Auxiliary Coil Rectifier Layout for Accurate AC Voltage Detection
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Solution Overview
Problem
Conventional methods for detecting AC voltage in switching power supplies face errors due to noise components generated during switching operations, and using diodes with longer reverse recovery times to mitigate this issue increases power loss.
Innovation Solution
A power supply apparatus with two rectifying/smoothing circuits in parallel, one with a diode having better responsiveness than the other, to detect voltage induced in the auxiliary coil, allowing for accurate voltage detection without significant power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diode with longer reverse recovery time is used to remove noise component, then voltage detection accuracy is improved, but power loss in the diode increases
Solution Approach 1:
The patent divides the single rectifying circuit into two separate rectifying circuits (first and second rectifying circuits) with different diode characteristics. The first rectifying circuit uses a diode with longer reverse recovery time to filter noise, while the second uses a diode with better responsiveness for accurate voltage detection. This segmentation allows each circuit to specialize in one function, resolving the contradiction between noise filtering and detection accuracy.
Solution Approach 2:
The patent applies different diode characteristics to different parts of the system based on local requirements. The first rectifying circuit is designed with a diode having longer reverse recovery time specifically for noise filtering applications, while the second rectifying circuit uses a diode with better responsiveness for voltage detection applications. This local quality approach ensures each component has optimal properties for its specific function.
2Measurement precision
If a diode with much longer reverse recovery time than general rectifying diode is used, then noise component is removed, but sufficient effect cannot always be obtained depending on voltage value and frequency of noise component
Solution Approach 1:
The patent segments the noise filtering function and voltage detection function into separate circuits. The first rectifying circuit with longer reverse recovery time diode handles noise filtering for specific voltage and frequency ranges, while the second rectifying circuit handles voltage detection. This segmentation allows the system to maintain effectiveness across varying noise conditions without requiring a single diode to perform all functions.
Solution Approach 2:
The first rectifying circuit acts as an intermediary between the noisy auxiliary coil voltage and the voltage detection circuit. By placing the first rectifying circuit with noise-filtering diode in between, it preprocesses the voltage signal to remove noise components before the second rectifying circuit performs accurate voltage detection, thereby improving overall system adaptability.
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
The solution improves voltage detection accuracy by absorbing noise components, reducing errors, and minimizing power loss, enabling more precise control of the switching power supply.
Implementation Method 1
a voltage of an AC power supply (hereafter referred to as an AC voltage) may be detected in order to control an output voltage and to protect the switching power supply itself. In order to detect the AC voltage, there is a method in which a voltage proportional to an AC voltage induced in an auxiliary coil provided in a transformer is rectified and smoothed to detect the AC voltage.
Implementation Method 2
a first rectifying/smoothing circuit including a first diode and a first capacitor and configured to rectify and smooth a voltage induced in the auxiliary coil
Implementation Method 3
a first rectifying/smoothing circuit including a first diode and a first capacitor and configured to rectify and smooth a voltage induced in the auxiliary coil
Data Source
AI summary
A power supply apparatus includes a transformer including a primary coil, a secondary coil, and an auxiliary coil; a switching element connected in series to the primary coil; a first rectifying/smoothing circuit including a first diode and a first capacitor and configured to rectify and smooth a voltage induced in the auxiliary coil; a second rectifying/smoothing circuit including a second diode and a second capacitor, connected in parallel with the first rectifying/smoothing circuit, and configured to rectify and smooth the voltage induced in the auxiliary coil; and a controller configured to control the switching element. The controller is configured to detect the voltage induced in the auxiliary coil based on an output voltage of the first rectifying/smoothing circuit. A responsiveness of the second diode is better than a responsiveness of the first diode.