Hybrid DTC induction motor approach

This paper describes a control scheme for direct torque and flux control (DTC) of induction machines based on the stator flux orientation method. With the proposed hybrid control scheme, an inverter duty cycle is calculated via Lyapunov stability issue each switching period based on the torque and flux errors. The direct method of Lyapunov is used to analyze stability of the system and an hybrid control strategy is designed from the analysis. In using the direct method, the idea is to construct a scalar-energy-like function (Lyapunov function) for the system and to examine the function´s time variation. The closed-loop system with the proposed control law not only guarantees a sufficient stability region, but also provides good transient response and good regulation in the induction motor output flux and torque. In this paper, a new control law based on Lyapunov stability theory, without linearization, is proposed that strictly guarantees a sufficient stability region in the state space for the system against large-signal disturbances. Simulation and experimental results are shown to validate the strategy.