SMPS Ripple Shaping via Phase-Shifted Parallel Trains
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Solution Overview
Problem
Switching-mode power supplies (SMPS) face challenges in reducing current ripple, which affects capacitor selection and design, leading to conflicting trends between higher efficiency and increasing switching frequency, resulting in increased switching losses or larger system size, and often requiring expensive high-performance semiconductors.
Innovation Solution
A controller circuit generates a ripple shaping current complementary to the estimated output current ripple, using a combination of active phases and an auxiliary phase to reduce ripple at the combined output current, allowing for lower switching frequencies and the use of cheaper, lower-performance semiconductors, while shifting the frequency spectrum to higher frequencies for simplified filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If switching frequency is increased to reduce current ripple, then current ripple is reduced, but switching losses increase and system size increases
Solution Approach 1:
The power supply is divided into multiple parallel power trains operating at different phases. By segmenting the single power train into N parallel trains with phase shifts, the current ripple is reduced through constructive interference cancellation, while each individual train operates at lower switching frequency reducing switching losses.
Solution Approach 2:
The patent combines multiple power trains with different phase shifts to create a composite power delivery system. The composite current waveform from N parallel trains produces a ripple reduction effect equivalent to higher switching frequencies, but achieved at lower individual switching frequencies.
2Object-affected harmful factors
If switching frequency is increased to reduce current ripple, then current ripple is reduced, but system size increases
Solution Approach 1:
The system is segmented into N parallel power trains, each contributing to the total power delivery. This segmentation allows the use of larger inductors and capacitors at lower frequencies, achieving the same ripple reduction as high-frequency single-phase systems but with distributed, potentially more compact architecture.
Solution Approach 2:
The patent employs periodic phase shifting among N parallel power trains, where each train operates with a phase shift of 360/N degrees. This periodic action creates a composite waveform with reduced ripple amplitude, allowing lower switching frequencies and smaller magnetic components.
3Reliability
If duty cycle is controlled to regulate voltage/current, then voltage regulation is achieved, but ripple control becomes complex
Solution Approach 1:
The controller receives feedback about the combined output current and adjusts the duty cycles of individual power trains accordingly. This feedback mechanism maintains voltage regulation while the phase-shifted architecture naturally reduces ripple, simplifying the control complexity compared to single-phase high-frequency systems.
Solution Approach 2:
Each power train in the parallel configuration serves multiple functions: power delivery, ripple cancellation through phase shifting, and individual duty cycle control for regulation. This multi-functionality reduces the overall control complexity by distributing regulation tasks across multiple independent but coordinated channels.
Data Source
AI summary
A controller circuit for a switch-mode power supply (SMPS). The controller circuit is configured to generate, with a plurality of phases, a combined output current at a supply node to supply a load, determine a ripple shaping current complimentary to an estimated ripple at the combined output current using a number of active phases of the plurality of phases that generate the combined output current, and generate, with an auxiliary phase, the ripple shaping current at the supply node to reduce ripple occurring at the combined output current.