Theoretical Analysis of Carrier PWM Algorithms For Multilevel Inverters With Unbalanced DC Voltages
Tài liệu: Phân tích lý thuyết của thuật toán sóng mang PWM cho bộ biến tần đa cấp với điện áp DC không cân bằng.
This paper presents a generalized carrier PWM algorithm for controlling NPC multilevel inverters on consideration of variable dc-voltage sources. Simplicity of algorithms, possible applying to any level inverters are the advantages of the proposed PWM method. The ability of separate control of PWM modes, dc voltage balancing (common mode) and ac voltage balancing in a carrier PWM modulator presents an another favorable feature. Correlation between Space vector PWM and Carrier based PWM methods has been investigated. It will be shown that switching characteristics of
multilevel inverters can be simply described in a nominal switching diagram of two-level inverter. The problem of linear overmodulation will be also included. The validity of proposed algorithms has been demonstrated by simulation results.