In this article, we propose an extendable quadratic bidirectional dc–dc converter that has an improved voltage transfer ratio (VTR) with the capability of redundancy and modularity for electric vehicle applications. As n modules are embedded, its VTR becomes n times higher for both directions of currents. Furthermore, the common electrical ground between the input and output is preserved. This is a simple structure with the lowest rating of semiconductors in the family of quadratic bidirectional converters leading to ease of control ability. The proposed converter performance is evaluated in both power flow direction using the deadbeat controller, which is a smooth, accurate, and fast response. Finally, the process of charging/discharging of a lithium-ion battery is controlled through the proposed converter. 500-W experimental results are provided in both power flow directions in a closed-loop system in the presence of the proposed controller. The obtained results verify the applicability of this structure.

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An Extendable Quadratic Bidirectional DC–DC Converter for V2G and G2V Applications

This article proposes a new wide-range bidirectional dc–dc converter that has an improved voltage gain transfer ratio for use in electric vehicle (EV) applications. The converter preserves the common electrical ground between input and output terminals, and presents a low-voltage stress of switches, high utilization factor, and high efficiency. The proposed EV charger performance is evaluated for a bidirectional power flow in grid-connected vehicle-to-grid (V2G) and grid-to-vehicle (G2V) modes. The converter uses a dead-beat current controller in the dc–dc and dc–ac stages, which has a smooth, accurate, and fast response. Finally, experimental results for a 500 W, 40–200 V prototype are provided under a bidirectional power flow in a closed-loop system in the presence of the proposed dead-beat controllers. The obtained results substantiate the theoretical analysis and the applicability of this structure. The converter exhibits the capability for EV battery charging/discharging and demonstrates a peak efficiency of 97.2% and 96.8% in the step-down and step-up modes of operation, respectively. 

A Wide-Range High-Voltage-Gain Bidirectional DC–DC Converter for V2G and G2V Hybrid EV Charger

Bidirectional DC/DC converters are so prevalent in several applications. Regarding some applications, increasing their voltage gain ratios (VTR) are quite important. So, this paper proposes a novel extendable bidirectional boost-buck converter. In this converter, any isolation and coupled inductors are not employed. Each stage is derived from fundamental bidirectional boost/buck converter with the same switching algorithms. By embedding $n$ stages in topology, VTRs for step-up/step-down are multiplied $n$ times for step-down and step-up modes. Furthermore, a comprehensive comparison have provided in case of VTR and total voltage stress across active power switches. It can be seen that total voltage stress of active power switches (TVSAPS) is much lower than the other relevant structures. The feasibility of this architecture has successfully examined by PSIM simulation and detected experimental outcomes from prototype laboratory set up.

A Novel High Gain Extendable DC-DC Bidirectional Boost-Buck Converter

In this paper, a minimum-phase response fourth-order boost dc-dc converter (FBDC) exhibiting continuous input and output current is proposed. A voltage-mode controller is adopted to this converter to perform bus voltage regulation in a low voltage low power dc distribution system (LVPDS). FBDC supports additional load demand by interconnecting a second power source/battery. A systematic steady-state analysis for FBDC is established and the ripple content and other L-C design expressions are derived. The LVPDS is an integration of solar photovoltaic (PV) source using a conventional dc-dc boost converter (CBDC), and constant power load using a conventional dc-dc buck converter (CBuC). In this LVPDS, the FBDC primarily ensures dc bus voltage regulation, CBDC ensures the maximum power point tracking (MPPT) while CBuC regulates the load voltage. Various transfer function models, formulated through small-signal analysis, are used to address the controller design aspects and interconnected LVPDS stability issues. A generalized small-signal model of LVPDS is also developed to analyze the sub-system interactions arising during the coherent operation of BRC in this multi-converter system. The impact of connecting FBDC, as BRC, with other converters in the LVPDS is also analyzed. The laboratory prototype of a 48 V LVPDS is developed for experimental validation of bus voltage regulation and sub-system interactions. The theoretical and experimental results are found to be in close correlation with each other.

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Non-Isolated Fourth-Order Boost DC-DC Converter for Power Management in Low Voltage Low Power DC Grids: Design and Interaction Analysis

This article proposes a bidirectional battery charger for grid to vehicle and vehicle to grid operations of electric vehicles (EV). The dc stage of the proposed converter offers a quadratic buck–boost voltage gain ratio, which makes it suitable for interconnecting the battery pack unit of EVs with both dc and ac grids as a home EV charger. A high-voltage gain ratio, low voltage, and current stress of switches, high values of utilization factors (UF) for both directions are achieved. Continuous input current and common electrical ground are preserved at the dc–dc stage and also, the continuous output current of the proposed converter makes the realization of the pseudo dc-link method possible for connecting to an ac grid. Consequently, the switching power loss in the dc–ac stage of the EV charger is reduced, and as a result, it allows the proposed charger to run more efficiently and cooler. The operating principle, steady-state characteristics including the current, voltage stress, and UF of the switches, and comparison with other state-of-the-art dc–dc bidirectional converters are carried out in detail. Finally, to verify the theoretical achievements, a 500-W laboratory prototype of the proposed EV charger is implemented. The EV charger exhibits the capability for ac and dc regulation and demonstrates peak efficiency of 97.8% in the forward and 97.5% in the backward direction modes of operation. 

Pseudo DC-Link EV Home Charger With a High Semiconductor Device Utilization Factor

This paper proposes, a bidirectional battery-charger for grid-to-vehicle and vehicle-to-grid operations of electric-vehicles (EV). The DC stage of the proposed converter offers a quadratic buck-boost voltage-gain ratio, which makes it suitable for interconnecting the battery pack unit of EVs with both DC and AC grids as a home EV-charger. A high voltage-gain, low voltage and current stress of switches, high values of utilization-factors (UF) for both directions are achieved. Continuous-input current and common-electrical-ground are preserved and also, the continuous-output current of the proposed converter makes the realization of the pseudo-DC-link method possible for connecting to an AC grid. Consequently, the switching power loss in the DC-AC stage of the EV-charger is reduced, and as a result, it allows the proposed charger to run more efficiently and cooler. The operating principle, steady-state characteristics including the current, voltage stress and UF of the switches, and comparison with other state-of-the-art DC-DC bidirectional converters are carried out in detail. Finally, to verify the theoretical achievements, a 500-W laboratory prototype of the proposed EV-charger is implemented. The EV-charger exhibits the capability for AC and DC regulation and demonstrates peak efficiency of 97.8% in the forward and 97.5% in the backward direction modes of operation.

Pseudo DC-link EV Home Charger with a High Semiconductor Device Utilization Factor

The fundamental DC-DC boost converter has the drawbacks of low voltage gain ratio followed by discontinuous output current. May the reverse recovery problem rises as a disaster for the output diode along with harming the power switch. Also the stress of voltage is significantly high in respect with the output voltage. Therefore, a new topology of high gain non-isolated DC-DC boost converter is proposed in this paper. In this converter a high voltage gain is achieved with continuous power in the input and the output. The voltage stresses across the semiconductors are all less than that of fundamental boost converter in respect with the output voltage. Only a single power switch is controlled by PWM which leads to simplicity and cost reduction. The proposed converter is advisable for PV panels because of its continuous input current. Furthermore, as the output current is also continuous this makes it a suitable choice for fuel cells. Simulations are provided in MATLAB Simulink to verify the extracted theoretical equations from the proposed converter.

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A New High Gain DC-DC Boost Converter with Continuous Input and Output Currents

In this paper, a novel structure for a high gain single-switch buck-boost converter with continuous input and output power suitable for renewable energies connected to the distribution grid is proposed and illustrated. Unlike traditional buck-boost, CUK, SEPIC and ZETA converter, the proposed converter has continuous currents by the help of inductive filters in its input and output ports. Therefore, this converter is suitable for renewable energy utilization. Without using any galvanic isolations or either coupled inductors with only a single power switch with low stress on, the proposed converter has significant higher voltage gain compared to the other relevant buck-boost converters. In this converter, low numbers of elements are used to avoid high costs and complexity. In order to validate the theoretical equations, simulation results are provided in buck and boost modes in PSIM software.

Seyed Hossein Hosseini

Papers

An Extendable Quadratic Bidirectional DC–DC Converter for V2G and G2V Applications

Pseudo DC-link EV Home Charger with a High Semiconductor Device Utilization Factor

A New High Gain DC-DC Boost Converter with Continuous Input and Output Currents

A Novel High Gain Extendable DC-DC Bidirectional Boost-Buck Converter

A Novel High Gain Single-Switch DC-DC Buck-Boost Converter with Continuous Input and Output Power