The most important task of a battery management system on-board an electric
vehicle is the battery cell voltage measurement. It enables the system controller
to monitor the behavior and health of a battery pack, and respond appropriately,
ensuring the safety of a vehicle. In order to provide valid data samples without
external disturbances, an appropriate filter method should be implemented. In
the case of a battery management system integrated circuit TLE9018DQU, the
voltage measurement is based on the Delta-Sigma modulator. External filtering
with required frequency characteristics is currently not achievable, due to limitations
imposed by the passive balancing circuitry. For this reason, a discrete-time
filter can be implemented in the post-processing stage of the Delta-Sigma analogto-
digital converter. To provide an appropriate filtering method, the test bench
environment was designed in the course of this thesis. The test bench was set-up
using the MATLAB and the Simulink environment. A flexible configuration of
the Delta-Sigma ADC and either the FIR or the IIR filter implementation is provided.
Quantization of coefficients of a filter transfer function was integrated into
the test bench to simulate the behavior of an practical filter design. Settling time
of the IIR was evaluated and its possible improvements are discussed. At the end,
an explanation is given on how the IIR is superior to the FIR implementation in
the application for a TLE9018DQU integrated circuit.
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