E-Mobility Engineering 014 l InoBat Auto dossier l In Conversation: Brandon Fisher l Battery monitoring focus l Supercapacitor applications insight l Green-G ecarry digest l Lithium-sulphur batteries insight l Cell-to-pack batteries focus

Design unveiled for 800V inverter Components keep their cool in 3D Texas Instruments has developed a reference design for an 800 V, 11 kW three-level, three-phase inverter using gallium nitride (writes Nick Flaherty). The inverter uses a 6.6 kW active neutral-point clamped (ANPC) inverter design with a 600 V LMG3422R030 GaN FET. This enables a switching frequency of 100 kHz to reduce the size of the magnetics and increase the power density to 2.57 kW/litre. Its peak efficiency is 98.5%. Multi-level topologies enable the use of lower voltage switching devices, but come with limitations such as the need for more devices, resulting in lower reliability, the need to drive more switches and the need to avoid over-voltage, even during abnormal operation. The design shows how to address all 18 power devices in the power A feasibility study has examined the use of over-moulding to create 3D electronic components with high thermal conductivity (writes Nick Flaherty). The project, at Sobaplast in Germany, used the Keratherm MT 103 and MT 320 injection moulding materials from Kerafol on circuit board samples at temperatures that did not compromise the components on the board but still provided a high level of performance. This achieved electronic parts fully covered with thermally conductive but electrically isolating properties. The thermal conductivity results from filling the polymer with ceramic fillers such as AL 2 O 3 . This is a new approach that allows the circuit board and cooling plate to be connected stage with the limited number of PWM outputs available from a common C2000 microcontroller, as well as how to implement the hardware-based interlocking protection needed to avoid device over-voltage without the use of additional components. Another requirement that is becoming more prevalent for inverter power stages is the need for bidirectional power transfer. The ANPC’s power stage is inherently capable of bidirectional operation – only software is required for it to operate as or inverter or power factor controller. The modular design allows for easy replacement of power switching devices to enable easy comparisons between them. It consists of a motherboard with the filter, sensing electronics, bias power, switching relays and cooling fans, a TMDSCNCD280049C control in 3D. That means they can ensure higher levels of thermal management and simultaneous protection against environmental influences. card to support the DSP and six power cards switching at 100 kHz containing GaN power switching devices and isolated bias power supplies. Three power cards switching at 100 and 120 Hz contain silicon power switching devices, gate drivers and isolated bias power supplies. Although the board can accept 12 V bias power from an external power supply, it has provision for adding an auxiliary power supply that can run from the high- voltage DC bus. The melt flow index (MFI) of the materials is a key consideration for filling the mould without creating air bubbles, also called inclusions. MT 320 has an MFI of 10-20 g/10 minutes at 170 C, while MT 103 has an MFI of 4-10 g/10 minutes at the same temperature. Inclusions in the moulding would compromise the thermal performance, creating hotspots. Visible streaks on the surface of the samples are not critical, and are typical for highly filled plastics such as parts with a metallic pigment for household appliances and toys, said Kerafol. The low processing temperatures of the materials, of 150 to 180 C, are key to avoiding stress on circuit board components. The study examined the effective use of the materials at 150 ±20 C up to 180 ±20 C. INVERTERS THERMAL MANAGEMENT TheGrid Reference design for the GaN inverter Thermally conductive over-moulding creates 3D components 12 Summer 2022 | E-Mobility Engineering