Multi-phase converter control for voltage undershoot reduction
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Solution Overview
Problem
Multi-phase converters experience significant undershoot in output voltage due to delays in control mechanisms when reducing the number of switching circuits under power operation during load current reductions.
Innovation Solution
A control circuit and method that introduce a nonlinear control signal, which increases to a preset value and then decreases with a preset slew rate when the number of switching circuits under power operation decreases, to manage the turning ON of switching circuits based on output voltage and reference signals, thereby reducing voltage undershoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of switching circuits under power operation is reduced to optimize efficiency, then energy consumption is improved, but output voltage undershoot increases due to control delay
Solution Approach 1:
The nonlinear control signal is generated in advance before the switching circuits are turned off. When phase shedding is detected, the control circuit immediately generates a nonlinear control signal that increases to a preset value and then decreases with a preset slew rate, proactively compensating for the upcoming voltage drop before it occurs, thus preventing significant undershoot while enabling efficient phase reduction
Solution Approach 2:
The control circuit dynamically changes the control signal parameters based on the operating state. A nonlinear control signal is introduced that varies its amplitude and slew rate according to the phase shedding event, creating a time-varying control signal that optimizes the turning-on characteristics of switching circuits during transient states, thereby balancing efficiency and voltage stability
2Productivity
If auto phase shedding is implemented to optimize efficiency, then productivity is improved, but control complexity increases
Solution Approach 1:
The control circuit employs parameter changes by introducing a nonlinear control signal whose amplitude and slew rate are dynamically adjusted based on the phase shedding state. This allows the system to achieve efficient auto phase shedding while managing control complexity through a structured approach to signal generation and switching control
Data Source
AI summary
A multi-phase converter has a plurality of switching circuits coupled in parallel and a control circuit. The control circuit provides a set signal to successively turn ON the switching circuits under power operation based on an output voltage, a reference signal and a nonlinear control signal. When a number of switching circuits under power operation decreases, the nonlinear control signal increases to a preset value from an initial value, and then the nonlinear control signal decreases to the initial value with a preset slew rate.