Performance comparison of input current ripple reduction methods in UPS applications with hybrid PEM fuel cell/supercapacitor power sources

An uninterruptible power supply (UPS) system with different input current ripple reduction methods is proposed, and a comparison research has been conducted about these methods. The proposed UPS system consists of a 63-cell 300 W proton exchange membrane (PEM) fuel cell stack, two 16-cell supercapacitors (SCs) in series, a high-efficiency push-pull DC/DC converter and a half-bridge DC/AC inverter. Besides that the traditional push-pull DC/DC converter has inherent advantages of low input-current stress and high voltage conversion ratio, the SCs, LC filter, and an active clamp circuit are employed to reduce the input current ripples in the UPS system. First, the input current ripple generation and performance without an external component are analyzed and modeled in the PEM fuel cell. Then the input current ripple reduction methods mentioned above are proposed and operated in the designed UPS system. Finally, the experimental results show that the input current ripple can be further reduced by using different current ripple reduction approaches, and the active compensation method has better performance than the passive compensation method. The input current ripple is less than 5% of the rated input current. © 2014 Elsevier Inc. All rights reserved

Input current ripple reduction and high efficiency for PEM fuel cell power conditioning system

© 2017 IEEE. To solve the issues of the open-loop control accuracy in a proton exchange membrane (PEM) fuel cell power conditioning system (PCS) with active clamp push-pull DC/DC converter for input current ripple reduction, a novel closed-loop digital-controlled method is proposed. The proposed PEM fuel cell PCS consists of a high-efficiency high-step-up current-fed resonant push-pull DC/DC converter and a half-bridge inverter. A fully digital-controlled strategy in the active-clamped circuit is employed to reduce the voltage spike and low frequency current ripple (LFCR) on the power switches for improving the lifespan of PEM fuel cell and raising the system reliability. By using the closed-loop current ripple reduction control, the LFCR is further reduced. A 300 W prototype is implemented and tested. Experimental results show that the minimum efficiency at full load is about 94.8% and the ripple current is less than 1.2% of the rated input current

A review on mitigation technologies of low frequency current ripple injected into fuel cell and a case study

© 2020 Hydrogen Energy Publications LLC This paper reviews the state-of-the-art of mitigation technologies of low frequency current ripple (LFCR) injected into fuel cell (FC). Although there are their own merits and demerits, the optimized LFCR control techniques and topology structures are characterized in many aspects like performance, durability, reliability and lifetime of FC. Three mains topologies and mitigation methods of LFCR have been investigated based on the literature review, which are the passive compensation methods, active compensation methods, and passive and active hybrid compensation methods. Some rules based tables are set to evaluate the LFCR against the topologies, control strategies, current ripple, application and advantages/limitations. Moreover, the mitigation control strategies are compared side by side with their specific applications in FC system. To select and implement them, this review can provide a reference and basis for the researchers in related fields. Finally, a case study in an uninterruptible power supply application is conducted

Three-Phase Isolated Boost DC-DC Converter for High Voltage Applications

The voltage fed DC-DC converter has been suffering from problems associated with large transformer leakage inductance due to high transformer turn ratio when it is applied to low-voltage, high-current step-up application such as fuel cells. This paper proposes a new three-phase voltage fed DC-DC converter, which is suitable for high-voltage, high-current applications. The transformer turn ratio is reduced to half owing to ?-Y connection. The zero-voltage and zero-current switches (ZVZCS) for all switches are achieved over wide load range without affecting effective duty cycle. A clamp circuit not only clamps the surge voltage but also reduces the circulation current flowing in the high-current side, resulting in significantly reduced conduction losses. The duty cycle loss can also be compensated by operation of the clamp switch.The detailed design and operating principles are described and simulated using Pspice. The proposed converter is very attractive for electrolyser application.Keywords: High power DC–DC converter, three-phase DC-DC converter, active clamp circuit, Isolation transformer

Soft-switching current-fed power converters for low voltage high current applications

Ph.DDOCTOR OF PHILOSOPH

A Comprehensive Review of DC-DC Converters for EV Applications

DC-DC converters in Electric vehicles (EVs) have the role of interfacing power sources to the DC-link and the DC-link to the required voltage levels for usage of different systems in EVs like DC drive, electric traction, entertainment, safety and etc. Improvement of gain and performance in these converters has a huge impact on the overall performance and future of EVs. So, different configurations have been suggested by many researches. In this paper, bidirectional DC-DC converters (BDCs) are divided into four categories as isolated-soft, isolated-hard, non-isolated-soft and non-isolated-hard depending on the isolation and type of switching. Moreover, the control strategies, comparative factors, selection for a specific application and recent trends are reviewed completely. As a matter of fact, over than 200 papers have been categorized and considered to help the researchers who work on BDCs for EV application

Power Decoupling Control for Single-Phase Grid-Tied PEMFC Systems With Virtual-Vector-Based MPC

The fuel cell grid-tied power generation system usually includes a dc-dc converter and a dc-ac inverter. In a single-phase system, inherent low-order current pulsations are introduced into the system, which can have harmful effects on the fuel cell stack. For example, reducing the output voltage and output efficiency, a reduction in service life, and even accelerates the degradation rate of the membrane electrode of a proton exchange membrane fuel cell (PEMFC). In addition, dc/ac coupling power can cause distortion in the dc input current and ac grid current. To eliminate the input ripple and ensure high ac power quality on the grid side, this paper proposes a novel power decoupling control for single-phase grid-tied PEMFC systems, which uses an improved model predictive control (MPC) algorithm. With the help of the virtual vector methods, which are realized by a two-stage optimization method, excellent tracking effect and robustness can be ensured. Simulations and experimental results show that the proposed algorithm can not only completely eliminate the input current ripple and reduce the total harmonic distortion (THD) of ac current on the grid side, but also improve the transient performance of the system

Comprehensive influences measurement and analysis of power converter low frequency current ripple on PEM fuel cell

© 2019 Hydrogen Energy Publications LLC To deeply understand the influences of power converter's low frequency current ripple (LFCR) and harmonics on a proton exchange membrane fuel cell (PEMFC) in its power conditioning system (PCS), a comprehensive measurement and analysis of the influences of LFCR and harmonics on PEMFC's performance and durability is investigated in this paper. Based on an equivalent circuit model of PEMFC stack and a mechanism model for evaluating the LFCR effects on the PEMFC, this paper studies primarily and systematically the comprehensive influences of LFCR and harmonics on PEMFC performances and durability, such as (1) degrading the PEMFC performance, (2) shortening the lifetime of PEMFC, (3) reducing the stack output power, (4) lowing its availability efficiency, (5) producing more heat and raising the PEMFC temperature, (6) consuming more fuel, and (7) decreasing the fuel utilization. Finally, a Horizon 300 W PEMFC stack is implemented and tested