Feb 26, 2014 - vents traction motor drives from exceeding the low switching frequencies. (tens of kilohertz) due to excessive switching losses. This is important ...
By Pourya Shamsi, Matthew McDonough, and Babak Fahimi
Wide-Bandgap Semiconductor Technology Its impact on the electrification of the transportation industry.
semiconductor courtesy of wikimedia commons/eproms national semiconductor
HE EFFICIENCY OF ANY ELECTRIC VEHICLE (EV) is limited by the efficiency of its power electronic motor drive. Currently, EVs use conventional silicon (Si) insulated-gate bipolar transistor (IGBT) or Si metal–oxide–semiconductor field-effect transistor (MOSFET) technologies. Si technology prevents traction motor drives from exceeding the low switching frequencies (tens of kilohertz) due to excessive switching losses. This is important as the size of passive components (and thus cost) is inversely related to the switching frequency. Recent advancements in semiconductor technologies have brought the utilization of widebandgap semiconductor technologies for applications in electrified transportation within reach. Gallium nitride (GaN) and silicon carbide (SiC) technologies have lower switching losses and lower on-resistance than conventional Si devices. This will allow engineers to increase the switching frequency while simultaneously improving efficiency in motor drives. This makes
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Digital Object Identifier 10.1109/MELE.2013.2293931 Date of publication: 26 February 2014
IEEE Elec trific ation Magazine / d ec emb er 201 3
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higher-voltage GaN HEMT. However, the result of the cascode configuration demonstrates inferior characteristics both in efficiency and switching times as compared to GaN HEMT. Recently, the development of enhanced-mode GaN (e-GaN) FETs revolutionized applications of GaN technology in dc–dc power converters. These switches provide high performance while simply replacing conventional normally off Si switches. If these e-GaNs are scaled up in power, they will be attractive alternatives for traction motor drives.
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Drain Voltage 2.50 GS/s 4 50.0 V 40.0 ns 129.200 ns 10 k Points T
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Another additional cost that must be considered to migrate to wide- bandgap technologies in automotive motor drives is the cost associated Figure 1. The measured signals from a low-speed gate driver for SiC MOSFETs. with replacing the gate driver circuits. For commercially available SiC MOSwide-bandgap devices an attractive replacement for tracFETs, the recommended on-voltage is 20 V, which is higher tion motor drives. than that for the Si technology. Conventional gate driver auxiliary power supplies must be redesigned, and new gate Economics/Manufacturing drivers with higher voltage (and thus peak current) tolerCurrently, economic concerns are the main roadblock in ances must be used. Gate drivers that fit these requirethe integration of wide-bandgap technologies in automoments exist; however, they are more expensive than tive motor drives. SiC technology is not compatible with conventional Si gate drivers. conventional fabrication equipment in semiconductor e-GaN switches require 5 V for optimal operations of the production companies. Hence, to compensate for installswitch. To benefit from the fast switching times of this teching the new equipment, these switches carry a high price nology, fast gate drivers are required. Because of the fast tag. The production processes for epitaxial-ready GaN subswitching times of GaN switches (i.e.,
