Efficiency-optimized direct torque control of synchronous reluctance motorusing feedback linearization

In this paper, a nonlinear controller capable of high dynamic torque regula tion and efficiency optimization of the synchronous reluctance motor (SynRM ) using input-output feedback linearization is proposed. The cross-coupling effects in the SynRM model and the torque nonlinearity due to the iron los ses in torque-speed characteristics of the SynRM are discussed. The criteri on for the efficiency optimization is also introduced and investigated. Sin ce the proposed nonlinear controller directly regulates the torque by selec ting the product of d- and q-axes torque currents as one of the output vari ables, the nonlinear and cross-coupling aspects between the d-and q-axes to rque currents and the terminal currents can be eliminated, Hence, the linea r torque-speed characteristic can be achieved, In addition. by controlling the power loss-minimizing criterion directly, the proposed controller can o ptimize the efficiency of the SynRM without deteriorating the dynamics perf ormance.