Current Research

My group focuses on reducing carbon footprint and promoting the sustainability of energy conversion systems. About 45% of the total global electricity consumption flows through electric drive systems (EDS) including electric machines and their drives. To curb carbon emissions from fossil fuels in the near term, we are ramping up the usage of electric machines and power electronics (in transportation electrification, 4th industrial revolution, renewable energy, future power grid, etc.) and there will be supply issues on the materials used to produce them in the long run. For example, converting all on-road vehicles into battery electric vehicles would consume ~ 1.9M tons of neodymium, constituting 24% of the world reserve. How to design, operate, maintain, and recycle energy conversion system from a life-cycle perspective to enable long-term sustainability is critical to the prosperity of our planet earth. My group is establishing theories and toolboxes in the following categories to help reduce carbon footprint and promote the sustainability of energy conversion systems.

  • Systematically Exploring New Electric Machines
  • Systematically Exploring New Power Electronics Circuits
  • High Performance Control Architecture for Electric Machines and Power Electronics

Why Systematic Exploration? (Using Electric Machines as an Example)

yet we still have a large uncharted performance space (PMVM has an impressive shear stress capability, but its CPSR is poor; other EMs with good CPSR do not have shear stress capability comparable to PMVM’s)
EM invention has been sporadic

Previous Research

Dr. Ge’s Ph.D. work focused on the design and modeling of dielectric-liquid-filled electrostatic machines (ESMs), an emerging family of machines that feature low cost, lightweight, high efficiency, and environmental friendliness. Before this research, ESMs’ 4 to 5 orders of mismatching on torque density with permanent magnet machines (PMs) had limited their applications to the small-size, low-power area such as microelectromechanical systems (MEMS), where magnetic machines are not feasible. This research managed to reduce the torque density gap between ESMs and PMs significantly while still maintaining ESM’s unique strengths via a multiplicative gain design approach. At the same time, a full design toolbox for the design and optimization of ESMs was created.

Dr. Ge had been conducting independent research during my spare time while continuing working on electrostatic machines at C-Motive. One work concerns the torque production capability of electric machines in view of the increasing demand from critical applications like electric vehicles, electric aircraft, and industrial robots. Another work extends the well-known winding function theory, which is generally considered a teaching tool bridging AC drive controls and machines, to incorporate nonlinear effects in electric machines. These works are at the preliminary stage but resulted in two transaction papers in top journals in 2021.

Previous Research Topic #1: High Torque Density Macro-Scale Electrostatic Rotating Machines

1st Gen: Dowel Pin Design, Radial Flux, Single Phase, 2~3 orders Improvement Over Prior Researchers
2nd Gen: 3D Printed Design, Radial Flux, Single Phase, 2~3x Improvement Over the 1st Gen

3rd Gen: PCB Plate Design, Axial Flux, Three Phase with Field Excitation, ~5x Improvement Over the 2nd Gen

Previous Research Topic #2: Design Toolbox for Electrostatic Machines

An Analytical Computational Program Solving Electrostatic Field in A Multi-Potential-Multi-Material Structure, 1% Relative Error to FEA, 1 sec Solving Time vs 9 hrs with FEA
An Asymptotical Torque Evaluation Method for Multi-Phase Electrostatic Machines, which Lends Itself to Design Considerations and Scalability Analysis
A Generalized dq-Axis Model (including Leakage Current) for the Drive Design and Control of Multi-Phase Electrostatic Machines
A Conformal Mapping Based Design Routine for Single Phase Electrostatic Machines

Previous Research Topic #3: High Performance Computing in the Design of Electric Machines

Conformal Mapping (Schwarz-Christoffel Transformation) with Nvidia GPU Acceleration, 19 msec per mapping with GTX480 vs 1.7 sec with i5-3470
Solving Laplace Equation using Finite Difference Method in a High Throughput Computing Environment (Fortran on HTCondor), ~16,600x Time Reduction

Previous Research Topic #4: Torque Production Capability of Surface Permanent Magnet Machines

Upper Bound of the Average Shear Stress in SPM Machines Assuming PMs have wide recoil capability and Electric Steel can Fully Use PMs’ Remanent Flux

Upper Bound of the Average Shear Stress in SPM Machines with Most Advanced PMs and Electric Steel Nowadays

Previous Research Topic #5: Extending Winding Function Theory to Incorporate Nonlinear Magnetic Effect