Improvement and Analysis of 3-Phase DCLA with Unequally Divided Source Voltage for Actual Implementation

A diode-clamped linear amplifier (DCLA) has been proposed as a power converter that does not generate high-frequency EMI due to switching. The DCLA consists of series connected multi-stage power supplies, FETs, and diodes connecting them. Since only one of the FETs operates in linear region, the DCLA can convert power more efficiently than general linear amplifier circuits. In the previous studies, it was shown that a single-phase DCLA with unequally divided DC voltage power supplies (DCLA-UeDV) can improve efficiency compared to DCLA with equally divided DC voltage power supplies (DCLA-eDV). In addition, the efficiency of 3-phase DCAL can be increased by applying zero-sequence voltage control method confirmed by simulations. Among various zero-sequence voltage methods, the highest efficiency can be obtained with a 2-phase modulation method. In this paper, an 8-stage three-phase DCLA is implemented and it is experimentally confirmed that the efficiency can be improved by DCLA-UeDV compared to the DCLA-eDV. Next, the issues involved in actual implementation two-phase modulation method to an experimental circuit are summarized then solutions are proposed. As a result, higher efficiency can be experimentally obtained by using the two-phase modulation method in three-phase DCLA.