Switched-Capacitor Power Conversion Module for Automatic Voltage Balancing
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Solution Overview
Problem
Three-level Buck DC-DC power converters face challenges in automatically achieving voltage balance across flying capacitors and current equalization across balance units, which affects the efficiency and stability of power conversion.
Innovation Solution
A power conversion module with a multi-stage structure, including basic and balance units, where the switching frequency and duty ratios are carefully controlled to ensure voltage balance and current equalization, using a two-stage or three-stage configuration with specific switch and capacitor arrangements to maintain steady-state operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional three-level Buck DC-DC power converter topology is used, then power conversion function is achieved, but voltage balance across flying capacitors and current equalization across balance units cannot be automatically achieved
Solution Approach 1:
The patent implements self-service by designing a power conversion module where the flying capacitors and balance units automatically achieve voltage balance and current equalization through their inherent circuit topology and switching mechanisms, without requiring external control intervention. The module structure itself provides the balancing function, making the system self-regulating.
Solution Approach 2:
The patent applies segmentation by dividing the power conversion module into multiple balance units, each with its own flying capacitors and switching elements. This modular segmentation allows independent voltage balancing in each unit while achieving overall system current equalization, simplifying the control strategy by localizing the balancing function.
2Loss of energy
If voltage balance and current equalization are achieved through control strategies, then conversion efficiency improves, but additional control circuitry and complexity are required
Solution Approach 1:
The module structure enables self-service operation where the flying capacitors automatically maintain voltage balance and balance units achieve current equalization through their inherent topology and switching patterns. This eliminates the need for additional control circuitry to enforce balancing, reducing overall system complexity while maintaining high conversion efficiency.
Solution Approach 2:
The flying capacitors serve as intermediaries that naturally balance voltages between different parts of the circuit through their charging and discharging cycles. This passive intermediary mechanism achieves voltage balance without requiring active control intervention, reducing the need for complex control circuitry.
3Reliability
If multi-stage structure with balance units is implemented, then automatic voltage balance and current equalization are achieved, but device structure becomes more complex
Solution Approach 1:
The patent segments the power conversion system into modular balance units, each containing flying capacitors and switching elements. This segmentation creates a structured multi-stage configuration that achieves automatic voltage balance and current equalization through the interaction of identical modular units, making the complexity manageable and systematic.
Solution Approach 2:
Each balance unit in the multi-stage structure is designed as a universal module that performs multiple functions: power conversion, voltage balancing, and current equalization. This multi-functionality reduces the need for separate dedicated components for each function, optimizing the structure despite the multi-stage configuration.
Data Source
AI summary
A power conversion module can include: an i-th level structure comprising 2i-1 basic units, a second terminal of each basic unit in each level structure respectively connected to first terminals of two basic units in a next level structure, where a first terminal of a first basic unit in a first-level structure is used as a first terminal of the power conversion module; an N-th level structure comprising 2N-1 balance units, where second terminals of each balance unit are connected as a second terminal of the power conversion module, and second terminals of each basic unit in an (N−1)th level structure are respectively connected to first terminals of two balance units in the N-th level structure; and where each basic unit comprises a switched capacitor circuit, N is a positive integer greater than or equal to 2, i is a positive integer, and 1≤i≤N−1.