Patent ID: 7454985
Filing Date: 2008-11-25
Classification: F04D,G01D

Abstract:
1. A method for determining the hydraulic flow rate in a pump driven by a synchronous electric motor, said motor being of the type comprising a rotor, equipped with a permanent magnet, which is rotation-driven by the electromagnetic field generated by a stator equipped with pole pieces with relevant windings, the method comprising the step of: indirect measuring of said flow rate through the acquiring at least one pump operation variable, comparing the value of said variable within a predetermined correlation table and determining a corresponding flow rate value, and determining a corresponding flow rate value wherein said step of acquiring said at least one pump operation variable acquires a load angle or delay θ, i.e. a phase shift angle between a network voltage applied to the motor terminals and the counter-electromotive force generated by adding the effects of the stator flux and of the flux induced by the rotor permanent magnet rotation and in that said correlation table links flow rate values and load angle values.