A Study on Offset Voltage-Based Discontinuous Modulation Applicable to Single Phase Neutral-Point-Clamped Three-Level PWM Converter

2018 ◽  
Vol 21 (1) ◽  
pp. 30-40
Author(s):  
Min-Sup Song
Keyword(s):  
Single Phase ◽  
Neutral Point ◽  
Pwm Converter ◽  
Offset Voltage

scholarly journals Analytical Modeling of Neutral Point Current in T-type Three-level PWM Converter

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1324
Author(s):  
Kui-Jun Lee
Keyword(s):  
Analytical Model ◽  
Neutral Point ◽  
Control Loop ◽  
Pwm Converter ◽  
Voltage Balancing ◽  
Loop Design ◽  
Offset Voltage ◽  
Three Phase ◽  
Effective Voltage ◽  
Balancing Control

Since a T-type three-level PWM converter has several intrinsic advantages, it has been researched for various applications such as grid-connected converter systems. However, it necessarily requires an additional voltage control loop for balancing the upper and the lower DC-link voltage. To satisfy this requirement, an offset voltage is widely used to provide a neutral point current without affecting other variables such as total DC-link voltage and three-phase input current. However, these methods are mostly based on the averaged value between the applied offset voltage and the neutral point voltage or current, and there is no exact analytical model. Therefore, in this paper, the exact theoretical relationship between the offset voltage and the neutral point current is analyzed. This result can be expected to be useful for an effective voltage balancing control loop design as well as the better understanding of the whole system operation. The validity of the obtained analytical model is verified by simulation and experimental results.

scholarly journals Analysis of Allowable Unbalanced Load Conditions for T-type Three-Level PWM Converter

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5969
Author(s):  
Kui-Jun Lee
Keyword(s):  
Low Voltage ◽  
Experimental Tests ◽  
Neutral Point ◽  
Stable System ◽  
System Operation ◽  
Pwm Converter ◽  
Conduction Loss ◽  
Offset Voltage ◽  
Unbalanced Load ◽  
Load Conditions

Since a T-type three-level PWM converter has several advantages in terms of harmonics and conduction loss, it has been widely adopted for various low voltage applications. However, a neutral point voltage control is necessarily required for stable system operation, and an offset voltage can effectively provide the required neutral point current under unbalanced load conditions. Nevertheless, all types of unbalanced loads cannot be accommodated; in other words, there is a limitation on how much unbalanced load conditions can be allowed. Therefore, this paper analyzed the maximum allowable unbalanced load conditions in the T-type three-level PWM converter. This result can be properly utilized for an effective design verification considering unbalanced load conditions as well as a comprehensive approach for the stable system operation. The feasibility of the analytical result is verified through simulation and experimental tests.

scholarly journals Control System Development for the Three-Ports ANPC Converter

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3967 ◽  
Author(s):  
Silvio Antonio Teston ◽  
Kaio Vinicius Vilerá ◽  
Marcello Mezaroba ◽  
Cassiano Rech
Keyword(s):  
Control System ◽  
Single Phase ◽  
System Development ◽  
Phase 1 ◽  
Storage System ◽  
Low Frequency ◽  
Energy Storage System ◽  
Neutral Point ◽  
Battery Life ◽  
Current Ripple

This paper proposes a control system for the single-phase Three-Ports Active Neutral- Point-Clamped (ANPC-3P) converter, which can inject a sinusoidal current into the grid, balance the neutral point voltage, and regulate the energy storage system (ESS) current with reduced low-frequency ripple. Despite other applications, ANPC-3P inverter can be used in grid-tied renewable generation to allow the simultaneous connection of a photovoltaic (PV) energy source and an ESS to the AC grid. The ESS is connected directly to the inverter circuit without any auxiliary DC-DC converter, but due to the DC bus pulsed power, it can be subjected to low-frequency current ripple. This undesired current ripple is difficult to filter and can lead to shorter battery life. A control system based on well-known controllers is analyzed and designed. Theoretical analysis is validated experimentally using a single-phase 1-kW prototype.

10kV Grid Arc Grounding Over-Voltage Hazards and Countermeasures

2013 ◽  
Vol 392 ◽  
pp. 489-493
Author(s):  
Qing Hao Wang ◽  
Zi Jun Huang ◽  
Zhi Gang Li ◽  
Bo Fang ◽  
Gui Bin Hu
Keyword(s):  
Single Phase ◽  
Power Grid ◽  
Operation Mode ◽  
Scientific Basis ◽  
Neutral Point ◽  
Correct Selection ◽  
Capacitive Current ◽  
Current Test ◽  
Selection Of

Through the analysis of 2 single-phase grounding over voltage accidents caused by capacitive over current in 10 kV power grid in this paper, the causes and damages of arc grounding over voltage are illustrated, and the necessity of capacitive current test and effective methods are pointed out. The test and assessment to the 29 substations capacitor currents provides a scientific basis for the correct selection of the neutral point operation mode, and the strengths and weaknesses of the neutral Point grounding through the arc suppression circle and the mode trends of 10kV grid neutral grounding are demonstrated.

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