×

Motor drive system for an electric mining shovel

  • US 4,263,535 A
  • Filed: 09/29/1978
  • Issued: 04/21/1981
  • Est. Priority Date: 09/29/1978
  • Status: Expired due to Term
First Claim
Patent Images

1. In a drive system for a mining machine having a hoist motor, a crowd motor and a swing motor, the combination comprising:

  • a rectifier circuit having inputs connected through lines to a source of a.c. power and an output terminal at which d.c. power is produced;

    disconnect means connected to said lines and being operable in response to a disable signal applied to a power enable input to disconnect said rectifier circuit from said a.c. power source;

    a d.c. bus connected to said rectifier output terminal;

    a set of inverters, each having an input connected to said d.c. bus, each having an output connected to one of said motors and each being operable in response to signals from an associated inverter control circuit to deliver power to its attached motor from said d.c. bus and to regenerate power to said d.c. bus from its attached motor; and

    a power monitor and control circuit which includes;

    a. voltage sensing means coupled to said a.c. power source for generating an analog signal which is proportional to the voltage applied to the inputs of said rectifier circuit;

    b. comparator means connected to said voltage sensing means for generating a preselected logic signal when said analog signal drops below a predetermined level;

    c. timer means connected to said comparator means and being enabled by said preselected logic signal to generate said disable signal to said disconnect means power enable input when said preselected logic signal is present for a preselected time interval; and

    d. means connected to said d.c. bus for generating a reduction signal to each of said inverter control circuits which reduces the power delivered by said inverters to their attached motors when the voltage of said d.c. bus drops below a preselected level.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×