Chapter 1: Introduction
In recent decades, hybrid electric vehicle technology has advanced significantly in the automotive industry. It has now been recognized that the hybrid is the ideal transition from the all-petroleum vehicle to the all-electric vehicle. In popular concepts, the hybrid electric vehicle (HEV) is thought of as a combination of an internal combustion engine (ICE) and an electric motor.
The paramount importance of hybrid vehicle system technology is that the fuel economy can be noticeably increased while meeting the increased stringent emission standards and drivability requirements. Thus, hybrid vehicles can play a crucial role in resolving the world's environmental problems and growing energy insecurity. In addition, hybrid technology has been promoting the technology of the electric motor, power electronics, and batteries to maturity (Chan, 2002; Powers and Nicastri, 2000).
The HEV is a complex system of electrical and mechanical components. Its powertrain control problems are complicated and often have conflicting requirements. Moreover, they are generally nonlinear, exhibit fast parameter variation, and operate under uncertain and changing conditions; for example, the vehicle has to run well on a cold January day in Northern Ontario as well as a sweltering day in Death Valley. Many of the control design objectives are very difficult to formalize and many of the variables of greatest concern are not measurable. The HEV system control is a fundamentally multivariable ...