DC-Link Capacitor Voltage Imbalance Compensation Method Based Injecting Harmonic Voltage for Cascaded Multi-Module Neutral Point Clamped Inverter

In a three-level (NPC) converter, the voltage imbalance problem in the DC-link capacitors is major issue. This paper proposes the DC-link capacitor voltage imbalance compensation method, where a common offset voltage is injected for a multi-module NPC inverter. The offset voltage consists of a harmonic voltage and a voltage difference between the upper and lower capacitors. The proposed method does not require any hardware modification, so that it is easily implemented. In order to show the effectiveness of the proposed balancing method, theoretical analysis is provided to balance the voltages, and both the simulations and the experiments were carried out to show that the voltage difference of the DC-link was decreased by the proposed method.

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A Harmonic Voltage Injection Based DC-Link Imbalance Compensation Technique for Single-Phase Three-Level Neutral-Point-Clamped (NPC) Inverters

Energies ◽

10.3390/en11071886 ◽

2018 ◽

Vol 11 (7) ◽

pp. 1886 ◽

Cited By ~ 3

Author(s):

Kyoung-Pil Kang ◽

Younghoon Cho ◽

Myung-Hyo Ryu ◽

Ju-Won Baek

Keyword(s):

Second Order ◽

Neutral Point ◽

Voltage Difference ◽

Imbalance Problem ◽

Offset Voltage ◽

Half Wave ◽

Unbalanced Voltage ◽

Compensation Technique ◽

Harmonic Voltage ◽

Harmonic Components

In three-level neutral-point-clamped (NPC) inverters, the voltage imbalance problem between the upper and lower dc-link capacitors is one of the major concerns. This paper proposed a dc-link capacitor voltage balancing method where a common offset voltage was injected. The offset voltage consists of harmonic components and a voltage difference between the upper and the lower capacitors. Here, both the second-order harmonics and the half-wave of the second-order component were injected to compensate for the unbalanced voltage between the capacitors. In order to show the effectiveness of the proposed voltage injection, the theoretical analyses, simulations, and experimental results are provided. Since the proposed method does not require any hardware modifications, it can be easily adapted. Both the simulations and the experiments validated that the voltage difference of the dc-link could be effectively reduced with the proposed method.

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Three-Phase Three-Level Neutral Point Clamped Rectifier with Predictive Control Method without Employing Weighting Factor

Applied Sciences ◽

10.3390/app10155149 ◽

2020 ◽

Vol 10 (15) ◽

pp. 5149 ◽

Cited By ~ 2

Author(s):

Eun-Su Jun ◽

Minh Hoang Nguyen ◽

Sangshin Kwak

Keyword(s):

Predictive Control ◽

Control Method ◽

Weighting Factor ◽

Neutral Point ◽

Control Methods ◽

Offset Voltage ◽

Three Phase ◽

Sinusoidal Input ◽

Capacitor Voltage ◽

Voltage Balance

A predictive control method using injected offset voltage to achieve neutral point (NP) voltage balance of three-phase three-level neutral point clamped (NP) rectifiers, without employing a weighting factor, is proposed in this study. One of the biggest problems with the three-level NP rectifiers is the dc link capacitor voltage imbalance. Therefore, it is necessary to maintain the balance of the NP voltage in addition to synthesize the three-phase sinusoidal input current by control methods. Conventional predictive control methods for the NP rectifiers have used a weighting factor in a cost function that determines the control ratio of the input currents and the capacitor voltage balance. As a result, it is burdensome to empirically redesign the weighting factor when the rectifiers’ parameter values and control conditions change. Unlike the conventional methods, the proposed approach without the weighting factor can significantly eliminate differences between two DC capacitor voltages by utilizing an offset voltage, which is generated by using the difference between the upper and lower capacitor voltages. Consequently, the proposed approach using the offset voltage injection can control the input currents and retain the balance of NP voltage. Simulation and experiments are presented to verify the correctness of the NP voltage balancing of the proposed control method.

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Simulation and Research of Dynamic Voltage Detection and Regulator Based on MATLAB

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.536-537.1527 ◽

2014 ◽

Vol 536-537 ◽

pp. 1527-1531

Author(s):

Ya Feng Li ◽

Zi Wei Zheng

Keyword(s):

Theoretical Analysis ◽

Reactive Power ◽

Voltage Regulator ◽

New Approach ◽

Dynamic Voltage ◽

Harmonic Voltage ◽

Simulation Results ◽

Harmonic Source ◽

Detecting Method ◽

Dynamic Voltage Regulator

The Series Dynamic Voltage Regulator can compensate the harmonics distortion caused by voltage type harmonic source This paper presents a new approach of detecting harmonic voltage in dq0 coordinates, based on the generalized instantaneous reactive power ,and used in the series dynamic voltage regulator successfully. It is demonstrated by theoretical analysis and simulation results that the proposed detecting method of harmonic voltage is correct and valid.

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A new seven level boost-type ANPC inverter topology for photovoltaic applications

Scientific Reports ◽

10.1038/s41598-021-01669-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jagabar Sathik M. ◽

Dhafer J. Almakhles

Keyword(s):

Power Loss ◽

Output Voltage ◽

Detailed Comparison ◽

Input Voltage ◽

Neutral Point ◽

Type Structure ◽

Photovoltaic Applications ◽

Capacitor Voltage ◽

Floating Capacitor ◽

Inverter Topology

AbstractDeveloping of new photovoltaic inverter topologies is received more attention in the last few years. In particular, designing an active neutral-point-clamping inverter type structure is quite popular for PV applications. The output voltage is always half of the input voltage (vin), which further increases the voltage rating of dc-link capacitors in the conventional three-level ANPC. To rectify the above problem and increase the output voltage by reducing dc-link capacitors voltage rating, a new boost type seven-level ANPC inverter topology is proposed. The proposed topology consists of seven switches and one floating capacitor. The floating capacitor voltage is self-balanced, and the output voltage is 1.5 times higher than the input voltage. A detailed comparison for some power components, power loss and cost with other existing topologies are presented. Further, the proposed topology is validated in a prototype hardware setup for different load values.

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