ELECTRICAL GENERATING APPARATUS

• US 3,858,107 A
• Filed: 01/08/1974
• Issued: 12/31/1974
• Est. Priority Date: 01/09/1973
• Status: Expired due to Term

• Current Assignee: Christopher John Yarrow, Ronald Johnson
• Original Assignee: Christopher John Yarrow, Ronald Johnson
• Inventors: Yarrow, Christopher John, Johnson, Ronald
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/431,738
• Time in Patent Office: 357 Days
• Field of Search: 321/6,8,61-69 322/32,26,93,DIG.5 310/68D,160,DIG.3
• US Class Current: 322/26
• CPC Class Codes: H02K 29/10 using light effect devices
• CPC Class Codes: H02K 47/08 Single-armature converters
• CPC Class Codes: H02P 2101/30 for aircraft
• CPC Class Codes: H02P 9/42 to obtain desired frequency without varying speed of the generator

Abstract

An electrical generating apparatus includes a d.c. source, e.g. a self exciting engine driven generating set, and an inverter including an armature winding, with tappings spaced around the armature winding. Switch means intermittently connect the d.c. source to the tappings to produce an a.c. output. The switch means may include thyristors triggered by a position sensing device on a shaft driven at a constant speed, a d.c. supplied field winding on this shaft within the armature winding effecting turning off of these thyristors by periodically reversing the emf in the armature winding.

Claims

1. Electrical generating apparatus comprising a source of d.c. supply and an inverter, said inverter comprising an armature winding, a freely rotatable field winding associated with said armature winding, a plurality of connections spaced around said armature winding, and switch means for intermittently connecting said d.c. source to said connections in synchronism with the rotation of the field winding in a manner in which an a.c. output will be produced in use at at least one terminal of said armature winding, the frequency of the a.c. output being related to the speed of operation of said switch means and the rotating field winding.

2. Apparatus as claimed in claim 1, in which said source comprises an electrical a.c. generator, a variable speed prime mover for driving said generator, and rectifying means for rectifying the variable frequency a.c. output of said generator.

3. Apparatus as claimed in claim 1 in which said switch means comprises a plurality of semi-conductor switching elements equal in number to twice the number of said connections around said armature winding, each connection being connected to the junction of two series connected semi-conductor switching elements which are connected across said source of d.c. supply.

4. Apparatus as claimed in claim 3, comprising a shaft rotatable with said rotatable field winding, means on said shaft for switching the plurality of semi-conductor switching elements from a non-conductive to a conductive state in a predetermined sequence, the speed of rotation of said shaft determining the rate of switching said semi-conductor switching elements.

5. Apparatus as claimed in claim 4 in which said semi-conductor switching elements are in the form of thyristors, and a light sensitive firing circuit being associated with each thyristor.

6. Apparatus as claimed in claim 5 in which said means mounted on said shaft comprises an apertured drum, a light source within said drum, and a plurality of fiber optical cables arranged around said drum, said means upon rotation being adapted to allow light to pass from said light source to said plurality of fiber optical cables, and being associated, respectively, with the thyristor firing circuits.

7. Apparatus as claimed in claim 2, comprising an exciter armature rotatable with the rotatable field winding, and a fixed exciter field winding connectable to said d.c. supply, said d.c. supply to the rotatable field winding being derived through rectifiers from said exciter armature.

8. Apparatus as claimed in claim 7 in which said exciter field winding is a three phase winding having switch means for alternatively connecting it to the d.c. supply and to the output of the variably driven a.c. generator so as to act together with the exciter armature winding as an a.c. motor for starting purposes.

9. Apparatus as claimed in claim 2 in which the a.c. generator includes a shaft, and an overrunning clutch connecting said shaft to the inverter shaft so as to prevent the inverter shaft from rotating more slowly than the a.c. generator shaft.