A method for operating a permanent magnet synchronous motor comprises setting a maximum power, determining a current vector and an output voltage vector in the dq coordinate system. A setpoint amount for a setpoint voltage vector is calculated on the basis of the maximum power, the current vector and the output voltage vector. The setpoint voltage vector is generated with the setpoint amount, and then operating the permanent magnet synchronous motor at least with the setpoint voltage vector.

This disclosure describes at least embodiments of an aircraft monitoring system for an electric or hybrid airplane. The aircraft monitoring system can be constructed to enable the electric or hybrid aircraft to pass certification requirements relating to a safety risk analysis. The aircraft monitoring system can have different subsystems for monitoring and alerting of failures of a component, such as a battery pack, a motor controller, and/or a motors. The failures that pose a greater safety risk may be monitored and indicated by one or more subsystems without use of programmable components.

A method for operating an electrical circuit, wherein the electrical circuit includes a DC converter, an inverter and an electric machine, wherein the inverter is connected on the direct current side to the output of the DC converter and on the alternating current side to the electric machine, wherein the electric machine is operated using a torque specification and/or a rotational speed specification, wherein the level of the output voltage of the DC converter is set as a function of a current torque specification and/or a current rotational speed specification.

A method for operating a permanent magnet synchronous motor comprises setting a maximum power, determining a current vector and an output voltage vector in the dq coordinate system. A setpoint amount for a setpoint voltage vector is calculated on the basis of the maximum power, the current vector and the output voltage vector. The setpoint voltage vector is generated with the setpoint amount, and then operating the permanent magnet synchronous motor at least with the setpoint voltage vector.

A dual motor system includes a first motor providing a lower speed range and a second motor providing a higher speed range, wherein the motors are coaxially arranged and aligned on and drive a common shaft, and a motor control system controlling the speed of the first motor and engaging the second motor as needed. The first motor is a variable speed motor providing a lower two-thirds of a full speed range, and the second motor is an induction motor providing the upper one-third in the form of one or more discrete fixed speeds. The system may include a transformer including a first winding tap which provides a first higher speed, and a second winding tap which provides a second higher speed. The system may also include a flow control system for automatically controlling the speed of the motors for particular applications, such as flow control in a pool.

A system to reconfigure a motor from induction mode to synchronous mode at a zero crossing of the field voltage during startup using only stator current signals is described herein. The zero crossing may be detected by asymmetry induced in the stator currents by a current asymmetry inducing module of the motor. The current asymmetry inducing module may include a resistor and diode in series and in parallel with a discharge resistor of the field windings. Asymmetry is induced in the current obtained from the stator, and used to determine a zero crossing of the field voltage. Upon the rotor reaching a startup frequency and the detected zero-crossing of the field voltage, the motor may be reconfigured from induction mode to synchronous mode.

A system to reconfigure a motor from induction mode to synchronous mode at a zero crossing of the field voltage during startup using only stator current signals is described herein. The zero crossing may be detected by asymmetry induced in the stator currents by a current asymmetry inducing module of the motor. The current asymmetry inducing module may include a resistor and diode in series and in parallel with a discharge resistor of the field windings. Asymmetry is induced in the current obtained from the stator, and used to determine a zero crossing of the field voltage. Upon the rotor reaching a startup frequency and the detected zero-crossing of the field voltage, the motor may be reconfigured from induction mode to synchronous mode.

A drive system includes an electric machine with a rotor having an externally excited rotor winding, and a stator having stator winding sets, each with at least three stator windings; a control unit controlling the electric machine supply the rotor winding with a first current signal, and the stator windings with different current phases of a multi-phase second current signal, thus producing a rotary magnetic field generating a torque on the rotor; at least one inverter, the multi-phase current signal being provided based on the at least one inverter; and at least one rectifier providing a DC signal, the first current signal being based at least on the DC signal and on an AC harmonics component. Harmonics of a current phase of the multi-phase current signal are reduced based on the supply of the AC harmonics component.

A drive system includes an electric machine with a rotor having an externally excited rotor winding, and a stator having stator winding sets, each with at least three stator windings; a control unit controlling the electric machine supply the rotor winding with a first current signal, and the stator windings with different current phases of a multi-phase second current signal, thus producing a rotary magnetic field generating a torque on the rotor; at least one inverter, the multi-phase current signal being provided based on the at least one inverter; and at least one rectifier providing a DC signal, the first current signal being based at least on the DC signal and on an AC harmonics component. Harmonics of a current phase of the multi-phase current signal are reduced based on the supply of the AC harmonics component.

A method is for a circuit for a motor comprising first and second phase windings. The method comprises receiving alternating current (AC) power from the first and second phase windings at a direct current (DC) power supply and converting the AC power to DC power and receiving AC power from the first and second phase windings by at least one power switch between the first and second phase windings and switching the AC power by the at least one power switch. The method includes preventing the DC power supply from collapsing, by a first component connected to the DC power supply, when the at least one power switch is on during a first portion of an AC cycle and preventing the DC power supply from collapsing, by a second component connected to the DC power supply, when the at least one power switch is on during a second portion of the AC cycle.