Hitachi, Ltd.

Yoshio Okumura

Kyozo Tachibana

Genichi Matsumoto

Hiroshi Sato

Yoshio Nozaki

A power converter control system for use with a power converter of the type which comprises a plurality of cascade-connected converter units of which at least one converter unit is subjected to continuous control of its conduction phase angle and the remaining converter units are subjected to on-off control of their conductivity is arranged to include a master controller for instructing the number of the converter units to be rendered operative, a reversible counter operative to change its content in response to a phase controlling command applied to the continuously controlled converter unit indicating a maximum or minimum conduction phase angle or delayed phase angle in conduction, a unit change control unit for producing unit changing operation signals to be applied to the respective converter units for controlling the operation of the same, by using one of the binary bits derived from the counter without modification and decoding the remaining bits, and a comparing and identifying circuit which compares the content of the reversible counter with the output of the master controller and causing the reversible counter to operate in response to the aforementioned phase control command until the content of the same becomes identical to the output of the master controller.

Power converter control system

A power converter control apparatus comprising continuously controlled converter units and on-off controlled converter units for effecting powering control and regenerative braking control of a DC motor, which is arranged to include a unit change circuit for generating unit changing operation signals in response to a command for instructing the number of the converter units to be rendered operative from a master controllerand conduction phase signals from a phase shifter. In accordance with the unit changing operation signals, the conduction phase signals from the phase shifter are applied as a gate signal to the continuously controlled converter units in response to a powering control or a regenerative braking command, while a minimum conduction phase signal is applied as a gate signal to the on-off controlled converter units in response to a powering control command signal and a maximum conduction phase signal including a commutation marginal angle in response to a regenerative braking command signal. On the other hand, the gate signals supplied to the continuously controlled converter units may be temporarily cut off by a gate cut-off circuit and at the same time the conduction phase in the output of the phase shifter may be restored.

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Katsuta, Japan

Yoshio Okumura