Thiele-Small Parameter Identification And Fit Quality
T/S software fits an equivalent model to measured data; it does not read permanent numbers directly from the driver.
Measured, fitted, and derived
| Layer | Examples |
|---|---|
| measured | terminal voltage, current, impedance, DC resistance, added mass, box volume, displacement |
| fitted | blocked electrical impedance, motional branch, loss and creep model terms |
| derived | Fs, Qes, Qms, Qts, Vas, Mms, Cms, Rms, Bl, efficiency |
Fit quality is part of the result
Overlay measured and modelled impedance, inspect residuals, record warnings, and state the frequency range and inductance model. A neat parameter table can still come from a poor fit.
State dependence
Re changes with temperature; suspension compliance has memory and creep; orientation can reveal rocking; conductive motor parts complicate inductance; multiple resonances can exceed a simple lumped model.
Compare platforms responsibly
DATS, REW, manufacturer data, and advanced analyzers may use different stimulus, models, secondary methods, environmental inputs, and fitting strategies. Compare the complete method before judging disagreement.
Small-signal boundary
Use the result for low-frequency linear modelling near rest. Do not use it alone to declare excursion, distortion, thermal, voltage, or power limits.