A dynamic voltage restorer equipped with a high-frequency isolated dc-dc converter

This paper presents a dynamic voltage restorer (DVR) that is characterized by the use of a high-frequency unidirectional isolated dc-dc converter. A traditional DVR has a large and bulky series transformer even for low-voltage (200 or 400 V) applications because the transformer operates at the line frequency (50 or 60 Hz). The emergence of the state-of-the-art semiconductor devices and magnetic cores has driven power electronics engineers to develop compact high-frequency isolated dc-dc converters. This paper discusses control and performance of a DVR including a high-frequency isolated dc-dc converter intended for 200 or 400-V applications. The high-frequency (20 kHz) transformer in the dc-dc converter is much smaller, say one-hundredth, in volume than the line-frequency transformer. Moreover, connecting the shunt converter to the load side brings a significant reduction in energy-storage capacity to the DVR. Experimental results obtained from a 200-V 5-kW laboratory system confirm the viability and effectiveness of the system configuration.