A power tool includes a brushless motor including several windings, a drive circuit for driving the brushless motor, a detection device for detecting the brushless motor so as to obtain a load parameter corresponding to a load of the brushless motor, and a controller for outputting a first control signal to reduce current of the brushless motor in a first slope when the load parameter exceeds a first preset range.

A device for driving a plurality of motors, including an inverter connected to a DC terminal; a multi-phase motor connected to the inverter; and a single-phase motor serially connected to the multi-phase motor, wherein a number of frequency of current input to the multi-phase motor when driving the single-phase motor and the multi-phase motor at the same speed is smaller than the number of frequency of current input to the multi-phase motor when driving the single-phase motor and the multi-phase motor at different speeds. Accordingly, a plurality of motors can be simultaneously driven at different speeds, by using a single inverter.

An AC electric motor drive system includes a power supply transformer connected to an AC power supply and insulating an AC power supply side and a load side; an AC electric motor; a power converter which converts AC voltage outputted from the power supply transformer to output AC voltage, and which outputs the output AC voltage to the AC electric motor; and a capacitive component having one end connected to the load side of the power supply transformer, and another end grounded.

A motor driving device controls a three-phase motor and a single-phase motor to operate in parallel. The motor driving device includes a dc terminal in which an upper and a lower DC-link capacitor are located. The motor driving device also includes a neutral terminal disposed between the upper and lower DC-link capacitors. The motor driving device includes an inverter that includes three pairs of upper switching elements and lower switching elements. Two pairs of upper switching elements and lower switching elements among three pairs are connected to an a-phase terminal and a b-phase terminal of the three-phase motor, respectively. The other pair of upper switching elements and lower switching elements among three pairs is connected to a first terminal of the single-phase motor. The neutral terminal is connected to a second terminal of the single-phase motor. A c-phase terminal of the three-phase motor is connected to the single-phase motor.

A motor including: a stator including plural windings that form coils and are connected together at a neutral point; a switching circuit that generates a rotating magnetic field around the stator by switching of a power supply to the plurality of windings; a rotor that rotates in response to the rotating magnetic field generated around the stator; a resistor for current detection that detects a current in the switching circuit and that is disposed between the switching circuit and a grounding point; and a filter element that reduces a fluctuation in potential at the neutral point, the filter element being disposed between the neutral point and the resistor for current detection and being grounded at the grounding point via the resistor for current detection.

A power conversion device for charging a battery of a vehicle may include the battery, a motor for receiving a battery power source from the battery, a power controller for controlling the motor to change the battery power source into charging power, and a charging controller for selectively performing a charging power supply control for supplying the charging power to the outside and a charging power receipt control for receiving external power.

An inverter controller is configured to control an inverter circuit that drives an on-vehicle electric motor by using an on-vehicle electricity storage device. The inverter controller includes a two-phase voltage command value deriving unit that derives two-phase voltage command values on the basis of an external command value delivered from an external device and an acquisition result of a speed acquiring unit, and a three-phase voltage command value deriving unit that derives three-phase voltage command values on the basis of the two-phase voltage command values. The three-phase voltage command value deriving unit derives the three-phase voltage command values on the basis of a voltage utilization factor, which is calculated on the basis of the two-phase voltage command values and the acquisition result.

A rotating electric machine drive system includes: a rotating electric machine equipped with: a rotor having one magnetic pole configured by permanent magnets, and a salient pole portion that is magnetically convex in a radial direction; and a stator wound with a multiphase stator winding; an inverter for supplying electric power to the stator winding; and a control unit for controlling energization current of the inverters. The control unit performs energization control of the stator winding such that a fundamental wave current at a fundamental frequency synchronized with a rotational speed of the rotor, and a harmonic current that is triple the fundamental frequency flow in the stator winding, and such that energization of the harmonic current generates a stator magnetic field having a specified lead phase or delay phase with respect to a third-order magnetic field of the rotor.

A motor driving device controls a three-phase motor and a single-phase motor to operate in parallel. The motor driving device includes a dc terminal in which an upper and a lower DC-link capacitor are located. The motor driving device also includes a neutral terminal disposed between the upper and lower DC-link capacitors. The motor driving device includes an inverter that includes three pairs of upper switching elements and lower switching elements. Two pairs of upper switching elements and lower switching elements among three pairs are connected to a-phase terminal and b-phase terminal of the three-phase motor, respectively. The other pair of upper switching elements and lower switching elements among three pairs is connected to a first terminal of the single-phase motor. The neutral terminal is connected to c-phase terminal of the three-phase motor and a second terminal of the single-phase motor.

A power conversion apparatus for multi-voltage charging is provided. The power conversion apparatus includes a housing, a motor connecting terminal disposed at one side of the housing, a relay having a first end electrically connected to the motor connecting terminal, and a capacitor having a first terminal electrically connected to a second end of the relay, and second and third terminals respectively connected to positive and negative terminals of an external battery, wherein the motor connecting terminal, the relay, and the first, second and third terminals are disposed within the housing along an outer edge of the housing.