Inductance-Based Balancing Unit for Energy Cell Voltage Symmetry

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Solution Overview

Problem

Series connections of energy cells, such as capacitors or accumulators, face performance degradation due to differences in voltage, internal resistance, and capacitance caused by manufacturing variations and external influences, leading to inefficient energy storage and utilization.

Innovation Solution

A balancing device utilizing a DC chopper with inductance for energy transfer between energy cells, along with a measuring device and control system, allows for precise voltage determination and energy balancing by charging weaker cells from stronger ones, reducing energy loss and thermal power loss, and improving the efficiency of energy storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If passive balancing devices based on resistance circuits are used, then the voltages of energy cells can be adjusted to one another, but a large amount of energy is converted into heat causing high thermal power loss

Engineering Contradiction:
Improvevoltage balanceVSAvoidthermal power loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent introduces a DC chopper with inductance as an intermediary device between energy cells to transfer energy. Instead of directly dissipating excess energy as heat through resistors, the inductance stores energy temporarily and releases it to cells that need it, reducing thermal power loss while maintaining voltage balance

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the balancing approach from passive resistance-based voltage equalization to active inductance-based energy transfer. By controlling the switching states of the DC chopper, the system dynamically adjusts energy distribution based on real-time voltage measurements, improving both efficiency and balance precision

Inventive Principle:
Principle #35Parameter changes

2Productivity

If active balancing devices with switchable resistors are used, then energy transfer between cells can be controlled, but the device complexity increases

Engineering Contradiction:
Improveenergy transfer efficiencyVSAvoidbalancing device structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The DC chopper circuit serves multiple functions: it acts as both an energy transfer mechanism and a voltage measurement interface. The same inductance and switching components used for energy balancing also enable voltage determination through magnetic field sensing, reducing the need for separate measurement circuits and simplifying the overall device structure

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the energy transfer function and voltage measurement function into a single integrated DC chopper system. The measuring device determines voltages based on the magnetic field of the inductance, merging sensing and actuation functions that would traditionally require separate circuits

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If voltage measurement is performed separately from energy transfer, then precise voltage determination can be achieved, but additional measuring components and system complexity are required

Engineering Contradiction:
Improvevoltage determination accuracyVSAvoidmeasuring and control system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The inductance of the DC chopper serves dual purposes: it is the core component for energy transfer during switching operations and simultaneously serves as the sensing element for voltage measurement. The measuring device detects voltages by sensing the magnetic field generated by the inductance, eliminating the need for separate voltage sensing circuits

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The solution enables efficient balancing of energy cells with high precision, reducing energy loss and thermal power loss, and improving the overall performance and power-to-weight ratio of energy storage systems.

Implementation Method 1

a DC chopper with an inductance for a first and a second electrical energy cell, the DC chopper being designed to take up energy from the first energy cell into the inductance in a first switching state and in a second switching state to deliver the absorbed energy from the inductance to the second energy cell

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a measuring device for determining the voltages of the energy cells and a control device for activating the DC chopper in the two switching states as a function of the determined voltages, the measuring device being set up to determine the voltages of the energy cells on the basis of a magnetic field of the inductance

Methodology Applied
Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentEP2577839B1Balancing unit, energy store and balancing method
Publication Date: 2018.03.21 SIEMENS MOBILITY GMBH
  • EP2577839B1 patent drawingFigure 1~2
  • EP2577839B1 patent drawingFigure 3
  • EP2577839B1 patent drawingFigure 4~5

AI summary

The invention relates to a balancing unit for a first and a second electric energy cell, comprising a dc-dc converter with an inductance, the dc-dc converter being designed to receive energy in a first switched state from the first energy cell to the inductance and to emit the received energy in a second switched state from the inductance to the second energy cell. The balancing unit also comprises a measuring unit for determining the voltages of the energy cells and an actuating unit for actuating the dc-dc converter in the two switched states in conjunction with the voltages that have been determined, the measuring device being designed to determine the voltages of the energy cells on the basis of a magnetic field of the inductance. An energy store comprises a plurality of energy cells that are interconnected in series and the aforementioned balancing unit. The invention also discloses a balancing method for balancing electric cells, which includes a computer program product.