Real-time brake torque estimation for internal combustion engines

Abstract

Presented is a real-time engine brake torque estimation model where the instantaneous measured engine speed serves as the model input. The model is comprised of notch filters executed in the crank-angle domain to extract mean engine speed and the nth frequency component from the instantaneous engine speed signal in real-time. Here n denotes the number of engine cylinders. Moreover, the engine brake torque estimation is separated into two parts: steady-state and transient. It will be shown that the nth harmonic (in units of periods per engine cycle) of engine speed and mean engine speed are sufficient to estimate the engine brake torque. The steady-state portion of the model is developed using orthogonal least-squares estimation and results in a model with 15 regressors for our particular case. The transient portion is identified using a time domain identification method. Validation of the engine brake torque model is provided using a computational engine model for a 6-cylinder heavy duty diesel engine. Transient engine speed and torque conditions in the presence of sensor noise are evaluated as well as cylinder power imbalance scenarios.