Power Conversion Device Neutral Conductor Potential Control
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Solution Overview
Problem
Existing AC/DC power conversion devices for single-phase three-wire systems face inefficiencies, size issues, and high costs, particularly in generating and controlling potential at a neutral conductor during power failures.
Innovation Solution
A power conversion device comprising a first and second full bridge circuit, transformers, reactors, and capacitors, with a controller managing switching elements to achieve bidirectional power conversion and maintain voltage balance, allowing for intermediate voltage output at a neutral conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switching circuit is added to generate and control potential at a neutral conductor during power failure, then the AC/DC power conversion device can support autonomous operation, but efficiency decreases, size increases, and cost increases
Solution Approach 1:
The power conversion device uses its own full-bridge circuit components (capacitors, reactors, switching elements) to generate the neutral conductor potential during power failure, without requiring external assistance or additional dedicated circuits. The existing components serve dual purposes: normal power conversion and neutral potential generation
Solution Approach 2:
The full-bridge circuit components are designed to perform multiple functions: during normal operation they enable bidirectional power conversion, and during power failure they generate and control the neutral conductor potential for autonomous operation of single-phase three-wire AC loads
2Reliability
If a switching circuit is added to generate and control potential at a neutral conductor during power failure, then the AC/DC power conversion device can support autonomous operation, but efficiency decreases, size increases, and cost increases
Solution Approach 1:
The power conversion device uses its own full-bridge circuit components (capacitors, reactors, switching elements) to generate the neutral conductor potential during power failure, without requiring external assistance or additional dedicated circuits. The existing components serve dual purposes: normal power conversion and neutral potential generation
Solution Approach 2:
The full-bridge circuit maintains continuous useful action by seamlessly transitioning between normal power conversion mode and neutral potential generation mode, ensuring that the switching elements and reactive components remain actively engaged in productive functions throughout all operating conditions
3Stability of the object's composition
If the power conversion device outputs intermediate voltage at a neutral conductor, then voltage balance is stabilized during unbalanced AC load conditions, but the circuit configuration becomes more complex
Solution Approach 1:
The power conversion device handles unbalanced AC loads by creating an asymmetric neutral point potential through controlled switching, where the neutral conductor potential is adjusted independently from the phase voltages to maintain proper voltage balance despite unequal load conditions
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 solution enhances efficiency, reduces size and cost, and stabilizes voltage balance, ensuring stable AC output even during unbalanced AC load conditions and power failures.
Implementation Method 1
a transformer; a first reactor connected between the first full bridge circuit and the transformer; a second reactor connected between the first full bridge circuit and the transformer; a third reactor connected between the second full bridge circuit and the transformer
Implementation Method 2
a first reactor connected between the first full bridge circuit and the transformer; a second reactor connected between the first full bridge circuit and the transformer; a third reactor connected between the second full bridge circuit and the transformer
Implementation Method 3
a first capacitor circuit that includes a first capacitor and a second capacitor connected in series; The first full bridge circuit is connected in parallel to the first capacitor circuit
Data Source
AI summary
In a power conversion device, a voltage at an input/output terminal of a primary-side circuit is divided by a first capacitor and a second capacitor, and a center tap provided to the primary winding of a transformer is connected to a node between the first capacitor and the second capacitor. With this, an intermediate voltage can be output. Further, transmission power can be controlled under a state where a voltage at the first capacitor and a voltage at the second capacitor are balanced, through adjustment of switching phases of a first full bridge circuit that is the primary-side circuit and a second full bridge circuit that is a secondary-side circuit.