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Real-time Industrial Communication Protocols: A Comparative Study

Comparison of protocols
Fig. 1. Real-time industrial protocols comparison
  Communication between different levels and nodes in the power electronics systems allows the implementation of distributed control. An excellent example of that is SCC (Switching Cycle Control), where the main assumption is that GD (Gate Driver) can run PCMC (Peak current Mode Control) autonomously, and the only information needed for running it is the current reference. Flexibility is another important benefit of communication. If, for example, compared with the tra-ditional approach of running power electronics systems where PWM (Pulse Width Modulated) signal is sent from the controller to the GD, the communication allows different data to be ex-changed between GD and controller using the same or additional transmission line. Communica-tion brings hardware simplification since, for example, information collected from sensors used for gate driver protection could be implemented for control. Therefore, fewer sensors are needed for the system. Hardware and software abstraction could be achieved using communication, for example, an abstraction of power stage terminal behavior independent from hardware design (HAL – Hardware Abstraction Layer). Synchronization is the key aspect of reliable control. Communication allows synchronization protocols over communication lines such as SyncE, PTP, or state-of-the-art White Rabbit.
  Table 1 compares several industrial real-time communication protocols in an application where 100 nodes need to be controlled synchronously. The two criteria analyzed in terms of per-formance measurement are the response time (cycle time) and the jitter (that is, the variation in response time). It could be seen that most of the existing Real-Time communication protocols are based on Ethernet and that the communication speed is 100 Mbps or faster. The latest version of EtherCAT supports speed up to 10 Gbps.

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