Power tool with permanent magnet synchronous reluctance machine

1. A power tool comprising:

a housing;

a motor assembly positioned within the housing, the motor assembly including:

a stator with winding slots that receive stator windings, and

a rotor including a rotor body with a first slot positioned a first distance from a center of the rotor body and a second slot positioned a second distance from the center of the rotor body, the first slot and the second slot are each curved about a common point;

wherein the rotor further includes a first magnet positioned within the first slot and a second magnet positioned within the second slot; and

wherein the first magnet spans within a range of approximately 50% to 56% of the first slot and the second magnet spans within a range of approximately 33% to 39% of the second slot.

2. The power tool of claim 1 , wherein the common point is positioned outside of the rotor body.

3. The power tool of claim 1 , wherein:

a first dimension is measured between a first end of the first slot and an outer circumferential surface of the rotor body;

a second dimension is measured between a second end of the first slot and the outer circumferential surface of the rotor body; and

the second dimension is equal to the first dimension.

4. The power tool of claim 1 , wherein:

a first dimension is measured between an end of the first slot and an outer circumferential surface of the rotor body;

a second dimension is measured between an end of the second slot and the outer circumferential surface of the rotor body; and

the second dimension is equal to the first dimension.

5. The power tool of claim 1 , wherein the rotor further includes a third slot positioned a third distance from the center of the rotor body, the third slot curved about the common point; and a third magnet positioned within the third slot.

6. The power tool of claim 5 , wherein the third magnet spans within a range of approximately 35% to 41% of a third slot.

7. The power tool of claim 5 , wherein the first magnet spans approximately 53% of the first slot, the second magnet spans approximately 36% of the second slot, and the third magnet spans approximately 38% of the third slot.

8. The power tool of claim 1 , wherein the motor is configured to drive a cyclical load.

9. The power tool of claim 1 , wherein the motor provides more startup torque than a brushless DC motor with a same package size and provides a higher no-load speed than the brushless DC motor with the same package size.

10. The power tool of claim 1 , further comprising a tool element and wherein the tool element is driven by the motor.

11. The power tool of claim 1 , wherein the stator includes at least twenty-four slots and the rotor is a 4-pole rotor.

12. The power tool of claim 1 , wherein a power output of the power tool is at least 500 Watts at an efficiency of at least 40% for a torque output of 2.0 Newton-meters or greater.

13. A power tool comprising:

a housing;

a permanent magnet synchronous reluctance machine positioned within the housing, the permanent magnet synchronous reluctance machine including a stator with stator windings and a rotor with a plurality of slots and a magnet positioned within each of the plurality of slots; and

a tool element driven by the permanent magnet synchronous reluctance machine;

wherein the plurality of slots are curved, and

wherein the magnet within at least one of the plurality of slots spans between approximately 33% and 39% of the slot.

14. The power tool of claim 13 , wherein the permanent magnet synchronous reluctance machine provides more startup torque than a brushless DC motor with a same package size and provides higher no-load speed than the brushless DC motor with the same package size.

15. The power tool of claim 13 , wherein the permanent magnet synchronous reluctance machine includes at least twenty-four winding slots formed in the stator and the rotor includes at least four poles.

16. The power tool of claim 13 , wherein a power output of the power tool is at least 500 Watts at an efficiency of at least 40% for a torque output of 2.0 Newton-meters or greater.

17. A motor assembly for a power tool, the motor assembly comprising:

a stator with winding slots that receive stator windings; and

a rotor including a rotor body with a first slot positioned a first distance from a center of the rotor body and a second slot positioned a second distance from the center of the rotor body; the first slot and the second slot are each curved about a common point;

wherein the rotor further includes a first magnet positioned within the first slot and a second magnet positioned within the second slot, and

wherein the first magnet spans within a range of approximately 50% to 56% of the first slot and the second magnet spans within a range of approximately 33% to 39% of the second slot.

18. The motor assembly of claim 17 , wherein the common point is positioned outside of the rotor body.

19. The motor assembly of claim 17 , wherein the motor is configured to drive a cyclical load, and wherein the motor provides more startup torque than a brushless DC motor with a same package size and provides a higher no-load speed than the brushless DC motor with the same package size.

20. The motor assembly of claim 17 , wherein a power output of the motor is at least 500 Watts at an efficiency of at least 40% for a torque output of 2.0 Newton-meters or greater.

21. The power tool of claim 17 , wherein the rotor further includes a third slot positioned a third distance from the center of the rotor body, the third slot being curved about the common point, and a third magnet positioned within the third slot, wherein the third magnet spans within a range of approximately 35% to 41% of a third slot.