Dynamic braking for a three phase motor

• US 3,975,668 A
• Filed: 09/25/1972
• Issued: 08/17/1976
• Est. Priority Date: 09/25/1972
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Davie, Walter C.
• Primary Examiner(s): Rubinson, Gene Z.
• Application Number:
  US05/291,853
• Time in Patent Office: 1,422 Days
• Field of Search: 318/211, 318/212, 318/225, 318/226, 310/12, 322/28
• US Class Current: 318/762
• CPC Class Codes: H02P 3/24 by applying dc to the motor

Abstract

Method and apparatus for dynamically braking a multiphase motor wherein, in a first embodiment, the stator windings of the motor are connected in a six winding delta configuration and direct braking current is applied between two center taps of the configuration. A damping diode is connected across two of the delta center taps to minimize voltage transients in the windings when the direct current is removed.

In a second embodiment, the stator windings are connected in a twisted Y--Y configuration, the connections to the neutral points of the two Y'"'"'s of one phase winding set being interchanged and direct braking current being introduced between the two neutral points. A damping diode is connected between the center points of each Y to minimize voltage transients in the windings when the direct current is removed.

Claims

1. Apparatus for dynamically braking a motor operable from a source of three-phase current comprising:

a motor stator section whose windings are connected in a delta configuration, each side of the delta comprising at least two windings connected at a center tap, said three-phase current being applied to the delta terminal points,

a source of d.c. current, and

switch means for connecting said source of d.c. current between two of said center taps of said delta configuration when the three-phase current source is removed from the delta terminal points whereby said motor is dynamically braked.

2. The apparatus as defined in claim 1 further including means connected between said two center taps for minimizing voltage transients in the windings when said source of d.c. current is removed from said delta center taps.

3. The apparatus as defined in claim 2 wherein said minimizing means comprises a diode.

4. The apparatus as defined in claim 1 wherein said motor drives a shaft upon which a plurality of magnetic disk units are disposed in a space stacked arrangement for rotation in planes parallel to one another, said disks being secured on said shaft as a unitary assembly.