# Where to find Single Phase Brushless DC Motor, or way of conversion

Discussion in 'Sensors and Actuators' started by BlueCerealBox, Sep 12, 2016.

1. ### BlueCerealBox

27
0
Sep 30, 2014
Hello,

This is my for final year college project. I'm currently trying to look for a single phase Brushless DC(BLDC) Motor, I've tried googling but couldn't find any. However, I was able to find many websites selling relatively cheap (Below 50 bucks) three phase BLDC motors. I do require my BLDC motor to rotate in both directions, but I don't want the trouble of dealing with the commutation of the three phase BLDC motor.

I intend to program my motor using arduino and a H-bridge IC as a speed controller.

Since I can't find any single phase BLDC motors online, is there anyway I can convert a three phase BLDC motor to a single phase one?

Thank you.

2. ### Alec_t

2,969
804
Jul 7, 2015
So how do you propose to reverse it? Simply reversing the supply voltage (i.e. by using an H-bridge) won't do it.

3. ### Minder

3,103
664
Apr 24, 2015
Although a BLDC motor is identical to a 3 phase PM motor it is reversed by changing the switching direction of the stator coils, of which only two of the three winding are switched at any one time.
IOW you require 6 switching devices not an H bridge, DC brushed motors use these method.
If you need a cheap motor to experiment there are BLDC RC motors, some are outrunners that revolve the outer rotor.
There is no such thing as a 1ph BLDC motor that I have come across, you require the phase angle provided by 3 stator coils.
M.

4. ### BlueCerealBox

27
0
Sep 30, 2014
Thank you for the replies. In that case I guess it would be better to just use a normal 3 phase BLDC motor. But how do I have to change the sequence of commutation to change the direction of rotation(CW or CCW) ?

5. ### Minder

3,103
664
Apr 24, 2015
You change the rotation or direction of the energized stator fields.
M.

6. ### BlueCerealBox

27
0
Sep 30, 2014
How would I go about doing that? I know that in terms of hardware, a BLDC motor will have 3 wires, usually the U,V and W wire. I'm only looking for cheap BLDCs under 50 bucks so I assume those will not have any hall sensors.

How will I change the sequence of commutation then? Can I just keep one wire connected to high and then alternate the other two to change the direction? Eg.Keep U connected to high, then use V and W to control the direction of rotation.

7. ### Bluejets

4,990
1,048
Oct 5, 2014
As Minder says, it needs 3phase ac. Perhaps a couple of interlocked changeover relays on 2 phases of the control module, which easiest would be say a hobbyking controller for maybe 10 or 15 bucks.

8. ### Minder

3,103
664
Apr 24, 2015
You need to build a driver, there are some dedicated IC's for this made originally by Motorola MC33030 etc and a few others.
You either need hall effect or sense current on power up and do a slight exercise of the motor to find the position of rotor.
If you go the RC route, there are a few DIY driver circuits out there. but you would have to modify to enable reverse mode.
You require all 3 conductors, for the 3 windings switching, the sequence for FWD would be 1&2 2&3 3&1 etc, for rev it would be 1&3 3&2 2&1 for e.g.
M.