Direct drive electrically-geared turbofan

A turbofan engine, comprising:

• a fan;
• a turbine enclosure, comprising:
• an air intake at an upstream end;
• a compression section downstream of the air intake;
• a combustion section downstream of the compression section;
• a turbine section downstream of the combustion section;
• and
• an exhaust at a downstream end;
• a first spool shaft coupled with a first compressor of the compression section and with a first turbine of the turbine section;
• an electrical gearbox located upstream of the turbine enclosure, the electrical gearbox including a first magnetic gearbox assembly connected to the fan and a second magnetic gearbox assembly connected to the first spool shaft, wherein the electrical gearbox is configured to transfer rotational energy over an air gap between the first magnetic gearbox assembly and the second magnetic gearbox assembly to the fan rotating at a first rotational speed from the first spool shaft rotating at a second rotational speed;
• and
• a speed controller coupled to the electrical gearbox and configured to selectively couple and decouple the first magnetic gearbox assembly with the second magnetic gearbox assembly over the air gap to adjust the first rotational speed to a variable fan reference speed while maintaining the second rotational speed at a constant rate,
• wherein the first magnetic gearbox assembly is configured to couple and decouple with the second magnetic gearbox assembly by opening and closing a switch in a winding circuit,
• wherein the adjustment of the first rotational speed of the fan is based on a difference between the variable fan reference speed for the fan and a measured speed of the fan, wherein the variable fan reference speed is based on operating conditions of the fan and thrust profile for the turbofan engine,
• wherein the measured speed is based on a measured magnitude of a magnetic field, and
• wherein the speed controller controls the first rotational speed of the fan, based on the difference between the reference speed for the fan and the measured speed of the fan, by increasing or decreasing a duty cycle of the switch, said duty cycle including how often the switch is open or closed.