Dyson Technology Limited

Yongji Zhou

Libo Zheng

Tuncay Celik

Hanping Dai

Yu Chen

David John Hawker

James Douglas Chisholm

Dai Hanping

James Chisholm

A surface cleaning appliance having a cleaner head that includes an agitator and a motor for driving the agitator. The appliance includes 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.

Surface cleaning appliance

A method of controlling a brushless permanent-magnet motor. The method includes commutating a winding of the motor at times relative to zero-crossings of back EMF in the winding. Commutation is then advanced when the motor operates over a first speed range, and commutation is retarded when the motor operates over a second speed range higher than that of the first speed range.

Method of controlling a brushless permanent-magnet motor

A controller for a brushless motor that includes a PWM module configured in half-bridge or full-bridge mode. The PWM module outputs control signals for controlling the excitation of a winding of the motor, and one of the duty cycle and the period of the PWM module defines a time at which the winding is commutated.

Controller for a brushless motor

A controller for a brushless motor that is configured to operate in normal mode or under-voltage mode. When operating in normal mode, the controller generates control signals for exciting a winding of the motor, monitors the magnitude of an input voltage, and switches to under-voltage mode in the event that the input voltage drops below an under-voltage threshold. When operating in under-voltage mode, the controller suspends excitation of the winding, monitors the magnitude of the input voltage, monitors the magnitude of a supply voltage used to power the controller, switches to normal mode in the event that the input voltage exceeds a restart threshold, and resets itself in the event that the supply voltage drops below a brown-out threshold.

A method of controlling an electrical machine that includes selecting an edge of a rotor-position signal as a reference edge and commutating a phase winding of the electrical machine at times relative to the reference edge. The rotor-position signal has at least four edges per mechanical cycle, each of the edges being associated with a respective zero-crossing in back EMF or minimum in inductance of the phase winding. The angular position of at least one of the edges relative to its respective zero-crossing or minimum is different to that of the other edges. The reference edge is then selected from the edges such that the angular position of the reference edge relative to its respective zero-crossing or minimum is the same with each power on of the electrical machine. Additionally, a controller and control system that implement the method.

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Swindon, United Kingdom

Yongji Zhou