A BLDC motor driver circuit includes: a driving power stage circuit configured to provide a start-up test signal in a start-up mode to excite a BLDC motor, to drive a rotor of the BLDC motor to rotate for a test; a current unidirectional circuit coupled to the BLDC motor at a reverse end for detecting a BEMF, to generate a detection signal at a forward end of the current unidirectional circuit, wherein when a voltage at the reverse end exceeds a voltage at the forward end, the current unidirectional circuit limits the voltage at the forward end not to be higher than a clamp voltage; a biasing circuit for biasing the current unidirectional circuit in a forward operation state and for providing the clamp voltage; and a sensor circuit for generating a sensing signal according to the detection signal to indicate a test rotation state of the BLDC motor.

A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L≥5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2≤i≤L) and an i−1st time is 180−360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180−360/L degrees or more and 180+360/L degrees or less.

A power conversion apparatus includes circuitry to: generate a first command to provide a first electrical output to a motor; receive a first electrical response to the first electrical output; estimate a position of a magnetic pole of the motor based on the first electrical response; set a pulse provide condition in accordance with the estimated position of the magnetic pole; generate a second command to provide a positive electrical pulse output and a negative electrical pulse output to the motor in accordance with the pulse provide condition; receive a positive electrical response to the positive electrical pulse output and a negative electrical response to the negative electrical pulse output; calculate a magnitude difference between the positive electrical response and the negative electrical response; change the pulse provide condition to generate a modified second command when the magnitude difference is smaller than a predetermined difference level; and estimate a polarity of the magnetic pole based on the magnitude difference corresponding to the modified second command when the magnitude difference is larger than the predetermined difference level.

In a motor control device that controls a sensorless-type motor, a controller estimates an initial magnetic pole position of a rotor of a motor by an inductive sensing scheme while sequentially setting a plurality of energization angles. At each of the set energization angles, the controller converts peak values of currents flowing through a plurality of phases of a stator winding into a first current component having an electrical angle that is equal to a corresponding one of the set energization angles and a second current component that is different in electrical angle by 90 degrees from the first current component, to correct the first current component based on the second current component. The controller estimates the initial magnetic pole position of the rotor based on the corrected first current component that is obtained at each of the set energization angles.

A power tool is provided including a brushless motor having a stator defining a plurality of phases, a rotor rotatable relative to the stator, and power terminals electrically connected to the phases of the motor. A power unit is provided including power switches. A control unit is interfaced with the power unit to output a drive signal to one or more of the motor switches to drive the phases of the motor over a series of sectors of the rotor rotation. The control unit is configured detect incorrect rotation of the rotor by applying a first series of voltage pulses to a present sector and a second series of voltage pulses to a previous sector, measuring motor currents associated with the first and second series of voltage pulses, and comparing corresponding motor current measurements to detect a transition from the present sector to the previous sector.

In a motor control device in one embodiment, an initial position estimation unit estimates an initial position of a magnetic pole of a rotor of a motor in an inductive sensing scheme. At each of energization angles, the initial position estimation unit multiplies a γ-axis current component Iγ corresponding to a peak value of a current flowing through a stator winding by each of a cosine value and a sine value of a correction angle obtained by correcting each of the energization angles. The initial position estimation unit estimates the initial position of the magnetic pole of the rotor based on a ratio between an integrated value of a multiplication result about the cosine value and an integrated value of a multiplication result about the sine value.

A brushless electrical machine, in particular, a brushless d.c. motor, having a housing, at least one rotor, which is positioned on a shaft rotationally mounted in the housing, and a stator attached to the housing; the rotor being assigned a rotor position detection device, which operates contactlessly and includes a multipole magnetic ring positioned on the shaft in a rotatably fixed manner and at least one sensor, which is sensitive to magnetic fields and is attached to the housing radially with respect to the outer circumference of the magnetic ring. The number of pole pairs of the rotor and the number of pole pairs of the magnetic ring are coprime.

Disclosed is a motor control apparatus, a motor control system, and a motor control method that estimate a stator resistance and a rotor position for sensorless control of a motor.

A method for controlling switched reluctance machine (SRM) utilizing a SRM control system. The method allows for adaptive pulse positioning over a wide range of speeds and loads. An initial rotor position is provided for the SRM utilizing an initialization mechanism. A pinned point on a phase current waveform is defined during an initial current rise phase of the current waveform. A slope of the current rise is determined as the current waveform reaches the pinned point. The slope is then fed to the commutation module of the SRM control system. An error signal from calculated inductance or current slope is used as an input to a control loop in the SRM control system. The time determining module determines an optimum time signal to fire a next pulse. The optimum time signal is fed to the SRM for turning the plurality of SRM switches to on and off states.

A motor controller integrated circuit (IC) includes a storage device containing software, and a processor core. The processor core has an output adapted to be coupled to a motor. The processor core is configured to execute the software to operate the motor in an open-loop control, calculate first and second orthogonal components of a back electromotive force (BEMF), calculate a total BEMF value, and determine that the first orthogonal component is within a threshold of the total BEMF value. The processor core is further configured to, responsive to the first orthogonal component being within the threshold of the total BEMF value, operate the motor in a closed-loop control.