Power Electronics
Zahra Emami; Abolfazl Halvaei Niasar
Abstract
Background and Objectives: Multiphase electric motors are useful for industrial and military applications that need high power, smooth torque and the ability sharing power and torque in comparison to conventional three-phase electric motors. Also, these motors a more suitable substitute than three-phase ...
Read More
Background and Objectives: Multiphase electric motors are useful for industrial and military applications that need high power, smooth torque and the ability sharing power and torque in comparison to conventional three-phase electric motors. Also, these motors a more suitable substitute than three-phase motors because of their ability to manage fault condition, guaranteeing the postfault operation of the drive. One type of Multiphase electric machines is Permanent Magnet Brushless Motors (PMBLM) that due to the inevitable limitations in their construction, back-EMF voltages are neither sinusoidal nor trapezoidal. Using traditional control strategies of and Brushless DC Motors (BLDCM) and Permanent Magnet Synchronous Motors (PMSM) results high electromagnetic torque ripple, vibrations and noises that are undesirable for medium voltage applications. Methods: This paper suggests a new finite control set model predictive control (FCS-MPC) method for two diode-clamped three-level (DC3L) inverters fed non-sinusoidal dual three phase PMBLM (DTP-PMBLM) with the capability to manage pre-fault conditions for reduction torque ripple and withstand postfault situations. The suggested MPC method removes requirement of weighting factor in the cost function for neutral point voltages in both DC3L inverters with a simple scheme balancing of capacitive voltages. Also, the fault tolerant control (FTC) schemes open phase fault and open switch fault are considered.Results: To study the effectiveness of the suggested MPC method, simulation results non-sinusoidal DTP-PMBLM drive are investigated and compared to with multiband hysteresis current (MHC) controller. Simulations have been carried out using MATLAB/Simulink with specifications 4125-V/2.7MW/350-RPM. Conclusion: Simulation results validate that the suggested MPC method has great dynamic responses such as lower torque ripple than the MHC controller. The FTC schemes are implemented without complexity changing the mathematical model and control framework.
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 ...
Read More
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 ...
Read More
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, ...
Read More
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.
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 ...
Read More
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.
