Two-Wire Irrigation Control Using Alternating DC Signals
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Solution Overview
Problem
Existing two-wire irrigation control systems face challenges in efficient power transmission and noise sensitivity due to sinusoidal signals, which require conversion to DC for microprocessor electronics, leading to increased costs and power loss, and are prone to corrosion and leak currents.
Innovation Solution
A two-wire controlling and monitoring system using alternating DC voltage signals with inverted polarity for improved power transmission, reducing noise sensitivity and corrosion risk, and incorporating a method to compensate for leak currents, allowing for efficient communication and monitoring of irrigation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sinusoidal AC signals are used for power transmission on two-wire cables, then power can be transmitted to remotely located irrigation valves and decoders, but power loss is significantly reduced and noise sensitivity increases
Solution Approach 1:
The patent changes the signal type from sinusoidal AC to square wave DC, fundamentally altering the electrical parameters to eliminate noise sensitivity while maintaining power transmission capability. This parameter change allows the system to operate without signal clipping while providing inherent noise immunity.
Solution Approach 2:
The patent replaces the traditional AC power transmission mechanism with a DC square wave mechanism, substituting one electrical system for another that better suits the requirements of noise immunity and microprocessor compatibility without requiring AC-to-DC conversion at remote locations.
2Power
If sinusoidal AC signals are used for transmitting power, then power can be delivered to remote devices, but additional AC-to-DC conversion electronics are required at remote locations increasing system cost
Solution Approach 1:
The patent substitutes AC power delivery with DC square wave power delivery, eliminating the need for AC-to-DC conversion electronics at remote locations. The square wave DC signal can be directly rectified and filtered with simple circuitry already present in most microprocessor systems, significantly reducing component costs.
Solution Approach 2:
The patent extracts the AC-to-DC conversion function from the remote location devices and relocates it to the central controller, which generates the square wave DC signal. This extraction eliminates the need for complex power conversion electronics at distributed valve and sensor locations.
3Loss of information
If signal clipping is performed on power lines for communication, then data can be transmitted to remote valves and sensors, but power transmission to these devices is significantly reduced
Solution Approach 1:
The patent merges power transmission and data communication into a unified square wave DC signal protocol. Data is encoded in the transitions and patterns of the square wave itself, allowing simultaneous power delivery and communication without the need for separate clipping operations that would interrupt power flow.
Solution Approach 2:
The patent uses periodic square wave transitions to encode data while maintaining continuous power delivery. The regular periodic nature of the square wave allows for reliable data encoding through edge detection and timing analysis without interrupting the power supply to remote devices.
4Adaptability or versatility
If two-wire cable signalling is implemented for control and monitoring, then remote irrigation control is achieved, but corrosion and leak currents affect system reliability
Solution Approach 1:
The patent changes the electrical signal characteristics to square wave DC, which has different electrochemical properties compared to AC signals. This parameter change reduces the tendency for electrolytic corrosion in the two-wire cable by eliminating the continuous polarity reversal that drives corrosion processes.
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, reduced noise sensitivity, and enhanced corrosion resistance, while minimizing power loss and operational costs, enabling effective monitoring and control of irrigation systems.
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 said pair of control and power outputs, simultaneously applying a second alternating DC voltage signal similarly shaped but of inverted polarity as compared to said first alternating DC voltage signal
Data Source
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Figure 5
AI summary
A two-wire controlling and monitoring system for in particular irrigation of localised areas of soil comprises a water pipeline, a first plurality of controllable irrigation valves, a third plurality of localised irrigation control units each comprising a line decoder. The two-wire controlling and monitoring system further comprises a controller and power supply unit having a set of schedules of instructions and having a pair of control and power outputs supplying power to one of the pair of control and power outputs, and a two-wire cable interconnecting said controller and power supply unit and said third plurality of localised irrigation control units. The controller and power supply unit transmits the schedules of instructions to the third plurality of localised irrigation control units through the two-wire cable and receives the specific irrigation parameters from the third plurality of localised irrigation control units through the two-wire cable.