Two-Wire Irrigation Control Using Alternating DC Signals
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Solution Overview
Problem
Existing two-wire irrigation control systems do not fully utilize power bandwidth, leading to reduced power transmission efficiency and increased risk of corrosion due to sinusoidal voltage signals, and they fail to effectively manage communication and power distribution between controllers and irrigation units.
Innovation Solution
A two-wire controlling and monitoring system using alternating DC voltage signals with inverted polarity to improve power transmission efficiency, minimize corrosion risk, and enable two-way communication by modulating pulse widths for data transmission, while allowing for the use of both new and old irrigation control units with a new controller/power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sinusoidal AC voltage signals are used for power transmission, then the system can operate with standard AC power sources, but the power bandwidth is reduced to about 50% of DC systems and power transmission efficiency is reduced
Solution Approach 1:
The patent changes the voltage signal parameter from sinusoidal AC to alternating DC with inverted polarity. This parameter change enables the system to achieve maximum power bandwidth comparable to DC systems while still using AC power sources, resolving the contradiction between power transmission efficiency and power source compatibility
Solution Approach 2:
The patent applies inverted polarity alternating DC voltage signals where the polarity is reversed during different time periods. This inversion technique allows the system to transmit power more efficiently by utilizing both positive and negative voltage cycles, achieving near-100% power bandwidth utilization while maintaining compatibility with AC power sources
2Use of energy by moving object
If pure DC voltage is used for power transmission, then maximum power bandwidth is achieved, but harmful corrosion occurs on the cable due to leakage currents
Solution Approach 1:
The patent employs periodic alternation of voltage polarity instead of continuous DC. By periodically inverting the polarity of the DC voltage signals, the system maintains high power bandwidth utilization while preventing cumulative corrosion through balanced electrochemical conditions during each voltage cycle
Solution Approach 2:
The system preemptively counteracts corrosion by alternating the voltage polarity before harmful corrosion can occur. The periodic inversion creates balanced electrochemical conditions that prevent the accumulation of corrosive effects, addressing the corrosion problem before it manifests
3Loss of information
If power signals are clipped for data transmission, then two-way communication is enabled, but power transmission to remotely located units is significantly reduced
Solution Approach 1:
The patent makes the voltage signal universal by enabling it to serve both power transmission and data communication functions simultaneously. The alternating DC voltage signal with inverted polarity carries power during voltage transitions and encodes data through pulse width modulation, eliminating the need to clip power signals for communication
Solution Approach 2:
The patent merges power transmission and data communication into a single integrated signal system. By encoding data through pulse width variations of the alternating DC voltage signal, the system combines both functions in one signal, avoiding power loss while enabling two-way communication
4Use of energy by moving object
If thicker cables are used to increase power bandwidth, then maximum power delivery is achieved, but system complexity and installation difficulty increase
Solution Approach 1:
The patent changes the electrical parameters of the power transmission system by using alternating DC voltage with inverted polarity instead of sinusoidal AC. This parameter change enables efficient power delivery through existing cable infrastructure without requiring thicker cables, reducing system complexity while maintaining high power bandwidth
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 system achieves improved power transmission efficiency, reduces corrosion risks, and enables efficient communication and monitoring of irrigation parameters, allowing for seamless integration of both new and old units, thereby optimizing irrigation control and monitoring.
Implementation Method 1
supplying power by applying a first alternating DC voltage signal defining a voltage maximum having a first pulse width and defining a voltage minimum having a second pulse width to one of the pair of control and power outputs, simultaneously applying a second alternating DC voltage signal similarly shaped but of inverted polarity
Implementation Method 2
The signaling on the cable is made by changing the frequency of the alternation of the DC. The alternations have a minimum influence on the total power bandwidth.
Data Source
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AI summary
The present invention relates to a method and a system for providing watering or non-watering of an area of soil through controllable irrigation valves (42). Line decoders (44) each connected to a specific irrigation valve provide valve control signals and can communicate with a controller and power supply (30). The irrigation valves (42) comprise a solenoid having a core operable between two positions. The method comprises measuring a self-inductance value and a resistance value of the solenoid. The self-inductance value and the resistance value are transmitted to the controller and power supply (30) or, alternatively, the self-inductance value and the resistance value and signals in the controller and power supply (30) are monitored in case any of the values are outside a predetermined range.