UPS Eco-Mode Voltage Drop Mitigation via Thyristor Contactor Sequencing
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Solution Overview
Problem
In uninterruptible power sources with an eco-mode, switching from bypass power supply to inverter power supply results in momentary voltage drops due to the delayed response time of contactors compared to thyristor switches, affecting load stability and efficiency.
Innovation Solution
An uninterruptible power source with a semiconductor switch and contactor in the bypass circuit, controlled by a switching controller to manage the transition from eco-mode to inverter power supply, synchronizing AC voltage output from the inverter with the AC voltage source, and using threshold values to manage the switching process to minimize voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a thyristor switch and contactor are used in the bypass circuit for eco-mode power supply, then operation efficiency is improved, but momentary voltage drop occurs during switching to inverter power supply due to the longer response time of the contactor compared to the thyristor switch
Solution Approach 1:
The controller turns off the thyristor switch in advance before turning off the contactor, preparing the circuit for seamless switching. This preliminary action ensures that when the contactor opens, the thyristor switch is already non-conductive, preventing any momentary voltage drop and ensuring continuous power supply to the load.
Solution Approach 2:
The controller coordinates the switching actions of both the thyristor switch and contactor based on real-time system state monitoring. By implementing feedback control, the system adjusts the switching sequence to eliminate voltage drops while maintaining the efficiency benefits of eco-mode operation.
2Ease of manufacture
If the contactor response time is longer than the thyristor switch response time, then the bypass circuit can be constructed with standard components, but the degree of momentary voltage drop increases, affecting load stability
Solution Approach 1:
The controller implements a switching sequence where the thyristor switch is turned off before the contactor. This preliminary action compensates for the contactor's longer response time, ensuring that the bypass path is already interrupted when the contactor opens, thereby maintaining load stability without requiring specialized fast-response contactors.
3Loss of energy
If the converter and inverter are non-operational during bypass power supply, then energy loss is reduced, but switching delay occurs when transitioning to inverter power supply
Solution Approach 1:
The controller prepares the thyristor switch for immediate turn-off before the contactor opens, eliminating switching delay. This preliminary preparation ensures that the power path transition is seamless, maintaining both energy efficiency during bypass operation and rapid response capability when switching to inverter power supply.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents momentary voltage drops during the transition from eco-mode to inverter power supply, enhancing the operational efficiency and stability of the power supply to the load.
Implementation Method 1
a converter configured to rectify AC power supplied from the AC power source into DC power
Implementation Method 2
an inverter configured to invert the DC power output by the converter or DC power output by a power storage device into AC power, and to supply the AC power to the load
Data Source
AI summary
An uninterruptible power source includes an eco-mode for supplying power from an AC power source to a load via a contactor. In the eco-mode, when a degree of voltage drop of the AC power source reaches 5%, a switching controller turns on a thyristor switch and then turns off a contactor. When the degree of voltage drop of the AC power source reaches 10%, a power conversion controller is configured to cause an inverter to invert DC power of a battery into AC power, and control the inversion in the inverter to synchronize the AC voltage output from the inverter to the AC voltage supplied from the AC power source. When the inversion in the inverter is performed after turning off contactor, the switching controller is configured to turn off the thyristor switch.