A method for determining an initial rotor position of a permanent magnet synchronous motor (PMSM) includes: generating a plurality of transient currents by applying a plurality of voltages to each phase stator winding of a three phase stator winding of the PMSM; generating three phase current differences according to the plurality of transient currents; determining a first zone in which the initial rotor position of the PMSM is located according to the three phase current differences, wherein angles between 0-360 degrees are divided into a plurality of zones, and the first zone is selected from the plurality of zones; calculating three line current differences according to the three phase current differences; and determining the initial rotor position of the PMSM according to the first zone and the three line current differences.

A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.

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.

An external force estimation device is configured to estimate an external force acting on a motor. The external force estimation device includes a processor. The processor is configured to: calculate an output torque of the motor by using a value of a current supplied to the motor; estimate an inertia torque of the motor by using rotational position information of the motor; estimate a first friction torque of the motor by using the rotational position information of the motor; perform temperature-based correction for the first friction torque by using temperature information of the motor; and estimate the external force by subtracting the inertia torque and the first friction torque after the temperature-based correction from the output torque.

A control circuit arranged to detect an initial rotor position of a brushless DC motor includes: a voltage integrator circuit, arranged to perform integration upon an input voltage, to generate a plurality of integrated voltages; a PWM generating circuit, arranged to generate and output a plurality of PWM signals to the brushless DC motor through a drive circuit, and stop outputting a PWM signal that is any of the plurality of PWM signals to the brushless DC motor according to an integrated voltage corresponding to the PWM signal; a current receiving circuit, arranged to receive a plurality of feedback currents from the brushless DC motor; a comparison circuit, arranged to perform comparison upon the plurality of feedback currents, to generate a comparison result; and a decision circuit, arranged to detect the initial rotor position according to the comparison result.

A method and a control apparatus for determining parameters for controlling an electric drive having an electric machine improve the start-up of the electric drive by applying a current indicator as a signal at three-phase winding connections of the electric machine, and measuring a d-component and a q-component of the stator voltage and of the stator current at the winding connections. In a first measurement step, a rotating current indicator is applied to the three-phase winding connections and the electric machine is oriented such that an exciter current in the q-axis assumes a minimum. In a second measurement step, when the rotor of the electric machine is stationary, a field winding of the electrical machine is short-circuited and a current indicator in form of a binary noise signal is applied to the winding connections. A stator impedance is then determined as a first control parameter.

A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.

Described is a method of determining an initial rotor position on start-up of a synchronous motor. The method comprises applying at each of a plurality of pre-set motor angles a pair of voltage vector pulses, the pair of voltage vector pulses comprising a first and second pulses, each having the same amplitude but opposite polarities, the second pulse being applied immediately or near immediately after the first pulse. The method includes determining the stator current responses to said pairs of applied voltage vector pulses at said plurality of pre-set motor angles. Then, the initial rotor position can be determined from either of a stator angle corresponding to a pair of vector voltage pulses resulting in (a) a largest sum of stator currents or (b) where the sum of stator currents changes from a negative to a positive motor angle.

Disclosed is a clothes treating apparatus and a control method thereof. Specifically, the clothes treating apparatus may include an inverter configured to convert a direct current (DC) input into an alternating current (AC) output and provide the AC output to the motor, and a controller configured to control the inverter in relation to driving of the motor.

An information related to the position of an actuator coupled to a cable which is coupled to a motor is received. A filter is used to provide an input to a motor controller coupled to the motor, to adjust torque on the motor such that a strength curve is implemented relative to the position of the actuator.