Fuel Cell City Bus Research Articles

Finite Element Analysis and Optimization of Hydrogen Fuel Cell City Bus Body Frame Structure

Hydrogen fuel cell city bus is a type of new energy public transportation. In this paper, in order to evaluate the safety performance of a newly developed hydrogen fuel cell city bus body frame designed by the collaborating enterprise, finite element analysis is conducted to investigate its structural mechanics and dynamic characteristics under four typical operating conditions, including horizontal bending, ultimate torsion, emergency cornering, and emergency braking. Based on the simulation results, although the body frame of the bus meets the stiffness design requirements and avoids body resonance, it exhibits maximum stresses of 328.9 MPa and 348.6 MPa under emergency cornering and ultimate torsion conditions, respectively, exceeding the material yield strength and failing to satisfy the strength design requirements. Therefore, the size optimization method is employed to optimize the thickness of the body frame components. After optimization, the maximum stresses are reduced to 262.7 MPa and 300.6 MPa, respectively, representing a reduction of up to 20.13%. The optimization significantly improves performance and meets the strength design requirements. Furthermore, the body frame is lightened by 106 kg, achieving the goal of weight reduction.

Half-Power Prediction and Its Application on the Energy Management Strategy for Fuel Cell City Bus

The fuel cell hybrid powertrain is a potential power supply system for fuel cell vehicles. The underlying problem is that the fuel cell vehicles encounter exhaustive hydrogen consumption. To effectively manage hydrogen consumption, the aim is to propose fuel cell city bus power and control system. The underlying idea is to determine the target power of fuel cell through simulation study on fuel cell and battery energy management strategy and road test verifications. A half-power prediction energy management strategy is implemented to predict the target power of the fuel cell in the current time step based on the demand power of the vehicle and the state of charge (SOC) of the battery in the previous time steps. This offers better understanding of the correlation between fuel cell power and vehicle drive cycle for enabling effective power supply management. The research results show that the half-power prediction energy management strategy effectively reduces the hydrogen consumption of the vehicle by 7.1% and the number of battery cycle by 6.0%, compared to the stepped management strategy of battery SOC. When applied to a 12-m fuel cell city bus—F12, specially designed and manufactured for the Winter Olympic Games in 2022—the fuel economy of 3.7 kg/100 km is achieved in urban road conditions. This study lays a foundation for providing the powertrain configuration and energy management strategy of fuel cell city bus.

An Energy Management Strategy and Parameter Optimization of Fuel Cell Electric Vehicles

This study involved a detailed analysis of an energy distribution strategy and the parameters of key components of fuel cell electric vehicles (FCEVs). In order to better utilize the advantages of multiple energy sources, the wavelet-fuzzy energy management method was used to adjust the demand power allocation among multiple energy sources, and particle swarm optimization (PSO) was used to solve highly nonlinear optimization problems under multi-dimensional and multi-condition constraints. The multi-objective optimization problem of predefined driving cycle powertrain parameters about fuel economy and system durability was studied. The parameters of the key components of the system were optimized, including the size parameters of the air com-pressor and the number of batteries and ultra-capacitors. Furthermore, the driving state under specific working conditions was analyzed, and a nonlinear model with system durability and fuel economy as the optimization objectives were established, which greatly reduced the costs, reduced the fuel consumption rate and extended the battery life. The simulation results showed that for a UDDS cycle, the FCS’s maximal net output power of 83 kW was optimal for the fuel economy and system durability of a fuel cell city bus.

Prediction of voltage degradation trend for a proton exchange membrane fuel cell city bus on roads

Prognostics and Health Management (PHM) is among the most significant and effective technologies to improve the durability of a proton exchange membrane (PEM) fuel cell system. This paper deals with the prediction issues of the degradation trend for PEM fuel cells equipped in a city bus. First, three aging parameters are extracted from a multi-parameter voltage model, and two of them are selected to represent the degradation of electronic and ionic resistance separately for the first time. Then the parameters are initialized by harmony search (HS) algorithm with an improved objective function, and updated by resorting to the particle filtering (PF) algorithm. Subsequently, Bayesian ridge regression (BRR) and Gaussian progress regression (GPR) are utilized to establish the relationship between the operating time and aging parameters. We categorized the input of the regression models into two classes: the total operating time and the cumulative time of four operating conditions. The results indicate that the latter performs better than the former in characterizing the future trend of aging parameters. Moreover, it is observed that BRR is more attractive since its computational time is far less than that of GPR while the mean absolute error (MAE) is no more than 8.5 mV. • Electronic and ionic resistances are studied separately in the voltage model. • A penalty coefficient is deployed in the objective function of HS algorithm. • The prognosis method can predict the degradation of PEMFC integrated to a city bus.

Study on the Influence of the Center of Gravity of Fuel Cell City Bus on its Handling Characteristics

The vehicles driven by combustion engine leads to environmental problems because of fossil fuel consumption. In recent years, many policies have adopted to support the development of new energy vehicles, especially battery electric vehicles as the main strategy in China. For the battery electric vehicles, the position of the battery pack can change the centroid position of the vehicle because of its big mass, and it can also change the loading of each tire in the motion, which has important influence on the vehicle handing and stability performance. This article studies the relationship between handling characteristic and the change of centroid position on a fuel cell city bus, and then solves the suitable centroid position of this vehicle which makes the vehicle have satisfied steering characteristic.

Optimum of Fuel Cell City Bus Power Train

Fuel cell power system have many advantages on the principle of energy conversion compare with the internal combustion engine. It is essential to optimum the fuel cell power system. In this paper, three different solutions of fuel cell city bus power system were analyzed and simulated with MATLAB. The power performance and fuel economy of the three different layouts were calculated and put forward the best design.

Optimum of Fuel Cell City Bus Power Train

Optimum of Fuel Cell City Bus Power Train

Multi-objective energy management optimization and parameter sizing for proton exchange membrane hybrid fuel cell vehicles

The powertrain system of a typical proton electrolyte membrane hybrid fuel cell vehicle contains a lithium battery package and a fuel cell stack. A multi-objective optimization for this powertrain system of a passenger car, taking account of fuel economy and system durability, is discussed in this paper. Based on an analysis of the optimum results obtained by dynamic programming, a soft-run strategy was proposed for real-time and multi-objective control algorithm design. The soft-run strategy was optimized by taking lithium battery size into consideration, and implemented using two real-time algorithms. When compared with the optimized dynamic programming results, the power demand-based control method proved more suitable for powertrain systems equipped with larger capacity batteries, while the state of charge based control method proved superior in other cases. On this basis, the life cycle cost was optimized by considering both lithium battery size and equivalent hydrogen consumption. The battery capacity selection proved more flexible, when powertrain systems are equipped with larger capacity batteries. Finally, the algorithm has been validated in a fuel cell city bus. It gets a good balance of fuel economy and system durability in a three months demonstration operation.

Fuel cell system degradation analysis of a Chinese plug-in hybrid fuel cell city bus

Fuel cell hybrid electric vehicles are attracting increasing attention and research. However, the durability of fuel cell systems (FCS) is the main bottleneck in commercial application. A plug-in fuel cell city bus was developed by our group, and it completed several months of demonstration operation. A two-stage flowchart was proposed to clarify the FCS degradation analysis. The average cell voltage decline rate is approximately 346 μV/h at a current density of 120 A, under which the initial voltage is about 0.7 V. The estimated lifetime in the third stage reaches the design target. The final electrochemically active surface areas are approximately 80% of the initial value. A detailed degradation analysis of fuel cell voltage uniformity is presented, and a five-region degradation otherness analysis is proposed for performance uniformity analysis. The difference of equivalent resistance has been verified to be the main factor in degradation otherness of the regions and in system performance degradation.

Development of a PEM Fuel Cell City Bus with a Hierarchical Control System

The polymer electrolyte membrane (PEM) fuel cell system is considered to be an ideal alternative for the internal combustion engine, especially when used on a city bus. Hybrid buses with fuel cell systems and energy storage systems are now undergoing transit service demonstrations worldwide. A hybrid PEM fuel cell city bus with a hierarchical control system is studied in this paper. Firstly, the powertrain and hierarchical control structure is introduced. Secondly, the vehicle control strategy including start-stop strategy, energy management strategy, and fuel cell control strategy, including the hydrogen system and air system control strategies, are described in detail. Finally, the performance of the fuel cell was analyzed based on road test data. Results showed that the different subsystems were well-coordinated. Each component functioned in concert in order to ensure that both safety and speed requirements were satisfied. The output current of the fuel cell system changed slowly and the output voltage was limited to a certain range, thereby enhancing durability of the fuel cell. Furthermore, the economic performance was optimized by avoiding low load conditions.

Energy flow modeling and real-time control design basing on mean values for maximizing driving mileage of a fuel cell bus

This paper proposes an energy flow model and an optimal energy management strategy based on mean values for maximizing driving mileage of a fuel cell bus (FCB), which is powered by a polymer electrolyte membrane (PEM) fuel cell system and a lithium battery. Firstly, an energy flow model describing the relations between vehicle performance and power flow parameters is quantitatively established. An optimization problem for maximizing driving mileage on a predetermined route is defined, and an analytical solution with clear physical meanings is derived. Next, a practical real-time supervisory Energy Management strategy basing on Mean Values (EMMV) is proposed. The strategy, which doesn't require a priori knowledge of the driving trip, is then compared with several well-known strategies, e.g. charge depleting and charge-sustaining (CDCS), Blended, dynamic programming (DP), and Pontryagin's Minimum Principle (PMP). Simulation results show that, the proposed strategy achieves a near-optimal effect, and converges after one driving cycle on a predetermined bus route. Finally, on-road testing is carried out. The proposed strategy achieves an average endurance mileage on a real bus route of 162 km with a usable battery state of charge (SOC) of 90% and 20 kg hydrogen gas for a fully loaded fuel cell city bus.

Multi-objective component sizing based on optimal energy management strategy of fuel cell electric vehicles

A typical topology of a proton electrolyte membrane (PEM) fuel cell electric vehicle contains at least two power sources, a fuel cell system (FCS) and a lithium battery package. The FCS provides stationary power, and the battery delivers dynamic power. In this paper, we report on the multi-objective optimization problem of powertrain parameters for a pre-defined driving cycle regarding fuel economy and system durability. We introduce the dynamic model for the FCEV. We take into consideration equations not only for fuel economy but also for system durability. In addition, we define a multi-objective optimization problem, and find a quasi-optimal solution using a two-loop framework. In the inside loop, for each group of powertrain parameters, a global optimal energy management strategy based on dynamic programming (DP) is exploited. We optimize coefficients for the DP algorithm to reduce calculating time as well as to maintain accuracy. For the outside loop, we compare the results of all the groups with each other, and choose the Pareto optimal solution based on a compromise of fuel economy and system durability. Simulation results show that for a “China city bus typical cycle,” a battery capacity of 150Ah and an FCS maximal net output power of 40kW are optimal for the fuel economy and system durability of a fuel cell city bus.

The Optimal Design of Fuel Cell Bus Power Train

The transmission ratio of the fuel cell city bus should meet the requirement of economy and power performance. The transmission ratio and the main decelerator are the key factors to the economy and power performance of the bus. The special operating characteristic curve of motor is a basis to analyze the vehicle`s power and economy performance. Combined with the planned and the provided transmission ratio, the optimal gear ratio of the transmission can be calculated. So the vehicle`s economy and power performance are finally improved.

Application of Pontryagin's Minimal Principle to the energy management strategy of plugin fuel cell electric vehicles

This paper proposes an optimal real-time energy management strategy based on the Pontryagin's Minimal Principle (PMP) targeting at minimizing operation cost for a plug in proton electrolyte membrane (PEM) fuel cell city bus. The Dynamic Programming (DP) and PMP strategies are firstly deduced. Influences of the initial co-state value on the PMP strategy are analyzed. The DP, PMP, Charge Depleting Charge Sustaining (CDCS) and Blended strategies are compared in a simulation model. Results show that, major factors that influent the operation cost are the end value of battery State of Charge (SoC), the SoC trajectory curve, and the distribution of the working points of the fuel cell system. From a statistic viewpoint, the operation cost increases almost linearly with the end value of the SoC with a gradient of 1.41 Yuan.%−1. Compared with a CDCS strategy, the operation cost can be reduced by 7.2% through taking the DP strategy, and by 5.9% through taking the PMP strategy. The PMP strategy leads to an operation cost that is 1.4% higher than the DP, but it is applicable in the real-time control system. An online energy management strategy based on PMP was set up and applied to an embedded controller. Tests in the 30 “China city bus typical cycles” showed that, the fuel economy was 5.8 kg (100 km)−1, and the operation cost was 271.3 Yuan (100 km)−1.

Optimal sizing of plug-in fuel cell electric vehicles using models of vehicle performance and system cost

This paper presents an optimal sizing method for plug-in proton exchange membrane (PEM) fuel cell and lithium-ion battery (LIB) powered city buses. We propose a theoretical model describing the relationship between components’ parameters and vehicle performance. Analysis results show that within the working range of the electric motor, the maximal velocity and driving distance are influenced linearly by the parameters of the components, e.g. fuel cell efficiency, fuel cell output power, stored hydrogen mass, vehicle auxiliary power, battery capacity, and battery average resistance. Moreover, accelerating time is also linearly dependant on the abovementioned parameters, except of those of the battery. Next, we attempt to minimize fixed and operating costs by introducing an optimal sizing problem that uses as constraints the requirements on vehicle performance. By solving this problem, we attain several optimal sizing rules. Finally, we use these rules to design a plug-in PEM fuel cell city bus and present performance results obtained by on-road testing.

Real time optimal energy management strategy targeting at minimizing daily operation cost for a plug-in fuel cell city bus

This paper proposes an optimal real-time energy management strategy targeting at daily operation optimization for a plug in proton exchange membrane fuel cell electric vehicle (PFCEV) for public transportations. A novel real-time optimal energy management strategy based on the determined dynamic programming (DDP) strategy is proposed, namely the DBSD (charge Depleting – Blended – Sustaining – Depleting) strategy. A simulation model is set up to compare the DDP strategy, the DBSD strategy and the CDCS (Charge Depleting and Charge Sustaining) strategies. Compared to the CDCS strategy, the daily operating cost can be reduced by 6.4% with the DBSD strategy, and it can be reduced by 9.5% with the DDP strategy. On-road testing with the DBSD strategy shows that, the daily operation cost is 510.2 Sig. $ (100 km)−1. The electric energy consumption in pure battery driven mode is about 1.68 kWh km−1, and the equivalent hydrogen consumption in hybrid driven mode is about 0.14 kg km−1.

Hierarchical control of vehicular fuel cell / battery hybrid powertrain

In a proton exchange membrane (PEM) fuel cell/battery hybrid vehicle, a fuel cell system fulfills the stationary power demand, and a traction battery provides the accelerating power and recycles braking energy. The entire system is coordinated by a distributed control system, incorporating three key strategies: 1) vehicle control, 2) fuel cell control and 3) battery management. They make up a hierarchical control system. This paper introduces a hierarchical control strategy for a fuel cell / battery hybrid powertrain applied in a city bus. The vehicle control strategy comprises three parts: an energy management strategy, a brake regeneration strategy and an active tolerant control strategy. The entire powertrain power is split between the fuel cell system and the battery in such a way that the fuel cell system works in a quasi-steady state and the battery can keep charge sustaining. The braking energy is recycled on the basis of the pedal position and the rotational speed of the electric motor. An active tolerance control strategy is developed to guarantee the work of the entire system in case of malfunctions. A fuel cell system consists of a water and heat management system, an air system, a humidifier system and a hydrogen in-out let system. Control strategies are designed to regulate air supply and water cooling temperature. Primary tasks of a battery management system are to estimate the state of charge (SOC), and to keep the temperature in safety range. A real-time applicable strategy for SOC is developed. The temperature of the battery is controlled by some air fans with on-off strategy. The hierarchical control system was applied on a fuel cell city bus. Experimental results show the effectiveness of the proposed strategy.

Application and Study of Novel Software Technology on Vehicle Control System of Fuel Cell City Bus

The fuel cell city bus has become a favorite choice for new energy vehicle due to its free of emission,high energy conversion efficiency as well as long driving endurance.A fuel cell city bus consists of varied components,including fuel cell stack,power battery,DC/DC converter and electronic motor etc.A complex distributed control system is implemented for the fuel cell bus which has been facing the challenge of mass data transmission,complex control task,high quality real-time operation,system monitoring,in-system self programming and etc.The integrated application and implementation of a series of novel software technology in the control system development of the fuel cell city bus are presented in order to meet the requirements of the challenges,including OSEK/VDX RTOS,hardware-in-the-loop real-time simulation,time trigger controller area networks and seamless automatic code generation.These new technologies promote the development efficiency of the fuel cell control system,reduce system fault rate dramatically,and provide an open technology platform for fuel cell city bus control strategy optimization.

Bluetooth wireless monitoring, diagnosis and calibration interface for control system of fuel cell bus in Olympic demonstration

With the worldwide deterioration of the natural environment and the fossil fuel crisis, the possible commercialization of fuel cell vehicles has become a hot topic. In July 2008, Beijing started a clean public transportation plan for the 29th Olympic games. Three fuel cell city buses and 497 other low-emission vehicles are now serving the Olympic core area and Beijing urban areas. The fuel cell buses will operate along a fixed bus line for 1 year as a public demonstration of green energy vehicles. Due to the specialized nature of fuel cell engines and electrified power-train systems, measurement, monitoring and calibration devices are indispensable. Based on the latest Bluetooth wireless technology, a novel Bluetooth universal data interface was developed for the control system of the fuel cell city bus. On this platform, a series of wireless portable control auxiliary systems have been implemented, including wireless calibration, a monitoring system and an in-system programming platform, all of which are ensuring normal operation of the fuel cell buses used in the demonstration.

Adaptive Control of the Hybrid Power System in Fuel Cell City Bus

AbstractFor hybrid power system composed of a fuel cell engine and a group of Ni-H batteries, a new control method with a bi-directional power converter is proposed. On the base of analyzing the output characteristic of the fuel cell engine, an external characteristic of the bi-directional power converter is designed, making the Ni-H batteries automatically adjust their charging or discharging currents. As a result, the output power of the hybrid system is controlled adaptively, obtaining stable outputs of I-t and U-t processes of the power system.