Electolytic capacitorless 3-level inverter with diode front end for PMSM drive

This paper proposes control of 3-level inverter with small DC-link capacitance and grid filter inductance for high speed motor drive system where regeneration and hold-up time are unnecessary. The controller consists of three simultaneously operating sub-controllers; High speed motor controller for flux weakening and maximum torque per ampere (MTPA) control, neutral voltage controller for DC-link voltage balancing, and active damping controller for DC-link stabilization. They are devised to operate in given DC-link voltage with their restricted voltage regions, avoiding interference among them. The analysis and design of each sub-controller and over all integration of them is discussed. The feasibility and performance of proposed control method is verified experimentally.