If you are looking to control a sensorless BLDC motor, then you might want to try the DRV11873 from Texas Instruments.
I ran a few tests using the evaluation module and I was pretty happy with the results and how easy was to use it.
TI offers a free sample of the chip so it'll be great if it is adapted onto a shield for the Arduino.
It seems to be limited to BLDC motors with a common lead and upto 1.5A,
which I presume is disk-drive spindle motors and similar?
You presumption is correct.
If you need more power, then the drv8332 is a better alternative.
I attemt to drive a COBRA 2206 Brushless DC motor (3Phase) with a board (Chinese E-bay sourced) based on TI DRV11873 and ran in some problems:
When powering up the driver module, regardless of the PWM frequency and duty cycle applied to the DRV11873 chip, the motor does some short steps (presumably as startup seqeunce) and then holds at stand still. I presume this is becasue the DRV11873 does nto properly detect the phase of the motor and then stops due to over current protection.
I tried to connect a virutal ground with 3 10k resistors in Y connection at the COM input of DRV11873 (same result) I also tried 1k resistors for the Y connection to COM, but no improvement.
The board comes with a CCW / CW jumper. Changing its position changes the direction of the few "jumps" after power up, but otherwise the result remains the same. Removing the jumper all together does also result in the same.
Any suggestion what could be wrong or if this driver component is generally not suitable for the motor would be apreciated.
The motor specs are as follows:
Cobra CM-2206/20 Motor Specifications
Number of Stator Slots
12
Number of Magnet Poles
14
Motor Wind
20 Turn Delta
Motor Kv Value
2100 RPM per Volt
No Load Current (Io)
0.85 Amps @ 10 Volts
Motor Resistance (Rm) per Phase
0.098 Ohms
Motor Resistance (Rm) Phase to Phase
0.065 Ohms
Maximum Continuous Current
25 Amps
Max Continuous Power (3-cell Li-Po)
280 Watts
Max Continuous Power (4-cell Li-Po)
370 Watts
Motor Timing
5-10 degrees
PWM Frequency
8-20 KHz
You're trying to run a 25A max. motor with a 1.5A max. driver. What do you think?
Unless you have some really special requirements why not just use one of the many cheap 25/30A ESCs around that will easily run that motor?
Steve