Deadband DC Converter for Arc Fault Safety
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Solution Overview
Problem
Direct Current (DC) electric transmission and distribution systems are prone to arc faults, requiring expensive protection equipment and inefficient conversion to Alternating Current (AC) for safe distribution, which increases costs and reduces efficiency.
Innovation Solution
A photovoltaic power system that converts DC power into a deadband DC signal with recurring zero-voltage periods, allowing standard AC-rated circuit breakers to safely interrupt arcs and reducing the need for expensive DC-rated equipment by mimicking AC waveform characteristics without full inversion to AC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If DC power is transmitted directly without conversion, then transmission efficiency is improved, but arc fault safety deteriorates requiring expensive DC-rated circuit breakers
Solution Approach 1:
The patent applies periodic action by converting DC power into a modified waveform that includes periodic zero-voltage intervals through controlled rectification and pulsing. This periodic zero-voltage action allows arcs to extinguish naturally during each cycle, providing inherent safety without requiring expensive DC-rated circuit breakers, while maintaining mostly-DC transmission for efficiency.
2Reliability
If DC power is converted to AC using an inverter, then arc fault safety is improved, but system cost and efficiency deteriorate
Solution Approach 1:
The patent extracts only the essential safety feature of AC waveforms—the periodic zero-voltage crossings—while retaining the DC transmission benefits. Instead of full AC conversion, the system creates a hybrid waveform that has AC-like zero-crossings for safety but maintains DC characteristics for efficient transmission, eliminating the need for expensive inverters and DC-rated breakers.
Solution Approach 2:
The patent copies the critical safety characteristic of AC waveforms (periodic zero-voltage points) and applies it to a DC transmission system. By creating artificial zero-crossings in an otherwise DC system, the patent replicates the arc-extinguishing property of AC without requiring full AC conversion, thereby reducing system complexity and cost.
3Device complexity
If standard AC-rated circuit breakers are used in DC systems, then device cost is reduced, but arc interruption capability deteriorates
Solution Approach 1:
The patent creates periodic zero-voltage intervals in the DC transmission waveform, which provides natural arc extinction points that enable standard AC-rated circuit breakers to function effectively. The periodic modulation ensures that when faults occur, arcs are naturally extinguished during zero-voltage periods, allowing inexpensive AC breakers to provide adequate protection.
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
Enables cost-effective, efficient, and reliable DC power distribution using standard AC-rated equipment, reducing the need for expensive DC-rated circuit breakers and maintaining safety by extinguishing arcs during zero-voltage periods.
Implementation Method 1
the deadband DC signal comprises a rectified sine waveform having reoccurring deadband periods of zero-voltage
Implementation Method 2
the DC-DC power converters each include a pair of switching transistors configured for converting the DC power signal into the deadband DC signal
Implementation Method 3
an electric network interface connected to the plurality of DC-DC power converters and configured for converting a deadband DC signal received from the plurality of DC-DC power converters into an AC power signal
Data Source
AI summary
A photovoltaic power system for supplying power to an electric grid is provided, in which a plurality of photovoltaic panels are each configured for generating a DC power signal. A plurality of DC-DC power converters connected to the photovoltaic panels are provided for converting the DC power signal into a deadband DC signal having a rectified sine waveform with reoccurring deadband periods, which reduces the risk of arcing during power transmission. An electric network interface is used to convert the deadband DC signal received from the plurality of DC-DC power converters into an AC power signal.