Field-Oriented Control with Simulink

Part 1: What Is Field-Oriented Control?

Learn more about field-oriented control:

Learn how field-oriented control provides high-performance torque or speed control for various motor types, including induction motor, permanent magnet synchronous machines (PMSMs), and brushless DC (BLDC) motors.

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The video introduces a typical field-oriented controller architecture and explains various components involved. Those include AC motor, power inverter, Clarke, Park, and inverse Park transforms, inner-loop current controller, optional outer-loop speed or flux controller, space vector modulator algorithm, and an optional rotor speed and position observer.

The video explains how Park and Clarke transforms are used to simplify computations by converting AC current and voltage waveform into DC signals. Continuous and discontinuous modulation schemes for space vector modulation are discussed.

Part 2: Modeling Motor, Inverter, and Controller

The video shows how to use Simscape Electrical to build a model that includes a squirrel cage asynchronous machine, a power inverter, voltage source, a power transformer, and a rectifier. The video explains how you can change parameters of various blocks in the model including motor parameters, switching devices in the inverter, and parameters of the transformer to customize the model for your application.

It demonstrates how phase currents and phase voltages can be measured from the model. It also shows how to model a mechanical load on the motor shaft. A proper choice of simulation solver is discussed to achieve the right balance of simulation speed and accuracy.

The video then explains how to model various components of a field-oriented controller. Those include proportinal-integral (PI) controllers for the inner current loops and outer speed and flux loops, Park and Clarke transforms, and space vector PWM generator, as well as an observer for estimating rotor position and speed.

Part 3: Automatic Tuning of Controllers for an Induction Motor

The control system consists of four PI controllers. The rotor speed and flux controllers in the outer loop provide references to the current controllers in the inner loop using the measured rotor speed and three-phase stator current as well as the Clarke and Park transformations. The four PI controllers are tuned using the Closed-Loop PID Autotuner block in a single simulation. This block injects an excitation signal during closed-loop plant operation to estimate the plant frequency response and automatically tune the PID gains. Based on the PID outputs, a PWM Generator module is used to generate the gate control pulses for the semiconductor switches in the machine-side power inverter, such that the desired flux and torque specifications are met. The Closed-Loop PID Autotuner block is part of Simulink Control Design™ since MATLAB® R2018a and the induction motor and power converters have been modeled in Simscape Power Systems™.

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