PFC and DC-DC Multiplexing Converter Without Clamping Diodes
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) with multiplexed AC-DC power factor control (PFC) and DC-DC circuits face issues of electromagnetic compatibility (EMC) problems and inductor overheating due to high-frequency potential jumping and low inductor utilization, especially when using clamping diodes.
Innovation Solution
A power factor correction and DC-DC multiplexing converter design that includes a single inductor, mechanical switches, semiconductor switches, and rectifier bridge arms, eliminating the need for clamping diodes and ensuring stable potential differences, thereby improving EMC and inductor utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clamping diodes are added to address high-frequency potential jumping and improve EMC, then EMC performance is improved, but one inductor is shorted causing inductor overheating and reduced inductor utilization
Solution Approach 1:
The patent removes the clamping diodes from the circuit configuration. By extracting these diodes that were causing the inductor shorting issue, the solution eliminates the root cause of inductor overheating while maintaining EMC performance through an alternative circuit topology that avoids high-frequency potential jumping on battery lines.
Solution Approach 2:
Instead of adding clamping diodes to suppress high-frequency potential jumping (the conventional approach), the patent inverts the approach by redesigning the circuit topology to inherently avoid the problem. The multiplexing converter uses a different switching configuration that prevents high-frequency potential jumping without requiring clamping diodes, thus avoiding inductor shorting and overheating.
2Reliability
If clamping diodes are added to improve EMC, then EMC performance is improved, but inductor utilization is reduced
Solution Approach 1:
The patent extracts/removes the clamping diodes that were causing the inductor to be shorted during part of the operating cycle. This removal restores the inductor's full functionality and utilization while maintaining EMC performance through the alternative multiplexing converter topology.
Solution Approach 2:
The patent implements a multiplexing converter where a single inductor serves multiple functions: it operates as the main energy storage inductor during AC-DC conversion and also functions during DC-DC battery discharge without being shorted. The circuit topology enables the inductor to be fully utilized across different operating modes without requiring separate clamping diodes.
3Device complexity
If a single inductor is used in multiplexing design, then device complexity and cost are reduced, but inductor utilization is low and overheating occurs
Solution Approach 1:
The patent designs the multiplexing converter so that the single inductor performs multiple functions across different operating modes. During AC-DC power factor correction mode, the inductor stores energy and enables PFC operation. During DC-DC battery discharge mode, the same inductor continues to function as an energy storage element without being shorted, achieving full utilization. This multi-functionality maintains simplicity while avoiding overheating.
Solution Approach 2:
The patent employs dynamic switching control where semiconductor switches dynamically reconfigure the circuit topology between AC-DC and DC-DC modes. This dynamic reconfiguration ensures the inductor is always actively utilized in its appropriate role for each mode, preventing the inductor from being shorted or underutilized, thereby maintaining high inductor utilization without increasing device complexity.
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 design achieves improved EMC performance and reduces inductor overheating, saving costs and space by utilizing a single inductor effectively, while maintaining stable potential differences during battery discharge mode.
Implementation Method 1
an inductor L1, one end of which is connected to the mains supply through the first mechanical switch RY1, and connected to a positive electrode of the battery B21 through the second mechanical switch RY2
Implementation Method 2
a first rectifier bridge arm 213, connected between the first node N1 and the second node N2, where the first rectifier bridge arm 213 has a first intermediate node N3
Implementation Method 3
a first capacitor C211, connected between the positive direct current bus 211 and the neutral point N5; a second capacitor C212, connected between the neutral point N5 and the negative direct current bus 212
Data Source
AI summary
A power factor correction and direct current (DC)-DC multiplexing converter is provided. One end of an inductor is selectively connected to a mains supply or a positive electrode of a battery. A first rectifier bridge arm with a first intermediate node and a second rectifier bridge arm with a second intermediate node are separately connected between a first node and a second node, the first intermediate node is connected to the other end of the inductor, and the second intermediate node is connected to a neutral point. A first semiconductor switch controls conduction between the first node and the second node. A second semiconductor switch controls conduction between the second node and a negative direct current bus. A third semiconductor switch controls conduction between the neutral point and a negative electrode of the battery. The positive and negative direct current buses are configured to provide a direct current output.