Control systems always need feedback. If you want to control motor speed, you need it to be fed back so as to control optimally. You can use any mathematical forms, but, they usually use controller transfer functions. Then, according to their own criteria, they optimize the control system coefficients.
ibrahim03 said:What you said is right but my problem is that I dont know anything about the transfer function of the controller which is built into the motor. I have to design a feedback control system which regulates the speed of the motor according to the load on it. Also i have to model my design in Matlab. How can i do that when i dont know the actual transfer function of the motor and its in built circuitry.
Your BLDC already has electronics with speed control. Speed will be independant of load untill maximum is reached. To model it, you have to measure it. Data given in data sheet does not give nowhere near information about system behaviour, as you already concluded.
Sweep input with various frequencies and amplitudes and under various loads including various amplitudes of steps. By measuring frequency, amplitude and phase on monitoring output you can measure frequency, phase and step response of your system. Then from your data you can try to model it and fit it under curve that is satisfactory for desired tolerance.
That's identification toolbox, right?ibrahim03 said:What if I treat the motor as a black box system ? There is a toolbox in matlab which can be used to find the transfer function of a system by input and output data. How would that be ? any suggestions ?
Pramod-chavan said:hi sir,
I am also facing same problem to find the Transfer function of position controller system using a BLDC motor and feedback is a encoder.
if you know how to find the transfer function of a position control system please help me.............
mail: pramod.syscontrols(at)yahoo.in
regards
Pramod
Sorry for my mistaking what you want. If you want, I can send you some presentation material that I made several years ago. I have just translated it into English for you. Just give me your e-mail address. I wonder if this material will be helpful to you.
Added after 16 minutes:
The contents of the presentation material is as follows:
Title: Control System and MATLAB
1. Mathematical Models of Physical Systems (MATLAB and Simulink used)
2. System Modelling
State-Variable and Output Equations
Transfer Function
State-Space Form
MATLAB Representation in An M-File
3. PID Control using MATLAB
Open-Loop Step Response
Proportional Control
Proportional-Derivative Control
Proportional-Integral Control
Proportional-Integration-Derivative Control
4. DC Motor Speed Modeling
Physical Setup and System Equations
MATLAB Code using Transfer Function
MATLAB Code using State-Space Equations
5. PID Design for DC Motor Speed
Controller Transfer Function
Design Goals
MATLAB Code
Optimized Result
6. Modeling DC Motor Position
Physical Setup and System Equations
Design Goals
MATLAB Code
Optimized Result
7. PID Design for DC Motor Position
Controller Transfer Function
Design Goals
MATLAB Code
Optimized Result
I had made this material from the resources in the internet. But, now I cannot remember the sites.
Sorry for my mistaking what you want. If you want, I can send you some presentation material that I made several years ago. I have just translated it into English for you. Just give me your e-mail address. I wonder if this material will be helpful to you.
Added after 16 minutes:
The contents of the presentation material is as follows:
Title: Control System and MATLAB
1. Mathematical Models of Physical Systems (MATLAB and Simulink used)
2. System Modelling
State-Variable and Output Equations
Transfer Function
State-Space Form
MATLAB Representation in An M-File
3. PID Control using MATLAB
Open-Loop Step Response
Proportional Control
Proportional-Derivative Control
Proportional-Integral Control
Proportional-Integration-Derivative Control
4. DC Motor Speed Modeling
Physical Setup and System Equations
MATLAB Code using Transfer Function
MATLAB Code using State-Space Equations
5. PID Design for DC Motor Speed
Controller Transfer Function
Design Goals
MATLAB Code
Optimized Result
6. Modeling DC Motor Position
Physical Setup and System Equations
Design Goals
MATLAB Code
Optimized Result
7. PID Design for DC Motor Position
Controller Transfer Function
Design Goals
MATLAB Code
Optimized Result
I had made this material from the resources in the internet. But, now I cannot remember the sites.
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