This paper deals with control and design of quasi-direct converters, i
.e., ac/ac converters including a forced-commutated rectifier, an inve
rter, and a small filter in the dc link. Converter performance can be
optimized by means of a predictive digital control strategy, which ens
ures instantaneous input-output power balance, fast response, and high
power factor. After a discussion of the control strategy, the paper g
ives design criteria of both power and control sections. Experimental
results of a 2.5-kVA prototype are reported.