**Author details**

stator phase current with zoom is presented. The conventional DTC in **Figure 16** shows a chopped sinusoid waveform of current which indicates a high harmonic level, while SVM-DTC in **Figure 17(a)** shows a smoother sinusoid waveform. After that, the results exhibit the magnitude of stator flux evolution and circular trajectory. It is clear that the flux ripples of the conventional DTC have exceeded the hysteresis boundary. The magnitude and the trajectory illustrate that the flux takes a few steps before reaching the reference value (1.2 Wb) at the starting stage due to

The simulation in **Figure 17(b)** shows that the SVM-DTC-fuzzy has better performance than those obtained by both other DTC strategies (conventional and SVM-PI). There is an appreciable decrease in the start-up response time; we can notice that the speed regulation loop rejects the applied load disturbance very quickly which proves the performance of adaptive fuzzy-PI controller as well as a significant attenuation of the ripples of the torque and of the sinusoidal current

The main objective of this chapter is the improvement of the performance of an induction motor drive controlled by DTC. The objective of this improvement is to minimize the ripples of the couple and the flux of the IM on the one hand and the decrease of the switching frequency of the inverter on the other hand. In this context, a comparative analysis between different DTC strategies has been

presented. This chapter began by explaining the principle of the conventional DTC, SVM-DTC-PI, and SVM-DTC-fuzzy with adaptive Fuzzy-PI speed controller. The chapter presents later a discussion based on the simulation results presented in the same work. The synthesis of this simulation study reveals advantages of SVM-DTCfuzzy scheme compared to the two strategies: conventional DTC and SVM-DTC-PI. It has been observed by comparing the torque, speed, and stator flux characteristics that the method SVM-DTC-fuzzy is better. It is clear that the current is sinusoidal without any ripple in the steady state and torque ripples are reduced. In order to improve the SVM-DTC-fuzzy to have better performances, this method has been associated to the adaptive fuzzy-PI speed controller. This association makes the induction motor-based DTC perform more and more stable; there is an appreciable decrease in the start-up response time; we can notice that the speed regulation loop

**Item Symbol Data** IM mechanical power PW 1.5 kw Nominal speed *ω* 1420 rpm Nominal frequency f 50 Hz Pole pair number P 2 Stator resistance Rs 4.85 Ω Rotor resistance Rr 3.805 Ω Stator self-inductance Ls 274 mH

the zone's changing.

**11. Conclusion**

without any ripple in the steady state.

*Direct Torque Control Strategies of Electrical Machines*

rejects the applied load disturbance very quickly.

**A. IM motor parameters**

**34**

Cherifi Djamila\* and Miloud Yahia GACA Laboratory, University of Dr Moulay Tahar, Saida, Algeria

\*Address all correspondence to: d\_cherifi@yahoo.fr

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
