Abstract: A pump with magnetically-levitated rotor includes a position sensor having an eddy-current sensor coil that operates as a resonating element in a low frequency oscillator located within the pump housing. The oscillator is operably interconnected with additional electronics that shift the frequency of the oscillator output signal to a lower frequency. The lower frequency signal is directed to a frequency measurement circuit that provides a value representing a position of the rotor.

Abstract: Methods for determining a viscosity of a fluid passing through a fluid pump are disclosed. An amount of energy associated with axially moving a rotor may be determined and correlated to a viscosity of fluid interacting therewith. For example, energy associated with a response of a suspended rotor may be determined. The amount of energy may be correlated with a viscosity of the fluid interacting with the rotor. The rotor may be initially unsuspended and an amount of energy associated with suspending the rotor may be determined and correlated with a viscosity of fluid interacting with the rotor. In another method, subsequent to suspending a rotor, the rotor may be unsuspended and an energy response of the rotor may be quantified to determine a viscosity of fluid passing through the pump. Systems for determining a viscosity of a fluid are also disclosed.