Synchronization system and synchronization method of multisystem control apparatus

摘要

In a synchronization system adopted in a synchronous-multisystem control apparatus comprising a plurality of systems operating synchronously with each other at a fixed control period, the synchronous-multisystem control apparatus can be operated in a single-system mode in the event of failures occurring simultaneously in some of the systems. The synchronous-multisystem control apparatus employs a plurality of control circuits each provided for one of the systems. Any particular one of the control circuits comprises: a period-signal generating circuit for generating a period signal indicating a start point of a control period; a synchronization-reference selecting circuit for outputting a synchronization-reference signal by referring to period signals generated by the systems; and a control-period correcting circuit for correcting a control period of the particular system by forming a judgment on a synchronization shift of the period signal generated by the particular system from the synchronization-reference signal and keeping the control period as it is in case the synchronization-reference signal is not generated.