Search

This paper presents a new soft switching high voltage gain interleaved dc-dc converter with a three-windings coupled inductor for a fuel cell vehicle. Two interleaved and intercoupled boost cells are connected by the input parallel and output series (IPOS) configuration, realizing low input current ripple and high voltage gain simultaneously. All power switches can operate under soft switching conditions by only adding a simple auxiliary circuit composed of one auxiliary inductor and one power switch. Besides, the auxiliary inductor is coupled with the main inductors, which results in a rapid zero convergence of the auxiliary current and a small conduction loss of the auxiliary circuit. The operating principle, steady state characteristic, comparison with other converters, and parameter design are analyzed in this paper. Finally, the main characteristics of the proposed converter are verified by a 1-kW laboratory prototype. [ABSTRACT FROM AUTHOR]

The DC-DC converter for fuel cell vehicles should be characterized by high-gain, low voltage stress, small size and high-efficiency. However, conventional two-level, three-level and cascaded boost converters cannot meet the requirements. A new non-isolated DC-DC converter with switched-capacitor and switched-inductor is proposed in this paper, which can obtain high-gain, wide input voltage range, low voltage stresses across components and common ground structure. In this paper, the operating principle, component parameters design, and comparisons with other high-gain converters are analyzed. Moreover, the state-space averaging method and small-signal modeling method are adopted to obtain the dynamic model of converter. Finally, simulation and experimental results verify the effectiveness of the proposed topology. The input voltage of the experimental prototype ranges from 25 V to 80 V. The rated output voltage is 200 V and rated power is 100W. The maximum efficiency is 93.1% under rated state. The proposed converter is suitable for fuel cell vehicles. [ABSTRACT FROM AUTHOR]

In order to match voltages between the fuel cell stacks and the DC link bus of fuel cell vehicles, a single-switch Boost dc–dc converter with diode-capacitor modules is proposed in this paper. The capacitors are charged in parallel and discharged in series. The wide voltage-gain range can be obtained by using a simple structure. In addition, the basic operating principles, the extended stages, the fault tolerant operation, and steady-state characteristics of the converter are analyzed and presented in this paper, and the small-signal model is also derived. A 400 V, 1.6 kW experimental prototype is developed, and the wide voltage-gain range (3.3 ∼ 8) is demonstrated with a maximum efficiency at 97.25%. The experimental results validate the effectiveness and feasibility of the proposed converter and its suitability as a power interface for fuel cell vehicles. [ABSTRACT FROM PUBLISHER]

The essential features of a DC–DC converter for fuel cell vehicle are to ensure the higher voltage gain to meet out the higher DC link voltage demand, continuous input current to improve the life span of the fuel cell, presence of common grounding to avoid electromagnetic interference issue and lower voltage stress with reduced components. This paper presents a high voltage gain DC–DC converter by combining the switched capacitor and quasi switched boost network modules. The proposed high voltage gain converter provides the continuous input current, lower voltage stress, utilizes a fewer number of elements and common grounding feature. The operating characteristics, steady-state analysis both in continuous current mode (CCM) and discontinuous current mode (DCM), comparative analysis with contemporary converters are discussed. The theoretical claimed analysis is validated by the simulation and experimental study. The proposed converter is operated for 200 W output power rating and tested for providing the voltage gain in the range of 5–8 times the input voltage gain by varying the input voltage from 25 V–40 V. The efficiency of the proposed converter is also reported for different output power rating which is in the range 91.3%–93.7%. [ABSTRACT FROM AUTHOR]

LLC resonant converters are widely used in On-board Power Converter but the pumping voltage of traditional LLC converter is unavoidable under light-load conditions due to the existence of parasitic parameter. In this paper, an LLC resonant converter with damping split inductor is proposed to improve the light-load regulation capability. The original resonant inductor is divided into two parts in series. Then, a simple damping resistor connected on one part in parallel and the other part can be integrated into the transformer. Using damping split inductor, significant regulation improvements could be achieved under light-load conditions with not any change in control strategy and almost zero hardware cost. In addition, based on impedance analysis of the resonant tank, the effects of the proposed method are analyzed including voltage gain, soft switching characteristics, suppression of high frequency interference components, and system power loss. Moreover, the detailed design process and optimization conditions of the damping split inductor parameters are carefully illustrated. Eventually, the experimental results demonstrate the characteristics mentioned above for the 96 W prototype at the expense of a maximum increase in device loss of 0.85 W. [ABSTRACT FROM AUTHOR]

Most fuel cell electric vehicles require wide voltage-gain DC–DC converters to increase and equalize the relatively low voltage of fuel cell stacks with DC link bus or energy-storage devices, such as supercapacitors or batteries. This paper proposes two new non-isolated DC–DC converters suitable for such applications, which can be extended to other electric vehicles as well. The proposed converters combine the main characteristics of both quadratic Boost and Ćuk converters, offering high step-up voltage and control simplicity using only one ground referenced active power switch. Additionally, the proposed topologies present reduced voltage stress across the active power switch when compared to other boost converters. Considerations about the design of the proposed converters will also be presented. Experimental results obtained using a laboratory prototype validate the effectiveness and feasibility of the proposed topologies and its suitability for fuel cell electric vehicles. [ABSTRACT FROM AUTHOR]

A new single-switch high step-up dc–dc converter is proposed, in this paper, for fuel cell vehicles. The proposed topology utilizes an L2C3D2 network to obtain high voltage gain and reduce the voltage stress on the power switch. Additionally, the proposed converter has a universal input voltage in order to suit the soft output characteristics of the fuel cell. Comprehensive analyses of the steady-state operation in continuous conduction mode and discontinuous conduction mode, and design considerations of the proposed converter are given. Finally, a 400 V/1.6 kW scaled-down prototype is developed to validate the effectiveness and feasibility of the proposed converter. [ABSTRACT FROM AUTHOR]

In order to use the dynamic low-voltage fuel cell stack in a fuel cell vehicle with a constant high voltage (400 V) dc bus, a capacitor-clamped H-type boost dc-dc converter with a wide voltage gain is proposed in this paper. In the input-voltage side, a capacitor clamped H-type structure is adopted to reduce input current ripple, avoid narrow-pulse of pulsewidth modulation voltage waveforms, and decrease the conduction loss of power switches; while in the output-voltage side, a switched-capacitor structure is adopted to achieve high voltage gain and decrease the voltage stress of all power semiconductors and capacitors. The operating principle, characteristic, control strategy, parameters design, and comparison with other converters are analyzed, and a 400 W prototype is developed. As a result, the converter can transform low-voltage from 25 V to 70 V in to 400 V with a wide voltage-gain range, which maximum efficiency is 94.72%. The experimental results also validate the aforementioned characteristics of the proposed converter and the correctness of theoretical analysis. This converter is suitable to serve as power interface for fuel cell vehicles. [ABSTRACT FROM AUTHOR]

A nonisolated single-stage on-board charger for electric vehicles has been proposed to increase system efficiency and power density in previous works. However, its ability to achieve high efficiency is limited by variations in the electric utility and battery, especially during the step-down operation. This paper proposes an advanced control algorithm that improves system efficiency in the step-down mode by controlling each switch asymmetrically using a phase-shift control. The proposed algorithm consists of only one controller, which prevents transient states from causing variations in the controller. The algorithm decreases the magnitude and ripple of the inductor current, which improves the charging efficiency by approximately 4.1% over at the 3.7-kW full load that of the conventional algorithm in the step-down mode, and measured total harmonic distortion and power factor are 3.2% and 0.995, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

Due to an increasing in-vehicle electric load demand, a new 48-V electric system architecture proposed by German premier car manufacturers has been gaining increasing attention recently for electrified vehicles. In this paper, a multiple-voltage bus converter for the 48-V and existing 12-V dual supply system, providing additional flexible dc bus voltages, is proposed. The proposed converter can provide a dual flexible dc voltage bus and an additional dependent voltage bus while simultaneously managing the 12-V supply net using only one single-leg switch pole and a diode. The additional dc voltage buses will provide more options to accommodate variable electric load components in a vehicle, improving their power density. Due to the multiple control objectives, the single-leg pole requires a multimode switching strategy to regulate the additional bus voltages. To improve the onboard vehicle system reliability and performance, an impedance network structure is implemented in the converter to obtain a dead-time-free pulsewidth modulation (PWM). Simulation and experimental results are presented to verify the feasibility and effectiveness of the proposed structure and control method. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

This paper presents the design guideline of a bidirectional isolated Ćuk converter with an active-snubber circuit, which is used as a cell level tester for multiple automotive dc energy storage devices (ESDs), such as ultracapacitors, Li-ion batteries, and NiMH batteries. The converter interfaces those automotive dc ESD cells with 24-V dc systems, and it realizes bidirectional power flow with two main switches. Based on the ratings of those dc ESD cells, the designed converter operates at a very low voltage range, i.e., from 1.5 to 6 V, with current as high as 300 A. The detailed operation principle and major features, such as soft switching and energy recovery, are analyzed under continuous current mode. Based on the analysis, the design guideline of the dc–dc converter is presented. A 1.2-kW laboratory prototype has been built and tested with full power rating. Both simulation and experimental results are presented to verify the analysis. [ABSTRACT FROM PUBLISHER]

This paper presents the design and control of a high-efficiency multiphase dc–dc converter for a truck auxiliary power unit (APU) fed by a fuel-cell stack. The power-stage design methodology and the operation of the designed power stage used to achieve high efficiency are described in detail. To operate the designed converter as a truck APU, the mode transfer control scheme, where smooth transitions of the voltage and current control modes are necessary, is proposed, and the current controller design procedure is described. A 5-kW four-phase dc–dc converter prototype is built with the proposed power-stage configuration, and the proposed control strategy is applied to control the dc–dc converter. The efficiency of the converter is more than 99.5% at near 10% load and above 98% from 10% to 100% load range. Simulations and experimental results are provided to verify the feasibilities of dc–dc converter operation and the proposed control strategy in the truck APU application. [ABSTRACT FROM PUBLISHER]

Plug-in hybrid electric vehicles (PHEVs) will play a vital role in future sustainable transportation systems due to their potential in terms of energy security, decreased environmental impact, improved fuel economy, and better performance. Moreover, new regulations have been established to improve the collective gas mileage, cut greenhouse gas emissions, and reduce dependence on foreign oil. This paper primarily focuses on two major thrust areas of PHEVs. First, it introduces a grid-friendly bidirectional alternating current/direct current ac/dc–dc/ac rectifier/inverter for facilitating vehicle-to-grid (V2G) integration of PHEVs. Second, it presents an integrated bidirectional noninverted buck–boost converter that interfaces the energy storage device of the PHEV to the dc link in both grid-connected and driving modes. The proposed bidirectional converter has minimal grid-level disruptions in terms of power factor and total harmonic distortion, with less switching noise. The integrated bidirectional dc/dc converter assists the grid interface converter to track the charge/discharge power of the PHEV battery. In addition, while driving, the dc/dc converter provides a regulated dc link voltage to the motor drive and captures the braking energy during regenerative braking. [ABSTRACT FROM PUBLISHER]

The cell voltage imbalance of series-connected energy storage cells, such as supercapacitors (SCs) and lithium-ion cells, causes premature deterioration and a decrease in the available energies of the cells. Various equalization techniques have been developed for diminishing such imbalances. However, since the number of switches, sensors, and/or multiwinding transformers present in conventional equalizers is directly proportional to the number of series connections of the cells, the circuit complexity and cost of the equalizers are prone to increase with the number of series connections. In this paper, single-switch cell voltage equalizers using multistacked buck-boost converters, such as the single-ended primary inductor converter (SEPIC), Zeta, and Ćuk converters, are proposed. These equalizers consist of passive components and a single switch, significantly reducing the complexity of the circuit when compared with that of conventional equalizers. In addition, when the proposed equalizers operate in discontinuous conduction mode, feedback control is not required to limit currents flowing through cells and circuit components. The proposed equalizers are compared with conventional topologies in terms of the number of active and passive components required. Operating analyses were conducted under both cell-voltage-balanced and -imbalanced conditions. Experimental equalization tests were performed for four series-connected SCs using the SEPIC-based single-switch equalizer. The energies of the series-connected SCs were preferentially redistributed by the equalizer to the cell(s) having the lowest voltage, resulting in the elimination of the cell voltage imbalance and subsequent uniformity of the cell voltages. [ABSTRACT FROM PUBLISHER]