AC-DC Power Converter Primary Voltage Sensing via Knee Tracking Logic
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Solution Overview
Problem
Switch mode power converters face challenges in accurately estimating and regulating output voltage, especially under varying load conditions, due to limitations in detecting the knee point of the voltage waveform and adjusting reference voltages rapidly enough to maintain precise feedback regulation.
Innovation Solution
The method involves primary side sensing of the voltage waveform, detecting gaps between voltage references to compute tracking errors, and adjusting reference voltages using knee tracking logic, with additional secondary reference voltages to enhance dynamic range and tracking speed, allowing for effective output voltage regulation even under rapidly changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single reference voltage is used for output voltage regulation, then device complexity is reduced, but measurement precision and tracking speed deteriorate under varying load conditions
Solution Approach 1:
The single reference voltage is segmented into multiple reference voltages (first reference voltage, second reference voltage, third reference voltage) with different offset values. Each reference voltage is used for detecting different portions of the voltage waveform, enabling more precise measurement of the knee point position under varying load conditions.
Solution Approach 2:
The patent adds a voltage offset dimension to the reference voltage structure. By introducing multiple reference voltages at different offset levels relative to the primary reference voltage, the system gains an additional dimension for voltage measurement, improving the ability to accurately track the knee point across different operating conditions.
2Stability of the object's composition
If reference voltage adjustment is slowed down to maintain stability, then system stability is improved, but tracking speed and response to load changes deteriorate
Solution Approach 1:
The system dynamically selects which gap measurement to use (first gap or second gap) based on current operating conditions. The knee tracking logic adapts its behavior by choosing different reference voltage combinations, enabling the system to respond quickly to load changes while maintaining stability during normal operation.
Solution Approach 2:
The patent changes the parameter of reference voltage offset values based on operating conditions. By adjusting which reference voltages are used and their relative offsets, the system can optimize both stability and tracking speed for different load conditions without requiring a single fixed reference voltage configuration.
3Measurement precision
If knee point detection accuracy is improved by using multiple reference voltages, then measurement precision is improved, but device complexity and comparator requirements increase
Solution Approach 1:
The multiple reference voltages and comparators serve multiple functions: they detect the knee point position, determine waveform characteristics, and provide feedback for voltage regulation. This multi-functionality justifies the increased device complexity by eliminating the need for separate detection circuits.
Solution Approach 2:
The system uses the gap measurements from multiple comparator operations to generate feedback signals that drive the voltage regulation process. The knee tracking logic uses the detected gaps to adjust the output voltage, creating a closed-loop feedback system that improves measurement precision through active utilization of the multiple reference voltages.
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 approach enables accurate and rapid adjustment of reference voltages to maintain stable output voltage regulation, improving tracking efficacy and handling varying load conditions by utilizing multiple reference voltages and enhanced comparator logic.
Implementation Method 1
a first comparator to generate a first comparison signal based on a comparison between a sensed voltage waveform and a first reference voltage
Data Source
AI summary
A method for estimating an output voltage of a power converter comprises sensing a voltage waveform representative of the output voltage; and detecting a first gap and a second gap. The first gap is between a time when the sensed voltage waveform crosses a first voltage reference and a time when the sensed voltage waveform crosses a second voltage reference at a voltage offset below the first voltage reference. The second gap is between a time when the sensed voltage waveform crosses a third voltage reference and a time when the sensed voltage waveform crosses the second voltage reference, the third voltage referenced at a predetermined voltage above the second voltage reference. Responsive to the first gap exceeding a threshold, a tracking error is computed based on the first gap; and responsive to the first gap not exceeding the threshold, the tracking error is computed based on the second gap.