Intelligent Power Modules

High power density and high switching frequencies impose stringent requirements on packaging technologies. By appropriate approaches such as 3D packaging, parasitic effects that are caused by packages, substrates and layouts, can be systematically influenced and reduced. Due to compact hot spots, heat spreading and heat dissipation are more important than ever.

Open student theses

Due to ever increasing power densities, number of devices and the use of wide-bandgap semiconductors, power electronic systems are getting more complex and compact. To still achieve a maximum efficiency, all solutions of the (discrete) solution space must be investigated. The solution space is defined by e.g. suitable semiconductors and passives or the PCB-design.

To map this solution space, the aid of computer-based methods is necessary, which are calculating the optimal point of the so called pareto-front.

Goal of this thesis is to implement a workflow for such a pareto-front optimization with a multi-dimensional simulation for a compact DC/DC-converter and, if applicable, to construct and characterize this converter.

Time plan

  • Literature research (10%)
  • Implementation multi-domain optimization (50%)
  • Setup and characterization of the converter (25%)
  • Written thesis & talk (20%)

Preliminary experience

  • Experience in 3D-FEM helpful
  • Knowledge in power electronics
  • Good knowledge of MATLAB or similar

 

Contact: Dominik Koch

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Blockdiagramm MTT Sat-Challenge

ILH takes part at the international MTT Sat-Challenge for students and after-graduates, with the goal of the development of novel high-frequency hardware (RF) for CubeSats. The ILH convinced with the idea of combining a gallium nitride (GaN) power amplifier for W-band (75-100 GHz) with a variable and monolithic integrated GaN DC/DC power supply, to achieve a more compact and efficient amplifier.

In addition the amplifier should be improved by digital pre-distortion and with the aid of a power detector at the output of the amplifier, an intelligent power module should be evaluated.

The ILH is offering several topics for a student thesis in the frame of this challenge:

Topics:

PE

  • Layout design and simulation of an integrated DC/DC converter
  • Reduction of noise of a GaN DC/DC for a SSPA supply
  • Control implementation for a GaN DC/DC on a space-ready micro-controller

mmW

  • Simulation and layout of a power detector topologies incl. couplers in a GaN-technology
  • Implementing and extension of digital pre-distortion for an E-band amplifier
  • Investigation of efficiency enhancement methods for a power amplifier in E-Band
  • Investigation of analog pre-distortion technologies for a mmW amplifier
  • Influence of noise in the DC supply on a mmW amplifier

 

Contact PE: Dominik Koch

Contact mmW: Benjamin Schoch

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One of the main objectives in the development of power electronic circuits is to increase efficiency and thus reduce energy losses. This allows a smaller dimensioned cooling system and reduced space requirement of components, which leads to material savings and in the end to cost reduction and a resource-saving production of the power electronic assembly.

The topic of this thesis is to identify the limits in which Peltier elements in power electronic circuits can be usefully applied for energy recovery.

In this context it has to be investigated under which electrical and thermal conditions the Peltier element has to be operated, at which point in the heat dissipation path it can be best integrated and how the generated electrical energy can be coupled into the circuit of the gate control.

Topics:

  • Peltier elements:
    • Simulation capabilities
    • Energy recovery with TEGs
    • Limits?
  • Losses in gate driver circuits
  • Possibility of energy recovery into the gate driver circuit
  • Circuit design for efficiency analysis

Contact: Jan Hückelheim

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Im Rahmen der Forschung zur Leistungselektronik in der Elektromobilität ist die Optimierung der Leistungsdichte die wesentliche Maßnahme bezüglich verbesserter Nutzerfreundlichkeit, erhöhter Effizienz und verringerter Kosten. Die Leistungsdichte von Batterie-Ladegeräten in passiv gekühlten Gehäusen ist weitestgehend durch die maximale Berührtemperatur an der Oberfläche limitiert. Der Betrieb bei  höheren Leistungen mit mehr Verlusten führt nach einer thermischen Erwärmungsphase zu einer Überschreitung dieser maximalen Temperatur und macht eine Drosselung der Leistung oder eine Vergrößerung der Gehäuseoberfläche nötig.

Durch den Einsatz von Wärmespeichern kann diese Erwärmungsphase jedoch um einige Minuten verlängert werden und eine erhöhte Ladeleistung und somit Leistungsdichte zu Beginn des Ladevorgangs ermöglicht werden. Besonders geeignet scheinen hierbei PCMs, welche eine besonders hohe Wärmekapazität aufweisen. In dieser Arbeit sollen PCMs für den Einsatz als Latentwärmespeicher in der Leistungselektronik untersucht werden.

Inhalte und Ziele

  • Bestimmung geeigneter PCMs zur Wärmespeicherung in der Leistungselektronik
  • Entwurf von Regelkonzepten zur optimalen Ausnutzung von Erwärmungsphase und Wärmespeicher
  • Hardwareaufbau von Leistungselektronik mit und ohne PCMs zum direkten Vergleich der Kühlkonzepte
  • Modellierung des thermischen Aufbaus mittels thermischer FEM-Fluid-Simulation

Kontakt: Julian Weimer

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In der Leistungselektronik beeinflussen mehrere physikalische Domänen die Leistung eines leistungselektronischen Geräts. Die Simulation von Leistungsmodulen wird derzeit mit thermischen, elektromagnetischen und mechanischen eigenständigen Finite-Elemente-Simulationen durchgeführt, wobei die Kopplung mehrerer Domänen manuell und in vereinfachter Form berücksichtigt wird. Um einen höheren Optimierungsgrad zu erreichen, sind schnelle und hochgenaue Multi-Domain-Simulationen notwendig.

Inhalt und Ziele

  • Entwurf eines elektrothermischen Simulationsmodells für eine GaN-Halbbrücke hoher Leistungsdichte
  • Simulationsverifizierung durch thermische und elektrische Messungen
  • Quantifizierung des möglichen Nutzens eines multiphysikalischen Simulationsansatzes
  • Ansätze zur Layout-Optimierung

Kontakt: Julian Weimer

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Trotz des Einsatzes von immer fortschrittlicheren Halbleitern in der Leistungselektronik lassen sich elektrische Verluste kaum vermeiden. Um dennoch hohe Leistungsdichten zu erreichen ist ein leistungsfähiges und zuverlässiges Kühlsystem entscheidend. Dies ist insbesondere kritisch für passiv gekühlte Systeme, welche den Einsatz innovativer Kühlsysteme erforderlich macht.

Zur Vermeidung kritischer Hotspots werden zur Kühlung von CPUs in Laptops und Smartphones immer häufiger Heat Pipes, Vapor Chambers und pyrolytische Graphitbögen (PGS) verwendet. Neben diesen neuen Konzepten und Materialien lassen sich zudem durch 3D strukturierte Materialwechsel der Wärmefluss basierend auf thermischen 3D FEM Simulationen gezielt steuern. Ziel dieser Arbeit ist die thermische Topologie Optimierung für ein hochkompaktes Ladegerät für homogenere Temperaturverteilungen und somit höhere Leistungsdichten unter verwendung innovativer Konzepte und Materialien.

Inhalt und Ziele

  • Thermische 3D FEM Simulation
  • Topologie Optimierung des Wärmeflusses zur Reduktion von Hotspots in einem hochkompakten Ladegerät
  • Vergleich verschiedener Materialkonzepte
  • Thermische und Elektrische Vermessung

Kontakt: Julian Weimer

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Abstract

To achieve a maximum power density, typically a high switching frequency and soft-switched transitions (ZVS) are applied in power electronics. The dead-time is typically a few several of tens nanoseconds for GaN-HEMTs and has to be adjusted for each working point individually.

Goal of this work is the implementation of such an adaptive gate-drive for GaN-HEMTs to automatically improve the dead-time to achieve minimal losses. With the help of a “Zero-Voltage Switching Detector (ZVSD)” a regulation of the optimum dead-time should be done automatically for each working point and therefore replace the manual setting. In this frame several different approaches (for example slope-sensing) should be evaluated regarding their performance.

Timetable

  • Familiarization & literature search (15%)
  • Simulation and design of a suitable detection circuit (30%)
  • Assembly and measurements (30%)
  • Written thesis & presentation (25%)

Previous knowledge:

  • Circuit/layout design in Altium
  • Experience in practical lab work
  • Experience in circuit simulation

 

Contact: Dominik Koch

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Abstract

Various filters are used to comply with limits for the emission of electromagnetic interference from a charger. These are differentiated into several types of interference mechanisms, each of which has a different physical origin and characteristics:

On the one hand, there are conducted emissions, which spread over the connecting cables (towards the mains or output) and are mostly found in the low frequency range. On the other hand, radiated emissions play a role at higher frequencies and are more difficult to filter due to their local occurrence.

In this work, primarily the conducted interference of a PFC stage (AC/DC) shall be predicted by means of simulations and corresponding filters (filter, common- and differential choke) shall be designed.

Timetable

  • Familiarization & literature research (15%)
  • Simulation of the charger structure (25%)
  • Design of suitable filters (25%)
  • Construction and measurement (15%)
  • Essay & Talk (20%)

Previous knowledge:

  • Experiences in Keysight ADS o. CST benefitial
  • Knowledge in high frequency technology & power electronics

Contact: Dominik Koch

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In high-frequent switching converter passive components (inductances, capacitances and transformers) are playing a major role, since their losses are often higher than the ones from the active components. Especially the estimation of these losses is difficult, since there is no efficient method to characterize the losses at high frequencies. Also the modelling of core materials at high frequencies and a wide power area is complex.

Because of these reasons in this work a design-flow should be developed, which allows to simulate and model inductances and transformers. In a first step different physical models (e.g. litz-wire) should be connected with magnetostatic and full-wave simulations. Afterwards a conventional transformer should be simulated and with the gained experience a planar transformer should be designed and optimized. If necessary some measurements with a NWA will support the simulations.

Timetable:

  • Familiarization & literature search(10 %)
  • Simulation and modelling of a transformer (25 %)
  • Design and simulation of a planar transformer (25 %)
  • Measurement of transformer (optional 20 %)
  • Written thesis & presentation (20 %)

Previous knowledge:

  • 3D-FEM simulation in CST
  • Knowledge of magnetic components and their loss mechanisms
  • Practical experience

 

Contact: Dominik Koch

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This image shows Benjamin Schoch
M.Sc.

Benjamin Schoch

Research Assistant

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