Electric machines with air gap control systems, and systems and methods of controlling an air gap in an electric machine

An air gap controller configured to control a length of an air gap in an electric machine, the air gap controller comprising:

• one or more processors;
• and
• one or more memory devices that includes computer-readable instructions that, when executed by the one or more processors, perform a process comprising:
• determining an air gap length value for the electric machine,
• comparing the determined air gap length value to an air gap target value, and
• outputting one or more control commands to one or more controllable devices when the determined air gap length value differs from the air gap target value by a predefined threshold,
• wherein the one or more control commands are configured to impart a change to one or more operating parameters to adjust the length of the gap between an outer surface of a rotor core and an inner surface of a stator core of the electric machine, and
• wherein the air gap target value comprises an adjusted air gap target value, the adjusted air gap target value having been provided by an air gap target model.