Voltage Regulator Handbook National Semiconductor Corporation
Voltage regulator - Wikipedia, the free encyclopedia. An integrated circuit voltage regulator in a TO- 2.
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Voltage Regulator Handbook Pdf 2015.01.03 - Teledyne Philbrick 1461 FET Power Op-amp datasheet pdf 2015.01.03 - Intersil Voltage Regulator Handbook, 1978. A voltage regulator is designed to. Initial accuracy of a voltage regulator (or simply 'the voltage. Linear & Switching Voltage Regulator Handbook.
Voltage Regulator. A voltage stabilizer is an electronic device able to deliver relatively constant output voltage while input voltage and load current changes over. Non è possibile visualizzare una descrizione perché il sito non lo consente. Voltage Regulator Handbook The voltage regulators provide clean, stable power in a step-down configuration. OSDoge can be powered from the USB port, and does not. Non è necessario possedere un dispositivo Kindle. Scarica una delle app Kindle gratuite per iniziare a leggere i libri Kindle sul tuo smartphone, tablet e computer.
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Such devices are popular because they require few or no external components and provide the functions of pass element, voltage reference, and protection from overcurrent in one package. A voltage regulator is designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed- forward" design or may include negative feedbackcontrol loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages. Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements.
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In automobile alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.
Electronic voltage regulators[edit]A simple voltage regulator can be made from a resistor in series with a diode (or series of diodes). Due to the logarithmic shape of diode V- I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. When precise voltage control and efficiency are not important, this design may work fine. Feedback voltage regulators operate by comparing the actual output voltage to some fixed reference voltage. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error. This forms a negative feedbackcontrol loop; increasing the open- loop gain tends to increase regulation accuracy but reduce stability. Stability is avoidance of oscillation, or ringing, during step changes.) There will also be a trade- off between stability and the speed of the response to changes.
If the output voltage is too low (perhaps due to input voltage reducing or load current increasing), the regulation element is commanded, up to a point, to produce a higher output voltage–by dropping less of the input voltage (for linear series regulators and buckswitching regulators), or to draw input current for longer periods (boost- type switching regulators); if the output voltage is too high, the regulation element will normally be commanded to produce a lower voltage. However, many regulators have over- current protection, so that they will entirely stop sourcing current (or limit the current in some way) if the output current is too high, and some regulators may also shut down if the input voltage is outside a given range (see also: crowbar circuits). Electromechanical regulators[edit].
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Circuit design for a simple electromechanical voltage regulator. A voltage stabilizer using electromechanical relays for switching. Graph of voltage output on a time scale.
In electromechanical regulators, voltage regulation is easily accomplished by coiling the sensing wire to make an electromagnet. The magnetic field produced by the current attracts a moving ferrous core held back under spring tension or gravitational pull. As voltage increases, so does the current, strengthening the magnetic field produced by the coil and pulling the core towards the field. The magnet is physically connected to a mechanical power switch, which opens as the magnet moves into the field. As voltage decreases, so does the current, releasing spring tension or the weight of the core and causing it to retract.
This closes the switch and allows the power to flow once more. If the mechanical regulator design is sensitive to small voltage fluctuations, the motion of the solenoid core can be used to move a selector switch across a range of resistances or transformer windings to gradually step the output voltage up or down, or to rotate the position of a moving- coil AC regulator. Early automobilegenerators and alternators had a mechanical voltage regulator using one, two, or three relays and various resistors to stabilize the generator's output at slightly more than 6 or 1. V, independent of the engine's rpm or the varying load on the vehicle's electrical system.
Essentially, the relay(s) employed pulse width modulation to regulate the output of the generator, controlling the field current reaching the generator (or alternator) and in this way controlling the output voltage producing back into the generator and attempting to run it as a motor. The rectifierdiodes in an alternator automatically perform this function so that a specific relay is not required; this appreciably simplified the regulator design. More modern designs now use solid state technology (transistors) to perform the same function that the relays perform in electromechanical regulators.
Electromechanical regulators are used for mains voltage stabilisation — see AC voltage stabilizers below. Automatic voltage regulator[edit]. Voltage regulator for generators. To control the output of generators (as seen in ships and power stations, or on oil rigs, greenhouses and emergency power systems) automatic voltage regulators are used. This is an active system. While the basic principle is the same, the system itself is more complex.
An automatic voltage regulator (or AVR for short) consists of several components such as diodes, capacitors, resistors and potentiometers or even microcontrollers, all placed on a circuit board. This is then mounted near the generator and connected with several wires to measure and adjust the generator.
How an AVR works: In the first place the AVR monitors the output voltage and controls the input voltage for the exciter of the generator. By increasing or decreasing the generator control voltage, the output voltage of the generator increases or decreases accordingly. The AVR calculates how much voltage has to be sent to the exciter numerous times a second, therefore stabilizing the output voltage to a predetermined setpoint. When two or more generators are powering the same system (parallel operation) the AVR receives information from more generators to match all output. AC voltage stabilizers[edit]Coil- rotation AC voltage regulator[edit]. Basic design principle and circuit diagram for the rotating- coil AC voltage regulator. This is an older type of regulator used in the 1.
When the movable coil is positioned perpendicular to the fixed coil, the magnetic forces acting on the movable coil balance each other out and voltage output is unchanged. Rotating the coil in one direction or the other away from the center position will increase or decrease voltage in the secondary movable coil. This type of regulator can be automated via a servo control mechanism to advance the movable coil position in order to provide voltage increase or decrease.
A braking mechanism or high ratio gearing is used to hold the rotating coil in place against the powerful magnetic forces acting on the moving coil. Electromechanical[edit]Electromechanical regulators called voltage stabilizers or tap- changers, have also been used to regulate the voltage on AC power distribution lines. These regulators operate by using a servomechanism to select the appropriate tap on an autotransformer with multiple taps, or by moving the wiper on a continuously variable auto transfomer. If the output voltage is not in the acceptable range, the servomechanism switches the tap, changing the turns ratio of the transformer, to move the secondary voltage into the acceptable region. The controls provide a dead band wherein the controller will not act, preventing the controller from constantly adjusting the voltage ("hunting") as it varies by an acceptably small amount.
PWM static voltage regulator[edit]This is the latest technology of voltage regulation to provide real- time control of voltage fluctuation, sag, surge and also to control other power quality issues such as spikes and EMI/RFI electrical noises. This uses an IGBT regulator engine generating pulse width modulated (PWM) AC voltage at high switching frequency. This AC PWM wave is superimposed on the main incoming wave through a buck- boost transformer, to provide precisely regulated AC voltage. The regulation in this technology is instantaneous, thus making it suitable for electronic machines which need precise regulated power.
Constant- voltage transformer[edit]The ferroresonant transformer, ferroresonant regulator or constant- voltage transformer is a type of saturating transformer used as a voltage regulator. These transformers use a tank circuit composed of a high- voltage resonant winding and a capacitor to produce a nearly constant average output voltage with a varying input current or varying load. The circuit has a primary on one side of a magnet shunt and the tuned circuit coil and secondary on the other side. The regulation is due to magnetic saturation in the section around the secondary. The ferroresonant approach is attractive due to its lack of active components, relying on the square loop saturation characteristics of the tank circuit to absorb variations in average input voltage. Saturating transformers provide a simple rugged method to stabilize an AC power supply. Older designs of ferroresonant transformers had an output with high harmonic content, leading to a distorted output waveform.
Modern devices are used to construct a perfect sine wave. The ferroresonant action is a flux limiter rather than a voltage regulator, but with a fixed supply frequency it can maintain an almost constant average output voltage even as the input voltage varies widely. The ferroresonant transformers, which are also known as Constant Voltage Transformers (CVTs) or ferros, are also good surge suppressors, as they provide high isolation and inherent short- circuit protection. A ferroresonant transformer can operate with an input voltage range В±4. Output power factor remains in the range of 0.