Patent ID: 8058830

Claim:
An electric drive system for a vehicle comprising: an electric motor configured to provide traction power to the vehicle; a first inverter coupled to the electric motor, the first inverter being configured to provide alternating current to the electric motor; a first energy source coupled to the first inverter, wherein the first inverter is configured to provide power flow between the first energy source and the electric motor; a second inverter coupled to the electric motor, the second inverter being configured to provide alternating current to the electric motor; an internal combustion engine configured to provide mechanical energy; a generator coupled to the internal combustion engine, the generator being configured to convert mechanical energy from the internal combustion engine to electrical energy; a rectifier coupled to the second inverter and the generator, the rectifier being configured to produce a direct current output from the electrical energy provided by the generator, wherein the second inverter is configured to provide power from the rectifier to the electric motor; and a controller coupled to the first inverter, the second inverter, the first energy source, and the internal combustion engine, wherein the controller is configured to: monitor a state of charge of the first energy source; and if the state of charge is less than a threshold value: start the internal combustion engine; operate the first inverter and the second inverter to provide charging power to the first energy source from the internal combustion engine; and stop the internal combustion engine after starting the internal combustion engine if the state of charge is greater than a second threshold value, the second threshold value being greater than the first threshold value.