Method for propelling and retarding off-road haulers

A method of operating an electrical propulsion and distribution system for a vehicle, said vehicle comprising an internal combustion engine, an AC generator for generating AC power from said engine and applying the same to an AC grid, a trolley converter coupled to said AC grid and to DC terminals at which external DC power is received, and an electrical propulsion motor coupled to said AC grid via field and armature converters, comprising:

• sensing the presence of DC power applied to said DC terminals;
• inverting said DC power applied to said DC terminals into AC power with said trolley converter;
• gating said trolley converter to apply said inverted DC power to said AC grid simultaneously and in combination with AC power from said AC generator;
• and
• powering said electrical propulsion motor with said inverted DC power in combination with the AC power from said AC generator.

A method of operating an electrical propulsion and distribution system for a vehicle, said vehicle comprising an internal combustion engine, an AC generator for generating AC power from said engine and applying the same to an AC grid, a trolley converter coupled to said AC grid and to DC terminals at which external DC power is received, and an electrical propulsion motor coupled to said AC grid via field and armature converters, comprising:

• sensing the presence of DC power applied to said DC terminals;
• inverting said DC power applied to said DC terminals into AC power with said trolley converter;
• gating said trolley converter to apply said inverted DC power to said AC grid;
• powering said electrical propulsion motor with said inverted DC power;
• activating a retard mode by controlling said motor converter so that power is supplied to said AC grid by said motor to power said AC generator as a synchronous motor;
• and
• coupling a retard load to the AC grid during said retard mode, to dissipate energy in excess of that provided to said AC generator by said motor.