Development of the Intelligent Power Unit for the V6 Hybrid Midsize Sedan

The Intelligent Power Unit (IPU) of the Integrated Motor Assist (IMA) system was developed with the dual objectives of increased output and reduced size. To realize miniaturization and to reduce energy losses, fine patterning of IGBT chips in the inverter was conducted, transfer mold power modules were used, and film capacitors were integrated in the unit. Parts integration by digital control was performed in the 12V DC-DC converter. The internal resistance was reduced and the output increased of the IMA battery by changing the construction of the current collector and increasing the length of the electrodes. The battery box was made of a new design enabling easy assembly. The cooling system construction of the box was modified, and the pitch between the modules was reduced, enabling the battery box to be made more compact.

Thanks to the technological developments mentioned above, an increase in output of 20% and a reduction in size of 20% were achieved simultaneously for the new IPU, ensuring adequate running performance and cabin space befitting mid-size four-door sedans.