FLEXIBLE POWER CONVERSION Multiport power converters: All-in-one solution

Related Vendors

SPACE SE & Co. KG

Caltest Instruments GmbH

MERSEN France SB

Modern power systems don’t have a single source or load. The need for efficiency drives a system to run multiple power conversion stages in parallel. A multiport converter (MPC) enters the picture, replacing modular power conversion cells. Simply put, multiport converters can replace cascaded converters by integrating more than two distinct energy sources and loads into a single aggregated controllable hub. In renewable-backed grids, multiport converters can result in efficient energy management, grid stability, and cost savings.

In distributed networks (DNs), multiple conversion stages make the entire system bulky and complex. Multiport converters replace power conversion stages with a single stage. These converters can have N input and M output ports. Based on the design, either a DC bus or a mult-winding high-frequency transformer can serve as the connecting link between all the ports.

Each port can either be unidirectional or bidirectional. Some research suggests that multiport converters might also integrate a single storage unit for the entire power system. Multiport converters can perform all the functions of a cascaded converter. Common MPC functions are DC-to-DC or DC-to-AC-to-DC power conversion. Buck and boost DC-to-DC converters are commonly used in MPC.

All DC-AC conversion and vice versa occur at the same switching frequency. The phase shift occurs between different ports. That’s how multiport converters can enable control over the direction and magnitude of power flow. A controller can control power flow using phase-shift modulation, pulse-width modulation (PWM), and predictive control strategies.

Multiport converters are of three types: isolated, non-isolated, and partially-isolated. Just as the name suggests, non-isolated multiport converters don’t offer electrical isolation. All the ports are connected across a common ground. DC-to-DC buck-boost multiport converters follow a non-isolated construction. The efficiency and power density of such converters are high.

Partially-isolated multiport power converters can isolate some power conversion stages (not all). Isolation exists between the source and load ports. All sources can be connected on a single bus. Partially isolated multiport power converters offer moderate-to-high efficiency in photovoltaic applications.

Isolated multiport converters provide complete isolation between all conversion stages using a multi-winding high-frequency transformer. Wide bandgap semiconductors, SiC and GaN, are used in isolated multiport converters. A GaN-based triple active bridge (TAB) multiport converter shows an efficiency of 98.87% at 100 kHz switching.

BASIC KNOWLEDGE

Cycloconverters in power electronics

Potential applications of multiport converters

Multiport converters are applicable in power electronics, industrial power management, electric vehicle charging, data centres, microgrids, and high-voltage applications.

EV charging: Multiport converters can help EV charging stations combine grid power, solar power, and battery storage. EV charging stations can perform vehicle-to-grid (V2G) and grid-to-vehicle (G2V) conversion. The extra power from the battery can be fed back to the grid.

Photovoltaic storage: A solar cell connected to a multiport converter can charge an EV battery (photovoltaic-to-vehicle - PV2V) or station battery for later use (photovoltaic-to-battery - PV2B). Multiport converters support maximum power point tracking (MPPT) in PV modules.

Microgrids: Multiport converters can support DC microgrids, grid islands, or nanogrids with multiple energy sources, including photovoltaics, battery energy storage systems (BESS), ultracapacitors for transients, and various others.

Data centres: The transition towards 400/800 HVDC at the rack calls for lower losses at each DC-to-DC converter stage. Multiport converters in data centres can connect series-stacked voltage domains to a shared stage using a multi-winding transformer.

expert SST TECHNOLOGY

Inside the Solid State Transformers

Benefits of multiport power converters

ScienceDirect shares three benefits of using an MPC over cascade converters: higher power density, fewer semiconductor switches, and a single point of control for bidirectional power flow.

• Multiport converters engineer bidirectional power flow.

• Multiport converters reduce the point of failure, component count, system weight, and power losses.

• Multiport converters are energy-efficient and support decarbonization initiatives.

Downside of multiport power converters

The only downside of multiport power converters is the lack of implementation and integration in real applications. Some manufacturers sell three-port DC-DC low-to-medium power converters for grid power, solar, and battery charging stations. Manufacturers and OEMs are yet to sell high-power standalone catalogue multiport converters that adhere to grid codes and meet all regulatory standards.

Researchers from Princeton University consider multiport converters a part of flexible, programmable, granular, and adaptive (FPGA) power electronics. They simulated a 100-port (multiport) power converter and built a 4-port (multiport) power converter to validate the simulation model. The main purpose of the developed multiport converter is based on programmable power flow.

References

• https://www.nature.com/articles/s41598-025-21893-8

• https://www.princeton.edu/~minjie/files/multiport_paper.pdf

• https://www.sciencedirect.com/science/article/pii/S2772671124001542

(ID:50859132)