TIDUF63 December 2023
Energy sustainability and security are accelerating the demands for renewable energy as solar and energy storage systems. In residential use cases, micro inverters present a good trade-off in terms of costs and efficiency together with a simple end-user installation. Conversely, the energy storage system becomes a challenge in existing micro inverters due to the lack of a bidirectional converter in this end-equipment.
This reference design is intended to show a possible implementation of the 4-channel micro inverter with fully bidirectional power flow to combine PV input functionality with a 48-V BESS.
The design contains three main stages:
Each stage is based on GaN technology to achieve high power density and efficiency.
The reference design is made with two boards split by functions.
The first board is called DC/DC board containing four input DC/DC converters and one isolated CLLLC converter. All the conversion stages in the board are based on top-cooled GaN devices from TI and are placed on the bottom side of the board. This enables dissipation of the power losses into the heat sink.
The second board is called DC/AC board and contains DC link electrolytic capacitors, a totem-pole DC/AC converter, pre-charging circuit and EMI filter. The high-frequency branch of the totem-pole DC/AC is based on top-cooled GaN devices from TI.
Both the boards are mounted above an aluminum heat sink which is connected by means of thermal interface materials to the GaN FETs. The heat sink in the design is supposed to work in static cooling condition and the size is 15 mm × 250 mm × 250 mm. Overall system dimension is 40 mm × 250 mm × 250 mm, thus leading to a volume of 1.6 liter. The calculated power density is equal to 1 kW/liter.