Energy compensation method for soft-landing control in camless engine with electromagnetic valve actuator

This paper proposes a control strategy involving energy compensation for the soft-landing of an electromagnetic valve actuator in internal combustion engines. This axisymmetric and cylindrical actuator features a hybrid magnetomotive force with permanent magnet and electromagnet, and a secondary air gap to prevent the permanent magnet irreversibly demagnetizing. It is a straightforward theory in which the positive and negative work of an armature stroke is equalized, enabling a zero landing velocity to be achieved. The resultant of positive and negative work is a function of valve landing velocity, which depends on the release current that releases the armature from one seating position, and the landing current that attracts the armature to the opposite seating position. The magnitude and duty cycle of the release and landing currents are investigated for soft-landing via observation of armature displacement and velocity. The experimental results show that the landing velocity can be greatly reduced by adjusting the duty cycle of the landing current, and the actuating power is greatly reduced after the energy compensation control is applied.