This multilevel, cascaded H-bridge (CHB) converter reduces DC current harmonic ripples, mitigating current variation in DC to AC power conversion, increasing battery lifetimes and stability of battery-powered circuits. Battery energy storage systems (BESSs) play an important role in power grids, renewable energies, smart grids, and electric vehicle charging stations. Accordingly, multilevel converters have widely been used in AC to DC current conversions for power grids. Multilevel converters can connect to battery energy storage systems to charge or discharge batteries or control the active or reactive power injected into the power grid. However, conventional multilevel converters have slightly inferior harmonic performances, causing significant drawbacks when used with power grids involving batteries. There is a need to develop a multilevel converter able to balance the DC harmonics with the AC side of a converter, meeting the requirements of the Institute of Electrical and Electronic Engineers (IEEE) 519 standard, and increasing converter efficiency.
Researchers at the University of Florida have developed a multilevel, cascaded H-bridge (CHB) converter to reduce harmonic discrepancies between the AC and DC cells. This results in increasing battery lifespans, eliminating the need for DC current sensors, reducing size requirements of passive filters, and stabilizing battery-powered circuits.
A cascaded H-bridge (CHB) converter balances and mitigates the current harmonic ripples in the DC to AC power conversion, increasing converter efficiency and battery lifespans
This multilevel, cascaded H-bridge (CHB) converter uses the AC current harmonics to control and reduce the current harmonic ripples on the DC side of the converter. This mitigates current variation in DC to AC power conversion. The model is a single-phase, grid-tied CHB converter, balancing and mitigating zero and even-order harmonics of the DC sides of the CHB. By doing this, the DC link voltage ripples are reduced without increasing the AC side filtering inductance of the converter. This capability confers additional flexibility in controlling the CHB converter and allows the converter to block fault currents, which arise from a short circuit between the positive and negative DC terminals.