H. Dahmardeh; M. Ghanbari; S.M. Rakhtala
Abstract
In this paper, a novel combined Direct Torque Control (DTC) method and Stator-Flux Oriented Control (SFOC) system to increase general performances of Three-Phase Induction Motor (TPIM) drives is proposed. The introduced control scheme includes merits of DTC for instance simple structure, less dependent ...
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In this paper, a novel combined Direct Torque Control (DTC) method and Stator-Flux Oriented Control (SFOC) system to increase general performances of Three-Phase Induction Motor (TPIM) drives is proposed. The introduced control scheme includes merits of DTC for instance simple structure, less dependent on PI controller coefficients, fast dynamics, and merits of SFOC such as high precision and constant switching frequency. Specifically, the proposed control scheme includes a table-based variable structure developed on DTC strategy and a PI controller in connection with a Pulse Width Modulation (PWM) algorithm based on SFOC strategy. To confirm the usefulness of the introduced controller, simulation studies are accomplished for a 2.5kW TPIM in different situations. Results under the presented control system approve the good performances of this technique in comparison with classic DTC and classic SFOC. Investigation in TPIM performances under the introduced control system indicates relatively quick dynamic responses with low torque and stator flux ripples.
A. Gholipour; M. Ghanbari; E. Alibeiki; M. Jannati
Abstract
Current sensors are required in Field-Oriented Control (FOC) strategies of Three-Phase Induction Motor (TPIM) drives. Nevertheless, the current sensors are subject to different electrical/mechanical faults which reduce the safety and dependability of the drive system. Single phase current sensor Fault-Tolerant ...
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Current sensors are required in Field-Oriented Control (FOC) strategies of Three-Phase Induction Motor (TPIM) drives. Nevertheless, the current sensors are subject to different electrical/mechanical faults which reduce the safety and dependability of the drive system. Single phase current sensor Fault-Tolerant Control (FTC) for sensorless TPIM drives using flux observer and Extended Kalman Filter (EKF) is proposed in this research. In the suggested FTC scheme, current sensor fault detection is based on axes transformation, a logic circuit is served as the fault isolation and reconstruction of faulted currents are achieved through flux observer and EKF. The presented FTC system is capable of detecting and localizing the current sensor fault and switching the drive system to tolerant FOC mode without the rotor speed measurement. The effectiveness of the suggested FTC system is confirmed by experiments on a 0.75kW TPIM drive platform.
A.H. Mashhadzadeh; M. Ghanbari; A. Koochaki; M.G. Ahangari
Abstract
Improving the insulating and thermal properties of transformer oil is one of the factors in the use of nanoparticles (NPs) in oil. However, the use of NPs may only have a positive effect on some properties of the oil or even have a negative effect on the other properties of the oil. For this reason, ...
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Improving the insulating and thermal properties of transformer oil is one of the factors in the use of nanoparticles (NPs) in oil. However, the use of NPs may only have a positive effect on some properties of the oil or even have a negative effect on the other properties of the oil. For this reason, hybrids nanofluid(HNF) were used to improve the properties of the transformer oil. By performing the Breakdown Voltage (BDV) test on different weight percentages (wt%) of TiO2 and CNT, it was proved that the best wt% for TiO2 is 0.0075 and for CNT is 0.001 to maximize the BDV. In this case, the HNF was able to improve the BDV and heat transfer by 9% and 8%, respectively. Another surprise that the HNF has been able to reduce the amount of C2H4 and C2H6 dissolved in oil by more than 70%. This reduction in the number of gases has another very desirable result and has reduced the PD by 63%. HNF proved that by using the right combination of different nanomaterials in transformer oil, more properties of the transformer oil can be improved.
M. Nikpayam; M. Ghanbari; A. Esmaeli; M. Jannati
Abstract
Reliability for electric motor drive systems is very vital in some industries. Selecting an appropriate control strategy for driving an electric motor during fault conditions is one of the most important issues mainly for safety-critical applications. Recently, vector control (VC) strategies have been ...
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Reliability for electric motor drive systems is very vital in some industries. Selecting an appropriate control strategy for driving an electric motor during fault conditions is one of the most important issues mainly for safety-critical applications. Recently, vector control (VC) strategies have been extensively developed for star-connected three-phase induction motor drives during single-phase cut-off fault (COF) based on two different transformation matrices (TMs). Despite the effectiveness of these methods during the fault, these control systems are very complex due to their extensive on-line computation. This paper presents two simple methods based on indirect VC (IVC) and direct VC (DVC) methods for controlling a star-connected three-phase induction motor during the fault condition. The fault in this paper is limited to single-phase COF which can occur in motor stator coils. In this paper, it is shown that using a suitable TM and some changes in the control parameters, it is possible to control the faulted drive system. Performance of the proposed control methods is verified using MATLAB software and DSP/TMS320F28335 controller board for a 0.75kW star-connected three-phase induction motor drive system. The achieved results show the good performance of the introduced control systems in different operating conditions. In addition, the results demonstrate the performance of the proposed VC strategies and that of the previous works are almost the same. However, the proposed VC methods in this paper need less modification in the structure of the standard VC strategy than the previous works.
M. Shabandokht-Zarami; M. Ghanbari; E. Alibeiki; M. Jannati
Abstract
The Vector Control (VC) of Y-Connected Induction Motor (YCIM) drives is entirely demanding task. Furthermore, YCIM under an Open-Circuit Fault in the Stator Coils (OCFSC) leads to deterioration of the VC. Consequently, the VC of YCIMs under an OCFSC requires a suitable design. This research focuses on ...
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The Vector Control (VC) of Y-Connected Induction Motor (YCIM) drives is entirely demanding task. Furthermore, YCIM under an Open-Circuit Fault in the Stator Coils (OCFSC) leads to deterioration of the VC. Consequently, the VC of YCIMs under an OCFSC requires a suitable design. This research focuses on an accurate and modified Field-Oriented Control (FOC) strategy for 3-phase YCIM drives under an OCFSC. Most of the recent papers studying VC of YCIMs under an OCFSC ignore the leakage inductance in the VC equations. This paper presents an alternative VC technique, considering the leakage inductance in the VC equations of YCIMs under an OCFSC. In the presented VC system, two asymmetrical Rotating Transformations (RTs) for the stator current and voltage quantities are proposed and employed. In the proposed scheme, the genetic algorithm is used to regulate the parameters of the Proportional-Integral (PI) controllers. The developed VC system provides an accurate control against an OCFSC and can be employed for different industries that need Fault-Tolerant Control (FTC) systems. The effectiveness of the proposed approach is validated through experimentation in the laboratory. The proposed control scheme gives good responses during both steady state and transient sate. In addition, the proposed VC system gives better performances during the post-fault operation compared to previous works in terms of speed and torque ripples.
Insulation & High Voltage
M. Hasanpour; M. Ghanbari; V. Parvin-Darabad
Abstract
Mitigating switching overvoltages (SOVs) and conducting well-suited insulation coordination for handling stresses are very important in UHV transmission Lines. The best strategy in the absence of arresters is controlled switching (CS). Although elaborate works on electromagnetic transients are considered ...
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Mitigating switching overvoltages (SOVs) and conducting well-suited insulation coordination for handling stresses are very important in UHV transmission Lines. The best strategy in the absence of arresters is controlled switching (CS). Although elaborate works on electromagnetic transients are considered in the process of designing transmission systems, such works are not prevalent in day-to-day operations. The power utility and/or operator have to carefully monitor the peak values of SOVs so this values not to exceed the safe limits. In this paper, we present a novel CS approach in dealing with EMTP/ATP environment, where trapped charge (TC) is intended to train a radial basis function network (RBFN) meta-model that is implemented to calculate SOVs. A new weighted maximum overvoltage factor proposed to find locations of critical failure risk due to SOVs occurred along transmission lines. Power utilities or design engineers can benefit from the presented meta-model in designing a well-suited insulation level without spending time for taking into account the feasible risk value. Besides, the operators can energize the lines sequentially upon their choice; i.e., a safe and proper energization.
