Charger/discharger with high voltage conversion ratio for second-life batteries in charge stations for electric river boats

Abstract

Batteries play a fundamental role in the energy transition to renewable sources since they are the principal electrical energy storage devices on the market. Also, batteries enable cleaner and more efficient navigation for river transport transition. If the ships use batteries, they can significantly reduce their polluting gas emissions, contributing to environmental sustainability. The above is especially important in sensitive areas where pollution can have a considerable negative impact. Therefore, battery chargers have become essential devices for this purpose. The main requirement of a battery charger is high efficiency; however, it is also essential to ensure low current ripple in the battery current to ensure stable charging and avoid damage. This work proposes a battery charging system consisting of a filter of the battery current ripple, formed by an interleaved configuration of two boost converters; it also has a regulator of the DC bus voltage through a boost converter. The solution gives the system a high gain and allows the connection of batteries to high-voltage DC buses while reducing the current ripple, increasing the charger's efficiency, taking it to values above 95% while regulating the DC bus voltage to 48 V with a settling time lower than 1 ms and 1.65% of overshoot. The results show the possibility of connecting the charger to a DC bus with a single battery, avoiding batteries series connections, and removing problems related to battery unbalances. In addition, the low current ripple generated by this solution avoids the accelerated degradation caused by high current ripples produced in traditional battery chargers.