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1. (WO2014199139) SURFACE CLEANING APPLIANCE

Pub. No.:    WO/2014/199139    International Application No.:    PCT/GB2014/051780
Publication Date: Fri Dec 19 00:59:59 CET 2014 International Filing Date: Wed Jun 11 01:59:59 CEST 2014
IPC: A47L 9/28
Applicants: DYSON TECHNOLOGY LIMITED
Inventors: ZHENG, Libo
ZHOU, Yongji
CHISHOLM, James
HAWKER, David
Title: SURFACE CLEANING APPLIANCE
Abstract:
A surface cleaning appliance comprising a cleaner head comprising an agitator and a motor for driving the agitator. The appliance further comprises a switch coupling the motor to a supply voltage, a voltage sensor for measuring the magnitude of the supply voltage, a current sensor for measuring the magnitude of current through the motor,and a controller configured to output a PWM signal for controlling the switch. The controller then adjusts the duty cycle of the PWM signal in response to changes in the supply voltage and in response to changes in the current through the motor.