Abstract: A method and apparatus for controlling an electric aircraft. An apparatus comprises a motor, a power source, and a four-quadrant controller. The motor operates in four quadrants of operational space and operates in one of an accelerating state and a regenerative braking state. A total current flows through the motor. The power source is connected to the motor, and when the motor operates in the regenerative braking state, the total current flows through the power source. The power source has a maximum allowable current. The four-quadrant controller is programmed to identify a recharging parameter, brake the motor to initiate the regenerative braking state when the recharging parameter is present, recharge the power source with the total current during the regenerative braking state, and control a duty cycle of the motor such that the total current does not exceed the maximum allowable current during the regenerative braking state.

Abstract: A method and apparatus for controlling a motor. The motor comprises windings. A switch bridge comprising a plurality of switches is configured to couple a power source to the windings. A motor controller is configured to control the plurality of switches. An undesired condition identifier is configured to identify an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source. An undesired condition reducer is configured to reduce the undesired condition in response to identifying the undesired condition by the undesired condition identifier.

Abstract: A method and apparatus for controlling a group of electric motors. A controller is configured to identify a group of switching frequencies for a desired signature for the group of electric motors. The controller is further configured to control switching of a current supplied to the group of electric motors with the group of switching frequencies for the desired signature identified.

Abstract: A method and apparatus for controlling an electric motor. A switching frequency meeting a desired operating condition is identified from information relating to operation of the electric motor. A switching of a current supplied to the electric motor with the switching frequency identified is controlled.

Abstract: A method for controlling an electric motor. A desired speed is identified for the electric motor during operation of the electric motor. A voltage is identified to cause the electric motor to turn at the desired speed. The voltage is applied to the electric motor and actively controlled during operation of the electric motor.

Abstract: A method and apparatus for controlling a motor. The motor comprises windings. A switch bridge comprising a plurality of switches is configured to couple a power source to the windings. A motor controller is configured to control the plurality of switches. An undesired condition identifier is configured to identify an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source. An undesired condition reducer is configured to reduce the undesired condition in response to identifying the undesired condition by the undesired condition identifier.

Abstract: A method and apparatus for controlling operation of an electric motor. A controller is configured to identify a position of a disc relative to a plate with coils physically associated with the plate. The controller is further configured to control a current sent to the coils based on the position of a disc. The disc is configured to move such that a closest point between the disc and the plate changes along a periphery of the disc.

Abstract: A method and apparatus for controlling a motor. The motor comprises windings. A switch bridge comprising a plurality of switches is configured to couple a power source to the windings. A motor controller is configured to control the plurality of switches. An undesired condition identifier is configured to identify an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source. An undesired condition reducer is configured to reduce the undesired condition in response to identifying the undesired condition by the undesired condition identifier.

Abstract: A method and apparatus for controlling an electric motor. A controller is configured to identify a start time for a signal based on a back electromotive force present in an electric motor during operation of the electric motor. The start time is for a position of a rotor relative to a group of coils. The controller is further configured to send the signal to the group of coils using the start time identified. An effect of the back electromotive force on the signal is reduced.

Abstract: A method and apparatus for controlling an electric aircraft is presented. An apparatus comprises a controller. The controller is configured to identify a state for an electric aircraft. The controller is further configured to identify a group of recharging parameters for a group of electric motors in an electric propulsion system. The electric propulsion system is configured to move the electric aircraft based on the state for the group of electric motors for the electric aircraft. The controller is still further configured to recharge a power source for the electric aircraft using the group of recharging parameters to control recharging of the power source with the group of electric motors when a recharge state is present for the electric aircraft.

Abstract: A method and apparatus for controlling operation of an electric motor. A controller is configured to identify a position of a disc relative to a plate with coils physically associated with the plate. The controller is further configured to control a current sent to the coils based on the position of a disc. The disc is configured to move such that a closest point between the disc and the plate changes along a periphery of the disc.

Abstract: A method and apparatus for controlling an electric motor. A controller is configured to identify a start time for a signal based on a back electromotive force present in an electric motor during operation of the electric motor. The start time is for a position of a rotor relative to a group of coils. The controller is further configured to send the signal to the group of coils using the start time identified. An effect of the back electromotive force on the signal is reduced.

Abstract: A method and apparatus for controlling a group of electric motors. A controller is configured to identify a group of switching frequencies for a desired signature for the group of electric motors. The controller is further configured to control switching of a current supplied to the group of electric motors with the group of switching frequencies for the desired signature identified.

Abstract: A method and apparatus for controlling a motor. The motor comprises windings. A switch bridge comprising a plurality of switches is configured to couple a power source to the windings. A motor controller is configured to control the plurality of switches. An undesired condition identifier is configured to identify an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source. An undesired condition reducer is configured to reduce the undesired condition in response to identifying the undesired condition by the undesired condition identifier.

Abstract: A method for controlling an electric motor. A desired speed is identified for the electric motor during operation of the electric motor. A voltage is identified to cause the electric motor to turn at the desired speed. The voltage is applied to the electric motor and actively controlled during operation of the electric motor.