Inverter Output Voltage Control for UPS Efficiency
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Solution Overview
Problem
Conventional uninterruptible power supply apparatuses have efficiency issues due to a fixed output voltage, resulting in lower efficiency when the load capacity to rated capacity ratio deviates from a predetermined value.
Innovation Solution
An uninterruptible power supply apparatus with a control device that adjusts the output voltage and load current within allowable input voltage ranges to optimize efficiency based on the load capacity to rated capacity ratio, increasing efficiency by decreasing output voltage and increasing load current when the ratio is lower, and increasing output voltage and decreasing load current when the ratio is higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage of the inverter is fixed to a constant rated voltage, then the uninterruptible power supply apparatus can operate reliably, but the efficiency is lower when the load capacity to rated capacity ratio deviates from the predetermined value
Solution Approach 1:
The patent applies dynamics by making the output voltage of the inverter adjustable rather than fixed. The control device dynamically changes the output voltage based on the load capacity to rated capacity ratio, allowing the system to adapt to varying load conditions and maintain high efficiency across different operating points while ensuring reliable operation within the allowable input voltage range of the load.
Solution Approach 2:
The patent applies parameter changes by modifying the output voltage parameter of the inverter based on the load condition. When the load capacity to rated capacity ratio is lower than the predetermined value, the control device decreases the output voltage to increase efficiency. When the ratio is higher, the control device increases the output voltage. This parameter adjustment resolves the contradiction between maintaining constant rated voltage for reliability and optimizing efficiency under varying load conditions.
2Loss of energy
If the output voltage of the inverter is decreased to increase efficiency when the load capacity ratio is low, then the efficiency improves, but the output voltage deviates from the constant rated voltage
Solution Approach 1:
The system transitions from a static constant rated voltage to a dynamic voltage output that adapts to load conditions. The control device continuously monitors the load capacity to rated capacity ratio and adjusts the output voltage accordingly, maintaining efficiency optimization while ensuring the voltage remains within the allowable input voltage range of the load.
Solution Approach 2:
The output voltage parameter is changed based on load conditions. When the load capacity ratio is lower than the predetermined value, the control device decreases the output voltage to increase efficiency. This parameter change is controlled and bounded to remain within the allowable input voltage range, resolving the contradiction between efficiency improvement and constant rated voltage requirement.
3Adaptability or versatility
If the load capacity to rated capacity ratio is not at the predetermined value, then the system can operate under varying load conditions, but the efficiency is lower than the maximum value
Solution Approach 1:
The patent applies dynamics by making the output voltage adjustable based on the load condition. The control device dynamically modifies the output voltage to match the actual load capacity to rated capacity ratio, allowing the system to maintain high efficiency under varying load conditions rather than being limited to operation only at the predetermined ratio.
Solution Approach 2:
The control device changes the output voltage parameter according to the load capacity ratio. When the ratio is lower than the predetermined value, the output voltage is decreased to increase efficiency. When the ratio is higher, the output voltage is increased. This parameter adjustment enables the system to maintain high efficiency across a wide range of load conditions, resolving the contradiction between load adaptability and efficiency.
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
Enhances efficiency by dynamically controlling output voltage and load current, improving power supply performance compared to conventional systems with fixed output voltage.
Implementation Method 1
a converter configured to convert AC power supplied from a commercial AC power source into DC power
Implementation Method 2
an inverter configured to convert DC power into AC power and supply the converted power to a load
Data Source
Figure 1
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AI summary
An uninterruptible power supply apparatus includes a converter (5) configured to convert AC power into DC power, and an inverter (10) configured to convert DC power into AC power and supply the converted power to a load (24). The load (24) is configured to receive an AC voltage within a range of allowable input voltage to consume constant AC power. The uninterruptible power supply apparatus has maximum efficiency η when a ratio of load capacity to rated capacity of the uninterruptible power supply apparatus is a predetermined value α. The uninterruptible power supply apparatus further includes a control device (18) configured to control an output voltage of the inverter (10) within the range of allowable input voltage so as to increase the efficiency η, when the ratio of the load capacity to the rated capacity is different from the predetermined value α.