Direct Torque Control of Asynchronous Motors

Direct Torque Control (DTC) of asynchronous motors is a high-performance motor control methodology. It employs vector transformation to convert three-phase motor parameters into two-phase quantities within the stationary reference frame (α-β coordinates). The key implementation steps include: 1. Clarke transformation for three-phase to two-phase conversion 2. Torque and flux estimation using voltage and current measurements 3. Hysteresis comparators for torque and flux regulation 4. Optimal switching table selection for inverter control This approach offers a simplified model structure with straightforward implementation logic, facilitating quick simulation outcomes. A notable advantage is its ability to autonomously adjust motor torque in response to load variations through real-time torque error minimization. Additionally, DTC contributes to reduced motor noise and vibration, thereby extending operational lifespan. For optimal control performance, proper selection of control parameters (hysteresis bands, sampling time) and comprehensive understanding of motor load characteristics are essential. The control algorithm typically involves: - Stator flux estimation: ψ_s = ∫(V_s - R_s·I_s)dt - Electromagnetic torque calculation: T_e = (3/2)·p·(ψ_α·i_β - ψ_β·i_α) - Sector identification for voltage vector selection - Switching state optimization based on torque/flux status