Design and Experimental Comparison of Energy Management Strategies for Hybrid Electric Buses Based on Test-Bench Simulation

Energy management in hybrid and electric vehicles is a key factor to improve the operational performance and meet the efficiency objectives defined in the transport sector. Thus, optimized energy management strategies (EMSs), before being integrated in a real system, need to be experimentally validated in test-bench platforms in order to identify the possible deviations from the expected simulation-based performance while minimizing the implementation time and field-test on the real application. An economical and flexible mean of validating these strategies is the hardware-in-the-loop simulation. Therefore, this work aims to present the design approach and comparison, by means of experimental tests, of two optimized (simulation-based) EMSs proposed for a hybrid electric bus (HEB) focusing on the real-time operational performance. Both EMSs handle the proper power split behavior of the vehicle demand among a genset (internal combustion engine + electric generator) and a hybrid energy storage system (combining Li-ion batteries with supercapacitors). The experimental platform consists of a scaled test bench emulating the electrical dc grid of a HEB. This test bench, combined with software models to control the power electronic devices, allows us to emulate the real behavior of the genset, battery, supercapacitor, traction, and auxiliary loads.