Line-Interactive UPS Mode Switching to Prevent Relay Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing line-interactive UPSs face issues with switch adhesion and high production costs due to the need for relays with high current withstand values and good bounce performance when switching between boost and buck modes, which reduces the service life and reliability of the UPS.
Innovation Solution
A state switching method that maintains the connected state of the voltage regulation circuit during mode transitions, disconnects and reconnects the appropriate circuits to avoid high current disconnection, and uses phase lock operations to ensure smooth transitions, allowing for the use of ordinary relays and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a relay is directly turned off for circuit switching when switching between boost and buck modes, then the switching speed is fast, but adhesion occurs in the relay which impairs the service life of the UPS
Solution Approach 1:
The patent applies preliminary action by switching the relay to battery mode before actually disconnecting the voltage regulation circuit. The method first operates the first switch to switch from current first mode to battery mode, maintaining the connected state of the first voltage regulation circuit. After entering battery mode, the second switch is turned off to disconnect the first voltage regulation circuit. This preliminary mode switching ensures that when the relay disconnects the circuit, the current is already reduced or zero, preventing adhesion and extending relay service life while maintaining fast switching performance
2Reliability
If a relay with large current withstand value and good bounce performance is used, then switch adhesion is avoided, but the production cost of the UPS increases
Solution Approach 1:
The patent applies parameter changes by altering the operational parameters of the relay rather than changing the relay's physical specifications. By changing the switching sequence and timing parameters - switching to battery mode before disconnecting the circuit - the relay operates under different electrical conditions (reduced current, different voltage states) that prevent adhesion. This allows the use of ordinary, cost-effective relays instead of expensive high-specification relays, reducing production costs while maintaining reliability
3Productivity
If the voltage regulation circuit is disconnected during mode switching, then the switching between modes is clean and efficient, but high current passes through the relay causing adhesion
Solution Approach 1:
The patent applies preliminary action by performing the mode switch to battery mode before disconnecting the voltage regulation circuit. This preliminary action changes the operational state while maintaining circuit connection, allowing the subsequent disconnection to occur under low or zero current conditions. The method operates the first switch to battery mode first, then turns off the second switch to disconnect the first voltage regulation circuit, ensuring clean efficient switching without high current adhesion problems
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosure provides a state switching method for a line-interactive UPS and an UPS using the same. The state switching method includes: when the UPS needs to switch from a first mode to a second mode, operating a first switch to switch from the current first mode to a battery mode, and maintaining the connected state of a first voltage regulation circuit in the switching process; after entering the battery mode, turning off a second switch to cause the first voltage regulation circuit disconnected from the UPS, and then turning on a third switch to cause a second voltage regulation circuit connected to the UPS; and operating the first switch to cause the UPS switched from the battery mode to the second mode. The switches of the UPS can be disconnected in a case of low current or no current, which can avoid switch adhesion, improve the reliability of the UPS, and prolong the service life of the UPS.