Decoupling Model Predictive Controlled Three-Level Noninverting Buck-Boost Converter Applied in DC Energy Storage System

To solve the bi-directional power control issue under wide range voltage changes on both sides of the DC bus and energy storage battery in the DC energy storage system (ESS), this paper proposes a multi-objective decoupling MPC (MOD-MPC) strategy for the three-level noninverting Buck-Boost converter (TLNBC). The mathematical model of TLNBC based on the voltage difference of split capacitors is first studied, solving the problem of multi branch modeling of split capacitor voltage. On this basis, a MOD-MPC power control strategy with dual-carrier modulation method is proposed by analyzing the relationship between system current and split capacitor voltage sharing control. The optimal control variables solution is directly obtained by solving the cost function, achieving independent control of system current and split capacitor voltage sharing, and greatly reducing computational load. The decoupling MPC controlled TLNBC can operate in Buck and Boost modes when energy is transmitted in any direction catering to various scenarios while exhibiting favorable control performance. The effectiveness of the converter and control strategy is verified through experiments.