Patent ID: 6353299
Filing Date: 2002-03-05
Classification: F04D,H02P,Y02B

Abstract:
A method having an automatic controller of a dc brushless motor/blower system providing a specified flow output, comprising the steps of:providing a dc brushless motor/blower system having a dc brushless motor coupled to a blower such that a motor-torque by rotor-speed product (TmÃ—Nm) of the dc brushless motor substantially corresponds to a blower-torque by impeller-speed product (TbÃ—Nb) of the blower at steady state and where the ratio of rotor-speed to blower-speed (Nm/Nb) is known; providing a controller linked to a motor drive that adjusts motor speed Nm in response to control signals from the controller corresponding to a pulse width modulation index M; serving the controller information corresponding to flow command information F; serving the controller information corresponding to one of rotor speed Nm or impeller speed Nb and solving for the other of impeller speed Nb or rotor speed Nm by the known ratio Nm/Nb; solving for required blower torque Tb by a polynomial equation expanded through at least second order terms and such that the blower-torque equation's coefficients vary with the flow command information F according to: Tb=A0F+A1FNb+A2FNb2+ . . . , including extracting the blower-torque equation's coefficients A0F, A1F, A2F . . . , from a database according to the flow command value F;solving for delivered motor torque Tm by another polynomial equation expanded through at least second order terms and such that the motor-torque equation's coefficients vary with the most recent pulse width modulation index M according to: Tm=B0M+B1MNm+B2MNm2+ . . . , including extracting the motor-torque equation's coefficients B0M, B1M, B2M . . . , from a database according to the most recent pulse width modulation index M;comparing, in cases of the ratio Nm/Nb being substantially unity, the required blower-torque (required-Tb) to the delivered motor-torque (delivered-Tm), otherwise the product of required blower-torque by impeller-speed (required-TbÃ—Nb) to the product of delivered motor-torque by rotor-speed (delivered-TmÃ—Nm) and, in any case, responding to inequality by signaling the motor drive with a succeeding most recent pulse width modulation index M which is modified to adjust the motor speed correspondingly.