Adaptive resistor grid fan control

A method of operating an electric drive machine, the method comprising:

• determining a cooling load for a resistor grid coupled to a motor of the electric drive machine;
• selecting, from two or more operation modes of a fan coupled to the resistor grid, an operation mode in which to operate the fan;
• calculating a target fan speed, from a range of fan speeds, according to the cooling load for the resistor grid and the selected operation mode;
• and
• controlling a fan motor such that the fan operates according to the selected operation mode at a fan speed that is at least equal to the target fan speed.

An electric drive machine comprising:

• a resistor grid electrically coupled to a motor of an electric drive machine;
• a fan coupled to the resistor grid, the fan operable in two or more operation modes;
• and
• a control circuit comprising one or more processors and memory structured to store instructions that, when executed by the one or more processors, cause the control circuit to:
• determine a cooling load for the resistor grid;
• select, from two or more operation modes of the fan, an operation mode in which to operate the fan;
• determine a target fan speed, from a range of fan speeds, according to the cooling load for the resistor grid and according to the selected operation mode;
• and
• provide an output corresponding to a target fan speed to the fan.