A Modern Chopper Propulsion System or Rapid Transit Application with High Regeneration Capability

Rapid transit propulsion system requirements are becoming more stringent as increased emphasis on reducing energy consumption, minimizing environmental pollution, increasing safety, and improving creature comforts are being considered. In order to meet these new, sometimes mutually exclusive, requirements, considerable detail must be paid to the overall car system. This fact is not particularly novel; however, an intensive study of all the mentioned requirements resulted in the propulsion scheme to be described. A chopper controlled rapid transit propulsion system with five significant features is discussed: 1) fixed frequency crystal-controlled chopper, 2) separately excited traction motors with flashover protection, 3) minimum contactor operation for mode changes, 4) maximum regeneration commensurate with system capability, and minimum size and weight commensurate with regeneration capability.