Infineon advances solutions to support three-phase hybrid inverters

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Infineon has recently introduced the second generation of its silicon carbide (SiC) technology, which the company says promises to further elevate the efficiency of hybrid inverters and set new benchmarks in figures of merit (FoMs). The company’s three-phase hybrid inverter solutions optimize the use of solar power, particularly for power generation needs up to 30 kW.

“Of course, a photovoltaic inverter system consists of many building blocks, such as control, connectivity, and sensing technologies alongside the different power conversion stages,” Dominik Bilo, Infineon’s Executive Vice President and CSO of its Industrial & Infrastructure segment, says. “Infineon currently offers suitable components for all of these areas, which are combined in a unique system approach.”

Photovoltaic (PV) systems are one of the linchpins of the energy transition, and inverters link them to the public grid. In its simplest version, an inverter is comprised of a DC-DC boost converter to stabilize the PV arrays’ voltage and a DC-AC inverter for the grid connection. Infineon notes that hybrid inverters with up to 30 kW of output power help users achieve solar self-consumption using 30% fewer materials and up to 40% less space while reducing the complexity needed to build PV systems.

These devices not only convert DC to AC like string inverters, but they can also supply power in its DC form directly to an energy storage system (ESS) like a battery, thus avoiding redundant power conversions and trimming energy losses and material costs. A key focus lies in minimizing a system’s bill of materials (BoM) by incorporating a high-efficiency DC-DC converter stage for battery charging and discharging. Infineon has published a white paper detailing the effects of its semiconductor solutions for string and hybrid inverters.

Choice is pivotal when considering topology and chip technology within a DC-AC inverter block. When comparing traditional silicon technologies, two-level topologies experience measurable heavy efficiency losses at switching frequencies above 8 kHz. In contrast, the three-level NPC-1 and NPC-2 topologies stand out with regard to efficiency and low power losses (Figure 1). The three-level NPC-1 topology supports operations above 24 kHz, while the three-level NPC-2 is optimal for frequencies below this threshold.

Figure 1: Topology and chip technology choices for the DC-AC stage to build an efficient and compact hybrid inverter.

Image: Infineon

When comparing topologies using hybrid and SiC chip technology, Infineon notes that the use of a three-level NPC-2 topology with hybrid and SiC solutions enables the designer to further increase the switching speed to two times faster than the silicon solution – however, the losses remain the same (Figure 1 and Table 1). In general, the increased cost of the power semiconductor will be compensated for through the reduction in filter inductance size, weight, and cost made possible by the increased switching frequency operation. Furthermore, a lower operational temperature can reduce the size of the housing and enables fanless designs.

Such features make a big difference in residential and commercial installations, where quieter and smaller systems are required. Infineon emphasizes that the ultimate reduction in the number of materials needed allows manufacturers to build lighter and more efficient hybrid inverters.

Table 1: Comparison of topology and chip technology for DC-AC inverters.

Image: Infineon

 

 

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