Multiobjective Optimal Design and Soft Landing Control of an Electromagnetic Valve Actuator for a Camless Engine

This paper presents a multiobjective optimal design and an energy compensation control for the soft valve landing of an electromagnetic valve actuator in internal combustion engines. This axisymmetric and cylindrical actuator is used to achieve continuous and independent valve timing and lifting without mechanical cams, which features a hybrid magnetomotive force with permanent magnet (PM) and electromagnet, and a secondary air gap to prevent the PM irreversibly demagnetizing. The dynamics of the electromagnetic valve are modeled with an equivalent magnetic circuit, which is used to perform both sensitivity analysis and an optimal design function to satisfy multiple objectives, such as magnetic holding force, release current, and its rising time. The energy compensation control in which the positive and negative work of an armature stroke is equalized enables a zero landing velocity to be achieved. The experimental results from a prototype actuator 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.