What a stabilizer looks like. Useful information about stabilizers. Disadvantages of a static voltage regulator

Many people have experienced sudden power surges, as a result of which all household appliances in the house fail. Is it possible to somehow prevent them and protect expensive devices from breakdown? In this article, we will analyze, what they are and how they work.

Modern electrical networks, unfortunately, do not provide a constant voltage to the outlet. Depending on the place of residence, the number of subscribers and the power of devices on one line, the voltage can vary greatly from 180 to 240 volts.

A modern stabilizer looks like this

But most of today's electronics are extremely negative about such experiments, since the limit for it jumps to + -10 volts. For example, a TV or computer may simply turn off if the voltage drops to 210, which happens quite often, especially in the evening.

It is not necessary to count on the fact that the power grids will be modernized in the coming years. Therefore, citizens need to independently take care of the "equalization" of the voltage and protection of power grids. All you need to do is purchase a stabilizer.

What it is

A stabilizer is a device that equalizes the voltage in the network by supplying the required 220 volts to the device. Most modern low-cost stabilizers operate in the range of + -10% of the desired indicator, that is, “leveling” surges in the range from 200 to 240 volts. If you are experiencing more serious subsidence, then you need to select a more expensive device - some models are capable of "pulling" the line from 180 volts.

Modern voltage stabilizers this is small devices, which work completely silently, and do not hum like their “ancestors” from the USSR. They can operate on 220 and 380 volts (must be selected when purchasing).

In addition to the voltage drop, high-quality stabilizers “clear” the line from garbage impulses, interference and overloads. We recommend that you definitely use such devices in everyday life, installing them at the entrance to the apartment or, at least, for every important household appliance(boiler, work computer, etc.). But it is still better not to risk expensive equipment, but to purchase a normal leveling device.

Now that you knowthink about how much money it can save you. At the same time, a large number of equipment is working in the apartment - Washer, a computer, a TV, a dishwasher, a phone is charging, etc. If there is a leap, then all this can fail, and the damage will be tens, or even hundreds of thousands of rubles. It is almost impossible to prove in court that the reason for the breakdown of equipment was a power surge, therefore, you will have to pay for repairs and purchase a new one with your own money.

The principle of operation of the stabilizer

Types of stabilizers

On this moment There are three types of stabilizers, which differ from each other according to the principle of alignment:

Digital.
Relay.
Servo drives.

The most practical, convenient and reliable are digital or electronic devices... They work due to the presence of thyristor switches. The main advantage of such systems is the minimum response time, absolute noiselessness, and small size. The disadvantage is the price, they are usually 30-50% more expensive than other devices.

Relay systems belong to the middle price segment. They work by switching power relays, turning on and off the corresponding windings on the transformer. Relay voltage stabilizers for home are considered optimal. The main advantages of the device are affordable prices, fast response speed. Minus - short service life. A conventional relay can withstand about 40-50 thousand switchings, after which the contacts wear out and begin to stick. If you have a fairly stable network, then the relay system will work for you for several years. But if failures happen several times a day, then it can fail in one and a half to two years.

Servo-type devices have a low cost and work by changing the number of turns involved by the transformer. Their switching occurs due to the movement of the servo, which switches the contact, as on a rheostat. The main advantage of these systems is affordable price... The downside is low reliability and long response time.

How to choose the right one

Now you know,for home. Let's consider how to choose the right devices.

First of all, you need to determine how many devices will work at the same time. For example, if you are in the kitchen, turn on the electric kettle, microwave and dishwasher. In the hall there is a TV and a computer, in the bathroom there is a washing machine. At the same time, a refrigerator and an individual heating boiler are working in the apartment without switching off - these devices also consume 200-300 watts.

You can find out the power of devices according to the passport. But be sure to keep in mind that manufacturers indicate active power, not real.

Method of mounting the stabilizer after the meter

Attention:for a correct calculation, it is necessary to know the total capacity of the installation, and not its operating mode. The refrigerator consumes 100 watts per hour during operation, but when starting the engine requires 300-500 watts of reactive energy. Therefore, always take the device with a margin.

For example, the consumption of your apartment is 2000 watts. This is a very real figure for a classic "kopeck piece" with modern technology, and not equipped with powerful consumers such as a boiler, electric oven and hob. To account for full power, add 20%. Also, you should understand that if the network sags by 20 volts, then the transformer loses 20% of its power. As a result, the total stock will reach 30-40%, and you will need to purchase a stabilizer with a capacity of 2000 * 0.4 + 2000 = 2800-watt device.

This is all the information you need to know about voltage regulator: what is it and you now know how it works. It remains to figure out how to connect it correctly. It is recommended to install it immediately behind the meter, before the electrical panel, although it can also be hooked separately to the required lines. The device must be grounded so that in case of problems it will drain the current and protect your equipment. It is better to invite an experienced electrician to connect.

The number of electrical appliances in the homes of citizens is growing every day. If earlier people in the house had a refrigerator and a TV set from electrical devices, today you can count dozens of different elements of digital and household appliances. As a result, the demand for electricity is also growing. At the same time, many people live in old houses that were built 40 or even 50 years ago. But what is a voltage regulator for? It's simple. The wiring in these houses and the power lines to them are designed for low energy consumption by the residents. This means that voltage drops in the power grid cannot be ruled out. Even in large cities, similar problems are observed, while in villages and small settlements the situation is dire.

What is a voltage regulator for?

Household and digital appliances (in most cases) cannot boast of resistance to power surges. Any drop or sharp increase can cause damage to electrical appliances (refrigerators, computers, televisions). By the way, it is household appliances (not digital) that suffer from this problem the most. Large electrical heating devices such as boilers, which are extremely sensitive to voltage stability, fall into a special risk group.

You can avoid such situations by using a special device that can always provide a stable voltage to the home's electrical network. That's what a voltage regulator is for.

Who doesn't need this device?

Not all people need it, because in most cities in Russia, the voltage in the network is stable. It makes no sense to buy this device if 230 V is constantly maintained in the house without any hesitation in any direction. Why do you need a voltage regulator in this case? Even if you install it, then its work for 99% of the time will be useless. Perhaps someday he will save the TV, because in theory, drops in the network are possible.

Who needs it?

However, this thing is really necessary for those people who suffer from unstable electricity in the house. And although in theory it is possible to sue the electricity company and compensate for damage in the event of a breakdown of the refrigerator or other equipment in the house, this is difficult to do. At a minimum, you will have to record the fact of a power surge and prove that the refrigerator burned down precisely because of the poorly provided service.

Benefits of using a stabilizer

Are you still wondering what a voltage regulator is for? When using it:

All electrical appliances in the house will be powered from the network for which they are designed. Consequently, their lifespan will increase and energy consumption will decrease.
All equipment in the house will be protected from power surges, and even if it happens, computers and household appliances will not fail.

Note that powerful devices that are installed at the entrance to the wiring into the house are quite expensive. Sometimes it makes sense to use a cheap and low-power stabilizer that can power only one computer, for example. This solution is often used in private homes and even offices. Also, many users are interested in whether a voltage stabilizer is needed for a gas boiler. If the voltage in the house is unstable, then this device is necessary for the boiler. The boiler automation operates from the mains, and a power surge can damage it. If this happens in winter, the heating system of the house supplied by the boiler will stop. Now you know whether you need a voltage stabilizer for the boiler, but which one is already an actual question.

Varieties of stabilizers

Output voltage stability is achieved different ways... There are dozens of options for schemes to ensure network stability, but not all are effective. At the moment, the following stabilizers are sold in stores:

Stepping devices based on mechanical or solid state relays - they are based on a standard transformer. Everything works simply: current flows to the primary winding, and the output voltage is removed from the secondary winding, the relay switches the voltage between them. Typically, the switching step is 10-15 V, which allows you to correct fluctuations from 5-7%. This is a very weak indicator, but such a scheme is cheap and common. Most of the stabilizers on the market work in this way.
Electromechanical. A transformer is also used here, but instead of a relay, the movement of the brush along the winding is used as a switch of the turns of the secondary winding. These devices are reliable, but more expensive. Moreover, they have a serious drawback - a slow reaction speed. Sharp power surges in the network will simply not have time to be smoothed out.
Ferroresonant - these devices are very expensive and large, so they are almost never used in everyday life. These are the most reliable and accurate units and they are used only where sensitive and expensive equipment is working.
Devices based on double conversion of current. Like ferroresonant stabilizers, these stabilizers are also expensive but effective. Here the alternating current is converted to direct current, after which the direct current is transformed back into alternating current. This allows you to smooth out the smallest fluctuations, as a result of which we get a stable voltage at the output.

What should you choose?

Speaking about which one is needed or other household appliances, we can only recommend choosing electromechanical stabilizers. Stepped are also ok, but they are only effective when the voltage is only slightly unstable. Therefore, it is best to focus on more expensive but effective electromechanical devices. Ferroresonant regulators or double-conversion devices are very expensive and often unavailable.

Conclusion

Now you know which voltage regulator is needed for a refrigerator or other household appliances. Finally, it is appropriate to warn you against low-quality Chinese stabilizers, which only create the appearance of work. It should be understood that this device must be extremely reliable and of high quality, because it depends on how effectively expensive digital and household appliances will work in the house, how long they will last. A stabilizer is a prerequisite for dwellings in which there is a change in the voltage in the power grid at least once a month. You need to complain about this and seek from the company providing electricity to resolve the issue, and in case of damage to the equipment, you even need to sue it. But it is much easier and cheaper to buy a stabilizer.

In discussions electrical circuits the terms "voltage regulator" and "current regulator" are often found. But what's the difference between them? How do these stabilizers work? Which circuit needs an expensive voltage regulator, and where is a simple regulator sufficient? You will find answers to these questions in this article.

Consider a voltage regulator using the example of the LM7805 device. Its characteristics indicate: 5V 1.5A. This means it is precisely the voltage that stabilizes and it is up to 5V. 1.5A is the maximum current that the stabilizer can carry. Peak current. That is, it can give 3 milliamperes, 0.5 amperes, and 1 ampere. As much current as the load requires. But not more than one and a half. This is the main difference between a voltage stabilizer and a current stabilizer.

Types of voltage stabilizers

There are only 2 main types of voltage stabilizers:

linear
impulse

Linear voltage regulators

For example, microcircuits BANK or , LM1117, LM350.

By the way, KREN is not an abbreviation, as many people think. This is an abbreviation. The Soviet stabilizer microcircuit, similar to the LM7805, had the designation KR142EN5A. Well, there is also KR1157EN12V, KR1157EN502, KR1157EN24A and a bunch of others. For brevity, the entire family of microcircuits was called "KREN". KR142EN5A then turns into KREN142.

Soviet stabilizer KR142EN5A. Analogue of LM7805.

Stabilizer LM7805

The most common type. Their disadvantage is that they cannot operate at a voltage lower than the declared output voltage. If it stabilizes the voltage at 5 volts, then it needs at least one and a half volts more to the input. If we apply less than 6.5 V, then the output voltage will "sink" and we will no longer get 5 V. Another disadvantage of linear stabilizers is strong heating under load. Actually, this is the principle of their work - everything that is higher than the stabilized voltage simply turns into heat. If we supply 12 V to the input, then 7 will be spent on heating the case, and 5 will go to the consumer. At the same time, the case heats up so much that without a radiator, the microcircuit will simply burn out. All this leads to another serious drawback - a linear stabilizer should not be used in devices powered by batteries. The energy of the batteries will be spent on heating the stabilizer. Switching stabilizers are devoid of all these disadvantages.

Switching voltage regulators

Pulse stabilizers- are devoid of linear drawbacks, but they are also more expensive. This is no longer just a three-pin chip. They look like a circuit board with parts.

One of the versions of the pulse stabilizer.

Pulse stabilizers there are three types: lowering, increasing and omnivorous. The most interesting are omnivores. Regardless of the voltage at the input, the output will be exactly what we need. The omnivorous impulse does not care if the input voltage is lower or higher than the required one. He automatically switches to the mode of increasing or decreasing the voltage and keeps the set at the output. If the characteristics state that the stabilizer can be supplied from 1 to 15 volts at the input and the output will be stable at 5, then it will be so. In addition, heating pulse stabilizers so insignificant that it can be neglected in most cases. If your circuit will be powered by batteries or placed in a closed case, where strong heating of the linear stabilizer is unacceptable, put a pulse one. I use a penny tunable switching voltage regulator that I order from Aliexpress. You can buy.

Good. What about the current stabilizer?

I won't open America if I say that current stabilizer stabilizes the current.
Current stabilizers are also sometimes called LED drivers. Outwardly, they look like switching voltage regulators. Although the stabilizer itself is a small microcircuit, everything else is needed to ensure the correct operation. But usually the entire circuit is called a driver at once.

This is what a current regulator looks like. The red circle is the same circuit that is the stabilizer. Everything else on the board is strapping.

So. The driver sets the current. Stable! If it is written that the output will have a current of 350mA, then it will be exactly 350mA. But the output voltage can vary depending on the voltage required by the consumer. Let's not indulge in the theory about that. how it all works. Just remember that you do not regulate the voltage, the driver will do everything for you based on the consumer.

Well, why do you need all this?

Now you know how a voltage stabilizer differs from a current stabilizer and you can navigate in their variety. Perhaps you still do not understand why these things are needed.

Example: you want to power 3 LEDs from the vehicle electrical system. As you can learn from, it is important for the LED to control the current strength. We use the most common option for connecting LEDs: 3 LEDs and a resistor are connected in series. The supply voltage is 12 volts.

With a resistor, we limit the current to the LEDs so that they do not burn out. Let the voltage drop across the LED be 3.4 volts.
After the first LED, 12-3.4 = 8.6 volts remains.
We have enough for now.
On the second, another 3.4 volts will be lost, that is, 8.6-3.4 = 5.2 volts will remain.
And enough for the third LED too.
And after the third, 5.2-3.4 = 1.8 volts will remain.
If you want to add a fourth LED, it won't be enough.
If the supply voltage is raised to 15V, then that's enough. But then the resistor will also need to be counted. A resistor is the simplest current stabilizer (limiter). They are often placed on the same tapes and modules. It has a minus - the lower the voltage, the lower the current on the LED will be (Ohm's law, you can't argue with it). This means that if the input voltage is unstable (in cars it usually is), then you first need to stabilize the voltage, and then you can limit the current with the resistor to the required values. If we use a resistor as a current limiter where the voltage is not stable, we need to stabilize the voltage.

It is worth remembering that it makes sense to install resistors only up to a certain current strength. After a certain threshold, the resistors begin to get very hot and you have to install more powerful resistors (why the power resistor is described in this device). Heat dissipation increases, efficiency decreases.

Also called an LED driver. Often, those who are not very versed in this, the voltage regulator is simply called the LED driver, and the switching current regulator is called good LED driver. It immediately delivers a stable voltage and current. And almost does not heat up. This is how it looks:

Many people know what interruptions and power surges are in electrical network... It's one thing when the bulbs just blink from this and can burn out. And another thing is when a washing machine or refrigerator burns out from voltage surges. This will significantly hit the family budget. Imported household appliances are not designed for such voltage surges that often occur in domestic networks. To protect yourself from the risk of malfunctions in home household devices, you need to get a voltage stabilizer, which is selected according to the total power of the devices that will work in your home network.

Varieties

Voltage stabilizers are devices that equalize the supply voltage to those parameters that correspond to standard values, and also clean the voltage from high-frequency interference. The type of stabilizer determines the type of main built-in mechanism that acts as a stabilizer.

Voltage stabilizers are divided into two main types:

Accumulating.
Corrective.

The first type of stabilizers is not currently used, since they are large in size. Previously, they were used in production, and not in a domestic environment. Cumulative voltage stabilizers function by accumulating electrical energy in a container, and then receive from this container the required electric current with the required parameters. Uninterruptible power supplies work on a similar principle.

Corrective stabilizers voltages most often include a control unit. It reacts to voltage drops in one direction or the other, and at the same time connects the corresponding transformer winding. Corrective stabilizers are widely used in domestic conditions.

They, in turn, are divided into several types:

Relay.
Electronic (thyristor).
Ferroresonant.
Electromechanical.
Inverter.
Linear.

Design features and work

The corrective type of stabilizers has become the most popular in everyday life.

Relay voltage stabilizers

They became the most popular due to their low cost and quality of work. The main advantage of relay stabilizers is their speed. They very quickly respond to voltage changes, and return its value to standard limits, thereby protecting household devices.

Of the shortcomings, it can be noted that when the relay is triggered, a sharp voltage jump of 5-15 volts occurs, depending on the manufacturer. For household appliances, such a jump will not have a negative effect, however, the lighting will flicker noticeably. Therefore, when the relay stabilizer is operating, blinking is sometimes observed, while they do not react to it.

As in other types of stabilizer, the main element of the relay model is the control unit on semiconductor elements... The electronic block of the stabilizer is made in the form of a powerful microcontroller that analyzes the voltage at the input and output. As a result, it generates control signals for power relays or switches. The microcontroller, when creating a control voltage, takes into account the response time of the power relays and switches. This makes it possible to carry out switching circuits without breaking them. As a result, the shape of the output voltage graph becomes identical to the input voltage shape.

Electronic voltage stabilizers

Thyristor stabilizers work according to the principle, which is based on automatic switching of different transformer windings with power switches in the form. This principle is similar to the operation of relay devices. The difference between relay stabilizers is that they do not have mechanical contacts, there is large quantity voltage equalization steps and high working accuracy 2-5%.

Electronic appliances do not generate noise in the home as there are no mechanical relays. They are replaced by electronic keys. Thyristor stabilizers work with high efficiency.

At practical application electronic models have proven to be sensitive devices that are negatively affected by overheating. Domestic manufacturers most often produce just this type of stabilizers.

The most serious disadvantage of thyristor models is their high cost. The warranty period for almost all types of stabilizers is within 1-3 years, depending on the manufacturer.

Ferroresonant

Their action is based on a change in the value of the inductance of coils with a metal core, when the current changes. Capacitance C1 is connected in series with the primary winding of the transformer. Together with the primary winding, it forms resonant circuit which is tuned to a mains frequency of 50 hertz.

The size of the capacitor depends on the power of the transformer. With a transformer power of up to 60 watts, a capacitor is used with a value of up to 12 μF. A saturation choke is used to create significant stabilizer power.

With a low mains voltage, a small current flows through the choke, and the inductance of the choke is large. The main part of the current flows through the parallel connected capacitor. In this case, the total resistance of this circuit is of the capacitive type.

The capacitor compensates for some of the inductive reactance of the transformer coil. This increases the coil current. The output voltage of the transformer also increases. This is characteristic of the voltage resonance effect.

As the voltage rises, the inductor current also rises, and its inductance drops. The value of the capacitance is calculated so that resonance occurs in the inductor-capacitor circuit, at which the resistance of this circuit would be the greatest, and the current coming from the power supply to the transformer is the smallest.

With an increase in the mains voltage, the resistance of the circuit increases until the moment of resonance. This makes it possible to stabilize the voltage across the transformer with large voltage drops.

The advantage of ferroresonant devices is reliability and simplicity. The disadvantage is the significant dependence of the voltage at the output of the device on the frequency of the current and the distortion of the voltage waveform. Also, stabilizers with saturated coil cores have high magnetic dissipation. This negatively affects the functioning of the surrounding devices and the person.

Electromechanical voltage stabilizers

The principle of operation of such a device is quite simple. When the voltage drops, graphite brushes move along the coil of the transformer, thereby regulating and adjusting the output voltage.

In the first examples of electromechanical stabilizers, a manual method (switch) was used to move the brushes. The user had to constantly monitor the voltage indicator readings.

In new models of devices, this function is performed automatically by a small motor, which, in case of voltage drops, moves the brush along the transformer winding.

The advantages of such stabilizers are simplicity and reliability of the device, increased efficiency. Among the shortcomings, one can note the low speed of response during voltage drops, as well as the rapid wear of mechanical parts. Therefore, the electromechanical form of the stabilizer requires constant maintenance in the form of control and replacement of brushes.

Inverter voltage stabilizers

They convert direct current into alternating current, and also perform the opposite action, that is, convert alternating current into direct current using a microcontroller and a crystal oscillator.

Among the advantages of inverter stabilizers, one can single out low noise during the operation of the device, compact size and a wide range of input operating voltages, which ranges from 115-290 volts.

The disadvantage of inverter designs is their high cost, unlike many other types of stabilizers.

Linear

Made in the form of a voltage divider. An unstable voltage is applied to the input of such a device, and the equalized voltage comes out from the lower arm of the divider. Alignment is performed by changing the resistance of the voltage divider arm. In this case, the resistance value is maintained such a value at which the output voltage of the device was within certain limits.

With a significant ratio of the values of the output and input voltages, the linear stabilizer has a reduced efficiency, since a significant part of the power is dissipated into heat at the tuning element. Therefore, the voltage regulator is usually mounted on a heat sink to allow heat dissipation.

The advantage of a linear device is the absence of interference, simplicity of design and a small number of parts. The disadvantage is low efficiency, high heat generation.

What to look for when choosing a stabilizer

Mounting method ... It can be wall-mounted, with horizontal or vertical installation (for stationary appliances). It can be installed next to the device for which it was purchased.
Accuracy of work,input and output voltage... This characteristic depends mainly on the parameters of the input voltage. It is better to choose the lowest accuracy rate of the device from 1 to 3%, at a voltage of 220 volts.
Stabilizer power is selected not only by the power of the connected electrical device. A certain power reserve is added to this value. For the entire apartment, this margin should be within 30%.
Power supply phases (single-phase or three-phase network).
Performance (response time to voltage drops), in milliseconds.
Stabilizer protection ... Expensive devices are most often equipped with protective systems that protect the stabilizer from short circuits, sudden changes in voltage and other negative phenomena.
dimensions the device and its noise during operation.
Price... Professionals do not recommend buying cheap Chinese fakes, since you should not skimp on the quality of the stabilizer. A quality device doesn't have to be cheap. It is better to purchase a domestic model, or a European-made device.
Guarantee period plays a big role when choosing any device. If the device is Chinese, then it is unlikely that there will be any guarantee for it. Stabilizers purchased from specialized retail outlets can be exchanged free of charge during the warranty period in the event of a malfunction or defect.

The greatest difficulty is usually caused when choosing a device, its power. In addition to the active component of power, which is consumed by household devices, some of them have. It appears if available (if the device has a powerful electric motor). When it is started, the current increases several times. If you choose a stabilizer without taking into account this reactive power component, then it may not cope with a high load when starting a device with an electric motor.

Another factor that greatly influences the choice of a regulator is the transformation ratio, which is zero if the regulator is operating under ideal conditions. That is, exactly 220 volts are supplied to the input, and exactly the same value comes out to the consumer. And if the regulator has to equalize the voltage, then the power decreases.

Voltage regulator

Voltage regulator- a converter of electrical energy, allowing to obtain the output voltage, which is within the specified limits with significantly large fluctuations in the input voltage and load resistance.

By the type of output voltage, stabilizers are divided into DC and AC stabilizers. Typically, the type of power supply (DC or AC) is the same as the output voltage, although exceptions are possible.

DC stabilizers

Linear stabilizer microcircuit KR1170EN8

Linear stabilizer

A linear stabilizer is a voltage divider, the input of which is supplied with an input (unstable) voltage, and the output (stabilized) voltage is removed from the lower arm of the divider. Stabilization is carried out by changing the resistance of one of the divider arms: the resistance is constantly maintained so that the voltage at the output of the stabilizer is within the specified limits. With a large ratio of input / output voltages, the linear stabilizer has a low efficiency, since most of the power P rac = (U in - U out) * I t is dissipated in the form of heat on the regulating element. Therefore, the regulating element must be able to dissipate sufficient power, that is, it must be installed on a radiator of the required area. The advantage of a linear regulator is simplicity, no interference and few parts used.

Depending on the location of the element with variable resistance, linear stabilizers are divided into two types:

Consistent: the control element is connected in series with the load.
Parallel: the control element is connected in parallel with the load.

Depending on the stabilization method:

Parametric: in such a stabilizer, a section of the I - V characteristic of the device is used, which has a large steepness.
Compensatory: has feedback. In it, the voltage at the output of the stabilizer is compared with the reference one, and a control signal for the regulating element is formed from the difference between them.

Parallel parametric stabilizer on a zener diode

It is used to stabilize voltage in low-current circuits, since for normal work circuits, the current through the Zener diode D1 must be several times (3-10) higher than the current in the stabilized load R L. Often this linear regulator circuit is used as a voltage reference in more complex regulator circuits. To reduce the instability of the output voltage caused by changes in the input voltage, a resistor R V is used instead of. However, this measure does not reduce the output voltage instability caused by the change in load resistance.

Series Bipolar Transistor Regulator

U out = U z - U be.

In fact, this is the parallel parametric stabilizer on a zener diode discussed above, connected to the input of the emitter follower. It has no chains feedback, providing compensation for changes in the output voltage.

Its output voltage is less than the stabilization voltage of the zener diode by the value U be, which practically does not depend on the magnitude of the current flowing through p-n junction, and for devices based on silicon is approximately 0.6V. The dependence of U be on the magnitude of the current and temperature worsens the stability of the output voltage, in comparison with a parallel parametric stabilizer based on a zener diode.

The emitter follower (current amplifier) allows you to increase the maximum output current of the stabilizer, in comparison with a parallel parametric stabilizer on a zener diode, by a factor of β (where β is the current gain of this transistor instance). If this is not enough, a composite transistor is used.

In the absence of load resistance (or at load currents of the microampere range), the output voltage of such a stabilizer (open circuit voltage) increases by 0.6V due to the fact that U be in the microcurrent range becomes close to zero. To overcome this feature, a ballast is connected to the output of the stabilizer pull-up resistor providing a load current of several mA.

Serial compensation stabilizer using an operational amplifier

The part of the output voltage U out taken from the potentiometer R2 is compared with the reference voltage U z at the zener diode D1. The voltage difference is amplified by the operational amplifier U1 and fed to the base of the regulating transistor connected according to the emitter follower circuit. For stable operation of the circuit, the loop phase shift should be close to 180 ° + n * 360 °. Since part of the output voltage U out is fed to the inverting input of the operational amplifier U1, the operational amplifier U1 shifts the phase by 180 °, the regulating transistor is switched on according to the emitter follower circuit, which does not shift the phase. The loop phase shift is 180 °, the phase stability condition is met.

The reference voltage Uz is practically independent of the magnitude of the current flowing through the zener diode, and is equal to the stabilization voltage of the zener diode. To increase its stability with changes in Uin, it is used instead of the resistor R V.

In this stabilizer, the operational amplifier is actually connected in a non-inverting amplifier circuit (with an emitter follower to increase the output current). The ratio of the resistors in the feedback loop sets its gain, which determines how many times the output voltage will be higher than the input voltage (i.e., the reference voltage applied to the non-inverting input of the op-amp). Since the gain of a non-inverting amplifier is always greater than unity, the value of the reference voltage (stabilization voltage of the zener diode) must be selected less than the required minimum output voltage.

The instability of the output voltage of such a stabilizer is almost completely determined by the instability of the reference voltage, due to the large loop gain of modern op amps ( G openloop = 10 5 ÷ 10 6).

To exclude the influence of the instability of the input voltage on the operating mode of the op-amp itself, it can be powered by a stabilized voltage (from additional parametric stabilizers on a zener diode).

Pulse stabilizer

In a switching regulator, the current from an unstabilized external source is supplied to a storage device (usually a capacitor or choke) in short pulses; in this case, energy is stored, which is then released into the load in the form of electrical energy, but, in the case of a choke, already with a different voltage. Stabilization is carried out by controlling the duration of pulses and pauses between them - pulse-width modulation. A switching regulator, in comparison with a linear one, has a significantly higher efficiency. The disadvantage of a switching regulator is the presence of impulse noise in the output voltage.

Unlike a linear regulator, a switching regulator can convert the input voltage in an arbitrary way (depending on the regulator circuit):

Downward below
Raising stabilizer: output stabilized voltage always above input and has the same polarity.
Buck-Buck stabilizer: the output voltage is stabilized, can be as above and below input and has the same polarity. Such a stabilizer is used in cases where the input voltage is slightly different from the required one and can vary, taking a value both higher and lower than the required one.
Inverting stabilizer: the output stabilized voltage has reverse polarity relative to the input, the absolute value of the output voltage can be any.

AC voltage stabilizers

Ferroresonant stabilizers

During the Soviet era, household ferroresonant voltage stabilizers became widespread. Usually, TVs were connected through them. In TVs of the first generations, network power supplies with linear voltage stabilizers were used (and in some circuits they were completely powered by unregulated voltage), which did not always cope with voltage fluctuations in the network, especially in rural areas, which required preliminary voltage stabilization. With the advent of 4UPITST and USTsT TVs, which had switching power supplies, the need for additional stabilization of the mains voltage has disappeared.

The ferroresonant stabilizer consists of two chokes: with an unsaturated core (having a magnetic gap) and a saturated one, as well as a capacitor. The peculiarity of the I - V characteristic of a saturated inductor is that the voltage across it changes little when the current through it changes. By selecting the parameters of the chokes and capacitors, it is possible to ensure voltage stabilization when the input voltage changes within a fairly wide range, but a slight deviation in the frequency of the supply network greatly influenced the characteristics of the stabilizer.

Modern stabilizers

Currently, the main types of stabilizers are:

electrodynamic servo (mechanical)
static (electronic switchable)
relay
compensation (electronic smooth)

The models are produced in both single-phase (220/230 V) and three-phase (380/400 V) versions, their power ranges from several hundred watts to several megawatts. Three-phase models are produced in two modifications: with independent adjustment for each phase or with adjustment for the average-phase voltage at the input of the stabilizer.

The produced models also differ in the allowable range of input voltage variation, which can be, for example, the following: ± 15%, ± 20%, ± 25%, ± 30%, -25% / + 15%, -35% / + 15% or -45% / + 15%. The wider the range (especially in the negative direction), the larger the dimensions of the stabilizer and the higher its cost at the same output power.

An important characteristic of a voltage regulator is its speed, that is, the higher the speed, the faster the regulator will react to changes in the input voltage. Speed is a period of time (milliseconds) during which the regulator is able to change the voltage by one volt. Have different types stabilizers have different speed of response, for example, for electrodynamic ones, the speed is 12 ... 18 ms / V, static stabilizers will provide 2 ms / V, but for electronic, compensation type, this parameter is 0.75 ms / V.

Another important parameter is the accuracy of the output voltage stabilization. According to GOST 13109-97, the maximum permissible deviation of the supply voltage is ± 10% of the nominal. The accuracy of modern voltage regulators ranges from 1% to 8%. An accuracy of 8% is quite enough to ensure the correct operation of the vast majority of household and industrial electrical appliances. More stringent requirements (1%) are usually imposed on the power supply of complex equipment (medical, high-tech, and the like). An important consumer parameter is the ability of the stabilizer to operate at the declared power in the entire input voltage range, but not all stabilizers correspond to this parameter. Some stabilizers can withstand tenfold overloads; when purchasing such a stabilizer, a power reserve is not required.

Literature

Veresov G.P. Power supply for household electronic equipment. - M .: Radio and communication, 1983 .-- 128 p.
V.V. Kitaev and others Power supply for communication devices. - M .: Communication, 1975 .-- 328 p. - 24,000 copies.
V.G. Kostikov Parfenov E.M. Shakhnov V.A. Sources of power supply for electronic devices. Circuitry and design: Textbook for universities. - 2. - M.: Hot line- Telecom, 2001 .-- 344 p. - 3000 copies. - ISBN 5-93517-052-3
Shtilman V.I. Microelectronic voltage stabilizers. - Kiev: Technika, 1976.