Zero-Crossing AC Input Voltage Sensing Without Extra Hardware
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Solution Overview
Problem
Existing systems for determining input voltages in electronic devices require multiple hardware and software components, increasing costs and complexity, especially when dealing with fluctuating voltages in AC systems.
Innovation Solution
A method and system utilizing a zero-crossing detector (ZCD) circuit and microcontroller to measure half-cycle times of AC signals, converting them into square waveforms, and determining input voltage ranges without additional hardware, allowing for efficient voltage sensing across various AC voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple hardware components are used to determine input voltage ranges, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the voltage sensing function from dedicated hardware components and implements it through software-based zero-crossing detection using existing microcontroller resources. This eliminates the need for separate voltage sensing hardware while maintaining measurement capability through timing-based voltage range determination.
Solution Approach 2:
The microcontroller's existing zero-crossing detection circuitry, originally designed for timing purposes, is made multi-functional by using it simultaneously for both timing measurements and voltage range determination. This universal use of existing resources eliminates the need for additional dedicated voltage sensing hardware.
2Measurement precision
If additional hardware is added for voltage sensing, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the requirement for additional voltage sensing hardware by extracting the voltage measurement function and implementing it through software processing of timing data from existing zero-crossing detection circuits, thereby reducing component count and manufacturing cost.
Solution Approach 2:
The patent uses inexpensive, readily available microcontroller units with built-in zero-crossing detection capability, replacing the need for more expensive dedicated voltage sensing hardware. The solution leverages low-cost existing components rather than requiring additional expensive specialized parts.
3Device complexity
If zero-crossing detection is used to measure half-cycle time, then device complexity is reduced, but measurement precision may be affected by voltage fluctuations
Solution Approach 1:
The patent employs feedback by measuring multiple half-cycle times and using the average value to determine voltage range. This feedback approach compensates for individual measurement variations caused by voltage fluctuations, maintaining precision despite using a simplified hardware approach.
Solution Approach 2:
The patent uses periodic measurement of multiple half-cycle times to improve accuracy. By taking multiple periodic measurements and averaging them, the system compensates for transient voltage variations while maintaining the simplicity of the zero-crossing detection method.
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 and efficient voltage sensing in AC systems, reducing the need for extra circuitry and pins, and allowing for adaptive operation across different voltage ranges, including 120 VAC, 277 VAC, and 347 VAC, while preventing overload by generating error values and turning off loads as necessary.
Implementation Method 1
measuring a half-cycle time of an AC signal by using a zero-crossing detector (ZCD) to detect a first edge, being a rising or falling edge, of the AC signal
Implementation Method 2
using a timer to determine a start time... using the timer to determine a stop time and a length of time that lapsed from the start time and the stop time
Data Source
AI summary
Systems and methods are provided for measuring input voltage in an alternating current (AC) system is provided. The method includes measuring a half-cycle time of an AC signal by: detecting, using a zero crossing detector (ZCD), a first edge of the AC signal; in response to detecting the first edge, using a timer to determine a start time; detecting, using the microcontroller, a subsequent edge of the square wave output of ZCD signal; and, in response to detecting the subsequent edge, using the timer to determine a stop time and a length of time that lapsed from the start and stop times. The method further includes determining an overall value that corresponds to at least one length of time, determining, based on the overall value, an input voltage range that corresponds to the overall value, and using the input voltage to cause the AC system to take an action.