12-11-2012, 05:12 PM
Advancements In Inverter Technology For Industrial Applications
[attachment=39137]
Inverter is simply an electronic device that converts low voltage DC battery power 230 volts AC (Alternating Current) electrical power. They are used in applications ranging from microwaves laptops to satellite systems X-Ray machines etc.
Most industrial applications require high frequency high voltage power supply. These increased power requirements have lead to significant development in inverted technology.
Significant improvements have been made to the traditional pulse width modulations (PWM) Inverters to make power distribution system more efficient and more suitable to reactive power (var) compensation and harmonic filtering.
This includes using multilevel inverters, zero current switching and other power switching devises. Space application involves high power (hundreds of kilowatts to megawatts) systems. Large power conditioning mass reductions are required to enable this megawatt power system.
Therefore inverter design for space applications represents the state - of - the- art in power conditioning technology. Different features such as design parameters, output a characteristics, switching components etc of these inverters used in space application are discussed in the II part of the paper
1.INTRODUCTION
Inverter (electrical)
An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.
Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.
There are two main types of inverter. The output of a modified sine wave inverter is similar to a square wave output except that the output goes to zero volts for a time before switching positive or negative. It is simple and low cost (~$0.10USD/Watt) and is compatible with most electronic devices, except for sensitive or specialized equipment, for example certain laser printers. A pure sine wave inverter produces a nearly perfect sine wave output (<3% total harmonic distortion) that is essentially the same as utility-supplied grid power. Thus it is compatible with all AC electronic devices. This is the type used in grid-tie inverters. Its design is more complex, and costs 5 or 10 times more per unit power (~$0.50 to $1.00USD/Watt). [1] The electrical inverter is a high-power electronic oscillator. It is so named because early mechanical AC to DC converters were made to work in reverse, and thus were "inverted", to convert DC to AC.
The inverter performs the opposite function of a rectifier.
1.1History
Early inverters
From the late nineteenth century through the middle of the twentieth century, DC-to-AC power conversion was accomplished using rotary converters or motor-generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits. The most widely used type of tube was the thyratron.
The origins of electromechanical inverters explain the source of the term inverter. Early AC-to-DC converters used an induction or synchronous AC motor direct-connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame. The result with either is AC-in, DC-out. With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectified AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC. Hence an inverter is an inverted converter.[6][7]
Controlled rectifier inverters
Since early transistors were not available with sufficient voltage and current ratings for most inverter applications, it was the 1957 introduction of the thyristor or silicon-controlled rectifier (SCR) that initiated the transition to solid state inverter circuits.
1.2 Advanced designs
H-bridge inverter circuit with transistor switches and antiparallel diodes
There are many different power circuit topologies and control strategies used in inverter designs. Different design approaches address various issues that may be more or less important depending on the way that the inverter is intended to be used.
1.3How Does a Power Inverter Work? Power Inverters for Cars
To those of us who think AC/DC is just a band, it is helpful to know what that means in terms of power. If you licked your fingers and touched them to a car battery's terminal, you will be experiencing DC, or direct current, power. This is the direct power that is housed in batteries and generators. When you plug your laptop cord into the wall outlet in your home, you are tapping into AC, or alternating current, power. Before direct current power can be used in our electrical devices, an alternator needs to convert the power. In the US, our electrical appliances require 110 AC power (if you have gone abroad, you know that sometimes you need to have a power converter because other countries often use other electrical voltage). A power inverter turns DC power into AC power. So if you have a battery or generator, you can run any electrical appliance. If a storm knocks your power out, you can power a space heater, hot plate, radio, or other necessities. When camping, you can bring all the comforts of home. On long trips in the car, you can plug in your laptop or cell phone to charge. It really is a very versatile and useful device to have.
AC/DC Power Inverter, Car Power Inverter, AC Power Inverter - So Many Choices, So Little Time
So you're at Home Depot wandering around the power inverter aisle. What now? Check the number of outlets the AC power inverter provides. Many have one to three outlets. Do you need a car power inverter or one that is more permanent? Again, think about what you will likely be powering. Before you head out to buy an AC/DC power inverter, it is important to know specifically what type of inverter you need. For instance, you can buy a $30 power inverter from Home Depot, a $450 solar power inverter, or a $2,000 industrial-grade model. You can buy one for your solar panels to increase energy efficiency or one for your RV for use on vacation. The first question is, "What do I need this for?" A close second is, "How much can I spend?" Keep these two factors in mind as you are shopping.
Related to the first question is the type of product you are going to be using the inverter for most often. For instance, if you will need to run oxygen concentrators, fax machines, electric shavers, garage door openers, and high voltage cordless tool chargers, you will need a true-sine inverter. These produce power that is equal - or better - to that from the power grid. For virtually every other electrical appliance, a modified-sine inverter is sufficient. The power is not identical to that which comes from the grid. Instead of a smooth sine wave, it produces one that is choppy. These AC power inverters are perfectly capable of running everything from televisions to computers.
Also consider where you are going to use the inverter. If you want one that will plug into your vehicle cigarette lighter, you should use an inverter that is rated under 300 watts. If the 12-volt lighter has to draw more power than that, it will strain and eventually blow. But 12 volts is enough to power household appliances, computers, and TVs smaller than 27 inches. 600 watt inverters can also be used with 12-volt sources. They can power larger TV, household appliances, bread machines, and 5 amp tools. The next step up for large appliances, larger power tools, microwaves, toasters, and hairdryers requires a 1750 watt appliance. 3000 watts of power can handle nearly all household appliances and office equipment. The wattage you need will depend on the amps needed to run your device; generally power inverters are divided into under 300, 300, 600, 1800, and 3000 and above watts generated. To convert the amps your device takes to watts, simply take the amp number and multiply it by 120; that is your watt
2.Solar inverter
A Solar inverter or PV inverter is a type of electrical inverter that is made to change the direct current (DC) electricity from a photovoltaic array into alternating current (AC) for use with home appliances and possibly a utility grid.
A PV inverter installed in an attic
Solar inverters may be classified into three broad types:
• Stand-alone inverters, used in isolated systems where the inverter draws its DC energy from batteries charged by photovoltaic arrays and/or other sources, such as wind turbines, hydro turbines, or engine generators. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from an AC source, when available. Normally these do not interface in any way with the utility grid, and as such, are not required to have anti-islanding protection.
• Grid tie inverters, which match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages.
• Battery backup inverters. These are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid. These inverters are capable of supplying AC energy to selected loads during a utility outage, and are required to have anti-islanding protection
• Solar inverters use special procedures to deal with the PV array, including maximum power point tracking and anti-islanding protection.
Anti-islanding protection
Normally, grid-tied inverters will shut off if they do not detect the presence of the utility grid. If, however, there are load circuits in the electrical system that happen to resonate at the frequency of the utility grid, the inverter may be fooled into thinking that the grid is still active even after it had been shut down. This is called islanding.
An inverter designed for grid-tie operation will have anti-islanding protection built in; it will inject small pulses that are slightly out of phase with the AC electrical system in order to cancel any stray resonances that may be present when the grid shuts down.
Since 1999, the standard for anti-islanding protection in the United States has been UL 1741, harmonized with IEEE 1547. Any inverter which is listed to the UL 1741 standard may be connected to a utility grid without the need for additional anti-islanding equipment, anywhere in the United States or other countries where UL standards are accepted.
Maximum power point tracking (MPPT)
[attachment=39137]
Inverter is simply an electronic device that converts low voltage DC battery power 230 volts AC (Alternating Current) electrical power. They are used in applications ranging from microwaves laptops to satellite systems X-Ray machines etc.
Most industrial applications require high frequency high voltage power supply. These increased power requirements have lead to significant development in inverted technology.
Significant improvements have been made to the traditional pulse width modulations (PWM) Inverters to make power distribution system more efficient and more suitable to reactive power (var) compensation and harmonic filtering.
This includes using multilevel inverters, zero current switching and other power switching devises. Space application involves high power (hundreds of kilowatts to megawatts) systems. Large power conditioning mass reductions are required to enable this megawatt power system.
Therefore inverter design for space applications represents the state - of - the- art in power conditioning technology. Different features such as design parameters, output a characteristics, switching components etc of these inverters used in space application are discussed in the II part of the paper
1.INTRODUCTION
Inverter (electrical)
An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.
Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.
There are two main types of inverter. The output of a modified sine wave inverter is similar to a square wave output except that the output goes to zero volts for a time before switching positive or negative. It is simple and low cost (~$0.10USD/Watt) and is compatible with most electronic devices, except for sensitive or specialized equipment, for example certain laser printers. A pure sine wave inverter produces a nearly perfect sine wave output (<3% total harmonic distortion) that is essentially the same as utility-supplied grid power. Thus it is compatible with all AC electronic devices. This is the type used in grid-tie inverters. Its design is more complex, and costs 5 or 10 times more per unit power (~$0.50 to $1.00USD/Watt). [1] The electrical inverter is a high-power electronic oscillator. It is so named because early mechanical AC to DC converters were made to work in reverse, and thus were "inverted", to convert DC to AC.
The inverter performs the opposite function of a rectifier.
1.1History
Early inverters
From the late nineteenth century through the middle of the twentieth century, DC-to-AC power conversion was accomplished using rotary converters or motor-generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits. The most widely used type of tube was the thyratron.
The origins of electromechanical inverters explain the source of the term inverter. Early AC-to-DC converters used an induction or synchronous AC motor direct-connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame. The result with either is AC-in, DC-out. With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectified AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC. Hence an inverter is an inverted converter.[6][7]
Controlled rectifier inverters
Since early transistors were not available with sufficient voltage and current ratings for most inverter applications, it was the 1957 introduction of the thyristor or silicon-controlled rectifier (SCR) that initiated the transition to solid state inverter circuits.
1.2 Advanced designs
H-bridge inverter circuit with transistor switches and antiparallel diodes
There are many different power circuit topologies and control strategies used in inverter designs. Different design approaches address various issues that may be more or less important depending on the way that the inverter is intended to be used.
1.3How Does a Power Inverter Work? Power Inverters for Cars
To those of us who think AC/DC is just a band, it is helpful to know what that means in terms of power. If you licked your fingers and touched them to a car battery's terminal, you will be experiencing DC, or direct current, power. This is the direct power that is housed in batteries and generators. When you plug your laptop cord into the wall outlet in your home, you are tapping into AC, or alternating current, power. Before direct current power can be used in our electrical devices, an alternator needs to convert the power. In the US, our electrical appliances require 110 AC power (if you have gone abroad, you know that sometimes you need to have a power converter because other countries often use other electrical voltage). A power inverter turns DC power into AC power. So if you have a battery or generator, you can run any electrical appliance. If a storm knocks your power out, you can power a space heater, hot plate, radio, or other necessities. When camping, you can bring all the comforts of home. On long trips in the car, you can plug in your laptop or cell phone to charge. It really is a very versatile and useful device to have.
AC/DC Power Inverter, Car Power Inverter, AC Power Inverter - So Many Choices, So Little Time
So you're at Home Depot wandering around the power inverter aisle. What now? Check the number of outlets the AC power inverter provides. Many have one to three outlets. Do you need a car power inverter or one that is more permanent? Again, think about what you will likely be powering. Before you head out to buy an AC/DC power inverter, it is important to know specifically what type of inverter you need. For instance, you can buy a $30 power inverter from Home Depot, a $450 solar power inverter, or a $2,000 industrial-grade model. You can buy one for your solar panels to increase energy efficiency or one for your RV for use on vacation. The first question is, "What do I need this for?" A close second is, "How much can I spend?" Keep these two factors in mind as you are shopping.
Related to the first question is the type of product you are going to be using the inverter for most often. For instance, if you will need to run oxygen concentrators, fax machines, electric shavers, garage door openers, and high voltage cordless tool chargers, you will need a true-sine inverter. These produce power that is equal - or better - to that from the power grid. For virtually every other electrical appliance, a modified-sine inverter is sufficient. The power is not identical to that which comes from the grid. Instead of a smooth sine wave, it produces one that is choppy. These AC power inverters are perfectly capable of running everything from televisions to computers.
Also consider where you are going to use the inverter. If you want one that will plug into your vehicle cigarette lighter, you should use an inverter that is rated under 300 watts. If the 12-volt lighter has to draw more power than that, it will strain and eventually blow. But 12 volts is enough to power household appliances, computers, and TVs smaller than 27 inches. 600 watt inverters can also be used with 12-volt sources. They can power larger TV, household appliances, bread machines, and 5 amp tools. The next step up for large appliances, larger power tools, microwaves, toasters, and hairdryers requires a 1750 watt appliance. 3000 watts of power can handle nearly all household appliances and office equipment. The wattage you need will depend on the amps needed to run your device; generally power inverters are divided into under 300, 300, 600, 1800, and 3000 and above watts generated. To convert the amps your device takes to watts, simply take the amp number and multiply it by 120; that is your watt
2.Solar inverter
A Solar inverter or PV inverter is a type of electrical inverter that is made to change the direct current (DC) electricity from a photovoltaic array into alternating current (AC) for use with home appliances and possibly a utility grid.
A PV inverter installed in an attic
Solar inverters may be classified into three broad types:
• Stand-alone inverters, used in isolated systems where the inverter draws its DC energy from batteries charged by photovoltaic arrays and/or other sources, such as wind turbines, hydro turbines, or engine generators. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from an AC source, when available. Normally these do not interface in any way with the utility grid, and as such, are not required to have anti-islanding protection.
• Grid tie inverters, which match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages.
• Battery backup inverters. These are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid. These inverters are capable of supplying AC energy to selected loads during a utility outage, and are required to have anti-islanding protection
• Solar inverters use special procedures to deal with the PV array, including maximum power point tracking and anti-islanding protection.
Anti-islanding protection
Normally, grid-tied inverters will shut off if they do not detect the presence of the utility grid. If, however, there are load circuits in the electrical system that happen to resonate at the frequency of the utility grid, the inverter may be fooled into thinking that the grid is still active even after it had been shut down. This is called islanding.
An inverter designed for grid-tie operation will have anti-islanding protection built in; it will inject small pulses that are slightly out of phase with the AC electrical system in order to cancel any stray resonances that may be present when the grid shuts down.
Since 1999, the standard for anti-islanding protection in the United States has been UL 1741, harmonized with IEEE 1547. Any inverter which is listed to the UL 1741 standard may be connected to a utility grid without the need for additional anti-islanding equipment, anywhere in the United States or other countries where UL standards are accepted.
Maximum power point tracking (MPPT)