One or more examples relate, generally, to an orientation of a rotor. Some examples relate to an apparatus. The apparatus may include sample-accumulation logic to generate, over a time duration, a value indicative of inductance at least partially responsive to a probe signal provided to a stator of a motor. The apparatus may also include a probe-current discriminator to generate a further value indicative of an orientation of a rotor of the motor at least partially responsive to the generated value. The apparatus may also include update logic to update a process variable of a control loop at least partially responsive to a state of the further value.

A method for sensorless control of an electric motor implemented in a variable speed drive including: determining a control voltage to be applied to the motor; injecting a high frequency signal to the control voltage to obtain an excitation voltage, wherein one or more frequencies of the high frequency signal varies with time; applying the excitation voltage to the motor; measuring a current signal induced in the motor by the excitation voltage, wherein the current signal comprises a fundamental current, induced by the control voltage, and a disturbance current, induced by the high frequency signal; and demodulating the current signal.

A method determines a rotor position of an electric rotating machine which is fed by a PWM-controlled inverter. Specific injection voltages, which are composed of predefined voltages and high-frequency voltages, are converted into corresponding PWM duty factors by a controller and the inverter is correspondingly actuated with these PWM duty factors. Current profiles of phase currents are then determined by measuring at least one first phase current and at least one second phase current. The measurement is carried out within a PWM period, in each case in the chronologically last third of a passive switched state. The rotor position is then determined in accordance with the ascertained current profiles and the fed-in high-frequency voltages.

In a position control device that controls a rotational speed and a rotational angle of a three-phase synchronous motor by calculating a d-axis current command value and a q-axis current command value based on a position command and causing a inverter to adjust current values of respective phases of the three-phase synchronous motor, a processor calculates a d-axis additional current value to be added to the d-axis current command value. The d-axis additional current value oscillates in such a manner that the polarity changes according to an electrical angle and crosses a zero level with an inclination whose polarity is opposite the polarity of a first q-axis current command value at a zero-cross electrical angle. As a result, positional deviation ripples caused by dead time can be suppressed.

Saliency tracking for brushless direct current (BLDC) motors and other permanent magnet synchronous motors (PMSMs) is provided. Embodiments generate an accurate estimate of rotor position for use in field-oriented control (FOC) of BLDC motors. In addition, a robust saliency tracking algorithm provides for the use of BLDC motors in low-speed high-torque applications without the need of external sensors. This enables sensorless application of higher level algorithms as well, such as servo control. In addition, accurate measurement of motor phase inductance and flux linkage can be provided without any additional equipment.

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.

In the position sensorless control method in low-speed region of the fault-tolerant permanent magnet motor system based on the envelope detection and the non-orthogonal phase-locked loop of the present disclosure, the position sensorless control of the motor is implemented by injecting the high-frequency voltage signals into any two non-faulty phase windings of the motor, extracting the high-frequency response currents of the high-frequency injected phases by the digital bandpass filter, calculating the differential mode inductances of the two phase windings through the envelope detecting and signal processing, and extracting the rotor position and rotational speed signals from the estimated two phase inductances through the non-orthogonal phase-locked loop. In addition, the controller of the present disclosure is small in size, high in accuracy, and high in reliability, which can effectively meet the performance requirements of the onboard electric actuators.

A driving circuit for an electric motor including multiple windings includes a sensing circuit to sense motor winding currents. A motor rotation angle signal is generated from the sensed currents and motor control voltages are generated as a function of the motor rotation angle signal. The motor windings are driven with motor drive voltages obtained by injecting into the motor control voltages injection pulses. The sensed currents include both torque components and injection components. The motor rotation angle signal is generated as a function of the injection components of the sensed currents.

A method for determining a rotor frequency and/or a rotor angle of a rotor of a reluctance machine, in particular without an amortisseur, is disclosed. The reluctance machine has a stator with a stator winding and the rotor has a magnetically anisotropic rotor core. The method includes applying a temporal sequence of voltage pulses to the stator winding, determining a sequential pulse response of a current flowing in the stator winding, the current being generated as a result of the voltage pulses and a flux being generated from the voltage pulses as a result of the magnetically anisotropic rotor core, and determining the rotor frequency and/or the rotor angle based on the measured sequential pulse response of the electric current by using an evaluating device.

A method for operating a brushless direct current motor wherein, by the energization of a plurality of armature coils which are arranged on a stator and form a three-phase current winding for generating a rotating field which rotates around the stator, and having three terminals, a rotating field is generated in order to drive a rotor, which is rotatable about an axis of rotation relative to the stator and has at least two opposing permanent magnet poles. For the determination of the position of the rotor relative to the stator a measurement voltage signal is applied between a first and second of the terminals, a resulting voltage is measured on a third of the terminals, a gradient value which indicates the gradient of the resulting voltage in a time interval is determined with reference to the progression over time of the resulting voltage.