Modified Predictive Control Method of Three-Level Simplified Neutral Point Clamped Inverter for Common-Mode Voltage Reduction and Neutral-Point Voltage Balance

Fei Wang,Xiangrong Tong,Zhijun Li

doi:10.1109/access.2019.2936611

Fei Wang, Xiangrong Tong + Show 1 more

Open Access

https://doi.org/10.1109/access.2019.2936611

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Journal: IEEE Access	Publication Date: Jan 1, 2019
Citations: 13	License type: CC BY 4.0

Affiliation: Hebei University of Technology, Yantai University

Abstract

Three-level simplified neutral point clamped (NPC) inverters are studied due to lower harmonics and fewer switching devices. Nevertheless, this topology needs to obtain neutral point (NP) voltage balance through either control or modulation methods. For the operation of photovoltaic application, the common-mode voltage (CMV) is needed to meet the requirements of leakage current. To address these issues, a modified predictive control method via two-layer vector selection criteria is proposed. In the first layer, the candidate switching vectors for the CMV reduction are selected. In the second layer, the P-type or N-type small vectors are selected for NP voltage balance. Then, the control method selects the optimized switching vector from the cost function consisting of the number of switching and the current, which can obtain the better performance depending on the power rating. Simulation and experimental verification results show that the modified predictive control method can reduce CMV and balance NP voltage both steady-state and transient process.

Highlights

Three-phase inverters are extensively used in various types of industrial applications, for example static var generator, photovoltaic (PV) and active power filter [1]–[4]
common-mode voltage (CMV) reduction and neutral point (NP) voltage balance are required in practice
A modified model predictive control strategy is proposed to reduce CMV and balance NP voltage based on discrete mathematical model

Summary

INTRODUCTION

Three-phase inverters are extensively used in various types of industrial applications, for example static var generator, photovoltaic (PV) and active power filter [1]–[4]. It is observed that the absence of medium vector in three-level simplified NPC inverter make the above CBPWM and SVM cannot be used directly. To address this problem, a model predictive control method is proposed for three-level sparse NPC. In [19]–[21], CBPWM and SVM method were proposed to reduce CMV in multilevel inverters. In [25], a model predictive control method is proposed to reduce common-mode voltage and balance the neutral-point voltage in three-level T-type inverter. To reduce CMV and NP voltage at the same time, an improved model predictive control method with twolayer vector selection criteria is proposed. The optimized switching vector is selected from the cost function consisting of the number of switching and current, which can obtain better performance depending on the power rating

THE MODEL OF THREE-LEVEL SIMPLIFIED

SIMULATION AND EXPERIMENTAL RESULTS

CONCLUSION