Lab Affiliation(s):
Research Laboratory of Electronics
Post Doc Sponsor / Advisor:
David Perreault
Areas of Expertise:
  • Power Electronics
  • Energy Systems
  • Circuits and Systems
Date PhD Completed:
June, 2015
Expected End Date of Post Doctoral Position:
July 15, 2016

Minjie Chen

  • Post Doctoral

MIT Unit Affiliation: 

  • Electrical Engineering & Computer Science

Lab Affiliation(s): 

Research Laboratory of Electronics

Post Doc Sponsor / Advisor: 

David Perreault

Date PhD Completed: 

Jun, 2015

Top 3 Areas of Expertise: 

Power Electronics
Energy Systems
Circuits and Systems

Personal Statement: 

I received my Ph.D. degree in June 2015 from the Department of Electrical Engineering and Computer Science at Massachusetts Institute of Technology, where I am currently a Postdoctoral Associate. My advisor is Prof. David J. Perreault and Prof. Khurram K. Afridi. My research is in the area of power electronics, with a focus on renewable energy, grid-interface power electronics, and high performance power management systems.

Expected End Date of Post Doctoral Position: 

July 15, 2016


Research Projects: 

High-frequency, high-efficiency, miniaturized grid-interface power electronics systems
Hybrid switched-capacitor/magnetics power conversion architecture
A systematic approach to modeling impedances and current distribution in planar magnetics
A multilevel energy bu er and voltage modulator for solar microinverters
Stacked switched-capacitor energy buffer architecture
Superconducting nanowire electro-thermal modeling illustrated via SPICE (with Prof. Karl Berggren)
A 20 mV thermalvoltaic energy harvesting system based on Meissner oscillator (with Dr. Dennis Buss)
SSC energy bu er for submarine modular multilevel converter (with Prof. Li Ran)

Thesis Title: 

Merged Multi-Stage Power Conversion: A Hybrid Switched-Capacitor/Magnetics Approach

Thesis Abstract: 

Emerging applications of power electronics introduce challenging design requirements. Increasing the system complexity in appropriate ways can bring many advantages, yielding reduced system volume and/or improved system performance. This thesis explores new circuit design techniques that can leverage the advantages of merged multi-stage power conversion through a hybrid switched-capacitor/magnetics approach. Multiple circuits and system aspects of this approach are investigated in this thesis.

A 70 W grid-interfaced solar micro-inverter with a multilevel energy buffer and voltage modulator is developed to demonstrate the advantages of a merged multi-stage system in dc-ac applications. By synthesizing a multilevel voltage in pace with the ac grid voltage using the energy buffer, the wide operation range of the inverter stage is compressed, leading to a significantly improved overall system performance.

A high-power-density wide-input-voltage-range isolated dc-dc converter with a MultiTrack power conversion architecture is also investigated. The MultiTrack architecture delivers power in multiple voltage domains and current tracks. It incorporates multiple distributed circuit cells, and benefits from the way they are merged together. By changing the use of multiple cells according to the system operating condition, the overall device utilization of the system is enhanced, leading to significantly improved power density as compared to conventional designs while maintaining high efficiency. The prototype 18 V--80 V input, 5 V output, 75 W isolated dc-dc converter achieves 453.7 W/inch$^3$ power density, which is 3x higher than the best commercial product presently available. It maintains high efficiency across a wide (>4:1) input voltage range, and has a peak efficiency of 91.3%.

Advanced magnetics structures are an enabling technique on the path to improved power conversion. This thesis developed a systematic approach to modeling impedances and current distribution in planar magnetics. It captures electromagnetic coupling relationships using an analytical lumped circuit model, and enables rapid evaluation of planar magnetics designs. The effectiveness of the model is verified by numerical methods and experimental measurements. A software package -- M2Spice -- that can rapidly convert design information into SPICE netlists has been developed and is being utilized in many real designs.

Contact Information: