In this paper, a new nonisolated high step-up dc–dc converter is proposed. Active–passive inductor cells (APICs) are used to extend the topology. The ability to achieve high gains is the main merit of the proposed topology. The proposed converter operates based on parallel charging and series discharging of the inductors. The converter also achieves high step-up voltage gain with appropriate duty cycle and low voltage and current stress on the power switches and diodes. The proposed converter is analyzed in operation modes. The main parameters of the converter such as voltage gain, voltage stress of semiconductor devices are calculated to compare with other structures. Considering the output voltage ripple and filter size, the proposed converter is designed. Moreover, the losses and efficiency of the converter are calculated. The performance of the proposed converter is validated by experimental results.

Extendable Nonisolated High Gain DC–DC Converter Based on Active–Passive Inductor Cells

Many different types of electric vehicle (EV) charging technologies are described in literature and implemented in practical applications. This paper presents an overview of the existing and proposed EV charging technologies in terms of converter topologies, power levels, power flow directions and charging control strategies. An overview of the main charging methods is presented as well, particularly the goal is to highlight an effective and fast charging technique for lithium ions batteries concerning prolonging cell cycle life and retaining high charging efficiency. Once presented the main important aspects of charging technologies and strategies, in the last part of this paper, through the use of genetic algorithm, the optimal size of the charging systems is estimated and, on the base of a sensitive analysis, the possible future trends in this field are finally valued.

/pdf/electric-vehicles-charging-technology-review-and-optimal-1oewmefr4x.pdf

Electric Vehicles Charging Technology Review and Optimal Size Estimation

Recent advancements in renewable energy have created a need for both high step-up and high-efficiency dc–dc converters. These needs have typically been addressed with converters using high-frequency transformers to achieve the desired gain. The transformer design, however, is challenging. This paper presents a high step-up current fed converter based on the classical Cockcroft–Walton (CW) multiplier. The capacitor ladder allows for high voltage gains without a transformer. The cascaded structure limits the voltage stresses in the converter stages, even for high gains. Being current-fed, the converter (unlike traditional CW multipliers) allows the output voltage to be efficiently controlled. In addition, the converter supports multiple input operation without modifying the topology. This makes the converter especially suitable for photovoltaic applications where high gain, high efficiency, small converter size, and maximum power point tracking are required. Design equations, a dynamic model, and possible control algorithms are presented. The converter operation was verified using digital simulation and a 450-W prototype converter.

High Gain DC–DC Converter Based on the Cockcroft–Walton Multiplier

Generally, an LLC series resonant converter ( LLC SRC) is an attractive topology for applications, which require wide input variation and high conversion efficiency because of its wide gain capability and soft-switching capability. However, there is a regulation problem in which the output voltage increases as the load current decreases. In this paper, Bode plot and impedance asymptote analysis were conducted to obtain an intuitive sense of the regulation characteristic of LLC SRC under the light-load condition. Moreover, to improve the regulation capability, a new resonant tank with an additional capacitor is proposed. Its design guidelines were determined by Bode plot and impedance asymptote analysis. Therefore, the proposed LLC SRC achieves very light load regulation, while it maintains the advantages of typical LLC SRCs.

Improving the Light-Load Regulation Capability of LLC Series Resonant Converter Using Impedance Analysis

In this study, a new non-isolated high step-up DC-DC converter is presented with high-voltage gain which is suitable for renewable applications. The proposed converter uses coupled inductor and voltage multiplier cell (diode capacitor) for increasing the voltage level. The voltage gain of the proposed converter can be increased by selecting the appropriate turns ratio of coupled inductor. Voltage multiplier cell consists of two diodes and two capacitors which are used to obtain high-voltage gain. The diode-capacitor cell is used as a clamp circuit, which leads to reducing the voltage stress across the semiconductors. The proposed converter has a single power switch which causes the control of the proposed converter is simple. Also, the power switch is used with lower ON-state resistant (
 R
 DS-ON
). The zero-current switching of the diode is obtained in OFF state. Therefore, the conduction losses are decreased with lower normalised voltage stress across semiconductors. To prove the performance of the proposed converter, theoretical analysis and comparison with other converters are provided. To confirm the benefits of the proposed converter, a laboratory prototype with 20 V input voltage, 200 V output voltage and about 200 W power level at operating 25 kHz is built and tested.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2018.5414

High step-up DC–DC converter with coupled inductor suitable for renewable applications

This paper proposes a soft-switched single switch isolated converter. The proposed converter is able to offer low cost and high power density in step-up application due to the following features: zero-current switching (ZCS) turn-on and zero-voltage switching (ZVS) turn-off of switch and ZCS turn-off of diodes regardless of voltage and load variation; low rated lossless snubber; reduced transformer volume compared to flyback-based converters due to low magnetizing current. Experimental results on a 100 kHz, 250 W prototype are provided to validate the proposed concept.

A Fully Soft-Switched Single Switch Isolated DC–DC Converter

This paper proposes a new parallel loaded resonant converter operating in a narrow switching frequency under wide output voltage range The proposed converter is capable of operating under zero-voltage switching turn- on of switches and zero-current switching turn- off of diodes Also, the resonant capacitor with feasible capacitance and current rating can be selected by adjusting the turn ratio of the transformer, making the proposed converter more realizable in high power application Further, the proposed converter has zero voltage gain at notch resonant frequency, and therefore there are no current and voltage stress in the resonant tank during start-up Experimental results from a 3-kW prototype are provided to validate the proposed concept

New Parallel Loaded Resonant Converter With Wide Output Voltage Range

This paper proposes a new single-stage electrolytic capacitor-less ac-dc converter with sinusoidal charging for EV battery chargers. The proposed converter has simple circuit structure with reduced component count. It achieves ZVS turn-on of all switches and ZCS turn-off of all diodes. Requiring no input filter due to CCM operation and bulky electrolytic capacitors, and having no low frequency component in the transformer the proposed converter is able to achieve high power density. A 2-kW prototype of the proposed converter has been built and tested to verify the validity of the proposed operation.

A reduced component count single-stage electrolytic capacitor-less battery charger with sinusoidal charging

This paper proposes a new single-stage ac-dc converter with high frequency isolation which is suitable for on-board EV/PHEV chargers. The proposed single-stage structure does not have a diode bridge at the input stage and electrolytic capacitor at the dc-link. The two single-phase full-bridge converters play a double role as both ac-dc converter for PFC and the primary-side circuit of the isolated dc-dc converter. They are configured such that the fundamental components of the chopped ac voltages are cancelled at the primary winding voltage of the transformer, thus reducing magnitude of the magnetizing current which results in reduced volume and core loss. Also, the proposed converter can achieve ZVS turn on of switches and ZCS turn off of diodes. A 3-kW prototype of the proposed converter is built and tested to verify the validity of the proposed operation.

Single-stage electrolytic capacitor-less AC-DC converter with high frequency isolation for EV charger

This paper proposes a single switch soft switching isolated converter. The proposed converter is able to offer low cost and high power density in high step up application due to the following features: ZCS turn on and ZVS turn off of switch and ZCS turn off of diodes regardless of voltage and load variation; simple gate driver circuit and low rated lossless snubeer; reduced transformer volume compared to flyback or forward based converters due to low magnetizing current. Experimental results on a 100kHz, 250W prototype are provided to validate the proposed concept.

Minjae Kim

Papers

A Fully Soft-Switched Single Switch Isolated DC–DC Converter

New Parallel Loaded Resonant Converter With Wide Output Voltage Range

A reduced component count single-stage electrolytic capacitor-less battery charger with sinusoidal charging

Single-stage electrolytic capacitor-less AC-DC converter with high frequency isolation for EV charger

A fully soft-switched single switch isolated DC-DC converter