Patent ID: 6956343
Filing Date: 2005-10-18
Classification: H02P

Abstract:
1. A method of controlling a physical variable in a two-pulse electronically commutated motor which is configured for connection to a DC power network and which comprises a rotor ( a stator having a stator winding ( a PWM control system for controlling the pulse duty factor (pwm) of currents flowing to the stator winding ( a control apparatus (RGL) for controlling the physical variable by determining the deviation between the actual value and desired value of the physical variable, and for repeatedly calculating a current control input dependent on that deviation; the method comprising the steps of: a) delivering the current to the stator winding in the form of current blocks whose length is controlled by the length of control signals; b) controlling the length (BW) of the control signals for those current blocks by the control apparatus (RGL) as a function of the control input; c) defining a lower limit value for the length of the control signals when the motor is in drive mode; d) defining an upper limit value for the length of the control signals when the motor is in drive mode; e) in at least some of the instances in which the length of a control signal reaches the lower limit value, decreasing the pulse duty factor (pwm) by a first predetermined value by means of the PWM control system; f) in at least some of the instances in which the length of a control signal reaches the upper limit value, increasing the pulse duty factor (pwm) by a second predetermined value by means of the PWM control system.