Advantages And Disadvantages Of Multilevel Inverters

Modelling of the series transformer, VSC and LC filter is presented in this section. A time-varying threephase

The impact of the proposed sequences has been simulated for 0.4 modulation index with a 0.5 lagging power factor load (power factor angle 60°). The simulation setup consists of the following software: 1) MATLAB/Simulink – used to implement the modulation strategies and switching sequences, and 2) PSIM – used to simulate the T-NPC inverter running with an R-L load and to provide conduction and switching losses of each switch. The inverter switching pulses were generated within Simulink and were fed to PSIM through sim-coupler module which provides a link between PSIM and simulink for the purpose of co-simulation [29].

The innovative inverter technology produces safe, smooth power, protecting your sensitive electronics (computers, smartphones, etc.) from damage.

Space Vector PWM (SVPWM) refers to a special switching sequence of the upper three power transistors of a three-phase power inverter. It has been shown to generate less harmonic distortion in the output voltages and or currents applied to the phases of an AC motor and to provide more efficient use of supply voltage compared with sinusoidal modulation technique. The biggest difference from other PWM methods is that the SVPWM uses a vector as a reference. This gives the advantage of a better overview of the system.

Moreover, input node voltages and currents can be referred to the input terminal voltages of the inverter with reference to ground point and the corresponding currents from each node of the capacitors to the inverter respectively. As an example, input node (dc) currents by I_1,I_2 etc., and input node (dc) voltages are designed by V_1,V_2, etc as shown in Figure 1a. V_a,V_b and V_c are the root mean square (rms) values of line load voltages; I_a,I_b and I_c are the rms values of the line load currents. Figure 3.1 a shows the schematic of a pole in a multilevel inverter where V_a indicates an output phase voltage that can predicted at any voltage level depending on the selection of node (dc) voltage V_1,V_2 etc. By connecting switch to one node at a time, one can easily obtain the desired output. Figure 3.2 shows the typical output voltage of a five-level inverter. The structure of multilevel inverter must (1) have less switching devices as far as possible, (2) have capability of withstanding at very high input voltage for high-power applications, and (3) have lower switching frequency for each switching

Keywords: — Mathematical model of photovoltaic cell; photovoltaic module; array; boost converter; mppt algorithm; pwm; single phase inverter; three phase inverter; MATLAB/simulink; gate pulse using 555 timer; voltage doubler circuit in hardware.

AC electrical energy in grid interactive PV system. To achieve direct medium-voltage which is present at grid without using bulky medium-voltage transformer ,cascaded multilevel converters are attracting more and

Feed forward control is a reliable for rejecting fast and dynamic voltage disturbances in the phase grid. Mainly in this scheme implemented in phase voltages of the Wyes connected configuration. Under this unbalanced and distorted grid conditions, the online conversion of line - to - line values into the phase value is unworkable. In order to an exploit full advantages of feed forward controller is a most appropriate modulator is needed. In this article the feed forward of grid line-to-line voltages is used in phase voltages. The introduced feed forward method is implemented in Implicit Zero Sequence Discontinuous Pulse Width Modulation (IZDPWM) technique that is compatible for grid connected inverters. Regarding in the IZDPWM grid topologies distorted the harmonics of the grid voltages. Hence, a sinusoidal current is injected to the grid. Moreover, the measuring grid line-to-line voltages two sensors are required; hence an overall system costs is reduced and control system reliability is increased. The time-domain simulations in MATLAB/Simulink and experimental results from a Hardware based laboratory prototypes are in good agreements,

2Control & Mechatronics Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor Bahru, Malaysia

Measuring the power quality it requires the network system voltage within their limits, as the non linear loads increasing .Effects of Harmonic on power quality and the efficiency. In power system , harmonics are the multiples frequencies . when we apply pure sinusoidal wave form of

Inverters are able to supply controlled voltage and frequency depending on the control algorithms [3]. The characteristics of inverters are significantly different from the conventional generators; therefore, specific control algorithms are required for a stable microgrid operation [4, 5].

In a research article [9], the frequency response characteristics of the system can be altered when the harmonic distortion levels are not within the acceptable limits through changing sizes or locations of the capacitor, by changing source characteristics, or by design a harmonic filter. Filters are the most common solution as it can provide reactive power support at the fundamental frequency and a low impedance path for one or more harmonic current components to flow. The filter elements must be specifically designed to withstand the harmonic components along with the fundamental frequency voltages and currents. Common method for filter design is by utilizing one single-tuned shunt filter first, designed for the lowest generated harmonic (typically 5th) and it is advisable to use capacitors with a higher voltage rating than the system. Determine the voltage distortion level at the bus. The commonly applied limit of 5% (total harmonic distortion – THD) was presented in IEEE Standard 519-1981. If required, determine if the harmonic current levels meet IEEE Standard 519-1992. If not, there may be a need for multiple filters (i.e., 5th and 7th). Vary the filter elements according to the specified tolerances and check its effectiveness. Lastly, by checking the frequency response characteristic to verify that the newly created parallel resonance is not close to a generated harmonic frequency (i.e., the 7th harmonic filter may create a new 5th harmonic resonance).

The choice of right type of converters for the different requirement in specific application has great influence on the optimum performance of the photovoltaic system. In last two decades, enormous developments have been taken place in the area of solar PV power generation. A large number of research publications in these areas have led to this persuasion of a critical review of the available literature. In particular, many inverter topologies have been introduced to incorporate several unique features, such as a) intrinsic boost capabilities, b) isolation, c) high efficiency, d) good power decoupling, e) dual grounding function, f) single stage solar power conversion capabilities, g) compact design and h) good power quality, for both

Power electronic converters, especially DC/AC inverters have been extending their range of use in industrial application because they provide better system efficiency, reduced energy consumption and improved quality of power. The output voltage of inverter could be fixed or variable at a fixed or variable frequency and output waveforms are therefore made up of discrete values, producing fast transition rather than smooth ones [2]. The ability to

Generally the power amplifier operated in 2 modes standby and output modes. To increase the efficiency lowest standby mode must be used. But the sudden jump from standby to output mode might distort the signals. So the technologies stay at high standby level wasting a lot of electricity. This company now proposes an idea of using a fast electronic gearbox which can choose among different voltages that can be sent to the transistor and they claim it is capable of doing 20 million times per second. This technology is called as “Asymmetric Multilevel out phasing”