AC Power Frequency Determination Using DC Voltage Ripple Analysis
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Solution Overview
Problem
Existing frequency detection circuits for AC power in devices like air conditioning consume power even in standby mode due to voltage-dividing resistors, requiring complex processing to determine frequency during power supply, and often necessitate a separate frequency detection circuit.
Innovation Solution
A power supply frequency determination device that uses a voltage detection means to convert AC power to DC, with a voltage determination means checking if the DC voltage falls within a predetermined reference range at time intervals corresponding to assumed AC power frequencies, and a frequency determination means validating the frequency based on the number of times the DC voltage enters this range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a frequency detection circuit with voltage-dividing resistor is used to determine AC power frequency, then frequency detection capability is achieved, but power consumption increases even in standby state
Solution Approach 1:
The patent extracts the frequency detection function from a separate dedicated circuit and integrates it into the existing converter control system. By using the converter's existing voltage detection capabilities to monitor DC voltage ripple characteristics, the system eliminates the need for a separate frequency detection circuit with voltage-dividing resistors, thereby achieving frequency detection without the associated standby power consumption.
Solution Approach 2:
The patent makes the converter's voltage detection system multi-functional by using it for both its original purpose (voltage regulation) and frequency detection. The same voltage detection mechanism that monitors DC bus voltage is also used to analyze ripple characteristics for frequency determination, eliminating the need for dedicated frequency detection hardware and reducing overall system power consumption.
2Measurement precision
If frequency detection is performed simultaneously with power supply to ensure accurate frequency determination, then detection accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent performs frequency detection during the power supply initialization phase, before the converter begins normal operation. By detecting the AC power frequency during this preliminary stage using the initial DC voltage ripple characteristics, the system establishes the frequency information needed for subsequent PAM control without requiring complex real-time frequency analysis during operation.
Solution Approach 2:
The patent uses the existing DC voltage ripple waveform as a copy or indicator of the AC power frequency characteristics. Instead of directly analyzing the AC voltage waveform or using complex frequency analysis algorithms, the system infers AC frequency from the ripple frequency in the DC voltage, which is a simplified representation that requires less processing complexity.
3Reliability
If a separate frequency detection circuit is provided to accurately detect AC power frequency, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the frequency detection function with the existing converter control circuitry. By combining multiple functions (voltage regulation and frequency detection) into a single integrated system, the patent eliminates the need for separate frequency detection circuits while maintaining detection reliability through the use of the converter's inherent voltage sensing capabilities.
Solution Approach 2:
The converter system performs frequency detection for itself using its own voltage detection mechanisms. The converter's control system analyzes its own DC voltage ripple characteristics to determine the AC power frequency, eliminating the need for external or separate frequency detection equipment and simplifying the overall system architecture.
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 accurate determination of AC power frequency without a separate frequency detection circuit, reducing standby power consumption and simplifying the processing involved in frequency detection.
Implementation Method 1
a DC voltage converted from AC power by a converter
Data Source
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AI summary
Abstract: The purpose of the present invention is to determine the frequency of AC power, without providing a separate frequency detection section. An air conditioning control device (26) is provided with a voltage detection unit (24) for detecting DC voltage which has been converted from DC power by a converter (20). The air conditioning control device (26) then determines whether the detected DC voltage has entered a prescribed reference voltage range, doing so in a time interval dependent on the assumed frequency of the AC power. The correctness or incorrectness of the assumed frequency is determined on the basis of the number of times that the DC voltage was determined to have entered the reference voltage range, within a time range dependent on the assumed frequency.