Fuel Cell Electric Vehicles: Method for Characterization of Onboard Power Management System and Defining Vehicle Level Attributes

Fuel Cell and Battery Pack/Capacitors are two power sources on-board a Fuel Cell Electric Vehicle. Each having it's own set of boundary conditions and ideal operating conditions in order to deliver expected performance over the intended useful life. Such a dual power source architecture poses a challenge of optimally balancing power delivery from Fuel Cell and Battery Pack/Capacitor in order to ensure health of both these important aggregates of vehicle over it's intended useful life. Therefore, a method and tool for characterizing the Power Management System of Fuel Cell Electric Vehicle is required during development and validation. "Aggregate Sizing" and "Calibration of Power Control Strategy" are significant factors for optimum life of Fuel Cell powered vehicle without compromising performance. Although the former is mainly a design decision, the latter is crucial during testing and validation to achieve the design objective and avoid unwanted failures. Distribution of load catered by each supply units are compared with target distribution profile based on the design considerations like component sizing and warranty life, etc. In this proposed method, power spectral analysis is used to study/compare the distribution of transient loads between Fuel Cell and Battery Pack, as demanded by the vehicle operation over a real world application drive cycle. Spectral comparison of these 2 power signals with respect to the design intended profile can indicate, whether power split between Fuel Cell and Battery Pack is optimal or not? In case of sub-optimal split, vehicle calibration is retuned by adjusting the defined attributes through necessary calibration changes, which directly govern the power split among the 02 power supply units of vehicle to achieve the target characteristic curve. Product attributes, process for vehicle level validation and calibration optimization methodology have been established for Fuel Cell Electric Vehicles. This process is also suitable for benchmark vehicle evaluation.