Medtronic PB560 Valve


we understand the importance of the ventilators during the crisis of COVID-19, and to support our country we decided to design a ventilator,
in our system, we are using the CAMOZZI PWM solenoid valve CP-921-TW2-0711 to contrôle the flow. We have some issues about how to calibrate the duty cycle of the solenoids valves to attend to the preferred Inspiratory Flow. As an example :

Mode =VAC , Vt= 600 ml , Ti = 1s , Flow Pattern = Rectangle

Peak Flow (l/min) = [( Vt(l) * 60 ) / Ti (s) ] = 36 l/min .

In general, 20 < Vt < 2000 ml and 0.10 s < Ti < 3 s, Are you using some sort of equation to attend the preferred Flow?
Could anyone know how Medtronic controls their valve to have the preferred flow?
Best Regard.