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77-509: AFE or Afe may refer to: Active front end, in variable-frequency drives Advanced FLOW engineering (aFe), a manufacturer of high performance automotive parts Afe Annang , a political unit of the Annang people of Nigeria AfE-Turm /Uni-Turm (English: AfE Tower), a demolished skyscraper in Frankfurt, Germany Afrique Football Élite ,

154-437: A line-frequency transformer to create the output voltage. A 50% duty cycle square wave is one of the simplest waveforms an inverter design can produce, but adds ~48.3% THD to its fundamental sine wave. Thus, a square wave output can produce undesired "humming" noises when connected to audio equipment and is better suited to low-sensitivity applications such as lighting and heating. A power inverter device that produces

231-537: A phase converter having single-phase converter input and three-phase inverter output. Controller advances have exploited dramatic increases in the voltage and current ratings and switching frequency of solid-state power devices over the past six decades. Introduced in 1983, the insulated-gate bipolar transistor (IGBT) has in the past two decades come to dominate VFDs as an inverter switching device. In variable- torque applications suited for Volts-per-Hertz (V/Hz) drive control, AC motor characteristics require that

308-467: A variable-frequency drive that controls the speed of the motor and thus the compressor and cooling output. The variable-frequency AC from the inverter drives a brushless or induction motor , the speed of which is proportional to the frequency of the AC it is fed, so the compressor can be run at variable speeds—eliminating compressor stop-start cycles increases efficiency. A microcontroller typically monitors

385-557: A VFD system is usually a three-phase induction motor . Some types of single-phase motors or synchronous motors can be advantageous in some situations, but generally three-phase induction motors are preferred as the most economical. Motors that are designed for fixed-speed operation are often used. Elevated-voltage stresses imposed on induction motors that are supplied by VFDs require that such motors be designed for definite-purpose inverter-fed duty in accordance with such requirements as Part 31 of NEMA Standard MG-1. The VFD controller

462-440: A VFD, the stopping sequence is just the opposite as the starting sequence. The frequency and voltage applied to the motor are ramped down at a controlled rate. When the frequency approaches zero, the motor is shut off. A small amount of braking torque is available to help decelerate the load a little faster than it would stop if the motor were simply switched off and allowed to coast. Additional braking torque can be obtained by adding

539-573: A braking circuit (resistor controlled by a transistor) to dissipate the braking energy. With a four-quadrant rectifier (active front-end), the VFD is able to brake the load by applying a reverse torque and injecting the energy back to the AC line. Many fixed-speed motor load applications that are supplied direct from AC line power can save energy when they are operated at variable speed by means of VFD. Such energy cost savings are especially pronounced in variable-torque centrifugal fan and pump applications, where

616-664: A chance to respond to very sudden changes in demand or production. Large inverters, rated at several hundred megawatts, are used to deliver power from high-voltage direct current transmission systems to alternating current distribution systems. A solar inverter is a balance of system (BOS) component of a photovoltaic system and can be used for both grid-connected and off-grid (standalone) systems. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti- islanding protection. Solar micro-inverters differ from conventional inverters, as an individual micro-inverter

693-409: A conveyor application for smoother deceleration and acceleration control, which reduces the backlash that can occur when a conveyor is accelerating or decelerating. Performance factors tending to favor the use of DC drives over AC drives include such requirements as continuous operation at low speed, four-quadrant operation with regeneration, frequent acceleration and deceleration routines, and need for

770-794: A football club in Bamako, Mali Amniotic fluid embolism , a potentially fatal complication of pregnancy Analog front-end , in electronics Armed Forces Entertainment , a United States Department of Defense agency Assembly of French Citizens Abroad , a French government body Association of Spanish Footballers (Spanish: Asociación de Futbolistas Españoles) Authorization for expenditure , also known as cost in accounting Kake Airport , Alaska, United States, by FAA location identifier Putukwam language , by ISO 639-3 language code State Railways Administration of Uruguay (Spanish: Administración de Ferrocarriles del Estado ), Uruguay's government-owned railroad company Topics referred to by

847-424: 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

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924-497: A means for an operator to start and stop the motor and adjust the operating speed. The VFD may also be controlled by a programmable logic controller through Modbus or another similar interface. Additional operator control functions might include reversing, and switching between manual speed adjustment and automatic control from an external process control signal. The operator interface often includes an alphanumeric display or indication lights and meters to provide information about

1001-422: 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 . 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

1078-406: A pure electrical means of communication. Typical means of hardwired communication are: 4-20mA , 0-10VDC, or using the internal 24VDC power supply with a potentiometer . Speed can also be controlled remotely and locally. Remote control instructs the VFD to ignore speed commands from the keypad while local control instructs the VFD to ignore external control and only abide by the keypad. Depending on

1155-452: A pure sine wave. If the waveform is chosen to have its peak voltage 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,

1232-408: A semiconductor device, and can readily be controlled over a variable firing range. The switch in the simple inverter described above, when not coupled to an output transformer, produces a square voltage waveform due to its simple off and on nature as opposed to the sinusoidal waveform that is the usual waveform of an AC power supply. Using Fourier analysis , periodic waveforms are represented as

1309-669: 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. Switched-mode power supply (SMPS) devices, such as personal computers or DVD players, function on modified sine wave power. 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. The modified sine wave

1386-456: 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. Some inverters use PWM to create a waveform that can be low pass filtered to re-create the sine wave. These only require one DC supply, in the manner of the MSN designs, but

1463-534: A step-up transformer is placed between a LV drive and a MV motor load. MV drives are typically rated for motor applications greater than between about 375 and 750 kW (503 and 1,006 hp). MV drives have historically required considerably more application design effort than required for LV drive applications. The power rating of MV drives can reach 100 MW (130,000 hp), a range of different drive topologies being involved for different rating, performance, power quality, and reliability requirements. It

1540-436: A wide range of single-phase and multi-phase AC motors. Low-voltage (LV) drives are designed to operate at output voltages equal to or less than 690 V. While motor-application LV drives are available in ratings of up to the order of 5 or 6 MW, economic considerations typically favor medium-voltage (MV) drives with much lower power ratings. Different MV drive topologies (see Table 2) are configured in accordance with

1617-546: Is a solid-state power electronics conversion system consisting of three distinct sub-systems: a rectifier bridge converter, a direct current (DC) link, and an inverter. Voltage-source inverter (VSI) drives (see 'Generic topologies' sub-section below) are by far the most common type of drives. Most drives are AC–AC drives in that they convert AC line input to AC inverter output. However, in some applications such as common DC bus or solar applications, drives are configured as DC–AC drives. The most basic rectifier converter for

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1694-400: Is also often available to allow the VFD to be configured, adjusted, monitored, and controlled using a computer. There are two main ways to control the speed of a VFD; networked or hardwired. Networked involves transmitting the intended speed over a communication protocol such as Modbus , Modbus / TCP , EtherNet/IP , or via a keypad using Display Serial Interface while hardwired involves

1771-576: Is attached to each solar panel. This can improve the overall efficiency of the system. The output from several micro-inverters is then combined and often fed to the electrical grid . In other applications, a conventional inverter can be combined with a battery bank maintained by a solar charge controller. This combination of components is often referred to as a solar generator. Solar inverters are also used in spacecraft photovoltaic systems . Inverters convert low frequency main AC power to higher frequency for use in induction heating . To do this, AC power

1848-596: Is constructed from intersections of a saw-toothed carrier signal with a modulating sinusoidal signal which is variable in operating frequency as well as in voltage (or current). Operation of the motors above rated nameplate speed (base speed) is possible, but is limited to conditions that do not require more power than the nameplate rating of the motor. This is sometimes called "field weakening" and, for AC motors, means operating at less than rated V/Hz and above rated nameplate speed. Permanent magnet synchronous motors have quite limited field-weakening speed range due to

1925-558: 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. Formula to calculate inverter battery capacity: Battery Capacity (Ah) = Total Load (In Watts) × Usage Time (in hours) / Input Voltage (V) When attempting to add more batteries to an inverter, there are two basic options for installation: An inverter converts

2002-421: Is different from Wikidata All article disambiguation pages All disambiguation pages Variable-frequency drive A variable-frequency drive ( VFD , or adjustable-frequency drive , adjustable-speed drive , variable-speed drive , AC drive , micro drive , inverter drive , or drive ) is a type of AC motor drive (system incorporating a motor) that controls speed and torque by varying

2079-414: Is drawing less than 50% of its rated current from the mains in the low-speed range. A VFD can be adjusted to produce a steady 150% starting torque from standstill right up to full speed. However, motor cooling deteriorates and can result in overheating as speed decreases such that prolonged low-speed operation with significant torque is not usually possible without separately motorized fan ventilation. With

2156-443: Is estimated that drive technology is adopted in as many as 30–40% of all newly installed motors. An energy consumption breakdown of the global population of AC motor installations is as shown in the following table: AC drives are used to bring about process and quality improvements in industrial and commercial applications' acceleration, flow, monitoring, pressure, speed, temperature, tension, and torque. Fixed-speed loads subject

2233-663: Is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power. Due to the reduction in the number of DC sources employed, the structure becomes more reliable and the output voltage has higher resolution due to an increase in the number of steps so that the reference sinusoidal voltage can be better achieved. This configuration has recently become very popular in AC power supply and adjustable speed drive applications. This new inverter can avoid extra clamping diodes or voltage balancing capacitors. There are three kinds of level shifted modulation techniques, namely: With HVDC power transmission, AC power

2310-400: Is in designs for motor driving, where a variable frequency results in a variable speed control. Also, 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. The AC output voltage of a power inverter is often regulated to be the same as the grid line voltage, typically 120 or 240 VAC at

2387-405: Is lastly useful to relate VFDs in terms of the following two classifications: CSI or VSI (six-step or PWM ), cycloconverter, matrix Electro-mechanical Slip energy recovery (Kramer/Scherbius) CSI (LCI), cycloconverter, VSI Axial or disk Interior VSI VSI VSI Topologies Power inverter The input voltage , output voltage and frequency, and overall power handling depend on

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2464-519: 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. Most AC motors will run on MSW inverters with an efficiency reduction of about 20% owing to

2541-417: Is rectified and high voltage DC power is transmitted to another location. At the receiving location, an inverter in a HVDC converter station converts the power back into AC. The inverter must be synchronized with grid frequency and phase and minimize harmonic generation. Electroshock weapons and tasers have a DC/AC inverter to generate several tens of thousands of V AC out of a small 9 V DC battery. First

2618-416: Is restored, a rectifier supplies DC power to recharge the batteries. 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. Control and feedback circuitry is used to adjust the final output of the inverter section which will ultimately determine

2695-422: Is the sum of two square waves , one of which is delayed one-quarter of the period with respect to the other. The result is a repeated voltage step sequence of zero, peak positive, zero, peak negative, and again zero. The resultant voltage waveform better approximates the shape of a sinusoidal voltage waveform than a single square wave. Most inexpensive consumer power inverters produce a modified sine wave rather than

2772-745: The frequency of the input electricity. Depending on its topology , it controls the associated voltage or current variation. VFDs are used in applications ranging from small appliances to large compressors. Systems using VFDs can be more efficient than hydraulic systems , such as in systems with pumps and damper control for fans. Since the 1980s, power electronics technology has reduced VFD cost and size and has improved performance through advances in semiconductor switching devices, drive topologies, simulation and control techniques, and control hardware and software. VFDs include low- and medium-voltage AC–AC and DC–AC topologies. Pulse-Width Modulating (PWM) variable-frequency drive projects started in

2849-545: The 1960s at Strömberg in Finland. Martti Harmoinen  [ fi ] is regarded as the inventor of this technology. Strömberg managed to sell the idea of PWM drive to Helsinki Metro in 1973 and in 1982 the first PWM drive SAMI10 were operational. A variable-frequency drive is a device used in a drive system consisting of the following three main sub-systems: AC motor, main drive controller assembly, and drive/operator interface. The AC electric motor used in

2926-410: The 9 V DC is converted to 400–2000 V AC with a compact high frequency transformer, which is then rectified and temporarily stored in a high voltage capacitor until a pre-set threshold voltage is reached. When the threshold (set by way of an airgap or TRIAC) is reached, the capacitor dumps its entire load into a pulse transformer which then steps it up to its final output voltage of 20–60 kV. A variant of

3003-401: 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. An uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when mains power is not available. When mains power

3080-432: The DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit. The electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of

3157-463: The United States, an estimated 60–65% of electrical energy is used to supply motors, 75% of which are variable-torque fan, pump, and compressor loads. Eighteen percent of the energy used in the 40 million motors in the U.S. could be saved by efficient energy improvement technologies such as VFDs. Only about 3% of the total installed base of AC motors are provided with AC drives. However, it

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3234-426: The VFD controller. Basic programming of the microprocessor is provided as user-inaccessible firmware . User programming of display , variable, and function block parameters is provided to control, protect, and monitor the VFD, motor, and driven equipment. The basic drive controller can be configured to selectively include such optional power components and accessories as follows: The operator interface provides

3311-674: The VSI drive is configured as a three-phase, six-pulse, full-wave diode bridge . In a VSI drive, the DC link consists of a capacitor which smooths out the converter's DC output ripple and provides a stiff input to the inverter. This filtered DC voltage is converted to quasi- sinusoidal AC voltage output using the inverter's active switching elements. VSI drives provide higher power factor and lower harmonic distortion than phase-controlled current-source inverter (CSI) and load-commutated inverter (LCI) drives (see 'Generic topologies' sub-section below). The drive controller can also be configured as

3388-544: The chart's four quadrants are defined as follows: Most applications involve single-quadrant loads operating in quadrant I, such as in variable-torque (e.g. centrifugal pumps or fans) and certain constant-torque (e.g. extruders) loads. Certain applications involve two-quadrant loads operating in quadrant I and II where the speed is positive but the torque changes polarity as in case of a fan decelerating faster than natural mechanical losses. Some sources define two-quadrant drives as loads operating in quadrants I and III where

3465-430: The constant magnet flux linkage . Wound-rotor synchronous motors and induction motors have much wider speed range. For example, a 100 HP, 460 V, 60 Hz, 1775  RPM (4-pole) induction motor supplied with 460 V, 75 Hz (6.134 V/Hz), would be limited to 60/75 = 80% torque at 125% speed (2218.75 RPM) = 100% power. At higher speeds, the induction motor torque has to be limited further due to

3542-427: The contactor thus turns on the drive and has it output to a designated speed. Depending on the sophistication of the drive multiple auto-starting behavior can be developed e.g. the drive auto-starts on power up but does not auto-start from clearing an emergency stop until a reset has been cycled. Referring to the accompanying chart, drive applications can be categorized as single-quadrant, two-quadrant, or four-quadrant;

3619-461: The current waveform introduces additional heating and can produce pulsating torques. Numerous items of electric equipment will operate quite well on modified sine wave power inverter devices, especially loads that are resistive in nature such as traditional incandescent light bulbs. Items with a switched-mode power supply operate almost entirely without problems, but if the item has a mains transformer, this can overheat depending on how marginally it

3696-482: The design of the specific device or circuitry. The inverter does not produce any power; the power is provided by the DC source. A power inverter can be entirely electronic or maybe a combination of mechanical effects (such as a rotary apparatus) and electronic circuitry. Static inverters do not use moving parts in the conversion process. Power inverters are primarily used in electrical power applications where high currents and voltages are present; circuits that perform

3773-444: The developed pattern and thus the output is obtained. An inverter can be used to control the speed of the compressor motor to drive variable refrigerant flow in a refrigeration or air conditioning system to regulate system performance. Such installations are known as inverter compressors . Traditional methods of refrigeration regulation use single-speed compressors switched on and off periodically; inverter-equipped systems have

3850-526: The developed pattern to obtain the desired output. The harmonic spectrum in the output depends on the width of the pulses and the modulation frequency. It can be shown that the minimum distortion of a three-level waveform is reached when the pulses extend over 130 degrees of the waveform, but the resulting voltage will still have about 30% THD, higher than commercial standards for grid-connected power sources. When operating induction motors, voltage harmonics are usually not of concern; however, harmonic distortion in

3927-457: 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 150 to 3000 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. The runtime of an inverter powered by batteries

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4004-404: 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. A power inverter will often have an overall power rating expressed in watts or kilowatts. This describes the power that will be available to

4081-522: The harmonic content. However, they may be quite noisy. A series LC filter tuned to the fundamental frequency may help. A common modified sine wave inverter topology found in consumer power inverters is as follows: An onboard microcontroller rapidly switches on and off power MOSFETs at high frequency like ~50 kHz. The MOSFETs directly pull from a low voltage DC source (such as a battery). This signal then goes through step-up transformers (generally many smaller transformers are placed in parallel to reduce

4158-494: The harmonic spectrum can be changed. The lowest THD for a three-step modified sine wave is 30% when the pulses are at 130 degrees width of each electrical cycle. This is slightly lower than for a square wave. The ratio of on to off time can be adjusted to vary the RMS voltage while maintaining a constant frequency with a technique called pulse-width modulation (PWM). The generated gate pulses are given to each switch in accordance with

4235-444: The inverter. Examples include: An inverter may produce a square wave , sine wave , modified sine wave, pulsed sine wave, or near-sine pulse-width modulated wave (PWM) depending on circuit design. Common types of inverters produce square waves or quasi-square waves. One measure of the purity of a sine wave is the total harmonic distortion (THD). Technical standards for commercial power distribution grids require less than 3% THD in

4312-480: The line and have as little harmonic content as possible. They also need a means of detecting the presence of utility power for safety reasons, so as not to continue to dangerously feed power to the grid during a power outage. Synchronverters are inverters that are designed to simulate a rotating generator, and can be used to help stabilize grids. They can be designed to react faster than normal generators to changes in grid frequency, and can give conventional generators

4389-420: The load's torque and power vary with the square and cube , respectively, of the speed. This change gives a large power reduction compared to fixed-speed operation for a relatively small reduction in speed. For example, at 63% speed a motor load consumes only 25% of its full-speed power. This reduction is in accordance with affinity laws that define the relationship between various centrifugal load variables. In

4466-418: The lowering of the breakaway torque of the motor. Thus, rated power can be typically produced only up to 130–150% of the rated nameplate speed. Wound-rotor synchronous motors can be run at even higher speeds. In rolling mill drives, often 200–300% of the base speed is used. The mechanical strength of the rotor limits the maximum speed of the motor. An embedded microprocessor governs the overall operation of

4543-433: The model a VFD's operating parameters can be programmed via: dedicated programming software, internal keypad, external keypad, or SD card. VFDs will often block out most programming changes while running. Typical parameters that need to be set include: motor nameplate information, speed reference source, on/off control source and braking control. It is also common for VFDs to provide debugging information such as fault codes and

4620-492: The motor to a high starting torque and to current surges that are up to eight times the full-load current. AC drives instead gradually ramp the motor up to operating speed to lessen mechanical and electrical stress, reducing maintenance and repair costs, and extending the life of the motor and the driven equipment. Variable-speed drives can also run a motor in specialized patterns to further minimize mechanical and electrical stress. For example, an S-curve pattern can be applied to

4697-481: The motor to be protected for a hazardous area. The following table compares AC and DC drives according to certain key parameters: ^ High-frequency injection AC drives can be classified according to the following generic topologies: Most drives use one or more of the following control platforms: Variable-frequency drives are also categorized by the following load torque and power characteristics: VFDs are available with voltage and current ratings covering

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4774-433: The motor voltage magnitude, angle from reference, and frequency so as to precisely control the motor's magnetic flux and mechanical torque. Although space vector pulse-width modulation (SVPWM) is becoming increasingly popular, sinusoidal PWM (SPWM) is the most straightforward method used to vary drives' motor voltage (or current) and frequency. With SPWM control (see Fig. 1), quasi-sinusoidal, variable-pulse-width output

4851-453: The operation of the drive. An operator interface keypad and display unit is often provided on the front of the VFD controller as shown in the photograph above. The keypad display can often be cable-connected and mounted a short distance from the VFD controller. Most are also provided with input and output (I/O) terminals for connecting push buttons, switches, and other operator interface devices or control signals. A serial communications port

4928-409: 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. Finally, this DC supply is pulsed with additional power MOSFETs by the microcontroller to produce the final modified sine wave signal. More complex inverters use more than two voltages to form a multiple-stepped approximation to

5005-416: The principle is also used in electronic flash and bug zappers , though they rely on a capacitor-based voltage multiplier to achieve their high voltage. Typical applications for power inverters include: In one simple inverter circuit, DC power is connected to a transformer through the center tap of the primary winding. A relay switch is rapidly switched back and forth to allow current to flow back to

5082-423: The same function for electronic signals, which usually have very low currents and voltages, are called oscillators . Circuits that perform the opposite function, converting AC to DC, are called rectifiers. A typical power inverter device or circuit requires a stable DC power source capable of supplying enough current for the intended power demands of the system. The input voltage depends on the design and purpose of

5159-402: The same polarity. In starting a motor, a VFD initially applies a low frequency and voltage, thus avoiding high inrush-current associated with direct-on-line starting . After the start of the VFD, the applied frequency and voltage are increased at a controlled rate or ramped up to accelerate the load. This starting method typically allows a motor to develop 150% of its rated torque while the VFD

5236-450: The same term [REDACTED] This disambiguation page lists articles associated with the title AFE . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=AFE&oldid=1249927800 " Category : Disambiguation pages Hidden categories: Articles containing Spanish-language text Short description

5313-435: The speed and torque is same (positive or negative) polarity in both directions. Certain high-performance applications involve four-quadrant loads (Quadrants I to IV) where the speed and torque can be in any direction such as in hoists, elevators, and hilly conveyors. Regeneration can occur only in the drive's DC link bus when inverter voltage is smaller in magnitude than the motor back- EMF and inverter voltage and back-EMF are

5390-455: The speed of the motor operating under its mechanical load. Motor speed control needs are numerous and include things like: industrial motor driven equipment, electric vehicles, rail transport systems, and power tools. (See related: variable-frequency drive ) Switching states are developed for positive, negative, and zero voltages as per the patterns given in the switching Table 1. The generated gate pulses are given to each switch in accordance with

5467-404: The states of the input signals. Most VFDs allow auto-starting to be enabled. Which will drive the output to a designated frequency after a power cycle, or after a fault has been cleared, or after the emergency stop signal has been restored (generally emergency stops are active low logic). One popular way to control a VFD is to enable auto-start and place L1, L2, and L3 into a contactor. Powering on

5544-768: The stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch so that the switch continually switches rapidly back and forth. This type of electromechanical inverter switch, called a vibrator or buzzer, was once used in vacuum tube automobile radios. A similar mechanism has been used in door bells, buzzers, and tattoo machines . As they became available with adequate power ratings, transistors , and various other types of semiconductor switches have been incorporated into inverter circuit designs. Certain ratings, especially for large systems (many kilowatts) use thyristors (SCR). SCRs provide large power handling capability in

5621-412: The switching takes place at a far faster rate, typically many kHz, so that the varying width of the pulses can be smoothed to create the sine wave. If a microprocessor is used to generate the switching timing, the harmonic content and efficiency can be closely controlled. The AC output frequency of a power inverter device is usually the same as standard power line frequency, 50 or 60 hertz . The exception

5698-509: The temperature in the space to be cooled, and adjusts the speed of the compressor to maintain the desired temperature. The additional electronics and system hardware add cost to the equipment, but can result in substantial savings in operating costs. The first inverter air conditioners were released by Toshiba in 1981, in Japan. Grid-tied inverters are designed to feed into the electric power distribution system. They transfer synchronously with

5775-691: The voltage magnitude of the inverter's output to the motor be adjusted to match the required load torque in a linear V/Hz relationship. For example, for 460 V, 60 Hz motors, this linear V/Hz relationship is 460/60 = 7.67 V/Hz. While suitable in wide-ranging applications, V/Hz control is sub-optimal in high-performance applications involving low speed or demanding, dynamic speed regulation, positioning, and reversing load requirements. Some V/Hz control drives can also operate in quadratic V/Hz mode or can even be programmed to suit special multi-point V/Hz paths. The two other drive control platforms, vector control and direct torque control (DTC), adjust

5852-421: The voltage/current-combination ratings used in different drive controllers' switching devices such that any given voltage rating is greater than or equal to one to the following standard nominal motor voltage ratings: generally either 2 + 3 ⁄ 4 .16 kV (60 Hz) or 3 + 3 ⁄ 6 .6 kV (50 Hz), with one thyristor manufacturer rated for up to 12 kV switching. In some applications

5929-413: The wave shape at the customer's point of connection. IEEE Standard 519 recommends less than 5% THD for systems connecting to a power grid. 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

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