Asynchronous Timer Synchronization via Event-Triggered Telegrams
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Solution Overview
Problem
Existing methods for determining the time difference between events recorded by devices with asynchronous timers require high-precision clock generators, which are expensive and complex, leading to increased load on serial connections and synchronization challenges, especially when synchronizing voltage and current measurements in AC circuits.
Innovation Solution
A method that records the timer values of events in each device and uses a synchronization telegram to calculate the time difference between events, allowing for asynchronous operation and reducing the need for high-precision clock synchronization, using inexpensive standard components and minimizing communication load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-precision clock generators are used to synchronize time bases of devices, then time measurement precision is improved, but device cost and complexity increase
Solution Approach 1:
The patent replaces expensive high-precision clock generators with inexpensive standard clock components. Instead of requiring precise time base synchronization, the system uses a one-way synchronization telegram that is sent only when needed to establish a reference point, eliminating the need for continuously running precise clocks in both devices.
Solution Approach 2:
The patent extracts the synchronization requirement from the time bases themselves and relocates it to the event timing mechanism. Rather than synchronizing the clock generators, the system extracts only the necessary timing information through selective event marking and one-directional synchronization telegrams.
2Measurement precision
If frequent resynchronization is performed to maintain time accuracy, then time measurement precision is improved, but communication load increases
Solution Approach 1:
The patent implements periodic event-based synchronization where synchronization telegrams are sent only when specific events occur (such as zero crossings in AC circuits), rather than continuously or at fixed intervals. This reduces communication load while maintaining adequate synchronization for the application requirements.
Solution Approach 2:
The system allows each device to independently record event times using its own local clock without requiring continuous external synchronization. The synchronization telegram is only invoked when needed to establish a reference relationship between the two devices' time bases.
3Measurement precision
If synchronous clock operation is enforced with maximum offset of less than 100μs, then time measurement precision is improved, but component cost increases
Solution Approach 1:
The patent uses inexpensive standard clock components instead of expensive precision oscillators. The system accepts that these cheap clocks will drift apart over time, but compensates by establishing a fresh time reference through synchronization telegrams only when events need to be correlated, rather than requiring continuous precision.
Solution Approach 2:
The patent changes the approach from maintaining a fixed time offset parameter (less than 100μs) to allowing variable offset that is periodically corrected through event-based synchronization. This parameter change enables the use of lower-cost components that cannot maintain strict timing bounds.
Data Source
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AI summary
The method involves connecting first and second devices (1,2) such as motor controller and separate voltage measurement module together via serial communication link. A first time of occurrence of second event in second apparatus is detected and stored. A synchronization message (4) is generated in first device, if first event is detected in or from first apparatus. A second time of synchronization message arrival is stored in second device. The delay time difference between message generation and message arrival detection is determined based on time difference between events. Independent claims are included for the following: (1) system for determining time difference between events recorded in or from first device, and second event to be detected in second device; and (2) computer program for determining time difference between events recorded in or from first device, and second event to be detected in second device.