I recently purchased the Ardumoto shield from sparkfun (http://www.sparkfun.com/products/9815) to drive a small liquid pump. This motor is brushless (http://www.hargravesfluidics.com/pdf/LT … 0Sheet.pdf) and I know that there are differences driving a brushless motor. Everything I found said that brushless motors needed PWM control and an H-bridge. I thought that is what I had setup, but no go.
The power supply I am using is a 1.5A, 12VDC wall supply. I have a new Uno controlling things and have been using the supplied example code for the Ardumoto shield. Still no go.
What do I have to do to get the Ardumoto shield to drive a brushless motor? The motor spins just fine when connected to the 12V source.
Thanks!
Ryan
You’re trying to control a brushless motor with a driver for brushed motors. Ardumotor only works with brushed motors. Just to confirm, your motor has three wires, correct?
Fortunately all you need is an ESC (Electronic Speed Control) that would be used with an RC car/airplane/etc. Tower Hobbies, Hobby King, or any local RC store would have tons of them in stock. ESCs are controlled in the same way as you would control a servo, so the Arduino Servo library would make things pretty simple.
Chagrin:
Fortunately all you need is an ESC (Electronic Speed Control) that would be used with an RC car/airplane/etc.
That’s what I thought at first, but that pump is expecting a DC voltage (it has the motor drive circuit inbuilt). If you wanted to use a brushless DC controller, I think you’d have to rip open the pump to access the motor windings directly - probably not recommended.
What I think you need to do is drive it with an adjustable DC voltage to vary the speed. I’d suggest an adjustable switchmode voltage regulator chip, driven by a PWM pin on the Arduino (with some filtering to give a decent DC voltage level).
rbardsley,
FWIW, the [Ardumoto board is an H-bridge motor driver.
What makes you think you can run this pump at variable speed? I looked at the data and the Parker site and didn’t see any such claim. The pumps are available with motors for several different voltages, but that’s not the same thing as being subject to speed control by operating at less than the rated voltage.
Have you tried to run this pump with the Ardumoto board? If so, what happened?
Without knowing much more about the pumps electrical “innards”, I can’t predict what would happen. It may be that the Ardumoto can control the speed. It may be that you can do that, but only if you provide enough capacitance between the ArduMoto and the pump to smooth the power. It may be that the pump won’t run at all at less than full voltage.
Have you tried running the pump at a lower voltage? If so, what happened? If not, does the pump documentation make any mention of this? If not, have you asked Parker?
Happy Hunting,
Eric](http://www.sparkfun.com/products/9815)
My experience with brushless motors with integrated drivers (eg computer fans) is that they will quite happily run on considerably reduced voltage, and that this can be an effective method of speed control. Worth a try, particularly if you have an adjustable DC power supply you can do some initial testing with.
Hi everyone. Thanks for your help. It turns out that the pump I was trying to use was jammed. It was drawing full load from the start and the Ardumoto shield didn’t have anything to do with it. I tried a smaller pump that used a similar brushless motor (also from Hargraves/Parker) and it works just fine. I am using PWM to control the pump quite successfully. I have mapped the 0-255 to a 0-100 range so I can run in human-readable percentages. The motor works just fine from about 34% up to 100% using the Ardumoto shield. I am pretty sure the motor has some form on integrated circuit inside the small endcap. The pump was $220, so my guess is there is something fancy going on. I just don’t have time right now to investigate. If I come across anything, I’ll post my findings.
Thanks.
R