Powering the Future: The Role of Multi-Active Bridge Converters in Modern Electric Systems
In today’s rapidly changing world, electricity isn’t simply coming from a few centralised power plants. We’re seeing a major shift in the way energy is generated, stored, and used. Modern electric systems now include a diverse mix of DC (Direct Current) sources, each playing an essential role in the energy ecosystem. For example, solar panels generate clean energy directly from sunlight, batteries store power for when it’s needed, and fuel cells provide reliable energy even in remote locations. On top of that, electric vehicles (EVs) and their charging stations, the onboard power systems of ships, and even electric aircraft are now key players in this dynamic environment. Each of these systems serves a unique purpose, yet they all need a way to connect, share energy, and work seamlessly together. Enter the multi-active bridge (MAB) DC/DC converter, a powerful tool for making these complex energy networks possible.
An MAB DC/DC converter is a multi-port power converter that makes it much easier for these different DC sources and storage systems to interact. In essence, it acts like a bridge that transfers energy between various parts of a system. Unlike single converters, an MAB converter can handle multiple inputs and outputs at the same time, which makes it especially useful in complex power setups like renewable energy grids and electric vehicles.
So why are MAB converters so valuable in modern electric systems? For one, they enable flexible power flow, meaning energy can be directed wherever it’s needed across the system. This capability is essential for balancing energy between sources like solar panels, batteries, and EV chargers. Another major advantage is efficiency. By reducing the number of conversion stages (steps where energy can be lost), MAB converters ensure that more power reaches its final destination, be it an EV battery or an aeroplane’s onboard system. They also save space, as a single MAB converter can replace multiple single-purpose converters. This is particularly valuable in applications with limited space, such as EVs and aircraft. Additionally, MAB converters offer precise control over energy flow, which can improve performance and reliability across the entire system, a critical benefit for applications like the onboard power systems in electric aircraft.
Yet, achieving these advantages comes with challenges. One of the biggest is managing “cross-coupling” between the multiple power paths in an MAB converter. Cross-coupling means that any change in one of the converter’s ports—like adjusting the power output or input—can cause unwanted effects on the other ports, creating disturbances across the system. Addressing this issue requires careful design, and many researchers, including myself, are working to find solutions. I’m currently exploring ways to reduce these control complexities at the hardware level by modifying the basic structure of the MAB converter. My approaches include using resonant circuits and adjusting AC inductances. I’m testing these ideas on SiC-based converters, specifically a 4 kW, 4-port model and a 10 kW, 6-port model, shown below.
