Embedded Matlab function for Microcontroller modelling with PWM

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Hello!
I am modelling a solar tracking system in simulink, and i want to include an embedded matlab function with 'if' statements to represent a microcontroller. The inputs will be 2 values of voltage representing the LDR values, and within the matlab function i will compare the input values and create an output which will commmand a motor to rotate clockwise or counterclockwise. I have built the motor model in simulink, which will recieve an input voltage(coming from the microcontroller) and will output an angle of rotation. My question is what should be the output of the microcontroller? I think maybe the microcontroller could output a duty cycle of a PWM which will correspond to a voltage(maybe use a look up table) but i am not sure. I also want to include a PI controller but i am not sure were should be connected and what the error input should be. I want to model this operation as simple as possible because i am a beginner at electronics, and also the simulation time is very long,(10*3600s) so a complex system will make my simulation slow. Any response will be very helpful.
Thank you
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Eleni.T
Eleni.T on 30 Jun 2020
Thank you so much for the response, you 've been very helpful!
Yes my case is the last one you mentioned, and a Perturb&Observe algorithm would be a good solution i guess! As I have found in literature, the light sensors are represented with the following diagram (4 sensors for north-south,east-west sensing).
But as i dont know much about electronics in order to choose values for all the resistors etc, I think the perturb&observe algorithm will have the same results so i will try it! I have the two voltage values calculated as shown below and from that point i will continue with the P&O. If i am not mistaken it isalso cheaper to implement compared to the above circuit.
Thank you for the ideas.

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Accepted Answer

Mohsen Aleenejad
Mohsen Aleenejad on 30 Jul 2020
Hi Eleni.T,
The correct answer to this question really depends on your final design. What paramters are being controlled and what topology is driving the motor? (Type of the motor and Drive. Parameters: Position/Speed of the motor. Control algorithm: Speed Control/Torque and Direction Control, Current Limiting Circuit). If a general answer helps, then assume that you wanna control a dc motor position:
If you wanna increase the model accuracy and get closer to the real problem then:
The real world problem needs a very accurate system with more complexity.

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