Calculation of the Motor Torque of a rotating 2D model shown on the example of a Siemens Servo Motor 1FT6.

Initial Situation

Siemens Servo Motor 1FT6

This universal synchronous motor is used for many high-performance motion control applications. It uses permanent-magnets, has very small torque ripple  and an almost constant torque characteristic.

Picture: CAD Model

The motor we analyzed uses 36 nuts, 8 permanentmagnets, 4 poles.

In the first step our goal is to analyze torque over rotor angle. This can be done quite easy in 2D using the magnetostatic solutiontype.

Appropriate Method

2D Magnetostatic Analysis

In the NX Advanced Simulation preprocessor the mesh is created in 2D, material properties are assigned from the delivered library as well as currents as boundary conditions.

Picture: Resulting Flux Density

The analysis is performed as a step by step analysis, taking into account the rotation of the rotor and the harmonic behaviour of the currents.  

In the postprocessor a conturplot of the magnetic flux-density is shown. Also a video of the rotating motor can be displayed

Result

Torque over Time

The rotor is turning 90 degrees with a step size of 1 degree. We compute for the torque-curve under full load condition.

Picture: Resulting Torque

The computed torque is about 18 Nm what is close to the measurement.

Also the ripple is quite small