Wechselrichter für ein elektrisches Betriebsmittel

摘要

An inverter apparatus for electric rolling stock employs a 3-level inverter including four semiconductor switch modules (SM1...SM4) connected in series to DC power source terminals P and N, the node of the first and second semiconductor switch modules and the node of the third and fourth semiconductor switch modules being connected to the neutral point of the DC power source through the intermediation of clamp diodes, the node of the second and third semiconductor switch modules being connected to an AC output terminal. The loss of the first and fourth semiconductor switch modules has a peak during power running of the electric motor constituting the load, and the loss of the second and third semiconductor switch modules has a peak during braking of the electric motor constituting the load. In view of this, a pair of first and second semiconductor switch modules (SM1, SM2) and a pair of the third and fourth semiconductor switch modules (SM3, SM4), each having a disparity in terms of loss peak, are respectively attached to different heat receiving plates (31, 32) which are respectively common to each pair, coolers (53, 54) being attached to the heat receiving plates, whereby the heat load amounts of the coolers are leveled, thereby attaining a reduction in the size of the coolers.