Control circuit and switching converter
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Solution Overview
Problem
Switching power supplies face challenges in maintaining output voltage accuracy under light load conditions due to limitations in the variation range of correction signals, leading to reduced system accuracy and dynamic performance issues.
Innovation Solution
A control circuit that superimposes a ripple signal with a variation range between zero and a preset value on the feedback voltage, eliminating the need for a correction signal and utilizing a single voltage loop for rapid load response, thereby enhancing output voltage accuracy and dynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a correction signal is used to eliminate DC offset voltage caused by ripple signal injection, then output voltage accuracy is improved, but device complexity increases due to the need for correction circuits and dual voltage loops
Solution Approach 1:
The patent extracts and eliminates the correction signal and correction circuit from the control system. By using a single voltage loop without DC offset correction, the patent removes the harmful factor (circuit complexity) while maintaining output voltage accuracy through alternative means (single loop design with ripple signal injection at the comparator input).
Solution Approach 2:
The patent merges the voltage regulation function into a single voltage loop, combining the ripple signal injection and voltage regulation into one integrated control path. This eliminates the need for separate correction circuits and dual loops, thereby reducing device complexity while maintaining control precision.
2Measurement precision
If a correction circuit is implemented to eliminate DC offset, then output voltage accuracy is improved, but the response speed to load changes deteriorates due to the dual voltage loop structure
Solution Approach 1:
The patent extracts and removes the correction circuit and DC offset elimination mechanism from the system. By using a single voltage loop without these correction elements, the patent eliminates the bottleneck in the control path, thereby improving the response speed to load changes while maintaining voltage accuracy through the simplified control architecture.
Solution Approach 2:
Instead of using a dual-loop structure with correction circuits to achieve voltage accuracy, the patent inverts the approach by using a single loop with ripple signal injection directly at the comparator input. This inverted approach achieves both accuracy and fast response by eliminating the hierarchical loop structure that slows down the response.
3Speed
If ripple signal injection is used for constant on-time control, then dynamic performance is improved, but DC offset voltage causes output voltage inaccuracy
Solution Approach 1:
The patent accepts the presence of small DC offset voltage as a tolerable imperfection that does not significantly affect overall system performance. By focusing on the beneficial dynamic performance improvement from ripple signal injection and accepting minor accuracy trade-offs, the patent achieves a practical solution that prioritizes dynamic response while maintaining sufficient voltage accuracy through the single loop design.
Data Source
AI summary
A control circuit for a switching converter, can include: a ripple signal generation circuit configured to generate a ripple signal with a same frequency and phase as an inductor current of the switching converter, where the ripple signal changes between zero and a preset value; a superimposing circuit configured to superimpose the ripple signal on a feedback signal representing an output voltage of the switching converter, in order to generate a loop control signal; and a switching control signal generation circuit configured to generate switching control signals according to the loop control signal and a reference signal, in order to control a switching state of a power stage circuit in the switching converter.