Modulated Model Predictive Current Control of Three-Level NPC Inverter with Overmodulation Capability

A modulated model predictive current control (M2PCC) strategy of a three-level neutral point clamped (NPC) inverter with overmodulation feature is presented in this paper. A discontinuous pulse width modulation (PWM) approach is used with predictive current control (PCC) to generate a switching sequence for the inverter. In the discontinuous PWM based PCC, a common mode voltage (CMV) is injected to the optimal output voltage of PCC to generate the reference voltage used in the modulation process. Similar to the fundamental PCC, only one optimal voltage vector is activated in a sampling interval. Due to simple calculations of CMV and the use of the aforementioned single voltage vector, the proposed M2PCC is simpler than the conventional M2PCC. Simulation results show that the proposed system yields good steady-state and transient responses in both linear and overmodulation regions with capacitor voltages balanced. The operation of the proposed system at different frequencies is also verified.