Control of a brushless permanent-magnet motor
AssigneeDyson Technology Limited
InventorsAndrew Charlton CLOTHIER, Stephen Greetham
Life of this patent
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Abstract
A method of controlling a brushless permanent-magnet motor that includes rectifying an alternating voltage to provide a rectified voltage having a ripple of at least 50%, and exciting a winding of the motor with the rectified voltage. The winding is excited in advance of zero-crossings of back EMF by an advance period and is excited for a conduction period over each electrical half-cycle of the motor. The advance period and/or the conduction period are then adjusted in response to changes in the speed of the motor and/or the RMS value of the alternating voltage so as to maintain constant average power. Additionally, a control system that implements the method, and a motor system that incorporates the control system.
Claims19
A method of controlling a brushless permanent-magnet motor, the method comprising:
- rectifying an alternating voltage to provide a rectified voltage having a ripple of at least 50%;
- exciting a winding of the motor with the rectified voltage, the winding being excited in advance of zero-crossings of back EMF by an advance period and being excited for a conduction period over each electrical half-cycle of the motor;
- and
- adjusting one of the advance period and the conduction period in response to changes in one of motor speed and RMS value of the alternating voltage so as to maintain constant average power.
Dependencies are inferred from the claim text.