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An efficient modulation stage is required for power conversion to achieve a good performance fulfilling the requirements of output filtering. On a high competitive market, the ability to adjust output harmonic content beforehand is required to adapt to a wide range of operating conditions. For this purpose, selective harmonic mitigation (SHM) is a very attractive solution for high-power applications...
This paper proposes a novel discontinuous PWM (DPWM) in order to reduce dc-link current harmonics of a voltage source inverter (VSI) over wide load-power-factor range. This modulation method, which requires only one carrier, contributes to a lifetime extension of smoothing capacitors in a motor drive system. Furthermore, by realizing this modulation method with only one carrier, a high cost hardware...
The use of converters to feed motors instead of the direct-on-line supply has increased the need to understand the behaviour of the induction machine in different operating points. The additional losses in frequency converter fed machines are caused by the harmonic content of a PWM voltage excitation. This paper investigates closely the harmonic contents of stator supply voltage and current. Most...
This paper represents the Hardware implementation of three phase three level inverter based DSTATCOM to reduce the THD. Inverter based DSTATCOM system using mc3phac IC. In this project mc3phac IC is used to generate PWM pulses with alternate phases these PWM signals are used to fire the IGBT. The system consists of mc3phac IC, IR2110 IC (IGBT drive IC), two voltage regulators (LM7805, LM7812). In...
This paper focuses on the detailed analysis of STATCOM using direct current control method (DCC). This control is strongly recommended for harmonic elimination and reactive power control in the electric transmission system. In direct control method instantaneous value of system current is used for feedback control to achieve fast response. Compared to direct control method, indirect control method...
The problem of designing a zero mean two-level switched periodic waveform with a prescribed harmonic content is considered. A solution is obtained by posing it as a linear programming problem, with the DC bus utilization (ratio of the total power in the prescribed harmonic content to the square of the DC bus voltage) as the cost function and the prescribed harmonic content as linear constraints. The...
Selective Harmonic Elimination (SHE) is an established technique to eliminate unwanted harmonics that causes aliasing effect in communication systems and affects power quality in electrical systems. In this paper, an analytical approach for SHE is proposed for harmonic elimination in a multilevel inverter. Traditionally, numerical methods like Newton Raphson Algorithm are opted to solve the transcendental...
This paper presents the generalized solutions for nonlinear equations of pulse-width-modulation (PWM) switching technique in the cascaded multicell multilevel converters which are modulated under the selective harmonic elimination (SHE) method. The provided solutions are used to explore the total harmonic distortion (THD) of line-to-line voltages in three-phase cascaded multilevel converters. First,...
A new 3-phase current controlled PFC rectifier has been proposed in this paper. Phase difference in between input voltage and current is minimized using an a-periodic control signal generated using input current, phase angle of input voltage, and output voltage. A 1V (P-P) 5KHz triangular wave is used here to generate PWM signal. Simple PID controllers have been added with the controller of the rectifier...
This paper proposes a novel and simple harmonics compensation strategy that can control the fundamental reactive current in the previously proposed smart charger (SC) for electric vehicles (EVs) in single-phase three-wire distribution feeders (SPTWDFs). The proposed harmonics compensation strategy uses only constant dc-capacitor voltage control (CDCVC), which is typically used in grid-connected pulse-width...
In order to avoid the use of an additional circuit to balance the six capacitor voltages of the seven level NPC inverter, redundant states are exploited. The study is so complex because of the huge number of vectors. 720 cases are studied using the selective harmonics elimination PWM instead of space vector PWM. The proposed algorithm is validated in the case of inductive AC load.
This work presents the extended capabilities of a single-phase Pulse Width Modulation (PWM) rectifier to achieve a unity power factor (PF) in the Point of Common Coupling (PCC). It can act as a dynamic var compensator, fixed var compensator and Active Power Filter (APF). To accomplish such tasks a control scheme based in two cascaded loops is used. The outer loop regulates the dc bus voltage and provides...
In recent years, the use of LED street lights instead of sodium and mercury vapor lights is increased in the distribution networks. The high efficiency and reliability, long life, non-emission of infrared and ultraviolet beams, functioning at very low AC and DC voltage, low heat generation, the application at temperatures from +85 to −40 degrees, are the advantages of these lights. The power electronic...
One of the basic problems in power conversion is the harmonic content at output level. Generally harmonics can be categorized as current and voltage harmonics. Harmonics can be minimized either by increasing the number of voltage levels or by using appropriate modulation techniques. In this paper both mechanisms are proposed. The proposed inverter is 7-level Cascaded Multilevel Inverter (CMLI). As...
In this paper, a comparative analysis of with and without injecting the harmonics in switching techniques for multilevel inverter was carried out. The multilevel inverter are said to be the power converter systems where the by controlling the power semiconductor sources properly a controlled multistep voltage waveform will generate. The first approach on multilevel inverter is carried out in Simulink...
AC-AC power conversion has become mandate for modern AC loads due to their standardized supply specifications and unavoidable options of being fed with common AC supply. This paper describes a comprehensive comparison of two competent AC-AC power conversion systems viz. diode bridge front end rectifier-DC link (capacitor)-pulse width modulated voltage source inverter (PWM-VSI) and matrix converter...
Cascaded multicell converter is proved to be an effective solution for medium voltage high power drives. Three-phase diode bridge rectifiers with complex transformer configuration are normally used in this converter, which do not have regenerative capability. Three-phase or single-phase pulsewidth-modulated (PWM) rectifiers are used at the front end to achieve regenerative capability and input power...
This paper proposes a multilevel shunt active power filter (SAPF) to deal with either harmonic currents compensation or reactive power compensation. Such a device can reduce the harmonic distortion at the grid currents provided by non-linear loads located in stiff systems. The proposed SAPF is based on three-phase bridge (TPB) converters connected to cascaded single-phase transformers. The transformers...
In the article is devoted to electromagnetic compatibility (EMC) analysis of 18-pulse AC-DC circuit consisting of three level active front end (AFE) rectifiers based on a pulse width modulation selective harmonic elimination (PWMSHE) method with three switching angles for quarter-period. 18-pulse AC-DC circuit is made as a parallel connection of three power transformers which have the secondary winding...
The well known Selective Harmonic Elimination pulse width modulation (SHE-PWM) is widely used by medium voltage drive applications due its symmetry and control of the low order harmonics that affect output torque, even with low switching frequency. However, the complete harmonic elimination limits the maximum output voltage available, a critical problem for applications where the dc bus voltage level...
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