A power tool is provided including: an electric brushless direct current (BLDC) motor having rotor and a stator defining phases; a power unit including a first switch circuit connected electrically between a first power supply and the motor, and a second switch circuit connected electrically between a second power supply and the motor; and a controller configured to control a switching operation of the first switch circuit and the second switch circuit to regulate a supply of power from at least one of the first power supply and/or the second power supply to the motor.

The technologies described and recited herein pertain to a permanent magnet motor having multiple voltage taps so that the motor may run in multiple configurations, e.g., a low-range and a high-range, and have multiple optimal operating points.

A wall-mountable load control device may include an illuminated rotary knob for providing a nightlight feature. The load control device may be configured to control an intensity of a lighting load. The load control device may include a yoke adapted to be mounted to an electrical wall box, an enclosure attached to the yoke, a faceplate attached to the yoke and having an opening, a mounting member attached to the yoke, and/or a potentiometer located within the enclosure and having a shaft extending through an opening in the yoke and the opening of the faceplate. The load control device may include a collar attached to the boss of the mounting member and surrounding the shaft of the potentiometer. The mounting member may be configured to conduct light from at least one light source housed within the enclosure to illuminate the faceplate.

A driving device drives a motor including a rotor having a neodymium rare earth magnet. The driving device includes an inverter, a first detector that outputs a first detection signal corresponding to a motor driving current supplied to the motor, a protection level setting unit that sets an overcurrent protection level, a second detector that outputs a second detection signal corresponding to a driving state of the motor, and a control device. The control device executes first control of lowering the motor driving current immediately after the motor driving current corresponding to the first detection signal exceeds the overcurrent protection level. When the protection level setting unit lowers the overcurrent protection level to a new current level based on the second detection signal, the control device executes second control of lowering the motor driving current to a level lower than the new current level.

Techniques and methods related to a multi-mode operation of a synchronous electrical generator. The synchronous generator is configurable in at least two modes: a grid-power mode and a power-generation mode. In the power-generation mode, electrical power is generated in response to power produced by a prime mover. In the grid-power mode, the rotor is in standstill mode, and the configurable rotor winding is configured to generate a plurality of AC magnetic fields. The system provides for seamless transfer of power between grid-power to power generation using an energy storage unit and associated power conditioning apparatus.

A motor-driving apparatus for driving a motor having a plurality of windings respectively corresponding to a plurality of phases is provided. The motor-driving apparatus includes a first inverter having a plurality of first switching devices and connected to first ends of the plurality of windings and a second inverter having a plurality of second switching devices and connected to second ends of the plurality of windings. A third switching device is configured to selectively connect and disconnect points at which a number of turns of each of the windings is divided in a preset ratio. A controller is configured to adjust an on/off state of the first to third switching devices based on required output of the motor.

A motor drive apparatus includes a connection switching device that switches a connection state of windings of a first motor by switches; an inverter that applies an alternating-current voltage to the windings; a first control device that controls the inverter and the connection switching device; and a second control device that controls a second motor for an element that affects the first motor. Control by the first control device when switching includes a first stage of bringing an effective value of alternating current flowing through the windings close to zero compared to that before the connection state is switched; and a second stage of suspending output of the alternating-current voltage from the inverter. The second control device keeps the second motor running during the first and second stages, and the first control device switches the switches in the second stage.

An electric drive unit for a hybrid drive, in particular for a vehicle, has an increased power output and degree of efficiency, while thermal loading as well as required installation space and manufacturing costs are minimized. The electric drive unit has an asynchronous machine with a rotor with a rotor cage, in particular a rotor cage which is formed with copper conductors. The asynchronous machine is formed with a stator having a shaft winding. The shaft winding is formed with a device for star-delta changeover. The rotor is formed with a rotor internal cooling device. A step-up gear mechanism is arranged in a power train between the rotor and the output element. There is also described a hybrid drive device with an electric drive unit, and a vehicle that has an electric drive unit and/or a hybrid drive device.

An engine generator, including a general purpose engine, an engine speed of the engine being variably controlled, a generator unit having a three-phase winding and driven by the engine to generate power, an inverter unit converting AC output from the generator unit to AC of a predetermined frequency to output to a load, a connection switching unit switching a connection configuration of the winding to one of a wye-connection and a delta-connection, a load detection unit detecting a size of the load, and a connection switching control unit controlling the connection switching unit to switch the connection configuration to the wye-connection when the size of the load is equal to or lower than a predetermined value, and to switch the connection configuration to the delta-connection when the size of the load is higher than the predetermined value.

A motor-driving apparatus for driving a motor having a plurality of windings respectively corresponding to a plurality of phases is provided. The motor-driving apparatus includes a first inverter having a plurality of first switching devices and connected to first ends of the plurality of windings and a second inverter having a plurality of second switching devices and connected to second ends of the plurality of windings. A third switching device is configured to selectively connect and disconnect points at which a number of turns of each of the windings is divided in a preset ratio. A controller is configured to adjust an on/off state of the first to third switching devices based on required output of the motor.