MA – Neutral Point Balancing Control of the NPC Inverter with DPWM and Optimized Pulse Patterns

The ever-increasing number of electric vehicles (EVs) is a remarkable ongoing change in the industry. Currently, most EVs use the primary two-level converter (B6) with a dc-link voltage of up to 800V. To reach larger power ratings and faster charging (up to MW), some manufacturers are looking for a powertrain solution with a dc-link voltage beyond 1 kV. In such a case, three-level converters, like neutral point clamped (NPC) converters, are preferred since the high voltage stress is distributed over the series-connected switches. However, additional control requirements arise for multilevel converters, such as the balancing of the neutral point (NP) potential around zero.

The Task for the student: a) Literature review on the NP balancing control methods; b) Develop suitable control algorithm for different modulation strategies, e.g. discontinuous pulse width modulation (DPWM) and optimal pulse patterns (OPP); c) Implement and evaluate the algorithms with simulation.

Required prior knowledge: Fundamentals about power electronics, fundamentals of control engineering, pulse width modulation.

Required software skill: MATLAB/Simulink or PLECS.

Bearbeiter: Zhepei Zheng

Betreuer: Yang Qifan

Verantwortlicher: Prof. Dr.-Ing. Martin März