The Army is committed to hybrid electric combat vehicles for deployment in the next century. The key consideration for such systems is to minimize system volume, since interior vehicle volume, particularly under armor, is at a premium. A variety of power converters are required. It is therefore beneficial to reduce converter volume as much as possible, yet maximize efficiency, versatility and maintain high power quality. In a prior study[1], the Army Research Laboratory (ARL) determined that compact converters are feasible. The most significant finding of the study was the substantial space savings obtainable if the passive components of the filter section commonly found in standard DC link converters were eliminated. This may be done with the matrix converter, an AC to AC converter. The technology is not new, but has not been utilized extensively in the past due to the complexity of control required to efficiency operate such converters. The ARL matrix converter project will take advantage of the inherent advantages of matrix converters, to improve Army vehicle systems. The matrix converter lends itself to other than AC to AC conversion. DC to AC and AC to DC are also feasible utilizing the same components, with a different control sequence[2]. This is extremely useful in Army systems, since one type of converter being capable of performing several functions reduces the logistic burden.
The ARL effort is examining the effect of various types of solid state switches, including MOS Controlled Thyristors (MCTs), MOS Turnoff Thyristors (MTOs) and the advanced switches being developed under the Power Electronic Building Block (PEBB) program. The operational characteristics of each type of switch, such as commutation and conduction losses, and their effect on thermal management and the implications on vehicle mounted cooling system requirements are also addressed. Power quality issues are also examined in detail.