SMPS Burst Mode Control Circuit for Efficiency
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Solution Overview
Problem
Switching mode power supplies (SMPSs) face efficiency issues when load decreases, as power losses increase due to constant switching operations, leading to reduced efficiency in low power modes.
Innovation Solution
A control circuit that receives feedback signals to exit burst mode and enter normal mode based on specific threshold values, adjusting switching operations to maintain efficiency by transitioning from burst mode to normal mode when the feedback signal exceeds certain threshold values, allowing for flexible energy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If constant switching operations are performed in low power modes, then power delivery is maintained, but power losses increase due to constant switching
Solution Approach 1:
The patent implements burst mode operation where the switching transistor operates in periodic bursts rather than continuously. The control circuit monitors feedback signals and switches between normal mode (continuous switching) and burst mode (periodic switching with idle periods). This periodic action reduces switching losses during low power demand while maintaining the ability to deliver power when needed, directly resolving the contradiction between maintaining power delivery and reducing power losses.
2Loss of energy
If burst mode is used to reduce switching losses, then energy efficiency improves, but voltage stability may deteriorate during load changes
Solution Approach 1:
The patent employs a feedback mechanism where the control circuit continuously monitors the feedback signal from the power output. When the feedback signal exceeds the second threshold value for at least a first amount of time and exceeds the third threshold value, the control circuit exits burst mode and enters normal mode. This feedback-based dynamic adjustment ensures voltage stability during load changes while maintaining energy efficiency during normal operation, resolving the contradiction between reducing switching losses and maintaining voltage stability.
Solution Approach 2:
The control circuit dynamically adjusts the switching mode based on real-time feedback conditions. The system transitions between burst mode and normal mode depending on load requirements, making the power supply adaptive rather than static. This dynamic operation allows the system to optimize between efficiency and stability based on actual operating conditions, resolving the contradiction between energy efficiency and voltage stability.
3Measurement precision
If multiple threshold values are used for mode transition, then control precision improves, but device complexity increases
Solution Approach 1:
The patent uses multiple threshold values (first, second, and third threshold values) for the feedback signal to control mode transitions. The third threshold value is larger than the second threshold value, and the first threshold value is larger than the third threshold value. This multi-threshold parameter approach provides precise control over when to enter and exit burst mode, enabling accurate response to different load conditions while keeping the control logic relatively simple through direct threshold comparisons.
Data Source
AI summary
A method of operating a power supply having a transformer, a transistor controlling the current through a primary side of the transformer, and a control unit for controlling the switching of the transistor to generate current pulses in the transformer, is suggested, the method comprising receiving a feedback signal, and exiting a burst mode and entering a normal mode based on the feedback signal in case the feedback signal exceeds a first threshold value or in case the feedback signal exceeds a second threshold value for at least a first amount of time and in case the feedback signal exceeds a third threshold value, wherein the third threshold value is larger than the second threshold value and the first threshold value is larger than the third threshold value.