چكيده لاتين
Today, optimizing and saving energy consumption, meaning the use of electrical equipment, with minimum energy consumption and maximum efficiency, has been considered from two economic and environmental aspect. Electric motors, as one of the major consumers of electric power, consume above 60% of the produced electric energy. As a result, global research on the optimization of energy consumption by motordrives is being carried out rapidly. Electric motors, used in industries and household applications, are often DC or induction. DC motors, despite their desirable properties such as ease of control, due to having a costly maintenance, have given their place to other motors. The use of variable speed control methods in induction motors, despite the increase in system efficiency, in many applications, they lack the benefit and proper performance quality. Over the past two decades, with the decrease in the price of permanentmagnet materials, advantages such as high efficiency, high power density, linear speed torque characteristic, simple control and superior speed performance have caused BLDC motors to be used in many industrial applications such as machinery, aerospace, medical and industrial automation industries. The most important problem of these motors is the output torque ripple, as well as the ineffectiveness of the motor control methods due to the uncertainty in the system model or input disturbances, which can cause the mechanical vibration and noise. As the motor speed increases, this torque ripple also increases; As a result, the use of this motor, in precise applications such as robotics, is restricted.
In order to reduce the ripple torque of BLDC motor, in this thesis, the equations of input active and reactive power to the airgap are first stated, and then a robust method based on the supertwisting sliding mode control method is presented to directly control the power of BLDC motor. The sliding surfaces in the proposed method are defined based on the active and reactive power errors, and whenever these surfaces converge to zero, the power errors will also converge to zero, and as a result, the torque ripple will decrease. The use of supertwisting sliding mode control method, in addition to its robust performance, will eliminate chattering phenomenon, which can cause high frequency vibrations. Also, regarding increasing the motor speed above the rated speed, in this thesis, a closedloop linear method is proposed to control the active and reactive powers of the motor. The proposed method includes two active and reactive power control loops, the reactive power loop is activated only in the field weakening region. Each of the proposed methods is first compared with other methods by simulation results in the Simulink environment, and then the practical results of implementing these methods on a laboratory prototype are presented in this thesis. The obtained results show that each of the proposed methods perform better in terms of response speed and torque ripple reduction compared to other methods.
