The present invention relates to an ester composition that is suitable for successful operation in a dielectric fluid at extreme low temperatures, such as below about minus 50 C., without compromising the dielectric properties of the composition. The invention also relates to methods of manufacturing the ester composition and a dielectric fluid composition containing it.

A vehicle is provided with a transmission and an inductor assembly that is mounted within a chamber of the transmission. The inductor assembly includes a coil, a core and an insulator having first and second portions that are oriented toward each other. Each portion includes a base, a support extending from the base, and a spool extending transversely from the support to engage the other portion. Each spool includes an external surface for supporting the coil and a cavity extending therethrough for receiving the core.

A power converter includes: a first metal member; a second metal member to be connected to the first metal member to form a space in which a coolant flows; and a heating electric component main body to be housed in a concave portion formed on the first metal member so as to project into interior of the space.

A dielectric fluid and coolant for electrical apparatuses such as transformers. In one embodiment, the fluid contains more than 25% biobased base oil, such as a biobased hydrocarbon oil, which has a molecular weight greater than 300 g/mol and less than 595 g/mol. The biobased base oil may optionally be blended with other oils, such as mineral oils and vegetable oils.

A system and method for uniform cooling of an electromagnetic coil are provided. The system includes an electromagnetic coil, a cooling structure, and a cooling fluid source. The cooling structure surrounds the entirety of the perimeter of the electromagnetic coil, and includes a first cooling channel and a second cooling channel arranged alternately about the electromagnetic coil. The cooling fluid source is configured to deliver a first cooling fluid to the first cooling channel and a second cooling fluid to the second cooling channel, such that the first cooling fluid and the second cooling fluid cool the electromagnetic coil.

A power electronic transformer, including at least one first voltage unit including first voltage power electronics building blocks, at least one second voltage unit including second voltage power electronics building blocks, the first voltage being lower than the second voltage, and a two-phase cooling unit including a two-phase cooling medium for cooling the at least one second voltage unit. The two-phase cooling unit allows for an improved overall system performance of the transformer regarding costs, effort for maintenance, risk of malfunction or failure, and weight and footprint of the construction.