i'm doing a project on PID control (both speed & position) of a Brush less DC (BLDC) motor

i'm having a hard time in finding out the transfer function of BLDC motor

Could anybody plz give me the transfer function of Brush less DC (bldc) motor as soon as possible !

Is it same as that of for armature controlled commutated DC motor?

 

I have a paper with that transfer function.
E-mail me and I'll forward it to you.
Tom
Thomas B. Bullock, President
Industrial Controls Consulting Div.
Bull's Eye Marketing, Inc.
104 S. Main St., Suite 320
Fond du Lac, WI 54935
Ph: 920: 929-6544
Fax: 920: 929-9344
E-mail: [email protected]

 

Modeling DC (trapezoidal or 6-step) brushless motor is not that trivial and much more interesting than DC brushed motor.

My advice is to model DC brushless as a variable structure system: one structure is on commutational interval as all 3 phases are conducting; another one - on interval between commutations that is a normal operation with 2 phases in conduction.

Understanding DC brushless commutation allows to explain commutation related phenomena:

- current (torque) ripple – in the absence of current loop, current (torque) drop at the beginning of commutational interval is as much as 50%;
- the role of current loop in current (torque) stabilization on commutational interval;
- current sensing scheme impact on current (torque) ripple;
- current shaping at low and high speed, in motor and generator modes;
- torque-speed curves and the effect of phase advance on torque-speed area enlargement;
- why serial chokes cause motor torque loss at high speed;
- how to minimize motor current (torque) ripple in the absence of current loop by a suitable PWM pattern;
- how to stabilize motor current (torque) in the absence of current loop by feedforward technique and more.

Hope it helps.
-Alex
[email protected]

 

Can you help me to obtain the transfer function of a generator with excitation current as input and voltage as the output under no-load