Vector control methods for induction machines: an overview <s> A. Direct Quadrature Control Methods <s> New quick-response and high-efficiency control of an induction motor, which is quite different from that of the field-oriented control is proposed. The most obvious differences between the two are as follows. 1) The proposed scheme is based on limit cycle control of both flux and torque using optimum PWM output voltage; a switching table is employed for selecting the optimum inverter output voltage vectors so as to attain as fast a torque response, as low an inverter switching frequency, and as low harmonic losses as possible. 2) The efficiency optimization in the steady-state operation is also considered; it can be achieved by controlling the amplitude of the flux in accordance with the torque command. To verify the feasibility of this scheme, experimentation, simulation, and comparison with field-oriented control are carried out. The results prove the excellent characteristics for torque response and efficiency, which confirm the validity of this control scheme. <s> BIB001 </s> Vector control methods for induction machines: an overview <s> A. Direct Quadrature Control Methods <s> The sensitivity of the parameters of a rotor-flux-oriented system using rotor flux estimation is discussed, and a stator-flux-oriented scheme is developed. Since the estimation of the stator flux is independent of the leakage, the steady-state performance of the stator-flux-oriented system is insensitive to the leakage inductance. A decoupler is designed to minimize the coupling in the stator-flux reference frame, improving the dynamic performance of the system. Digital simulation is carried out to show that the performance of the stator-flux-oriented system is superior to that of a detuned rotor-flux-oriented system. > <s> BIB002
The general control scheme is presented in Fig. 3 . The PI regulators shown in this figure could be substituted by other classical or modern controllers. To decouple the torque and flux control loops, it is necessary to compensate for the term shown in Fig. 1 . As already shown with Fig. 2 , this decouple occurs naturally with the rotor-flux reference. In the general case, the decouple can be achieved by adding the term at the output of the flux controller, as shown in Fig. 3 , where BIB001 This term is obtained through the compensating block in Fig. 3 , using the values from the estimator block. An example of this method can be found in BIB002 . Again choosing the rotor-flux reference, the compensating term given in (6) will be zero since .