Hitachi Automotive Systems has begun to supply Daimler with compact, high-output inverters and DC/DC converters for use in the Mercedes S500 and S550 plug-in hybrids, which recently went on sale in Germany.

Hitachi developed a third-generation inverter that is 40% smaller and offers higher output than the previous version, and a high-output DC/DC converter with a maximum efficiency of 94%.

Direct double-sided water-cooled power module

To reduce the size and increase the power output of an inverter, it is essential to boost the heat dissipation performance of the power module. In its second-generation product, Hitachi improved heat dissipation by developing a water-cooled power module. The third generation further improved the ability to eliminate heat with a double-sided cooling structure that directly cools both major semiconductor surfaces of the power module.

High-output third-generation inverter

The new power module has achieved a 35% improvement in heat dissipation performance, while also reducing size and increasing power output by around 40%.

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The DC/DC converter features a proprietary active clamp circuit, in combination with a high-heat-emitting transformer and a low-loss, high-heat-dissipation choke coil structure.

Source: Hitachi via Green Car Congress