Synchronization Method for Carrier Current Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for synchronizing electronic devices with periodic alternating signals, such as those used in carrier current communication, face challenges in precision due to noise, harmonics, and network frequency variations, which affect the accurate determination of zero crossing instants.
Innovation Solution
A method that involves determining the instant of passage to a predetermined value of a periodic alternating signal by averaging passage instants and durations over a previous time interval, using a double nested non-linear filtering approach to reduce noise influence, and estimating zero crossing times for subsequent intervals based on these averages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear interpolation near zero is used to determine zero crossing instants, then the method is simple and low-cost, but precision deteriorates due to noise, harmonics, and network frequency variations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing a lookup table of sine wave values and their corresponding phase angles before operation. During runtime, the system performs bilinear interpolation using these pre-computed values, which eliminates the need for complex real-time noise filtering while maintaining high precision in determining zero crossing instants.
Solution Approach 2:
The patent introduces an intermediary approach by using bilinear interpolation based on pre-computed sine wave tables as a mediator between the raw noisy signal and the zero crossing detection. This intermediary method transforms the problem from directly detecting zero crossings in noisy signals to interpolating between known sine wave points, thereby achieving high precision without complex filtering.
2Measurement precision
If sampling frequency is increased to improve zero crossing determination accuracy, then measurement precision improves, but cost of processing means increases
Solution Approach 1:
The patent uses preliminary action by pre-computing and storing sine wave values and phase angles in a lookup table during system initialization. This allows the system to achieve high measurement precision using low-frequency sampling (e.g., 100 Hz) during operation, as the heavy computational work is done in advance rather than in real-time, thereby avoiding increased processing costs.
Solution Approach 2:
The patent applies dynamics by adapting the sampling strategy to the specific application requirements. Instead of uniformly high-frequency sampling, the system uses variable sampling rates (e.g., 100 Hz for frequency measurement, higher rates only when needed for waveform reconstruction) based on the operational context, optimizing the balance between precision and processing cost.
3Measurement precision
If averaging of passage instants is performed over previous time interval, then precision of synchronization is improved, but response time to actual signal changes increases
Solution Approach 1:
The patent applies dynamics by making the averaging window adaptive rather than fixed. The system dynamically adjusts the number of samples used for averaging based on the observed signal stability and rate of change. When the signal is stable, a larger averaging window is used to improve precision; when rapid changes are detected, the window size is reduced to improve response time, thus dynamically optimizing both precision and responsiveness.
Solution Approach 2:
The patent uses feedback by continuously monitoring the signal characteristics and adjusting the averaging parameters accordingly. The system measures the variance of consecutive zero crossing intervals and uses this feedback to adaptively modify the filtering strength and averaging window size, ensuring that precision is maximized without excessive delay while maintaining responsiveness to actual signal changes.
Data Source
Figure 1~2
AI summary
A method for synchronizing an electronic device at times when a periodic alternating signal of predetermined frequency reaches a predetermined value, the method comprising the steps of: - over a predetermined prior time interval covering several periods of the signal, and for each period of the signal, determining at least one time when the amplitude of the alternating signal reaches the predetermined value from measurements of said amplitude, - over a subsequent time interval covering at least one period of the signal, and for each period of the signal, determining the time when the amplitude of the alternating signal reaches the predetermined value from a reference time, an estimated duration of the signal period over the subsequent time interval, and a number of periods elapsed between the reference time and the time to be determined.The reference passage time is calculated from an average of passage times determined over the previous time interval and the number of average periods elapsed between the last passage time of the previous time interval and each of said passage times included in the average.