Multi-phase DC-DC Converter Current Sharing via On-Time Regulation
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Solution Overview
Problem
In multi-phase DC-DC converters, current sharing among phases is challenging due to biases in element characteristics, leading to inefficiencies and stability issues, as the on-time of switches can differ across phases, preventing effective current sharing without on-time regulation.
Innovation Solution
A control circuit and method that includes a comparing circuit, a trimming current generator, and multiple controllers to compare voltage feedback signals with reference signals, generate trimming current signals based on switching voltage signals, and regulate the on-time of controllable switches to equalize voltage and current differences across phases, ensuring balanced current sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If interleaved multi-phase power supply is used to provide large power and current, then power output capability is improved, but output current biases occur among multiple phases due to element characteristic variations
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors the on-time of switches in each phase and adjusts the driving signals accordingly. By detecting deviations in switch on-time caused by element characteristic variations, the controller dynamically compensates to maintain balanced current distribution across all phases, thereby resolving the current bias issue while preserving high power output capability.
Solution Approach 2:
The patent changes the operating parameters of each phase by adjusting the switch on-time individually. When element characteristic variations cause current imbalance, the controller modifies the on-time parameter for affected phases to equalize current distribution. This dynamic parameter adjustment allows the system to maintain both high power output and balanced current sharing despite manufacturing tolerances.
2Device complexity
If on-time regulation is not implemented, then device complexity is reduced, but current sharing control cannot be achieved among multiple phases
Solution Approach 1:
The patent implements a self-service mechanism where each phase's controller automatically monitors and adjusts its own switch on-time based on detected current balance conditions. The system uses the existing switching signals and element characteristics to generate appropriate correction signals without requiring external intervention or complex centralized control, thereby achieving reliable current sharing with minimal additional complexity.
Solution Approach 2:
The patent divides the control function into separate segments for each phase, with each controller independently managing its phase's switch on-time. This segmentation allows simple, modular control circuits to handle current sharing locally, avoiding the need for a single complex centralized controller while maintaining reliable current balance across all phases through coordinated operation.
Data Source
AI summary
A COT control circuit used for realizing current sharing in multi-phase DC-DC converter. The multi-phase DC-DC converter has N switching circuits, N controllers, and a trimming current generator receiving N switching voltage signals of the N switching circuits to generate N trimming current signals. The N trimming current signals are respectively sent to the N controllers to regulate on time of at least one controllable switch of each of the N switching circuits so as to finally realize current sharing in the multi-phase circuits.