Frequency Converter Bypass Synchronization Control
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Solution Overview
Problem
Existing bypass frequency conversion control systems for AC motors, such as those in escalators, face challenges in smooth power supply switching, leading to surge currents and motor jitter due to inadequate synchronization of voltage signals during transitions from frequency converter power to network voltage power.
Innovation Solution
A frequency converter and bypass frequency conversion control system that tracks and synchronizes the frequency and phase of the network voltage signal with its output voltage signal, allowing for seamless switching between power sources, reducing surge currents and motor jitter by issuing a switching instruction when synchronization is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a synchronizer is used to sample and monitor voltage signals for synchronization, then smooth switching between power sources is achieved, but device complexity increases
Solution Approach 1:
The patent combines the synchronizer, frequency converter, and switching control into an integrated control system. The synchronizer and frequency converter share common control circuits and processing units, allowing them to work cooperatively without requiring separate independent systems. This merging reduces overall device complexity while maintaining the synchronization and smooth switching functions.
Solution Approach 2:
The control system is designed with multi-functional components that can perform multiple tasks. The frequency converter not only converts frequency but also participates in synchronization monitoring and switching control. The synchronizer works jointly with the frequency converter for both synchronization detection and switching execution, reducing the need for dedicated separate components and simplifying the overall system structure.
2Productivity
If rapid switching between power sources is implemented, then productivity is improved, but surge current and motor jitter increase
Solution Approach 1:
The system performs preliminary synchronization monitoring before executing the switching action. The synchronizer continuously monitors the voltage signals and determines when synchronization conditions are met before triggering the frequency converter to switch power sources. This preliminary detection and preparation phase ensures that switching occurs at the optimal moment, enabling rapid transition while avoiding surge currents and motor jitter by switching only when voltages are synchronized.
Solution Approach 2:
The system employs feedback control where the synchronizer continuously monitors the voltage signals from both power sources and provides real-time information to the frequency converter. Based on this feedback about synchronization status, the frequency converter adjusts its switching timing to achieve rapid yet smooth power transition. The feedback mechanism ensures that switching occurs only when synchronization conditions are satisfied, preventing harmful surge currents while maintaining high switching speed.
Data Source
AI summary
This invention provides a frequency converter and bypass frequency conversion control system, and its switching control method, belonging to the technical field of motor drive control. The frequency converter of this invention accesses a network voltage signal with a corresponding first frequency and first phase, wherein the frequency converter is configured to be able to operate in tracking and synchronization mode, and in tracking and synchronization mode, the frequency converter tracks the first frequency and first phase of the network voltage signal in order to basically synchronize the second frequency and second phase of its output voltage signal with the first frequency and corresponding first phase of the network voltage signal. The frequency converter of this invention achieves simple, low cost, fast synchronization with good synchronism.