Battery knowledge · Transport and modelling
Reduced-order model
A simplified version of a detailed model that keeps its dominant behaviour with far fewer states. The single-particle model is one reduction of the Newman model; others use polynomial profiles, Padé approximation or proper orthogonal decomposition. A ROM gives a BMS internal quantities, such as lithium concentration in the electrodes, that an equivalent circuit model cannot.
- Abbreviation
- ROM
- Also called
- model order reduction
Example
Transport and modelling: an example situation
The same concentration difference across 10 μm gives ten times the gradient across 100 μm; at equal D, first-law flux magnitude is ten times greater.
Read Reduced-order model alongside Battery management system in this context. The electronics and software that keep a battery inside its safe window: measuring every cell voltage and many temperatures, estimating SOC and SOH, balancing cells, computing current limits, controlling the contactors and reporting over the vehicle network.
Use in Lemonergy
Lemonergy Studio blocks
Observe an RC time constant
An RC circuit uses source, resistor, capacitor and reference blocks.
Blocks to use
- Controlled voltage source
Applies voltage
Inputs & settings
- voltageV
- Resistor
Sets resistance
Inputs & settings
- resistanceOhm
- Capacitor
Stores charge
Inputs & settings
- capacitanceF
- initialVoltageV
- Electrical reference
Sets zero potential
Inputs & settings
- Connect p to reference net
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
Example. From zero initial voltage with a 1 V step, ideal capacitor voltage is about 0.632 V at 1 s and 0.865 V at 2 s.
Observe. Doubling resistance or capacitance doubles the time constant.
This generic circuit does not identify cell parameters from measurements.
Open the RC example →References & further reading
Further reading on this topic
These sources provide broader context; they are not presented as citations for every statement in this entry.
- Modeling of Galvanostatic Charge and Discharge of the Lithium/Polymer/Insertion Cell
Marc Doyle, Thomas F. Fuller, John Newman · Journal of The Electrochemical Society · 1993
Topic background · Porous-electrode transport and insertion-cell modeling; foundational work rather than a specification for a particular commercial cell.
- Quantities, Units and Symbols in Physical Chemistry, 3rd edition, 2nd printing
IUPAC · 2011
Topic background · Physical-chemistry notation, thermodynamics, electrochemistry and transport quantities.