Digital Implementation of Z-source Neutral Point Clamped Inverter Using 8-bit Microcontroller

2014 ◽  
Vol 1 (4) ◽  
pp. 26-31
Author(s):  
Lara Amild ◽  
◽  
Christal Saji ◽  

2021 ◽  
Author(s):  
Weixing Feng

For most medium voltage high power applications, Neutral Point Clamped (NPC) three-level inverter is a preferred choice due to its advantages such as low cost, light weight and compact size. Space vector modulation is widely used in real-time digital control for power converters. It is especially suitable for use in NPC multilevel inverters due to its good harmonic profile, flexibility and easy digital implementation. This thesis focuses on the space vector modulation for high power three-level NPC inverter, where the switching frequency of the semiconductor devices is nominally below 1 OOOHz to reduce the power loss of the switching devices. The conventional space vector modulation (SVM) scheme for the three-level NPC inverter produces even order harmonics in the output voltages, which are not desirable for most industrial applications. In this thesis, the mechanism of even order harmonic generation is analysed. A new space vector modulation scheme, which can eliminate all the even order harmonics, is proposed. The performance of the new design is investigated and simulation results are provided for the verification purpose. The harmonic and THD profiles are compared with those of the conventional SVM scheme. The elimination of even order harmonics is achieved at the expense of a slight increase in the switching frequency. The proposed space vector modulation scheme can be applied to other types of converters for the even order harmonic elimination. An algorithm is developed to mitigate the neutral point potential deviation, which is a common problem in the NPC inverters. The simulation results show that this algorithm is suitable for both conventional and the proposed space vector modulation schemes.



2014 ◽  
Vol 986-987 ◽  
pp. 1858-1863
Author(s):  
Gang Han ◽  
Jian Wen Zhang ◽  
Xu Cai

This paper focuses on the digital experimental system for neutral-point-clamped three-level converter. First, SVM’s digital implementation method is studied. As neutral-point voltage unbalance is an inherent problem for this topology, a practical capacitor voltage balance method is present. This method uses a variable factor as the small vectors’ adjustment coefficient, which is calculated by PI controller with capacitor voltage deviation. Then, a digital modular control system is proposed, in which both hardware and software system structures are designed in modular. The digital control system adopts high speed optical-fiber communication between a master controller and multiple sub-controllers, and realized the effective and rapid control of the experimental prototype finally.



2021 ◽  
Author(s):  
Weixing Feng

For most medium voltage high power applications, Neutral Point Clamped (NPC) three-level inverter is a preferred choice due to its advantages such as low cost, light weight and compact size. Space vector modulation is widely used in real-time digital control for power converters. It is especially suitable for use in NPC multilevel inverters due to its good harmonic profile, flexibility and easy digital implementation. This thesis focuses on the space vector modulation for high power three-level NPC inverter, where the switching frequency of the semiconductor devices is nominally below 1 OOOHz to reduce the power loss of the switching devices. The conventional space vector modulation (SVM) scheme for the three-level NPC inverter produces even order harmonics in the output voltages, which are not desirable for most industrial applications. In this thesis, the mechanism of even order harmonic generation is analysed. A new space vector modulation scheme, which can eliminate all the even order harmonics, is proposed. The performance of the new design is investigated and simulation results are provided for the verification purpose. The harmonic and THD profiles are compared with those of the conventional SVM scheme. The elimination of even order harmonics is achieved at the expense of a slight increase in the switching frequency. The proposed space vector modulation scheme can be applied to other types of converters for the even order harmonic elimination. An algorithm is developed to mitigate the neutral point potential deviation, which is a common problem in the NPC inverters. The simulation results show that this algorithm is suitable for both conventional and the proposed space vector modulation schemes.







2015 ◽  
Vol 9 (1) ◽  
pp. 253-262
Author(s):  
Liu Zhongfu ◽  
Zhang Junxing ◽  
Shi Lixin ◽  
Yang Yaning

As for the wide application of arc suppression coil to the grounding in neutral point of mine high voltage grid, grid leakage fault rules and harmonic characteristics of the neutral point grounding system through arc suppression coil are analyzed, the selective leakage protection program “zero-sequence voltage starts, fifth harmonics of grid zerosequence voltage and zero-sequence current are extracted for phase comparison” is proposed, and corresponding fifth harmonic extraction circuit and power direction discrimination circuit are designed. The experimental results show that the protective principle applies not only to the neutral point insulated power supply system, but also to the power supply system in which neutral point passes arc suppression coil, which can solve selective leakage protection problems under different neutral grounding ways, improving the reliability of selective leakage and guaranteeing the stability of the action value.



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