Switch Mode Power Converter Burst Mode Control
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Solution Overview
Problem
Conventional switched mode power converters face challenges in reducing power consumption at no load or low load conditions due to continuous switching, which leads to inefficiencies and increased noise susceptibility of error signals.
Innovation Solution
The implementation of a burst mode control mechanism, where the controller enters burst mode by turning the power switch on and off for intervals, utilizing an error signal and an offset current generator to enhance the error signal magnitude and reduce noise, thereby regulating output power effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous switching is used to regulate output power, then output regulation is maintained, but power consumption increases and noise susceptibility increases at no load or low load conditions
Solution Approach 1:
The patent implements burst mode operation where the controller periodically activates the power switch in intervals rather than continuous switching. During no load or low load conditions, the controller enters burst mode by turning the power switch on for a predetermined period, then off for a predetermined period, thereby reducing average power consumption while maintaining output regulation through periodic energy transfer to the output capacitor.
2Reliability
If continuous switching is used to regulate output power, then output regulation is maintained, but noise susceptibility of error signal increases at no load or low load conditions
Solution Approach 1:
By transitioning from continuous switching to periodic burst mode operation, the patent reduces the frequency of switching events during no load or low load conditions. This periodic activation reduces electromagnetic interference and noise susceptibility of the error signal while maintaining adequate output regulation through the energy stored in the output capacitor during the off intervals.
3Use of energy by moving object
If burst mode is implemented to reduce power consumption, then power consumption decreases, but output regulation precision may deteriorate
Solution Approach 1:
The patent incorporates a feedback mechanism where the controller monitors the output voltage and adjusts the burst mode parameters accordingly. The controller determines when to enter and exit burst mode based on load conditions, and within burst mode, it regulates the duty cycle during active intervals to maintain precise output voltage regulation despite the periodic switching nature, thereby preventing deterioration of regulation precision.
Data Source
AI summary
A controller for use in a power converter includes a load sensing circuit coupled to output an error signal in response to a feedback signal representative of an output of the power converter. The error signal is representative of a load coupled to an output of the power converter. A burst mode control circuit is coupled to output a burst mode control signal in response to the error signal. An offset current generator circuit is coupled to output an offset current in response to the error signal. A drive circuit is coupled to control switching of a power switch to control a transfer of energy from an input of the power converter to the output of the power converter in response to the error signal, the burst mode control signal, the offset current, and a current sense signal representative of a current through the power switch.