International Research Journal of Advanced Engineering and Science ISSN (Online): 2455-9024 232 Jagdish G. Chaudhari and Dr. Sanjay B. Bodkhe, ―Implementation of direct torque control induction motor drive using MATLAB,‖ International Research Journal of Advanced Engineering and Science, Volume 2, Issue 2, pp. 232-236, 2017. Implementation of Direct Torque Control Induction Motor Drive using MATLAB Jagdish G. Chaudhari 1 , Dr. Sanjay B. Bodkhe 2 1 Research Scholar, Department of Electrical Engineering, G.H. Raisoni College of Engg. Nagpur, Maharashtra, India-440016 2 Professor, Department of Electrical Engineering, Ramdeobaba College of Engg. & Management, Nagpur, Maharashtra, India Abstract— This paper describes how space vector pulse width modulation can be realized in direct control method by maintaining the hysteresis band of the stator flux path in a proper way. This band is varied in predefined way which depends on the angle of the reference voltage vector. Keywords— Direct torque control, space vector pulse width modulation, hysteresis band controller. I. INTRODUCTION With the continuous improvement of technology in power electronics and micro-electronics, variable voltage and variable frequency ac motor drives have come to increased use in various industrial applications. These new approaches need a simple method of control for ac motors. Control of ac motors become very popular because it is possible to obtain the characteristics of dc motors by improving control techniques. It is well-known that the control method of an ac motor is comparatively more difficult to realize because of involvement of various controllable parameters like voltage, current, frequency, torque, flux and so on. Though it is possible to achieve almost the same characteristics of dc motor using induction motor, it is very complicated to realize because of need for on line co-ordinate transformation and continuous need of either speed or position signal. Particularly, field oriented control, which guarantees high dynamic and static performance like dc motor drives, has been very popular and has constantly being developed and improved. But the innovative idea of co-ordinate transformation and the analogy with dc motor control. This substituted non-linear co-ordinate transformation in field oriented control by self control of stator flux and torque. In contrast to the control of the direct and quadrature component stator currents to maintain desired flux and torque respectively, this scheme directly controls those two parameters in stationery frame, while currents and voltages are regulated indirectly. As the concept of instantaneous space vector becomes very popular, ac drives controllers will use this tool as a PWM technique. Moreover, since quick accelerating and decelerating rotation of stator flux vector is achieved, rapid torque response can be obtained. To achieve this, both torque and flux controllers employ hysteresis band with the objective to maintain both the machine variables within their respective tolerance bands. Due to direct application of active voltage vector by the modulator, sometimes stator voltage vector moves very fast tangentially along the circular path of stator flux vector within the flux hysteresis band leading to non-sinusoidal voltage across the stator terminal. This introduces some harmonic voltages leading to increased loss of the machine. So, the concentration should be given on the generation of pulse width modulation waveform such that the inverter output voltage magnitude can be maintained close to sinusoidal wave shape averaged over switching sub-cycle. II. SPACE VECTOR CONCEPT As we know a single vector known as space vector can be represent a set of three phase vectors. The transformation three-phases to stationary d-q frame are given by following equation.                             Vc Vb Va Vq Vd 2 3 2 3 0 2 1 2 1 1 3 2 (1) With further simplification, we get      Vc Vb j Vc Vb Va V      2 1 ) ( 5 . 0 3 2 (2) This constant 3 2 comes into picture in order to maintain power and impedance matrix invariance between transformation. Fig. 1.1. Transformation for 3-ph to stationary d-q axis. Consider a 3-phase inverter shown in figure 1.2. It is well- known that the three phase inverter can be produce 8 output states. For all possible switching states, corresponding phase voltage & the voltage space vector are shown in the following table (1). Switching states 100 means, upper switching phase ‗a‘ is closed and upper switch in phase ‗b‘& ‗c‘ are open. Thus 8 output states of inverter represent 8 space vectors, two vectors i.e.V7[000] &V8[111] are null & remaining 6 are of equal magnitude & arranged 60 0 apart in space diagram as shown in fig. 1.3. Switching stages are shown in fig. 1.5. By considering the six pulse VSI shown in figure, there are six nonzero active voltage switching space vectors and two