REDUCTION OF THE TORQUE RIPPLE IN SYNCHRONOUS RELUCTANCE MACHINES
A synschronous reluctance motor is a syncrounous machine, which typically consists of a rotor and a stator. The stator is characterized by a certain number of slots and a certain winding topology, which is needed to create a nearly sinusuoidal megnatic field distribution. The non-excited rotor consists of a geometrical arrangement of ais gaps. Due to different reluctances in the rotor, this machine type produces electromagnetic torque as soon as a magnetic field - caused by stator windings - occurs. The application of synchronous reluctance machines is limited by the produced torque ripple. It is established, that the geometry of the rotor flux barriers can be crucial for the torque ripple reducti- on. Different rotor designs have been proposed to meet this challenge. But more often than not, the knownmethodshavedisadvantageswith respect to either the mean output torque or the machine’s manufacturing process.
This invention consists of a particularly advantageous rotor gaps arrangement of a reluctance ma- chine, which minimizes the torque ripple. In contrast to former solutions, the newly developed arran- gement allows an improvement for all stator and rotor geometries. Depending on initial machine design - number of stator slots, concentrated or distributed winding, number and form of rotor bar- riers - torque ripples can be reduced by 38-54%. Unlike other solutions available on the market, the average output torque remains nearly constant (1-2% decrease) and the manufacturing process is the same as for standard reluctance machines.
The invention can be used for a wide range of applications, where and electric motor or generator is implemented. Some examples are the electromobility, energy generation (wind energy), and pumping systems.
(up) torque of a synchronous reluctance machine with a 12-teeth-stator and 4-poles-rotor (12/4-SynRM) either according to the standard arrangment (blue line) or according to the arrangement developed in the frame of the invention (red line); the torque ripple is reduced by the 38% , while the average torque (red dashed line) is only 2% smaller in comparison with a standard machine (blue dashed line). (low) torque of a synchronous reluctance machine with a 42-teeth-stator and 14-poles-rotor (42/14-SynRM) either according to the standard arrangment (blue line) or according to the arrangement developed in the frame of the invention (red line); the torque ripple is reduced by the 54% , while the average torque (red dashed line) is only 1% smaller in comparison with a standard machine (blue dashed line) .