# Ansys Maxwell: Transient generator simulation torque fluctuation

• piyushverma
In summary, the conversation discusses the design and simulation setup of an axial flux generator with 2 rotors and 1 stator, 6 pole pairs, and 9 coils. The windings are connected in a star configuration and the rotors are set to rotate at a constant speed of 1000RPM. The results for output voltages are satisfactory, but there is confusion about the torque curve, which switches sign and has peaks when the stator material is changed from electrical steel to air. The reason for this torque is unclear, as there is no core or load connected. The possibility of the poles acting as a capacitor and the assumption of ideal coils are also discussed as potential explanations.
piyushverma
TL;DR Summary
while simulation for a PM axial flux generator at no load 1000RPM, shows moving torque fluctuating between -0.7 to 0.7 Nm, which should have been 0, as there is no load attached and it is coreless design so no cogging torque as well. Need someone to help me out.
I am working on an axial flux generator design, I consisits of 2 rotors and one stator, there are 6 pole pairs and 9 coils. Here is my simulation setup

The three phase windings are connected in star configuration through Maxwell circuit.
I created two bands enclosing each rotor and then united them to assign a single band for both rotor which is set to rotational motion at 1000RPM constant. I am getting satisfactory results for output voltages, what I don't understand is this torque curve

currently the stator material is air ( I switched to air after setting it initially to electrical steel laminated, which resulted in 2Nm peaks in torque).
I don't understand the reason for this torque as there is no core so no cogging torque and also there is no load connected.
I am stuck, Kindly help :(

Delta2
Any generator that relies on motional EMF has a very low current when rotating even in the presence of no external load.

On second thought it puzzles me that the Torque switches sign, according to my explanation it should 've been only negative (or only positive, depending how you define positive or negative here).

Something else, the coils are assumed to be ideal or have ohmic resistance? I think I might be able to explain this if the coils are not ideal.

Last edited:
The poles of the generator act as a capacitor that serves as some sort of external load. Depending on how you have setup your simulation software, it might be able to "see" this capacitor and include it in an implicit way in its calculations.

## What is Ansys Maxwell?

Ansys Maxwell is a software program used for electromagnetic field simulation. It allows users to model and analyze various electrical and electromechanical systems.

## What is a transient generator simulation?

A transient generator simulation is a type of simulation that models the behavior of an electrical system over time. It takes into account factors such as voltage fluctuations, current surges, and other transient effects that can occur in a system.

## What is torque fluctuation?

Torque fluctuation is the variation in the amount of force or rotational energy applied to a system. In the context of Ansys Maxwell, it refers to the fluctuation in torque that occurs in an electromagnetic system due to transient effects.

## Why is it important to simulate torque fluctuation in Ansys Maxwell?

Simulating torque fluctuation in Ansys Maxwell allows engineers to accurately predict the performance of an electromagnetic system. It can help identify potential issues and optimize the design to improve efficiency and reduce potential failures.

## What are some applications of Ansys Maxwell's transient generator simulation for torque fluctuation?

Ansys Maxwell's transient generator simulation for torque fluctuation can be used in a variety of industries, including automotive, aerospace, and renewable energy. It can be applied to systems such as motors, generators, transformers, and more, to improve their design and performance.

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