Battery Cell Balancing via DC-AC-DC Conversion
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Solution Overview
Problem
Existing battery systems face challenges in stabilizing voltage variations across battery cells, which affects efficient charging and discharging operations, particularly when integrating with renewable energy sources and grid power systems.
Innovation Solution
A battery system with a battery cell balancing unit that includes a controller to generate AC current from a DC reference current, a transformer, and a rectifier circuit with switching units to selectively connect to battery cells, ensuring voltage balance across cells and facilitating efficient power conversion and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional battery systems are used without active balancing, then the system structure is simpler, but voltage variations among battery cells increase, reducing charging and discharging efficiency
Solution Approach 1:
The battery system is segmented into multiple independent balancing circuits, each handling specific battery cells. The controller divides the battery pack into groups and applies individualized balancing strategies to each group, allowing voltage variation compensation without requiring complete system redesign.
Solution Approach 2:
A DC-AC-DC power conversion intermediary is introduced between the battery cells and the balancing circuit. The converter transforms DC voltage from battery cells into AC voltage, then back to DC for regulated charging, enabling precise voltage control while isolating the complexity of the balancing mechanism from the battery cells themselves.
2Reliability
If voltage balancing is not implemented, then the system is simpler to operate, but voltage variations affect the stability of charging and discharging operations
Solution Approach 1:
The controller continuously monitors voltage levels of individual battery cells and dynamically adjusts balancing currents in real-time. This closed-loop feedback mechanism ensures voltage variations are compensated as they occur, maintaining stable charging and discharging operations without requiring complex manual intervention.
Solution Approach 2:
The balancing system dynamically adapts its operation based on real-time battery cell states. The controller modifies balancing currents, switching frequencies, and power conversion parameters dynamically to match changing voltage conditions, ensuring reliable operation under varying load and state-of-charge conditions.
3Manufacturing precision
If a battery cell balancing unit with DC-AC-DC conversion is added, then voltage variations are reduced, but the device complexity increases
Solution Approach 1:
The power conversion system is designed to perform multiple functions: voltage balancing, energy storage, and power regulation. The same DC-AC-DC converter infrastructure used for balancing also serves as the energy storage interface, eliminating the need for separate balancing hardware and reducing overall system complexity.
Solution Approach 2:
The voltage balancing function is merged with the existing power conversion and energy storage infrastructure. The controller integrates balancing operations with normal charging and discharging cycles, using the same power electronic components for both energy transfer and voltage equalization, thereby achieving precise voltage control without adding dedicated balancing hardware.
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 effectively reduces voltage variations among battery cells, enhancing the stability and efficiency of charging and discharging operations, thereby improving the overall performance of battery systems in energy storage and power supply applications.
Implementation Method 1
a transformer having an input coil configured to receive the AC current, and an output coil coupled to the input coil
Implementation Method 2
a rectifier circuit having a rectifier connected to the output coil
Data Source
AI summary
A battery system is disclosed. The battery system includes a plurality of battery cells, and a battery cell balancing unit, configured to adjust voltages across each of the battery cells to reduce variation among the voltages across the battery cells. The battery cell balancing unit includes a controller configured to receive a DC reference current and to generate an AC current based on the DC reference current, a transformer, a rectifier circuit including a rectifier connected to the output coil, and a switching unit including a plurality of switches, each configured to selectively connect the rectifier to one of the battery cells.