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Öğe Asymmetrical Multi-Step Direct Model Predictive Control of Nine-Switch Inverter for Dual-Output Mode Operation(Ieee-Inst Electrical Electronics Engineers Inc, 2019) Gulbudak, Ozan; Gokdag, MustafaNine-Switch Inverter (NSI) is composed of two conventional inverters with three common switches. Two sets of three phase ac loads can be connected to the outputs of NSI and independently controlled without any undesirable interaction. In conventional multi-step Model Predictive Control (MPC) of a nine-switch inverter, the prediction steps of both load stages must be equal. Unfortunately, this results in losing the freedom of selecting independent prediction horizon for individual loads. To overcome this problem, a novel asymmetrical multi-step direct model predictive control method is presented in this paper. The proposed method finds two independent optimum solutions for each load to match with their utilization profile. It is assumed that two individual loads are controlled by two separate virtual inverters, and two separate model predictive control problems with their own prediction steps are solved to identify optimum control actions. The control calculations are performed in a Cyclone IV Field Programmable Gate Array (FPGA) by using a pipelined architecture. The system stability is analyzed using Lyapunov stability method. To highlight the effectiveness of introduced strategy, mathematical proof for controlling two separate loads with an asymmetrical prediction step is validated in experimentally.Öğe Cascaded IMC & PI Digital Controller Comparison for Boost Converter with Non-Ideal Switch Modelled State-Space Averaging Method(Ieee, 2023) Hukumen, Burhan; Gokdag, Mustafa; Gulbudak, OzanIn this study, two different closed-loop digital controllers have been implemented for a CCM boost converter and advantages of the controllers have been compared. The first one was designed as cascaded PI controller and second one designed as cascaded internal model controller (IMC). In the modelling process of the boost converter, the sate-space averaging technique has been used considering equivalent series resistances (ESR) and non-ideal switch models which impact the response of the converter system. In order to make the designed controllers appropriate for digital control technique, they have been discretized by bilinear transformation method and Matlab/Simulink simulations have been realized as if digital controllers have been implemented through a digital signal processor (DSP). The response of the controllers against load change, reference changes and input voltage change has been observed and compared.Öğe Data-Driven TD3 Control of IM Considering Magnetic Saturation and Temperature Effect(Ieee, 2024) Korpe, Ugur Ufuk; Gokdag, Mustafa; Gulbudak, OzanInduction machines (IM) are still widely used in the industry due to their advantages, such as low maintenance requirements and improved robustness. The field-oriented control (FOC), direct torque control (DTC), and model predictive control (MPC) techniques are used to control IM in high-performance control applications. The common disadvantage of these control techniques is that the control performances are negatively affected by changes in machine parameters, and machine parameters vary non-linearly depending on the magnetic saturation and temperature. To solve this negative affect, the control technique can be optimized by using a parameter estimation methods. Another solution to eliminate these negative effects is to design a reinforcement learning (RL)-based controller that regulates the control variables without the knowledge of machine parameters. In this study, IM speed control is performed using a twin-delayed deep deterministic policy gradient (TD3) agent. The dynamic and steady-state performance of the designed controller are compared with the traditional control techniques. Extensive simulation results have shown that the dynamic and steady-state performance of the designed controller is better than other control techniques.Öğe Dual-Hysteresis Band Control of Nine-Switch Inverter to Control Two Induction Motors(Ieee-Inst Electrical Electronics Engineers Inc, 2022) Gulbudak, Ozan; Gokdag, MustafaThis paper presents a dual-hysteresis band control method for multi-drive systems based on a nine-switch inverter. The drive system contains two independent three-phase induction motors fed by a nine-switch inverter. Independent control of torque, speed, and stator current of two load stages is achieved. The proposed strategy offers a reliable control operation of both induction machines under individual load profiles. Instead of using independent sets of three-phase voltage source converters, the nine-switch inverter is used to drive separate machines. Thus, the volume and size of the power stage are noticeably reduced due to the use of fewer semiconductors. The theoretical concept and design steps of the proposed method are presented. The performance of the closed-loop independent motor control scheme is experimentally validated using a 3.2 kW lab-scaled nine-switch inverter prototype and Altera Cyclone IV Field-programmable gate array.Öğe Dual-Hysteresis Torque Control of Multi-Induction Machines fed by a Nine-Switch Inverter(Ieee, 2021) Gulbudak, Ozan; Gokdag, MustafaThis paper presents a novel dual-hysteresis torque control method for multi induction motors fed by a nine-switch inverter. The proposed control method aims to control two separate induction motors with custom mechanical references. Stator current, mechanical speed, and torque are the control variables, and two motors are effectively controlled with the topology that contains a reduced number of switches. Instead of using two separate voltage-source inverters, a single nine-switch inverter guarantee a robust operation for applications where two mechanical loads are required to be controlled. Thus, the weight and size of the power stage are noticeably reduced which results in reliability improvement. The theoretical analyses and comprehensive design steps are presented and discussed. To verify the effectiveness of the proposed control method, the simulation results are presented.Öğe Dual-model predictive control of two independent induction motors driven by a SiC nine-switch inverter(Taylor & Francis Ltd, 2023) Gokdag, Mustafa; Gulbudak, OzanThis paper presents a finite control set model predictive control (FCS-MPC) approach for two induction machines driven by a nine-switch inverter (NSI). In the traditional approach, two separate voltage source inverters are necessary to drive the independent induction motors. In the proposed method, the nine-switch inverter is used to control the separate motors with a reduced number of switching devices compared to traditional method. A robust control strategy that eliminates the interactions between separate mechanical loads is required to achieve a proper independent speed and torque control for two induction machines through the NSI. To ensure the reliability of the machine operation, the indirect-field oriented control-based model predictive control strategy is proposed. The proposed control strategy is experimentally validated across the 3.2 kW SiC-based NSI prototype. The control algorithm is performed on an Altera Cyclone IV Field-programmable gate array. The experimental results demonstrate that the proposed dual-model predictive control method provides a good and robust motor control operation under different loading conditions. Two induction motors are successfully controlled, and the independent speed and torque control are achieved.Öğe Dual-sliding mode control of nine-switch inverter(Wiley, 2021) Gulbudak, Ozan; Gokdag, Mustafa; Komurcugil, HasanThis work introduces a novel dual-sliding mode control approach for nine-switch inverter topology. The nine-switch inverter helps regulate multiple ac-loads by using fewer semiconductor devices than the conventional two parallel voltage source inverter system. However, achieving independent control of two sets of ac loads is not a straightforward task when a nine-switch inverter feeds separate load stages. Regarding this consideration, a dual-sliding mode controller that includes a specific decision-making algorithm can be an efficient solution for a multi-load control problem. The proposed strategy offers a good compensation performance for the unconnected load stage under different load utilization profiles. The designed closed-loop system has a rapid response to sudden load change, and no unwanted interaction between individual load stages is observed. The detailed design steps and performance analyses are reported. Experimental results demonstrate the capability and usefulness of the proposed control strategy.Öğe Efficient FPGA-Based Real-Time Implementation of Model Predictive Control for Single-Phase Direct Matrix Converter(Taylor & Francis Inc, 2021) Gulbudak, Ozan; Gokdag, MustafaFinite control set model predictive control (FCS-MPC) is an optimal control strategy that solves user-defined objective functions to determine the best control action for the next time interval. Real-time implementations of model predictive control techniques are quite challenging for certain topologies due to computation complexities. In this paper, key aspects of achieving robust, reliable, and efficient field programmable gate arrays (FPGAs) based model predictive control are presented for single-phase direct matrix topology. The effectiveness of FPGA-based model predictive control is validated experimentally using an ALTERA Cyclone IV FPGA. Experimental results show that an effective load current control performance is obtained by taking advantage of pipelining capability of the FPGA device. The tradeoff between control bandwidth, FPGA resources, and hardware utilization is discussed.Öğe Enhancement of Steady-State Performance of PFC Boost Rectifier using Modulated Model Predictive Control(Ieee, 2023) Kranda, Enis; Gokdag, Mustafa; Gulbudak, Ozan; Prabaharan, NatarajanThis paper proposes a modulated-type predictive current control strategy for a single-phase power factor corrected boost rectifier. The conventional model predictive control strategy suffers from distorted input current and polluted power. Thus, a high sampling frequency is necessary to satisfy the utilization standards. However, the selection of a high sampling period demands significant computation power. Motivated by the drawbacks of the traditional model predictive control strategy, the modulation stage is added to the control loop and releases the trade-off between high sampling frequency requirement and total harmonic distortion to achieve good current quality. Fully benefits from the advantages of predictive model control, such as ease of implementation and high-speed dynamic response, are exploited while ensuring an acceptable power quality on a lower sampling frequency. The theoretical framework to support evidence-based practice is comprehensively explained. The proposed closed-loop design methodology is analytically revealed, and critical aspects of the proposed method are discussed. Numerous simulations work, including steady-state and transient operations, are performed to demonstrate the superiority of the proposed method by comparing it with the traditional model predictive approach. Finally, experimental validation is conducted to prove the feasibility of the proposed modulated predictive control method in real time.Öğe An Experimental Assessment of Predictive Current Control for Nine-Switch Inverter(Ieee, 2020) Gulbudak, Ozan; Gokdag, MustafaThis paper focuses on the experimental validation of model predictive control strategies for nine-switch inverter. The model-based control method is the control approach that has been gaining acceptance in the area of energy conversion systems. It is capable of handling nonlinear dynamics and controlling multi objectives. In this work, two different model predictive control approaches are introduced and experimental tests have been demonstrated that the proposed methods exhibit secured converter operation. The proposed optimization-based control strategies of the nine-switch inverter are fulfilled by a low-cost Field-Programmable Gate Array.Öğe Finite control set model predictive control approach of nine switch inverter-based drive systems: Design, analysis, and validation(Elsevier Science Inc, 2021) Gulbudak, Ozan; Gokdag, MustafaThis paper describes a model predictive control method for Nine-Switch Inverter (NSI)-based AC drive systems. Two separate three-phase AC loads (dual-output mode operation) or a single six-phase load (six-phase mode operation) can be connected to output terminals of an NSI. Three different Finite Control Set Model Predictive Control (FCS-MPC) strategies are presented and described. Firstly, dual-output mode FCS-MPC provides flexible control of detached load stages without any undesirable interaction. When disseminated loads are needed to be controlled, the output terminals of NSI are individually connected to separate load stages. Secondly, six-phase mode FCS-MPC provides robust control of six-phase load current. Thirdly, the predictive control scheme for controlling multiple induction machines is presented. Experimental and simulation tests have demonstrated that the proposed method exhibits a secured converter operation. The proposed predictive control strategies of Nine-Switch Inverter are accomplished using a Field Programmable Gate Arrays (FPGA). (C) 2020 ISA. Published by Elsevier Ltd. All rights reserved.Öğe FPGA Implementation of Model Predictive Control for Driving Multi-Induction Motors(Ieee, 2023) Gulbudak, Ozan; Gokdag, MustafaModel predictive control uses the system's explicit model to regulate the control goals. This control strategy is helpful in ac drive applications since it can handle multiple control goals and constraints. For induction motor applications involving multiple control targets, model predictive control provides convenience for real-time applications. This paper presents the FPGA implementation of the model predictive current control method to regulate two inductions motors fed by a nine-switch inverter. The control method aims to regulate the two independent induction motors' dynamics individually, and the real-time validation is conducted using a Cyclone IV FPGA. Experimental results are shared in the paper to explain how the system works. Detailed information is given about how the model predictive control method is implemented with an FPGA device. According to the experimental results, the system dynamics are quite stable, and the desired control targets have been achieved.Öğe FPGA-Based Hysteresis Current Control for Induction Motor fed by a Voltage-Source Inverter(Ieee, 2023) Gulbudak, Ozan; Gokdag, MustafaThis paper discusses FPGA implementation of the hysteresis current control strategy for an induction motor. The hysteresis control method is an on-off closed-loop strategy that has been used for a long time. What makes this control method interesting is the simplicity of the digital control application and the effortless design steps. This paper discusses implementing the hysteresis current control method using an FPGA. The closed-loop implementation is performed using Cyclone IV FPGA, and a detailed experimental study is carried out to evaluate the system's performance. The hysteresis current control strategy is investigated under steady-state and transient conditions.Öğe FPGA-Based Model Predictive Control for Power Converters(Ieee, 2020) Gulbudak, Ozan; Gokdag, MustafaModel predictive control is an optimization-based control approach that uses the mathematical description of the system. The predictive controller determines an ideal input sequence by calculating an objective function including nonlinear dynamics. Even though the predictive controller usually has a large control bandwidth and good steady-state performance, it entails a high computational burden. This shortcoming is the major problem for performing the predictive control method. In this work, the real-time implementation strategy of the predictive controller using field-programmable gate array is discussed. Three different power converters are considered as case studies and the presented strategy shows the effectiveness of field-programmable gate array to decrease the required execution time. The experimental results verify the theoretical investigations and inclusive comparison results are reported for different power converter topologies.Öğe Improving Grid Current Quality of Direct Matrix Converter for Induction Motor(Ieee, 2021) Gokdag, Mustafa; Gulbudak, OzanThis paper presents a novel predictive active damping strategy for controlling an induction motor fed by a direct matrix converter. In ac-ac drive applications, the grid current suffers from high distorted harmonics at low power levels. The high distortion negatively affects the power factor resulting in poor power quality. The proposed method offers an improvement in grid current quality when the induction motor operates at a lower than nominal power level. The predictive active damping method is integrated into the predictive torque control strategy, and the objective function is reformulated to achieve an effective damping performance. A comprehensive design step procedure is explained, and all theoretical analyses are verified by the simulation works. The results show that the proposed method is effective in reducing unwanted harmonics in grid current.Öğe Improving Supply Current Quality of Dual-Output Four-Leg Indirect Matrix Converter Using Model Predictive Control(Ieee, 2018) Gulbudak, Ozan; Gokdag, MustafaFinite Control Set Model Predictive (FCS-MPC) has been successfully applied to several power converter topologies and research on predictive control techniques has increased over the last few years. MPC method is an attractive to classical control methods because of its fast dynamic response and simple concept. MPC method uses the system discrete-model to calculate future values of the system variables for all possible control actions and computes a cost function related to control objectives to find its minimum. The switching action that minimizes the predefined cost function is selected to be applied for the next sampling period. This paper presents a supply current control technique for dual-output four-leg Indirect Matrix Converter (IMC) using the model predictive control approach. Two three-phase output load currents and the three-phase supply current can be controlled simultaneously by solving a single multi-objective cost function. In this work, simple predictive supply current control method is described and simulation results show that the proposed method performs quite well under steady-state and transient conditions.Öğe Lyapunov-based model predictive control of dual-induction motors fed by a nine-switch inverter to improve the closed-loop stability(Elsevier Sci Ltd, 2023) Gulbudak, Ozan; Gokdag, Mustafa; Komurcugil, HasanThis study presents a novel Lyapunov-based model predictive control strategy for a nine-switch inverter-based multi-drive system. The drive system includes two ac motors and a single nine-switch inverter (NSI) that is capable of feeding the multiple induction motors. The model predictive control (MPC) is a popular feedback strategy in ac-drive applications due to its fast dynamic characteristics and the skill of handling multiple control goals. Although the MPC offers a rapid dynamic response to load variations, it suffers from closed-loop instability when the cost function is poorly designed. The unwise choice of the tuning parameters, cost function terms, and control constraints cause instability resulting in poor system performance. In particular, the formulation of the selected objective function greatly impacts the closed-loop stability since it tailors the closed-loop characteristics. A simple penalization of the control goal error in the cost function may not ensure asymptotic stability. Motivated by the MPC stability problem, the cost function is reformulated as a Lyapunov energy function to strengthen the closed-loop stability in this paper. The proposed method selects the control input that meets the Lyapunov stability criterion and applies it to the multi-motor driver. The proposed strategy ensures asymptotic stability and provides a robust motor operation by introducing the Lyapunov control constraints. The proposed feedback strategy is experimentally verified using a lab-scaled hardware test platform. The experimental results demonstrate that the suggested control routine offers an improved steady-state characteristic compared to the conventional MPC method. (c) 2017 Elsevier Inc. All rights reserved.Öğe Model Predictive Control for Battery Charger Applications with Active Damping(Ieee, 2019) Gokdag, Mustafa; Gulbudak, OzanThis paper presents a model predictive control approach for a current source rectifier that can be used as battery charger fed from three-phase ac grid. The proposed MPC technique allows to charge the battery with a constant current or voltage as what is required for cyclic charge process of batteries. The proposed technique ensures unity input power factor operation for grid side. Instantaneous active and reactive power control combined with active damping technique is achieved to obtain safe charging process. The method does not require any input current sector information, and there is no need for sinusoidal input current reference synchronized with grid voltage. The proposed control method requires only active power demand to control whole system. A simulation study is carried out to observe the proposed method in terms of steady-state and dynamic responses and supply current quality.Öğe Model Predictive Control of AC-DC Matrix Converter with Unity Input Power Factor(Ieee, 2018) Gokdag, Mustafa; Gulbudak, OzanFinite Control Set Model Predictive Control (FCS-MPC) method is an attractive to classical control method because of its fast-dynamic response and simple concept. In MPC the future values of the system variables and a cost function employing control objectives are calculated for all possible control actions. The switching action that minimizes the predefined cost function is selected to be applied for the next sampling period. This paper presents a model predictive control approach to regulate the output voltage of an ac-dc Matrix Converter (MC) in an indirect manner by imposing sinusoidal supply currents. The dc output voltage and the three-phase supply currents can be controlled simultaneously by solving a single-objective cost function. In this work, simple predictive supply current control method is described, and simulation results show that the proposed method performs quite well under steady-state and transient conditions.Öğe Model predictive control of an indirect matrix converter with active damping capability(2020) Gokdag, Mustafa; Gulbudak, OzanIn this paper, a model predictive control (MPC) scheme is proposed to control indirect matrix converter (IMC), which is used for three phase-to-three phase direct power conversion without any intermediate energy storage component between them. The aim in the control of current source rectifier (CSR) stage of IMC is generally to have unity power factor with relatively low total harmonic distortion (THD). The aim in the control of voltage source inverter (VSI) stage is to be able to synthesize sinusoidal load currents with desired peak value and frequency. Imposed source current MPC technique in abc frame is used for the rectifier stage. An active damping technique without requiring the selection of an appropriate value for fictitious damping resistor is also included in the proposed control scheme in order to mitigate the resonance phenomenon of lightly damped input LC filter to suppress the higher order harmonics in supply currents. Load currents with desired peak and frequency are also obtained by imposing sinusoidal currents in abc frame. Two different cost functions are combined into a single cost function without any weighting factor since both error terms are in the same nature. The switching state that minimizes this pre-defined cost function among the 24-valid switching combinations of IMC is selected and applied to converter. The proposed model predictive control with active damping method shows a good performance in terms of THD levels in supply currents even at low current demands from supply side. The proposed strategy guarantees unity power factor operation and draws sinusoidal load currents at desired peak and frequency.
