A propulsion system is described that includes an electrical bus, a generator configured to provide electrical power to the electrical bus, a plurality of propulsors configured to provide thrust by simultaneously being driven by the electrical power at the electrical bus, and a controller. The controller is configured to synchronize a rotational speed of an individual propulsor from the plurality of propulsors with a rotational speed of the generator after the individual propulsor has become unsynchronized with the rotational speed of the generator by controlling at least one of the rotational speed of the generator, nozzle area of the individual propulsor, or a pitch angle of the individual propulsor.

A motor starter and a method for starting an electric motor are disclosed. In an embodiment, the motor starter includes a phase gating unit and a control unit. The phase gating unit is configured to be deactivated via the control unit after an activity period of the phase gating unit has elapsed and is configured to be deactivated during operation after the activity period has elapsed.

A motor starter and a method for starting an electric motor are disclosed. In an embodiment, the motor starter includes a phase gating unit and a control unit. The phase gating unit is configured to be deactivated via the control unit after an activity period of the phase gating unit has elapsed and is configured to be deactivated during operation after the activity period has elapsed.

A system and method for identifying and responding to a condition in which an electric motor fails to start. A rotor core includes slots in which magnets are received to produce an electrical reluctance. A motor controller determines a position of the rotor, uses the determined position to convert a torque demand to a demanded D-axis current value, and compares the demanded value to a supplied D-axis current value. If the demanded value differs from the supplied value by at least a pre-established threshold amount, then the motor is restarted. Otherwise, the difference between the torque demand and an actual current is used to drive a voltage applied to the motor. The controller may also implement a sensorless technology, and may restart the motor if the demanded value differs from the supplied value by at least the threshold amount even if the sensorless technology determines that the motor started.

A replay plate 44 is set to have a vertically and horizontally symmetrical shape when a worm wheel 33 is viewed from its axial direction; the worm wheel 33 is provided with an accommodating concave portion 33g in which the relay plate 44 is housed so as to be recessed in the axial direction; and a part of a non-slidably contacting surface in a slidably contacting surface 44a of the relay plate 44, i.e., a non-slidably contacting surface S is covered with first and second fixing parts 35a, 35b that are provided around the accommodating concave portion 33g and protrude in a direction intersecting with an axial direction of the worm wheel 33, the non-slidably contacting surface being a surface with which the contact plate is not slidably contacted.

A method for identifying the magnetic anisotropy of an electric rotary field machine comprising a rotor and a stator is described, the method comprising the steps of setting injection pulses of equal absolute values during an injection interval, detecting a respective current response in form of current difference vectors, and determining the anisotropy from the voltage vectors and current difference vectors. Such a method should allow identifying of magnetic anisotropy in a simple way. To this end, injection pulses in the three-phase domain are used.

A method for estimating the position of a rotor of a synchronous electrical machine, includes a rotor and a stator coupled to an inverted synchronous electrical machine via a rectifier comprising the following steps: measurement of a current i.sub.abc circulating in the stator of the synchronous electrical machine; determination of two signals in quadrature i.sub.α; i.sub.β according to a stationary reference frame from the current i.sub.abc and isolation of two filtered signals i.sub.αh; i.sub.βh from the two signals in quadrature i.sub.α; i.sub.β; demodulation of the two filtered signals i.sub.αh; i.sub.βh in order to obtain two demodulated signals i.sub.αobs, i.sub.βobs, obtaining of an estimated position {circumflex over (θ)} of the rotor from the two demodulated signals i.sub.αobs, i.sub.βobs.

An alternating current power tool includes a brushless motor, a power module, a voltage conversion module, a drive circuit, and a controller. The power module is configured to receive an alternating current to supply power to the stator winding. The voltage conversion module is configured to receive the alternating current received by the power module and operatively output a direct current bus voltage. The drive circuit is electrically connected to the voltage conversion module and configured to drive the brushless motor. The controller is configured to start timing when the alternating current received by the power module crosses through a point of zero. In a preset time interval [T1, T2] of each half cycle, a first control signal is outputted to the drive circuit to power on the stator winding.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.