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Investigation of Emerging Power Electronics Technologies in EV Applications

Description
Due to the reduced fuel usage and greenhouse emission advantage, the sales of electric vehicles (EV) have risen dramatically in recent years. Generally speaking, the EVs are pursuing higher power and lighter weight, which requires higher power density for all the power electronics converters in the EVs. To design higher…

Due to the reduced fuel usage and greenhouse emission advantage, the sales of electric vehicles (EV) have risen dramatically in recent years. Generally speaking, the EVs are pursuing higher power and lighter weight, which requires higher power density for all the power electronics converters in the EVs. To design higher density power converters, three key emerging power electronics technologies are investigated in this study. First, the PCB-based magnetics are beneficial for improving the power density due to their low-profile structure. However, the high winding capacitance is considered one of the significant drawbacks of PCB-based magnetics. In this study, a novel winding structure is proposed to cut down the winding capacitance by 75% with little compromise of the winding loss. Second, the synchronous rectifiers (SR) are usually utilized to improve the system efficiency and power density compared with the conventional diode bridge rectifiers for the AC/DC stage in the power converters. The SRs are desired to be turned off at current zero-crossing to generate a minimal loss. However, the precise current zero-crossing detection is very challenging in high-frequency and high-power-density converters. In this study, a high-dv/dt-immune and parameter-adaptive SR driving scheme is proposed to guarantee the zero-current switching (ZCS) of SRs in various operating conditions and improve the system efficiency by 1.23%. Finally, Gallium Nitride (GaN) semiconductors are considered less lossy than Silicon (Si) semiconductors. However, the voltage rating of the commercial GaN HEMTs is limited to 600/650 V due to the lateral structure, which is not suitable for the 800 V or higher dc-link voltage EV systems. Stacking the low-voltage rating devices is a straightforward approach to sustain higher dc-link voltage. However, unbalanced voltage sharing can occur, which can damage the low-voltage rating devices in the stack. In this study, a novel active current source gate driver is proposed to suppress the over-voltage of the stacking devices below 10% for all operating conditions without sacrificing switching speed or switching energy. The above emerging power electronics technologies are investigated thoroughly in the dissertation. The proposed approaches are practical for improving power converters’ density in future EV applications.
ContributorsZhang, Zhengda (Author) / Lei, Qin Q.L. (Thesis advisor) / Ayyanar, Raja R.A. (Committee member) / Yu, Hongbin H.Y. (Committee member) / Pal, Anamitra A.P. (Committee member) / Ranjram, Mike M.R. (Committee member) / Arizona State University (Publisher)
Created2021

Arizona State University: Electric Vehicle Program

Description

One solution to the problems of poor air quality in Phoenix, Arizona and global climate change is to alter the way the population uses transportation. In the US, around one-fifth of all carbon dioxide (CO2) emissions are due to cars and trucks used for transportation and the increasing level of…

One solution to the problems of poor air quality in Phoenix, Arizona and global climate change is to alter the way the population uses transportation. In the US, around one-fifth of all carbon dioxide (CO2) emissions are due to cars and trucks used for transportation and the increasing level of CO2 emissions is exacerbating our impact on the climate and is causing a shift in climate. By switching from combustion engine vehicles to public transportation, electric vehicles, or going entirely vehicle-less, the amount of CO2 being released into the atmosphere every day will be decreased and overall air quality within cities will improve. If public transportation, riding a bicycle or walking is not an option, electric vehicles (EVs) are ideal as a lower-carbon emitting option over traditional combustion engines when they are recharged using renewable energy sources, like solar.

To encourage the adoption of EVs, this project pushed to overcome a few of the traditional barriers to adoption – initial cost, charging station infrastructure, and education about EVs. First, charging infrastructure was installed on all four ASU campuses. Then, to discover the biggest barriers to EV adoption, a literature review was conducted to develop a general understanding of barriers which guided the creation of survey questions. This survey was distributed to all staff and faculty at ASU (over 9,500 individuals) and received over 1,400 responses. To begin building the EV program at ASU, other universities with EV programs were interviewed to learn best practices and to understand what is most effective in encouraging EV adoption on campus. The responses determined that ASU needs to:

1. Install more charging stations on campus.
2. Offer premium parking for EV/hybrid users or a discounted parking pass or free charging.
3. Add charging stations to ASU interactive map.
4. Develop an incentive program with EV dealerships.

The project built partnerships with EV dealerships to lower the initial costs associated with buying and leasing EVs. Finally, to increase awareness of EVs, the dealership partners brought EVs to campus for a demonstration day paired with Earth Day. The ASU EV program will reduce barriers to EV adoption to help reduce CO2 emissions related to transportation at the ASU campuses and improve city air quality.
ContributorsKutter, Kayla (Author, Project director)
Created2019-05-15