Vehicle power module assembly with cooling

A vehicle power system may include a power module assembly having a plurality of alternating heatsinks and phase legs arranged in a deck. Each of the phase legs includes a semiconductor switch in contact with a dielectric layer. The dielectric layer is sandwiched between the switch and one of the heatsinks such that heat generated by the switch is transferred to the heatsink via the dielectric. At least one of the heatsinks may define a coolant channel. The coolant channel may be U-shaped. The coolant channel may have inlet and outlet regions. The inlet region may be opposite the outlet region. The coolant channel may have a divider to segregate ingress and egress coolant paths. The coolant channel may have obstructions to form a tortuous path. The obstructions may be wavy fins.