Cooling system for an electric drive machine and method

A machine having an electric drive system, the electric drive system including an engine that is connected to a generator, the generator having an electrical output connected to a rectifier, the rectifier connected to an inverter, the inverter connected to an electric drive motor, the machine further comprising:

• a cooling duct in fluid communication with a first component and a second component;
• a fan motor operating a blower disposed within the cooling duct;
• a first temperature sensor disposed to measure a first component temperature and to provide a first component temperature sensing signal;
• a second temperature sensor disposed to measure a second component temperature and to provide a second component temperature sensing signal;
• and
• an electronic controller configured to:
• provide a motor command signal;
• receive the first and second temperatures;
• calculate a first temperature difference between the first temperature and the first temperature limit and generate a first blower command for the motor based on the first temperature difference;
• calculate a second temperature difference between the second temperature and the second temperature limit to generate a second blower command for the motor based on the second temperature difference;
• calculate a feed-forward blower motor command based on a machine load factor;
• select the greater of the first blower command, the second blower command, and the feed-forward blower command to be a maximum command, and
• determine and provide the motor command signal to the motor based on the maximum command.

A method of operating a blower disposed in a convective cooling system associated with at least a first component and a second component of a machine, the cooling system including a cooling duct that directs a cooling flow of air toward the first component and the second component, and a blower operating under the control of a controller to direct a cooling flow of air through the cooling duct, the method comprising:

• sensing a first temperature of the first component and providing a first temperature signal indicative of the first temperature;
• sensing a second temperature of the second component and providing a second temperature signal indicative of the second temperature;
• comparing the first temperature signal to a first temperature limit to yield a first temperature difference;
• comparing the second temperature signal to a second temperature limit to yield a second temperature difference;
• calculating a first desired airflow based on the first temperature difference;
• calculating a second desired airflow based on the second temperature difference;
• determining a feed-forward airflow based on at least one operating parameter of the machine that is indicative of a load factor of the machine;
• selecting the greater of the first desired airflow, the second desired airflow and the feed-forward airflow to be a maximum desired airflow;
• and
• operating the blower to generate a flow of air in the cooling duct that is at least equal to the maximum desired airflow.