PELS 1998 Prize Paper Awards

Thermal Analysis of High-Power Modules

C. Van Godbold is with the University of Michigan Dearborn, MI 48120 USA

V. Anand Sankaran is with the Vehicle Electronics Systems Department, Ford Research Laboratory, Dearborn, MI 48120 USA

Jerry L. Hudgins is with the Electrical and Computer Engineering Department, University of South Carolina, Columbia, SC 29208 USA

Abstract: A highly descriptive method for displaying heat flow in power mod-ules is presented. Heat flow is studied for three different transistor-stack types: direct bond copper (DBC), thick-film printed substrate, and insulated metal sub-strate (IMS). DBC and thick film are thermally superior to IMS, but IMS shows potential. In addition, the effect of case-to-sink interface conductivity on heat flow is studied and shown to be of extreme importance in a proper thermal simulation.

A New Low-Cost Fully Fault-Protected PWM-VSI Inverter with True Phase-Current Information

Frede Blaabjerg is with Aalborg University, Institute of Energy Technology, Aalborg East 9220 Denmark.

John K. Pedersen is with Aalborg University, Institute of Energy Technology, Aalborg East 9220 Denmark.

Abstract: This paper proposes a new topology for a low-cost three-phase pulse width modulation (PWM) VSI inverter where a true phase current information exists with the use of only one current sensor in the dc link. The topology also has the benefits of full protection of the inverter such as short circuits in the de link, output phase faults, and output earth faults. Previously suggested methods have problems at low speed in detecting the phase current, but by the use of space vector modulation in a double-sided implementation, the PWM-pulses are adjusted so true information about the phase current exists even at very low speed. The dc link current is sampled twice during one switching period, and it is proposed to sample in the center of the PWM-pulses to obtain a real average phase current. The effects of blanking-time and overmodulation are also discussed. The strategy is imple-mented in a 16-b microcontroller, and the test results show the technique is useful in the whole speed range. It is concluded by the use of the proposed topology that only one current sensor will be necessary in the future for PWM-VS1 inverters. Authors:Frede Blaabjerg (S'86-M'91) and John K. Pedersen (M'91) are with Aalborg University, Institute of Energy Technology, Aalborg East 9220 Denmark.

Finite-Element Formulation of Field-Based Subcircuits for Modeling of Magnetic Components with Hysteresis

Jia-Tzer Hsu is with the Univer-sity of Florida, Gainesville, FL 32611-6200 USA

Khai D. T. Ngo is with the Univer-sity of Florida, Gainesville, FL 32611-6200 USA

Abstract: A finite-element formulation is described for the development of field-based subcircuits for the elements in a magnetic component. Rate-dependent hysteresis, geometry, frequency, and waveshape effects are captured in the modeling methodology. Coupled transient simulation of electromagnetic fields (inside the core) and circuit phenomena is demonstrated in a companion paper.