Auxiliary Power Conversion Device for Uninterruptible Supply
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Solution Overview
Problem
Conventional uninterruptible power supply systems with both regular and auxiliary devices are large and costly, and replacing the auxiliary device with a simple power conversion device leads to output voltage decreases when AC voltage varies, causing load operation to stop.
Innovation Solution
An uninterruptible power supply system incorporating a regular uninterruptible power supply device and an auxiliary power conversion device that converts AC power to DC and back to AC without using a battery, with a first converter, inverter, and control device to manage output voltage by adjusting waveform and frequency based on DC voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple power conversion device without battery is used to replace the auxiliary uninterruptible power supply device, then the system size and cost are reduced, but the output voltage decreases when AC voltage varies, causing load operation to stop
Solution Approach 1:
The patent applies dynamics by making the switching frequency of the inverter adjustable rather than fixed. The control device dynamically changes the switching frequency based on the DC voltage level to maintain stable AC output voltage despite variations in AC input voltage, thereby resolving the contradiction between simplified device structure and reliable continuous operation
Solution Approach 2:
The patent changes the parameter of switching frequency to adapt to varying DC voltage conditions. When AC voltage varies causing DC voltage to change, the control device adjusts the switching frequency parameter to compensate and maintain stable output voltage, ensuring continuous load operation while using a simplified power conversion device
2Device complexity
If a simple power conversion device without battery is used to replace the auxiliary uninterruptible power supply device, then the system cost is reduced, but the output voltage decreases when AC voltage varies, causing load operation to stop
Solution Approach 1:
The patent applies dynamics by making the switching frequency of the inverter adjustable rather than fixed. The control device dynamically changes the switching frequency based on the DC voltage level to maintain stable AC output voltage despite variations in AC input voltage, thereby resolving the contradiction between simplified device structure and reliable continuous operation
Solution Approach 2:
The patent changes the parameter of switching frequency to adapt to varying DC voltage conditions. When AC voltage varies causing DC voltage to change, the control device adjusts the switching frequency parameter to compensate and maintain stable output voltage, ensuring continuous load operation while using a simplified power conversion device
3Stability of the object's composition
If the switching frequency is decreased to reduce waveform distortion, then the output voltage stability improves, but the power conversion efficiency decreases
Solution Approach 1:
The patent optimizes the switching frequency parameter within a specific range (20 kHz to 50 kHz) to achieve the best balance between output voltage stability and power conversion efficiency. By carefully selecting and adjusting this parameter, the system maintains stable output voltage while minimizing energy losses
Solution Approach 2:
The patent applies partial action by using a simplified power conversion device without battery for the auxiliary function, accepting some waveform distortion but compensating through controlled switching frequency adjustment to maintain adequate output voltage stability for continuous load operation
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
The system reduces size and cost while maintaining load operation even with varying AC voltage, generating acceptable waveform distortion to ensure continuous operation.
Implementation Method 1
a first converter (24) configured to convert the AC power supplied from the second AC power supply (PS2) into the DC power
Implementation Method 2
a first inverter (27) configured to convert the DC power generated by the first converter (24) into the AC power
Data Source
Figure 1
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Figure 3
AI summary
An uninterruptible power supply system includes a regular uninterruptible power supply device (Un) configured to supply AC power to a load (LDn), and an auxiliary power conversion device (B1) configured to supply AC power to the load (LDn) when the regular uninterruptible power supply device (Un) has a failure. The auxiliary power conversion device (B1) includes a converter (24) and an inverter (27). When a DC voltage (VDC2) generated by the converter (24) is higher than a lower limit voltage (VL), the auxiliary power conversion device (B1) outputs an AC voltage (VO) having a sinusoidal wave and falling within an acceptable input voltage range of the load (LDn). When the DC voltage (VDC2) is lower than the lower limit voltage (VL), the auxiliary power conversion device (B1) outputs an AC voltage (VO) having waveform distortion within an acceptable range for the load (LDn) and falling within the acceptable input voltage range of the load (LDn).