Patent ID: 7268502

Claim:
A method of controlling synchronous running of a plurality of electronically commutated motors ( 22 , 24 , 26 ; 110 , 112 , 114 , 116 ) that each comprise: a stator having at least one stator winding ( 40 , 42 , 44 ; 120 , 122 ; 126 , 128 ; 132 , 134 ; 138 , 140 ) a permanent-magnet rotor ( 28 , 30 , 32 ; 118 , 124 , 130 , 136 ), and at least one arrangement, associated with the respective motor, for sensing the rotor position thereof and for generating a rotor position signal (H 1 , H 2 , H 3 , H 4 ), and having an energization arrangement ( 46 ; 158 , 172 ) to which the stator windings of the motors are connected, comprising the steps of: detecting occurrence of a predetermined state of respective rotor position signals (H 1 , H 2 , H 3 , H 4 ) of said motors, namely a change associated with passing a pole, from a first rotor position signal value to a second rotor position signal value, and subsequent to said change of said signal value in each of said motors, commutating the current in all the motors simultaneously.