Abstract—This paper presents a two-phase cooling method
using the R134a refrigerant to dissipate the heat energy (loss) generated
by power electronics (PEs), such as those associated with
rectifiers, converters, and inverters for a specific application in
hybrid-electric vehicles. The cooling method involves submerging
PE devices in an R134a bath, which limits the junction temperature
of PE devices while conserving weight and volume of the heat
sink without sacrificing equipment reliability. First, experimental
tests that included an extended soak for more than 850 days
were performed on a submerged insulated gate bipolar transistor
(IGBT) and gate-controller card to study dielectric characteristics,
deterioration effects, and heat-flux capabilities of R134a. Results
from these tests illustrate that R134a has high dielectric characteristics
and no deterioration of electrical components. Second,
experimental tests that included a simultaneous operation with a
mock automotive air-conditioner (A/C) system were performed on
the same IGBT and gate-controller card. Data extrapolation from
these tests determined that a typical automotive A/C system has
more than sufficient cooling capacity to cool a typical 30-kW traction
inverter. Last, a discussion and simulation of active cooling of
the IGBT junction layer with the R134a refrigerant is given. This
technique will drastically increase the forward current ratings and
reliability of the PE device.