Buck-Boost Power Transmission for DC Microgrid Using PMSM AC Motor Drive With Continuous Input and Output Currents

Reconfiguring the AC motor drive system into a three-phase parallel bidirectional Buck/Boost converter is a widely adopted reuse scheme for DC microgrids. However, this topology faces several challenges, including current discontinuity, the requirement for neutral point extraction from the permanent magnet synchronous motor (PMSM), and constraints on the voltages at the input and output ports. Therefore, this paper proposes a novel reconfiguration topology featuring continuous input and output currents, Buck-Boost output capability, and no need for motor neutral point connection. In the structure, the topology needs a few additional components, with a small cost increase. Due to power mismatch, the intermediate capacitor in DC-DC converter mode has voltage fluctuation, which affects the system performance. Therefore, a power compensation control method (PCCM) is proposed to improve the system response speed and stabilize the voltage. Meanwhile, through PCCM to actively control the voltage of the intermediate capacitor, a smaller intermediate capacitor can be used to further reduce the cost. Finally, the hardware experiment on a PMSM drive system is carried out to verify that the proposed topology and method are correct under various operating conditions.