Effect of the Parameters Variation for Induction Motor on its Performance Characteristics with Field Oriented Control Compared to Scalar Control

Induction motor is used in many industrial applications due to have low cost, low maintenance, high efficiency, rugged structure and long operation life at medium and high loads. The control methods for electrical machine are different from method to another method. In these methods of control some machine parameters must be very well to get high dynamic performance. These parameters are not constant and differ from operating point to another operating point i.e. these parameters are affected by temperature, saturation, frequency and skin effect. So this paper is importance to the effect of the all parameters variation of induction motor with field oriented control (FOC) and with scalar control (SC) at constant flux region and at field weakening region at starting point and at full load point. In the scalar control, the portion of voltage and frequency are kept constant as a magnitude to keep the airgap motor flux constant which means that constant motor torque [1-5]. This motor torque is at rated this is because the motor flux is constant. In the above rated speed (field weakening region), the frequency varies and the applied motor voltage is kept constant so the motor torque is inversely proportional to speed due decrease of the flux. In the closed loop scalar control some parameters are needed to avoid the saturation and getting the good slip speed. The saturation may be occurred due to the motor may be under excited or over excited depending upon the region which working in it. Also FOC saves high dynamic performance for AC drives this because the AC machine with FOC emulate the DC motor i.e. the stator and rotor flux are perpendicular. In this control type, the portion of voltage and flux is constant in the constant flux region as SC but the machine parameters such as flux, current and voltage are controlled as the vector in the space [6-9]. Also above the base speed, the motor voltage is kept constant and frequency increase as SC control and the machine parameters (flux, current and voltage) are controlled as the vector in the space. In spite of the FOC is good control and saves high dynamic performance but the high performance is lost when occurred mismatching between the motor parameters and the estimating motor parameters that are used in the control. So this paper is discussed the effect of parameters variation on the performance characteristics of induction motor with FOC compared to SC at starting and at full load. This paper concluded that, I introduction, II mathematical model, III scalar control, IV field oriented control and V simulation results VI conclusion.