A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters

Jianguo Lyu; Wenbin Hu; Fuyun Wu; Kai Yao; Junji Wu

A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters

Vol. 15, No. 5, pp. 1207-1216, Sep. 2015

10.6113/JPE.2015.15.5.1207

Discontinuous pulse width modulation (DPWM)

Low frequency oscillation

Neutral-point voltage balancing

Three-level inverter

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Abstract

In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

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Cite this article

[IEEE Style]

J. Lyu, W. Hu, F. Wu, K. Yao, J. Wu, "A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters," Journal of Power Electronics, vol. 15, no. 5, pp. 1207-1216, 2015. DOI: 10.6113/JPE.2015.15.5.1207.

[ACM Style]

Jianguo Lyu, Wenbin Hu, Fuyun Wu, Kai Yao, and Junji Wu. 2015. A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters. Journal of Power Electronics, 15, 5, (2015), 1207-1216. DOI: 10.6113/JPE.2015.15.5.1207.