage is never larger than one diode drop above the input voltage.

 

[aolalde]

I understand that this voltage regulator normally energizes a Generator field exciter.

If that is the case, as the line voltage is constant, the VR will keep the output close to zero, since the VR will not sense requirements to increase the AC voltage.

 

[ScottyUK]

Hi aolalde,

The uA78** regulators are little three-terminal electronic regulators in a TO-220 package. I've never seen one on a generator field circuit, except buried within the control system power supply circuitry. Are we discussing the same thing here?




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If we learn from our mistakes,
I'm getting a great education!

 

[aolalde]

ScottyUK (Electrical)

Thanks for your explanation. I had no idea.