The invention relates an electrical cleaning and care appliance, pressure alarming method and apparatus for the appliance. Transducer elastic members of the appliance engage in resonance oscillation motion with bending strain characteristics, are symmetrically distributed on the left and right sides of the longitudinal axis (L.sub.2) of a drive shaft, and have approximately equal section moduli in bending, approximately equal lengths, approximately equal deflection amplitudes and opposite flexure directions; the angle between the longitudinal axis (L.sub.1) of a cleaning element and the normal direction of the transducer elastic member plane is 0° to 60°; the frequency of the alternating current in a drive coil is a fixed value equal to f.sub.0max−n, where n is a fixed value in the range of −0.3(f.sub.0max−f.sub.0min) to 0.85(f.sub.0max−f.sub.0min). Therefore, the appliance has a higher mechanical efficiency, a simple structure and a lower cost.

A power conversion device includes a printed circuit board, whose mounting surface is opposite to an annular surface formed by an annular stator that constitutes a motor, arranged to be separated from the annular surface with a predetermined distance, and mounted with a Hall element that detects a rotation position of a rotor of the motor on a mounting surface on a side of the stator; an inverter IC that is mounted on the mounting surface on the side of the stator of the printed circuit board to supply a high-frequency current to the stator; and an overheat detection unit that is mounted on the mounting surface on the side of the stator of the printed circuit board and detects an overheated state of the inverter IC. When the overheat detection unit detects an overheated state, the inverter IC restricts or stops a current to be supplied to the stator.

In a motor drive device 120, a phase compensation amount calculation unit 110 calculates a phase compensation amount Δθ for compensating a voltage phase θv* when a control mode is switched in a control selection unit 90. The control selection unit 90 outputs the three-phase voltage command Vuvw* according to any one of the plurality of control modes based on the modulation factor Kh*, the voltage phase θv*, and the phase compensation amount Δθ. A PWM control unit 100 outputs gate signals Gun, Gup, Gvn, Gvp, Gwn, and Gwv based on the three-phase voltage command Vuvw* and a rotor position θd. The inverter 20 has a plurality of switching elements, and controls the plurality of switching elements based on gate signals Gun, Gup, Gvn, Gyp, Gwn, and Gwv to drive the AC motor 10.

A turboelectric distributed propulsion based on brushless doubly-fed machines (BDFMs) is provided, which minimizes power conversion, enhances mechanical reliability, and strengthens fault-tolerance capability of a DC-based propulsion system. A turboelectric distributed propulsion (TeDP) architecture using BDFMs for aviation applications, and a designed BDFM, inverter, and controller are provided. Simulations and systems are also provided.

A motor driving system includes first and second motors including multiple first windings and second windings; a first inverter including a DC terminal connected to a DC voltage source and an AC terminal connected to the multiple first windings; a first switch part including a plurality of first mode change switches connected to the multiple first windings; a second inverter including a DC terminal connected to the DC voltage source and an AC terminal connected to the plurality of first mode change switches; a second switch part including a plurality of second mode change switches connected to the AC terminal of the second inverter and the multiple second windings; a third switch part including a plurality of third mode change switches connected to the multiple first windings; and a controller configured to control the short-circuited state or the open state of the multiple first mode, second and third mode change switches, based on whether the first and the second motors are driven.

Embodiments of the disclosure provide a comb drive, a comb drive system, and a method of operating the comb drive to rotate bi-directionally in a MEMS environment. An exemplary comb drive system may include a comb drive, at least one power source, and a controller. The comb drive may include a stator comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The comb drive may also include a rotor comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The controller may be configured to apply first and second voltage levels having opposite polarities to the first and second electrically conductive layers of the rotor comb, respectively. The controller may also be configured to apply an intermediate voltage level to one of the first or second electrically conductive layers of the stator comb.

Embodiments of the disclosure provide a comb drive, a comb drive system, and a method of operating the comb drive to rotate bi-directionally in a MEMS environment. An exemplary comb drive system may include a comb drive, at least one power source, and a controller. The comb drive may include a stator comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The comb drive may also include a rotor comb having a first electrically conductive layer spaced apart from a second electrically conductive layer. The controller may be configured to apply first and second voltage levels having opposite polarities to the first and second electrically conductive layers of the rotor comb, respectively. The controller may also be configured to apply an intermediate voltage level to one of the first or second electrically conductive layers of the stator comb.

Methods and control apparatus for operating a three-phase electric motor are described, in which the motor windings are switched between Star and Delta connections depending on torque requirements, and in which the motor windings are switched to a braking mode when braking torque is required. The electromagnetic torque of the motor is monitored, and a command to switch from Star to Delta is given when the electromagnetic torque rises to reach or exceed a threshold.

Provided is a method of controlling a multi-channel multi-phase electrical machine including a plurality of channels each with a set of phase windings connected to a converter, which method includes the steps of operating the converters to electrically phase-shift the channels; computing harmonic injection currents for a dominant harmonic on the basis of electrical quantities in a rotating reference frame; determining harmonic voltage references for the dominant harmonic on the basis of the harmonic injection currents; and regulating the AC output voltages of the channels according to the fundamental voltage references and the harmonic voltage references. Also provided is a control arrangement of a multi-channel multi-phase electrical machine; a wind turbine; and a computer program product.

A motor controller comprises a switch circuit and a driving circuit. The switch circuit is coupled to a three-phase motor for driving the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. The motor controller utilizes a first pulse width modulation waveform and a second pulse width modulation waveform for driving the three-phase motor, where the first pulse width modulation waveform and the second pulse width modulation waveform have different frequencies from each other. The motor controller utilizes the second pulse width modulation waveform to detect a phase switching time point, where the frequency of the first pulse width modulation waveform is greater than the frequency of the second pulse width modulation waveform.