Simulation of the Performance of an Electrically Turbocharged Engine Over an Urban Driving Cycle

Abstract

The study aimed to estimate the energy recovery potential of a decoupled electric turbocharger and its boosting ability in a spark-ignition engine using simulation-based work. Passenger vehicle engines operate at low loads and speeds, requiring characterization and estimation of energy available for recovery under normal driving conditions. A 1-D numerical model of the engine and boosting system was developed to predict energy recovery over steady-state full-load operating conditions, part-load conditions, and actual, transient Klang Valley and Kuala Lumpur drive cycle conditions. The electric turbocharged engine consists of two motors and a battery pack, which were modeled and utilized using GT-Power engine simulation software. The study found that the electrical turbocharger system could recover 0.57 kW and 0.50 kW at 2500 rpm and 3000 rpm, respectively. Part-load studies showed that the maximum amount of electrical energy recovered at 6500 rpm was 5.25 kW. Drive cycle analysis revealed that fuel consumption was the same for both engine models due to the similar turbocharger output performance and lower back pressure caused by the recalibrated wastegate controller. This was partially mitigated by the inclusion of two electric motors. Drive cycle analysis revealed that the electric turbocharger can perform better than a conventional turbocharger when optimized.