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 motor driving apparatus for a cleaning appliance includes a battery source and a power controller. The battery source supplies the power controller with an output having a first voltage which decreases as the battery source is discharged. The power controller modulates the output to produce a drive signal for driving a motor that has a second voltage and a variable duty cycle. The power controller increases the duty cycle of the drive signal as the first voltage decreases in order to maintain the second voltage at a substantially constant average value per unit time. By providing the above arrangement, the motor can be supplied with a constant voltage throughout the available run time of the battery. When forming part of a cleaning appliance having a motor, the above arrangement allows the motor to operate at a substantially constant speed throughout the run time of the battery.

Abstract: A cleaning appliance includes a main body, a filter and an interlock. The main body includes an airflow generator, a separating apparatus separating dirt and dust from an airflow, and a flowpath between the separating apparatus and the airflow generator delimited by a wall. The interlock has a first part located on the filter and a second part located on the main body outside the flowpath, arranged to communicate remotely when the filter is correctly located in the pre-determined position. The interlock is arranged selectively to allow or prevent operation of the airflow generator depending upon the relative separation between the first and second parts. By providing an interlock which has first and second parts which communicate remotely, the second part located on the main body can be isolated from the airflow path so that the second part is not subject to dirt and dust carried by the airflow.

Abstract: A motor driving apparatus for a cleaning appliance includes a battery source and a power controller. The battery source supplies the power controller with an output having a first voltage which decreases as the battery source is discharged. The power controller modulates the output to produce a drive signal for driving a motor that has a second voltage and a variable duty cycle. The power controller increases the duty cycle of the drive signal as the first voltage decreases in order to maintain the second voltage at a substantially constant average value per unit time. By providing the above arrangement, the motor can be supplied with a constant voltage throughout the available run time of the battery. When forming part of a cleaning appliance having a motor, the above arrangement allows the motor to operate at a substantially constant speed throughout the run time of the battery.

Abstract: A cleaning appliance includes a main body, a filter and an interlock. The main body includes an airflow generator, a separating apparatus separating dirt and dust from an airflow, and a flowpath between the separating apparatus and the airflow generator delimited by a wall. The interlock has a first part located on the filter and a second part located on the main body outside the flowpath, arranged to communicate remotely when the filter is correctly located in the pre-determined position. The interlock is arranged selectively to allow or prevent operation of the airflow generator depending upon the relative separation between the first and second parts. By providing an interlock which has first and second parts which communicate remotely, the second part located on the main body can be isolated from the airflow path so that the second part is not subject to dirt and dust carried by the airflow.