Transformerless Power Conversion Apparatus Loop Current Prevention
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Solution Overview
Problem
Conventional power conversion apparatuses that prevent loop current flow using transformers are costly.
Innovation Solution
A power conversion apparatus with a converter generating DC voltages, capacitors to regulate voltage, and a controller managing transistor operation based on comparator signals to prevent loop current without a transformer, ensuring cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used to prevent loop current flow, then loop current is prevented, but device cost increases
Solution Approach 1:
The invention extracts and removes the transformer component from the power conversion apparatus. By using a converter with controlled transistors and capacitors instead, the harmful loop current is prevented without requiring the expensive transformer, thus resolving the contradiction between reliability and device cost
Solution Approach 2:
The invention replaces the magnetic-based transformer system with an electronic control system using transistors (Q1-Q6), diodes (D1-D6), and capacitors (C1-C6). This substitution eliminates the need for magnetic components while achieving the same loop current prevention function through electronic switching and voltage control
2Reliability
If a transformer is used to prevent loop current flow, then loop current is prevented, but device complexity increases
Solution Approach 1:
The transformer is completely extracted from the system architecture. The invention uses a direct AC-to-DC conversion approach with a converter circuit that inherently prevents loop current through controlled switching, simplifying the overall device structure while maintaining reliability
Solution Approach 2:
The power conversion function is segmented into distinct functional blocks: AC switches (S1-S3) for input control, a converter section with transistors (Q1-Q6) for voltage conversion, and capacitors (C1-C6) for voltage regulation. This segmentation allows each component to perform its specific function efficiently without requiring a bulky transformer
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 apparatus effectively prevents loop current flow through the AC power supply, rectifier, and converter, reducing costs by eliminating the need for a transformer while maintaining operational efficiency.
Implementation Method 1
a rectifier that rectifies the first to third AC voltages and outputs a fourth DC voltage
Implementation Method 2
a first capacitor connected between the first and second output nodes; a second capacitor connected between the second and third output nodes
Data Source
AI summary
A controller (5) of an uninterruptible power supply apparatus includes: first to sixth comparator circuits (22a to 22f) respectively provided corresponding to first to sixth IGBTs (Q1 to Q6) and outputting, based on a comparison result of the magnitude of three-phase AC voltages, signals (A1 to A6) indicating that a corresponding IGBT is to be turned on; and a control unit (23) that, when a voltage between terminals (VD1 or VD2) of a first or second capacitor (C11 or C12) is higher than a target voltage (VDT), turns on and off each of the first to sixth IGBTs based on signals output from the first to sixth comparator circuits to decrease the voltage between terminals of the first or second capacitor.