Multiphase Converter Light Load Efficiency via Phase Segmentation
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Solution Overview
Problem
Current multiphase converters for portable applications face high power consumption due to current sense circuitry during light load conditions, necessitating a method to boost efficiency by reducing quiescent current.
Innovation Solution
The solution involves disabling or partially disabling current sense circuitry in one power stage, using a smaller power stage with higher inductance, and implementing a power management circuitry with a driver output and stage selection circuit to generate an enable signal only under light load conditions, thereby reducing RMS current and quiescent current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current sense circuitry is used in all power stages, then system reliability and control precision are improved, but power consumption increases during light load conditions
Solution Approach 1:
The multiphase converter is segmented into two distinct power stage types: N-1 phases use full current sense circuitry for reliable control, while the 1st phase uses a simplified current sense-free design. This segmentation allows the system to maintain overall reliability through the N-1 reliable phases while the single phase-1 stage handles light load conditions efficiently without current sense consumption.
Solution Approach 2:
Different quality configurations are applied to different phases: phases 2 through N use high-quality current sense circuitry for precise control and reliability, while phase-1 uses a low-quality current sense-free configuration optimized for light load efficiency. This local quality differentiation resolves the contradiction by matching each phase's characteristics to its specific operational requirements.
2Use of energy by moving object
If current sense circuitry is disabled to reduce power consumption, then light load efficiency is improved, but measurement precision and control accuracy deteriorate
Solution Approach 1:
The system segments current measurement functions across different phases: phase-1 operates without current sense circuitry for maximum efficiency, while phases 2 through N maintain full current sense capability for precise measurement and control. This segmentation allows the system to sacrifice measurement precision in only one phase while maintaining it in others.
Solution Approach 2:
The controller acts as an intermediary that compensates for the lack of current sense data in phase-1 by using information from other phases and implementing control algorithms that can operate effectively without direct current measurement from phase-1, thus maintaining overall system control accuracy despite the missing measurement in one phase.
3Device complexity
If all power stages use regular inductance values, then design simplicity is maintained, but RMS current and power loss increase during light load
Solution Approach 1:
The system applies different inductance characteristics to different phases: phase-1 uses higher inductance specifically optimized for light load conditions to reduce RMS current and associated losses, while phases 2 through N use regular inductance values suitable for their operational characteristics. This local optimization resolves the contradiction by tailoring inductance to specific phase requirements rather than using a uniform design.
Data Source
AI summary
A method for boosting light load efficiency for multiphase converters through disabling at least partially a current sense circuit, disabling partial equivalent elements of one of power stages, using small size equivalent element for one of power stages, and through utilizing higher inductance, compared to other regular phases, to reduce RMS current.