According to an aspect, there is provided an apparatus for performing angular position error estimation. The apparatus operates (601) a synchronous motor (111) according to a pre-defined pulsating torque signal using a sensorless vector control method with high-frequency voltage injection. The pre-defined pulsating torque signal has a zero mean and corresponds to a torque operating point. The apparatus measures (602) a first value of an estimated angular position at a first time instance corresponding substantially to an end point of the pre-defined pulsating torque signal and second values of the estimated angular position and an estimated angular speed at a second time instance occurring after the first time instance. Based on the measured values, the apparatus estimates (603) an error in the estimated angular position and stores (604) the error to a lookup table. After performing said steps for one or more pre-defined pulsating torque signals, the apparatus operates (607) the synchronous motor (111) using the lookup table for angular position error correction.

An optical driving mechanism is provided, disposed in an electronic device, including a movable portion, a fixed portion, and a sensing assembly. The movable portion has a holder configured to sustain an optical element. The fixed portion is affixed in the electronic element and connects to the movable portion, wherein the movable portion is movable relative to the fixed portion by applying a magnetic force. The sensing assembly has a coil and a magnetic element configured to sense the relative positions of the movable portion and the fixed portion.

A machine learning device includes: a state observer that observes, as a state variable, at least one of driving noise of a synchronous rotating machine and an error with respect to a preset position of a rotational position of the synchronous rotating machine determined by driving voltage; and a learner that determines a value of a parameter on a basis of the state variable observed by the state observer. The learner includes: a reward calculator that calculates a reward on a basis of the state variable; and a function updater that determines the value of the parameter on a basis of the reward that has been calculated. The reward calculator increases the reward when the driving noise is smaller than a target value of driving noise.

A controller of a power tool outputs a driving signal to a motor driving circuit and acquires a position of a rotor of a brushless motor. While acquiring the position of the rotor of the brushless motor, a phase voltage or a line voltage of a winding of the brushless motor is detected through the voltage detection circuit. Whether an upper bridge arm switching element, a lower bridge arm switching element, and/or the brushless motor is short-circuited is determined according to the phase voltage or the line voltage of the winding of the brushless motor

A system for determining an initial angular position of a rotor of a synchronous machine includes a motor driver module configured to provide a motor driver voltage signal to the synchronous machine, the motor driver voltage signal being sufficient to induce an electrical current in the synchronous machine; and a rotor position determination module configured to receive an indication of the current generated in the machine and to determine the initial position of the rotor based on the indication of the current generated in the machine.

A pole direction detection device for detecting a pole direction of a synchronous motor having saliency comprises a high-frequency voltage application unit that applies a high-frequency voltage to the motor; an excitation phase change unit that changes an excitation phase of the motor to an arbitrary phase; a driving current detection unit that detects a driving current value of the motor; a pole direction estimation unit that detects a pole direction based on the excitation phase and the driving current value; a measurement unit that measures an inductance value of the motor; and a control unit that changes a frequency of the high-frequency voltage to be applied by the high-frequency voltage application unit based on the inductance value measured by the measurement unit.

A method of estimating an operating state of a drive system is presented. The drive system comprises an electric motor and a mechanical unit being moved by the electric motor. The method comprises a) operating the electric motor using electrical properties, b) determining movement properties regarding the movement of the mechanical unit using the electrical properties, repeating steps a) and b) for a number of times using changed electrical properties, and generating a distribution function. The distribution function allocates electrical properties to the resulting movement properties. The method also comprises estimating the operating state in response to the generated distribution function.

An electric motor control device performing feedback control of a state amount of an electric motor or a load and being capable of changing a control bandwidth of a feedback control system includes: a notch filter arranged in the feedback control system and having a filter coefficient which is changeable; a notch control section which changes a notch frequency as a center frequency of the notch filter to remove an oscillation component attributable to mechanical resonance related to the electric motor; and a control coefficient setting section which changes at least one of the control bandwidth or the filter coefficient of the notch filter in accordance with the control bandwidth and the notch frequency to stabilize the feedback control system.

A method and an apparatus may detect a rotor magnetic pole of a single-phase BLDC motor. The method and apparatus may quickly and precisely initially drive the single-phase BLDC motor by detecting a position of a magnetic pole of a rotor adjacent to a stator by applying a high frequency voltage to the single-phase BLDC motor and analyzing a magnitude of a flowing current.

A machine learning device includes: a state observer that observes, as a state variable, at least one of driving noise of a synchronous rotating machine and an error with respect to a preset position of a rotational position of the synchronous rotating machine determined by driving voltage; and a learner that determines a value of a parameter on a basis of the state variable observed by the state observer. The learner includes: a reward calculator that calculates a reward on a basis of the state variable; and a function updater that determines the value of the parameter on a basis of the reward that has been calculated. The reward calculator increases the reward when the driving noise is smaller than a target value of driving noise.