Method of controlling a brushless permanent-magnet motor

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

A method of controlling a brushless permanent-magnet motor, the method comprising commutating a winding of the motor at times relative to zero-crossings of back EMF in the winding, wherein commutation is advanced when the motor operates over a first speed range, commutation is retarded when the motor operates over a second speed range, commutation is synchronised when the motor operates over a fourth speed range, the second speed range is higher than the first speed range, and the fourth speed range is lower than the first speed range.

A control circuit for a brushless permanent-magnet motor, the control circuit being configured to commutate a winding of the motor at times relative to zero-crossings of back EMF in the winding, wherein commutation is advanced when the motor operates over a first speed range, commutation is retarded when the motor operates over a second speed range, and the second speed range is higher than the first speed range.

A control circuit for a brushless permanent-magnet motor, the control circuit being configured to commutate a winding of the motor at times relative to zero-crossings of back EMF in the winding, wherein commutation is advanced when the motor operates over a first speed range and when the motor operates over a third speed range, commutation is retarded when the motor operates over a second speed range, the second speed range is higher than the first speed range, and the third speed range is higher than the second speed range.

A control circuit for a brushless permanent-magnet motor, the control circuit being configured to commutate a winding of the motor at times relative to zero-crossings of back EMF in the winding, wherein commutation is advanced when the motor operates over a first speed range, commutation is retarded when the motor operates over a second speed range, commutation is synchronised when the motor operates over a fourth speed range, the second speed range is higher than the first speed range, and the fourth speed range is lower than the first speed range.