Provided is a method of controlling a sensorless motor for an air compressor. The method controls early driving of a sensorless motor for an air compressor, overcomes related-art problems, and improves control response. A position of a rotor of the motor, finally estimated by a sensorless control logic at a point in time at which the motor is determined to be in the stopped state, is determined to be an alignment target position. An alignment start position is determined from the alignment target position in accordance with a predetermined alignment offset angle. The position of the rotor of the motor is controlled to change from the determined alignment start position to the alignment target position.

Example systems and processes use three-phase vector mutual inductance analysis to detect zero-crossing (ZC) locations of back-electromotive force (BEMF) of an electric motor and to detect its commutation points during start-up or low-speed operation. For each sector of rotation of the rotor, two pairs of three-phase vectors are applied, along with current for the corresponding driving phase. The first pair is alternately applied to move the rotor, and the mutual inductances resulting from such application are compared to detect the zero-crossing (ZC) location in the BEMF of the electric motor in that sector. The second pair is then alternately applied within the same sector to continue to move the rotor, and the mutual inductances from such application are compared to detect the commutation point of the electric motor in that sector. The process may be repeated for each successive sector, changing the driving current at each new sector.

Example systems and processes use three-phase vector mutual inductance analysis to detect zero-crossing (ZC) locations of back-electromotive force (BEMF) of an electric motor and to detect its commutation points during start-up or low-speed operation. For each sector of rotation of the rotor, two pairs of three-phase vectors are applied, along with current for the corresponding driving phase. The first pair is alternately applied to move the rotor, and the mutual inductances resulting from such application are compared to detect the zero-crossing (ZC) location in the BEMF of the electric motor in that sector. The second pair is then alternately applied within the same sector to continue to move the rotor, and the mutual inductances from such application are compared to detect the commutation point of the electric motor in that sector. The process may be repeated for each successive sector, changing the driving current at each new sector.

A closed-loop method of starting a permanent magnet synchronous motor comprises driving the rotor by energizing stator windings using motor control signals based on an initial standstill rotor angle. Periodically estimating values of rotor flux linkage magnitude and/or angle based on back-electromotive force (emf) induced in the stator windings by the rotating rotor. The estimated values of rotor flux linkage magnitude are used to estimate respective new rotor angles which are used to generate updated motor control signals to drive the rotor. Control of the motor is switched-over to a closed-loop synchronous operation motor control algorithm in response to any one or any combination of the following conditions: at a predetermined period of time from initiation of the closed-loop start-up method; or upon determination that the rotor has reached a minimum operating speed; or upon determination that the estimated value of rotor flux linkage magnitude reaches or exceeds a threshold value.

The present disclosure provides a driving circuit of a fan motor to shorten a start time. The driving circuit drives the fan motor with a sensor. A control logic circuit controls an inverter circuit connected to the fan motor according to a Hall signal that indicates a position of a rotor of the fan motor. When the driving circuit is given an instruction to start a rotation, if the fan motor rotates at a speed lower than a predetermined rotational speed, the drive circuit starts the fan motor by sequentially switching between a second state in which the rotor is fixed at an initial position, a third state in which the fan motor is forcibly and synchronously started, and a fourth state in which the fan motor is Hall-driven.

A method of starting an integrated starter generator drives a starter generator without using a rotor position sensor to start an engine. The method includes the following steps of: (a) applying a first drive current with a first frequency and a first amplitude to drive the starter generator to reversely rotate in a speed open-loop control mode, and acquiring a first load information according to a drive voltage and the first drive current of the starter generator, (b) confirming whether the first load information meets a heavy load condition, (c) stopping reversely rotating the starter generator when the first load information meets the heavy load condition, and (d) forwardly rotating the starter generator to drive the engine to start.

A motor control actuator that drives a permanent magnet synchronous motor (PMSM) with sensorless Field Oriented Control includes a sampling circuit that generates a measurement signal by measuring a back electro motive force (BEMF) of the PMSM, while the PMSM rotates; a PLL that receives the measurement signal and extracts an amplitude and an angle of the BEMF from the measurement signal; and a motor controller that generates a first set of two phase alternating current (AC) voltage components based on an estimated rotor angle, generates a second set of two phase AC voltage components based on the amplitude and the angle, and generates control signals for driving the PMSM based on the first set of two phase AC voltage components. The motor controller performs a catch spin sequence for restarting the PMSM while rotating, the catch spin sequence includes a synchronizing period followed by a closed loop control period.

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 apply a drive signal to the power switch circuit to control the supply of power to the brushless motor. The controller is 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 within a variable speed range of zero to at least 15,000 rotations-per-minute (RPM), and control the drive signal based on the detected angular position of the rotor to electronically commutate the motor within a torque range of zero to at least 15 newton-meters (N.m.) and a power output of zero to at least 1500 watts.

A motor driving method includes steps of: at an open loop phase and in response to a motor being operated under a steady-state, calculating an angle difference between an estimation coordinate axis of the motor and an actual coordinate axis by a controller, according to an estimation voltage value, an estimation current value and at least one electrical parameter feedback from the motor and in reference with the estimation coordinate axis of the motor; calculating an actual current value in reference with the actual coordinate axis according to the angle difference by the controller; calculating a load torque estimation value associated with the motor according to the actual current value by the controller; and, in response to the open loop phase being switched to a close loop phase, compensating an output torque of the motor according to the load torque estimation value by the controller.

A method for starting a sensorless single-phase electric motor. The electric motor includes a permanent magnetic motor rotor, an electromagnetic motor stator having a stator coil, a power electronics which energizes the stator coil, a current sensor which measures a current flowing in the stator coil, and a control electronics which controls the power electronics. The control electronics is connected with the current sensor. The method includes energizing the stator coil with an alternating drive voltage, monitoring a drive current which is generated in the stator coil by the alternating drive voltage, and commutating the alternating drive voltage whenever the drive current reaches a predefined positive current threshold value or a predefined negative current threshold value.