Provided is an electronic timepiece capable of suppressing variation in the drive speed of a rotor, and driving a motor at a constant speed. The electronic timepiece has a driver; a controller that controls the driver to the on state or the off state according to a current flowing through a coil of a motor; a detection signal output device configured to output a detection signal when the on time or the off time, which are the continuous time of the on state and off state of the driver, meets a specific condition; a reference signal output device that outputs a reference signal used as a reference of a drive speed of the motor; and a drive cycle adjuster that compares the output timing of the detection signal and the reference signal, shortens the drive cycle when the detection signal is output after the reference signal, and when the detection signal is output before the reference signal, lengthens the drive cycle of the motor.

A power tool comprising a housing and a brushless direct-current (BLDC) motor disposed within the housing. The motor includes a stator and a rotor rotatable relative to the stator. The power tool is configured to generate a power output from the motor such that a quotient obtained by the power output measured in Watts (Wout), divided by an input measured in Volt-Amperes (Vain), and further divided by a diameter of the motor measured in meters (m), is greater than 10 Wout/Vain/m.

A rotary electric machine control device for controlling driving of a rotary electric machine including a plurality of winding sets, includes: a plurality of drive circuits; and a plurality of control units, each of which includes: an individual current limit value calculation unit; a current limit value calculation unit; and a control signal calculation unit. The current limit value calculation unit switches between a current limit value sharing mode and a current limit value non-sharing mode. An electric power steering device includes: the rotary electric machine control device; the rotary electric machine that outputs an assist torque for assisting a steering operation of a steering wheel by a driver; and a power transmission unit that transmits a driving force of the rotary electric machine to a drive target.

An inverter control device that controls a multiple of inverters configured to use the same positive and negative direct current voltage bus lines connected to a power supply and driving a corresponding multiple of motors, the inverter control device including smoothing control means that controls an inverter outflow current so that voltage of the power supply is smoothed by a smoothing capacitor connected to the positive and negative direct current voltage bus lines, and two-phase modulation operation means that fixes a predetermined one phase of a three-phase modulated wave at either a maximum voltage or minimum voltage the inverter can output determined by a voltage between the positive and negative direct current voltage bus lines, and calculates a modulated wave that causes the other two phases to switch.

A system, in one embodiment, includes a drive having a housing, a stator disposed in the housing, a rotor disposed in the stator, and a programmable logic controller disposed inside, mounted on, or in general proximity to the housing. In another embodiment, a system includes a network, a first motor having a first integral programmable logic controller coupled to the network, and a second motor having a second integral programmable logic controller coupled to the network. In a further embodiment, a system includes a rotary machine having a rotor and a stator disposed concentric with one another, a microprocessor, memory coupled to the microprocessor, a power supply coupled to the microprocessor and the memory, and a machine sensor coupled to the microprocessor.

A motor driving apparatus and a method of driving a plurality of permanent magnet synchronous motor (PMSM) using a single inverter is described. The motor driving apparatus includes a single power conversion apparatus configured to supply power to a plurality of motors and a control apparatus configured to control the power conversion apparatus to adjust a phase current ratio supplied to the plurality of motors from the single power conversion apparatus according to a requirement of each of the plurality of motors.

A motor control system includes: a converter; two inverters; two alternating-current motors; and a control unit. The control unit is configured to control the system voltage by feedback of a current phase of a current vector of motor current of each of the motors on a d-q coordinate plane so that rectangular wave control of at least one of the first and second motors is performed in a state where the current phase is an optimal current phase, wherein the control unit selects, as a subject of the feedback, the current phase of one of the motors that is larger than the other motor in system voltage deviation obtained based on the current vector.

A handheld AC power tool is provided. The power tool is comprised generally of: a brushless DC motor; a power cord connectable to an AC power socket; a converter circuit configured to receive input power from the power cord and operable to output a DC bus voltage, a switching arrangement interposed between the electric motor and the converter circuit; a motor drive circuit interfaced with the motor switches; and a power switch operable by a user to selectively energize the motor drive circuit and thereby power on the tool. The converter circuit includes a rectifier and a capacitor electrically coupled across the rectifier, such that the capacitor has capacitance sized to produce a DC bus voltage whose magnitude from an AC power source is substantially same as magnitude of voltage from a DC power source.

A method of controlling a plurality of permanent magnet synchronous motors using a single inverter that includes obtaining an estimate of rotor position and speed individually for a plurality of permanent magnet synchronous motors. The method can include calculating the average rotor position from the obtained estimate of the rotor position for each permanent magnet synchronous motor of the plurality of permanent magnet synchronous motors. The method can include reconstructing a rotor permanent-magnet flux for each permanent magnet synchronous motor and transforming the reconstructed rotor permanent-magnet flux for each permanent magnet synchronous motor to average fluxes and average differential fluxes on an average d-q reference frame. The method can include obtaining the average current reference in the average d-q reference frame for the plurality of permanent magnet synchronous motors; and determining an inverter voltage reference.

A control unit distributes a motor voltage vector corresponding to an output request for a motor to a first and a second inverter voltage vectors associated with outputs from a first inverter and a second inverter, and determines whether a switching condition for three-phase-on mode is satisfied. Determining that the switching condition is satisfied, the control unit switches to three-phase-on mode in which every high-side switching element or every low-side switching element of one inverter is turned on and one end of a coil in each phase of the motor is brought into common connection, and the control unit drives the motor with an output from the other inverter. Herein, the switching condition for three-phase-on mode includes failure of one inverter and an inverter voltage vector of an output from one inverter being approximate to 0 when neither of the inverters fails.