MATLAB Simulation Model of Direct Torque Control for Three-Phase Induction Motors

Direct Torque Control (DTC) represents a high-performance motor control methodology particularly suitable for three-phase induction motors. Compared to traditional vector control approaches, DTC achieves rapid dynamic response by directly regulating motor flux linkage and torque, thereby simplifying control architecture and reducing parameter sensitivity.

In MATLAB simulation models, the DTC system typically comprises the following core modules implemented through Simulink blocks and custom functions: Motor Model: Dynamic modeling using three-phase induction motor equations including stator voltage equations, rotor flux linkage equations, and mechanical motion equations, typically implemented through S-function blocks or Simulink's power system toolbox. Flux and Torque Estimation: Real-time estimation of motor flux linkage and electromagnetic torque through measured stator voltages and currents using integration algorithms (e.g., voltage model integration with DC offset compensation) and torque calculation functions. Hysteresis Comparators: Comparison of estimated flux and torque with reference values through hysteresis control logic, generating switching signals to maintain flux and torque within specified error bands using relational operators and state machines. Switching Table: Selection of appropriate inverter switching states based on hysteresis comparator outputs and flux sector determination (typically 6-sector division), implemented via lookup tables or conditional logic blocks. Inverter Module: Voltage Source Inverter (VSI) implementation using semiconductor device blocks (IGBTs/diodes) to provide controllable three-phase voltage output with pulse-width modulation capabilities.

The advantages of DTC include simple structure and excellent dynamic performance, though it faces challenges with significant flux and torque pulsations. In simulation models, control algorithms can be optimized through techniques like Space Vector Modulation (SVM) implementation or improved switching strategies using advanced modulation index calculations to reduce pulsations and enhance control precision.

MATLAB simulations enable visual observation of motor flux trajectories, torque response characteristics, and speed regulation performance through scope blocks and data logging. This facilitates control parameter tuning and algorithm validation through interactive GUI elements and script-based parameter sweeps. The model serves not only for academic research but also provides practical references for real-world motor control system design with code generation capabilities.