Controllable Energy Storage System for Electric Machine Charging
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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 failed cell can cause the entire system to fail, leading to potential safety threats and system downtime.
Innovation Solution
A controllable energy storage system with n parallel energy supply branches, each comprising series-connected energy storage modules with coupling units that can be controlled to bypass or switch energy storage cells, connected to a DC voltage intermediate circuit via a bidirectional bridge rectifier, allowing for step-up or step-down converter functions during charging, ensuring reliable energy distribution and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If battery cells are connected in series to achieve high voltage, then the voltage requirement is met, but the system reliability deteriorates because a single failed cell causes the entire energy store to fail
Solution Approach 1:
The energy store is divided into multiple energy supply branches, each with series-connected battery cells. Controllable coupling units are inserted in parallel across each cell or module, allowing independent control of each branch. This segmentation enables the system to maintain operation in one branch even when another branch fails, resolving the reliability issue while preserving high voltage capability.
Solution Approach 2:
The system dynamically changes the electrical configuration parameters by switching coupling units between different states (bypassing individual cells or entire branches). This allows the system to adapt its topology based on operational needs and failure conditions, maintaining high voltage output while improving reliability through reconfigurability.
2Power
If additional battery cells are connected in parallel to increase maximum current, then the current capability is improved, but the device complexity increases
Solution Approach 1:
The controllable coupling units serve multiple functions: they bypass individual failed cells, bypass entire failed branches, enable charging of specific cells or modules, and provide control for the electrical machine. This multi-functionality achieves high current capability and improved reliability without proportionally increasing device complexity, as the same switching components perform multiple roles.
3Reliability
If the electrical machine is decoupled during charging, then the charging reliability is improved, but the operational continuity deteriorates
Solution Approach 1:
The system maintains continuous useful action by keeping the electrical machine connected during charging operations. The controllable coupling units allow selective charging of specific energy storage modules while the machine remains operational, eliminating the need to decouple the machine and ensuring uninterrupted operation while maintaining charging reliability.
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 system enhances the reliability of energy storage by allowing for simultaneous charging of energy storage cells across multiple branches, minimizing hardware requirements and costs, while ensuring continuous operation and safety by decoupling the electrical machine during charging, thus preventing system failures.
Implementation Method 1
The energy supply branches of the controllable energy storage device and the phases of the electrical machine are connected to a DC voltage intermediate circuit via a controllable n-phase bidirectional bridge rectifier
Implementation Method 2
at least one high-side switch of the bridge rectifier together with the stator windings of the electric machine during a charging process is analogous to a step-down converter and/or the coupling units, which are assigned to energy storage cells to be charged, together with the stator windings of the electric machine during a charging process are analogous to a step-up converter
Data Source
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AI summary
The invention relates to a system for charging at least one power cell (5) in a controllable energy store (2) used for controlling and supplying electric power to an n-phase electric machine (1), where n = 1. The controllable energy store (2) has n parallel power supply branches (3-1, 3-2, 3-3), each of which includes at least two serially connected energy storage modules (4). Each energy storage module comprises at least one electric power cell (5) having an associated controllable coupling unit (6) and is connected to a reference bus (T-) and to one respective phase (U, V, W) of the electric machine (1). The coupling units (6) disconnect the respective power supply branch (3-1, 3-2; 3-3), bridge the associated power cells (5), or connect the associated power cells (5) to the respective power supply branch (3-1, 3-2, 3-3) in accordance with control signals. The power supply branches (3-1, 3-2, 3-3) of the controllable energy store (2) and the phases (U, V, W) of the electric machine (1) are connected to an intermediate DC circuit (10) by means of a controllable bidirectional n-phase rectifier unit (9). The reference bus (T-) of the controllable energy store (2) is connected to a reference bus (B) of the intermediate DC circuit (10). The intermediate DC circuit (10) can be electrically connected to a charging device (12).