Techniques to control the electricity generation in a series hybrid electrical vehicle

Abstract

In a series hybrid electric vehicle (SHEV), an electric generator feeds a DC busbar (containing an electrochemical accumulator), which, in turns, feeds the vehicle traction system. A very important part of the vehicle is its control system, which has to maximize the vehicle efficiency while keeping the emissions within predetermined limits. To attain this goal, it can act in two ways: (1) it can switch the electric generator ON or OFF, and (2) when in the ON state, it can impose a given power to be delivered. To choose the control actions to perform it needs (a) an algorithm to understand the behavior of the battery (determine the state-of-charge, maximum power, losses) and (b) an algorithm to make some forecast of the system load (i.e., the power required in the future of the trip, as a function of time). This paper discusses the main problems that arise when trying to synthesize the control system of the vehicle, taking into account issues (a) and (b). Some lab tests are also presented in which some of the proposed control techniques are experimentally checked.