Driving an electromotor and a brushed electromotor in particular results in ripples in the supply current. The amount of pulses is proportional to the amount of revolutions of the rotor of the electromotor. With a flawless motor, the amount of pulses is the same with each revolution. Flaws of the electromotor, in brushes, rotor, windings and/or other components, results in fluctuations of pulses in the supply current per revolution of the rotor. By comparing an expected amount of pulses to counted pulses and using various physical parameters of the electromotor, various methods may be employed to correct a counted amount of pulses or otherwise provide an appropriate value representing displacement of the rotor of the electromotor. The time between counted pulses may also be used for determining slip of a slip coupling comprised by a drive train to which the electromotor may be coupled.

A control unit is presented for controlling a driving unit arranged for adjustment of one or more first air guiding flaps of a motorised vehicle between a first outer position and a second outer position. The control unit comprises a communication module for communicating with a vehicle control network for receiving first adjustment instructions for adjusting the first flap, a power supply module comprising an input power terminal for receiving power from a vehicle power network and a first output power terminal for supplying a first current to the driving unit. The control unit further comprises a current sensor module for sensing variations in the first supply current and a control module arranged to control the first supply current in accordance with the adjustment instructions and the sensed variations. By separating the control module from the driving unit, functionality of the control module may be shared over multiple driving units.

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 configured to compute a position of the rotor based on a characteristic of the current ripple.

A motor control system includes a variable voltage supply in signal communication with a direct current (DC) motor. The DC motor includes a rotor induced to rotate in response to a drive current generated by a variable supply voltage delivered by the voltage supply. The rotation of the rotor 103 generates a mechanical force that drives a component. A ripple count circuit 104 is configured to filter the drive current based on a rotational speed (ω) of the rotor 103 to generate a filtered drive current signal, and to generate a varying threshold based on the filtered drive current signal. Based on a comparison between the filtered drive current signal and the varying threshold, the ripple count circuit 104 generates a pulsed output signal indicative of the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor.

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.

A motor control device is a device for controlling a drive of a DC motor which is interlocked with an output shaft portion of an actuator. The motor control device includes: a relative position obtainer detecting current fluctuations when switching a connection between a commutator and a brush in the DC motor or when rotating the DC motor and obtaining relative position information of the output shaft portion; and an absolute position obtainer obtaining absolute position information of the output shaft portion using a potentiometer. The motor control device further includes: an actual position setter setting actual position information of the output shaft portion based on at least one of the absolute position information and the relative position information.

A motor control system includes a DC motor and a ripple count circuit. The DC motor includes a rotor that rotates in response to a drive current. The rotation of the rotor generates a mechanical force that drives a component. The ripple count circuit includes an active filter circuit and a parasitic pulse cancellation circuit. The active filter circuit is configured to filter the drive current and to generate a pulsed signal. The parasitic pulse cancelation circuit is in signal communication with the ripple count circuit to receive the pulsed signal and generates a ripple count signal that excludes parasitic pulses included in the pulsed signal having a parasitic voltage level that exceeds a voltage level of a voltage threshold. The parasitic pulse cancelation circuit actively adjusts the voltage level of the voltage threshold based at least in part on a rotational direction of the rotor.

An adjusting device having a DC motor and an adjusting member driven by an output shaft of the DC motor is disclosed. The adjusting device has a power driver coupled to the DC motor for controlling a motor current of the DC motor, a current measurement circuit that is adapted to detect a current consumption of the DC motor and to output a current measurement signal dependent on the number of revolutions of the DC motor, and a computing unit, to which the current measurement signal is input adapted to determine the number of revolutions of the DC motor based on the current measurement signal.

A motor control system includes a direct current (DC) motor and a ripple count circuit. The DC motor includes a rotor induced to rotate in response to a drive current generated by a supply voltage. The rotation of the rotor generates a mechanical force that drives a component. The ripple count circuit includes an active filter circuit and a parasitic pulse cancellation circuit. The active filter circuit is configured to filter the drive current and to generate a pulsed signal containing at least one parasitic pulse. The parasitic pulse cancelation circuit is in signal communication with the ripple count circuit to receive the pulsed signal and to output a ripple count signal based on the pulsed signal. The ripple count signal excludes the at least one parasitic pulse.

A motor control system includes a variable voltage supply in signal communication with a direct current (DC) motor. The DC motor includes a rotor induced to rotate in response to a drive current generated by a variable supply voltage delivered by the voltage supply. The rotation of the rotor (103) generates a mechanical force that drives a component. A ripple count circuit (104) is configured to filter the drive current based on a rotational speed (ω) of the rotor (103) to generate a filtered drive current signal, and to generate a varying threshold based on the filtered drive current signal. Based on a comparison between the filtered drive current signal and the varying threshold, the ripple count circuit (104) generates a pulsed output signal indicative of the rotational speed (ω) of the rotor and a rotational position (θ) of the rotor.