Abstract: A control system (15) for controlling a full bridge converter to compensate the reactive power consumed by an inductive position sensor for a rotor of an electrical machine supported by at least one active magnetic bearing is proposed. The inductive position sensor is supplied by an alternating current source. The control system (15) includes a phase shift determining means (26) to determine a phase shift (SP) between a supply voltage (VS) and a supply current (IS) delivered by the source. A first control loop (22) controls the amplitude (AC) of a control signal (SC) from the phase shift (SP). A second control loop (23) controls the phase of the control signal (SC). A third control loop (24) controls a voltage reference (VR). A controlling means (25) controls a full bridge converter according to the control signal (SC).