Power Transistorized Uninterruptible Power Supply

Rotary-type uninterruptible power supply (UPS) units, which were in extensive use in the past, have been superseded by static-type units using thyristor inverters. Application of power transistors in an UPS unit has been under study in an effort to attain higher performance and compactness. The output capacity of a transistorized UPS unit has been increased from 20 to 100 kVA by the development of a new power transistor, a new protective method, and a new control method. A reduction of outline dimensions has been achieved (the volume reduction rate claimed is 1-3.5), and an improvement of conversion efficiency (approximately five percent), etc.