MOTOR WITH MAGNETIC SENSORS
Disclosed is an electric motor that includes a stator with a plurality of main poles, each of which includes a coil, and a rotor rotatable about an axis and having a magnet with magnetic poles in which N and S poles are alternating. The motor further includes a first sensor group of a plurality of magnetic sensors fixed relative to the stator, and a second sensor group of a plurality of magnetic sensors fixed relative to the stator. When operating the motor, the first sensor group can be selected so as to rotate the rotor in a first direction. The second sensor group can be selected so as to rotate the rotor in a second direction opposite to the first direction.
1 . A method of operating an electric motor, the method comprising:
providing an electric motor comprising:
a stator comprising a plurality of main poles, each of which comprises a coil,
a rotor rotatable about an axis and comprising a magnet, which comprises a plurality of magnetic poles in which N and S poles are alternating,
a first sensor group comprising a plurality of Hall effect sensors fixed relative to the stator, and
a second sensor group comprising a plurality of Hall effect sensors fixed relative to the stator;
selecting the first sensor group so as to detect a rotor position relative to the stator with the first sensor group;
switching current flow of the coils based at least in part on the rotor position detected by the first sensor group so as to rotate the rotor in a first direction;
selecting the second sensor group so as to detect a rotor position relative to the stator with the second sensor group; and
switching the current flow of the coils based at least in part on the rotor position detected by the second sensor group so as to rotate the rotor in a second direction opposite to the first direction.
2 . The method of claim 1 , wherein each sensor of the first and second sensor groups is configured to detect magnetic poles of the rotor.
3 . The method of claim 2 , wherein each sensor of the first sensor group is configured to detect the change of magnetic poles when the rotor rotates in the first direction.
4 . The method of claim 3 , wherein the current flow of one of the coils is synchronized with the change of the magnetic poles detected by one of the sensors of the first sensor group.
5 . The method of claim 3 , wherein each sensor of the first sensor group is configured to generate an alternating electric signal when the rotor rotates in the first direction.
6 . The method of claim 5 , wherein the current flow of one of the coils is synchronized with the alternating electric signal of one of the sensors of the first sensor group.
7 . The method of claim 2 , wherein each sensor of the second sensor group is configured to detect the change of magnetic poles when the rotor rotates in the second direction.
8 . The method of claim 1 , wherein the main poles comprises a first phase pole with a first phase coil and a second phase pole with a second phase coil, wherein the first sensor group comprises a first Hall effect sensor and a second Hall effect sensor, wherein the second sensor group comprises a third Hall effect sensor and a fourth Hall effect sensor, wherein the first and third sensors are configured to be used in switching the first phase coil, and wherein the second and fourth sensors are configured to be used in switching the second phase coil.
9 . The method of claim 8 , wherein the first and second sensors are configured to generate first and second alternating electric signals, respectively, when the rotor rotates in the first direction, wherein the current flow of the first phase coil is synchronized with the first alternating electric signal and the current flow of the second phase coil is synchronized with the second alternating electric signal when the rotor rotates in the first direction.
10 . The method of claim 8 , wherein the third and fourth sensors are configured to generate third and fourth alternating electric signals, respectively, when the rotor rotates in the second direction, wherein the current flow of the first phase coil is synchronized with the third alternating electric signal and the current flow of the second phase coil is synchronized with the fourth alternating electric signal when the rotor rotates in the second direction.
11 . The method of claim 8 , wherein the main poles further comprises a third phase pole with a third phase coil, wherein the first sensor group further comprises a fifth sensor and the second sensor group further comprises a sixth sensor, wherein the fifth and sixth sensors are configured to be used in switching the third phase coil.
12 . The method of claim 1 1 , wherein the fifth sensor is configured to generate a fifth alternating electric signal when the rotor rotates in the first direction, wherein the current flow of the third phase coil is synchronized with the fifth alternating electric signal.
13 . The method of claim 8 , wherein the first and second sensors are configured to generate first and second alternating electric signals, respectively, when the rotor rotates in the first direction, wherein the first and second sensors have a positional relationship with each other such that the first and second electric signals have a phase difference of about 90° from each other.
14 . The method of claim 13 , wherein the third and fourth sensors are configured to generate third and fourth alternating electric signals, respectively, when the rotor rotates in the second direction, wherein the third and fourth sensors have a positional relationship with each other such that the third and fourth electric signals have a phase difference of about 90 ° from each other.
15 . The method of claim 8 , wherein the first and third sensors have a positional relationship with each other such that, for a certain rotor position relative to the stator, the first sensor detects a magnetic pole of the rotor opposite to that detected by the third sensor.
16 . The method of claim 8 , wherein the first and third sensors have a positional relationship with each other such that, for substantially entire positions of the rotor relative to the stator, the first sensor detects a magnetic pole of the rotor opposite to that detected by the third sensor.
17 . The method of claim 8 , wherein the first, second, third and fourth sensors have their positional relationship with each other such that, for a first rotor position relative to the stator, the first and third sensors detect opposite magnetic poles of the rotor to each other and the second and fourth sensors are configured to detect opposite magnetic poles of the rotor to each other, and
wherein the first, second, third and fourth sensors further have their positional relationship such that, for a second rotor position different from the first rotor position, the first and third sensors detect opposite magnetic poles of the rotor to each other while the second and fourth sensors detect the same magnetic pole of the rotor.
18 . The method of claim 1 , wherein the stator comprises a plurality of auxiliary poles, each of which is positioned between two main poles.
19 . A method of operating an electric motor, the method comprising:
providing an electric motor comprising:
a stator comprising a plurality of main poles, each of which comprises a coil,
a rotor rotatable about an axis and comprising a magnet, which comprises a plurality of magnetic poles in which N and S poles are alternating,
a first sensor group comprising a plurality of magnetic sensors fixed relative to the stator, and
a second sensor group comprising a plurality of magnetic sensors fixed relative to the stator;
selecting the first sensor group so as to detect a rotor position relative to the stator;
switching current flow of the coils based at least in part on the rotor position detected by the first sensor group so as to rotate the rotor in a first direction;
selecting the second sensor group so as to detect a rotor position relative to the stator; and
switching the current flow of the coils based at least in part on the rotor position detected by the second sensor group so as to rotate the rotor in a second direction opposite to the first direction.
20 . An electric motor comprising:
a stator comprising a plurality of main poles, each of which comprises a coil;
a rotor rotatable about an axis and comprising a magnet, which comprises a plurality of magnetic poles in which N and S poles are alternating;
a first sensor group comprising a plurality of magnetic sensors fixed relative to the stator;
a second sensor group comprising a plurality of magnetic effect sensors fixed relative to the stator; and
an electric circuit configured to switch current flow of the coils based at least in part on the rotor's position detected by the first sensor group so as to rotate the rotor in a first direction and further configured to switch the current flow of the coils based at least in part on the rotor position detected by the second sensor group so as to rotate the rotor in a second direction opposite to the first direction.