Electro-thermal topology optimization of an electric machine by the topological derivative considering drive cycles

TL;DR

This paper presents a method for optimizing the rotor topology of a 2D permanent magnet synchronous machine to maximize efficiency by considering electromagnetic, thermal, and mechanical constraints using topological derivatives.

Contribution

It introduces a coupled electromagnetic-thermal-structural optimization framework with topological derivatives for rotor design considering drive cycle conditions.

Findings

The optimized rotor design improves efficiency under drive cycle conditions.

Thermal and mechanical constraints effectively prevent damage and failure.

High-speed operation constraints significantly influence the topology optimization.

Abstract

We consider a 2d permanent magnet synchronous machine operating in a sequence of static operating points coming from a drive cycle. We aim to find a rotor design which maximizes the efficiency defined as the quotient of input and output energy considering Joule losses in the stator and eddy current losses in the permanent magnets. A coupled electromagnetic-thermal analysis of the rotor considers the eddy current losses as heat source and adds a temperature constraint to avoid damage of the permanent magnets. Additionally we impose Von-Mises stress constraints to maintain the mechanical integrity of the design. To solve the resulting free form topology optimization problem we use a level set description of the design and the topological derivative as sensitivity information. We show the effect of these constraints at very high speeds which is a trend in recent machine development.