Power Electronics
M. Nabizadeh; P. Hamedani; B. Mirzaeian Dehkordi
Abstract
Background and Objectives: Due to the disadvantages of the traditional AC-DC-AC converters, especially in electric drive applications, Matrix Converters (MCs) have been widely researched. MCs are well-known structures that remove the DC-Link capacitor and provide bidirectional power flow, while also ...
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Background and Objectives: Due to the disadvantages of the traditional AC-DC-AC converters, especially in electric drive applications, Matrix Converters (MCs) have been widely researched. MCs are well-known structures that remove the DC-Link capacitor and provide bidirectional power flow, while also giving the ability to control reactive power flow, which the AC-DC-AC converter lacks. Methods: In this work, Model Predictive Current Control (MPCC) is utilized in conjunction with the MC to provide more versatility and controllability than traditional control methods. The work endeavors to investigate the current control of the MC utilizing the finite control set Model Predictive Control (MPC) approach. Results: Current tracking performance, reactive power control, and switching frequency minimization have been included in the objective function of the controller. Moreover, the results have been compared to the traditional AC-DC-AC converters under similar circumstances. The MC can reduce the switching frequency by 40% compared to the AC-DC-AC converter while maintaining the same current THD value. Additionally, it achieves a 58% reduction in current THD compared to the AC-DC-AC converter at the same average switching frequency. However, in the MC, the mitigation of reactive power and the reduction in switching frequency have opposing effects on the current tracking performance.Conclusion: This work proposes an MPCC method for the MC with an RL load, effectively controlling load current and reactive power. The reduction of switching commutations was also evaluated using different weighting factors in the prediction strategy for both the MC and AC-DC-AC converters. Simulation results demonstrate that the MC outperforms the AC-DC-AC converter in dynamic response and reactive power control.
Power Electronics
P. Hamedani
Abstract
Background and Objectives: To overcome the disadvantages of the traditional two-level inverters, especially in electric drive applications, multi-level inverters (MLIs) are the widely accepted solution. Diode-Clamped Inverters (DCIs) are a well-known structure of multi-level inverters. In DCIs, the voltage ...
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Background and Objectives: To overcome the disadvantages of the traditional two-level inverters, especially in electric drive applications, multi-level inverters (MLIs) are the widely accepted solution. Diode-Clamped Inverters (DCIs) are a well-known structure of multi-level inverters. In DCIs, the voltage balance of the DC-link capacitors and the Common Mode (CM) voltage reduction are two important criteria that should be considered. Methods: This paper concentrates on the current control of 3-phase 4-level DCI with finite control set model predictive control (MPC) strategy. Current tracking performance, DC-link capacitor voltage balance, switching frequency minimization, and CM voltage control have been considered in the objective function of the MPC. Moreover, the multistep prediction method has been applied to improve the performance of the DCI. Results: The effectiveness of the proposed multistep prediction control for the 4-level DCI has been evaluated with different horizon lengths. Moreover, the effect of several values of weighting factors has been studied on the system behavior. Conclusion: Results validate the accuracy of current tracking and voltage balancing in the suggested multistep MPC for the 4-level DCI. In addition, CM voltage control and switching frequency reduction can be included in the predictive control. Decreasing the CM voltage and switching frequency will oppositely affect the dynamic behavior and voltage balancing of the DCI. Therefore, selection of weighting factors depends on the system needs and requirements.
Power Electronics
P. Hamedani; M. Changizian
Abstract
Background and Objectives: Model predictive control (MPC) is a practical and attractive control methodology for the control of power electronic converters and electrical motor drives. MPC has a simple structure and enables the simultaneous consideration of different objectives and constraints. However, ...
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Background and Objectives: Model predictive control (MPC) is a practical and attractive control methodology for the control of power electronic converters and electrical motor drives. MPC has a simple structure and enables the simultaneous consideration of different objectives and constraints. However, when applying MPC for multilevel inverters (MLIs), especially at higher voltage levels, the number of switching states dramatically increases. This issue becomes more severe when MLIs are used to supply electrical motor drives.Methods: This paper proposes three different MPC strategies that reduce the number of iterations and computation burden in a 3-phase 4-level flying capacitor inverter (FCI). Traditional MPC with a reduced number of switching conditions, split MPC, and hybrid MPC-PWM control are investigated in this work.Results: In all methods, the capacitor voltages of the FCI are balanced during different operational conditions. The number of iterations is reduced from 512 in traditional MPC to at least 192 in the split MPC. Moreover, the split MPC strategy eliminates the usage and optimization of weighting factors for capacitors voltage balance. However, in the hybrid MPC-PWM control method in comparison to other methods, the voltage balancing time is much lower, the phase current tracks the reference more accurately, the transient time is lower, and the efficiency is higher. In addition, the capacitors voltage ripple is negligible in the hybrid MPC-PWM control method.Conclusion: Simulation results manifest the effectiveness of the suggested hybrid MPC-PWM methodology. Results manifest that the hybrid MPC-PWM control offers perfect dynamic characteristics and succeeds in maintaining the voltage balance during different operational conditions.
Power Electronics
P. Hamedani; S. S. Fazel; M. Shahbazi
Abstract
Background and Objectives: Modeling and simulation of electric railway networks is an important issue due to their non-linear and variant nature. This problem becomes more serious with the enormous growth in public transportation tracks and the number of moving trains. Therefore, the main aim of this ...
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Background and Objectives: Modeling and simulation of electric railway networks is an important issue due to their non-linear and variant nature. This problem becomes more serious with the enormous growth in public transportation tracks and the number of moving trains. Therefore, the main aim of this paper is to present a simple and applicable simulation method for DC electric railway systems.Methods: A train movement simulator in a DC electric railway line is developed using Matlab software. A case study based on the practical parameters of Isfahan Metro Line 1 is performed. The simulator includes the train mechanical movement model and power supply system model. Regenerative braking and driving control modes with coasting control are applied in the simulation.Results: The simulation results of the power network are presented for a single train traveling in both up and down directions. Results manifest the correctness and simplicity of the suggested method which facilitates the investigation of the DC electric railway networks.Conclusion: According to the results, the train current is consistent with the electric power demand of the train. But the pantograph voltage has an opposite relationship with its electric power demand. In braking times, the excess power of the train is injected into the electrical network, and thus, overvoltage and undervoltage occur in the overhead contact line and the substation busbar. Therefore, at the maximum braking power of the train, the pantograph voltage reaches its maximum. The highest amount of fluctuation is related to the substation that is closest to the train. As the train moves away from the traction substations, the voltage fluctuations decrease and vice versa.
Linear Induction Motors
P. Hamedani; S. Sadr
Abstract
Background and Objectives: Linear Induction Motors (LIMs) are favorite machines utilized in various industrial applications. But, due to the end effect phenomena, control of a LIM drive is more complicated than rotational machine drives. Therefore, selecting the proper control strategy for a LIM drive ...
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Background and Objectives: Linear Induction Motors (LIMs) are favorite machines utilized in various industrial applications. But, due to the end effect phenomena, control of a LIM drive is more complicated than rotational machine drives. Therefore, selecting the proper control strategy for a LIM drive has been a significant challenge for the researchers.Methods: This paper concentrates on a new Model Predictive Control (MPC) of LIM drives which considers the end effect.Accordingly, the discrete-time model of the LIM with end effect is extracted, and the required flowchart used for the MPC of LIM drive has been presented in this paper.Results: To study the effectiveness of the suggested strategy, simulation results of a LIM drive with MPC are presented and compared to the traditional Indirect Field Oriented Control (IFOC) of LIM drive. Simulations have been carried out using Matlab. The end effect has been considered in the LIM model and control strategies.Conclusion: Simulation results validate that the suggested MPC of LIM drive yields excellent dynamic characteristics such as fast speed response with no overshoot. Moreover, in comparison to the traditional IFOC method, the suggested MPC strategy offers lower current ripple and lower electromagnetic force ripple, and therefore, it is suitable for industrial drive applications.
Power Electronics
P. Hamedani; S. Sadr; A. Shoulaei
Abstract
Background and Objectives: The principal aim of this paper is to show an independent vector control of two five-phase Linear Induction Motors (LIMs) that are supplied from a single VSI. Methods: The LIMs are running at the same speed but with different load conditions. This concept can be especially ...
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Background and Objectives: The principal aim of this paper is to show an independent vector control of two five-phase Linear Induction Motors (LIMs) that are supplied from a single VSI. Methods: The LIMs are running at the same speed but with different load conditions. This concept can be especially beneficial in long trains with distributed power. To achieve excellent control characteristics and to reduce the undesirable tension forces between the train mechanical couplers, Fuzzy Logic Controllers (FLCs) have been utilized.Results: As a result, the fault occurrence of the train control systems decreases, and the system reliability increases. The results prove the electrical independence in control of a five-phase two-LIM drive supplied with a single VSI. Furthermore, in the presence of the train mechanical couplers and connections, the application of FLC offers excellent control characteristics and reduces the undesirable tension forces. Furthermore, to obtain a more worthwhile validation of the theoretical results, an experimental set up has been constructed and results have also been presented.Conclusion: According to the results, the undesirable tension forces imposed on train couplers are reduced. Consequently, it leads to higher system efficiency, lower deterioration of the train couplers and connections, greater system reliability, and higher passenger safety and comfort.
Power Electronics
P. Hamedani; A. Shoulaei
Abstract
Background and Objectives: Despite superior privileges that multiphase motors offer in comparison with their three-phase counterparts, in the field of multiphase linear induction motors (LIMs) few studies have been reported until now. To combine the advantages of both multiphase motors and linear induction ...
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Background and Objectives: Despite superior privileges that multiphase motors offer in comparison with their three-phase counterparts, in the field of multiphase linear induction motors (LIMs) few studies have been reported until now. To combine the advantages of both multiphase motors and linear induction motors, this paper concentrates on multiphase LIM drives considering the end effects.Methods: The main contributions of this paper can be divided into two major categories. First, a comparative study has been conducted about the dynamic performance of Fuzzy Logic Controller (FLC) and Genetic-PI controller for a seven-phase LIM drive; and second, because of the superior performance of the FLC method revealed from the results, the harmonic pollution of the FLC based LIM drive has been studied in the case of supplying through a five-level Cascaded H-bridge (CHB) VSI and then compared with the traditional two-level VSI fed one.Results: The five-level CHB-VSI has utilized a multiband hysteresis modulation scheme and the two-level VSI has used the traditional three-level hysteresis modulation strategy. Note that for harmonic distortion assessment both harmonic and interharmonic components are considered in THD calculations.Conclusion: The results validate the effectiveness of the proposed FLC for seven-phase LIM drive supplied with five-level CHB-VSI and guarantee for perfect control characteristics, lower maximum starting current, and significant harmonic and interharmonic reduction.
