Efficient Gallium Nitride-Based AC-DC Power Conversion Circuits for Information Technology, Electric Transportation and Industrial Applications

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Consumer and industrial applications, including computers, electric vehicles, information technology servers and industrial battery powered devices make extensive use of electrical energy. The electrical energy must be converted from the alternating current (AC) utility voltage (e.g. 120 V) to a direct current (DC) voltage (e.g. 48 V and 400 V) to power these applications. High switching frequency (e.g. tens to hundreds of kilohertz) AC-DC rectifier circuits are used for this voltage conversion. The size of many of the converter components reduces proportionately to the switching frequency, so increased switching frequencies are desired. The problem is that losses in the circuits tend to increases proportionally to switching frequency, making the AC-DC power conversion circuits, inherently less efficient at higher switching frequencies. Therefore, new technologies are required to enable higher switching frequencies while reducing losses. The objectives of the proposed research program include invention, analysis and experimental evaluation of novel technologies for consumer and industrial kilowatt power AC-to-DC rectifiers using gallium nitride switches at megahertz switching frequencies in the following areas: i) Non-isolated bridgeless power factor correction circuits to reduce switching and conduction losses. ii) Isolated DC-DC power converter circuits to improve the efficiency of second-stage isolated DC-DC converters. iii) Isolated single-stage power factor correction circuits to reduce switching and conduction losses. The long-term objective of this research program is to develop novel technologies to increase the power conversion efficiency for kilowatt power level AC-DC rectifiers. The technologies developed in the proposed program will be used in a wide range of future generation consumer and industrial products, ranging from information technology server power supplies to industrial and electric vehicle battery chargers. It is expected that the technologies to be proposed in this research program will enable power conversion efficiency improvements of at least three percentage points, resulting in a reduction in the energy generation required to provide power to these products and a corresponding reduction in greenhouse gas emissions.