sensorless brushless 3 phase motor position control ??

[capacitor1]

hi

please can any one give me some solutions (ic , circuits ) about controlling the position of a sensorless bldc motor

thank u very much

 

[HTA]

You would need an encoder which generates already UVW signals or calculate from the absolute position(see ) or you take the sensorless approach using software in the motion controller.

Enjoy your design work!

 

[capacitor1]

Hello Mr HTA

thanx for you reply.
u said that the control of position will be by an encoder, but the problem is in the sensroless bldc that can't (according to the application notes) be rotates with a speed under 100 RPM = 1.6 RPS !!
so how can i control this bldc with a min speed = 1.6 RPS
so ....?

thanx HTA

 

[HTA]

Hi capacitor1,

the sensorless a BLDC motor based on back EMF has a problem at low speed. The only way is to add an additional sensor outside or modify the motor and build a magnetic encoder pcb inside( like described here: **broken link removed** ).
Do you have access externally to the motor axis to add a position sensor in some way?

Enjoy your design work!

 

[capacitor1]

Hi Mr HTA

Sorry for being late

My goal in my project is to do a gimbal brushless motor 2 axis.

the board used by the engineers contains micro,gyros, accelerometer and (L6234d). this IC is for sensorless brushless motor control .

My question is how they can control this accurate gimbal brushless motor, is the gyro the feedback or the accelerometer???

thanx Mr HTA

 

[HTA]

Hi capacitor1,

the sensorless driver software runs on the micro does not provide accurate position at low speed. To incorporate the actual position this driver software need to be changed to run position drive at low speed. Maybe you can drive the motor as a stepper and use the gyros or accelelerometer as a feedback. But this also requires a change in the sensorless driver software.
If the gimbal motor is of this type: **broken link removed** you might be able to glue a magnet onto the rotating axis in the back and then position a small PCB with the single chip encoder to output the position. But again the software need to be changed.

Enjoy your design work!

 

[capacitor1]

Hi HTA

About the gimbal brushless motor , is it a stepper motor or what , normal brushless motor ???

 

[HTA]

Hi capacitor1,

it is a high torque motor with high number of poles and driven by PWM. Here are more details: **broken link removed** .

Enjoy your design work!

 

[capacitor1]

Hi HTA

Thanx very much for your help