Air Conditioner Control Circuit Using Transformer-Isolated AC Signaling
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Solution Overview
Problem
In air conditioners that transmit information using the voltage amplitude of a communication line without a photocoupler, communication is prone to noise and potential offset issues due to lack of electrical insulation from AC power supply and other components, and the use of half-wave rectified DC can be inefficient.
Innovation Solution
A device with a first transformer to output AC voltage, a second transformer, a full-wave rectifier, and a processor to control the air conditioner, where the full-wave rectifier is connected to the secondary side of the second transformer, allowing for accurate information transmission by using the amplitude of AC voltage on a signal line to indicate the state of a switch, thus avoiding potential offset and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If information is transmitted using the voltage amplitude of a communication line without a photocoupler, then communication cost is reduced, but communication reliability deteriorates due to noise and potential offset
Solution Approach 1:
The patent introduces a transformer as an intermediary device between the communication line and the control circuit. The transformer provides electrical insulation while allowing signal transmission through magnetic coupling, thus eliminating direct electrical connection that causes noise and potential offset issues. This mediator enables reliable communication without requiring expensive photocouplers.
Solution Approach 2:
The patent replaces the electrical field-based communication (prone to noise) with a magnetic field-based transmission system using a transformer. By substituting the direct electrical connection with magnetic induction, the system achieves noise immunity and potential isolation similar to photocoupler-based systems but at lower cost.
2Use of energy by moving object
If a full-wave rectifier is connected to the same AC power supply as the destination device, then power efficiency is improved, but communication is negatively affected due to floating output
Solution Approach 1:
The patent divides the power supply system into separate segments: one transformer dedicated to power supply and another transformer dedicated to communication. This segmentation allows the full-wave rectifier to be connected to one transformer without affecting the communication quality on the other transformer, thus achieving both power efficiency and communication reliability.
Solution Approach 2:
The patent uses a second transformer as an intermediary between the full-wave rectifier output and the communication line. This transformer isolates the floating output of the rectifier from the communication circuit, preventing negative effects on communication while still allowing the system to benefit from full-wave rectification efficiency.
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 enables more accurate and efficient information transmission by isolating the communication line from AC power supply noise and utilizing full-wave rectification to improve DC output, reducing potential offset and enhancing communication reliability.
Implementation Method 1
a first transformer configured to output an alternating current (AC) voltage different from an input voltage; a second transformer configured to output an AC voltage different from an input voltage
Implementation Method 2
a full-wave rectifier connected to a secondary side of the second transformer
Data Source
AI summary
A device for controlling an air conditioner has a remote controller which receives an alternating current voltage from a secondary side of a first transformer, a full-wave rectifier connected to a secondary side of a second transformer, and a processor which receives a current rectified by the full-wave rectifier. One of output nodes of the full-wave rectifier is connected to one terminal of the secondary side of the first transformer. The remote controller has a switch connected to the secondary side of the first transformer, and transmits information that indicates a state of the switch to the processor as the amplitude of an AC voltage on a signal line connecting the remote controller and the processor together.