Switching Converter Dual-Loop Control for Light-Load Efficiency
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Solution Overview
Problem
Conventional switching converters experience reduced conversion efficiency due to high power consumption in light-load conditions, particularly when operating in discontinuous conduction mode with constant ON time, as the error amplifier, comparator, and feedback circuit remain active, leading to inefficiency.
Innovation Solution
The switching converter employs a dual-loop control system with a first loop controlling switches via peak current mode and a second loop controlling switches with a switching period, entering a first control mode in light-load conditions to reduce power consumption by turning off sub-circuits of the second loop, and transitioning to a light-load constant ON mode or extended conduction mode for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional switching converter operates in discontinuous conduction mode during light-load conditions, then the converter can maintain basic power conversion function, but power consumption increases and conversion efficiency decreases
Solution Approach 1:
The patent implements dynamic control mode switching between first control mode (peak current mode) and second control mode (conventional mode) based on load conditions. When operating in discontinuous conduction mode, the system dynamically turns off power supplies for sub-circuits in the second loop control circuit, adapting the power consumption level to match the light-load operating condition and thereby reducing overall power consumption while maintaining conversion efficiency
Solution Approach 2:
The patent changes the operational parameters of the control circuits by turning off power supplies to specific sub-circuits (error amplifier, comparator, feedback circuit) when in light-load discontinuous conduction mode. This parameter change from full-power operation to reduced-power operation directly addresses the contradiction by lowering power consumption without sacrificing the essential power conversion function
2Adaptability or versatility
If conventional switching converter enters discontinuous conduction mode during light-load conditions, then the converter can adapt to light load, but power-hungry sub-circuits remain active causing lower efficiency
Solution Approach 1:
The patent segments the second loop control circuit into multiple sub-circuits (error amplifier, comparator, feedback circuit) that can be independently controlled. By selectively turning off power supplies to these individual sub-circuits during light-load discontinuous conduction mode while keeping the essential power conversion function active, the system achieves both light-load adaptability and improved conversion efficiency through selective power management
Data Source
AI summary
A switching converter includes: a power stage circuit which includes at least one switch to switch an inductor to convert an input power to an output power; a first loop control circuit configured to switch the at least one switch by a peak current mode according to a first feedback signal related to the output power and an inductor current of the inductor in a first control mode; and a second loop control circuit configured to control the at least one switch to switch with a switching period according to a second feedback signal in a second control mode. If the power stage circuit operates in DCM during consecutively more than a predetermined number of the switching periods, the switching converter enters the first control mode. A portion of sub-circuits of the second loop control circuit are turned off to reduce power consumption in the first control mode.