Dual-Source Energy Storage – Control and Performance Advantages in Advanced Vehicles

This paper introduces a methodology for evaluating and segregating load requirements and characteristics to size hybrid energy source/storage elements for handling the types of loads for which they are best suited. This work focuses on investigating the use of a dual-source battery and ultracapacitor pack in place of the seemingly unattainable (in satisfying cost, power, energy, and reliability requirements) single-battery solution that is being sought for hybrid electric applications. However, this methodology is general enough to be applied (with adequate knowledge of load profiles) to any application with two or more source/storage elements. A prerequisite for segregating loads is to use “expert” knowledge to characterize the various sources’ strengths and weaknesses. Component role segregation should facilitate (1) various control method evaluation for real-time implementation of the multi-source solution (without prior profile knowledge), and (2) optimization routines to further adjust component sizing and control variables to maximize fuel economy objectives and minimize mass, volume, and (possibly) cost objectives. This paper provides the general methodology and an example battery and ultracapacitor combination for a midsize hybrid electric vehicle.