Hitachi, Ltd.

Mami Kunihiro

Katsumi Ishikawa

Tsutomu Kominami

Kazutoshi Ogawa

Hideki Ayano

Sunao Funakoshi

Temperature rise in semiconductor switching element that is part of a power conversion device is estimated to assess the degradation and remaining lifetime of the switching element. This is accomplished with a heat generation amount calculation unit in a calculation processor, where current command values Id* and Iq* and voltage command values vu*, vv* and vw* are used to calculate a chip loss. Current values iu*, iv* and iw* of all output phases are estimated from the current command values. The ON/OFF loss of the chip is represented by a function of an estimated value for a current flowing in each output phase, and the loss can be derived by integration with a PWM carrier frequency f. With respect to a conduction loss, a conduction time is integrated with the estimated current value and a saturation voltage, which is a function of the estimated current value.

Power conversion device and temperature rise calculation method thereof

A power converter including: a plurality of semiconductor devices forming a power conversion circuit; a base section to which the plurality of semiconductor devices are attached; and radiating fins dissipating heat generated from the semiconductor devices into outside air, in the power converter in which the direction of the flow of a refrigerant flowing into the radiating fins changes depending on the operation status of the power conversion circuit, the shape of each radiating fin changes in such a way that the cross-sectional area of a channel of the refrigerant on the outflow side becomes smaller than the cross-sectional area of the channel of the refrigerant on the inflow side in the radiating fins depending on the direction of the flow of the refrigerant.

Power converter

The present invention provides a power converter which, while ensuring safety, implements control for the flow of a constant current in a specified switching element, more accurately determines the lifetime of a switching element, and reduces the number of temperature detectors. The power converter is provided with a mechanism which causes a brake device to operate or which confirms that a brake mechanism is operating. The power converter supplies current to the d-axis and the q-axis of a rotational coordinate system, within the range of the braking torque of the brake mechanism, and passes the desired current to the desired element. Furthermore, temperature detectors are attached only in chips in sections where a crack readily develops in the upper solder layer or peeling is readily generated in the wire bonding, and in chips where a crack readily develops in the lower solder layer.

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Hitachi, Japan

Mami Kunihiro