VOLTAGE SOURCE INVERTER PDF
generates ac output. If the input dc is a voltage source, the inverter is called a voltage source inverter (VSI). One can similarly think of a current source inverter. VOLTAGE SOURCE INVERTER (VSI). INTRODUCTION. This chapter presents speed and torque characteristics of induction motor fed by a new controller. Full bridge Single Phase Voltage Source Inverter. Half Bridge Voltage Source Inverter. Figure shows a circuit topology of a Half-Bridge VSI, where two.
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PDF | Voltage source inverters (VSI) are commonly used in uninterruptible power supplies (UPS) to generate a regulated AC voltage at the. 𝗣𝗗𝗙 | This paper presents a new modification for the most-common, simple, and well-known three-phase voltage source inverter (VSI). Abstract—In this paper, the different types of voltage sourse inverters are studied. The voltage source inverters are the main component of the variable frequency.
One measure of the purity of a sine wave is the total harmonic distortion THD. There are two basic designs for producing household plug-in voltage from a lower-voltage DC source, the first of which uses a switching boost converter to produce a higher-voltage DC and then converts to AC.
The second method converts DC to AC at battery level and uses a line-frequency transformer to create the output voltage.
Square wave output can produce "humming" when connected to audio equipment and is generally unsuitable for sensitive electronics. Sine wave Sine wave[ edit ] A power inverter device which produces a multiple step sinusoidal AC waveform is referred to as a sine wave inverter. To more clearly distinguish the inverters with outputs of much less distortion than the modified sine wave three step inverter designs, the manufacturers often use the phrase pure sine wave inverter.
Power Electronics - Types of Inverters
Almost all consumer grade inverters that are sold as a "pure sine wave inverter" do not produce a smooth sine wave output at all,  just a less choppy output than the square wave two step and modified sine wave three step inverters. However, this is not critical for most electronics as they deal with the output quite well. Where power inverter devices substitute for standard line power, a sine wave output is desirable because many electrical products are engineered to work best with a sine wave AC power source.
The standard electric utility provides a sine wave, typically with minor imperfections but sometimes with significant distortion. Sine wave inverters with more than three steps in the wave output are more complex and have significantly higher cost than a modified sine wave, with only three steps, or square wave one step types of the same power handling. AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, or may produce more audible noise than when running on sinusoidal power.
Modified sine wave[ edit ] Waveform produced by a cigarette lighter 12 volt DC to VAC 60 Hz inverter The modified sine wave output of such an inverter is the sum of two square waves one of which is phase shifted 90 degrees relative to the other.
The result is three level waveform with equal intervals of zero volts; peak positive volts; zero volts; peak negative volts and then zero volts. This sequence is repeated. The resultant wave very roughly resembles the shape of a sine wave. Most inexpensive consumer power inverters produce a modified sine wave rather than a pure sine wave. The waveform in commercially available modified-sine-wave inverters resembles a square wave but with a pause during the polarity reversal.
If the waveform is chosen to have its peak values for half of the cycle time, the peak voltage to RMS voltage ratio is the same as for a sine wave. The DC bus voltage may be actively regulated, or the "on" and "off" times can be modified to maintain the same RMS value output up to the DC bus voltage to compensate for DC bus voltage variations. By changing the pulse width, the harmonic spectrum can be changed. This is slightly lower than for a square wave.
The generated gate pulses are given to each switch in accordance with the developed pattern to obtain the desired output. Harmonic spectrum in the output depends on the width of the pulses and the modulation frequency. Items with a switch-mode power supply operate almost entirely without problems, but if the item has a mains transformer, this can overheat depending on how marginally it is rated.
However, the load may operate less efficiently owing to the harmonics associated with a modified sine wave and produce a humming noise during operation. This also affects the efficiency of the system as a whole, since the manufacturer's nominal conversion efficiency does not account for harmonics.
Therefore, pure sine wave inverters may provide significantly higher efficiency than modified sine wave inverters.
However, they may be quite noisy. A series LC filter tuned to the fundamental frequency may help. This signal then goes through step-up transformers generally many smaller transformers are placed in parallel to reduce the overall size of the inverter to produce a higher voltage signal.
The output of the step-up transformers then gets filtered by capacitors to produce a high voltage DC supply. More complex inverters use more than two voltages to form a multiple-stepped approximation to a sine wave. These can further reduce voltage and current harmonics and THD compared to an inverter using only alternating positive and negative pulses; but such inverters require additional switching components, increasing cost.
Output frequency[ edit ] The AC output frequency of a power inverter device is usually the same as standard power line frequency, 50 or 60 hertz If the output of the device or circuit is to be further conditioned for example stepped up then the frequency may be much higher for good transformer efficiency.
Output voltage[ edit ] The AC output voltage of a power inverter is often regulated to be the same as the grid line voltage, typically or VAC at the distribution level, even when there are changes in the load that the inverter is driving. This allows the inverter to power numerous devices designed for standard line power. Some inverters also allow selectable or continuously variable output voltages.
Output power[ edit ] A power inverter will often have an overall power rating expressed in watts or kilowatts.
This describes the power that will be available to the device the inverter is driving and, indirectly, the power that will be needed from the DC source. Smaller popular consumer and commercial devices designed to mimic line power typically range from to watts.
Not all inverter applications are solely or primarily concerned with power delivery; in some cases the frequency and or waveform properties are used by the follow-on circuit or device.
Batteries[ edit ] The runtime of an inverter powered by batteries is dependent on the battery power and the amount of power being drawn from the inverter at a given time. As the amount of equipment using the inverter increases, the runtime will decrease.
In order to prolong the runtime of an inverter, additional batteries can be added to the inverter. In a series configuration, if a single battery dies, the other batteries will not be able to power the load. Parallel configuration If the goal is to increase capacity and prolong the runtime of the inverter, batteries can be connected in parallel.
This increases the overall ampere-hour Ah rating of the battery set. If a single battery is discharged though, the other batteries will then discharge through it.
This can lead to rapid discharge of the entire pack, or even an over-current and possible fire. To avoid this, large paralleled batteries may be connected via diodes or intelligent monitoring with automatic switching to isolate an under-voltage battery from the others.
The unit shown provides up to 1. An inverter converts the DC electricity from sources such as batteries or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.
Uninterruptible power supplies[ edit ] An uninterruptible power supply UPS uses batteries and an inverter to supply AC power when mains power is not available. When mains power is restored, a rectifier supplies DC power to recharge the batteries. Electric motor speed control[ edit ] Inverter circuits designed to produce a variable output voltage range are often used within motor speed controllers.
The DC power for the inverter section can be derived from a normal AC wall outlet or some other source. The figure below shows a voltage source inverter employing transistor.
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It is operated as a stepped-wave inverter or a pulse width modulation. The waveform of the line voltage is shown in the figure below. The frequency of the inverter is varied by varying T, and the output voltage of the inverter is varied by varying DC input voltage.
When the supply is AC, then the DC input voltage is obtained by connecting the controlled rectifier between the AC supply and inverter shown in the figure below. The capacitor C filter out the harmonics in DC link voltage. The main drawback of the VSI induction motor drive is the large harmonics of the low frequency in the output voltage. The harmonics increases the loss in the motor and cause the jerky motion of the rotor at low speed. When the operation of the motor is shifted from motoring to braking switch SW is opened.
The energy flowing through the DC link charges the capacitors and its voltage rises. When the voltage crosses the set value, switch S is closed, connecting the resistance across the link.
The energy which is stored in the capacitor flows into the resistance and reduces the DC link voltage. When it falls to its nominal value S is opened.
Thus the closing and opening of the switch depends on the DC link voltage, and the generated energy is dissipated in the resistance gives dynamic braking.Cortes, R. CrossRef Google Scholar  S.
Since , he has been a Ph. Karimi, and X. More complex inverters use more than two voltages to form a multiple-stepped approximation to a sine wave. Miscellaneous[ edit ] Typical applications for power inverters include: Portable consumer devices that allow the user to connect a battery , or set of batteries, to the device to produce AC power to run various electrical items such as lights, televisions, kitchen appliances, and power tools.
Two‐Level Voltage Source Inverter
His research interests are in the areas of signal processing, motor fault detection, network system control, time-delay systems, and neural networks.
Moinoddin, H. Broeck, H. Al-Barakati, and H.
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