Simplified low-cost experimental setup for battery loss evaluation in MMC converters

When Modular Multilevel Converters (MMC) are fed by distributed battery modules, the degrees of freedom in the converter control algorithm can be exploited to reduce battery internal losses. To experimentally evaluate the goodness of a control strategy in terms of battery efficiency, the energy lost in all distributed batteries should be measured. This requires all the battery voltages to be measured and processed by Analog to Digital Converters (ADC) at a high sampling frequency. This aspect significantly impacts the circuitry cost and complexity and may be unfeasible in practice, especially for MMCs with a high number of modules. This paper proposes a simplified low-cost experimental setup whose complexity and cost are inversely proportional to the MMC total number of modules. The proposed system allows to evaluate the energy that would be lost in all the batteries of a generic MMC, regardless of the number of modules and of the control technique. The setup constitutes a practical tool to easily evaluate the impact of different MMC control strategies on battery losses, both for state-of-literature algorithms and novel research proposals. The simplified system is experimentally evaluated for different MMC control strategies and modulation techniques. The resulting battery losses are evaluated and compared with the trends theoretically derived by the state-of literature.