Switching Power Supply Correction Circuit Light Load Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switching power supply devices face challenges in reducing power consumption during light loading or no loading, particularly due to inefficiencies in current detection and correction circuits, which lead to increased power losses and difficulties in adjusting overcurrent detection across varying input voltages.
Innovation Solution
A switching power supply device with a correction circuit that applies a positive offset voltage to the current detection signal only during on intervals of the switching element, using a resistor or a combination of resistor and capacitor, to reduce power losses and adjust switching frequency without affecting overcurrent limits or other characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a correction circuit is added to adjust switching frequency during light loading, then power consumption during light loading is reduced, but power losses in the correction circuit increase
Solution Approach 1:
The correction circuit is designed to operate only during the on intervals of the switching element through periodic activation synchronized with the switching cycle. This is achieved by connecting the correction circuit between the output terminal and signal input terminal for current detection, where it receives periodic drive signals that enable it to apply offset voltage only during specific phases of the switching cycle, thereby reducing continuous power consumption while maintaining frequency adjustment capability during light loading conditions
Solution Approach 2:
The correction circuit dynamically adjusts its operation based on the switching element's state by receiving drive signals that correspond to the on intervals. The circuit's activation is made dynamic through time-dependent control, where the offset voltage application is synchronized with the switching cycle, allowing the circuit to be active only when needed for frequency adjustment during light loading rather than operating continuously
2Loss of energy
If switching frequency is lowered during light loading, then switching losses are reduced, but overcurrent detection accuracy deteriorates
Solution Approach 1:
The correction circuit acts as an intermediary between the current detection means and the switching power supply control means by injecting an offset voltage signal into the current detection signal path. This intermediary correction signal compensates for the frequency-dependent detection errors, allowing accurate overcurrent detection to be maintained across varying switching frequencies including the reduced frequencies used during light loading conditions
Solution Approach 2:
The correction circuit changes the voltage parameter of the current detection signal by adding an offset voltage that is proportional to the switching frequency. This parameter adjustment compensates for the detection accuracy deterioration that occurs at lower switching frequencies, effectively maintaining consistent overcurrent detection accuracy across the full operating range including light loading conditions
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 reduces power losses by limiting current flow to only during control signal on intervals, allowing for efficient frequency adjustment during light loading without impacting overcurrent detection, thus enhancing energy efficiency and reducing standby power consumption.
Implementation Method 1
a correction circuit, which acts only during on intervals of the switching element, and applies a positive offset voltage to the voltage signal output from the current detection means
Data Source
AI summary
A switching power supply device has lower correction circuit losses, and enables adjustments without affecting overcurrent limiting or other characteristics. An integrated circuit IC for power supply control generates a switching signal based on a feedback signal from a feedback circuit and a voltage signal from a current detection input terminal, and outputs the switching signal from an output terminal to a switching element. A voltage controlled oscillator is provided which, when the load is judged to be light based on the magnitude of the feedback signal, lowers the switching frequency. The correction circuit is connected between the output terminal of the integrated circuit and the signal input terminal for current detection, acts only when the switching element is on, and has the function of further lowering the switching frequency set in the integrated circuit.