How to calculate PI values when I apply Direct Torque Control in Induction Motor for speed controller?

I want to control an induction motor with direct torque control method. I need PI controller for speed control. I don't know how to calculate PI values.

Also, I want to apply and Direct Torque Control with Space Vector PWM, that I need three PI Controller for speed, torque and flux and I don't know how to calculate PI values as well.

Answer 1

[Anshuman]

Hi Giannhs,

To calculate the proportional-integral (PI) controller values for speed control of an induction motor using direct torque control (DTC), you can follow these general steps:

1. Determine Desired Performance Specifications: Define the performance requirements and specifications for your speed control system. This includes parameters such as speed response time, steady-state speed accuracy, and disturbance rejection.
2. Obtain Motor Parameters: Collect the necessary parameters of the induction motor, such as the motor's inertia, torque constant, and electrical time constant. These parameters are typically available in the motor's datasheet or can be obtained through motor testing.
3. Design the Proportional (P) Controller: The proportional term of the PI controller is responsible for providing a control action proportional to the error between the desired speed and the actual speed. The proportional gain, Kp, determines the strength of this action. Start by setting Kp to a relatively small value and gradually increase it until you achieve the desired response speed. Higher values of Kp will result in faster response but may introduce overshoot or instability.
4. Design the Integral (I) Controller: The integral term of the PI controller is responsible for eliminating steady-state errors and improving the system's response to disturbances. The integral gain, Ki, determines the strength of this action. Start by setting Ki to zero and gradually increase it until steady-state errors are minimized. Be cautious not to set Ki too high, as it may introduce instability or overshoot.
5. Tune the PI Controller: Once you have initial values for Kp and Ki, you need to fine-tune the PI controller to achieve the desired performance. This can be done through experimentation and iterative adjustment of the gains.
6. Validate and Test: Validate the performance of the PI controller by simulating or implementing it in your control system. Test the system under various operating conditions, including different setpoints, load disturbances, and speed references. Verify that the controller provides the desired speed control and meets the performance specifications defined in step 1.

It's important to note that the specific values of Kp and Ki will depend on the characteristics of your induction motor, the control system design, and the desired performance specifications. The tuning process may require some iteration and adjustment to achieve optimal results.

If you have access to a motor model or a simulation environment like Simulink, you can use it to simulate the motor and controller system to evaluate different PI controller values before implementing them in hardware.

Hope it helps!