Bachelor/Semester/Master Theses

The electrification of construction machinery, such as excavators or dump trucks, has recently been gaining popularity due to numerous technical, economical, and ecological benefits. At HPE, concepts to replace hydraulic excavators with electrical counterparts are investigated. The excavator’s battery voltage can vary substantially around its nominal value (up to ±25%). To boost this voltage up to a constant DC-link voltage for a motor drive (with energy recuperation), a highly compact and efficient bidirectional boost converter is required. In this project, you will commission a prototype system of a given boost converter design. This task includes the PCB, the magnetic components (inductors), the cooling system and the implementation of converter control & safety functions in VHDL. Thereafter, you will test the system at multiple operating points. Finally, you will make improvements to the PCB and/or the inductive components for an improved prototype system based on your findings during testing.

Simon Beck, ETL F12, beck@hpe.ee.ethz.ch

25% Control 10% Hardware Design 10% Simulation 30% Testing 25% VHDL Coding

Interest and knowledge in power electronic systems, Interest and knowledge in hardware design, Working language: English/German

Dr. Jürgen Biela

Magnetic materials constitute inductors and transformers used in the manufacturing of power electronic converters, which enable the conversion of electrical energy. The magnetic material on which the project is focused is magnetic powder core, which is a mixture of magnetic particles homogeneously distributed into a non-magnetic material. As each particle is insulated from the others, the induced eddy currents are distributed within the particle itself. In this project, you will develop analytical models to describe the distribution of the induced eddy currents in particles with different shapes. The development of physics-based models that describe the losses in magnetic materials, such as the one proposed here, is part of a wider class of models that describe the power converters’ behaviour. These models are then implemented in Matlab, building a modelling architecture, and are essential for the virtual prototyping of power converters, which is a significant topic in power electronics. As a result, this project is linked to a relevant engineering problem.

Marco Cotti, ETL F11, cotti@hpe.ee.ethz.ch

50% Modelling 50% Theory

• Interest in power electronic systems and material science • Interest and knowledge in Electromagnetics, Working language: English

Dr. Jürgen Biela

At HPE, Wide Band Gap (WBG) semiconductor device models have been developed for SiC MOSFETs and GaN HEMTs. For an optimal converter design, accurate yet computationally efficient switching loss models of such semiconductor devices are needed. In this project, you will first derive and implement an analytical turn-off switching loss model for SiC MOSFETs in Matlab based on a publication. Then, you will simulate switching waveforms and calculate switching losses in LTspice. As a next step, you will validate and compare your implemented analytical model with both LTspice simulations and existing measurement results from an optimally designed PCB for a SiC Half-Bridge at different operating conditions. Finally, you will comprehensively evaluate the accuracy of the implemented model using both device characteristics from data sheets and those measured from a power device analyser at HPE.

Anliang Hu, ETL F11, hu@hpe.ee.ethz.ch

30% Theory 50% Implementation 10% Simulation 10% Testing

Interest in power electronics, knowledge in basic electric circuit theory

Dr. Jürgen Biela

The electrification of construction machinery, such as excavators or dump trucks, has recently been gaining popularity due to numerous technical, economical, and ecological benefits. Therefore, concepts to replace hydraulic excavators actuators with electric counterparts are investigated at HPE. To enable bidirectional power flow to such electric actuators, wireless power transmission (WPT) is employed. Thereby, the mechanical durability is increased compared to brush rings or external cables, while maintenance requirements are reduced. In this project, you will commission the prebuilt WPT converter hardware, which consists of the primary and secondary PCBs as well as the WPT transformer. After validating the basic functionality of the system (isolation, switching, V&I measurements, etc.), you will develop safety and control mechanisms in VHDL to enable the full operation of the converter. Finally, you will make adjustments to the PCBs and/or WPT transformer for an improved prototype system based on your findings during operation.

Simon Beck, ETL F12, beck@hpe.ee.ethz.ch

10% Control 10% Hardware Design 10% Simulation 35% Testing 35% VHDL Coding

Interest and knowledge in power electronic systems, Interest and knowledge in hardware design, Working language: English/German

Dr. Jürgen Biela

The electrification of construction machinery, such as excavators or dump trucks, has recently been gaining popularity due to numerous technical, economical, and ecological benefits. At HPE, concepts to replace hydraulic actuators with electrical counterparts are investigated. Wireless power and data transfer across a mechanical joint (e.g. of an excavator arm) enables nearly maintenance free operation of the joint. The data/communication channel needs to be immune to interference, capable of real-time communication, and reliable even in dirty environments, such as construction sites. Radio frequency (RF) communication has been identified as a promising option to establish such a communication channel. In this project, you will design a communication system with focus on the RF antenna and adapt it to a given joint geometry. You will use FEM tools to optimise the antenna and identify the most suitable RF frequency range considering available communication ICs. Finally, if time permits, you will build a prototype of the resulting RF communication system.

Simon Beck, ETL F12, beck@hpe.ee.ethz.ch

33% Hardware Design 33% Modelling 33% Simulation

Interest and knowledge in microwave/RF engineering, Interest in power electronic systems Working language: English/German

Dr. Jürgen Biela