Patent ID: 7759884

Claim:
A method of commutating an electronically commutated motor ( 120 ), which motor comprises a rotor ( 124 ), at least one phase ( 126 ), a power stage ( 122 ) for influencing a motor current ( 320 ) flowing through the at least one phase ( 126 ), a memory ( 131 ) adapted for storing a default time span value (T_Default), and a rotor position sensor ( 140 ) for generating a rotor position signal ( 182 ), which method comprises the following steps: A) after a change of the rotor position signal ( 182 ), which change is associated with a pole change that follows a commutation of the motor current ( 320 ) through the at least one phase ( 126 ) and that is referred to hereinafter as a first pole change, ascertaining a first value (I_MEAS(HCnt−1)) of the motor current; B) after a predetermined time span (T_Default+T_Offset(HCnt−1)) has elapsed since the first pole change, carrying out a new commutation; C) after a change of the rotor position signal ( 182 ), which change follows the new commutation and is associated with a pole change that is hereinafter referred to as a second pole change, ascertaining a second value for the motor current (I_MEAS(HCnt)); D) ascertaining any deviation between the first value (I_MEAS(HCnt−1)) and second value (I_MEAS(HCnt)), and as a function of said deviation, modifying the value for the predetermined time span (T_Default+T_Offset(HCnt−1)) in order to bring about, when this modified value is applied during commutation control, an improved equalization of the first value for the motor current and the second value for the motor current.