Climate concerns and geopolitical instability are driving demand for energy self-consumption. Photovoltaic (PV) provides an accessible way to achieve such energy independence by making energy generation and consumption possible at home. However, traditional string or microinverters cannot address the need for energy storage. This is where hybrid inverters come in.
Hybrid inverters open up new doors for self-consumption, while reducing the amount of materials, space, and complexity needed to build PV systems. Not only are they designed to connect multiple PV panels and convert the generated DC current to AC, they can also supply DC currents directly to an Energy Storage System (ESS) like a battery. By integrating the ESS component, hybrid inverters eliminate unnecessary power conversions and thus, reduce losses.
Infineon offers a wide range of solutions for your 3-phase hybrid inverter – from power and sensing, to control and connectivity.
Several main topologies are used in the power stages of 3-phase hybrid inverters.
First, the DC-DC stage converts variable DC voltage into a fixed DC voltage while simultaneously ensuring maximum power is extracted from the PV panel through a MPPT (Maximum Power Point Tracking) technique. In general, simple boost topology is preferred in this stage.
Next, the DC-DC stage enables bi-directional energy transfer between the battery ESS and the DC bus. In general, for high-voltage batteries, non-isolated bi-directional DC-DC converters are preferred, and for low-voltage batteries, isolated bi-directional DC-DC converters are used.
Finally, the DC-AC stage converts DC power into grid-compatible AC power. Either 2-level or 3-level topology is preferred in this stage. In particular, 3-level NPC1/NPC2 topology is widely used for its higher efficiency. The 3-level NPC1 enables more than 20 kHz switching frequency operation, even for oversized PV panels. The 3-level NPC2 uses 600 V and 1200 V devices, which are the most suitable topology for less than 20 kHz switching frequency operation.
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