A permanent magnet synchronous machine (1) having a rotor (R) and a stator (S). Connection terminals (2) apply a feed alternating voltage with a feed frequency (f.sub.0). The permanent magnet synchronous machine (1) has a motor controller (10). The controller (10) has an assembly (11) to detect the terminal voltage on the connection terminals (2) and the current frequency (f.sub.a). Also, the controller has an analysis device (12). The analysis device (12) ascertains whether the current frequency (f.sub.a) contains a frequency component (f.sub.r) with a frequency that deviates from the feed frequency (f.sub.0).

An electric machine includes a rotor, a stator, at least one measurement circuit, and a controller. The rotor includes a plurality of salient poles arranged radially around a rotation axis of the electric machine and spaced apart from the rotation axis of the electric machine. The stator includes a plurality of coils configured to selectively align with the plurality of salient poles of the rotor. The at least one measurement circuit is configured to measure at least one current through at least one of the plurality of coils. The measured current includes a current ripple. The controller is configured to compute a position of the rotor based on a characteristic of the current ripple.

A method for determining a movement of a rotor of an electric motor, comprises supplying a drive signal to a drive coil of the electric motor, sensing a coil current of the drive coil, detecting current ripples of the sensed coil current caused by the rotor of the electric motor crossing ripple generating positions, inferring the movement of the rotor from the detected ripples, braking the motor by reducing the drive signal supplied to the drive coil from an initial signal value to zero according to a braking curve specifying a non-zero fall time during which the drive signal is reduced from the initial signal value to zero. The braking curve is adapted so that the rotor does not cross a ripple generating position after the drive signal has been reduced to zero.

A six phase stator winding of a motor that has reduced MMF harmonics characteristics is provided. The stator winding has two sets: a first set and a second set of three phase winding connection. The first set and the second set of the three phase winding connection are connected parallel to each other, such that the two sets of the three-phases are shifted by 30-degree electrical angle with respect to each other, where the second set of is leading.

A method for determining a rotation variable of a rotatably mounted rotor of a mechanically commutated electric motor, having a motor current path formed between two brush elements of the electric motor, and leading via the commutator bars contacted by the brush elements, and via coil windings of the rotor electrically connected to said commutator bars, wherein an oscillating input signal is fed into the motor current path and the rotation variable is determined with the aid of a ripple of a resultant output signal, said ripple being due to the mechanical commutation of the motor current path.

The invention provides a noise filtering method for a motor. The motor rotates according to an operating voltage. The noise filtering method includes: setting an inspection period and a minimum threshold. The noise filtering method further includes: generating a pulse signal according to the operating voltage, determining whether a time corresponding to each sub-pulse signal in the pulse signal meets the inspection period, and determining whether a pulse width corresponding to each sub-pulse signal is equal to or greater than the minimum threshold. A recording medium storing a program code corresponding to the method, and a motor control circuit for executing the program code are also provided.

A drive unit for an adjustment system for a motor vehicle has an adjustable element moved by an electric motor. The dive motor is operated electromagnetically. A magnetic field sensor is arranged on a pole pot or a housing of the drive motor to provide an electrical sensor signal dependent on a magnetic field. A control unit is configured to detect the magnetic field. The magnetic field varies on rotation of a rotor of the drive motor, so that a relative position change of the adjustable element can be derived from the electrical sensor signal.

A rotation angle detector includes a rotational angular velocity calculator that calculates a rotational angular velocity of a motor based on an inter-terminal voltage of the motor detected by a voltage detector and a current flowing through the motor and detected by a current detector; a ripple detector that detects a ripple component included in the current; and a failure detector that detects a failure of any one of the voltage detector, the current detector, and the ripple detector based on outputs from the detectors. The failure detector determines that the failure has occurred when a state, where the outputs from two of the voltage detector, the current detector, and the ripple detector indicate normal rotation and the output from the remaining one of the voltage detector, the current detector, and the ripple detector does not indicate normal rotation, continues for a predetermined period of time.

A slotless synchronous permanent magnet motor includes a rotor, and a stator configured to electromagnetically interact with the rotor. The rotor is provided with a first conductive metal layer configured to create harmonic rotor saliency.

An apparatus for estimating a motor RPM in an electronic brake system may include: a current signal amplifier configured to amplify a voltage applied across a motor driver by a current which flows while the motor driver is turned on, the motor driver being included in a motor driving circuit configured to apply motor driving power to a motor or remove the motor driving power according to a switch-on/off of the motor driver; and a controller configured to detect a waveform with a one-period time from periodically repeated waveforms by processing the signal waveform amplified by the current signal amplifier, calculate a one-rotation time based on the one-period time and the number of commutators of the motor, and calculate a motor RPM using the one-rotation time.