Rectifier - Wikipedia, the free encyclopedia. A rectifier is an electrical device that convertsalternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification. Physically, rectifiers take a number of forms, including vacuum tubediodes, mercury- arc valves, copper and selenium oxide rectifiers, semiconductor diodes, silicon- controlled rectifiers and other silicon- based semiconductor switches. Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios, used a . Rectification may serve in roles other than to generate direct current for use as a source of power. DF005S - DF10S — Bridge Rectifiers . 1.5 3 Electrical Characteristics Values are at TA = 25. Before the development of silicon semiconductor rectifiers, vacuum tube thermionic diodes and copper oxide- or selenium-based metal rectifier stacks were used. With the introduction of semiconductor. The diode bridge circuit was invented by Polish electrotechnician Karol Pollak and patented on 14 Jan, 1896 under the number. Wikimedia Commons has media related to Bridge rectifiers. Www.taitroncomponents.com ISO 9001 Certified Tel : Fax: (800)TAITRON (800)TAITFAX (800)824-8766 20141011 (800)824-8329 -1-Bridge Rectifiers Bridge Part No. Average Rectified Current Peak Repetitive Reverse. As noted, detectors of radio signals serve as rectifiers. In gas heating systems flame rectification is used to detect presence of a flame. Because of the alternating nature of the input AC sine wave, the process of rectification alone produces a DC current that, though unidirectional, consists of pulses of current. Many applications of rectifiers, such as power supplies for radio, television and computer equipment, require a steady constant DC current (as would be produced by a battery). In these applications the output of the rectifier is smoothed by an electronic filter (usually a capacitor) to produce a steady current. More complex circuitry that performs the opposite function, converting DC to AC, is called an inverter. Rectifier devices. Vishay Intertechnology’s New 1 A Miniature Glass Passivated Single-Phase Bridge Rectifiers Feature Reverse Voltages to 1000 V in Low-Profile MBLS Package for Smartphone Chargers May 09, 2013. MB2M, MB4M, MB6M www.vishay.com Vishay General Semiconductor Revision: 16-Aug-13 3 Document Number: 88660 For technical questions within your region: [email protected], [email protected], [email protected]. Rectifiers datasheet, pdf, silicon bridge rectifiers glass passivated bridge rectifiers, silicon bridge rectifiers glass passivated bridge rectifiers, silicon bridge rectifiers glass passivated bridge rectifiers. For power rectification from very low to very high current, semiconductor diodes of various types (junction diodes, Schottky diodes, etc.) are widely used. Other devices that have control electrodes as well as acting as unidirectional current valves are used where more than simple rectification is required. High- power rectifiers, such as those used in high- voltage direct current power transmission, employ silicon semiconductor devices of various types. These are thyristors or other controlled switching solid- state switches, which effectively function as diodes to pass current in only one direction. Rectifier circuits. Most low power rectifiers for domestic equipment are single- phase, but three- phase rectification is very important for industrial applications and for the transmission of energy as DC (HVDC). Single- phase rectifiers. Because only one half of the input waveform reaches the output, mean voltage is lower. Half- wave rectification requires a single diode in a single- phase supply, or three in a three- phase supply. Rectifiers yield a unidirectional but pulsating direct current; half- wave rectifiers produce far more ripple than full- wave rectifiers, and much more filtering is needed to eliminate harmonics of the AC frequency from the output. The no- load output DC voltage of an ideal half- wave rectifier for a sinusoidal input voltage is. Full- wave rectification converts both polarities of the input waveform to pulsating DC (direct current), and yields a higher average output voltage. Two diodes and a center tappedtransformer, or four diodes in a bridge configuration and any AC source (including a transformer without center tap), are needed. Twice as many turns are required on the transformer secondary to obtain the same output voltage than for a bridge rectifier, but the power rating is unchanged. The 5. U4 and 5. Y3 were popular examples of this configuration. Three- phase rectifiers. However, for most industrial and high- power applications, three- phase rectifier circuits are the norm. As with single- phase rectifiers, three- phase rectifiers can take the form of a half- wave circuit, a full- wave circuit using a center- tapped transformer, or a full- wave bridge circuit. Thyristors are commonly used in place of diodes to create a circuit that can regulate the output voltage. Many devices that provide direct current actually generate three- phase AC. For example, an automobile alternator contains six diodes, which function as a full- wave rectifier for battery charging. Three- phase, half- wave circuit. This is the simplest type of three- phase rectifier but suffers from relatively high harmonic distortion on both the AC and DC connections. This type of rectifier is said to have a pulse- number of three, since the output voltage on the DC side contains three distinct pulses per cycle of the grid frequency. Three- phase, full- wave circuit using center- tapped transformer. This rectifier now requires six diodes, one connected to each end of each transformer secondary winding. This circuit has a pulse- number of six, and in effect, can be thought of as a six- phase, half- wave circuit. Before solid state devices became available, the half- wave circuit, and the full- wave circuit using a center- tapped transformer, were very commonly used in industrial rectifiers using mercury- arc valves. For this reason, it is also commonly referred to as a six- pulse bridge. For low- power applications, double diodes in series, with the anode of the first diode connected to the cathode of the second, are manufactured as a single component for this purpose. Some commercially available double diodes have all four terminals available so the user can configure them for single- phase split supply use, half a bridge, or three- phase rectifier. For higher- power applications, a single discrete device is usually used for each of the six arms of the bridge. For the very highest powers, each arm of the bridge may consist of tens or hundreds of separate devices in parallel (where very high current is needed, for example in aluminium smelting) or in series (where very high voltages are needed, for example in high- voltage direct current power transmission). In practice, the supply inductance causes a reduction of DC output voltage with increasing load, typically in the range 1. As result of this is that at each transition between a pair of devices, there is a period of overlap during which three (rather than two) devices in the bridge are conducting simultaneously. The overlap angle is usually referred to by the symbol . For very high- power rectifiers the twelve- pulse bridge connection is usually used. A twelve- pulse bridge consists of two six- pulse bridge circuits connected in series, with their AC connections fed from a supply transformer that produces a 3. This cancels many of the characteristic harmonics the six- pulse bridges produce. The 3. 0 degree phase shift is usually achieved by using a transformer with two sets of secondary windings, one in star (wye) connection and one in delta connection. Voltage- multiplying rectifiers. By combining both of these with separate output smoothing it is possible to get an output voltage of nearly double the peak AC input voltage. This also provides a tap in the middle, which allows use of such a circuit as a split rail power supply. A variant of this is to use two capacitors in series for the output smoothing on a bridge rectifier then place a switch between the midpoint of those capacitors and one of the AC input terminals. With the switch open, this circuit acts like a normal bridge rectifier. With the switch closed, it act like a voltage doubling rectifier. In other words, this makes it easy to derive a voltage of roughly 3. V (. However, for a given desired ripple, the value of both capacitors must be twice the value of the single one required for a normal bridge rectifier; when the switch is closed each one must filter the output of a half- wave rectifier, and when the switch is open the two capacitors are connected in series with an equivalent value of half one of them. These circuits are capable of producing a DC output voltage potential tens of times that of the peak AC input voltage, but are limited in current capacity and regulation. Diode voltage multipliers, frequently used as a trailing boost stage or primary high voltage (HV) source, are used in HV laser power supplies, powering devices such as cathode ray tubes (CRT) (like those used in CRT based television, radar and sonar displays), photon amplifying devices found in image intensifying and photo multiplier tubes (PMT), and magnetron based radio frequency (RF) devices used in radar transmitters and microwave ovens. Before the introduction of semiconductor electronics, transformerless powered vacuum tube receivers powered directly from AC power sometimes used voltage doublers to generate about 1. VDC from a 1. 00. Even with ideal rectifiers with no losses, the efficiency is less than 1. AC power rather than DC which manifests as ripple superimposed on the DC waveform. For a half- wave rectifier efficiency is very poor. Efficiency can be improved with the use of smoothing circuits which reduce the ripple and hence reduce the AC content of the output. Three- phase rectifiers, especially three- phase full- wave rectifiers, have much greater efficiencies because the ripple is intrinsically smaller. In some three- phase and multi- phase applications the efficiency is high enough that smoothing circuitry is unnecessary. Unlike an ideal rectifier, it dissipates some power. An aspect of most rectification is a loss from the peak input voltage to the peak output voltage, caused by the built- in voltage drop across the diodes (around 0. V for ordinary silicon p. Half- wave rectification and full- wave rectification using a center- tapped secondary produces a peak voltage loss of one diode drop. Bridge rectification has a loss of two diode drops. This reduces output voltage, and limits the available output voltage if a very low alternating voltage must be rectified. As the diodes do not conduct below this voltage, the circuit only passes current through for a portion of each half- cycle, causing short segments of zero voltage (where instantaneous input voltage is below one or two diode drops) to appear between each . Note the ripple in the DC signal. While half- wave and full- wave rectification can deliver unidirectional current, neither produces a constant voltage. Datasheet - Datasheet Archive.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
January 2017
Categories |