Communication network optical isolation circuit

摘要

An optical isolator for use in an electrically powered vehicle for interfacing between a signal processing system having a first ground and a power conversion system, which is operated responsive to control signals from the signal processing system, having a second ground that varies in potential from the first ground. A bi-directional digital communications network is provided having a first node coupled to the signal processing system for generating and receiving digital messages with respect to the first ground, and having a second node coupled to the power conversion system for receiving and generating digital messages with respect to the second ground. The bi-directional digital communications network has a unique start signal and a dominant hierarchy that allows bit-wise contention among messages for assuring communication of high priority messages between the first and second nodes within a predetermined minimum time period. The optical isolator is interposed in the communications network between the first and second nodes for transmitting the digital messages therebetween, while electrically isolating the first ground from the second ground, thereby enabling a reliable digital communications system between the first and second nodes without using a common ground system.