Motor, motor control method and motor control device

1. A motor comprising:

a two-layer rotor including an A-phase rotor and a B-phase rotor that are stacked together, wherein

the A-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores, and

the B-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores;

a two-layer stator including an A-phase stator and a B-phase stator that are stacked together, wherein

the A-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and an A-phase winding, which is located between the two stator cores, and

the B-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and a B-phase winding, which is located between the two stator cores; and

a control unit that controls an A-phase input voltage that is applied to the A-phase winding and a B-phase input voltage that is applied to the B-phase winding, wherein

the A-phase stator and the A-phase rotor are arranged relative to the B-phase stator and the B-phase rotor at an electrical angle of 90 degrees, and

the control unit advances an angular phase of the A-phase input voltage from its basic voltage waveform and an angular phase of the B-phase input voltage from its basic voltage waveform and sets an excitation width to 180 degrees or less.

2. A method for controlling a motor, wherein the motor includes

a two-layer rotor including an A-phase rotor and a B-phase rotor that are stacked together, wherein

the A-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores, and

the B-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores;

a two-layer stator including an A-phase stator and a B-phase stator that are stacked together, wherein

the A-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and an A-phase winding, which is located between the two stator cores, and

the B-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and a B-phase winding, which is located between the two stator cores, wherein the A-phase stator and the A-phase rotor are arranged relative to the B-phase stator and the B-phase rotor at an electrical angle of 90 degrees;

the method comprising:

applying A-phase input voltage to the A-phase winding;

applying B-phase input voltage to the B-phase winding; and

setting a phase angle of each of the A-phase input voltage and the B-phase input voltage that is advanced by 24 to 42 degrees from a corresponding basic voltage waveform and setting an excitation width of the A-phase input voltage and the B-phase input voltage to 150 to 170 degrees.

3. A method for controlling a motor, wherein the motor includes

a two-layer rotor including an A-phase rotor and a B-phase rotor that are stacked together, wherein

the A-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores, and

the B-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores;

a two-layer stator including an A-phase stator and a B-phase stator that are stacked together, wherein

the A-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and an A-phase winding, which is located between the two stator cores, and

the B-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and a B-phase winding, which is located between the two stator cores, wherein the A-phase stator and the A-phase rotor are arranged relative to the B-phase stator and the B-phase rotor at an electrical angle of 90 degrees;

the method comprising:

applying A-phase input voltage to the A-phase winding;

applying B-phase input voltage to the B-phase winding; and

setting a phase angle of each of the A-phase input voltage and the B-phase input voltage that is advanced by 0 to 36 degrees (0 degrees exclusive) from a corresponding basic voltage waveform and setting an excitation width of the A-phase input voltage and the B-phase input voltage to 155 to 180 degrees.

4. A method for controlling a motor, wherein the motor includes

a two-layer rotor including an A-phase rotor and a B-phase rotor that are stacked together, wherein

the A-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores, and

the B-phase rotor includes two rotor cores, each including claw poles arranged at equal angular intervals, and a field magnet, which is located between the two rotor cores;

a two-layer stator including an A-phase stator and a B-phase stator that are stacked together, wherein

the A-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and an A-phase winding, which is located between the two stator cores, and

the B-phase stator includes two stator cores, each including claw poles arranged at equal angular intervals, and a B-phase winding, which is located between the two stator cores, wherein the A-phase stator and the A-phase rotor are arranged relative to the B-phase stator and the B-phase rotor at an electrical angle of 90 degrees;

the method comprising:

applying A-phase input voltage to the A-phase winding;

applying B-phase input voltage to the B-phase winding; and

setting a phase angle of each of the A-phase input voltage and the B-phase input voltage that is advanced by 24 to 36 degrees from a corresponding basic voltage waveform and setting an excitation width of the A-phase input voltage and the B-phase input voltage to 155 to 170 degrees.

5. A motor controller that performs the method for controlling a motor according to claim 2 , wherein the motor controller is configured to control the motor by generating the A-phase input voltage and the B-phase input voltage set by the method.

6. A motor comprising:

a stator including two stator units arranged in an axial direction, wherein the stator units each include

two stator cores, each including claw poles arranged in a circumferential direction, and

a winding located between the stator cores in the axial direction; and

a housing that accommodates the stator, wherein

the housing includes a first case and a second case that are coupled together,

one of the stator units is fixed to the first case,

the other one of the stator units is fixed to the second case, and

in a state in which the first and second cases are coupled together, a clearance exists between the two stator units in the axial direction.

7. The motor according to claim 6 , wherein:

the first and second cases each include a case body, which accommodates the corresponding stator unit, and a flange, which extends from an open end of the case body in a radial direction; and

the flange of the first case is fixed to the flange of the second case by a screw.

8. The motor according to claim 7 , wherein

the flange of at least one of the first and second cases includes a hole through which the screw is inserted, and

the hole is an elongated hole extending in the circumferential direction.

9. The motor according to claim 6 , wherein

the first case includes a projection that projects in the axial direction,

the second case includes a recess that is recessed in the axial direction, and

the projection and the recess are fitted together so that the first case and the second case are engaged with each other in the circumferential direction.

10. The motor according to claim 6 , wherein the first and second cases each include a positioning portion for positioning the accommodated stator unit in the axial direction.

11. A motor comprising:

a stator including stator units that are arranged in an axial direction, wherein the stator units each include a first stator core, a second stator core, and a winding located between the first stator core and the second stator core, wherein the first stator core and the second stator core each include a claw pole, and the claw pole includes a radially-extending portion that extends in a radial direction and a pole portion that extends from a distal end of the radially-extending portion in the axial direction;

a rotor including rotor units that are arranged in the axial direction, wherein the number of the rotor units is the same as the number of the stator units, and the rotor units each include a permanent magnet opposing the pole portion;

a sensor located between the permanent magnets in the axial direction, wherein the sensor detects magnetic flux of the permanent magnets.

12. The motor according to claim 11 , wherein the sensor is arranged within a circumferential angular range between the pole portions that are adjacent to each other in the circumferential direction in the stator unit corresponding to the permanent magnet detected by the sensor.

13. The motor according to claim 11 , further comprising a board located between the stator units in the axial direction, wherein the sensor is arranged on the board.

14. The motor according to claim 13 , wherein the board includes a drive circuit that supplies drive current to the winding.

15. The motor according to claim 11 , wherein

the sensor includes a detection surface, and

the sensor is arranged so that the detection surface is orthogonal to a circumferential direction.