HVAC Controller Multiplexing for AC Input Signal Detection
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Solution Overview
Problem
HVAC controllers face challenges in efficiently detecting alternating current (AC) input signals, as scanning these signals consumes significant bandwidth and requires multiple physical pins, increasing cost and complexity.
Innovation Solution
The implementation of a signal conditioner to convert AC input signals into square wave signals, a multiplexer to select and analyze these signals, and a sample analyzer to derive binary states, allowing for multiplexed input signal detection and reducing the need for multiple pins and scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC input signals are scanned using traditional methods, then the controller can detect binary states, but computational load and bandwidth consumption increase significantly
Solution Approach 1:
The patent replaces the traditional software-based scanning mechanism with a hardware-based signal conditioning circuit that converts AC signals into square wave signals. This substitution eliminates the need for continuous polling and complex computational analysis, as the hardware circuit inherently transforms the signal into a form that can be directly read by the controller, thereby reducing computational load while maintaining detection accuracy.
Solution Approach 2:
The signal conditioning circuit changes the parameter of the AC input signal by converting it from an alternating current waveform into a square wave signal with digital logic voltage levels. This parameter transformation simplifies the detection process, as the square wave signal clearly indicates binary states through its high and low voltage levels, enabling accurate detection with minimal computational resources.
2Reliability
If multiple physical pins are used to detect AC input signals, then signal detection reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent implements a universal signal conditioning circuit that can handle multiple AC input signals through a single pin interface. The circuit is designed to accept multiple inputs and process them through a unified pathway, allowing the controller to detect multiple signals without requiring proportional increases in physical pins, thereby reducing device complexity while maintaining reliable detection.
Solution Approach 2:
The patent merges multiple signal detection functions into a single integrated signal conditioning circuit. By combining the signal conditioning, waveform transformation, and input interface into one unified circuit block, the system achieves reliable multi-signal detection without the need for separate pins for each signal, thus simplifying the overall device architecture.
3Productivity
If AC input signals are converted to square wave signals, then signal detection efficiency improves, but additional hardware components are required
Solution Approach 1:
The patent segments the signal detection function into distinct modular components: a signal conditioning circuit for waveform transformation, a multiplexer for signal selection, and a controller for processing. This segmentation allows each component to perform its specific function efficiently, improving overall detection efficiency while enabling independent optimization and maintenance of each module.
Solution Approach 2:
The signal conditioning circuit acts as an intermediary between the AC input signals and the controller. It mediates the signal transformation process by converting AC waveforms into square waves, thereby bridging the gap between analog input signals and digital processing requirements. This intermediary function improves detection efficiency by providing the controller with pre-processed, easily interpretable signals.
Data Source
AI summary
A heating, ventilation and air conditioning (HVAC) controller, a method of detecting multiplexed input signals and an HVAC system employing the controller or the method. In one embodiment, the HVAC controller includes: (1) a signal conditioner configured to convert received alternating current (AC) input signals into corresponding square wave signals of a digital logic voltage, (2) a multiplexer coupled to the signal conditioner and configured to select one of the square wave signals and (3) a sample analyzer coupled to the multiplexer and configured to evaluate multiple samples of the selected one of the square wave signals to derive a binary state.