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 that is greater than 1200 continuous hot Watts out 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 volume of the power tool measured in cubic centimeters (cc), is greater than 600 Wout/Vain/cc.

A control unit calculates a motor voltage vector including a corresponding excitation voltage command and a torque voltage command in response to an output request for the motor and changes a first inverter voltage vector and a second inverter voltage vector while maintaining the motor voltage vector obtained to allow distribution of the motor voltage vector at any ratio. The first inverter voltage vector includes a first excitation voltage command and a first torque voltage command associated with an output from the first inverter, and the second inverter voltage vector includes a second excitation voltage command and a second torque voltage command associated with an output from the second inverter.

A vehicle driving apparatus includes an inverter which drives a permanent magnet motor. The inverter includes a three-phase bridge circuit including a plurality of switch elements, a drive circuit connected to the three-phase bridge circuit, a control circuit connected to the drive circuit, and an abnormality detecting unit which detects abnormality of the inverter. The drive circuit includes a three-phase-short-circuit-forming circuit which causes three phases of the permanent magnet motor to form short circuits, an abnormality accepting terminal which accepts an abnormality signal output from the abnormality detecting unit, and a check terminal which accepts an active check signal for causing the three-phase-short-circuit-forming circuit to perform three-phase short circuit control.

A motor driving circuit includes a rotation speed request generator, a motor driving signal generating unit, an inverter circuit, a position detecting circuit, a current detecting module, a rotation speed signal lookup module, an automatic leading angle controller, and a modulation signal generating circuit. When the rotation speed request signal indicates that a rotation speed of a motor is adjusted to a current rotation speed, the rotation speed signal lookup module queries a lookup table and generates a leading angle indication signal for indicating a current leading angle as a adjusting angle, and the automatic leading angle controller generates a phase adjusting signal, and the modulation signal generation circuit roughly adjusts a modulation waveform with the adjusting phase. The modulation signal generating circuit performs a fine adjustment on the modulation waveforms according to a phase difference, thereby making the current zero-crossing point near the BEMF zero point.

A conversion circuit board, including: a microprocessor module; a power module; a communication module; a first interface module; and a second interface module. The microprocessor module is adapted to communicate with a motherboard of an air conditioner via the communication module. The microprocessor module is adapted to connect to a first brushless direct current motor and a second brushless direct current motor via the first interface module and the second interface module, respectively. The power module supplies powers for the microprocessor module, the communication module, the first interface module, and the second interface module.

A backpack-type blower according to one aspect of the present disclosure includes a plurality of fans, a plurality of DC power supplies and a backpack. The plurality of fans and the plurality of DC power supplies are mounted on the backpack. The backpack-type blower is configured to blow winds from the plurality of fans together.

A driving device includes a connection switching unit that switches connection condition of a coil between Y connection and delta connection, an inverter, and a control device that controls a carrier frequency of the inverter. The carrier frequency is set at a first carrier frequency when the connection condition of the coil is the Y connection. The carrier frequency is set at a second carrier frequency when the connection condition of the coil is the delta connection.

A motor driving circuit includes a rotation speed request generator, a motor driving signal generating unit, an inverter circuit, a position detecting circuit, a current detecting module, a rotation speed signal lookup module, an automatic leading angle controller, and a modulation signal generating circuit. When the rotation speed request signal indicates that a rotation speed of a motor is adjusted to a current rotation speed, the rotation speed signal lookup module queries a lookup table and generates a leading angle indication signal for indicating a current leading angle as a adjusting angle, and the automatic leading angle controller generates a phase adjusting signal, and the modulation signal generation circuit roughly adjusts a modulation waveform with the adjusting phase. The modulation signal generating circuit performs a fine adjustment on the modulation waveforms according to a phase difference, thereby making the current zero-crossing point near the BEMF zero point.

A motor system provided with one motor and two inverters includes a first inverter control unit which changes a frequency of a first carrier wave (first carrier frequency) used for producing a switching signal fora first inverter according to an operating point of the motor; and a second inverter control unit which changes a frequency of a second carrier wave (second carrier frequency) used for producing a switching signal for a second inverter according to an operating point of the motor. The first carrier frequency has a changing characteristic depending on the first inverter control unit and the second carrier frequency has a changing characteristic depending on the second inverter control unit, and the changing characteristics are different from each other to make the first carrier frequency and the second carrier frequency differ from each other at an identical operating point.

A multi-motor system includes motor assemblies, each including a motor, a communication circuit to receive a command transmitted from outside, a control circuit to generate a control signal that rotates the motor with a controlled variable that is designated by the command; and a motor driving circuit that causes a current to flow in the motor based on the control signal. The command includes control data indicating the controlled variable of the motor in fixed data length, the controlled variable being expressed at least with an integer, and position-designating data designating a position of the radix point in the control data. The position-designating data is independently determined for each motor assembly.