Introduction
Field-Oriented Control (FOC) is a technique used to control AC motors by managing their torque and magnetic flux separately. This is done by converting the motor’s currents into a reference frame that rotates with the motor’s magnetic field. It maximizes motor efficiency and enables higher speeds that are often non possible with other control methods. Additionally, FOC takes advantage not only of magnet torque but also reluctance torque.
FOC modeling in Simplorer
Setting up the model in Simplorer involves defining a battery, an inverter block (or individual transistors), current sensors, a motor block with the corresponding load and position feedback.
Additionally, the control logic needs to be defined. In this model, a basic FOC structure was modeled using Park and Clarke transforms, a Space Vector Modulation block and two PI controllers.
The model is parameterized, meaning the parameters can be modified by simply changing the values of the defined Simplorer variables. This can help tune the PI control easily, or adapt the model to simulate a system with different parameters.
Simplorer has a native Space Vector Modulation block, which was selected and set up for the simulation.
Motor RPM is also displayed in the simulation, and used to debug the model.
Finally, the system is adapted to run in Field weakening, by commanding a negative d-axis current, achieving a significantly higher rpm with the same load.
