NPV Control Method by Injecting Zero Sequence Voltage for Three Level NPC Inverter

2018 ◽  
pp. 205-211
Author(s):  
Bo Gong ◽  
Yang Liu
Keyword(s):  
Control Method ◽  
Zero Sequence ◽  
Zero Sequence Voltage

scholarly journals A Carrier-Based Discontinuous PWM Strategy of NPC Three-Level Inverter for Common-Mode Voltage and Switching Loss Reduction

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 3041
Author(s):  
Guozheng Zhang ◽  
Yingjie Su ◽  
Zhanqing Zhou ◽  
Qiang Geng
Keyword(s):  
Pulse Width Modulation ◽  
Control Method ◽  
Balance Control ◽  
Neutral Point ◽  
Switching Loss ◽  
Major Drawback ◽  
Common Mode ◽  
Common Mode Voltage ◽  
Zero Sequence ◽  
Zero Sequence Voltage

For the conventional carrier-based pulse width modulation (CBPWM) strategies of neutral point clamped (NPC) three-level inverters, the higher common-mode voltage (CMV) is a major drawback. However, with CMV suppression strategies, the switching loss is relatively high. In order to solve the above issue, a carrier-based discontinuous PWM (DPWM) strategy for NPC three-level inverter is proposed in this paper. Firstly, the reference voltage is modified by the twice injection of zero-sequence voltage. Switching states of the three-phase are clamped alternatively to reduce both the CMV and the switching loss. Secondly, the carriers are also modified by the phase opposite disposition of the upper and lower carriers. The extra switching at the border of two adjacent regions in the space vector diagram is reduced. Meanwhile, a neutral-point voltage (NPV) control method is also presented. The duty cycle of the switching state that affects the NPV is adjusted to obtain the balance control of the NPV. Still, the switching sequence in each carrier period remains the same. Finally, the feasibility and effectiveness of the proposed DPWM strategy are tested on a rapid control prototype platform based on RT-Lab.

scholarly journals Power Control and Fault Ride-Through Capability Analysis of Cascaded Star-Connected SVG under Asymmetrical Voltage Conditions

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2361
Author(s):  
Muxuan Xiao ◽  
Feng Wang ◽  
Zhixing He ◽  
Honglin Ouyang ◽  
Renyifan Hao ◽  
...  
Keyword(s):  
Power Control ◽  
Reactive Power ◽  
Control Method ◽  
Balance Control ◽  
Positive Sequence ◽  
Maximum Phase ◽  
Power Oscillation ◽  
Fault Ride Through ◽  
Zero Sequence ◽  
Zero Sequence Voltage

The cascaded H-bridge static var generator (SVG) has been employed to provide reactive power and regulate grid voltages for many years because of its good modularity, easy scalability, and improved harmonic performance. A novel cluster-balancing power control method combining negative-sequence currents and zero-sequence voltage is proposed to redistribute the unbalanced active powers and eliminate the power oscillation under asymmetrical conditions. Simultaneously, the dynamic performance of the SVG power balance control can be improved under asymmetrical conditions with the zero-sequence voltage expression derived in this paper. On the basis of the proposed method, the fault ride through capability of star-connected SVG under asymmetrical conditions is compared among active power oscillation elimination (APOE), reactive power oscillation elimination (RPOE), and balanced positive sequence current (BPSC) injection references calculation strategies from the perspective of the zero-sequence voltage, maximum phase voltage, and maximum phase current. The method provides the theoretical reference for power control under asymmetric conditions and the analysis results show that under asymmetrical conditions, the current of BPSC is minimal and symmetrical, while the RPOE has the least voltage and no zero- sequence voltage needs to be injected. Finally, the results of simulation and experiment have been given to verify the theoretical studies.

scholarly journals A Novel Neutral-Point Potential Balance Strategy for Three-Level NPC Back-to-Back Converter Based on the Neutral-Point Current Injection Model

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yingjie Wang ◽  
Haiyuan Liu ◽  
Wenchao Wang ◽  
Kangan Wang
Keyword(s):  
Balance Control ◽  
Neutral Point ◽  
Control Algorithms ◽  
Model Based ◽  
Point Potential ◽  
Injection Model ◽  
Zero Sequence ◽  
Flow Through ◽  
Dc Bus ◽  
Zero Sequence Voltage

The neutral-point (NP) potential balance control in three-level neutral-point-clamped (NPC) back-to-back converter is a research nodus. Its current strategies are the same as the strategies of a single three-level NPC converter. But the strategies do not give full play to its advantages that the neutral-point current can only flow through the connected midlines in both sides of the converter but does not flow through the DC-bus capacitors. In this paper, firstly the NP potential model based on the NP current injected is proposed. It overcomes numerous variable constraints and mutual coupling in the conventional model based on the zero-sequence voltage injected. And then on this basis, three NP-potential balance control algorithms, unilateral control, bilateral independent control, and bilateral coordinated control, are proposed according to difference requirements. All of these algorithms use the midlines rather than the DC-bus capacitors to flow the NP current as much as possible. Their control abilities are further quantitatively analyzed and compared. Finally, simulation results verify the validity and effectiveness of these algorithms.

Sign in / Sign up

Export Citation Format

Share Document