Switching Power Supply Load Detection Threshold Control
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Solution Overview
Problem
Existing switching power supply devices face challenges in reliably controlling the operation of power factor correction converters due to incorrect detection of load changes when the AC voltage decreases, leading to unintended operation and reduced conversion efficiency.
Innovation Solution
A switching power supply device with a load state detecting circuit that sets a threshold based on the maximum output voltage of the power factor correction converter in an operation-stopped state, preventing false detection of load increases and ensuring reliable operation control even when the AC voltage decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the threshold for detecting load increases is set based on the minimum output voltage of the power factor correction converter, then the detection sensitivity is improved, but false detection of load increases occurs when AC voltage decreases
Solution Approach 1:
The patent changes the reference parameter from minimum output voltage to maximum output voltage of the power factor correction converter. By setting the threshold based on maximum voltage rather than minimum voltage, the system avoids false detection caused by voltage drops during light load conditions, thereby resolving the contradiction between detection sensitivity and reliability.
2Stability of the object's composition
If the power factor correction converter operates continuously, then the output voltage stability is maintained, but conversion efficiency decreases due to unnecessary operation during light load conditions
Solution Approach 1:
The patent implements dynamic control of the power factor correction converter by enabling it to switch between operating and stopped states based on actual load conditions. The load state detecting circuit dynamically adjusts the converter's operation status, allowing it to stop during light load conditions to improve efficiency and restart when load increases, thus resolving the contradiction between continuous operation stability and energy efficiency.
3Device complexity
If the load state detecting circuit uses a fixed threshold, then the circuit complexity is reduced, but the detection accuracy decreases when AC voltage varies
Solution Approach 1:
The patent applies preliminary action by pre-setting the threshold based on the maximum output voltage characteristics of the power factor correction converter. This pre-calculated threshold, derived from the relationship between AC voltage and maximum output voltage, enables accurate load detection across varying AC voltage conditions without requiring complex real-time adjustments, thus resolving the contradiction between circuit simplicity and detection accuracy.
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 effectively prevents mistaken detection of load increases, allowing for accurate control of the power factor correction converter operation, thereby improving conversion efficiency and stability.
Implementation Method 1
a power factor correction converter which obtains a DC voltage by switching an input AC voltage
Implementation Method 2
A control circuit IC2 generates quasi-resonance between leakage inductance of the isolation transformer T and the resonant capacitor C4 by driving the switching element Q2 on/off to thereby generate a predetermined DC output voltage Vo
Implementation Method 3
a rectifier circuit which rectifies AC power fed from a commercial power supply 5
Data Source
AI summary
In some aspects of the invention, a load state detecting circuit is configured so that a threshold voltage for determining the size of a load of a DC-DC converter is set in the load state detecting circuit based on a maximum value of an output voltage of a power factor correction converter in an operation-stopped state of the power factor correction converter, so that the load state detecting circuit outputs an operation-enable signal when a feedback voltage indicating the size of the load of the DC-DC converter exceeds the threshold voltage. Thus, by way of some aspects of the invention, it is possible to provide a switching power supply device which can control enabling and stopping operation of a power factor correction converter reliably in accordance with a load state of a DC-DC converter obtaining a predetermined DC output voltage by switching an output voltage of the correction converter.