# 3 phase BLDC motor

Discussion in 'The Projects Forum' started by gusmas, Aug 31, 2012.

1. ### gusmas Thread Starter Active Member

Sep 27, 2008
239
0
Hi

My uni has a spare 3 phase BLDC motor but sadly the guy that was working with it left the uni with all the paperwork regarding it. Now i found the datasheet on the internet so that was a big help.

I have no experience with BLDC motors and before I start designing anything I would just like to switch on the motor and measure the hall effect sensor outputs. Now I dont want the motor to move or anything so I am not planning to provide any signals to the three phase inputs of the motor. The motor however has 3 outputs for the 3 hall effect sensors, a VCC for the hall effect sensors and then 2 temperature outputs.

Now my plan is just to supply VCC for the halls and the ground. Then take a oscilloscope and measure the outputs from the halls and temp sensors. By not supplying any signals to phase1,2 and 3 should not harm the motor in any way correct?

Attached is the datasheet for the motor.

I have the 167132 model.

Thanks

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2. ### shortbus AAC Fanatic!

Sep 30, 2009
6,282
3,647
The Halls are position sensors. So one, two, three or none of them may be on when shaft is static. They will turn on and off as the shaft is rotated. Just supplying voltage to the Halls should not hurt a thing.

3. ### donpetru AAC Fanatic!

Nov 14, 2008
185
27
Current drawn by each motor winding is:
Ic = Pn / (sqrt_3 * U * cosFI) where "cosFi" is played power factor relationship:
cosFi= (s*Omega1*M)/3*U2*I2.
where: s = motor slip; Omega1 = stator angular velocity; M = torque; U2 and I2 = current and voltage of the motor rotor.
I'll miss "cosFi" to not complicate the calculations.

So, the current drawn by each motor winding will be:
Ic= 400 / (1.73*48) = 4.81 A

Engine you can also feed a circuit circuit below, where continuous voltage will be redressed at least 1.73 * 48 = 83Vdc.
After feeding, only then treating the problem sensors: halls and heat.

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