Examenspresentation av Shijie Zhang och Pranav Katta

Examinator: Torbjörn Thiringer
Conducted at China Euro Vehicle Technology AB supervised by Sepideh Amirpour
Opponent: Shaurya Sharma, Henrik Zander

Abstract
The quest for increased efficiency for an electrified vehicle propulsion system has led to the adoption of a fast-switching Wide Band Gap (WBG) motor drive. As research continues to focus on improving energy efficiency, the necessity arises to model, simulate and study the power losses for these drive systems.

The proposed work in this thesis presents a comprehensive investigation into the overall efficiency of an electric drive system employed by variable switching frequency for sinusoidal pulse-width modulation (SPWM) over selected operating conditions. Using ANSYS software tools, a model of an interior permanent magnet synchronous machine (IPMSM), a 3-phase inverter circuit, and a control system are developed. A preliminary study is carried out to compare the finite element analysis and the numerical calculations of the fundamental losses in the IPMSM with a sinusoidal power supply. The results show the different control strategies that can be implemented, with the maximum torque per ampere (MTPA) method identified as ideal for the analysis.

The process is then repeated where the power is supplied through an SPWM-controlled 3-phase inverter operating under the same set of conditions. The inverter-motor losses are obtained for different switching frequencies at each tested operating point in the speed-torque envelope. The total energy efficiency of the inverter circuit and motor is determined for each operating point and switching frequency. Finally, the analysis produces an optimal switching frequency map such that the drive system is most efficient.

Welcome!

Shijie, Pranav and Torbjörn