Ante Komljenovic

Battery/ultracapacitor test setup control system design and verification

This paper presents the control system design for a battery/ultracapacitor experimental setup developed for the purpose of experimental characterization and modeling of battery and ultracapacitor-based energy storage systems. The setup comprises two IGBT-based two-quadrant DC/DC power converters. The low-level battery/ultracapacitor current controllers and the DC link voltage controller are implemented in a relatively inexpensive programmable logic controller (PLC), while the high-level control and data acquisition are based on the National Instruments DAQ board and National Instruments LabView software. The proposed test setup control system is verified experimentally for a wide range of operating regimes including preliminary battery/ultracapacitor experimental characterization tests.

Battery current and voltage control system design with charging application

This paper presents the design of battery charging control system suitable for different battery types. A PI controller-based battery current control system is designed with the aim of achieving robust control system behavior over a wide range of battery internal resistance variations. In order to enhance the battery current control system performance, an adaptation mechanism comprising a Kalman filter-based battery internal resistance estimator has been designed and tested. The current control system is commanded by a superimposed battery voltage controller aimed at bringing the battery terminal voltage to the fully-charged state while also limiting the maximum battery charging current. The effectiveness of the proposed battery charging cascade control system has been verified experimentally on the battery test setup for a VRLA battery and LiFePO4 cell.

A design of DC bus control system for EVs based on battery/ultracapacitor hybrid energy storage

This paper presents the design of a control system suitable for EV DC bus voltage sag compensation based on the voltage PI controller and load current feedforward compensator. The superimposed PI controller and feedforward compensator references are distributed between the inner battery and ultracapacitor current-controlled DC/DC converters so that the ultracapacitor takes on the highly-dynamic (transient) current demands, while the battery covers for steady-state loads. In order to avoid deep discharges of the ultracapacitor, the DC bus control system is also equipped with auxiliary state-of-charge (SoC) controller. The functionality of the superimposed DC bus voltage control system and inner current and SoC control loops has been verified by means of simulations and experimentally on a downscaled battery/ultracapacitor experimental (NIL) setup.

Dual Kalman filter-based SoC/SoH estimator for an ultracapacitor module

This paper presents the design of a dual adaptive Kalman-filter-based state and parameter estimator of an ultracapacitor module suitable for state-of-charge (SoC) and state-of-health (SoH) estimation purposes. A lumped-parameter resistive-capacitive (RC) electrical circuit representation has been used in the design of both estimators. In the case of state estimator a second-order disturbance model has been used for charge balancing current modeling purposes, while in the case of parameter estimator, a time series model of ultracapacitor is extended with a generalized disturbance model describing balancing current effects. The effectiveness of the dual Kalman filter-based SoC/SoH estimator has been verified by means of computer simulations and experimentally on the dedicated ultracapacitor test setup.

Dual EKF-based state and parameter estimator for a LiFePO4 battery cell

This work presents the design of a dual extended Kalman filter (EKF) as a state/parameter estimator suitable for adaptive state-of-charge (SoC) estimation of an automotive lithium–iron–phosphate (LiFePO₄) cell. The design of both estimators is based on an experimentally identified, lumped-parameter equivalent battery electrical circuit model. In the proposed estimation scheme, the parameter estimator has been used to adapt the SoC EKF-based estimator, which may be sensitive to nonlinear map errors of battery parameters. A suitable weighting scheme has also been proposed to achieve a smooth transition between the parameter estimator-based adaptation and internal model within the SoC estimator. The effectiveness of the proposed SoC and parameter estimators, as well as the combined dual estimator, has been verified through computer simulations on the developed battery model subject to New European Driving Cycle (NEDC) related operating regimes.

Experimental characterization and development of a SoC/SoH estimator for a LiFePO 4 battery cell

This paper presents the results of experimental characterization of an automotive LiFePO4 battery cell for the purpose of building of a control-oriented battery equivalent electrical circuit model suitable for designing a combined state-of-charge (SoC) and state-of-health (SoH) estimator. The SoC/SoH estimator design has been based on the time-series representation of the battery model utilized within the extended Kalman filter (EKF) parameter estimator, with SoC reconstruction based on the known open-circuit voltage vs. discharged charge curve. In order to provide a consistent SoC estimate during low-excitation intervals, EKF-based estimation has been combined with a Coulomb (charge) counting approach. The effectiveness of the proposed SoC/SoH estimator has been verified by means of computer simulations on the developed battery model for different battery operating regimes.

Single phase AC inverter current PR control with auxiliary PI controller for DC current suppression

This paper presents the design of a current control system for a single-phase grid-tied inverter equipped with a LCL grid-side filter, which is suitable for inverter DC current component suppression. For that purpose, a proportional-resonant (PR) controller of principal harmonic current component has been designed. This is followed by the design of DC current component estimator based on second-order generalized integrator (SOGI) concept, which is used for DC current suppression by means of a dedicated proportional-integral (PI) controller. Both the PR and PI controllers are designed based on the damping optimum criterion, which results in straightforward analytical expressions for controller parameters. The effectiveness of the proposed dual-current controller-based system is verified by means of simulations.

Design of EKF-based SoC estimator for an ultracapacitor module

This paper presents the design of ultracapacitor module state-of-charge (SoC) estimator based on an Extended Kalman Filter (EKF). A lumped-parameter resistive-capacitive (RC) electrical circuit representation of ultracapacitor module has been used for EKF design, wherein non-linear capacitance effects have been included through SoC-dependent capacitance term, while cell balancing effects were modeled by a second-order disturbance model. The proposed EKF-based SoC estimator has been compared to an LTI model-based Kalman filter as SoC estimator, and verified by means of computer simulations and experimentally on the dedicated ultracapacitor test setup.