As so many posts state, Arduino newbie here. I am assessing options to provide basic control of a 1/4 HP PMDC motor.
Current solution uses a PWM control board rated for 4A at 120 VAC input, DC output. This board is controlled via a 5k pot. Ideally, I'd like to either replace the pot and use Arduino to master the control board, or identify an alternative means to provide speed (only, no direction) control of the 2.8A @ 90 VDC rated PMDC motor from Arduino.
I have looked through both the site and forum, and have seen only control of low-voltage DC motors, plus one instance of Arduino controlling a digital potentiometer. Not sure if the latter would prove viable as a replacement for the current manual pot.
Any comments or experience would be greatly appreciated!
Well 1/4 hp at 12vdc is around 16 amps. This is well within the capacity of using large logic level MOSFET switching transistor(s). This would allow the Arduino to drive your motor using it's PWM output pins. You need to know how you want to control the motor, variable speed would require some form of rpm sensor to feed back the speed measurement to the Arduino. If you just want on and off control then just using a simple digital output pin would be simpler yet.
As far as interfacing the existing motor drive board, the ones I've seen that used a pot to control speed also had an option to instead supply a 0-10dc control voltage input. That would not be as simple to drive with an Arduino without additional op-amps to gain the needed voltage range. As far as using digital pot to interface the exisiting controller, I have no experience with those devices, should work in principle but you are pretty much on your own to experiment with that.
I need to run this motor for continuously variable speed based on user (manual potentiometer) input. Ideally, I would like to continue using the current motor, rated for 90 VDC (30% form factor... to ~120 VDC), as opposed to moving to a 12VDC motor and separated power supply.
One additional factor... speed control is proportional, but not exact. Turn knob up a little, motor goes a little... but it doesn't need to rotate exactly 500 RPM at setting "5" or whatever.
One thing you could try is to work out if your motor controller is using the 5k pot (a standard electric vehicle throttle pot) simply to make a 0-5V voltage signal. You could connect a voltmeter to the pot's wiper and measure the voltage there. It might work backwards, i.e. 5V might represent "stop" and the motor will speed up as the voltage goes down! This is for a fail-safe mode in EVs.
Is it a Curtis motor controller, by any chance? Or do you have a make/model number for it?
If the controller can be driven by a 0-5V analog signal, then a PWM output, plus a simple filter circuit, should be able to drive it.