Energy Efficiency Comparison of Hybrid Powertrain Systems for Fuel-Cell-Based Electric Vehicles

Fuel cell electric vehicles have great superiorities in endurance mileage, charging speed and climate tolerance compared to battery electric vehicles. However, a supercapacitor or battery bank is required to maintain a fast-dynamic response, which leads to several hybridization structures for fuel-cell-based electric vehicles due to the unique characteristics of each device, and their performances are also differing. The purpose of this paper is to provide a comprehensive comparison of hybrid powertrain systems for three types of powertrains: fuel cell/supercapacitor passive hybrid, fuel cell/supercapacitor semi-active hybrid, and fuel cell/battery semi-active hybrid. Each powertrain component model is developed from the real components wherever possible, and Honda FCX Clarity fuel cell vehicle is studied as the benchmark. The powertrain energy efficiency under Worldwide harmonized Light vehicles Test Cycle (WLTC) is analyzed and evaluated. The simulation results show that three powertrains have the same energy consumption, and fuel cell/supercapacitor passive hybrid powertrain increases the system efficiency by 2% and 4% in propulsion and regenerative braking, respectively. By contrast, the other two powertrain topologies have similar performance in terms of energy efficiency

Adaptive parameter identification of a fuel cell system for health-conscious energy management applications

Since a proton exchange membrane (PEM) fuel cell (FC) has time-varying characteristics, its online characteristics estimation (voltage, power, internal resistance, etc.) is becoming a key step in designing an energy management strategy (EMS) for hybrid FC vehicles. In this respect, this paper proposes a new method based on Lyapunov adaptation law to estimate the linear and nonlinear parameters of a renowned PEMFC model in the literature. Unlike most of similar estimators, the suggested approach determines the maximum current, which is a nonlinear parameter, online while guaranteeing the system closed-loop stability. This parameter is normally assumed to be constant while it changes through time owing to degradation and operating conditions variation. This alteration makes the model imprecise while extracting some important characteristics, such as maximum power and polarization curve. Therefore, it needs to be regularly updated along with other parameters. To demonstrate the capability of the suggested method, a detailed comparison is provided with the well-known extended Kalman filter (EKF) as an attested nonlinear estimator. Moreover, to highlight the effectiveness of the nonlinearity consideration, a comparison with KF is performed where the nonlinear parameter is considered constant. The performed experiments on a 500-W PEMFC show that the proposed method can be over twice as accurate as EKF and KF concerning the estimation of maximum power and current while its runtime is nearly half of them

Model Based Automotive System Integration: Fuel Cell Vehicle Hardware-In-The-Loop

abstract: Over the past decade, proton exchange membrane fuel cells have gained much momentum due to their environmental advantages and commutability over internal combustion engines. To carefully study the dynamic behavior of the fuel cells, a dynamic test stand to validate their performance is necessary. Much attention has been given to HiL (Hardware-in-loop) testing of the fuel cells, where the simulated FC model is replaced by a real hardware. This thesis presents an economical approach for closed loop HiL testing of PEM fuel cell. After evaluating the performance of the standalone fuel cell system, a fuel cell hybrid electric vehicle model was developed by incorporating a battery system. The FCHEV was tested with two different control strategies, viz. load following and thermostatic. The study was done to determine the dynamic behavior of the FC when exposed to real-world drive cycles. Different parameters associated with the efficiency of the fuel cell were monitored. An electronic DC load was used to draw current from the FC. The DC load was controlled in real time with a NI PXIe-1071 controller chassis incorporated with NI PXI-6722 and NI PXIe-6341 controllers. The closed loop feedback was obtained with the temperatures from two surface mount thermocouples on the FC. The temperature of these thermocouples follows the curve of the FC core temperature, which is measured with a thermocouple located inside the fuel cell system. This indicates successful implementation of the closed loop feedback. The results show that the FC was able to satisfy the required power when continuous shifting load was present, but there was a discrepancy between the power requirements at times of peak acceleration and also at constant loads when ran for a longer time. It has also been found that further research is required to fully understand the transient behavior of the fuel cell temperature distribution in relation to their use in automotive industry. In the experimental runs involving the FCHEV model with different control strategies, it was noticed that the fuel cell response to transient loads improved and the hydrogen consumption of the fuel cell drastically decreased.Dissertation/ThesisMasters Thesis Engineering 201