3-Wire UPS Phase Segmentation for Converter Loss Reduction
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Solution Overview
Problem
Existing 3-wire UPS systems face challenges in achieving high efficiency and reducing losses, particularly in environments with good utility power quality, where they often operate in 'eco' or 'line interactive' modes, leading to inefficiencies due to the reliance on double conversion and additional losses from converter operations.
Innovation Solution
Implementing a new operational mode where one phase of the 3-wire multiphase AC source powers the load directly through a bypass switch, while the remaining two phases are powered by a converter part, allowing for independent phase control and reduced converter losses, and using advanced semiconductor switches like IGCTs for efficient switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double conversion mode is used in 3-wire UPS systems, then voltage control and isolation capabilities are maintained, but converter losses increase and efficiency decreases
Solution Approach 1:
The UPS system divides the three phases into two groups: one phase is connected directly to the load through the bypass switch (segment A), while the other two phases go through the converter part (segment B). This segmentation allows the system to maintain voltage control capabilities through the converter while reducing overall converter losses by minimizing the number of phases requiring conversion.
Solution Approach 2:
Different phases are treated differently based on local conditions. One phase is routed through the bypass for direct connection when utility power quality is good, while the other two phases undergo conversion for precise voltage control. This local quality approach optimizes efficiency by applying conversion only where necessary.
2Loss of energy
If eco mode or line interactive mode is used, then efficiency improves, but voltage control precision and isolation capabilities deteriorate
Solution Approach 1:
The system segments the phases such that one phase provides direct power connection for efficiency while the other two phases maintain voltage control precision through the converter. This segmentation allows simultaneous achievement of both eco-mode efficiency and precise voltage control.
Solution Approach 2:
The system creates an asymmetric configuration where phases are not treated equally. One phase is assigned to bypass for efficiency while two phases are assigned to converter for precision control, breaking the symmetry of traditional modes to achieve both goals simultaneously.
3Reliability
If all three phases are powered through the converter, then voltage control is maximized, but device complexity and losses increase
Solution Approach 1:
The system extracts one phase from the converter operation and connects it directly through the bypass switch. This extraction reduces converter complexity and operational burden while maintaining sufficient voltage control capabilities through the remaining two phases that pass through the converter.
Data Source
AI summary
The present application includes an uninterruptable power supply device for connection of a 3-wire multiphase AC source to a 3-wire multiphase load, whereby the UPS device is provided for multiphase operation, including a converter part, which is connected to at least one power source and the load, and a 3-wire bypass, which interconnects the AC source to the load, whereby the bypass includes a bypass switch, which includes an independently controlled switching unit for each phase of the AC source, and the UPS device includes a control unit, which controls the converter part and the bypass switch, whereby the control unit controls the bypass switch to power one of the three phases of the load directly via the bypass by one phase of the AC source, and the control unit controls the converter part to power the remaining two phases of the load. The application further includes an uninterruptible power supply system including multiple of the above UPS devices, wherein the UPS devices are connected in parallel to the load.