Virtual Space Vector Pulse Width Modulation algorithm for three-level NPC converters based on the final element shape functions

This paper proposes a novel 3-phase asymmetric 3-level T-type NPC inverter and studies its PWM performance using a virtual space vector pulse width modulation control strategy. Firstly, the mathematical model and characteristics of this economical topology are described. Then, a virtual space vector approach is proposed to build a space vector diagram for designing SVPWM control. Similar to the conventional 3-level NPC inverter, the asymmetric inverter can also work with the neutral point voltage self-balancing in a fundamental period, which enables employment of this topology in various applications. Finally, simulation and experiment results under different load conditions have shown good output performance of the asymmetric 3-level topology. Similar tests are also performed on both conventional 2-level and 3-level inverters for comparison. For an almost similar number of different voltage vectors in the space vector diagram, the asymmetric 3-level topology can compete with conventional 3-level inverters for low-cost applications. The obvious benefit of the asymmetric 3-level inverter is a smaller number of switches devices while it can achieve output performance similar to that of the conventional 3-level. The comparative investigation also shows that the total loss given by SVPWM for the asymmetric 3-level configuration is lower than that of the traditional 3-level inverter.

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A Variable Switching Frequency Virtual Space Vector Pulse-Width Modulation Based on the Current Ripple Prediction

2019 IEEE Energy Conversion Congress and Exposition (ECCE) ◽

10.1109/ecce.2019.8912794 ◽

2019 ◽

Author(s):

Xingchen Zhao ◽

Shuang Zhao ◽

Zhe Zhao ◽

Fei Diao ◽

Yue Zhao ◽

...

Keyword(s):

Pulse Width ◽

Pulse Width Modulation ◽

Virtual Space ◽

Switching Frequency ◽

Space Vector ◽

Current Ripple

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Research on the Equivalent Virtual Space Vector Modulation Output of Diode Clamped N-level Converter under Multi-Modulation Carrier Modulation

Energies ◽

10.3390/en13153803 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3803

Author(s):

Yingjie He ◽

Chao Lei ◽

Yunfeng Liu ◽

Jinjun Liu

Keyword(s):

Theoretical Analysis ◽

Pulse Width ◽

Pulse Width Modulation ◽

Virtual Space ◽

Space Vector ◽

N Level ◽

Capacitor Voltage ◽

Multi Level ◽

Level Converter ◽

Relationship Of

Diode-clamped multi-level converters have DC-side capacitors in series, which will lead to the unbalance of DC-side capacitor voltage, the distortion of the output waveform, the increase of total harmonic distortion (THD), and even the damage of switching devices, which will make the system inoperable. The proposal of virtual space vector pulse-width modulation (VSVPWM) realizes the balanced control of the capacitor voltage, but when the output level of converter increases, the implementation of VSVPWM becomes very complicated, and the amount of calculation also increases greatly, thus hindering its application in the multi-level circuit. Compared with VSVPWM, the carrier-based pulse-width modulation (CBPWM) is simple to operate and easy to implement. If the equivalent relationship between CBPWM and VSVPWM can be found, the application of VSVPWM can be generalized to any level, and the advantages of VSVPWM can be fully utilized. This paper aims to study the inner relationship of VSVPWM and the multi-modulation carrier CBPWM (MCBPWM). After strict theoretical analysis, the equivalent relationship of VSVPWM and MCBPWM in the three-level and four-level and converter is realized by injecting the zero-sequence component into the modulation waves. Furthermore, the equivalent relationship between VSVPWM and MCBPWM is deduced to the N-level converter. Finally, the correctness of the relevant theoretical analysis is verified by the experiment.

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