Control of Auxiliary Power Unit for Hybrid Electric Vehicles

Auxiliary power units (APUs) are widely used for electric power generation in modern hybrid electric vehicles. In the consideration of the APU, a common shaft connects an internal combustion engine and an electrical induction motor which is used as a starting motor and as a battery charger. Dynamic models of both engine and motor are used for the design of the APU controller. A field oriented control scheme and a decoupling controller with two independent current control loops is used for the motor. A torque controller, based on a sliding mode torque estimator, regulates the engine transients. The control of the whole APU is obtained by coupling the engine and motor controllers through a reference governor of the requested power. Numerical experiments on a realistic case study show good performance both in steady state and during transients.