Multi-phase Converter Current Sharing Control
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Solution Overview
Problem
Multi-phase converters face challenges in equalizing current distribution among phases, leading to inefficiencies, reduced component lifespan, and potential device destruction due to uneven current provision.
Innovation Solution
A multi-phase converter system with a current share adjusting circuit that uses a current sense amplifier and error amplifier to adjust the PWM duty cycle based on sensed output currents, ensuring each phase contributes equally to the total output current, employing a clock circuit for out-of-phase timing and a PWM generator to control switching circuits across a DC bus voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-phase converters are used to reduce ripple and output capacitance size, then efficiency and power density improve, but uneven current distribution among phases occurs leading to reduced component lifespan and potential device destruction
Solution Approach 1:
The patent implements a current sharing control mechanism where each phase's output current is sensed and fed back to a control circuit. The control circuit compares the sensed current with a reference current and adjusts the PWM duty cycle of each phase accordingly. This closed-loop feedback system dynamically balances the current distribution among phases, preventing any single phase from carrying excessive current while maintaining high power delivery efficiency.
2Quantity of substance
If phases are operated sequentially with different switching times to reduce ripple, then output capacitance size is reduced, but current imbalance occurs among phases
Solution Approach 1:
The patent employs dynamic current sharing control where the PWM duty cycles of different phases are continuously adjusted based on real-time current sensing. The control circuit modifies the switching characteristics of each phase dynamically to achieve balanced current distribution. This dynamic adjustment allows the system to maintain ease of operation with sequential phase switching while automatically correcting current imbalances as they occur.
Data Source
AI summary
A multi-phase converter has a plurality of switching circuits each controlled by a phase controller and each providing a switched output voltage to an output node of the converter. Each switching circuit sequentially provides a switched output voltage to the output node at which an output voltage of the converter is developed. A clock circuit provides a plurality of out of phase clock signals to determine when each switching circuit provides the switched voltage to the output node. Each switching circuit is connected across a DC bus voltage. A first error amplifier compares a first signal proportional to the output voltage of the converter at the output node with a second signal comprising a first reference voltage and produces a first error signal. A PWM generator compares the first error signal with a third signal comprising a ramp signal from a ramp signal generator circuit and produces a pulse width modulated signal to control the on-times of a switch of the connected switching circuit. A current share adjusting circuit has a current sense amplifier for each switching circuit sensing the output current provided by each switching circuit, and provides a signal proportional to the sensed output current.