A new control strategy for single phase cascaded H bridge multilevel inverter in stationary reference frame with nonlinear loads

This paper investigates the realization of a five-level Flying Capacitor Inverter. After a brief description of general Power Electronic Converters and an introduction to the advantages of Multilevel Inverters over conventional two-level Inverters the main focus is on the five-level Flying Capacitor Inverter. The Flying Capacitor Multilevel Inverter (FCMI) is a Multilevel Inverter (MI) where the capacitor voltage can be balanced using only a control strategy for any number of levels. After a general description of five-level FCMI topology, the simulation and experimental results are presented. The capacitor voltage is stabilized here with various output voltage amplitude values. The simulation and experimental results of five-level FCMI show that the voltage is stabilized on capacitors using the control strategy. A single-phase five-level FCMI model is currently being developed and constructed in the laboratory. Some of the experimental results are available.

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Synchronous Reference Frame Repetitive Control of a Single-Phase Three-Level Dual-Buck Photovoltaic Inverter

Electronics ◽

10.3390/electronics7100226 ◽

2018 ◽

Vol 7 (10) ◽

pp. 226 ◽

Cited By ~ 1

Author(s):

Jung-Yong Lee ◽

Younghoon Cho

Keyword(s):

Reference Frame ◽

Control Strategy ◽

Single Phase ◽

Harmonic Distortion ◽

Current Control ◽

Output Current ◽

Pv Inverter ◽

Synchronous Reference Frame ◽

Conduction Mode ◽

Repetitive Controller

This paper proposes a synchronous reference frame (SRF) control strategy for a single-phase, three-level, dual-buck photovoltaic (PV) inverter. The concept of virtual d-q transformation is adapted to the current control of the inverter, and the repetitive controller is implemented in the SRF. With the proposed control strategy, the memory allocation quantity for the repetitive controller is decreased and the capability of the current reference tracking is maximized. Thus, the proposed method significantly reduces the total harmonic distortion (THD) of the output current in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In addition, the distortion of the output current is mostly composed of odd harmonics. Odd harmonic expressed to the even harmonic in SRF can be calculated using Park’s transformation. Therefore, a repetitive controller can improve dynamics by considering only even harmonic components in SRF rather than including all harmonics. The simulation and the experimental results verify the effectiveness of the proposed control strategy. The proposed method not only reduces the THD of the output current in both the CCM operation and the DCM operation, but also improves the dynamics of the current controller.

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A Stationary Reference Frame Current Control Algorithm for Improvement of Transient Dynamics of a Single Phase Grid Connected Inverter

Electronics ◽

10.3390/electronics9050722 ◽

2020 ◽

Vol 9 (5) ◽

pp. 722 ◽

Cited By ~ 2

Author(s):

Horyeong Jeong ◽

Jae Suk Lee

Keyword(s):

Reference Frame ◽

Disturbance Rejection ◽

Control Algorithm ◽

Single Phase ◽

Current Control ◽

Phase Lag ◽

Phase Current ◽

Disturbance Rejection Control ◽

Stationary Reference Frame ◽

Grid Connected Inverter

This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied to a current controller for implementation of disturbance rejection control (DRC). In the proposed current control algorithm, the disturbance rejection control algorithm is applied to reduce the overcurrent occurring in the single-phase grid-connected inverter when grid faults happen. In this paper, the AC phase current of a single-phase inverter is controlled, instead of the current vector, which is a DC signal. To compensate for the drawbacks of controlling the AC phase current, such as phase lag and steady-state error, command feedforward control is also applied in the proposed control system. The proposed control algorithm is mathematically derived and represented in transfer functions and implemented via simulation and experiment.

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