Modified Strategy of Direct Torque Control
Applied to Asynchronous Motor
Based on PI Regulators
Soukaina El Daoudi
(&)
, Loubna Lazrak, Chirine Benzazah,
and Mustapha Ait Lafkih
Laboratory of Automatic, Energy Conversion and Microelectronics (LACEM),
Faculty of Sciences and Technology, University of Sultan Moulay Slimane,
Beni Mellal, Morocco
soukainaeldaoudi@gmail.com
Abstract. Direct Torque Control (DTC) is known to generate a fast and robust
response in asynchronous engines. Yet, during steady state, observable flux,
torque and current pulsations arise. This paper presents a study of modified
direct torque control applied to a three-phase high performance asynchronous
motor. The proposed strategy is based on PI regulators instead of the hysteresis
comparators to control both the stator flux and torque whose parameters are
determined from modulus and symmetrical optimum criterions. Since the per-
formance of a feedback control system relies on the accuracy of the response
signal, an estimator of stator flux and torque is presented. The control system
benefits from the advantages of field oriented control (FOC) and conventional
direct torque control (DTC) while avoiding some of the disadvantages of either
of the two control methods. Performances of the asynchronous motor control are
checked by simulations under MATLAB/SIMULINK software.
Keywords: Modified DTC Á Conventional DTC Á FOC Á
Asynchronous motor Á Modulus criterion Á Symmetrical optimum criterion Á
PI regulator Á Torque/Flux estimator
1 Introduction
The three-phase asynchronous motor is the most used electric motor worldwide for
industrial applications. Simple in terms of design, robust and economical to use. It is
the most promising drive solution at the level of low cost and high quality. Due to those
advantages, numerous efforts by researchers have been made to develop the strategy of
control for this type of electric motors. Among those strategies; there is the vector
control strategies which consist of field oriented control (FOC), direct torque control
(DTC), etc. In general, the vector control methods were based on the same idea that
transforms the motor ’s three phase variables into two phase variables to separate of the
motor parameters as flux-component and torque-component [1]. In the same way, the
FOC is a strategy that assigns high performance and quick dynamic response over a
wide speed range to asynchronous motors by decoupling their variables; but it uses a
rather high number of regulation loops which leads to a slow dynamics of the flux [2].
© Springer Nature Switzerland AG 2019
Y. Farhaoui and L. Moussaid (Eds.): ICBDSDE 2018, SBD 53, pp. 20–26, 2019.
https://doi.org/10.1007/978-3-030-12048-1_4