International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-1, October 2012 53 Abstract— Three phase pluse width modelation voltage soruce inverter are widly used in many industrial application such as the drive system. The performance of the drive systems depend up on the motor control and method of control in power converter. From the most important methods to control the power converter are current and voltage controls. The current control is preferable. This is because it is simple. The quality control of this method depends upon the quality of the waveform is generated by current controlled of converter. This paper aims to improve the performance of Ac drives through the improvement the different methods of the current controlled. Here the classical hysteresis controller, ramp type controller and delta modulator controller are discussed and improvement by general design of PI current controller for each phase. The improvement can be seen through the torque ripple and total harmonic distortion. The proposed model is compared to classical model to show the effectiveness of the proposed model. This work is simulated through matlab simulink. Index Terms— hysteresis controller, delta modulator controller, ramp type controller, matlab simulink. I. INTRODUCTION Inverter-fed AC-machines are widely used in industrial applications. In particular, to achieve fast torque responses and high-performance operation, Permanent magnet synchronous motors (PMSM) are often used together with high performance current controls. These motors (PMSM) become popular in various applications due to have some advantage as, high power density and efficiency, high power factor, high torque to inertia ratio, high reliability, low rotor inertia, efficient heat dissipation structure, and reduced motor size. So it has received widespread appeal in industrial applications such as aero space, nuclear power plant, robotics, adjustable speed drives and electric vehicles. In these motors (PMSM) the permanent magnet material is placed on the rotor by many methods. Among these methods, surface mounted magnets, inset magnets and buried magnets [1].The method of motor control is very important in the drive system. This is because the operation of the PMSM under some methods of control is suffered from complicated coupling and nonlinear dynamic performance. This problem can be solved by field oriented control [2-3]. Field oriented control technology makes high-performance PMSM be widely applied. However, the control performance of PMSM is still influenced by the uncertainties of the plant, which include plant parameter variations and external load disturbances. Internal model control (IMC) can offer many good properties, Manuscript received on October 2012 Hamdy Mohamed Soliman, General Manger in cairo Merto Gereater, Hellwan, Egypt. S. M.EL. Hakim, Department of Electrical Power and Machines Engineering, Cairo University/ Engineering College, Giza, Egypt. such as easy design, good ability of disturbance rejection, and so on. Due to the advantages motioned above, IMC has been used widely in the field of AC motor drive systems [4-5].To achieve the field oriented control of PMSM, knowledge of the rotor position is required. Usually the rotor position is measured by a shaft encoder, resolver, or Hall sensors [6-7]. PMSM with field oriented control emulates the separately excited DC motor. In this method of control, the stator current can be decupled into flux and torque current components. They can be controlled separately. In four quadrant with keeping magnetic circuit linear, under perfect field oriented control, with constant flux operation, applying the principles operation of the field oriented control, the linear relation can be described the motor torque. However, the control performance of PMSM drive is still influenced by uncertainties, which usually are composed of unpredictable plant parameter variations, external load disturbances and nonlinear dynamics of the plant and harmonics in both motor and inverter. These problems shaped difficult in getting robust control. They lead to problems in torque and oscillation in the speed as the secondary problem comes from torque problem. There are many methods of control tried to get rid these problem by design robust current control of the drive system. The dynamic performance of voltage source inverter (VSI) fed PMSM drive system largely depends on the applied control strategy. The quality control of these methods depend upon the quality of the waveform is generated by method control of converter. Good power waveform depends upon the switching frequency of PWM, modulation index and the shape of current or voltage wave forms. The control method in inverter is voltage control or current control. The current control is preferable due to simple. PWM current-controlled voltage source inverters are widely used in high performance ac drives for quick response and accurate control. It has substantial advantage in eliminating stator dynamics in high performance ac drive systems under field oriented control. There many methods of current control such as: linear and non-linear current controllers. Linear controller includes PI controller, state feed back controller and predictive current controller. Nonlinear controller includes bang-bang controllers (Hysteresis control, ramp type control and delta modulator) and predictive controllers with online-optimization [8]. Here PWM hysteresis current control, ramp type control and delta modulator are discussed. In these methods of current control, the load currents are measured and compared with the reference currents. The error is used as the input to the PWM which is used to drive the switching frequency of inverter. In this paper adaptive hysteresis current controller, ramp type controller and delta modulator controller are proposed. This can be done by design PI current controller in each phase of the inner loop of current controlled inverter. It is approximately vanish the torque ripple and improvement the total harmonic distortion Improvement the Current Control Methods for Three Phase Voltage Source Inverter to Drive the Permanent Magnet Synchronous Motor Hamdy Mohamed Soliman, S. M. EL. Hakim