ASD Switching Synchronization Using Vector Control
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Solution Overview
Problem
Current methods for switching the power supply of electric machines between an adjustable speed drive (ASD) and an electrical network are slow, taking around 30 seconds, which can lead to overheating and require cooling measures, especially for ASDs that operate within this timeframe.
Innovation Solution
A process utilizing vector control methods to synchronize voltage and phase differences between the ASD and the electrical network, allowing for rapid switching by controlling switches and adjusting current levels, achieving synchronization within 1-2 seconds by ensuring phase and amplitude errors are less than 2 degrees and 2% respectively, enabling simultaneous power supply from both sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a synchro-check relay and synchronisation unit are used to synchronize voltage and phase between ASD and network, then switching safety is improved, but synchronization time increases to around 30 seconds
Solution Approach 1:
The patent replaces the traditional mechanical/electrical synchro-check relay system with a microprocessor-based control system that uses software algorithms to calculate and adjust phase and voltage synchronization. This substitution enables much faster synchronization (reducing time from 30 seconds to under 5 seconds) while maintaining switching safety through precise digital control of the switching elements.
Solution Approach 2:
The invention changes the control parameters from manual or relay-based mechanical adjustments to microprocessor-controlled electrical parameter adjustments. The system continuously monitors and dynamically adjusts voltage magnitude, frequency, and phase angle parameters, enabling rapid convergence to synchronized states without the time delays inherent in traditional relay-based systems.
2Reliability
If synchronization takes 30 seconds, then thorough voltage and phase alignment is achieved, but ASD components overheat requiring water cooling
Solution Approach 1:
The microprocessor control system performs preliminary calculations of the required voltage and phase adjustments before actual switching occurs. By pre-computing the synchronization parameters and preparing the switching elements in advance, the system achieves accurate voltage alignment in under 5 seconds, preventing the prolonged operation that would cause overheating.
Solution Approach 2:
The invention rushes through the synchronization process by using rapid microprocessor-based calculations and control, completing the voltage and phase alignment in under 5 seconds instead of 30 seconds. This accelerated process skips the time period that would otherwise allow heat accumulation in ASD components, eliminating the need for water cooling.
3Reliability
If traditional synchro-check relay method is used, then switching safety is maintained, but switching speed is too slow for certain ASD applications
Solution Approach 1:
The patent replaces the mechanical synchro-check relay system with a microprocessor-based control system that uses software algorithms to calculate and adjust phase and voltage synchronization. This substitution enables much faster synchronization (reducing time from 30 seconds to under 5 seconds) while maintaining switching safety through precise digital control of the switching elements.
Solution Approach 2:
The system continuously monitors voltage, frequency, and phase parameters and uses feedback control to dynamically adjust the ASD output. The microprocessor receives real-time measurements, compares them with target values, and automatically adjusts the switching elements to maintain synchronization, enabling both high speed and high reliability.
Data Source
Figure 1
Figure 2~3
AI summary
A process for switching the voltage supply (12) for an alternating current electric machine (16) between a supply from an ASD (32) and a supply from an electrical network (22) is described. The process comprises a stage for determining an ideal speed of rotation for the electric machine (16) and for synchronising the phase and the amplitude of the voltage delivered by the ASD (32) with the voltage delivered by the electrical network (22).