Switching Power Supply Reverse Current Detection at Light Load
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Solution Overview
Problem
Existing switching power supply apparatuses face inefficiencies in light-load states due to reverse current flow, which reduces efficiency and increases losses.
Innovation Solution
The implementation of a light-load support circuit with a reverse current detection circuit and an offset correction circuit, which detects the reverse current and adjusts the offset voltage to optimize the switching timing, thereby minimizing inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional switching power supply apparatus operates in light-load states, then the basic switching function is maintained, but reverse current flow occurs which reduces efficiency and increases losses
Solution Approach 1:
The power supply control device dynamically adjusts the offset voltage based on operating conditions (light-load vs. normal load states). The control unit changes the offset voltage value according to the load level, enabling the system to adapt to varying operating conditions and prevent reverse current flow during light-load operation, thereby resolving the efficiency loss problem without compromising basic switching functionality
Solution Approach 2:
The invention changes the offset voltage parameter dynamically based on the operating state. During light-load states, the offset voltage is adjusted to a specific value that prevents reverse current flow, while during normal operation it maintains its standard value. This parameter adjustment directly addresses the energy loss issue by modifying the voltage threshold that controls the switching timing, thereby eliminating the harmful reverse current effect
2Productivity
If the offset voltage is adjusted to suppress reverse current, then efficiency is improved, but the switching timing precision must be maintained
Solution Approach 1:
The control unit continuously monitors the operating state and adjusts the offset voltage accordingly. This feedback mechanism ensures that the offset voltage is only modified when necessary (during light-load states), and is restored to its original value during normal operation, thereby maintaining switching timing precision while improving efficiency during specific operating conditions
Solution Approach 2:
The system dynamically switches between different offset voltage values based on load conditions. The control unit detects the operating state and transitions the offset voltage between two distinct values, ensuring that switching timing precision is maintained during normal operation while efficiency is improved during light-load states through dynamic parameter adjustment
Data Source
AI summary
In a switching power supply apparatus configured to generate an output voltage from an input voltage, the output voltage is obtained by rectifying and smoothing a switch voltage obtained by alternately turned on and off first and second transistors connected in series to each other in accordance with the output voltage. A light-load support circuit includes a reverse current detection circuit that outputs a reverse current detection signal when a magnitude of the switch voltage is lower than an offset voltage during an on period of the second transistor, and an offset correction circuit. In response to the reverse current detection signal, a transition to a specific state occurs, in which the first and second transistors are off. The offset correction circuit corrects the offset voltage on the basis of the switch voltage at a specific timing of being switched to the specific state.