With 12 AC or 24 DC switches, how can the UPC be economical?
A. Since soft switching is used which allows for slow switches, and the switches see no more than the twice the input line-to-neutral voltage (a little more than the peak line-to-line voltage), converter power per switch is comparable to standard power converters. And costs of power semiconductors have fallen dramatically, leaving most of the cost of a conventional IEEE 519 compliant motor drive in the large input filters. Most importantly, due to the relatively high frequency current source of the UPC, I/O filtering requirements are minimal.
