Technical Field
The embodiments herein generally relate to power converters, and more particularly to power converters using Dual Active Bridge (DAB) topologies.
Description of the Related Art
DC to DC converters convert power at one DC input voltage to DC power at another output voltage. The input DC voltage could be unregulated while the DC output voltage could be regulated to a fixed value by the converter.
The continuous decline of photovoltaic (PV) module prices compounded with attractive feed-in tariffs in a variety of jurisdictions is leading to the rapid deployment of PV installations throughout the world. The intermittent nature of PV power, and thus the need for energy storage and/or load shedding, is a major challenge in small-scale PV based grids, even if power-quality and up-time requirements are reduced compared to conventional grids. Low-power DC-DC Micro-Converters (MIC) and AC-DC Micro-Inverters (MIV) provide high-granularity distributed Maximum Power Point Tracking (MPPT) at the module or sub-string level. This generally leads to increased robustness to clouds, dirt, and aging effects as well as irradiance and temperature gradients.
Existing MIV architectures satisfy the need for low capital cost and expandable AC generation, and there is a compelling argument to extend this technology to include small-scale distributed storage. A conventional MW based AC power system is shown in FIG. 1A. The Central Energy Storage System (ESS) is typically based on a high power centralized bi-directional AC-DC converter connected to a battery bank or a flywheel. Integrated storage helps to buffer the frequent insolation fluctuations, while also providing back-up power and reactive power support if needed. The industry has developed a low power, single-stage multi-port converter for PV and battery technologies. Moreover, the industry has developed a 3 kW interconnection of a battery pack and a PV module through an isolated DC-DC converter topology. The general architecture of a two-stage MIV with an integrated ESS is shown in FIG. 1B. While two-stage MIVs usually have slightly lower efficiency than single-stage MIVs, the high-voltage DC link capacitance, Cbus, can be used for AC power decoupling in single-phase systems, eliminating the need for electrolytic capacitors that limit the system reliability.