Ibrahim Babaei

Bio: Ibrahim Babaei is an academic researcher from University of Tabriz. The author has contributed to research in topics: Inverter & Three-phase. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Improved quasi-Z-source based three-phase three-level neutral point clamped inverter

Abstract: In this paper, a new three-phase three-level neutral point clamped (NPC) inverter based on improved Quasi-Z-source (QZS) network is proposed. The proposed QZS inverter in comparison with conventional Z-source and Quasi-Z-source inverters has higher boost factor under smaller duty cycle. Moreover, smaller duty cycle, lower voltage stress, less total harmonic distortion (THD), and continuous input current are some advantages of the proposed inverter. In this paper, different combinations of allowed switching states with their control signals for proposed inverter are presented by using SPWM control method. The simulations results in PSCAD software are performed to prove the performance of the proposed topology.

A Three-Level DC-Link Quasi-Switch Boost T-Type Inverter with Voltage Stress Reduction

Abstract: In recent years, the three-level T-Type inverter has been considered the best choice for many low and medium power applications. Nevertheless, this topology is known as a buck converter. Therefore, in this paper, a new topology incorporating the dc-link type quasi-switched boost network with the traditional three-level T-type inverter is proposed to overcome the limit of traditional three-level T-Type inverter. The space vector pulse width modulation scheme is considered to control this topology, which provides some benefits such as enhancing modulation index and reducing the magnitude of common-mode voltage. For this scheme, the zero, medium, and large vectors are utilized to generate the output voltage. The shoot-through state which is adopted by turning on all power switches of inverter leg is inserted into zero vector to boost the dc-link voltage. As a result, there is no distortion at the output waveform. The control signal of intermediate network power switches is also detailed to improve the boost factor and voltage gain. As a result, the voltage stress on power devices like capacitors, diodes, and switches is decreased significantly. To demonstrate the outstanding of proposed structure and its control strategy, some comparisons between the proposed method and other ones are performed. Simulation and experimental prototype results are conducted to verify the accuracy of the theory and effectiveness of the inverter.

Single-Phase Three-Level Neutral-Point-Clamped Inverter Based on Modified Z-Source Network With Reduced Voltage Stress on Capacitors

Abstract: This article presents a new topology for single-phase three-level neutral-point-clamped inverter. The proposed topology uses a modified Z-source network that for the same boost factor has lower voltage stress across the capacitors in comparison to the traditional Z-source inverters. Therefore, this topology leads to a lower capacitor size as well as decreased cost. In this article, the different operating modes of the proposed inverter in steady-state are analyzed. Moreover, voltage stress across capacitors, voltage ripple of capacitors, and current ripple of inductors are calculated using dc and $2\omega $ components analyses. Then, the proper values of inductors and capacitors are designed. The proposed inverter is compared with the traditional inverter topologies to show its advantages and disadvantages. The effectiveness of the proposed inverter is tested by using a laboratory-built prototype and simulation under MATLAB/Simulink environment.

PWM Control Methods Based on Mathematical Equations for Z-Source Inverters

Abstract: In power converters, the total harmonic distortion (THD) can be decreased by using two strategies which are filtering and controlling methods. The filtering strategy is indeed costly because of using hardware devices (such as capacitor and inductor). A suitable strategy to control the modern power converters without using the hardware devices is the pulse width modulation (PWM) technique. In this paper, three new PWM control methods based on mathematical equations for various Z-source inverters (ZSIs) are proposed. Controlling the duty cycles of switches is the basic idea of these methods to control the output voltage. The proposed control methods are analyzed under the circumstances of constant input and balanced output voltage (CIBOV) and ripple input and balanced output voltage (RIBOV). The advantages of proposed methods are control of voltage, current and harmonic distortion. Other advantages of these methods are lower value for THD and elimination of low-order harmonics. The correctness operation of the proposed PWM techniques is proved by using the simulation results.

Design and Control of Three-phase Quasi-Z-Source Based Hybrid 2/3 Level Inverter

Abstract: Hybrid 2/3 level inverter is a combination of three-level diode clamped inverter and conventional two-level inverter. This structure has the advantages of both two-level and three-level structures. Also, the number of switches is less than three level diode clamped inverter. In this paper, a modified structure for a hybrid 2/3 level inverter, which is based on quasi-Z-source network, is investigated. This structure improves the performance of the 2/3 level inverter and develops the voltage boost capability of the structure. Increasing the output voltage can be achieved by selecting the appropriate short-circuit interval in quasi-Z-source network. In addition, short-circuit intervals in quasi-Z-source networks allow the inverter to operate without any dead time, which results in higher quality for output AC voltage. A modified switching method is presented for the proposed inverter and the related calculations are performed. Also, a simple control scheme is proposed to balance the neutral-point of the structure and to compensate the voltage imbalance of the Quasi network’s capacitors. The proposed structure can be used to connect different distributed generation sources to an islanded load or to a low voltage grid. Simulations are carried out in MATLAB/Simulink environment and results depict suitable performance of proposed inverter.