Multi-port DC/DC Converter with Shared Inductor for Ripple Reduction
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Solution Overview
Problem
Current cascaded buck converter topologies suffer from high frequency switching ripple voltage at input ports, leading to capacitive current to ground in energy sources like solar panels or batteries, and require excessive energy storage components, increasing size, loss, and cost.
Innovation Solution
The multi-port converter topology features a double-input single-output configuration with a single filter inductor placement across inner switches, allowing for arbitrarily small high frequency switching ripple at all terminals, bidirectional energy exchange, and controlled power sharing among inputs, using interleaved switch operation and optional low-frequency voltage stacking mode to reduce component ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cascaded buck converter topologies are used, then voltage regulation and bidirectional energy transfer can be achieved, but high frequency switching ripple voltage occurs at input ports causing capacitive current to ground
Solution Approach 1:
The patent merges multiple buck converter cells into a unified multi-port converter structure where input capacitors are shared across ports. This consolidation reduces the number of independent filtering circuits while maintaining voltage regulation capability, thereby reducing overall switching ripple voltage at input ports compared to traditional cascaded topologies where each cell generates independent ripple.
Solution Approach 2:
The patent introduces a unified inductor as an intermediary element that couples multiple input ports to the output. This single inductor filters the combined switching ripple from all input ports, acting as a mediator that reduces high frequency voltage ripple more effectively than individual per-cell inductors in traditional cascaded converters.
2Adaptability or versatility
If traditional cascaded buck converter topologies are used, then multiple input ports can exchange energy with common output, but excessive energy storage components are required increasing size, loss, and cost
Solution Approach 1:
The patent combines multiple input capacitors into a shared capacitor network that serves all input ports simultaneously. Instead of requiring separate energy storage components for each converter cell as in traditional cascaded topologies, the unified structure uses shared capacitors and a single inductor, dramatically reducing the total quantity of energy storage components while maintaining the ability to handle multiple input ports.
Solution Approach 2:
The unified inductor and shared input capacitors serve multiple functions simultaneously: they filter switching ripple for all input ports, store energy for bidirectional power flow, and enable voltage regulation across multiple ports. This multi-functionality eliminates the need for redundant energy storage components required in traditional cascaded converters where each cell needs its own dedicated inductor and capacitor.
3Object-generated harmful factors
If multiple L-C filters are used in classical cascaded buck converter, then high frequency switching ripple voltage is reduced, but size and cost increase significantly
Solution Approach 1:
The patent merges the filtering function of multiple L-C filters into a single unified filtering structure using shared input capacitors and one inductor. This consolidation maintains the high frequency ripple filtering capability of traditional cascaded converters with multiple L-C filters, but achieves it with significantly fewer and smaller components, thereby reducing overall converter size and cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves reduced component ratings, lower losses, and cost while maintaining high flexibility, enabling full output voltage range capability and charge balancing across all possible output voltages, effectively addressing the limitations of traditional cascaded buck converters.
Implementation Method 1
The L-C low-pass filter is designed such that it attenuates the high frequency switching harmonics of vx and allows the output voltage Vout to be equal to the average value D·Vin
Implementation Method 2
An output L-C low-pass filter is employed when a small high frequency ripple for the output voltage is required
Data Source
AI summary
A module for interconnecting a pair of DC sources or a pair of DC loads into a DC bus includes: a first port for each source or load; a switching cell for each first port, each cell having a pair of terminals and a switching node; a second port operatively connected to the DC bus and having a pair of terminals, one of the pair of terminals of the second port being connected to one of the terminals of one of the cells and the other of the pair of terminals of the second port being connected to one of the terminals of the other of the cells; and a filter inductor connected between the switching nodes of the cells. Systems including the module and methods utilizing the system are also disclosed.