Toshiba International Corporation

Osamu Tanaka

John David Kleinecke

Michael C Daskalos

An 18n-pulse rectifier for AC drive systems having a separate DC bus for each output phase is described, where n=any positive integer. The rectifier uses three separate phase rectifiers, one for each output phase of a transformer, each comprised of n six-pulse diode bridges connected in series or parallel. Each phase rectifier may be supplied with n unique sets of phase inputs from a transformer secondary winding. In some configurations, the n sets of inputs provided to each rectifier are separated by 60/n degrees of phase (when n is greater than 1), while the corresponding inputs to neighboring rectifiers are separated by 20/n degrees of phase. In a 36-pulse example, the phase offsets for the inputs provided to the rectifiers may be &#x2212;25&#xb0; and +5&#xb0; from the transformer primary winding (for the first rectifier), &#x2212;15&#xb0; and +15&#xb0; from the primary winding (for the second rectifier) and &#x2212;5&#xb0; and +25&#xb0; from the primary winding (for the third rectifier). Each set of inputs may include three lines of in-phase current, and may be coupled to one of the six-pulse diode bridges.

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Kunitachi, Japan

Osamu Tanaka