Recently, more and more power conversion applications, such as PV micro-inverters, battery storage systems, on-board EV chargers, etc., require isolated DC/AC power converters. The markets for these applications are rapidly growing. The conventional two-stage topology solutions have simple control, higher efficiency, and lower cost. However, they have low efficiency, high cost, low density, and complicated control.
This invention is proposed to combine both the benefits of the two-stage solutions and the single-stage solutions to significantly improve the performance and reduce the cost. In addition, the modular extended version of this topology solution dramatically reduces the cost for the systems containing multiple DC sources.
Researchers at The University of Texas at Austin propose a topology solution which combines the pulse width modulator (PWM) converter and the resonant converter. The cost of this solution is as low as the state-of-the-art single-stage solution. However, the efficiency can be even higher than the single-stage solution. Due to the simple and reliable zero voltage switching (ZVS) control and synchronous rectification (SR) control, the control and sensing complexity is even lower than the state-of-the-art two-stage solution. Thus, the frequency can be up to MHz level, which dramatically improves the power density.
The bidirectional power flow capability makes this solution suitable for many bidirectional power conversion systems. In addition, the modular extended version of this solution which uses a novel parallel structure significantly reduces the cost for the systems containing multiple DC sources. A few of the features include:
Figure 1. Proposed isolated DC/AC topology solution.
Figure 2. Topology with minimized switch count for the proposed solution with unfolding bridge.
Figure 3. Topology with minimized switch count for the proposed solution with AC switches.