The rapid consumption of fossil fuel and increased environmental damage caused by it have given a strong impetus to the growth and development of fuel-efficient vehicles. Hybrid electric vehicles (HEVs) have evolved from their inchoate state and are proving to be a promising solution to the serious existential problem posed to the planet earth. Not only do HEVs provide better fuel economy and lower emissions satisfying environmental legislations, but also they dampen the effect of rising fuel prices on consumers. HEVs combine the drive powers of an internal combustion engine and an electrical machine. The main components of HEVs are energy storage system, motor, bidirectional converter and maximum power point trackers (MPPT, in case of solar-powered HEVs). The performance of HEVs greatly depends on these components and its architecture. This paper presents an extensive review on essential components used in HEVs such as their architectures with advantages and disadvantages, choice of bidirectional converter to obtain high efficiency, combining ultracapacitor with battery to extend the battery life, traction motors’ role and their suitability for a particular application. Inclusion of photovoltaic cell in HEVs is a fairly new concept and has been discussed in detail. Various MPPT techniques used for solar-driven HEVs are also discussed in this paper with their suitability.

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A comprehensive review on hybrid electric vehicles: architectures and components

Using multi-input converters (MICs) in hybrid energy storage systems (HESSs) presents several advantages, such as low component count, control simplicity, and fully control of source energies. The power levels of sources in these systems need to be determined wisely by an energy management strategy (EMS). This paper presents an EMS for a battery/ultracapacitor (UC) HESS including a bidirectional MIC for electric vehicles (EVs). Thanks to the fact that energy flow between battery and UC is free in this MIC, the proposed EMS not only regulates the state-of-charge of UC but also smooths the battery power profile by using a fuzzy logic controller and a rate limiter. Therefore, it results in a sustainable HESS with longer battery life. Through a simulation study and an experimental setup including a real EV, the performance of the proposed system is evaluated comprehensively. Then, based on experimental results, battery cycle-life improvement due to the battery/UC hybridization is explored.

An Energy Management Strategy for a Concept Battery/Ultracapacitor Electric Vehicle With Improved Battery Life

Energy sources and multi-input DC-DC converters used in hybrid electric vehicle applications – A review

In this paper, a hybrid switched-capacitor/switched-quasi-Z-source bidirectional dc–dc converter is proposed for electric vehicles (EVs) with hybrid energy sources, which has a wide voltage gain range in the bidirectional energy flows. Compared with the traditional quasi-Z-source bidirectional dc–dc converter, the proposed converter only changes the position of the main power switch and employs a switched-capacitor cell at the output of the high-voltage side. Therefore, the advantages of the wide voltage gain range and the lower voltage stresses across the power switches can be achieved. The operating principle, the voltage and current stresses across the power switches, and the comparisons with other converters are analyzed in detail. Furthermore, the parameter design of the main components, the dynamic modeling analysis, and the voltage control scheme are also presented. Finally, the experimental results obtained from a 400 W prototype validate the characteristics and the theoretical analysis of the proposed converter.

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Hybrid Switched-Capacitor/Switched-Quasi-Z-Source Bidirectional DC–DC Converter With a Wide Voltage Gain Range for Hybrid Energy Sources EVs

This paper proposes a novel integrated synchronous buck converter for the auxiliary power supply system of electric vehicles, which achieves multiple independently regulated outputs with reduced switching components in comparison with the conventional separate buck converters. In order to obtain a better understanding of the proposed converter, operational principle and performance characteristics of a simplified dual-output buck converter are introduced in detail, as an example. The analysis shows that zero-voltage-switching operation and lower conduction losses could be attained. In addition, its dynamic behavior is similar to the conventional buck converter and thus the controller design is simple. Finally, experimental results based on a prototype circuit in which two inductors are integrated into one magnetic core to achieve further reduced cost are demonstrated to verify the advantages.

Integrated Multiple-Output Synchronous Buck Converter for Electric Vehicle Power Supply

To process the power in hybrid energy systems using a reduced part count, researchers have proposed several multiinput dc–dc power converter topologies to transfer power from different input voltage sources to the output. This paper proposes a novel bidirectional nonisolated multi-input converter (MIC) topology for hybrid systems to be used in electric vehicles composed of energy storage systems (ESSs) with different electrical characteristics. The proposed converter has the ability to control the power of ESSs by allowing active power sharing. The voltage levels of utilized ESSs can be higher or lower than the output voltage. The inductors of the converter are connected to a single switch; therefore, the converter requires only one extra active switch for each input, unlike its counterparts, hence resulting in reduced element count. The proposed MIC topology is compared with its counterparts concerning various parameters. It is analyzed in detail, and then, this analysis is validated by simulation and through a 1-kW prototype based on a battery/ultracapacitor hybrid ESS.

A Bidirectional Nonisolated Multi-Input DC–DC Converter for Hybrid Energy Storage Systems in Electric Vehicles

This work presents a multi-input converter (MIC) that can build a DC microgrid having renewable energy resources, balanced sources, and energy storage devices. After analysing its operation modes, a design procedure for the converter considering three different cases is provided. This procedure includes the semiconductor elements selection and design of the inductors. After this step, a detailed efficiency analysis is carried out for the studied cases. Finally, a 1 kW prototype creating a photovoltaic–battery system is built. Through several experiments based on this set-up, it is shown that the theoretical analysis is accurate and the studied MIC can be successfully utilised to create DC microgrid.

Analysis and experimental verification of a multi-input converter for DC microgrid applications

In this work, the utilization of a Photovoltaic (PV) array and a battery pack in parallel via a double input DC/DC converter including a coupled inductor is reported. The dynamic performance of this proposed hybrid energy system is analyzed in detail through the switching model created in MATLAB
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Simulink
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environment by using PLECS
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power components under different solar irradiance and demanded load levels.

Yakup Tavlasoglu

Papers

A Bidirectional Nonisolated Multi-Input DC–DC Converter for Hybrid Energy Storage Systems in Electric Vehicles

An Energy Management Strategy for a Concept Battery/Ultracapacitor Electric Vehicle With Improved Battery Life

Analysis and experimental verification of a multi-input converter for DC microgrid applications

PV/battery hybrid energy system via a double input DC/DC converter for dynamic loads