Multi-phase DC-DC Converter Current Balancing via Phase Node Sensing
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Solution Overview
Problem
Multi-phase DC-DC converters face efficiency degradation due to unbalanced currents caused by component mismatches between phases, existing solutions either share load currents or average sensed signals, but these methods are inefficient in maintaining balanced channel currents.
Innovation Solution
A multi-phase DC-DC converter system comprising switching sets, output inductors, a sense circuit, and a PWM generator that senses phase node signals, generates error signals, and adjusts PWM signals to balance channel currents by comparing reference voltages with output voltages and summing difference signals with ramp signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional current sharing methods are used in multi-phase DC-DC converters, then load currents are distributed among phases, but conversion efficiency degrades due to unbalanced currents caused by component mismatches
Solution Approach 1:
The patent implements a feedback mechanism where sense circuits continuously monitor the current in each phase, and the PWM generator adjusts the duty cycle of each phase based on the sensed current information. This closed-loop feedback system dynamically compensates for component mismatches and maintains balanced current distribution, thereby improving conversion efficiency while ensuring current balance reliability
Solution Approach 2:
The patent replaces conventional mechanical or analog current sharing methods with a digital signal processing approach. The PWM generator uses digital calculations to compute the average current from sensed signals and generates adjusted PWM duty cycles for each phase, substituting traditional current sharing mechanisms with a more precise digital control system that improves both efficiency and balance
2Reliability
If load currents are shared between phases using summing circuits and scaling circuits, then current balance is achieved, but device complexity increases
Solution Approach 1:
The patent merges the current sensing, averaging, and PWM generation functions into an integrated control system. The sense circuits for multiple phases are combined into a single averaging network within the PWM generator, which simultaneously processes all sensed signals and generates all PWM outputs. This consolidation reduces the number of separate summing circuits and scaling circuits needed, thereby reducing device complexity while maintaining current balance
Solution Approach 2:
The PWM generator is designed as a universal control unit that performs multiple functions: it senses currents from all phases, calculates the average current, generates error signals, and produces PWM signals for all phases. This multi-functional approach eliminates the need for dedicated summing and scaling circuits for each phase, reducing overall circuit complexity while ensuring reliable current balance
Data Source
AI summary
A multi-phase DC-DC converter is provided. A plurality of switching sets are coupled to an output, wherein each switching set includes a phase node. A plurality of inductors are separately coupled between the phase nodes and the output. A sense circuit has a plurality of sense units separately coupled to the phase nodes, each sensing a signal from the corresponding phase node and generating a sensing signal. A PWM generator includes a plurality of subtracting units, each subtracting a first signal from one of the sensing signals to generate a difference signal, wherein the first signal is generated by summing each of the sensing signals divided by a predetermined value except for the one of the sensing signals. The PWM generator generates a plurality of PWM signals to balance the currents of the inductors according to the difference signals.