24vdc motor pump

[cedax]

Hi everyone

I need to drive an 24vdc motor (3A) and modify the speed.

I thought of using the PWM output attached to a solid state relay.

It 's the right way or have any suggestions?

Thanks

[Simon]

In general terms that is the right approach. I have a small fan at my desk running directly off the PWM output, with speed varied by temperature. Had to juggle the frequency - too high and it made a terrible noice, to low and it shuddered. If the pump won't be near people, the whining of the PWM should not be a problem.

[Joe Tauser]

I have done this, and the PWM output works well. I found a frequency setting of 100 worked in my application. Also remember that the Duty Cycle goes from 0 - 1000.

Make sure you use a DC SSR, such as a Crydom D1D20. I realize this is a 20A relay, but it's only $10 more than the 7A unit and you get a lot more wiggle room. You won't need a heat sink at this low current.

Joe T.