Power Balancing of Internal Combustion Engines – A Time and Frequency Domain Analysis

Abstract

Power balancing of internal combustion engines is studied in time and frequency domains. Speed measurements at the flywheel and the load side are used to estimated the torque applied to the flywheel. The power contributions during the cylinder-wise work phases are estimated by integrating the reconstructed torque, and a controller which adjusts the fuel injections to reduce power unbalances is applied. A convergent power balancing algorithm is presented for multi-cylinder engines, where the work phases of the individual cylinders may overlap. This time-domain method is verified against previous frequency-domain approaches. The analysis shows that for engines with flexible crankshafts, the time-domain method performs in general differently from frequency-domain cylinder balancing approaches. The feasibility of the power balancing algorithm is investigated by simulations and full-scale tests on a large diesel power plant engine.