University of Southern Denmark
Mærsk Møler Mc-Kinney Institute
Challenges
Objectives
• Modeling of power loss
o Switching loss
o Inductor loss: Core loss and copper loss
• Design/Develop two level PFC using SiC devices 10 kW – 20 kW;
• Design/Develop multilevel PFC using GaN devices 10 kW- 20 kW;
• Maximize the efficiency;
• Maximize the power density;
• Maximize the power quality in terms of quality of input current, power
• Using WBG power switches in:
o Three-phase two-level PFCs
o Three-phase three-level PFCs
• Paralleling of the power switches
factor;
• Soft-switching techniques
• Provide bidirectional power flow;
• EMI mitigation.
Key Methods
Introduction
(I) Hardware implementation of two-level PFC using SiC switches.
Why PFCs?
The drawbacks of the conventional rectifiers
• Poor power quality in terms of
o High total harmonic distortion (THD);
o Poor power factor (PF);
o Considerable voltage-ripple at load end.
• Large size of AC and DC filters and components.
Advantages of PFCs
(a) The current or voltage can be modulated, generating less harmonic contribution;
(b) Power factor can be controlled;
(c) They can be built as voltage source or current source rectifiers.
Definition
a PFC shapes the input current of the power supplies to maximize the real power
available from the main.
The main question
This PhD project is going to answer this question: what are the possible ways of
increasing the efficiency of the three-phase PFC?
Main Phases of the PhD project
(1) To design and implement a high efficient two-level PFC using SiC power
semiconductor in the power range of 10 kW- 20 kW
(2) To design and implement a high efficient three-level PFC using GaN power
semiconductors in the power range of 10 kW- 20 kW.
Three-phase Two-level PFC
• Study/Design of the magnetic devices (inductors).
• Study/Analyze of the both switching loss and conduction loss of
the SiC switches in hard switching method; due to lower onresistance of the SiC switches the conduction losses will be
reduced significantly. Also, good transient performance of these
switches, it can be expected to have lower switching loss in
comparison with Si switches.
• Study of the impact of changing switching frequency on the whole
system efficiency; it leads us to find an optimum switching
frequency which provides a good trade-off between switching loss
and inductor loss.
• Present a comparison between the previous PFC using Si switches
and the designed PFC using SiC.
• Propose a comprehensive model for losses in the two-level
converters.
• Feasibility study/analyze of applying soft-switching technique to
reduce the switching loss.
(II) Hardware implementation of a three-level PFC using GaN switches.
• Designing test bench of the desired three-level converter; the
switching frequency can be higher in this case in comparison with
the common two-level converters while the GaN devices can be
switched very fast.
• Study/Analyze of the both switching loss and conduction loss of
the GaN switches in hard switching method; due to lower onresistance of the GaN switches the conduction losses will be
reduced significantly. Moreover, due to good transient behavior of
these switches it is also expected to have lower switching losses.
• A comparison between the previous PFC using Si switches and the
designed three-level PFC.
Inductor current and voltage in PFCs
Three-phase Three-level PFC
References:
[1] Singh, Bhim; Singh, B.N.; Chandra, A.; Al-Haddad, K.; Pandey, A.; Kothari, D.P., "A review of three-phase improved power quality AC-DC converters," Industrial Electronics, IEEE Transactions on , vol.51, no.3,
pp.641-660, June 2004.
[2] Hengchun Mao; Lee, F.C.Y.; Boroyevich, D.; Hiti, S., "Review of high-performance three-phase power-factor correction circuits," Industrial Electronics, IEEE Transactions on, vol.44, no.4, pp.437-446, Aug 1997.
[3] Jovanovic, M.M.; Yungtaek Jang, "State-of-the-art, single-phase, active power-factor-correction techniques for high-power applications - an overview," Industrial Electronics, IEEE Transactions on, vol.52, no.3,
pp.701-708, June 2005.
[4] Mohan, Undeland, Robbins, 1989, "Power Electronics: Converters, Applications, and design," John Wiley.