witched reluctance motors have received great attention for domestic and industrial applications over the past two decades. The disadvantage, however, is their inherent torque ripple due to their protruding motor stator and rotor poles. To overcome this drawback, useful control methods have been recently proposed, which may be kashida; TEXT-ALIGN: justify; LINE-HEIGHT: normal; TEXT-KASHIDA: 0%; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" torque, the total torque cannot be adjusted at all times within the hysteresis band cycle, which leads to increased torque ripple and reduced control accuracy. This is because the average torque in this case starts to reduce and to deviate from the reference. Four-level converters are, therefore, used both to enhance the current slope at the initial moment and to reduce the current along the conduction of the single phase due to the increased back emf. In fast excitation, DC link voltage (V DC ) and boost voltage (V B ) are supplied to phase winding. A number of problems arise when the speed increases. One such problem is the reduced excitation time which makes it difficult for the desired phase current to build up. Another is the larger torque ripple at higher motor speeds. However, the boost voltage of the 4-level topology breaks through voltage limitation, quickly building up the excitation current and rising voltage when current and torque decrease. The disadvantages of this converter include the low power factor and in most of convertors, controlling of boost capacity is important problem. To control of it the phase voltage should be increased when voltage increase is not necessity until boost capacity be discharged. In proposed converters, when the current falls due to increasing back emf voltage, V DC + V B voltage excites the phase to prevent torque reduction. Additionally, current pulsing is prevented by drawing current from the source at times when the voltage source is capable of providing the required current, a process which leads to reduced current amplitude and improved power factor Keywords: Direct Instantaneous Torque Control (DITC) , Hysteresis control, power factor ,Switched Reluctance Motor.
