UW researchers a novel cooling method for radial flux machines using a heat exchanger, which is placed inside the radial cooling ducts, encircling stator slots, and featuring coolant flow in the circumferential direction. The heat exchanger is composed of two parts: base and cover. The heat is evacuated with the coolant pumped through the inlet. The heat exchanger encircles the stator slots and coils, and there is direct contact between stator coils and heat exchangers enhancing the thermal performance. The heat exchanger has the same profile with a stator lamination. Thus, it has the same number of slots (or teeth) as the number of stator slots (or teeth). It is located at the middle of the stator package, and it is sandwiched between two stator sub-stacks. Coolant flows through the channels using similar pumps that are currently used in electric machines. Since there is direct contact between the heat exchanger and the stator coils and core, effective cooling of the stator coils and core can be achieved without degradation in the slot fill factor. Other methods such as heat pipes and some cooling jackets require cut outs in the stator laminations. The inventors have different embodiments, with multiple heat exchangers with varying the offsets of the inlet/outlet configuration and embodiments with the cooling fluid flowing in various directions.