A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. The controller detects an initial sector within which the rotor is located at start-up, apply the drive signal so as to rotate the motor to a parking angle associated with the detected initial sector, and control a commutation sequence to drive the motor beginning at the parking angle.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. If the supply of power to the motor is turned OFF to cause the motor to slow down and is turned back ON while the rotor speed exceeds a speed threshold, the controller electronically brakes the motor for a time interval to measure the phase current of the motor and detects the angular position of the rotor based on the measured phase current.

The present invention addresses the problem of providing a method for detecting magnetic field location which can realize low cost by using simple hardware and software and can detect a rotor location in units of excitation sections in 120-energization without generating sensing noise at the time of initiation. As a solution, an MPU (51) obtains, through calculation, a neutral point potential from an energization-phase voltage measured by an A/D conversion circuit (53), obtains the difference between the neutral point potential and a non-energization-phase voltage, performs magnitude comparison between the difference and a negative-side threshold value in the case where the present location is an odd-numbered section or between the difference and a positive-side threshold value in the case where the present location is an even-numbered section, and determines the end point of the 60-energization section when the difference exceeds a threshold value in a direction away from the neutral point potential.

Provided is a motor control device having a function for determining a rotor position of a synchronous motor, without use of a sensor, the device prevents obtaining an erroneous rotor position, to enable stable control of the synchronous motor based on the rotor position in both the normal-control region and the flux-weakening-control region. The motor control device 1 includes: a first rotor position determining unit 19 that determines a rotor position of the synchronous motor 2 based on an induced voltage electrical angle, and a first induced voltage phase obtained from a current peak value and a difference between the induced voltage electrical angle and a current electrical angle; a second rotor position determining unit 20 that determines a rotor position of the synchronous motor 2 based on an induced voltage electrical angle, and a second induced voltage phase obtained from a flux linkage and a current peak value; and a selecting unit 21 that selects the first rotor position determining unit 19 or the second rotor position determining unit 20, based on a current peak value, and a first induced voltage phase or a second induced voltage phase.

An inverter control apparatus and a motor drive system includes an inverter main circuit that drives a synchronous motor; an electric-current detector that detects an electric current flowing between the inverter main circuit and the synchronous motor; a command generator that generates an electric-current command value of an output electric current that is output from the inverter main circuit to the synchronous motor, in accordance with a torque command that is supplied externally; and an electric-current controller that generates a voltage command value for the inverter main circuit so that the electric-current command value and a detected electric-current value detected in the electric-current detector are equal to each other. The command generator generates the electric-current command value so that a fundamental wave current that is equal to or greater than a threshold is supplied to the synchronous motor, in driving the inverter main circuit.

A machine tool includes three mutually independent data transmission mechanisms. The data transmission mechanisms include respective transmission units which assign codes for detecting errors to data acquired from the output of sensors, and which transmit the data. A machine controller includes an operation judgment unit which judges whether operation of a feed axis motor is continued. The operation judgment unit judges that operation is continued when there are two pieces of data for which a relationship between the data and the code matches a rule, and the two pieces of data are within a predetermined judgment range. The operation judgment unit judges that the feed axis motor is stopped when at least one of the pieces of data for which the relationship matches the rule deviates from the judgment range.

An adjusting unit of an internal combustion engine is provided, comprising an electric motor and a transmission interacting therewith, an adjusting shaft of the transmission being coupled to the rotor of the electric motor. A drive shafts of the transmission coupled to the shaft which is to be adjusted. For controlling the electric motor, a sensorless control unit is provided outside of a housing of the electric motor which encloses the stator of the electric motor.

A circuit includes a processor that analyzes a pulse width modulated (PWM) signal feedback from a brushless DC motor to determine a transition between a mutual inductance zero crossing condition and a Back Electro Motive Force (BEMF) zero crossing condition of the brushless DC motor. A mutual inductance controller is executed by the processor to commutate the brushless DC motor at startup of the motor when the mutual inductance zero crossing condition is detected by the processor. A BEMF controller is executed by the processor to commutate the brushless DC motor after startup of the motor when the BEMF zero crossing condition is detected by the processor.

Disclosed is a sensorless control system for a permanent magnet synchronous machine. The sensorless control system includes a counter electromotive force estimation unit configured to estimate a counter electromotive force using a phase voltage reference applied to an inverter and a phase current applied from the inverter to the permanent magnet synchronous machine, and a speed estimation unit configured to estimate an angular velocity and an electrical angle of a rotor of the permanent magnet synchronous machine, and the counter electromotive force estimation unit according to one embodiment of the present disclosure may maintain robust performance at a low speed by modifying some portion of a conventional Luenberger observer.

A control system for an electrical motor comprises a rotor, a stator having a plurality of phase windings, and an inverter for applying voltage to the plurality of phase windings by connecting individual phase windings to a first or second voltage level. The control system is configured to measure a first rate of change of current in a first phase winding, of said plurality of phase windings, connected to the first voltage level, to measure a second rate of change of current in a second, different phase winding connected to the first voltage level, and to calculate a difference between the first and second rate of change of current. The control system is further configured to use the calculated difference to obtain data related to a position of the rotor.