Economic MPC-based transient control for a dual-mode power-split HEV

Abstract

The existing research into hybrid electric vehicle (HEV) control is mainly focussed on the optimisation of the power distribution between a conventional internal combustion engine (ICE) and an alternative power source (usually a battery pack), however, transient control, which is a key technique that affects both fuel economy and the drivability of the HEV, has not been fully addressed. Especially in dual-mode power-split HEVs, due to the different dynamic characteristics of the actuators in the transmission, and its complicated speed-torque relationship, transient control also affects the precision of power distribution and the speed of response of the electric output power. To improve the transient control performance, the design of an economic model predictive control (EMPC)-based transient controller for a dual-mode power-split HEV is developed. By incorporating an experimental identification model of a diesel ICE in a control-oriented transmission model, a better coordination among the actuators involved in HEV transmission can be achieved. Moreover, an ICE efficiency index is also added to the objective function to improve ICE fuel efficiency during this transient process. Then, a fast MPC method is applied to reduce the on-line computation effort required of the proposed control algorithm. By the flexible application of the EMPC and an innovative ICE model which is suited to the control-oriented model in EMPC, the transient control performance was improved. The effectiveness, and the real-time performance, of the control algorithm are validated by way of MATLAB™/Simulink-based simulations, as well as test-bed experiments combined with the use of the RapidECU platform.