Controllable Energy Store Charging via Transformer Rectification
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Solution Overview
Problem
Conventional energy storage systems in electric vehicles and wind turbines face reliability issues due to the series connection of battery cells, where a single cell failure can cause the entire system to fail, leading to potential safety hazards and system breakdowns.
Innovation Solution
A charging system that uses controllable energy storage devices with full-bridge switching elements to rectify AC voltage from a charging transformer, eliminating the need for a separate rectifier unit and allowing for controlled charging current through adjustable voltage settings in energy supply branches, thereby ensuring constant charging current across phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If battery cells are connected in series to achieve high overall voltage, then the voltage requirement is met, but the system reliability deteriorates because a single cell failure causes the entire energy store to fail
Solution Approach 1:
The energy store is divided into multiple independent battery module strings, where each string contains series-connected battery modules. This segmentation ensures that a failure in one string does not affect other strings, maintaining system reliability while achieving required voltage levels through series connection within each string.
Solution Approach 2:
Each battery module within the strings is equipped with an associated controllable coupling unit that can independently control that specific module. This local control capability allows individual modules to be managed separately, preventing local failures from propagating to the entire system and maintaining overall reliability.
2Power
If additional battery cells are connected in parallel to increase maximum current, then the current capability is improved, but the device complexity and cost increase
Solution Approach 1:
The controllable coupling units serve multiple functions: they control individual battery modules, enable parallel/series reconfiguration of battery strings, and can provide pulse-controlled inversion for the electrical machine. This multi-functionality increases current capability without proportionally increasing system complexity.
Solution Approach 2:
The battery system allows dynamic reconfiguration of battery module strings through controllable coupling units, enabling the system to adapt its electrical configuration (series/parallel arrangements) based on power and energy requirements, thereby achieving high current capability without fixed complex wiring.
3Ease of manufacture
If a separate rectifier unit is added to the charging system, then the AC voltage rectification is improved, but the installation space and cost increase
Solution Approach 1:
The rectifier function is merged with the existing controllable coupling units of the battery modules. These coupling units, already present for battery control, are utilized to perform AC voltage rectification during charging, eliminating the need for a separate rectifier unit and reducing installation space and cost.
Solution Approach 2:
The controllable coupling units serve dual purposes: controlling battery modules during operation and functioning as rectifiers during charging. This multi-functionality eliminates redundant components, specifically removing the need for a separate rectifier unit while maintaining full rectification capability.
4Device complexity
If the charging system uses existing stator windings as charging inductances, then the number of additional components is reduced, but the inductance value may be insufficient
Solution Approach 1:
The charging system utilizes the existing stator windings of the electrical machine as charging inductances, allowing the system to charge itself without requiring external inductance components. This self-service approach reduces component count while maintaining charging functionality.
Solution Approach 2:
The stator windings serve as intermediary inductances between the charging transformer and the battery system. These windings naturally provide the required inductance for current build-up and reduction phases during charging, eliminating the need for separate inductance components.
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 solution enhances system reliability by preventing entire energy store failure, reduces costs and installation space, and allows for efficient charging without additional components in vehicles, ensuring safe and continuous operation.
Implementation Method 1
a charging transformer (10) with a primary winding and a secondary winding (9)
Implementation Method 2
the switching elements (7), which are configured in a full-bridge topology, can be controlled such that they perform a rectifier function
Implementation Method 3
each comprising a plurality of series-connected electrical energy storage cells (5) and a coupling unit (6), which is assigned to the electrical energy storage cells (5) of the energy storage module (4)
Data Source
Figure 1
AI summary
The invention relates to a system for charging at least one energy storing cell (5) in a controllable energy store (2) that is used to control and supply electric energy to an n-phase electric machine (1), wherein n = 1. The controllable energy store (2) has n parallel energy supply branches (3-1, 3-2, 3-3), each of which has at least two serially connected energy storing modules (4), each said energy storing module comprising at least one electric energy storing cell (5) with a corresponding controllable coupling unit (6). The energy supply branches (3-1, 3-2, 3-3) can be connected to a reference bus (T-), and each energy supply branch can be connected to a phase (U, V, W) of the electric machine (1). The coupling units (6) bridge the respective corresponding energy storing cells (5) or connect same into the respective energy supply branch (3-1, 3-2; 3-3) dependent on control signals. The aim of the invention is to allow at least one energy storing cell (5) to be charged. This is achieved in that a neutral point (S) of the electric machine (1) and the reference bus (T-) can be connected to a secondary side (9) of a charging transformer (10).