A pre-charging system for a capacitor in a voltage inverter for an electric motor is provided. It determines an error signal et at an instant t in accordance with the equation et=yt\u2212XtTHt\u22121, where Ht\u22121 is a vector made up of L coefficients of an identification filter having a finite impulse response representative of the impulse response of the system and XtT=. The dual role of the air removal system is to removeaspirate micro-air bubbles from the venous side of the circuit and to prevent large air boluses from entering the centrifugal pump and stopping the pump.