Transformerless Power Conversion Neutral Grounding
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Solution Overview
Problem
Traditional power systems require galvanic isolation to connect alternative energy sources like generators to a utility grid, leading to potential ground current loops and safety hazards, and they lack efficient energy conversion and the ability to couple multiple power sources together.
Innovation Solution
A transformerless power system that capacitively couples the neutral output of power sources to a DC bus, eliminating the need for galvanic isolation and allowing direct connection to a utility side neutral, enabling solid grounding without impedance and facilitating the connection of multiple power sources to a common DC bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation is used to connect alternative energy sources to the utility grid, then safety is improved, but ground current loops are created and energy conversion efficiency decreases
Solution Approach 1:
The patent extracts and eliminates the transformer (isolation mechanism) from the power conversion system. By removing the galvanic isolation component, the system achieves direct coupling between the alternative energy source and utility grid, eliminating energy losses associated with transformation while maintaining safety through controlled neutral grounding.
Solution Approach 2:
The patent introduces a neutral grounding switch as an intermediary device that controls the connection between the power source neutral and the utility ground. This mediator enables safe operation by providing a controlled path for fault currents without requiring continuous galvanic isolation, thus improving efficiency while maintaining safety.
2Reliability
If galvanic isolation is used to connect power sources, then safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the transformer and associated isolation mechanisms from the system, significantly reducing device complexity. The neutral grounding switch provides a simpler alternative that maintains safety without the burden of continuous galvanic isolation infrastructure.
3Reliability
If galvanic isolation is used, then safety is improved, but the ability to couple multiple power sources together is reduced
Solution Approach 1:
The patent creates a universal coupling mechanism where multiple alternative energy sources can be connected to a common neutral bus and grounded through the neutral grounding switch. This multi-functional approach allows different power sources (solar, wind, battery) to be interconnected and simultaneously coupled to the utility grid without requiring individual isolation mechanisms for each source.
4Reliability
If intentional impedance is inserted between neutral and ground, then safety is improved, but grounding effectiveness and fault clearing capability decrease
Solution Approach 1:
The patent employs a dynamic neutral grounding switch that can change the grounding state based on system conditions. During normal operation, the switch provides solid grounding for effective fault clearing. When faults are detected or during specific operational modes, the switch can open to provide impedance, thereby maintaining safety while preserving fault clearing capability when needed.
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 solution eliminates ground current loops, enhances energy conversion efficiency, and allows for automatic fault clearing, while enabling the connection of single or split phase power sources to a utility grid without safety hazards, and allows multiple power sources to be coupled together efficiently.
Implementation Method 1
generating first and second rectified outputs from first and second AC power using a rectifier
Implementation Method 2
capacitively coupling the first and second rectified outputs to a neutral
Implementation Method 3
generating first and second AC power from the first and second rectified outputs
Data Source
AI summary
A power system including a rectifier and an inverter. The rectifier has a plurality of phase input terminals and a plurality of rectifier output terminals that provide respective rectified outputs, rectifier circuitry that rectifies the signals on the phase input terminals to generate respective rectified outputs on the rectifier output terminals, a rectifier neutral to receive a power source neutral, and capacitors connected between the rectifier neutral and the rectifier output terminals. The inverter includes a respective plurality of inverter input terminals respectively connected to the rectifier output terminals, a plurality of inverter output terminals, and an inverter neutral. The rectifier neutral and the inverter neutral are coupled by a conductor to form a same neutral.