Energy Storage Controller for Heterogeneous Cell Management
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Solution Overview
Problem
The combination of rechargeable batteries and supercapacitors is challenging due to their different characteristic voltage ranges, power capabilities, and energy storage capacities, leading to inefficiencies and safety issues in battery management systems, especially when cells of varying types and capacities are used, resulting in suboptimal performance and premature degradation.
Innovation Solution
A controller system that estimates the characteristics of each energy cell, such as power capability, storage capacity, and chemistry, allowing for independent adjustment of charging and discharging currents to synchronize cell operation, enabling the connection of cells of different types and capacities, and using bi-directional DC to DC converters to manage voltage and current, thereby optimizing the use of available components and prolonging cell life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cells of different types and capacities are connected together, then the versatility and adaptability of the energy storage system is improved, but the reliability and safety of the system deteriorates due to mismatched voltage ranges and power capabilities
Solution Approach 1:
The system divides the energy storage pack into multiple independent cell groups, each containing cells of the same type and capacity. This segmentation allows cells of different types (lithium-ion, lead-acid, nickel-metal hydride) to be connected in series while maintaining internal consistency within each group, thereby achieving versatility without compromising safety.
Solution Approach 2:
A microcontroller unit acts as an intermediary between the cells and the external environment. It monitors voltage, current, and temperature of each cell individually, and dynamically adjusts charging/discharging currents to prevent overcharge, over-discharge, and overheating conditions, ensuring safe operation of heterogeneous cell combinations.
2Power
If cells are connected in series to increase voltage output, then the power capability of the system is improved, but the productivity and energy utilization deteriorates due to the bottleneck effect of the weakest cell
Solution Approach 1:
The system dynamically adjusts the operating parameters (current, voltage, power) of each cell based on real-time monitoring of their state of charge, capacity, and health status. The microcontroller optimizes the charge/discharge current distribution to maximize the utilization of each cell's capacity, preventing the bottleneck effect and improving overall energy utilization while maintaining high power capability.
3Ease of manufacture
If traditional battery management systems are used with cells of varying capacities, then the ease of manufacture is improved, but the loss of energy increases due to inefficient charge/discharge cycles
Solution Approach 1:
The system implements continuous feedback monitoring of voltage, current, and temperature for each cell through ADC converters and temperature sensors. The microcontroller processes this feedback information and dynamically adjusts the charge/discharge currents to optimize energy efficiency, minimize losses, and extend cell lifespan, thereby reducing energy loss while maintaining ease of manufacture.
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 allows for optimal utilization of cells by synchronizing charge and discharge cycles, prolonging cell life, and enabling the formation of versatile energy storage packs from disparate components, reducing waste and enhancing the efficiency and longevity of energy storage systems.
Implementation Method 1
The energy storage device further comprises a bi-directional DC to DC converter for each cell slot, said DC to DC converters being controlled by the controllers
Data Source
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AI summary
An electrical energy storage device comprising: a plurality of energy cell slots for receiving energy cells (120); and a controller (130); wherein the controller is arranged to estimate a characteristic of a cell in each slot; and wherein the controller is arranged to apply charge and discharge currents to each cell slot dependent upon at least one estimated characteristic currently associated with that slot. The controller may be a single controller that controls all slots or it may be implemented as multiple controllers each controlling more than one cell slot or a controller for each slot. The characteristic may be one or more of: a power capability, a storage capacity, a cell impedance, an energy cell type and an energy cell chemistry. By estimating characteristics of the energy cells connected to the energy storage device, the system can adjust the charging/discharging currents applied to each cell to make the best use of the attached cells. Energy storage cells can vary greatly; rechargeable battery cells have high energy storage capacity, but lower power capabilities while super capacitors have lower energy storage capacity, but much higher power capabilities. Combinations of different types of cell are possible. To make optimal use of different cells, different charge/discharge currents may be applied. E.g.higher charge/discharge currents for super capacitors than rechargeable batteries. For combinations of batteries and super capacitors, it may be desirable (to limit battery degradation) initially to direct more current into the super capacitors to fully charge them before charging the rechargeable battery cells at a slower rate. During discharge, the higher power capability of the super capacitors allows them to handle power spikes and thus the controller may only drawon them when the power requirements exceed the capabilities of the rechargeable battery cells.