Richard M Slagle

US Patent:

45491194, Oct 22, 1985

Filed:

Apr 27, 1984

Appl. No.:

6/604750

Inventors:

Richard M. Slagle - Grove City PA

Assignee:

Joy Manufacturing Company - Pittsburgh PA

International Classification:

H02P 772

US Classification:

318 11

Abstract:

Method and apparatus for controlling DC traction motors on opposite sides of a vehicle, particularly a mining machine, by means of an SCR converter. The motors are accelerated while controlling the firing angles of the SCR's such that the current and voltage supplied to the motors increase along ramps until desired normal operating values of voltage and current are reached with the voltage across the series-connected motors being of a substantially greater value than the value it would be if the motors were connected in parallel. In contrast to prior art systems, the traction motors are maintained in a series-connected configuration during normal, essentially steady-state operation; while the voltage across the motors is maintained at said substantially higher value. When one of two drive wheels connected to the traction motors is slipping, the motors are connected in parallel to increase torque with a corresponding decrease and increase in voltage and current, respectively. By virtue of the fact that the motors operate in series during normal, sustained operation, the total current drawn by the motors is reduced, thereby reducing heating effects and the necessity of large diameter power lead-in cables.