Fuzzy-Lowpass Filter Based Control of Super Capacitor to Enhance the Battery Life Under Large Intermittent Residential Loads

– This paper presents the improvement of battery performance in a standalone household electrical system by integrating supercapacitors (SC) and control circuits to extend battery life. Intermittent load current in a residential is generated by household appliances such as refrigerators, ovens, microwaves, charging, and air conditioners. It causes pulse loads with rapid and deep discharge of batteries, reducing their lifespan. The residential system configuration consists of a photovoltaic with a Hybrid Energy Storage System (HESS) battery and SC. By selecting a fully active topology, a bidirectional buck-boost converter manages the energy between the battery and SC. The proposed method controls Fuzzy-Proportional Integral (PI) and Lowpass Filter (LPF) in order to reduce the load pulse height and battery discharge depth. The SC absorbs load pulses through the converter while the battery serves a continuous load. A fuzzy logic control is applied, prior to the LPF in order to maintain DC bus voltage stability and regulate the SC current. The cut-off frequency of the LPF is varied to shave the height of the pulses. The PI control optimizes the duty cycle of the Bidirectional Converter (BDC) when charging and discharging the battery and SC. Simulations show that the combination of fuzzy-PI and LPF control effectively reduces the battery's Depth of Discharge (DOD). At the LPF cut-off frequency (FC) of 10 Hz, the battery cycle data is 2120 and rises to 2868 or extends the battery life from 5.81 to 7.86 years at FC 5 Hz.