The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 11, 2000
Filed:
Jul. 23, 1999
Alan P French, Florissant, MO (US);
Emerson Electric Co., St. Louis, MO (US);
Abstract
A method and apparatus for controlling the average voltage applied to a phase winding of a reluctance machine during a period of current increase, controlling the current when a desired current is reached, and controlling the voltage applied during a period of current decrease, to improve machine efficiency and thereby reduce acoustical noise produced by the machine, and unwanted vibration. The apparatus comprises circuitry and associated elements which are operable to switch the phase winding into circuits which apply either a positive DC voltage, a zero voltage, or a negative DC voltage, to increase, maintain, or decrease the current in the winding. The timing and the rate of the switching is controlled as a function of the angular position and speed of a rotor of the reluctance machine, the torque output of the machine, and the desired speed or torque. A method is provided whereby a duty cycle corresponding to a specific reluctance machine, as well as to specific operating parameters of the machine at a given rotor position, speed, and torque, is calculated by the controller for applying voltage to the phase winding during the period of current increase to increase the current from at or near zero to a desired peak current. Additionally, a method is provided for calculating a duty cycle for the time at which the phase is de-energized, corresponding to a specific reluctance machine, and to specific operating parameters of the machine at a given rotor position, speed, and torque, as well as a method for changing the duty cycle to drive the current in the winding to zero or near zero. The calculation of the appropriate duty cycle for the specific operating conditions of the reluctance machine controls the net average voltage applied, has been found to reduce abrupt changes in the current. This reduction correlates into reduced abrupt changes in the magnetic flux, resulting in reduced acoustic noise and unwanted vibration.