Abstract: A vacuum cleaner with a battery unit for powering the vacuum cleaner is provided. The battery unit includes a plurality of serially connected battery cells and battery management electronics operatively coupled to the battery cells. Two enclosures are provided on either side of a central axis of the vacuum cleaner, each enclosure including a portion of the plurality of battery cells, and a portion of the battery management electronics operatively coupled to the respective portion of the plurality of the battery cells. A link strap interconnects the portions of the battery management electronics.

Abstract: An oral treatment device includes image sensor equipment configured to generate image data indicative of a sequence of images representing at least a portion of an oral cavity of a user. The oral treatment device includes a controller configured to process the image data to determine a movement parameter indicative of movement of the oral treatment device relative to an interproximal gap between adjacent teeth in the oral cavity of the user. The controller is configured to control the oral treatment device to perform an action based on the determined movement parameter.

Abstract: A method of controlling a brushless permanent-magnet motor having a phase winding and a rotor includes monitoring a value indicative of back EMF induced in the phase winding during oscillation of the rotor about a parking position, and using amplitude peaks of the value indicative of back EMF to calculate a time window in which to apply a drive voltage to the phase winding. The method includes setting a timer corresponding to the time window at a subsequent determined amplitude peak and applying a drive voltage to the phase winding during the time window.

Abstract: A method of determining the parked position of a rotor of a permanent-magnet motor, including applying a first voltage to a phase winding of the motor, measuring a first parameter, removing the first voltage, waiting for current in the phase winding to decrease to zero, applying a second voltage having the opposite polarity, measuring a second parameter, comparing the first parameter and the second parameter, and determining that the rotor is in a first parked position if the first parameter is less than the second parameter, and that the rotor is in a second parked position if the first parameter is greater than the second parameter. The first parameter and the second parameter each correspond to one of (i) the time taken for current in the phase winding to exceed a threshold, and (ii) the magnitude of current in the phase winding at the end of a time interval.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes generating a first signal having a voltage that is proportional to a voltage across a winding of the motor, and generating a second signal having a voltage that is proportional to a current in the winding. The second signal is then differentiated to generate a third signal, and the voltages of the first signal and the third signal are compared. An output signal is generated in response to the comparison, the output signal having an edge whenever the voltages of the first signal and the third signal correspond. The winding is then commutated at times relative to the edges in the output signal. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A method of determining the position of a rotor of a permanent-magnet motor. The method includes sequentially exciting and freewheeling a winding of the motor. The winding is freewheeled for a freewheel period in response to current in the winding exceeding a current limit. The method also includes measuring a parameter that corresponds to either the magnitude of current in the winding at the end of the freewheel period or the interval between the start or end of the freewheel period and the time at which current in the winding exceeds the current limit. The measured parameter is then compared against a threshold and the rotor is determined to be at a predetermined position when the measured parameter is less than or greater than the threshold.

Abstract: A method of determining the position of a rotor of a permanent-magnet motor. The method uses two different schemes to determine the position of the rotor. A first scheme is used when the rotor rotates within a first speed range, by sequentially exciting and freewheeling a winding of the motor, measuring a parameter that depends on the rate of change of current in the winding, and comparing the parameter against a threshold. A second scheme is used when the rotor rotates within a second speed range, by generating a voltage signal that is proportional to the voltage across the winding, generating a further voltage signal that depends on the rate of change of current in the winding, and comparing the two signals.

Abstract: A method of determining the position of a rotor of a permanent-magnet motor. The method uses two different schemes to determine the position of the rotor. A first scheme is used when the rotor rotates within a first speed range, by sequentially exciting and freewheeling a winding of the motor, measuring a parameter that depends on the rate of change of current in the winding, and comparing the parameter against a threshold. A second scheme is used when the rotor rotates within a second speed range, by generating a voltage signal that is proportional to the voltage across the winding, generating a further voltage signal that depends on the rate of change of current in the winding, and comparing the two signals.

Abstract: A method of determining the position of a rotor of a permanent-magnet motor. The method includes sequentially exciting and freewheeling a winding of the motor. The winding is freewheeled for a freewheel period in response to current in the winding exceeding a current limit. The method also includes measuring a parameter that corresponds to either the magnitude of current in the winding at the end of the freewheel period or the interval between the start or end of the freewheel period and the time at which current in the winding exceeds the current limit. The measured parameter is then compared against a threshold and the rotor is determined to be at a predetermined position when the measured parameter is less than or greater than the threshold.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes generating a first signal having a voltage that is proportional to a voltage across a winding of the motor, and generating a second signal having a voltage that is proportional to a current in the winding. The second signal is then differentiated to generate a third signal, and the voltages of the first signal and the third signal are compared. An output signal is generated in response to the comparison, the output signal having an edge whenever the voltages of the first signal and the third signal correspond. The winding is then commutated at times relative to the edges in the output signal. Additionally, a control system that implements the method, and a motor system that incorporates the control system.