Browsing by Author "Balta, Guven"

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Artificial Intelligence Based Switching Frequency Regulation with Fast Terminal Sliding Mode Control for DC-DC Step-Down Converters
(Pergamon-Elsevier Science Ltd, 2023) Balta, Guven; Hisar, Cagdas; Altin, Necmi
Making the best voltage/current regulation against disturbances and uncertainties and, most importantly, to minimize chattering effect in power electronics circuits, the hysteresis modulation based (HM) sliding mode control (SMC) is widely used. There are various research on this subject in the literature. However, the variable switching frequency that HM-SMC brought about has regrettably overlooked in the majority of these research. This problem is addressed in depth in this paper by demonstrating how the switching frequency is affected by various factors. Next, the fuzzy logic control (FLC) is proposed for the first time as a solution for switching frequency regulation in a power electronics circuit. The proposed FLC for switching frequency regulation fortifies the system described in this study and sets it apart from many other HM-SMC studies in the literature with its advantages against the difficulties caused by variable switching frequency such as excessive switching and driver power losses. On the other hand, the fast terminal SMC (FTSMC) which has significantly superior convergence performance than its counterparts, has been recommended for voltage regulation. The proposed FTSMC technique employs only one voltage sensor different from the past literature. This simplifies the proposed control mechanism in practical implementation and also makes the system economical. The two proposed controllers' compatibility with one another has been tested through experimental tests, including the steady-state condition, variations in switching frequency reference value, step change of load resistance, output voltage reference value variation, and finally step change of input voltage. The outcomes of the experiments demonstrate that the switching frequency and output voltage are successfully regulated with good dynamic and steady state performance. Finally, the proposed techniques have been compared with six recent approaches from the existing literature to highlight their performance.
Integral Sliding Mode Controlled 3L-ANPC Based Bidirectional AFE Converter for DC Microgrids
(IEEE, 2024) Hisar, Cagdas; Balta, Guven; Sera, Ibrahim; Altin, Necmi; Ozdemir, Saban; Nasiri, Adel
In this paper, an integral sliding mode controller is proposed for a bidirectional 3-level ANPC-based Active Front End (AFE) converter. An integral error term is added to the control law to reduce the steady state error and chattering. Thus, the reference tracking performance of the controller is improved. The high-frequency space vector PWM technique is used for the bidirectional 3-level AFE. Considering the output waveforms with low THD of the 3-level ANPC, only L filters are used at the converter output. The whole system is simulated in MATLAB/Simulink environment. The obtained simulation results show that the proposed system provides high transient response and zero steady state error. Besides, the grid current harmonics are low in both directions of operation.
Modified Fast Terminal Sliding Mode Control for DC-DC Buck Power Converter with Switching Frequency Regulation
(Wiley, 2022) Balta, Guven; Guler, Naki; Altin, Necmi
In this paper, a modified fast terminal sliding mode control (FTSMC) with a fixed switching frequency is proposed for regulating the output voltage of the DC-DC buck converters. The design steps of the proposed FTSMC such as the selection of sliding surface, switching control strategy, existence, robustness, and stability analysis are presented in detail. To overcome the variable switching frequency in FTSMC, a frequency control loop is designed. Moreover, the proposed FTSMC with fixed switching frequency can be implemented by using only one voltage sensor. Hence, the proposed control method not only offers a fast dynamic response and fixed switching frequency but also simplifies the controller design in practical implementation. The effectiveness of the proposed control methods has been investigated by experimental studies. The results reveal that the proposed methods exhibit a good performance under both steady-state and dynamic transients caused by the variations in load resistance, input voltage, and reference voltage. Moreover, the proposed method is compared with four existing methods.
A New Singularity Problem Solved Fast Terminal Sliding Surface with Fixed Switching Frequency for DC-DC Converters
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Hisar, Cagdas; Balta, Guven; Sefa, Ibrahim; Altin, Necmi
Compared to other control types, Sliding-Mode Control (SMC) offers a more unbounded design potential in addition to its high precision, simplicity, robustness, rapid response, and insensitivity to disturbances within a given range. Using the design freedom feature, this study proposes a novel fast terminal sliding surface, which is one of the new generation surfaces of SMC. By comparing the new surface with its counterparts in the literature, it has been shown with simulation data how effective it is in obtaining fast dynamic responses. Furthermore, the new sliding manifold solves the singularity problem associated with fast terminal sliding surfaces and this is detailed by theoretical analyses. From an experimental perspective, the suggested surface is tested on a step-down DC-DC converter. To ensure that the converter operates at a fixed switching frequency, parabolic modulation (PM), which is given as a novel approach in the literature and directly creates the switching signal, is utilized. To highlight the importance of PM, the system is also run with hysteresis modulation (HM). The system is subjected to a variety of disturbances, and dynamic results are obtained separately for both PM and HM. The relevant experimental outcomes show that the innovative surface successfully controlled the converter's state variable in both dynamic and steady-state conditions. Experimental results further reveal that the fixed switching frequency is obtained with the PM approach.
Sliding Mode-Based Active Damping Control of LCL-Filtered Three-Phase PWM Rectifier
(Springer Heidelberg, 2025) Hisar, Cagdas; Balta, Guven; Sefa, Ibrahim; Altin, Necmi
This paper presents a sliding mode control (SMC) approach for active damping to a three-phase LCL-filtered unity power factor PWM rectifier. A multi-loop framework is applied in controller design to achieve fast dynamic response, good tracking ability and damp the LCL filter's resonance. The inner loop ensures active damping by sensing filter capacitor voltage. A sliding mode controller is employed in this layer. In the mid-loop of the proposed multi-loop framework, PI controllers in the synchronous reference frame are used to continue the unity power factor easily. Thus, the efficient use of PI controllers to generate line current references in the mid-loop is enabled. Also, another sliding mode controller is used in the outer loop to control the DC voltage and achieve enhanced dynamic response. The performance of the proposed strategy has been validated with simulation and experimental studies. Besides, the proposed system is compared with the conventional synchronous reference frame PI-controlled PWM rectifier. The results demonstrate that the system's dynamic response is faster than the PI-controlled system. It is also seen that the resonance occurred by the complex conjugate poles of the LCL filter is successfully damped by the SMC-based inner controller. This controller eliminates the damping resistor use and related power loss as well. Besides, the harmonic components of the input current meet the IEEE 519 standard and unity power factor operation is ensured.