Three-phase synchronous machine having a permanent magnet rotor with an induction cage
The aim of the invention is to achieve a high torque yield in synchronous machines excited by permanent magnets. Said aim is achieved by using subharmonic air gap fields. The rotor comprises an induction cage as well as permanent magnets. The number of winding holes of the stator is greater than q=0.5. The number of poles of the rotor is greater than the base number of poles of the air gap field produced by the windings.
1. A three-phase synchronous machine, comprising
a stator having a winding system which has a fractional-slot winding with q≦0.5, wherein q is defined as a number of stator slots per rotor pole per phase, and
a rotor having permanent magnets and an induction cage for asynchronous use of subharmonic airgap fields, wherein a number of rotor poles is greater than a basic number of poles of an airgap field which is produced by the winding system of the stator.
2. The synchronous machine as claimed in claim 1 , wherein the winding system of the stator has individual tooth-wound coils.
3. The synchronous machine as claimed in claim 1 , wherein the permanent magnets of the rotor are arranged in a flux concentration direction.
4. The synchronous machine as claimed in claim 1 , wherein the induction cage of the rotor is a symmetrical induction cage, with a pole pitch of the permanent magnets representing a symmetry unit.
5. The synchronous machine as claimed in claim 4 , wherein the permanent magnets and the induction cage are arranged radially one above the other.
6. The synchronous machine as claimed in claim 4 , wherein the induction cage is produced as a die-casting.
7. The synchronous machine as claimed in claim 4 , wherein the induction cage is formed from braided conductors.
8. The synchronous machine as claimed in claim 1 , wherein the stator has a basic number of poles 2p GS and a synchronous number of useful poles 2p Ns , wherein 2p Ns ≧4×2p GS .
9. Use of a synchronous machine as claimed in claim 1 in a traction drive or production machine.
10. The synchronous machine as claimed in claim 4 , wherein the permanent magnets and the induction cage are arranged axially alongside one another.
11. The synchronous machine as claimed in claim 6 , wherein the die casting is made of copper.
12. The synchronous machine as claimed in claim 6 , wherein the die casting is made of aluminum.
13. The synchronous machine as claimed in claim 8 , wherein current is induced in the induction coil by an asynchronous number of poles which is defined by 2p Na ≧2p GS .
14. The synchronous machine as claimed in claim 8 , wherein a ratio of a coil width τ Sp to a pole pitch τ p of the permanent magnets is 2.66≦τ Sp /τ p .