Fraunhofer IZM has developed a 500-kW inverter that matches in a quantity of 1 liter—500 kVA per liter—with peak effectivity exceeding 99%. The unit was constructed for Mitsubishi Heavy Industries and is designed for 800 V DC drives, delivering 500 A RMS per part with an efficient inductance of roughly 1 nanohenry and switching speeds of 65 V/ns.
The design reaches these numbers by 4 interacting approaches. The ability modules use a two-level half-bridge topology, one per part, every with twelve silicon carbide MOSFETs embedded immediately onto the PCB. Embedding the SiC switches eliminates part top and cuts parasitic inductance. An RC snubber between every module and the DC-link capacitor reduces oscillations and will increase switching velocity. The ensuing 1 nH efficient inductance permits the MOSFETs to change at their bodily restrict—quicker switching means decrease losses, decreasing cooling necessities.
The second strategy is the cooler: a flat, extruded aluminum warmth sink beneath the three modules with greater than 40 skinny, barely corrugated channels giving coolant a big floor space for warmth change. All the warmth sink is produced in a single extrusion step, minimizing each value and kind issue.
The third strategy is the busbar connection. “The contacts of the busbars had been shaped simply in order that we might laser-weld them immediately onto the circuit board,” stated Wiljan Vermeer of Fraunhofer IZM’s Energy Digital Techniques group. “Meaning we might eliminate screws that may not solely eat up beneficial area however enhance inductance as properly.” The 2 enter busbars are organized vertically and shut sufficient that their magnetic fields partially cancel, additional decreasing inductance.
The fourth strategy addresses the DC-link capacitors. Working with PolyCharge, the crew used NanoLam capacitors particularly configured for the applying and organized alongside the busbars, reaching 2 nH whole DC-link inductance at 300 microfarads of capacitance. NanoLam capacitors produce increased thermal losses than standard sorts; the crew used copper contacts for higher warmth dissipation and built-in the capacitor unit into the casing beneath the aluminum cooler, limiting working temperature to 130 °C towards a 150 °C most.
Fraunhofer says the ensuing unit outperforms widespread inverter alternate options by 5 occasions on energy density and beats present prime methods by 2.5×. Vermeer will current the inverter at PCIM Europe in Nuremberg, June 9–11.
Supply: Fraunhofer IZM
