Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
146 words
A method of starting a brushless direct current motor (M), including the successive steps of (a) energising the motor windings (X, Y, Z) to move the rotor to a predetermined position; (b) applying a drive current pulse to the appropriate winding phase to cause the rotor to turn from the predetermined position in a predetermined direction of rotation; (c) sampling the back EMFs generated in the motor windings (X, Y, Z) when the current pulse has decayed to a level where the I×R voltage drops in the motor windings are substantially less than the back EMFs in order to indicate whether a change in commutation is required to keep the rotor turning in the predetermined direction; and (d) applying a drive current pulse to the appropriate winding phase in response to the indication provided by step (c) to keep the rotor turning in the predetermined direction.
Claim 2
Independent Claim
146 words
A method of starting a brushless direct current motor (M), including the successive steps of (a) energising the motor windings (X, Y, Z) to move the rotor to a predetermined position; (b) applying a drive current pulse to the appropriate winding phase to cause the rotor to turn from the predetermined position in a predetermined direction of rotation; (c) sampling the back EMFs generated in the motor windings (X, Y, Z) when the current pulse has decayed to a level where the I×R voltage drops in the motor windings are substantially less than the back EMFs in order to indicate whether a change in commutation is required to keep the rotor turning in the predetermined direction; and (d) applying a drive current pulse to the appropriate winding phase in response to the indication provided by step (c) to keep the rotor turning in the predetermined direction.
Claim 3
Dependent Claim
50 words
A method as claimed in claim 1, further including the steps of: (e) determining the rotor position from the sampled back EMFs; and (f) applying a drive current pulse to the appropriate winding phase to turn the rotor in the predetermined direction from the rotor position determined in step (e).
Claim 4
Dependent Claim
62 words
A method as claimed in claim 2, further comprising repeating steps (e) to (f) until the motor reached a speed at which the back EMFs are significantly greater than the IR losses in the windings and then commutating the motor in dependence on the current position of the rotor as indicated by continuous comparison of the back EMFs generated in the windings.
Claim 5
Dependent Claim
146 words
A drive arrangement including a brushless direct current motor (M); means to energise the motor windings (X, Y, Z) to move the rotor to a predetermined position; means to apply a drive current pulse to the appropriate winding phase to cause the rotor to turn from the predetermined position in a predetermined direction of rotation; sampling means to sample the back EMFs generated in the motor windings (X, Y, Z) when the current pulse has decayed to a level where the I×R voltage drops in the windings are substantially less than the back EMFs in order to indicate whether a change in commutation is required to keep the rotor turning in the predetermined direction; and means to apply a drive current pulse to the appropriate winding phase in response to the indication provided by the sampling means to keep the rotor turning in the predetermined direction.
Claim 6
Dependent Claim
146 words
A drive arrangement including a brushless direct current motor (M); means to energise the motor windings (X, Y, Z) to move the rotor to a predetermined position; means to apply a drive current pulse to the appropriate winding phase to cause the rotor to turn from the predetermined position in a predetermined direction of rotation; sampling means to sample the back EMFs generated in the motor windings (X, Y, Z) when the current pulse has decayed to a level where the I×R voltage drops in the windings are substantially less than the back EMFs in order to indicate whether a change in commutation is required to keep the rotor turning in the predetermined direction; and means to apply a drive current pulse to the appropriate winding phase in response to the indication provided by the sampling means to keep the rotor turning in the predetermined direction.