Detection of starting motor position in a brushless DC motor

Claim 2

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, a method for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said method comprising the steps of: coupling circuit means to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; determining a magnitude of at least one of each of said rise time for each said rise time difference; determining ambiguity in sign for each said rise time difference; retesting with said predetermined phase winding tied so as to change effective rotor position; and identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position.

Claim 3

The method of claim 1 wherein the predetermined phase winding is tied high.

Claim 4

The method of claim 2 further comprising the step of: using the initial position of said rotor as identified for determining both polarity and duration of at least one drive pulse for starting the motor, the duration of the drive pulse moving the rotor up to but not passed an initial commutation location.

Claim 5

The method of claim 3 further comprising the step of: controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed.

Claim 6

The method of claim 4 further comprising the step of: regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a desired operating speed.

Claim 7

The method of claim 1 wherein the predetermined phase winding is tied low.

Claim 8

The method of claim 6 further comprising the step of: using the initial position of said rotor as identified for determining both polarity and duration of at least one drive pulse for starting the motor, the duration of the drive pulse moving the rotor up to but not passed an initial commutation location.

Claim 9

The method of claim 7 further comprising the step of: controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position.

Claim 10

The method of claim 8 further comprising the step of: regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 11

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, a method for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said method comprising the steps of: coupling circuit means to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; determining a magnitude of at least one of each of said rise time for each said rise time difference; determining ambiguity in sign for each said rise time difference; retesting with said predetermined phase winding tied high so as to change effective rotor position; and identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 12

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, a method for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said method comprising the steps of: coupling circuit means to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; determining a magnitude of at least one of each of said rise time for each said rise time difference; determining ambiguity in sign for each said rise time difference; retesting with said predetermined phase winding tied high so as to change effective rotor position; and identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 13

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, a method for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said method comprising the steps of: coupling circuit means to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; determining a magnitude of at least one of each of said rise time for each said rise time difference; determining ambiguity in sign for each said rise time difference; retesting with said predetermined phase winding tied low so as to change effective rotor position; identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 14

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, a method for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said method comprising the steps of: coupling circuit means to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; determining a magnitude of at least one of each of said rise time for each said rise time difference; determining ambiguity in sign for each said rise time difference; retesting with said predetermined phase winding tied low so as to change effective rotor position; identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 15

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with positive current to provide positively induced voltage without appreciably altering the electrical position of the rotor and to provide a positively pulsed phase; measuring a first rise time for the positively induced voltage for the positively pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with negative current to provide negatively induced voltage without appreciably altering the electrical position of the rotor and to provide a negatively pulsed phase; measuring a second rise time for the negatively induced voltage for the negatively pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining whether the difference does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the difference does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference; and repeating the steps of the step of mapping until each of the n phases is processed; and recalling and using the sign of the difference for each of the n phases as compared with predetermined stored motor electrical position information to energize at least one of the n phases to start the motor in the predetermined direction.

Claim 16

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with positive current to provide positively induced voltage without appreciably altering the electrical position of the rotor and to provide a positively pulsed phase; measuring a first rise time for the positively induced voltage for the positively pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with negative current to provide negatively induced voltage without appreciably altering the electrical position of the rotor and to provide a negatively pulsed phase; measuring a second rise time for the negatively induced voltage for the negatively pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining whether the difference does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the difference does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference; and repeating the steps of the step of mapping until each of the n phases is processed; and recalling and using the sign of the difference for each of the n phases as compared with predetermined stored motor electrical position information to energize at least one of the n phases to start the motor in the predetermined direction.

Claim 17

The method of claim 12 wherein the step of tying is selected from the group consisting of the steps of: tying high, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; and tying low, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested.

Claim 18

The method of claim 13 further comprising the step of: accelerating the motor to revolve at a medium speed.

Claim 19

The method of claim 14 further comprising the steps of: accelerating the rotor from the medium speed to revolve at a nominal speed; and maintaining the rotor revolving at the nominal speed.

Claim 20

The method of claim 15 wherein n is equal to three.

Claim 21

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for selectively establishing current paths through at least one selected winding in response to control signals; means for successively applying short duration current pulses of opposite polarities to each said selected winding, leaving a predetermined phase open during pulsing; and processing means, having storage means for storing information included therein, for determining and storing each magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level, for subtracting at least one said rise times from another opposite said rise times to provide at least one rise time difference, for determining each sign or absence thereof of each said rise time difference, for determining ambiguity based on each said sign or absence thereof of each said rise time difference, for retesting with said predetermined phase tied high so as to change effective rotor position, and for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position as applicable.

Claim 22

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for selectively establishing current paths through at least one selected winding in response to control signals; means for successively applying short duration current pulses of opposite polarities to each said selected winding, leaving a predetermined phase open during pulsing; and processing means, having storage means for storing information included therein, for determining and storing each magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level, for subtracting at least one said rise times from another opposite said rise times to provide at least one rise time difference, for determining each sign or absence thereof of each said rise time difference, for determining ambiguity based on each said sign or absence thereof of each said rise time difference, for retesting with said predetermined phase tied high so as to change effective rotor position, and for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position as applicable.

Claim 23

The apparatus of claim 17 further comprising: means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position.

Claim 24

The apparatus of claim 18 further comprising: means for regulating a total of said current to said phase windings to accelerate the rotor from the medium speed to a nominal speed, and for maintaining said rotor revolving at said nominal speed.

Claim 25

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for selectively establishing current paths through at least one selected winding in response to control signals; means for successively applying short duration current pulses of opposite polarities to each said selected winding, leaving a predetermined phase open during pulsing; and processing means, having storage means for storing information included therein, for determining and storing each magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level, for subtracting at least one said rise times from another opposite said rise times to provide at least one rise time difference, for determining each sign or absence thereof of each said rise time difference, for determining ambiguity based on each said sign or absence thereof of each said rise time difference, for retesting with said predetermined phase tied low so as to change effective rotor position, and for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position as applicable.

Claim 26

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for selectively establishing current paths through at least one selected winding in response to control signals; means for successively applying short duration current pulses of opposite polarities to each said selected winding, leaving a predetermined phase open during pulsing; and processing means, having storage means for storing information included therein, for determining and storing each magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level, for subtracting at least one said rise times from another opposite said rise times to provide at least one rise time difference, for determining each sign or absence thereof of each said rise time difference, for determining ambiguity based on each said sign or absence thereof of each said rise time difference, for retesting with said predetermined phase tied low so as to change effective rotor position, and for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position as applicable.

Claim 27

The apparatus of claim 20 further comprising: means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position.

Claim 28

The apparatus of claim 21 further comprising: means for regulating a total of said current to said phase windings to accelerate the rotor from the medium speed to a nominal speed, and for maintaining said rotor at said nominal speed.

Claim 29

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position.

Claim 30

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position.

Claim 31

The apparatus of claim 23 wherein the predetermined phase winding is tied high.

Claim 32

The apparatus of claim 24 further comprising: means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position.

Claim 33

The apparatus of claim 25 further comprising: means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 34

The apparatus of claim 23 wherein the predetermined phase winding is tied low.

Claim 35

The apparatus of claim 27 further comprising: means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position.

Claim 36

The apparatus of claim 28 further comprising: means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 37

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied high so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 38

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied high so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 39

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied low so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 40

In a brushless DC motor having multiple phase windings arranged as a stator and a rotor having a permanent magnet and a stator current excitation winding, an apparatus for controlling ordered application of electrical current to the phase windings and measuring responses thereto to determine an initial position of said rotor, said apparatus comprising: circuit means coupled to the phase windings for providing control signals for selectively establishing current paths through at least one selected winding; means for applying short duration current pulses of first and second opposite polarities to each said selected winding for providing at least one energized winding, leaving a predetermined phase winding open during pulsing; means for detecting a voltage corresponding to each of said applied current pulses of opposite polarities as converted by a current to voltage converter connected to the energized winding; means for determining a magnitude for each rise time of each of said responses to said current pulses from zero amplitude to a fixed reference level; means for subtracting at least one of said rise times from one associated one of said rise times to provide at least one rise time difference; means for determining a magnitude of at least one of each of said rise time for each said rise time difference; means for determining ambiguity in sign for each said rise time difference; means for retesting with said predetermined phase winding tied low so as to change effective rotor position; and means for identifying the initial position of said rotor relative to said phase windings based on the sign of the rise time difference between the rise time of the responses to said pulses applied to the selected winding and based on the changed effective rotor position; means for controlling ordered periodic application of the electrical current to said phase windings and measuring the responses thereto to accelerate the rotor to a medium speed from the initial position; and means for regulating a total of said current pulses to said phase windings to accelerate the rotor from the medium speed to a nominal speed and to maintain said rotor revolving at said nominal speed.

Claim 41

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; and mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with positive current to provide positively induced voltage without appreciably altering the electrical position of the rotor and to provide a positively pulsed phase; measuring a first rise time for the positively induced voltage for the positively pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with negative current to provide negatively induced voltage without appreciably altering the electrical position of the rotor and to provide a negatively pulsed phase; measuring a second rise time for the negatively induced voltage for the negatively pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining whether the difference does not provide sufficient information to ultimately resolve the-electrical position of the rotor; tying, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the difference does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference to build up a lookup table, the table for providing a reference for which of the n phases need to be energized to begin rotating the rotor in the predetermined direction; and repeating the steps of the step of mapping until each of the n phases is completely processed.

Claim 42

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; and mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with positive current to provide positively induced voltage without appreciably altering the electrical position of the rotor and to provide a positively pulsed phase; measuring a first rise time for the positively induced voltage for the positively pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with negative current to provide negatively induced voltage without appreciably altering the electrical position of the rotor and to provide a negatively pulsed phase; measuring a second rise time for the negatively induced voltage for the negatively pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining whether the difference does not provide sufficient information to ultimately resolve the-electrical position of the rotor; tying, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the difference does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference to build up a lookup table, the table for providing a reference for which of the n phases need to be energized to begin rotating the rotor in the predetermined direction; and repeating the steps of the step of mapping until each of the n phases is completely processed.

Claim 43

The method of claim 32 wherein the step of tying is selected from the group consisting of the steps of: tying high, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; and tying low, if the difference does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested.

Claim 44

The method of claim 33 wherein n is equal to three.

Claim 45

The method of claim 33 wherein the motor is a spindle motor for a hard disk drive.

Claim 46

The method of claim 33 wherein the n phases are pulsed in a sequential order.

Claim 47

The method of claim 33 wherein the n phases are pulsed in an arbitrary order.

Claim 48

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for determining an initial position of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing each phase of the n phases with a first polarity current to provide first polarity induced voltages without appreciably altering the electrical position of the rotor and to provide first polarity pulsed phases; measuring a first set of rise times for each of the first polarity induced voltages for a one-to-one correspondence with each of the first polarity pulsed phases to reach the threshold induced voltage level; pulsing each said phase of the n phases with a second polarity current to provide second polarity induced voltages without appreciably altering the electrical position of the rotor and to provide second polarity pulsed phases; measuring a second set of rise times for each of the second polarity induced voltages for a one-to-one correspondence with each of the second polarity pulsed phases to reach the threshold induced voltage level; determining a set of differences between the first set and the second set of rise times as measured in each of the measuring steps; determining which, if any, difference in said set of differences does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, for each said difference which does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, for each said difference which does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; and storing each sign of each said difference; and recalling and comparing each said sign of each said difference for each of the n phases with predetermined stored motor electrical position information to determine the initial position of the rotor.

Claim 49

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for determining an initial position of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing each phase of the n phases with a first polarity current to provide first polarity induced voltages without appreciably altering the electrical position of the rotor and to provide first polarity pulsed phases; measuring a first set of rise times for each of the first polarity induced voltages for a one-to-one correspondence with each of the first polarity pulsed phases to reach the threshold induced voltage level; pulsing each said phase of the n phases with a second polarity current to provide second polarity induced voltages without appreciably altering the electrical position of the rotor and to provide second polarity pulsed phases; measuring a second set of rise times for each of the second polarity induced voltages for a one-to-one correspondence with each of the second polarity pulsed phases to reach the threshold induced voltage level; determining a set of differences between the first set and the second set of rise times as measured in each of the measuring steps; determining which, if any, difference in said set of differences does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, for each said difference which does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, for each said difference which does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; and storing each sign of each said difference; and recalling and comparing each said sign of each said difference for each of the n phases with predetermined stored motor electrical position information to determine the initial position of the rotor.

Claim 50

The method of claim 38 wherein the step of tying is selected from the group consisting of tying high and tying low.

Claim 51

The method of claim 39 further comprising the step of: determining a duration and a polarity of at least one pulse for starting the motor in the predetermined direction of rotation, the duration of said pulse sufficient for moving the rotor up to but not passed an initially encountered commutation region.

Claim 52

The method of claim 40 further comprising the step of: accelerating the motor to resolve at a medium speed.

Claim 53

The method of claim 41 further comprising the steps of: accelerating the rotor from the medium speed to revolve at a nominal speed; and maintaining the rotor revolving at the nominal speed.

Claim 54

The method of claim 42 wherein n is equal to three.

Claim 55

The method of claim 42 wherein the first polarity current is negative polarity direct current, and the second polarity current is positive polarity direct current.

Claim 56

The method of claim 42 wherein the first polarity current is positive polarity direct current and the second polarity current is negative polarity direct current.

Claim 57

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with a first polarity current to provide a first polarity induced voltage without appreciably altering the electrical position of the rotor and to provide a first polarity pulsed phase; measuring a first rise time for the first polarity induced voltage for the first polarity pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with a second polarity current to provide a second polarity induced voltage without appreciably altering the electrical position of the rotor and to provide a second polarity pulsed phase; measuring a second rise time for the second polarity induced voltage for the second polarity pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining and storing any sign of the difference; determining if the difference is too small to resolve the electrical position of the rotor; determining and storing, if the difference is too small to resolve the electrical position of the rotor, a magnitude of one of the first and the second rise time associated with the difference; determining whether the magnitude does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, if the magnitude does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the magnitude does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference; and repeating the steps comprising the step of mapping until each of the n phases is processed; and recalling and comparing the sign of the difference plus the magnitude of an associated one of the first and the second rise time, if the electrical position is ambiguous with only the sign of the difference, with predetermined stored motor electrical position information to energize at least one of the n phases to start the motor in the predetermined direction of rotation.

Claim 58

In a brushless DC motor having n phases corresponding to phase windings arranged as a stator and a rotor for n an integer greater than zero, a method for starting the motor in a predetermined direction of rotation of the rotor, the method comprising the steps of: initializing a threshold induced voltage level; mapping electrical position of the rotor including the steps of: pulsing a phase of the n phases with a first polarity current to provide a first polarity induced voltage without appreciably altering the electrical position of the rotor and to provide a first polarity pulsed phase; measuring a first rise time for the first polarity induced voltage for the first polarity pulsed phase to reach the threshold induced voltage level; again pulsing the phase of the n phases but this time with a second polarity current to provide a second polarity induced voltage without appreciably altering the electrical position of the rotor and to provide a second polarity pulsed phase; measuring a second rise time for the second polarity induced voltage for the second polarity pulsed phase to reach the threshold induced voltage level; determining a difference between the first and the second rise time as measured in each of the measuring steps; determining and storing any sign of the difference; determining if the difference is too small to resolve the electrical position of the rotor; determining and storing, if the difference is too small to resolve the electrical position of the rotor, a magnitude of one of the first and the second rise time associated with the difference; determining whether the magnitude does not provide sufficient information to ultimately resolve the electrical position of the rotor; tying, if the magnitude does not provide sufficient information to resolve the electrical position of the rotor, one of the n phases not the phase currently being tested; retesting, if the magnitude does not provide sufficient information to resolve the electrical position of the rotor, by repeating the step of mapping; storing a sign of the difference; and repeating the steps comprising the step of mapping until each of the n phases is processed; and recalling and comparing the sign of the difference plus the magnitude of an associated one of the first and the second rise time, if the electrical position is ambiguous with only the sign of the difference, with predetermined stored motor electrical position information to energize at least one of the n phases to start the motor in the predetermined direction of rotation.