Cooling IGBT Modules with VDF - Parker

Key Points: VDF Cooling Loop
• VDF system:
• Pressure and temperature are allowed to “float” relative to ambient conditions.
• System design target: System is designed for maximum power load at maximum
ambient conditions.
• No compression cycle: System cannot cool below heat exchanger medium
temperature. This is not refrigeration.
• Gravity fed:
• Pump must be located below liquid cold plates in the loop.
• Heat exchanger must be located above the liquid cold plates in the loop.
• Heat exchanger can be:
• Air-to-fluid (i.e., traditional tube-and-fin);
• Water-to-fluid (e.g., shell-and-tube for external chilled water or tower).
• System design engineer may set the refrigerant saturation temperature by adjusting
system operating pressure:
• Adds additional degree of freedom for system design;
• Higher pressure will increase saturation temperature, enabling a higher junction
temperature and smaller condenser and/or lower airflow.
• Refrigerant or other dielectric vaporizable fluid will tolerate greater temperature
extremes for outdoor applications.
• “Refrigerant agnostic”: Alternative refrigerants and dielectric fluids may be selected,
with some changes required in system component design.
7 Levett, Howes, Saums – Cooling of IGBT Modules with Vaporizable Dielectric Fluid • IMAPS France ATW Thermal 2008 • La Rochelle, France