An electric power tool includes: a brushless motor having a plurality of stator windings and configured to rotate in accordance with voltages applied to the plurality of stator windings, an induced voltage being generated in accordance with a rotation of the brushless motor; a rectifier circuit configured to rectify an AC voltage; a smoothing capacitor configured to smooth the AC voltage rectified by the rectifier circuit to a pulsation voltage having a maximum value larger than the induced voltage and a minimum value smaller than the induced voltage; and an inverter circuit configured to perform switching operations to output the pulsation voltage to the plurality of stator windings by rotation.

Electric power tool

A motor driving apparatus comprises an inverter circuit for converting an output voltage of a power supply into a three-phase AC and outputting the same to the brushless motor; a rotor position estimation unit for estimating a rotor position of the brushless motor; and an inverter control unit for controlling the inverter circuit so that the brushless motor is driven by a current based on the estimated rotor position. The inverter control unit determines an advance angle of the current supplied to the brushless motor with respect to the estimated rotor position so as to minimize a deviation between a command rpm and an actual rpm. Therefore, it is possible to perform stable weak field control for the brushless motor, independently from the input voltage of the inverter circuit, without using predetermined control variables such as table values.

Motor driving apparatus

A power conversion device includes a power switching circuit that supplies AC voltages generated between switching elements operating as upper arms and switching elements operating as lower arms, and a control circuit that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements by a PWM method in a first operational region in which frequency of an AC power to be outputted is low, and that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements at timings based upon the phase of the AC power to be outputted in an operational region in which the frequency of the AC power to be outputted is higher than in the first operational region.

Power Conversion Device

A method of controlling a brushless motor, the method comprising exciting a winding of the motor for a conduction period over each electrical half-cycle of the motor. The length of the conduction period is defined by a waveform that varies periodically with time. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Control of a brushless motor

An inverter controlling device for controlling an inverter so that the capacitor current may be decreased and the distortion of the power supply current may be decreased, comprising a conventional capacitorless inverter control block (11), an I1 calculating block (12) for receiving a motor torque τm, a motor rotational speed ωm, a power supply voltage V1, and a factor η, performing calculation of equation (10) to determine a power supply current i1, and outputting the power supply current i1 as a power supply current command variable i1a, a feedback calculating block (13) for receiving the power supply current command variable i1a and a real current i1 and outputting a torque command for correction or a torque current command for correction after performing calculation (e.g., PI calculation) so that the difference between the power supply current command variable i1a and the real current i1 may be zero, and a subtraction block (14) for subtracting the torque command for correction or the torque current command for correction from a tentative torque command or a tentative torque current command outputted from the conventional capacitorless inverter control block (11) so as to generate a final torque command or a final toque current command.

Inverter control method and its device

PROBLEM TO BE SOLVED: To provide a controller for a motor which does not much affect efficiency even if ripple occurs sharply, and an inverter for drive of the motor, which controls the currents of the d and q axes of the motor so that the the input current i may become sine waves as far as possible by letting a current ed contain ripple intentionally and controlling it. SOLUTION: This controller for an inverter for drive of a motor improves the input power factor of a diode full wave rectifying circuit 2 and the waveform, by controlling the torque of a motor 5 in advance, with the frequency double the power source, by means of a single-phase diode full wave rectifying circuit 2 which receives the input of a single-phase AC power source 1, a small- capacity smoothing capacitor 3 about one hundredth the smoothing capacitor for a conventional diode full wave rectifying circuit connected to this, and 8 control circuit 6 composed of a PWM inverter circuit 4 for control and a motor 5.

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Papers

Controller for inverter for drive of motor

勲 高橋

Papers

Controller for inverter for drive of motor

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