DTC strategies dedicated to IM drives fed by reduced-structure inverters emulating the conventional one: Application to low-cost automotive actuators

Abstract

This work is aimed at the development of novel direct torque control (DTC) strategies devoted to induction motor (IM) drives fed by two reduced-structure three-phase inverters, such that (i) the four-switch three-phase inverter (FSTPI) also called B4-inverter and (ii) the three-switch three-phase inverter (TSTPI) also called B3-inverter or delta-inverter. The proposed strategies make it possible the emulation of the operation of the conventional six-switch three-phase inverter (SSTPI), thanks to appropriate combinations of the unbalanced voltage vectors intrinsically-generated by the reduced-structure inverters, leading to the synthesis of the six balanced voltage vectors of the SSTPI. Doing so, one can suitably implement the vector selection table introduced by Takahashi in the earliest-DTC strategy. The resulting high performance allied to crucial cost benefits make both FSTPI- and TSTPI-fed IM drives under the control of the proposed DTC strategies very attractive in large-scale production industries such as the automotive one.