Multi-Mode DC-DC Converter for Battery Cell Segmentation
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Solution Overview
Problem
Existing DC-DC converters for multi-cell batteries face inefficiencies due to high inductance or high switching frequency requirements when stepping down or up large voltages, leading to large components or significant losses, and multi-level converters suffer from reduced efficiency under high loads due to series switches.
Innovation Solution
A power supply system with a switching DC-DC converter that selectively operates in multiple modes by coupling an energy storage element between different numbers of cells and the output, optionally using an inductor and switched capacitor converters, and incorporating a single switch in series with the cells to manage voltage and current efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a buck converter is used to step down battery voltage, then voltage regulation is achieved, but large inductance or high switching frequency is required leading to large components or large losses
Solution Approach 1:
The patent divides the battery pack into multiple series-connected cell groups (e.g., first group with N cells, second group with M cells) and provides separate DC-DC converters for each group. This segmentation allows each converter to operate at lower voltage levels, reducing switching losses and enabling smaller inductors while maintaining overall voltage regulation capability.
Solution Approach 2:
The patent introduces an intermediate voltage dimension by tapping power from intermediate nodes between cell groups rather than directly from the full battery voltage. This creates a multi-level voltage architecture that reduces the voltage swing required by individual converters, thereby reducing switching losses and component size.
2Loss of energy
If multi-level DC-DC converters are used to reduce voltage conversion losses, then switching losses are reduced, but output current efficiency decreases due to two or more switches in series
Solution Approach 1:
Instead of using multiple switches in series within a single converter path, the patent segments the power conversion function across multiple parallel converter paths. Each converter handles a portion of the total power, allowing single-switch configurations per path and eliminating the series switch bottleneck while maintaining reduced switching losses.
Solution Approach 2:
The patent combines multiple DC-DC converter outputs in parallel to deliver the total required output current. This merging approach allows each converter to operate independently with high efficiency, and their combined output achieves the required power level without the efficiency penalty of series switches.
3Power
If high switching frequency is used in buck converter, then voltage regulation is improved, but component size increases and losses increase
Solution Approach 1:
The patent introduces intermediate voltage levels between the full battery voltage and the output voltage, creating a multi-stage conversion process. This dimensional voltage breakdown allows each stage to operate at lower voltage differences, enabling larger inductance values and lower switching frequencies while maintaining good voltage regulation.
Solution Approach 2:
By changing the operating voltage parameters of the DC-DC converters through multi-level architecture, the patent enables operation at optimized switching frequencies and inductance values that reduce component size and losses while maintaining regulation precision.
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 approach reduces inductor current ripple and switching losses, enhances transient load response, and minimizes component size and cost by optimizing switching frequency and voltage ratings, while maintaining high efficiency even under high loads.
Implementation Method 1
a switching DC-DC converter for providing a regulated voltage at an output and comprising an energy storage element
Implementation Method 2
a switched capacitor converter arranged to transfer charge between cells
Data Source
AI summary
A power supply has a multi-level DC-DC converter and a battery pack with two or more cells provided in series. The switching DC-DC converter provides a regulated voltage at an output. The converter has an energy storage element. The switching regulator is designed to selectively operate in two or more different modes. It switches between a first mode where one cell is connected (between battery and inductor of the converter), and the converter functions like a single cell buck converter and a second mode where two cells are connected in series and the converter functions like a two series cell buck converter. In general, any number of cells and modes can be provided, with successive cells being connected in series in each mode.