Congratulating CPES graduate - Arthur Ball

Arthur Ball completed his Ph.D. program in November 2008, and joined VPT, Inc. in Blacksburg, VA, in December 2008 as a Senior Design Engineer.  His dissertation, "Thermal and Electrical Considerations for the Design of Highly-Integrated Point-of-Load Converters," is available online to CPES Principal Plus, Principal and Associate members via password access.

Arthur earned his Ph.D. and Master’s degrees in electrical engineering from CPES  - Virginia Tech. For undergraduate studies, he double-majored in mechanical and electrical engineering at Bluefield State College, completing both in 2000.  Having knowledge of both mechanical and electrical concepts landed him his first job where he did suspension and chassis design of electric baggage tractors, as well as specifying electrical motors and drive systems for them.

This special situation evolved in graduate school where his research focused on the interrelationships between mechanical system issues and electrical circuit design.  Arthur's work involved making a buck Point-of-Load converter (POL) that steps down 5VDC to 1.2VDC, switching at 1.3MHz. The special features of this module are: inductor, devices, snubber capacitor and thermal management are all integrated together into one compact module. To achieve this, aluminum nitride direct bonded copper was chosen (AlN DBC) as the substrate material for its excellent thermal properties – 5x better thermal conductivity than PCB which allows for heat to distribute uniformly, thereby allowing maximum package utilization to reduce size.

As a result, high frequency operation with small duty cycles in a small package is possible without having to resort to a bulky and costly heat sink or cooling fan. The inductor layer is fabricated using low temperature co-fired ceramic (LTCC) and is combined with the active layer where the devices are actually embedded inside the ceramic. A control layer on top completes the module. Natural convection is sufficient for the POL to output full 20A in up to 55°C ambient. High efficiencies of up to 92% (at 24% duty cycle and 1.3MHz) reduce wasted energy. All of this is achieved with a very high power density of up to 500 W/in³, which includes all thermal management in one compact module that has the footprint of a quarter coin and is only 8mm thick.

Arthur's hobbies include raising many types of orchids, 2-channel high fidelity audio, vacuum tube amplifier restoration, coin collecting (foreign and American), insect collecting, horse riding,1:43 scale model cars and antique automobile restoration.

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