A circuit board comprising a first power terminal, a second power terminal spaced apart from the first power terminal, a first ground terminal, a second ground terminal spaced apart from the first ground terminal, a first magnetic element part disposed along a first circular arc having a first radius, and a second magnetic element part disposed along a second circular arc having a second radius greater than the first radius, wherein an angle of at least one portion of the first circular arc is not overlapped with an angle of the second circular arc.

A motor commutation waveform generating circuit is provided. The motor commutation waveform generating circuit includes: an edge detection circuit, configured to receive sensing signals of the motor and derive a clock signal indicating a commutation switching point of the motor; an angle cutting circuit, controlled by the clock signal to generate an angle indication pulse indicating a rotation angle of the motor; a synthetic wave generating circuit, using the angle indication pulse to sequentially change waveform voltages corresponding to required angles and output them in segments; and a signal combining circuit, controlled by the clock signal to combine waveform voltage signals generated by the synthetic wave generating circuit, thereby obtaining a plurality of synthetic waveforms provided to a drive control system of the motor for drive control after pulse width modulation.

A motor commutation waveform generating circuit is provided. The motor commutation waveform generating circuit includes: an edge detection circuit, configured to receive sensing signals of the motor and derive a clock signal indicating a commutation switching point of the motor; an angle cutting circuit, controlled by the clock signal to generate an angle indication pulse indicating a rotation angle of the motor; a synthetic wave generating circuit, using the angle indication pulse to sequentially change waveform voltages corresponding to required angles and output them in segments; and a signal combining circuit, controlled by the clock signal to combine waveform voltage signals generated by the synthetic wave generating circuit, thereby obtaining a plurality of synthetic waveforms provided to a drive control system of the motor for drive control after pulse width modulation.

The present invention provides an apparatus for sensing rotor location, the apparatus comprising: a central shaft; a magnet coupled to the central shaft; a sensor portion is disposed correspond to the magnet; wherein the sensor portion comprising a substrate, a first group including a first Hall sensor and a third Hall sensor disposed on the substrate, and a second group including a second Hall sensor and a fourth Hall sensor, the first Hall sensor and the third Hall sensor are arranged to overlap in a radial direction about the central shaft and the second Hall sensor and the fourth Hall sensor are arranged to overlap in a radial direction about the central shaft.

The present invention provides an apparatus for sensing rotor location, the apparatus comprising: a central shaft; a magnet coupled to the central shaft; a sensor portion is disposed correspond to the magnet; wherein the sensor portion comprising a substrate, a first group including a first Hall sensor and a third Hall sensor disposed on the substrate, and a second group including a second Hall sensor and a fourth Hall sensor, the first Hall sensor and the third Hall sensor are arranged to overlap in a radial direction about the central shaft and the second Hall sensor and the fourth Hall sensor are arranged to overlap in a radial direction about the central shaft.

A motor current controlling circuit having a voltage detection mechanism is provided. A first terminal of a first low-side transistor is connected to a second terminal of a first high-side transistor. A node between the first terminal of the first low-side transistor and the second terminal of the first high-side transistor is connected to a first terminal of a motor. A first terminal of a second low-side transistor is connected to a second terminal of a second high-side transistor. A zero current detector circuit detects a voltage of the node and determines whether or not a current flowing through the motor is equal to a zero value to output a zero current detected signal according to the detected voltage. A controller circuit controls a driver circuit to turn on or off the high-side transistors and the low-side transistors according to the zero current detected signal.

A motor current controlling circuit having a voltage detection mechanism is provided. A first terminal of a first low-side transistor is connected to a second terminal of a first high-side transistor. A node between the first terminal of the first low-side transistor and the second terminal of the first high-side transistor is connected to a first terminal of a motor. A first terminal of a second low-side transistor is connected to a second terminal of a second high-side transistor. A zero current detector circuit detects a voltage of the node and determines whether or not a current flowing through the motor is equal to a zero value to output a zero current detected signal according to the detected voltage. A controller circuit controls a driver circuit to turn on or off the high-side transistors and the low-side transistors according to the zero current detected signal.

The present disclosure provides a displacement detection circuit of a maglev rotor system and a displacement self-sensing system thereof. The displacement detection circuit comprises a current sampling circuit (10) configured to collect a current flowing through a corresponding coil (4); coils (4), which are coils (4) distributed in series in the maglev rotor system; Hall sensors (20), the Hall sensors (20) being arranged in an upper auxiliary air gap (8) and a lower auxiliary air gap (8) of the maglev rotor system, and sensing surfaces of the Hall sensors (20) being perpendicular to magnetic field directions in the corresponding auxiliary air gaps (8); a Hall signal processing circuit (30) connected to the Hall sensors (20) and configured to differentiate a Hall sensing signal corresponding to the upper auxiliary air gap (8) and a Hall sensing signal corresponding to the lower auxiliary air gap (8); and a displacement signal resolving circuit (40) connected to the current sampling circuit (10) and the Hall signal processing circuit (30) respectively and configured to acquire a displacement of a rotor in the maglev rotor system according to the current and a differentiation result. By using the detection circuit and the displacement self-sensing system thereof, the axial size of the rotor is reduced, such that detection and control are coplanar, and high precision and simple design are realized.

The present disclosure provides a displacement detection circuit of a maglev rotor system and a displacement self-sensing system thereof. The displacement detection circuit comprises a current sampling circuit (10) configured to collect a current flowing through a corresponding coil (4); coils (4), which are coils (4) distributed in series in the maglev rotor system; Hall sensors (20), the Hall sensors (20) being arranged in an upper auxiliary air gap (8) and a lower auxiliary air gap (8) of the maglev rotor system, and sensing surfaces of the Hall sensors (20) being perpendicular to magnetic field directions in the corresponding auxiliary air gaps (8); a Hall signal processing circuit (30) connected to the Hall sensors (20) and configured to differentiate a Hall sensing signal corresponding to the upper auxiliary air gap (8) and a Hall sensing signal corresponding to the lower auxiliary air gap (8); and a displacement signal resolving circuit (40) connected to the current sampling circuit (10) and the Hall signal processing circuit (30) respectively and configured to acquire a displacement of a rotor in the maglev rotor system according to the current and a differentiation result. By using the detection circuit and the displacement self-sensing system thereof, the axial size of the rotor is reduced, such that detection and control are coplanar, and high precision and simple design are realized.

A power tool including a housing, a controller within the housing, and a brushless motor within the housing and controlled by the controller. The brushless motor including a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth. The stator assembly defines a stator envelope in an axial direction extending between axial ends of stator end caps of the stator assembly. The brushless motor further includes a rotor assembly including a rotor core having rotor laminations and defining a central aperture that extends in the axial direction and that receives a shaft, and a position sensor board assembly including position sensors and configured to provide position information of the rotor core to the controller. The rotor assembly and the position sensor board assembly are provided at least partially within the stator envelope.