Switching Power Circuit Overcurrent Control for Stable Output Voltage
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Solution Overview
Problem
Conventional switching power circuits experience unstable output voltages during overcurrent protection, leading to unstable device operations. There is a need for a switching power circuit that can maintain stable output voltage during overcurrent protection and quickly return to normal operation when the overload state is released.
Innovation Solution
The proposed switching power circuit compares a reference voltage with a feedback voltage and adjusts the output voltage by decreasing the reference voltage when the output current exceeds a predetermined set current. This circuit includes an overcurrent sensing device and an overcurrent protection circuit that uses a phase compensation digital filter and a D/A converter to generate a protection voltage that adjusts the reference voltage accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage feedback control is stopped at the time of overcurrent protection, then overcurrent is protected, but output voltage becomes unstable
Solution Approach 1:
The feedback control is segmented into two independent paths: voltage feedback control (stopped during overcurrent protection) and current feedback control (activated during overcurrent protection). This segmentation allows the system to protect against overcurrent while maintaining output voltage stability through the current feedback path.
Solution Approach 2:
A current feedback control circuit acts as an intermediary mechanism that takes over control when voltage feedback control is stopped. The current feedback control uses a different reference voltage (lower than the normal reference voltage) to regulate output current, thereby maintaining output voltage stability during overcurrent protection.
2Reliability
If voltage feedback control is stopped during overcurrent protection, then overcurrent protection is achieved, but recovery to normal state is delayed
Solution Approach 1:
The feedback control mode is dynamically switched based on operating conditions. The system transitions from voltage feedback control to current feedback control during overcurrent protection, and automatically returns to voltage feedback control when protection is no longer needed. This dynamic switching enables rapid recovery to normal state without manual intervention.
Solution Approach 2:
The system continuously monitors output current and automatically switches between control modes based on feedback. When output current exceeds the threshold, current feedback control is activated; when it returns to normal, voltage feedback control resumes. This feedback mechanism ensures rapid and automatic recovery to normal operation.
3Stability of the object's composition
If current feedback control is introduced for overcurrent protection, then output voltage stability is maintained, but device complexity increases
Solution Approach 1:
The current feedback control circuit serves multiple functions: it acts as an overcurrent protection mechanism, maintains output voltage stability during protection, and enables automatic recovery to normal operation. By combining these functions into a single control path, the system avoids the need for separate protection circuits, thereby limiting the increase in device complexity.
Data Source
AI summary
According to one embodiment, a switching power circuit compares a reference voltage with a feedback voltage of an output voltage, and controls the output voltage in accordance with the reference voltage, in which in a case where the output current is greater than a predetermined set current, the voltage of the reference voltage is decreased.