Design of digital sampling impedance bridge for battery impedance spectroscopy
Stanislav Mašlán
Abstract:
The paper describes design of a digital sampling impedance bridge dedicated for battery impedance spectroscopy. It suggests topologies capable of measurement of sub-milliohm impedances in full complex plane. Paper also shows measurement uncertainty contributions of the digitizer nonlinearity and coaxial network of the bridge including parasitic inductive and capacitive couplings in the network. Combined uncertainty of the bridge with common NI 9238 digitizer ranges from less than 20 μΩ/Ω to order of 0.01 % for voltage drop above 1 mV at the measured standard in a frequency range 0.01 Hz to 5 kHz. Angular errors can be as low as 1 μrad for frequencies below 1 kHz when measured voltage drops exceed 10 mV. The paper also presents experimental measurements showing capability to measure low impedances from 0.01 Hz to 5 kHz.
