Single-Inductor UPS Topology for Loss Reduction
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Solution Overview
Problem
Conventional uninterruptible power supplies (UPS) face inefficiencies in power conversion and battery charging, particularly in managing AC and DC power transitions, which can lead to reduced performance and increased losses during backup operations.
Innovation Solution
A power conversion circuit with a single inductor and multiple switch devices, including a bypass relay, that alternately charges and discharges the inductor through different current paths based on AC input power polarity, and during backup mode, generates positive and negative DC output voltages using energy stored in the inductor, optimizing energy transfer and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power conversion circuits are used with multiple inductors and standard switching paths, then the circuit can provide stable power conversion, but the inductor utilization is low and conduction losses are high
Solution Approach 1:
The patent combines multiple inductor functions into a single shared inductor that serves both rectifier and inverter operations. The inductor is alternately connected to the AC input during rectifier mode and to the DC output during inverter mode, eliminating the need for separate inductors for each function and thereby reducing conduction losses while maximizing inductor utilization.
Solution Approach 2:
The patent employs dynamic switching of the inductor connections through control of switching devices. The inductor is dynamically reconfigured between different circuit paths depending on whether the system is in rectifier mode or inverter mode, allowing optimal performance in both operating states while minimizing energy losses.
2Loss of energy
If standard switching devices are used in series with the inductor, then the circuit provides reliable power conversion, but semiconductor drops increase conduction losses
Solution Approach 1:
The patent extracts the bypass function from the main current path by introducing a bypass relay that creates an alternative path around the switching devices during certain operating conditions. This removes the semiconductor voltage drops from the critical power conversion path while maintaining the reliability of the switching devices for control functions.
Solution Approach 2:
The bypass relay acts as an intermediary element that mediates between the need for reliable switching control and the desire to minimize conduction losses. By introducing this intermediate bypass path, the system can achieve low-loss operation during specific modes while retaining the reliability benefits of controlled switching when needed.
3Productivity
If the power conversion circuit uses a single shared inductor for both rectifier and inverter, then inductor utilization improves and losses reduce, but the circuit complexity increases
Solution Approach 1:
The patent makes the single inductor universal by designing it to perform both rectifier and inverter functions. The inductor is connected to circuit nodes that allow it to be alternately used in both power conversion modes, eliminating the need for multiple specialized inductors and reducing overall circuit complexity despite the shared resource.
Solution Approach 2:
The patent implements preliminary action through the bypass relay and switching control that prepares the circuit paths in advance for mode transitions. The switching devices and bypass relay are configured to preemptively establish the correct current paths before mode changes occur, smoothing the transition between rectifier and inverter operations and reducing the perceived complexity of managing the shared inductor.
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
This configuration enhances inductor utilization, reduces semiconductor drops, and minimizes conduction losses, resulting in improved efficiency and reliability during both line and backup power operations.
Implementation Method 1
The power conversion circuit has an inductor, a first switch device coupled in series with the inductor... The power conversion circuit is operable to charge the inductor and generate the positive and negative DC output voltages
Data Source
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AI summary
A power converter includes a first power input to receive AC input power, a second power input to receive backup power, a first DC bus configured to provide a positive DC output voltage, a second DC bus configured to provide a negative DC output voltage, and a power conversion circuit coupled to the first DC bus and the second DC bus. The power conversion circuit has an inductor, a first switch device coupled in series with the inductor, a second switch device coupled in series with the first switch device, and a bypass relay coupled in parallel with the second switch device. The power conversion circuit is switchably coupled to the first power input and the second power input, and is operable to charge the inductor and generate the positive and negative DC output voltages.