Brushless DC motor - Sinusoidal drive

[Champion78]

Hi,

I am a newbie to motor control and would like to find some articles on driving brushless DC motor with sinusoidal voltage. Could someone place point me in the right direction? I will be using hall sensors for position sensing.

Thanks alot.

 

[jbartos]

Suggestion: Visit

http://www.semicon.toshiba.co.jp/eng/solution/mtele/moter/buirasiresu.html

http://www.motionshop.com/pr/copley399.shtml

etc. for more info

 

[avigodner]

There is a common spread terminology misunderstanding for permanent magnet (PM) motors. Many people use DC brushless for trapezoidal (or 6-step) current control and AC brushless for sinusoidal control. For trapez control, PM bushless motor winding may be distributed so as to assure that phase-to-phase back EMF (torque) function is flattened - rather trapezoidal than sinusoidal. This reduces torque ripple that may be essential for low speed operation.

For PM motor commutation, one needs position sensor unless it is a (low cost or temperature / external magnetic field sensitive or whatever) sensorless application.

Coarse (60 el.deg resolution) Hall sensors are used to make trapezoidal commutation. For sinusoidal one, you need accurate position sensor like optical encoder or resolver.

This way, Hall sensors basically mean trapezoidal commutation. As you mention them in sinusoidal commutation context, I have to assume that you are talking about start-up (power-up) of sinusoidal drive with incremental encoder. The problem is that absolute position is not available from incremental encoder. Therefore, Hall sensors are used for initial coarse commutation unless absolute zero position is found.

For such an application, Hall sensors may be eliminated by using a kind of phase search procedure (see Smart Initialization article overview at

http://www.drbrushless.com

for more info).

 

[jbartos]

Suggestion: The previous posting link appears to be somewhat advanced, and covers the relatively new technology using H-bridges for motor control.

 

[nbucska]

There are brushless/sensorless spin circuits e.g. by Philips
TDA5144 etc. Sinusoidal voltage is not necessary but
you can approximate it with Pulse Width Modulation.



<nbucska@pcperipherals.com>

 

[SERVOCAM]

Hall effects for positioning will give you poor resolution (since there are usually only 3 HEDs). HED's are used for rotor position reference for commutation then switch to encodere (for sind drives, trap drives use only the halls to commutate). Consider Encoder.

Rather going into details (bit lazy today) go visit here:

http://www.motionvillage.com/training/handbook/

Kollmorgen did a good job publishing some info online.



Cameron Anderson - Sales & Applications Engineer
Aerotech, Inc. -

http://www.aerotech.com

&quot;Dedicated to the Science of Motion&quot;