PWM control of first and second inverters that control a double-winding type rotating electric machine is performed with mode switching between asynchronous PWM and synchronous PWM. A first-group triangular wave used for the PWM control of the first inverter is switched from the asynchronous PWM to the synchronous PWM in first timing at which carrier phases of an asynchronous PWM triangular wave and a synchronous triangular wave are matched with each other. A second-group of triangular wave used for the PWM control of the second inverter is switched from the asynchronous PWM to the synchronous PWM in second timing at which the carrier phases of the asynchronous PWM triangular wave and the synchronous triangular wave are matched with each other.

A motor control apparatus includes an inverter comprising switching elements, current detection means for detecting a phase current value output from the inverter to each phase of a three-phase AC motor, conversion means for converting the phase current value into a digital AD conversion value, and modulation means for comparing a phase voltage command value based on the AD conversion value from the conversion means with a PWM counter value generated using a timer operating at predetermined cycles to generate a PWM signal and outputting the generated PWM signal to the inverter to thereby switch the switching elements of the inverter and control the three-phase AC motor. The conversion means outputs the AD conversion value acquired by converting the phase current value at a timing when a rectangular width of a rectangular wave of a phase voltage value corresponding to the PWM counter value is long.

A motor drive control device causes a single phase motor including a coil of a first system and a coil of a second system to be driven. The motor drive control device has a first driving circuit configured to perform control to energize the coil of the first system, a second driving circuit configured to perform control to energize the coil of the second system, and a driving control unit configured to control an operation of the first driving circuit and an operation of the second driving circuit. The driving control unit has a driving voltage detecting unit configured to detect a driving voltage applied to the first driving circuit and a driving voltage applied to the second driving circuit, and a compensation control unit configured to cause one driving circuit between the first driving circuit and the second driving circuit to execute a maintenance operation for maintaining rotation of the single phase motor, based on a detection result of the driving voltage detecting unit.

A controller of an electrically powered vehicle includes an electronic control unit. The electronic control unit performs a switching control by a square wave control in a first switching mode when a rotation speed of the motor is equal to or higher than a first predetermined rotation speed. The electronic control unit performs the switching control by the square wave control in a second switching mode when the rotation speed of the motor is lower than the first predetermined rotation speed. The first predetermined rotation speed is a rotation speed lower than a first resonance region. The first switching mode is a mode of a switching pattern that suppresses LC resonance in the first resonance region. The second switching mode is a mode of a switching pattern that suppresses LC resonance in a second resonance region lower than the first predetermined rotation speed.

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.

A method and system to convert a constant speed motor drive (40) into a variable speed motor drive (80) are disclosed. The method comprises disconnecting a second terminal (68) from a first terminal (54) by removing from the constant speed motor drive (40) a first cover assembly (46) comprising the second terminal (68), the constant speed motor drive (40) comprising the first cover assembly (46) and a base assembly (42) including the first terminal (54), the cover assembly further comprising a constant speed controller (66), the first terminal (54) adapted to receive an alternating-current (AC) voltage and including motor contacts operable to output a motor voltage, wherein the constant speed controller (66) generates the motor voltage for the motor contacts when the constant speed controller (66) operates; and connecting a third terminal (68) to the first terminal (54) by coupling a second cover assembly (82) to the base assembly (42), the second cover assembly (82) comprising the third terminal (68) and a variable speed controller (100) electrically coupled to the third terminal (68).

A motor drive device is proposed. The motor drive device is configured to drive a motor having a plurality of windings respectively corresponding to a plurality of phases, and includes: a first inverter including a plurality of first switching elements, and connected to a first end of each of the plurality of windings; a second inverter including a plurality of second switching elements, and connected to a second end of each of the plurality of windings; and a controller configured to generate phase voltage commands of the first inverter and phase voltage commands of the second inverter based on preset voltage commands of the motor so that the phase voltage commands of the first inverter and the phase voltage commands of the second inverter are respectively represented as vectors of different angles.

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.

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.0maxn, where n is a fixed value in the range of 0.3(f.sub.0maxf.sub.0min) to 0.8(f.sub.0maxf.sub.0min). Therefore, the appliance has a higher mechanical efficiency, a simple structure and a lower cost.