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In single-phase photovoltaic (PV) systems, power mismatching between input and output terminal leads to power pulsation, seriously affecting maximum power point tracking (MPPT). Paralleling an electrolytic capacitor (e-cap) across PV panel to smooth power pulsation seems to be an unreliable method owing to its short lifetime. Various power decoupling methods used in micro-inverters have been proposed...
This paper presents a selective harmonics reduction for a 3(n+1) shared switch inverter topology utilizing optimal arrangement of the n-modulated signal. Under different modulation indices and operating power frequencies the purpose of the proposed procedure is to select an optimal load connection and/or modulation offsetting based on the desired objective function. Three performance indices are studied...
A new scheme for Direct Torque Control (DTC) of dual inverter fed Induction Motor (IM) with open end stator winding is presented in this paper. This scheme eliminates common mode voltage from the windings there by facilitating both inverters to draw power from a common DC source without circulation of common mode currents though the windings and switches. A major advantage of this DTC scheme is the...
Parallel Neutral-Point Clamped (NPC) inverters are commonly employed in medium voltage high power applications, such as wind energy system, smart transformer, and power conditioners. In literature, it is shown that the Phase Disposition modulation (PD) strategy provides better performance in terms of harmonic profile and current ripple for single NPC application. Therefore, the PD has been commonly...
Grid connected PV systems are the most popular solar electric system on the market today. The most important device in the grid-connected PV system is the inverter. This paper presents a survey on the grid connected PV inverters and the system topologies used for grid connected PV system. The review describes different two level inverter topologies as well as multilevel inverter topologies. Cascaded...
This paper proposes an induction motor drive scheme generating multilevel twenty-four sided voltage space vector structure using single DC source. The topology consists of basic units with DC-source fed main three-level flying-capacitor (FC) inverter cascaded with two low-voltage floating-capacitor fed H-Bridge cells (CHB). The generated space vector structure has six concentric 24-sided polygons...
This paper presents the analysis of harmonic and switching loss for two-level space vector based pulse width modulation (PWM) schemes. The harmonic performance of the inverter is evaluated through weighted voltage total harmonic distortion for different modulation indices. To calculate switching loss, analytical expressions for switching instants are generated by comparing the triangular carrier signal...
Two control strategies, a finite-state predictive torque control and a linear control with space-vector PWM, are developed and experimentally assessed in this paper. Both strategies are used to control a permanent magnet synchronous motor supplied by a three-level neutral-point-clamped inverter. The high complexity of the drive system and the different nature of the control objectives make the development...
Nowadays capacity of the photovoltaic systems in the grid is remarkable and provides a major part of energy in the grid. Therefore, an abruption of these systems from the grid can create a damage to the grid. Unlike in the past that PV systems disconnected from the grid when a voltage drop occurred, nowadays these systems should have Low Voltage Ride-Through (LVRT) capability. The PV system should...
A predictive control scheme for the third-harmonic injection two-stage matrix converter (3TSMC) under unbalanced input voltages is presented. The proposed scheme is designed to predict the future behavior of the third-harmonic injection current and load currents respectively for each valid switching state. The control scheme selects the state that minimizes the error between the predicted currents...
This paper introduces a paralleled three-phase four-leg inverters and the corresponding pulse width modulation (PWM) method for the purpose of reduction the common mode current (CMC) and common mode electromagnetic interference (EMI). Considering the control principle of three-phase four-leg to limit the common mode voltage and the characteristic of paralleled inverters, the simple PWM scheme for...
Transformerless photovoltaic (PV) inverters offer several advantages in terms of weight and cost reduction as well as a higher efficiency compared to the topologies with transformers. However, the removal of transformers results in the establishment of a direct connection between the PV panels and the electrical grid which, consequently, leads to the generation of a leakage current. This current is...
A space vector pulse-width modulation (SVPWM) strategy for a three-level asymmetrical six-phase drive, with a single neutral point, based on vector space decomposition (VSD) approach is presented for the first time in this paper. The selection process, related to the determination of the right switching sequences for the proposed modulation strategy, is discussed in detail. The developed SVPWM strategy...
In this paper, a current control is studied based on D-Σ digital control to improve the grid-connected performance for a three-level T-type inverter. The control principle is analyzed in accordance with the single-phase equivalent circuit of the three-level T-type inverter. The influence of the neutral-point voltage on both output current error and modulation signal is discussed, and the relationship...
This paper proposes the modeling of single phase symmetric flying capacitor multilevel inverter (SFC-MLI) for Static synchronous compensator (STATCOM) application. The proposed topology is composed of cascade-connected five-level SFC modules. The linear current controller with phase shifted and phase disposition pulse-width modulation (PS-PD-PWM) base switching technique has been implemented. To takes...
This paper proposes the pulse width modulation (PWM) technique for the five-phase open-end winding induction motor (FPOEWIM) drive fed from five-phase dual inverter (FPDI) with a single dc source. The selected method gives the advantages of reduced switching losses specifically for induction motor drives working with higher power factors with the elimination of common-mode current (CMC). The method...
High quality voltage and current are required when PV generator is connected to grid utility. To this, multilevel inverters are very desirable to be used as connection interface. To keep the cost of the whole system as low as possible, a cost-effective control device using STM32F4 discovery board is employed to control three-level inverter that can be used in grid-tied PV system. The paper develops...
The multimedia system for e-learning about modulation techniques in three phase voltage controlled inverters is introduced. The multimedia system features for Block commutation, Sine Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) are illustrated. Advantages of proposed multimedia system for e-learning about modulation techniques in three phase voltage inverters are indicated...
A well-known problem of three-level neutral point clamped (NPC) inverter is the voltage imbalance in the dc-link capacitors. This paper proposes the dc-link capacitor voltage balancing method where a common offset voltage is injected. The offset voltage consists of a harmonic voltage and a magnitude difference between the upper and the lower capacitors. Theoretical analysis is provided to balance...
There are two commonly used 3-phase configurations in power grid applications, the 3-phase 3-wire, and 3-phase 4-wire configurations. The 3-phase 4-wire power converter systems is necessary to supply single-phase loads but at the expense of higher output harmonics and losses, as compared to 3-phase 3-wire systems. The neutral inductor is added to reduce the neutral line harmonics and a LCL+ L filter...
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