The issue of renewable energy is becoming significant due to increasing power demand, instability of the rising oil prices and environmental problems. Among the various renewable energy sources, fuel cell is gaining more popularity due to their higher efficiency, cleanliness and cost-effective supply of power demanded by the consumers. This paper presents a comprehensive review of different fuel cell technologies with their working principle, advantages, disadvantages and suitability of applications for residential/grid-connected system, transportation, industries and commercial applications. Development of mathematical model of fuel cell required for simulation study is discussed. This paper also focuses on the necessity of a suitable power-conditioning unit required to interface the fuel cell system with standalone/grid applications.

A review on fuel cell technologies and power electronic interface

PEM fuel cell system control: A review

This paper proposes a boost converter with coupled inductors and a buck-boost type of active clamp. In the converter, the active-clamp circuit is used to eliminate the voltage spike that is induced by the trapped energy in the leakage inductor of the coupled inductors. The active switch in the converter can still sustain a proper duty ratio even under high step-up applications, reducing voltage and current stresses significantly. Moreover, since both main and auxiliary switches can be turned on with zero-voltage switching, switching loss can be reduced, and conversion efficiency therefore can be improved significantly. A 200 W prototype of the proposed boost converter was built, from which experiment results have shown that efficiency can reach as high as 92% and surge can be suppressed effectively. It is relatively feasible for low-input-voltage applications, such as fuel cell and battery power conversion.

Boost Converter With Coupled Inductors and Buck–Boost Type of Active Clamp

This paper presents the current research trends and future issues for industrial electronics related to transportation electrification. Specific emphasis is placed on electric and plug-in hybrid electric vehicles (EVs/PHEVs) and their critical drivetrain components. The paper deals with industry related EV energy storage system issues, EV charging issues, as well as power electronics and traction motor drives issues. The importance of battery cell voltage equalization for series-connected lithium-ion (Li-ion) batteries for extended life time is presented. Furthermore, a comprehensive overview of EV/PHEV battery charger classification, standards, and requirements is presented. Several conventional EV/PHEV front-end ac/dc charger converter topologies as well as isolated DC/DC topologies are reviewed. Finally, this paper reviews various EV propulsion system architectures and efficient bidirectional DC/DC converter topologies. Novel DC/AC inverter modulation techniques for EVs are also presented. The architectures are based on the battery voltage, capacity, and driving range.

Industrial Electronics for Electric Transportation: Current State-of-the-Art and Future Challenges

A new design approach achieving very high conversion efficiency in low-voltage high-power isolated boost dc-dc converters is presented. The transformer eddy-current and proximity effects are analyzed, demonstrating that an extensive interleaving of primary and secondary windings is needed to avoid high winding losses. The analysis of transformer leakage inductance reveals that extremely low leakage inductance can be achieved, allowing stored energy to be dissipated. Power MOSFETs fully rated for repetitive avalanches allow primary-side voltage clamp circuits to be eliminated. The oversizing of the primary-switch voltage rating can thus be avoided, significantly reducing switch-conduction losses. Finally, silicon carbide rectifying diodes allow fast diode turn-off, further reducing losses. Detailed test results from a 1.5-kW full-bridge boost dc-dc converter verify the theoretical analysis and demonstrate very high conversion efficiency. The efficiency at minimum input voltage and maximum power is 96.8%. The maximum efficiency of the proposed converter is 98%.

High-Efficiency Isolated Boost DC–DC Converter for High-Power Low-Voltage Fuel-Cell Applications

In this paper, a new active clamping current-fed half-bridge converter is proposed, which is suitable for fuel cell power generation systems. The proposed converter is superior to conventional dc-dc converters in terms of efficiency and component utilization. The overall efficiency is estimated to be 94% at full load.

Fuel Cell Generation System With a New Active Clamping Current-Fed Half-Bridge Converter

Fuel cell (FC) has slow response characteristic for load variation. In this paper, bi-directional dc-dc converter for FC generation system is proposed to improve load response characteristic. The bi-directional converter interfaces the low voltage battery to the inverter dc link of FC generation system. When power flows from the low voltage side (battery: 48 V) to the high voltage side (dc link: 380 V), the circuit works in discharge operation (boost mode) to power the high voltage side load; otherwise, it works in charge operation (buck mode) to charge the low voltage side battery. A simple voltage clamp branch is used to limit transient voltage across the current-fed full bridge and realize zero-voltage-switching (ZVS) during discharge operation. A soft switched, isolated bi-directional dc-dc converter has been developed for FC generation system, in which the 48 V battery for the system accessory loads is also used to start up the FCs and to charge the energy consumed on operating of FC generation system.

Bi-directional dc-dc converter for fuel cell generation system

In this paper, a new active clamping current-fed half-bridge converter has been proposed, which is suitable for fuel cell based power generation systems. The proposed converter has outstanding advantages over the conventional dc-dc converters with respect to high efficiency, high power density, and high component utilization. In special, the proposed converter has predominant high boosting output voltage and high efficiency characteristics under the inherently severe low output voltage of the fuel cell through the overall load conditions. Moreover, the developed converter has been experimentally tested with the help of a fuel cell simulator, which is developed by Sungkyunkwan Univ. and can generate the V-I characteristics of polymer electrolyte membrane fuel cell (PEMFC), so that the performance of the proposed converter could be effectively examined and the validity of the converter could be verified.

An active clamping current-fed half-bridge converter for fuel-cell generation systems

Fuel cell system includes a fuel processor and subsystems Io manage air, water, thermal energy, and power. The overall system is high-priced and needs to peripheral devices. In this paper, the fuel cell simulator designed and manufactured as electrical characteristic of fuel cell generation system uses a simple buck converter to overcome these disadvantages. Characteristic of voltage and current (V-I) curve for fuel evil simulator is controlled by the linear function of being simplified, and we designed the fuel cell simulator. In addition, to verify fuel cell generation system performance and operation, full-bridge DC/DC converter and single-phase DC/AC inverter are designed and manufactured for fuel cell applications. The close agreement between the simulation and the experimental results confirms the validity and usefulness of the proposed fuel cell simulator.

A 3 kW fuel cell generation system using the fuel cell simulator

A high efficiency active clamp sepic-flyback converter is presented. The proposed converter is superposition of sepic converter mode and flyback converter mode. Not only sepic mode output but also flyback mode output can be fully regulated by constant frequency PWM control. Merging sepic and flyback topology can share the transformer, power MOSFET, and active clamp circuit. It has outstanding advantages over the conventional dc-dc converters with respect to high efficiency, high power density, and component utilization. The operation principle of the proposed converter is described and verified by simulation and experimental result

Su-Jin Jang

Papers

Fuel Cell Generation System With a New Active Clamping Current-Fed Half-Bridge Converter

Bi-directional dc-dc converter for fuel cell generation system

An active clamping current-fed half-bridge converter for fuel-cell generation systems

A 3 kW fuel cell generation system using the fuel cell simulator

The Active Clamp Sepic- Flyback Converter