Electrochemical Impedance Spectroscopy Using Power Converter for Renewable Energy Applications

Electrochemical devices such as batteries as an energy storage system (ESS) and photovoltaics (PV)
have been recognized and widely used to improve green and sustainable energy. The battery energy storage
system (BESS) has significantly increased the penetration of renewable energy generation, more electric
aircraft, and smart home appliances. While PV is expected to support a higher proportion of the global
energy demand. However, the diagnosis/prognosis of lithium-ion batteries (LIB) and PV health and safety
has become the main concern in estimating their lifetime.
Electrochemical impedance spectroscopy (EIS) is a method to measure the impedance of
electrochemical devices. It measures by applying the alternating current (AC) voltage/current and then
measuring the current/voltage. In terms of characterization of LIB or estimating the state of health (SoH),
the EIS technique is superior to the others. By comparing the current and the new battery impedance, the
LIB characterization and SoH can be estimated.
In this comprehensive study, LIB impedance characterization is the main parameter that can be
utilized to investigate the expected LIB lifetime and internal temperature. The first approach is the
integration of battery impedance spectroscopy (BIS) into a battery management system (BMS) with a
reduced number of inductors and switch components compared to existing methods. In addition, this
proposed method presents an internal preheating mechanism, active state of charge (SoC) equalizer, and
BIS without an external power source so that no additional component is needed. An LC resonant has been
proposed for the LIB internal temperature measurement to measure the battery’s internal temperature. The
proposed method shows that the LC resonant tank can measure the three batteries, B1, B2, and B3 internal
resistance, and translate it to the batteries’ internal temperature without any internal or external temperature sensor.
Light intensity modulation impedance spectroscopy (LIMIS) is introduced for the PV impedance
measurement. The PV impedance is evaluated by a light-intensity modulation method. The light intensity
is controlled by modulating the LED using the synchronous buck converter. The benefit of using the LC
tank for the battery’s internal temperature is to reduce data processing since no window and Fast Fourier
Transform (FFT) is needed for this method. In addition, the proposed method measures the battery’s
internal temperature without any internal or external temperature sensor. The proposed method can
measure a new PV panel, a damaged panel, and a cycle PV panel impedance. This impedance value has a
strong relationship with the health of the PV panel and can be utilized to estimate the PV panel’s lifetime.