Vector control of doubly-fed induction machine: robustness with respect to parameters variation

Electromechanical systems on the base of Doubly-Fed Induction Machine is an attractive solution for restricted speed range drives and energy generation applications. The concept of indirect stator flux orientation was introduced similarly to indirect rotor flux orientation. Line voltage amplitude, frequency and stator resistance have variations and cause torque errors. Robustness of the indirect flux oriented controller is studied in order to define the most critical variations

Prognostic System for Power Modules in Converter Systems Using Structure Function

This paper proposes an on-board methodology for monitoring the health of power converter modules in drive systems, using vector control heating and structure function to check for degradation. It puts forward a system that is used on-board to measure the cooling curve and derive the structure function during idle times for maintenance purposes. The structure function is good tool for tracking the magnitude and location of degradation in power modules. The ability to keep regular track of the actual degradation level of the modules enables the adoption of preventive maintenance, reducing or even eliminating altogether the appearance of failures during operation, significantly improving the availability of the power devices. The novelty in this work is the complete system that is used to achieve degradation monitoring; combining the heating technique and the measurement without additional power components except the measurement circuit which can be integrated into the gate drive board and the challenges encountered. Experimental results obtained from this show that it is possible to implement an on-board health monitoring system in converters which measures the degradation on power modules

Hybrid Speed Controller Design Based on Sliding Mode Controller Performance Study for Vector Controlled Induction Motor Drives

The discontinuous control of the sliding mode control (SMC) law causes chattering phenomenon in system trajectories (the oscillation around the desired value), which results in various unwanted effects such as current harmonics and torque ripples. Therefore, this study aims to investigate the performance of a sliding mode speed controller for a three-phase induction motor (IM) controlled by a rotor flux orientation technique to obtain optimum performance. The study results show that the experimental control gains found in the control law have a clear effect on limiting chattering and the system response speed. According to the study results, a hybrid controller is designed based on the fuzzy logic control (FLC) approach to optimally tune these gains. The designed hybrid controller is verified by experimental approximation of simulations using Matlab/Simulink. The simulation results show that the hybrid controller reduces the chattering phenomenon and improves the system’s dynamic performance

Torque Control Accuracy Using Different Techniques for Determination of Induction Motor Rotor Time Constant

Abstract – Induction motor (IM) drives represent a competitive solution for both industry and transports electrification. Most control solutions for induction motors currently perform the torque regulation by implementing field- oriented control (FOC) algorithms schemes defined in rotating dq coordinates. According to this scenario, the estimation of the d-axis position covers a key role to get good accuracy of the torque regulation. If considering the low-speed operation of the motor, the torque control performance is significantly affected by the accuracy in estimating the rotor time constant. According to the literature, this parameter can be computed using either the results of standard- (no-load and locked rotor tests) or flux-decay tests. However, these tests get unequal values of the rotor time constant, thus leading to a different torque control performance. Therefore, this paper aims at investigating the best value of the rotor time constant to optimize the accuracy of the FOC-based torque control. Experimental results obtained on a 4 poles IM, rated 10 kW at 6000 r/min, are presented

Performance study and analysis between vector control and direct power control for DFIG based wind energy system

This paper concentrates on analyzing the performance of the two most important techniques of independent active and reactive power control of the doubly-fed induction generator used in a variable speed wind power conversion system. In the first technique, the independent control of the active and reactive power is based on the vector control technique by the orientation of the stator voltage space vector using PI controllers; the decoupling components are deduced along with the d, q axes; and the PI controllers' parameters are calculated from the mathematical model of the doubly-fed induction generator. Hysteresis controllers are utilized to designing a direct power control technique. The performances of the studied control methods are tested and compared via simulation results

Performance Comparison of Different Speed Estimation Techniques in Sensorless Vector Controlled Induction Motor Drives

Field-oriented control and direct torque control are fast becoming necessities of modern industrial setups for induction motor drive control. Induction motors are considered as the beginning part to create any electrical drive system to be subsequently utilized for several industrial requirements. So now a day due to its high application the need to control the performance of the induction motor is gaining importance. In modern control system, IM is analyzed by different mathematical models mainly depending on its applications. Vector control method is suitably applied to induction machine in 3-phase symmetrical or in 2-phase unsymmetrical version. For vector control IM is realized as DC motor having its characteristics. This dissertation work is aimed to give a detailed idea about the speed control and variations in an induction motor through vector control technique thereby showing its advantage over the conventional scalar method of speed control. It also focusses on the speed estimation techniques for sensorless closed loop speed control of an IM relying on the direct field-oriented control technique. The study is completed through simulations with use of MATLAB/Simulink block sets allowing overall representation of the whole control system arrangement of the Induction motor. The performance of different sensorless schemes and comparison between them on several parameters like at low speed, high speed etc. is also provided emphasizing its advantages and disadvantages. The analysis has been carried out on the results obtained by simulations, where secondary effects introduced by the hardware implementations have not been considered. The simulations and the evaluations of different control techniques are executed using parameters of a 50 HP, 60 Hz induction motor which is fed by an inverter

Adaptive proportional-integral fuzzy logic controller of electric motor drive

This paper presents the indirect field vector control of induction motor (IM) which is controlled by an adaptive Proportional-Integral (PI) speed controller. The proposed solution can overcome the rotor resistance variation, which degrades the performance of speed control. To solve this drawback, an adaptive PI controller is designed with gains adaptation based on fuzzy logic in order to improve the performances of IM with respect to parameters variations, particularly the rotor resistance (Rr). The proposed control algorithm is validated by simulation tests. The obtained results show the robustness towards the load torque disturbances and rotor resistance variation of the adaptive Proportional-Integral fuzzy logic control with respect to classical PI control, and adaptive control based on rotor resistance observer