UPS Capacitor Voltage Control During Inverter-Bypass Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In uninterruptible power supply apparatuses, high-speed control of feedback components leads to unstable voltage regulation, causing terminal-to-terminal voltage of capacitors to exceed upper limits when load current changes suddenly, especially in lap power feed mode where both inverter and bypass AC power supplies are used.
Innovation Solution
Incorporating a rectifier, capacitor, inverter, switches, and controllers that manage AC currents with feedback and feed-forward components to stabilize voltage control, using different gains for feedback and feed-forward components during mode switching to prevent voltage exceedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed control of feedback component is used to maintain capacitor voltage, then voltage regulation responds quickly to load changes, but control becomes unstable and voltage exceeds upper limit
Solution Approach 1:
The patent applies dynamics by making the feedback control gain variable rather than fixed. The gain is adjusted dynamically based on the operating mode (inverter power feed mode, bypass power feed mode, or lap power feed mode) and the magnitude of load current changes. This allows the system to respond quickly when needed while maintaining stability under different conditions, resolving the contradiction between fast response and stable control.
Solution Approach 2:
The patent changes the parameter of feedback control gain based on operating conditions. By adjusting the gain parameter according to the power feed mode and load current变化, the system achieves both fast response when load changes suddenly and stable control during normal operation, preventing voltage from exceeding the upper limit while maintaining adequate response speed.
2Stability of the object's composition
If feed forward component is added to address sudden load current changes, then control stability improves, but output from rectifier becomes greater than inverter output, causing capacitor voltage to exceed upper limit in lap power feed mode
Solution Approach 1:
The patent applies local quality by implementing different feed forward control strategies for different power feed modes. In inverter power feed mode, full feed forward control is applied to handle sudden load changes. In lap power feed mode, the feed forward component is restricted or reduced to prevent overcharging the capacitor. This localized adaptation of control quality resolves the contradiction between stability and voltage control.
Solution Approach 2:
The patent dynamically adjusts the feed forward component based on the operating mode. The control system activates different levels of feed forward control depending on whether the system is in inverter power feed mode, bypass power feed mode, or lap power feed mode. This dynamic adjustment ensures stability while preventing harmful voltage exceedance in specific modes.
3Reliability
If both inverter and bypass AC power supply are used in lap power feed mode, then power supply redundancy is achieved, but rectifier output exceeds inverter output, causing capacitor voltage to exceed upper limit
Solution Approach 1:
The patent applies local quality by implementing mode-specific control strategies. In lap power feed mode, the control system recognizes the dual-power-source condition and adjusts the feed forward component accordingly to prevent overcharging. This localized control adaptation maintains the reliability benefit of redundant power supply while eliminating the harmful voltage exceedance effect.
Solution Approach 2:
The patent uses feedback control to monitor capacitor voltage and adjust the rectifier output accordingly. In lap power feed mode, the feedback mechanism ensures that the combined output from both inverter and bypass power supply does not cause the capacitor voltage to exceed the upper limit, maintaining reliability while preventing voltage exceedance.
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
Stabilizes voltage control by low-speed feedback regulation and addresses sudden load changes with feed-forward components, preventing terminal-to-terminal voltage from exceeding upper limits in lap power feed mode.
Implementation Method 1
a rectifier that converts first AC voltage supplied from a commercial AC power supply to DC voltage
Implementation Method 2
a capacitor that smooths DC output voltage from the rectifier
Implementation Method 3
an inverter that converts terminal-to-terminal voltage of the capacitor to second AC voltage
Data Source
AI summary
In an uninterruptible power supply apparatus, AC current, which includes a feedback component having a value corresponding to deviation between terminal-to-terminal voltage of a capacitor and reference voltage, and a feed forward component obtained by multiplying load current by a gain, is passed into a converter such that the terminal-to-terminal voltage of the capacitor becomes the reference voltage. The gain is set to a first gain in an inverter power feed mode and a bypass power feed mode, and the gain is set to a second gain smaller than the first gain in a switching period of switching between the inverter power feed mode and the bypass power feed mode, to prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage in a lap power feed mode.