Phase Synchronization Circuit With Dynamic Frequency Limiting
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Solution Overview
Problem
Conventional phase synchronization control circuits require a long time for AC signals to match in phase and frequency due to a minimum width of the frequency limiter's variable limit range, and rapid frequency changes in the second AC signal can negatively affect the load.
Innovation Solution
A phase synchronization control circuit that reduces the frequency limiter's limit range in response to decreasing phase difference, using a phase difference detector, frequency control unit, and limiter control unit to generate a second AC signal with controlled frequency variation, and an amount-of-change limiter to prevent rapid frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the frequency limiter's variable limit range is increased in width from minimum to maximum value in response to zero cross point detection, then frequency variation of the second AC signal is suppressed to be small, but a long period of time is required for the two AC signals to match in phase and frequency
Solution Approach 1:
The frequency limiter's variable limit range is made dynamic by adjusting its width based on the detected phase difference magnitude. When phase difference is large, the limit range width is increased to allow faster frequency adjustment. When phase difference becomes small, the limit range width is reduced to suppress frequency variation and prevent overshooting. This dynamic adjustment resolves the contradiction by adapting the limiting behavior to the current synchronization state.
Solution Approach 2:
The parameter being changed is the width of the variable limit range in the frequency limiter. This parameter is adjusted based on the phase difference between the first and second AC signals. By changing this parameter dynamically, the system achieves both fast initial synchronization (when width is large) and precise final alignment (when width is small), resolving the time vs. precision contradiction.
2Manufacturing precision
If the frequency limiter's variable limit range is set to minimum value until zero-cross point detection, then frequency variation is suppressed, but the second AC signal takes long to synchronize with the first AC signal
Solution Approach 1:
The frequency limiter transitions from a static minimum width setting to a dynamic width adjustment mechanism. The width is increased when phase difference is large to enable faster synchronization, then reduced when phase difference becomes small to achieve precise frequency matching. This dynamic behavior simultaneously improves both synchronization speed and precision.
Solution Approach 2:
The system performs preliminary frequency adjustment with a larger limit range width before transitioning to precise matching with a smaller width. This preliminary action allows the second AC signal to quickly approach the first AC signal's frequency, after which the reduced width ensures precise final alignment, thereby improving both speed and precision.
3Loss of time
If the second AC signal rapidly changes in frequency to quickly match phase and frequency, then synchronization time is reduced, but negative effects are caused to the load
Solution Approach 1:
The frequency limiter's variable limit range width is adjusted based on the phase difference between signals. When phase difference is large, the width is increased to permit rapid frequency changes for quick synchronization. When phase difference becomes small, the width is reduced to prevent rapid changes that would cause load impact. This parameter adjustment resolves the contradiction between synchronization speed and load protection.
Solution Approach 2:
The system dynamically adjusts the frequency change constraints based on the current synchronization state. Early in the synchronization process, larger frequency changes are permitted to reduce synchronization time. As synchronization approaches completion, frequency changes are constrained to prevent load impact from rapid transitions. This dynamic constraint adjustment achieves both fast synchronization and load protection.
Data Source
AI summary
A phase synchronization control circuit includes: a phase difference detector that detects a phase difference between AC voltage and an AC signal, a frequency control circuitry that generates a first frequency control value to eliminate the phase difference, a frequency limiter that limits the first frequency control value to fall within a variable limit range to generate a second frequency control value, a limiter control circuitry that sets the variable limit range based on the phase difference and reduces the variable limit range in width in response to the phase difference decreasing, and an oscillator that generates the AC signal with a frequency of a value corresponding to the second frequency control value. This can suppress overshooting of the AC signal in frequency to be small.