Optimized Control Strategies for Fast Switching Solenoid Valves

In this paper, the effects of different strategies for energizing solenoid valves are studied. These strategies are chosen subject to obtain soft-landing and concurrently minimization of power dissipation. A lumped parameter reluctance model is used to reflect the electrical and magnetic properties of a dual coil high-speed solenoid digital valve. This model is validated by stationary and transient experiments. The data from the model are in good agreement with the measurements. It is shown that retarded magnetic flux increase and spatial field diffusion phenomena are the major limiting factors for the feasible switching frequency of the spool motion. Thus, it is proposed to match the control strategy to these effects in order to reduce power dissipation in the coil as well as in the magnetic core. A control strategy that minimizes the power losses is obtained within a trajectory generating framework where the differential flatness property is used as a key enabler for efficient optimization schemes. The validity of the proposed hypothesis is demonstrated in several simulations, where the method using voltage profiles is compared against state of the art boost and hold energizing schemes.