Jianfeng Hua

Control strategy optimization of a hybrid fuel cell vehicle with braking energy regeneration

This paper deals with the optimized control strategy within the vehicle which is driven by a fuel cell stack hybrid with a NiMH battery. The aim is the instantaneous energy management to optimize the hydrogen consumption. At first the powertrain was modeled using data on testbed. Then the optimization control problem basing on an equivalent hydrogen consumption strategy is defined, where the motor target torque and DC/DC target current should be calculated. According to the shift signals and pedal position signals, the vehicle operation can be divided into two modes, non-brake mode (idle, drive backward, drive forward, slide) and brake mode. The optimization problem was solved respectively. Results in ldquoChina typical city bus cyclerdquo testing show the robustness and effectiveness of the strategy in improving fuel economy while maintaining drivability. The fuel economy was improved from 9.6 kg/100 km to 7.9 kg/100 km and the battery SOC was kept around 47%.

Modeling and Experimental Study of PEM Fuel Cell Transient Response for Automotive Applications

Abstract This paper presents an analysis of the dynamic response of a low pressure proton exchange membrane (PEM) fuel cell stack to step changes in load, which are characteristic of automotive fuel cell system applications. The goal is a better understanding of the electrical and electrochemical processes when accounting for the characteristic cell voltage response during transients. The analysis and experiment are based on a low pressure 5 kW proton exchange membrane fuel cell (PEMFC) stack, which is similar to those used in several of Tsinghuas fuel cell buses. The experimental results provide an effective improvement reference for the power train control scheme of the fuel cell buses in Olympic demonstration in Beijing 2008.

A comparative study of equivalent circuit models and enhanced equivalent circuit models of lithium-ion batteries with different model structures

Lithium-ion battery model is critical for voltage and state of charge (SOC) determination, and the equivalent circuit model (ECM) is frequently implemented in real -time cases due to low complexity, but the low-SOC-area performance requires improvement. This paper introduces an enhanced equivalent circuit model (EECM) based on electrochemical analysis, in which the surface SOC (SOCsurf) reflects the lithium concentration at the particle surface and is used to determine the terminal voltage. Five empirical based models with different model structures (in which two ECMs and three EECMs included) are selected to compare the model accuracy and complexity. Experiments were carried out on a battery test system with a temperature chamber, and a modified hybrid pulse power characterization (HPPC) profile was employed to measure the battery dynamic response. The genetic algorithm method is implemented in model parameterization, and the voltage estimation accuracy of the five empirical models is compared in SOC range 0~100%. The results show that the EECMs considering SOCsurf provides better accuracy than the traditional ECMs in low-SOC area, and the EECM with one RC component and one DS component provides the optimum performance considering accuracy and complexity.

Control algorithm of fuel cell/battery hybrid vehicular power system

In this paper, a control strategy for a vehicular power system combined with a proton exchange membrane fuel cell and a battery energy system (BES) has been presented. The control, witch takes into account the slow dynamic of fuel cell and the state of charge (SOC) of BES, is investigated based on the proposed fuzzy logic control (FLC) for the vehicular power system. Fuel cell output power was determined according to the driving load requirement and the SOC, using fuzzy dynamic decision-making and fuzzy self-organizing concepts. Analysis of simulation results is discussed by Matlab/Simulink software to verify the effectiveness of the proposed control strategy. The control scheme can be used to improve the operational efficiency of hybrid power system.

MEMS and J2ME based acceleration real-time measurement and monitoring system for fuel cell city bus

Since Jul. 2008, Beijing started a clean public transportation plan for the 29th Olympic Games. As a part of this plan, three fuel cell buses will work in a fixed bus line for one year as green energy vehicle demonstration for public. This is the first time to demonstrate homemade fuel cell buses in Beijing. The buses really serve as an ordinary bus on the streets of Beijing. Some control strategies are not adequately mature yet during the complex transient city cycle and are still needed to be optimized with the updating experiment data collected with day-to-day operation. Due to the speciality of fuel cell engine and electrified power-train system, some particular measurement, monitoring and calibration devices are ensuring normal operation of the fuel cell bus in the demonstration. The 3-axial accelerations of the fuel cell buses are the significant parameters to evaluate dynamical performance and manipulation stability. Furthermore they also feature the characteristic of city cycle route in demonstration. In order to measure and monitor the 3-axial accelerations of the fuel cell bus rapidly and conveniently, a novel wireless portable online monitoring system based on Java 2nd Micro Edition (J2ME) and Micro-Electro Mechanical Systems (MEMS) technology is implemented. The monitoring terminal could be a cell phone, PDA or any other smart mobile device with Bluetooth interface. The data exchange between monitoring terminals and VCU (Vehicle Control Unit) is highly secure under the guarantee of the Bluetooth pairing and authentication mechanism.

Application and study of novel electronic technologies on vehicle control system of fuel cell bus

Under the background of the increasingly serious global energy crisis and environmental problems, governments and enterprises around the world have paid more attention to the development of a new generation of sustainable energy. The fuel cell bus has become an ideal choice for new energy vehicles due to its zero emission, high efficiency as well as long endurance. A fuel cell bus consists of various components, such as fuel cell stacks, power batteries, DC/DC converter, electronic motor and etc. A distributed control system is developed for the fuel cell bus which has been facing many challenges from complex electromagnetic environment, demands of on-line monitoring and diagnosis, wide working temperature range, energy dynamic optimization (EDO) ability and etc.