The Modeling of Lead-Acid Battery by Frequency-Response Characteristics

Impedance-based and circuit-parameter-based battery models for HEV power systems

“…Generally, it adopts an equivalent circuit model with two positive-and negative-side capacitances, as in Figure 2(a), in order to express all battery capacitance components; however, there is no difference between the series connection of the two parallel connected RC circuits in Figure 2(a) and the single equivalent parallel connected RC circuit in Figure 2(b) (Buller et al, 2005;Conway, 1999;Kim, 2006;Lee et al, 2002;Yusivar et al, 2002). Instead, the doubling of the calculated equivalent single capacitance is the total capacitance based on the stored energy in the battery because the two series connected capacitances are presented as a single equivalent capacitance.…”

“…After a one hour standstill, the frequency response of the battery was measured. The current response to voltage input was measured in order to maintain the SOC, which is different from measuring the voltage response to current input in the existing papers (Chen and Rincon-Mora, 2006;Kim, 2006;Yusivar et al, 2002). This is because the SOC is changed with the polarization voltage; in other words, the electromagnetic force (emf) of the battery is changed by charging and discharging even though an accurate sine wave or pulse with offset is applied to current input, and because the precise detection of output voltage is difficult as the OCV of the battery is irregular and includes noise.…”

“…Many techniques for battery modeling (Buller et al, 2005;Chen and Rincon-Mora, 2006;Conway, 1999;Kim, 2006;Lee et al, 2002;Lee and Sunwoo, 2001;Wu et al, 2001;Yusivar et al, 2002) have been developed with electrochemical models, mathematical models, and the electrical models that are treated in this paper. One of the most common methods is to evaluate electrical equivalent circuit models composed of circuit parameters, while another is an impedance-based electrical model.…”

“…Because accurate circuit parameters are unknown, it becomes difficult to calculate heat generation, loss, efficiency, and power factors, and to design cell balancing circuits and filters, which need information on the resistive, capacitive, and inductive components of battery. Therefore, this paper also presents a modeling method that expresses the battery with electric equivalent circuit elements by employing the Bode plot and admittance transfer function concepts (Yusivar et al, 2002).…”

“…The battery equivalent circuit model employed in this paper includes inductance, which has not been regarded as an important circuit parameter previously, and this value has not yet been extracted precisely (Conway, 1999;Yusivar et al, 2002). The uncertain influence of data measurement is suppressed by considering the inductance; therefore, this model has the advantage that the inductive impedance increase caused by the high switching frequency of the DC/ DC converter is taken into account.…”