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In this article, the coupled inductor is designed using a litz wire, an enameled litz wire, and a solid wire separately. All the coupled inductors wound with litz and solid wires are tested in a Cuk converter operated in DCM with a 25 kHz switching frequency for 15 W power, and winding losses of each wire, including proximity and skin effect loss, are calculated analytically without using any software, by using different techniques presented in literature, and the results are compared. Also, state-space modeling of the converter using a coupled inductor for DCM is derived as a contribution of the article because such a modeling is not derived for the Cuk converter in the literature. Thanks to the applications, inductor currents, switch voltage, input–output voltage, and output current are measured for coupled inductors with different wires. In addition, FEM simulation and co-simulation of all coupled inductors are realized, and the results obtained by applications are verified by them. Besides, it is shown that while the number of turns is the same, increasing the bundle of wires increases efficiency and inductance, reducing the window area and coupling coefficient. [ABSTRACT FROM AUTHOR]

The bidirectional DC-DC converter was selected as the research object. Based on the connection topology of energy storage and consumption components in the hybrid energy storage system, power demand indicators were determined for different energy flow directions, and the parameters of the main converter components and appropriate circuit components were established. A circuit model of buck/boost was constructed, and an adaptive fast terminal sliding mode control strategy was designed. The controller parameters were optimized using an improved genetic algorithm. Different control parameters have different control effects. In order to obtain better voltage output characteristics, the parameters of the adaptive fast terminal sliding mode control strategy were optimized.The proposed method can be verified to exhibit good control performance through simulation. [ABSTRACT FROM AUTHOR]

Renewable energy sources play a great role in the sustainability of natural resources and a healthy environment. Among these, solar photovoltaic (PV) systems are becoming more economically viable. However, as the utility of solar energy conversion systems is limited by the availability of sunlight, they need to be integrated with electrical energy storage systems to be more sustainable. This paper aims to improve the control performance of a hybrid energy storage system (HESS) with PV power generation as the primary power source. HESSs stabilize DC microgrid systems by compensating for demand generation mismatches. Batteries and supercapacitors are chosen as energy storage elements; batteries have a high energy density and are capable of supplying and absorbing energy over a long duration, while supercapacitors can store and deliver energy very quickly. To enhance the stability of the system, each storage element is connected to the DC bus using a bidirectional Ćuk converter, which offers high efficiency, a continuous current, and minimal switching losses. This study proposes a proportional–integral (PI) controller combined with the fast nonsingular integral terminal sliding mode control (FNITSMC) for HESSs to adjust the power balance in a DC microgrid. FNITSMC has the advantage of enhancing the system states to reach the equilibrium point of a long sliding surface with a fast convergence rate. The reference current for FNITSMC is obtained using a PI controller combined with a low-pass filter (LPF), which eliminates the peaking current spikes on the battery and diverts them towards the supercapacitor. The effectiveness of the proposed control scheme is validated through the real-time hardware-in-the-loop (HIL) simulations on Typhoon™ HIL-402 with added uncertainties, including load variations at various temperatures and irradiances. [ABSTRACT FROM AUTHOR]

Summary: Traditional multiple‐output AC‐DC power supply with power factor correction (PFC) function usually employs a two‐stage cascaded topology that is composed of prestage PFC converter and N independent poststage DC‐DC converters to achieve PFC and voltage or current regulation of N outputs. Hence, the conventional two‐stage cascaded multiple‐output AC‐DC power supply needs N + 1 magnetic components as power inductors or transformers and N + 1 controllers, which increases the cost and size of the multioutput converters. The conventional multiple‐string AC‐DC LED driving circuits usually employ a two‐stage topology to realize PFC and independent current regulation of each LED string. To address the issue of complexity, high cost, and large size of the two‐stage multistring LED driving circuit, a single‐stage triple‐output Cuk PFC converter is proposed by cascading boost converter and single‐inductor triple‐output buck converter with sharing main power switch in this paper. The topology operation principle, control strategy, design consideration, and operation characteristics of the proposed circuit are investigated in detail. With the switch sharing and inductor multiplexing technologies at the same time, the proposed converter utilizes only single‐stage converter to achieve PFC function, independent regulation of triple‐channel output current, and flicker‐free with low twice line frequency LED current ripple. The proposed converter is verified by a 50‐W experimental prototype of LED driver for triple string LEDs. The proposed converter only uses two power inductors and a set of controller to achieve greater than 0.945 PF, up to 90.5% efficiency, low LED current ripple, and independent current regulation for triple LED strings with different forward voltage, which may significantly reduce the cost and size of the traditional AC‐DC multistring LED driving circuit. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical analysis of steady-state operation, control-oriented modeling for voltage control, and the experimental results of a DC–DC bidirectional converter based on a Cuk converter using a voltage-doubler concept. Due to the voltage-doubler concept, the voltage stress across semiconductors is reduced when compared with the conventional Cuk converter; this allows for the use of semiconductors with reduced drain–source on-resistance. Moreover, due to the input and output current source characteristics, the converter presents advantages, such as draining/injecting currents on both sides with low-ripple currents. Furthermore, the theoretical analysis is verified by experimental results obtained from a proof-of-concept prototype designed with a 250 V input voltage, a 360 V output voltage, 2 kW rated power, and 100 kHz switching frequency. [ABSTRACT FROM AUTHOR]

Abstract Recently, the renewable energy applications require the development of highly efficient DC-DC converters with higher voltage transfer gain capability to meet out the increased global power demand. The non-isolated DC-DC converters are preferred due to certain drawbacks of isolated structures. The traditional boost, SEPIC (single-ended primary-inductor converter), and CUK based DC-DC converter structures are modified with additional power switches, diodes, and passive components in order to achieve high voltage gain. However, the modified structures with large number of active and passive elements suffer from the drawbacks of increased complexity of control algorithm, reduced power conversion efficiency and higher converter cost. Hence, the researchers started to explore more on single power switch configured non-isolated high step-up DC-DC converter topologies using hybrid concept. The research work presented in this paper explores such a high gain single-switch hybrid DC-DC converter structure that combines the conventional SEPIC and CUK topologies to achieve enhanced voltage gain. In the proposed hybrid topology, the input current is continuous during all modes of converter operation. Moreover, the power switch experiences only low voltage-current stress. The closed-loop configuration of the proposed hybrid converter is implemented using classic PID (Proportional+Integral+Derivative) and FOPID (Fractional Order PID) controllers, and simulated in MATLAB / SIMULINK environment with duty ratio D = 0.7 for the power switch. The results demonstrate that the dynamic performance of the converter with FOPID controller is much improved in terms of reduced settling time, overshoot, and ripples for the output voltage, as compared to that with classic PID controller.

The problem of voltage regulation in power systems has been well studied. There exist numbers of stabilization model discussed in literature which consider input and output voltage. The methods suffer to achieve higher performance in power stabilization. To handle this issue, an efficient Real-time Capacitance and Absorption based voltage regulation model (RCAVRM) is presented in this paper. The model has been fabricated with different MOFSET and cuk converter connected in serial where the Mofset are designed to maintain the traces of voltage present in different capacitors and inductors. At each duty cycle, the method collects the number of circuits being used and number of other circuits not triggered. Based on these details, the method computes Capacitance Power Stabilization Factor (CPSF) and Voltage Absorption Factor (VAF). Using these two factors, the method computes the value of power stabilization weight (PSW) for different circuits. Based on the value of PSW, a unique circuit is selected to regulate the power supply to the electric system. The proposed model improves the performance of power stabilization with least voltage loss.

This paper presents a theoretical analysis of steady-state operation, control-oriented modeling for voltage control, and the experimental results of a DC–DC bidirectional converter based on a Cuk converter using a voltage-doubler concept. Due to the voltage-doubler concept, the voltage stress across semiconductors is reduced when compared with the conventional Cuk converter; this allows for the use of semiconductors with reduced drain–source on-resistance. Moreover, due to the input and output current source characteristics, the converter presents advantages, such as draining/injecting currents on both sides with low-ripple currents. Furthermore, the theoretical analysis is verified by experimental results obtained from a proof-of-concept prototype designed with a 250 V input voltage, a 360 V output voltage, 2 kW rated power, and 100 kHz switching frequency.