A power conversion system and methods of power conversion and construction of such a system are disclosed, where the system includes at least two pairs of input and output bus bars, and two pairs of switching devices, with the switching devices of each respective pair coupled in parallel in between a respective pair of the bus bars. When one of the switching devices of each pair is closed, the bus bars of the respective pair of bus bars are short-circuited to one another, thus bypassing the other of the switching devices of each pair. The other of the switching devices of each pair is attached to at least one intermediate portion, which in turn is attached to a mass. Substantially all the heat generated by the other of the switching devices of each pair is communicated to the mass, which has a heat capacity capable of receiving that heat.