Switching power supplies, theory and simple circuits. What is a switching power supply and where is it used?

Almost every electronic device has a power supply - an important element of the wiring diagram. The blocks are used in devices that require low power. The basic task of the power supply is to reduce the mains voltage. The first switching power supplies were designed after the invention of the coil, which worked with alternating current.

The use of transformers gave impetus to the development of power supplies. After the current rectifier, voltage equalization is carried out. In units with a frequency converter, this process takes place differently.

The pulse unit is based on an inverter system. After rectifying the voltage, rectangular pulses with a high frequency are formed and fed to a low-frequency output filter. Pulse blocks power supply converts voltage and supplies power to the load.

There is no energy dissipation from the pulse unit. From the linear source there is dissipation on semiconductors (transistors). Its compactness and light weight also give it superiority over transformer units at the same power, which is why it is often replaced with pulse units.

Operating principle

The operation of a simple design UPS is as follows. If the input current is variable, as most household appliances, then first the voltage is converted to constant. Some unit designs have switches that double the voltage. This is done in order to connect to a network with different voltage ratings, for example, 115 and 230 volts.

The rectifier equalizes the alternating voltage and outputs direct current, which enters the capacitor filter. The current from the rectifier comes out in the form of small pulses of high frequency. The signals have high energy, which reduces the power factor of the pulse transformer. Due to this, the dimensions of the pulse unit are small.

To correct the decrease in power in new power supplies, a circuit is used in which the input current is obtained in the form of a sine. Blocks are installed in computers, video cameras and other devices according to this scheme. The pulse unit operates from a constant voltage passing through the unit without changing. Such a block is called flyback. If it serves 115 V, 163 volts is needed to operate at constant voltage, this is calculated as (115 × √2).

For a rectifier, such a circuit is harmful, since half of the diodes are not used in operation, this causes overheating of the working part of the rectifier. In this case, durability is reduced.

After the mains voltage is rectified, the inverter comes into action and converts the current. After passing through a commutator, which has a high output energy, alternating current is obtained from direct current. With a transformer winding of several tens of turns and a frequency of hundreds of hertz, the power supply works as a low-frequency amplifier; it turns out to be more than 20 kHz, it is not accessible to human hearing. The switch is made using transistors with a multi-stage signal. Such transistors have low resistance and high ability to pass currents.

UPS operation diagram

IN network blocks the input and output are isolated from each other; in pulse blocks, the current is applied to the high-frequency primary winding. The transformer creates the required voltage on the secondary winding.

For output voltages greater than 10 V, silicon diodes are used. At low voltages, Schottky diodes are installed, which have the following advantages:

• Fast recovery, which makes it possible to have small losses.
• Low voltage drop. To reduce the output voltage, a transistor is used; the main part of the voltage is rectified in it.

Minimum size pulse block circuit

In a simple UPS circuit, a choke is used instead of a transformer. These are converters for lowering or increasing voltage, they belong to the most simple class, one switch and throttle are used.

Types of UPS

• A simple UPS based on IR2153, common in Russia.
• Switching power supplies based on TL494.
• Switching power supplies based on UC3842.
• Hybrid type, from energy saving lamp.
• For an amplifier with increased data.
• From electronic ballast.
• Adjustable UPS, mechanical device.
• For UMZCH, highly specialized power supply.
• Powerful UPS with high performance.
• At 200 V - for a voltage of no more than 220 volts.
• 150 watt network UPS, network only.
• For 12 V – works normally at 12 volts.
• For 24 V – works only on 24 volts.
• Bridge – a bridge circuit is used.
• For a tube amplifier - characteristics for tubes.
• For LEDs – high sensitivity.
• Bipolar UPS, distinguished by quality.
• Flyback, has increased voltage and power.

Peculiarities

A simple UPS can consist of small transformers, since as the frequency increases, the efficiency of the transformer is higher and the requirements for core dimensions are smaller. This core is made of ferromagnetic alloys, and steel is used for low frequencies.

The voltage in the power supply is stabilized by negative feedback. The output voltage is maintained at the same level and does not depend on the load and input fluctuations. Feedback is created different methods. If the block has galvanic isolation from the network, then connection of one winding of the transformer is used at the output or using an optocoupler. If decoupling is not needed, then use a simple resistive divider. Due to this, the output voltage is stabilized.

Features of laboratory blocks

The operating principle is based on active voltage conversion. To remove interference, filters are placed at the end and beginning of the circuit. The saturation of the transistors has a positive effect on the diodes, and there is voltage regulation. Built-in protection blocks short circuits. The power cables are used in a non-modular series, the power reaches 500 watts.

The case has a cooling fan, the fan speed is adjustable. The maximum load of the unit is 23 amperes, resistance 3 ohms, maximum frequency 5 hertz.

Application of pulse blocks

The scope of their use is constantly growing both in everyday life and in industrial production.

Switching power supplies are used in uninterruptible power supplies, amplifiers, receivers, televisions, chargers, for low-voltage lighting lines, computer, medical equipment and other various devices and devices for general purposes.

Advantages and disadvantages

The UPS has the following advantages and disadvantages:

• Light weight.
• Increased efficiency.
• Low cost.
• The supply voltage range is wider.
• Built-in safety locks.

The reduced weight and dimensions are due to the use of elements with linear mode cooling radiators and pulse control instead of heavy transformers. The capacitor capacity is reduced by increasing the frequency. The rectification circuit has become simpler; the simplest circuit is half-wave.

Low frequency transformers lose a lot of energy and dissipate heat during transformations. In a UPS, maximum losses occur when transition processes switching At other times, the transistors are stable, they are closed or open. Conditions have been created for energy conservation, efficiency reaches 98%.

The cost of UPS has been reduced due to the unification of a wide range of elements in robotic enterprises. Power elements from controlled switches consist of semiconductors of lower power.

Pulse technologies make it possible to use power networks with different frequencies, which expands the use of power supplies in various energy networks. Semiconductor modules with small dimensions and digital technology are protected against short circuits and other accidents.

Simple units with protection transformers are made on a relay base, on which there is no sense in digital technology. Only in some cases digital technologies are used:

• For control circuits with low power.
• Devices with small current of high-precision control, in measuring technology, voltmeters, energy meters, in metrology.

Flaws

Switching power supplies operate by converting high-frequency pulses and create noise that escapes into the environment. There is a need to suppress and combat interference using different methods. Sometimes noise suppression does not have an effect, and the use of pulse blocks becomes impossible for some types of devices.

It is not recommended to connect switching power supplies both with low and high loads. If the output current suddenly drops below the set limit, starting may not be possible, and the power supply will have data distortions that are not suitable for the operating range.

How to choose switching power supplies

First you need to decide on a list of equipment and divide it into groups:

• Regular consumers without their own energy source.
• Consumers with their source.
• Devices with periodic connection.

In each group, it is necessary to add up the current consumption for all elements. If you get more than 2 A, then it is better to connect several sources.

The second and third groups can be connected to cheap power supplies. Next, we determine the required reservation time. To calculate the battery capacity to provide battery life, the current of equipment of the 1st and 2nd groups is multiplied by hours.

From this figure we select switching power supplies. When purchasing, you cannot neglect the importance of the power supply in the system. The functioning and stability of the equipment depends on it.

They have always been important elements of any electronic devices. These devices are used in amplifiers and receivers. The main function of power supplies is considered to be to reduce the maximum voltage that comes from the network. The first models appeared only after the reel was invented AC.

Additionally, the development of power supplies was influenced by the introduction of transformers into the device circuit. The peculiarity of pulse models is that they use rectifiers. Thus, voltage stabilization in the network is carried out in a slightly different way than in conventional devices where a converter is used.

Power supply device

If we consider regular block power supply, which is used in radio receivers, it consists of a frequency transformer, a transistor, and several diodes. Additionally, the circuit contains a choke. Capacitors are installed with different capacities and their parameters can vary greatly. Rectifiers are usually used of the capacitor type. They belong to the high-voltage category.

Operation of modern blocks

Initially, the voltage is supplied to the bridge rectifier. At this stage, the peak current limiter is activated. This is necessary so that the fuse in the power supply does not burn out. Next, the current passes through the circuit through special filters, where it is converted. Several capacitors are needed to charge the resistors. The unit starts up only after a breakdown of the dinistor. Then the transistor is unlocked in the power supply. This makes it possible to significantly reduce self-oscillations.

When voltage generation occurs, the diodes in the circuit are activated. They are connected to each other using cathodes. A negative potential in the system makes it possible to lock the dinistor. The rectifier start-up is facilitated after the transistor is turned off. In addition, two fuses are provided to prevent saturation of the transistors. They operate in the circuit only after a breakdown. To start feedback, a transformer is required. They feed it in the power supply pulse diodes. At the output, alternating current passes through capacitors.

Features of laboratory blocks

The operating principle of switching power supplies of this type is based on active current conversion. There is one bridge rectifier in the standard circuit. In order to remove all interference, filters are used at the beginning and also at the end of the circuit. The pulsed laboratory power supply has conventional capacitors. Saturation of transistors occurs gradually, and this has a positive effect on diodes. Voltage adjustment is provided in many models. The protection system is designed to save blocks from short circuits. Cables for them are usually used in a non-modular series. In this case, the power of the model can reach up to 500 W.

The power supply connectors in the system are most often installed as ATX 20 type. To cool the unit, a fan is mounted in the case. The speed of rotation of the blades must be adjusted in this case. A laboratory-type unit should be able to withstand the maximum load at 23 A. At the same time, the resistance parameter is maintained on average at 3 ohms. The maximum frequency that a switching laboratory power supply has is 5 Hz.

How to repair devices?

Most often, power supplies suffer due to blown fuses. They are located next to the capacitors. Repair of switching power supplies should begin by removing the protective cover. Next, it is important to inspect the integrity of the microcircuit. If no defects are visible on it, it can be checked using a tester. To remove fuses, you must first disconnect the capacitors. After this they can be removed without any problems.

To check the integrity of this device, inspect its base. Burnt fuses have a dark spot at the bottom, which indicates damage to the module. To replace this element, you need to pay attention to its markings. Then you can purchase a similar product in a radio electronics store. Installation of the fuse is carried out only after fixing the condensates. Another common problem in power supplies is considered to be faults with transformers. They are boxes in which coils are installed.

When very high voltage is applied to the device, they cannot withstand it. As a result, the integrity of the winding is compromised. It is impossible to repair switching power supplies with such a breakdown. In this case, the transformer, like the fuse, can only be replaced.

Network power supplies

Operating principle of switching power supplies network type based on low-frequency reduction of interference amplitude. This happens thanks to the use of high-voltage diodes. Thus, it is more effective to control the limiting frequency. Additionally, it should be noted that transistors are used at medium power. The load on the fuses is minimal.

Resistors are used quite rarely in a standard circuit. This is largely due to the fact that the capacitor is capable of participating in current conversion. The main problem with this type of power supply is the electromagnetic field. If capacitors are used with low capacitance, then the transformer is at risk. In this case, you should be very careful about the power of the device. The network switching power supply has limiters for peak current, and they are located immediately above the rectifiers. Their main task is to control the operating frequency to stabilize the amplitude.

Diodes in this system partially serve as fuses. Only transistors are used to drive the rectifier. The locking process, in turn, is necessary to activate the filters. Capacitors can also be used as isolation type in the system. In this case, the transformer will start up much faster.

Application of microcircuits

A wide variety of microcircuits are used in power supplies. In this situation, much depends on the number of active elements. If more than two diodes are used, the board must be designed for input and output filters. Transformers are also produced different power, and they differ quite a lot in size.

You can solder microcircuits yourself. In this case, you need to calculate the maximum resistance of the resistors taking into account the power of the device. To create an adjustable model, special blocks are used. This type of system is made with double tracks. Ripple inside the board will occur much faster.

Benefits of Regulated Power Supplies

The principle of operation of switching power supplies with regulators is the use of a special controller. This element in the circuit can change the throughput of transistors. Thus, the limiting frequency at the input and output is significantly different. The switching power supply can be configured in different ways. Voltage adjustment is carried out taking into account the type of transformer. Conventional coolers are used to cool the device. The problem with these devices is usually excess current. In order to solve this, protective filters are used.

The power of devices on average fluctuates around 300 W. Only non-modular cables are used in the system. In this way, short circuits can be avoided. Power supply connectors for connecting devices are usually installed in the ATX 14 series. The standard model has two outputs. Rectifiers are used with higher voltage. They can withstand resistance at 3 ohms. In turn, the maximum pulse load adjustable block accepts up to 12 A power supply.

Operation of 12 volt units

Pulse includes two diodes. In this case, filters are installed with a small capacity. In this case, the pulsation process occurs extremely slowly. The average frequency fluctuates around 2 Hz. The efficiency of many models does not exceed 78%. These blocks are also distinguished by their compactness. This is due to the fact that transformers are installed with low power. They do not require refrigeration.

The 12V switching power supply circuit additionally involves the use of resistors marked P23. They can withstand only 2 ohms of resistance, but this is enough power for a device. A 12V switching power supply is used most often for lamps.

How does the TV box work?

The operating principle of switching power supplies of this type is the use of film filters. These devices are able to cope with interference of various amplitudes. Their choke winding is synthetic. Thus, high-quality protection of important components is ensured. All gaskets in the power supply are insulated on all sides.

The transformer, in turn, has a separate cooler for cooling. For ease of use, it is usually set to silent. These devices can withstand maximum temperatures of up to 60 degrees. The operating frequency of the TV switching power supply is maintained at 33 Hz. At subzero temperatures, these devices can also be used, but much in this situation depends on the type of condensates used and the cross-section of the magnetic circuit.

Models of 24 volt devices

In 24-volt models, low-frequency rectifiers are used. Only two diodes can successfully cope with interference. The efficiency of such devices can reach up to 60%. Regulators are rarely installed on power supplies. The operating frequency of the models does not exceed 23 Hz on average. Resistors can only withstand 2 ohms. Transistors in models are installed with the marking PR2.

To stabilize the voltage, resistors are not used in the circuit. The 24V switching power supply filters are of the capacitor type. In some cases, dividing species can be found. They are necessary to limit the maximum frequency of the current. To quickly start a rectifier, dinistors are used quite rarely. The negative potential of the device is removed using the cathode. At the output, the current is stabilized by blocking the rectifier.

Power sides on diagram DA1

Power supplies of this type differ from other devices in that they can withstand heavy load. There is only one capacitor in the standard circuit. For normal operation of the power supply, the regulator is used. The controller is installed directly next to the resistor. No more than three diodes can be found in the circuit.

The direct reverse conversion process begins in the dinistor. To start the unlocking mechanism, a special throttle is provided in the system. Waves with large amplitude are damped by the capacitor. It is usually installed of the dividing type. Fuses are rarely found in a standard circuit. This is justified by the fact that the maximum temperature in the transformer does not exceed 50 degrees. Thus, the ballast choke copes with its tasks independently.

Models of devices with DA2 chips

Switching power supply microcircuits of this type are distinguished from other devices by their increased resistance. They are used mainly for measuring instruments. An example is an oscilloscope that shows fluctuations. Voltage stabilization is very important for him. As a result, the device's readings will be more accurate.

Many models are not equipped with regulators. Filters are mainly double-sided. At the output of the circuit, transistors are installed as usual. All this makes it possible to withstand a maximum load of 30 A. In turn, the maximum frequency indicator is at around 23 Hz.

Blocks with installed DA3 chips

This microcircuit allows you to install not only a regulator, but also a controller that monitors fluctuations in the network. The resistance of the transistors in the device can withstand approximately 3 ohms. The powerful switching power supply DA3 can handle a load of 4 A. You can connect fans to cool the rectifiers. As a result, the devices can be used at any temperature. Another advantage is the presence of three filters.

Two of them are installed at the input under the capacitors. One separating type filter is available at the output and stabilizes the voltage that comes from the resistor. There are no more than two diodes in a standard circuit. However, a lot depends on the manufacturer, and this should be taken into account. The main problem with power supplies of this type is that they are not able to cope with low-frequency interference. As a result, it is impractical to install them on measuring instruments.

How does the VD1 diode block work?

These blocks are designed to support up to three devices. They have three-way regulators. Communication cables are installed only non-modular ones. Thus, current conversion occurs quickly. Rectifiers in many models are installed in the KKT2 series.

They differ in that they can transfer energy from the capacitor to the winding. As a result, the load from the filters is partially removed. The performance of such devices is quite high. At temperatures above 50 degrees they can also be used.

6) I plan to implement the power transformer on an Epcos core of type ETD44/22/15 made of N95 material. Perhaps my choice will change further when I calculate the winding data and overall power.

7) I hesitated for a long time between choosing the type of rectifier on the secondary winding between a dual Schottky diode and a synchronous rectifier. You can install a dual Schottky diode, but this is P = 0.6V * 40A = 24 W in heat, with a SMPS power of approximately 650 W, a loss of 4% is obtained! When using the most common IRF3205 in a synchronous rectifier, the heat channel resistance will be released P = 0.008 Ohm * 40A * 40A = 12.8 W. It turns out we win 2 times or 2% efficiency! Everything was fine until I assembled a solution based on IR11688S on a breadboard. Dynamic switching losses were added to the static losses on the channel, and in the end that’s what happened. The capacity of field workers for high currents is still large. This can be treated with drivers like HCPL3120, but this increases the price of the product and excessively complicates the circuit design. Actually, for these reasons, it was decided to install a double Schottky and sleep peacefully.

8) The LC circuit at the output, firstly, will reduce current ripple, and secondly, it will allow you to “cut off” all harmonics. The last problem is extremely relevant when powering devices operating in the radio frequency range and incorporating high-frequency analog circuits. In our case, we are talking about an HF transceiver, so a filter is simply vital here, otherwise the interference will “crawl” into the air. Ideally, you can also install a linear stabilizer at the output and get minimal ripples of units of mV, but in reality, the speed of the OS will allow you to get voltage ripples within 20-30 mV even without a “boiler”; inside the transceiver, critical nodes are powered through their LDOs, so its redundancy is obvious.

Well, we went over the functionality and this is just the beginning)) But it’s okay, then it will go more vigorously because the most interesting part begins - the calculations of everything!

Calculation of a power transformer for a half-bridge voltage converter

Based on these inputs, let’s calculate our transformer. I have several sets of ETD44/22/15 in stock and therefore I’m focusing on it for now, The list of source data is as follows:

1) N95 material;
2) Core type ETD44/22/15;
3) Operating frequency - 100 kHz;
4) Output voltage - 15V;
5) Output current - 40A.

To calculate transformers up to 5 kW, I use the “Old Man” program, it is convenient and calculates quite accurately. After 5 kW, the magic begins, the frequencies increase to reduce the size, and the field and current densities reach such values ​​that even the skin effect can change the parameters almost 2 times, so for high powers I use the old-fashioned method “with formulas and drawing in pencil on paper." By entering your input data into the program, the following result was obtained:

Figure 2 - Result of calculation of a transformer for a half-bridge

The figure on the left side shows the input data, which I described above. In the center, the results that interest us most are highlighted in purple. I'll go over them briefly:

1) The input voltage is 380V DC, it is stabilized, because The half-bridge is powered by the PFC. Such power simplifies the design of many components, because Current ripple is minimal and the transformer does not have to draw voltage when the input mains voltage is 140V.

2) The power consumed (pumped through the core) turned out to be 600 W, which is 2 times less than the overall power (the amount that the core can pump without going into saturation), which means everything is good. I didn’t find the N95 material in the program, but on the Epcos website in the datasheet I noticed that N87 and N95 will give very similar results, checking on the piece of paper I found out that the difference of 50 W in overall power is not a terrible error.

3) Data on the primary winding: we wind 21 turns into 2 wires with a diameter of 0.8 mm, I think everything is clear here? The current density is about 8A/mm2, which means that the windings will not overheat - everything is fine.

4) Data on the secondary winding: we wind 2 windings of 2 turns each with the same 0.8 mm wire, but already at 14 - still the current is 40A! Next, we connect the beginning of one winding and the end of the other, I will explain how to do this later, for some reason people often fall into a stupor during assembly at this moment. There seems to be no magic here either.

5) The inductance of the output choke is 4.9 μH, the current is 40A, respectively. We need it so that there are no huge current ripples at the output of our block. During the debugging process, I will show on an oscilloscope how to work with and without it, everything will become clear.

The calculation took 5 minutes, if anyone has questions, ask in the comments or PM - I’ll tell you. To avoid searching for the program itself, I suggest downloading it from the cloud using the link. And my deep gratitude to the Old Man for his work!

The next logical step will be to calculate the output choke for the half-bridge, this is exactly the one at 4.9 μH.

Calculation of winding parameters for the output choke

1) Inductance - 4.9 µH;
2) Rated current - 40A;
3) Amplitude before the throttle - 18V;
4) Voltage after the inductor - 15V.

We also use the program from the Old Man (all of them are in the link above) and get the following data:

Figure 3 - Calculated data for winding the output choke

Now let's look at the results:

2) Maximum induction, this is a value that cannot be exceeded, otherwise the magnetic field will saturate the core and everything will be very bad. This parameter depends on the material and its overall dimensions. For modern atomized iron cores, a typical value is 0.5-0.55 T;

3) Winding data: 9 turns are wound with an oblique of 10 strands of wire with a diameter of 0.8 mm. The program even approximately indicates how many layers will be needed for this. I will wind with 9 cores, because... then it will be convenient to divide the large braid into 3 “braids” of 3 wires each and solder them on the board without any problems;

4) Actually, the ring itself on which I will wind it has dimensions of 40/24/14.5 mm, it is enough with a reserve. Material No. 52, I think many have seen yellow-blue rings in ATX blocks; they are often used in group stabilization chokes (GSC).

Calculation of the standby power supply transformer

Let's adjust our input data a little, what do we need:

We get the need for a power supply with total power - 2*15W + 1.5W + 15W = 46.5 W. This is normal power for TOP227, I use it in small SMPS up to 75 W for all sorts of battery charging, screwdrivers and other rubbish, for many years it’s strange that not a single one has burned out yet.

Let's go to another Old Man program and calculate the transformer for flyback:

Figure 4 - Calculation data for standby power transformer

1) The choice of core is justified simply - I have it in the amount of a box and it draws the same 75 W)) Data on the core. It is made of N87 material and has a gap of 0.2 mm on each half or 0.4 mm so-called full gap. This core is directly intended for chokes, and for flyback converters this inductance is precisely a choke, but I won’t get into the weeds just yet. If there was no gap in the half-bridge transformer, then it is required for the flyback converter, otherwise, like any inductor, it will simply go into saturation without a gap.

2) Data about the 700V drain-source switch and 2.7 Ohm channel resistance are taken from the datasheet on TOP227; this controller has a power switch built into the microcircuit itself.

3) I took the minimum input voltage a little with a margin - 160V, this was done so that if the power supply itself is turned off, the duty and indication will remain in operation, they will report an abnormally low supply voltage.

4) Our primary winding consists of 45 turns of 0.335 mm wire in one core. The secondary power windings have 4 turns and 4 cores with a wire of 0.335 mm (diameter), the self-supply winding has the same parameters, so everything is the same, only 1 core, because the current is an order of magnitude lower.

Calculation of the power choke of the active power corrector

We select the program for calculation - PFC_ring (PFC is KKM in Basurmanian), we use the following inputs:

1) Input supply voltage - 140 - 265V;
2) Rated power - 600 W;
3) Output voltage - 380V DC;
4) Operating frequency - 100 kHz, due to the choice of PWM controller.

Figure 5 - Calculation of the power choke of an active PFC

1) On the left, as usual, we enter the initial data, setting 140V as the minimum threshold, we get a block that can operate at a mains voltage of 140V, so we get a “built-in voltage stabilizer”;

The circuitry of the power part and control is quite standard; if you have any questions, feel free to ask in the comments or in private messages. I will try to answer and explain to everyone if possible.

Switching power supply PCB design

The board design process itself does not contain any pitfalls; they are contained in the device for which it is intended. In fact, power electronics does not put forward any wild number of rules and requirements against the background of the same microwave analogue or high-speed digital data buses.

I will list the basic requirements and rules relating specifically to power circuitry, this will allow 99% of amateur designs to be implemented. I won’t tell you about the nuances and “tricks” - everyone must get their own chops, gain experience and then operate with it. And so we went:

A little about current density in printed conductors

People often don’t think about this parameter, and I’ve come across situations where the power section is made with 0.6 mm conductors and 80% of the board area is simply empty. Why do this is a mystery to me personally.

So what current density can be taken into account? For a regular wire, the standard figure is 10A/mm 2, this limitation is tied to the cooling of the wire. You can pass more current, but first put it in liquid nitrogen. Flat conductors, like those on a printed circuit board, for example, have a larger surface area, which makes them easier to cool, which means you can afford higher current densities. For normal conditions with passive or air cooled it is customary to take into account 35-50 A/mm 2, where 35 is for passive cooling, 50 is in the presence of artificial air circulation (my case). There is another figure - 125 A/mm 2, this is a really big figure, not all superconductors can afford it, but it is only achievable with submersible liquid cooling.

I came across the latter while working with a company involved in engineering communications and server design; it was the design that fell to my lot motherboard, namely the part with multi-phase power supply and switching. I was very surprised when I saw a current density of 125 A/mm 2, but they explained this possibility to me and showed me this possibility at the stand - then I understood why entire racks of servers are immersed in huge pools of oil)))

In my piece of hardware everything is simpler, 50 A/mm 2 is quite an adequate figure, with a copper thickness of 35 microns, the polygons will provide the required cross-section without any problems. The rest was for general development and understanding the issue.

3) The gap between the conductors - it is necessary to reduce leakage currents, especially for conductors where an RF signal (PWM) flows, because the field in the conductors arises strongly and the RF signal, due to the skin effect, tends to escape both onto the surface of the conductor and beyond its limits. Usually a gap of 2-3 mm is sufficient;

4) Galvanic isolation gap is the gap between galvanically isolated sections of the board, usually the breakdown requirement is about 5 kV. To break through 1 mm of air you need about 1-1.2 kV, but in our case breakdown is possible not only through air, but also through PCB and a mask. In the factory, materials that undergo electrical testing are used and you can sleep peacefully. Therefore, the main problem is air and from the conditions described above we can conclude that about 5-6 mm of clearance will be sufficient. Basically, the separation of polygons under the transformer, because it is the main means of galvanic isolation.

Now let's move directly to the design of the board, I won't go into super detail in this article, and in general I don't have much desire to write a whole book of text. If there is a large group of people interested (I’ll do a survey at the end), then I’ll just make videos on the “wiring” of this device, it will be faster and more informative.

Stages of creating a printed circuit board:

1) First of all, you need to decide on the approximate dimensions of the device. If you have a ready-made case, then you should measure the seat in it and base the board dimensions on this. I plan to make a custom-made case from aluminum or brass, so I will try to make the most compact device possible without losing quality and performance characteristics.

Figure 9 - Creating a blank for the future board

Remember - the dimensions of the board must be a multiple of 1 mm! Or at least 0.5 mm, otherwise you will still remember my testament from Lenin when you assemble everything into a panel and make preparations for production, and the designers who will create a case for your board will shower you with curses. There is no need to create a board with dimensions ala “208.625 mm” unless absolutely necessary!
P.S. thanks comrade Lunkov for the fact that he still conveyed this bright thought to me))

Here I did 4 operations:

A) I made the board itself with overall dimensions of 250x150 mm. While this is an approximate size, then I think it will shrink noticeably;
b) Rounded the corners, because during the delivery and assembly process, the sharp ones will be killed and wrinkled + the board looks nicer;
c) Placed mounting holes, not metallized, with a hole diameter of 3 mm for standard fasteners and racks;
d) Created a class “NPTH”, in which I defined all non-plated holes and created a rule for it, creating a gap of 0.4 mm between all other components and components of the class. This is Rezonit’s technological requirement for the standard accuracy class (4th).

Figure 10 - Creating a rule for non-plated holes

2) The next step it is necessary to arrange the components taking into account all the requirements; it should already be very close to the final version, because Most of the time, the final dimensions of the board and its form factor will now be determined.

Figure 11 - Primary arrangement of components has been completed

I installed the main components, they will most likely not move, and therefore the overall dimensions of the board were finally determined - 220 x 150 mm. The free space on the board is left for a reason; control modules and other small SMD components will be placed there. To reduce the cost of the board and ease of installation, all components will be only on the top layer, and accordingly there will be only one silk-screen printing layer.

Figure 13 - 3D view of the board after arranging the components

3) Now, having determined the location and general structure We arrange the remaining components and “separate” the board. The board design can be done in two ways: manually and using an autorouter, having previously described its actions with a couple of dozen rules. Both methods are good, but I will still make this board by hand, because... There are few components and there are no special requirements for line alignment and signal integrity and there should not be any. This will definitely be faster, autorouting is good when there are a lot of components (from 500 onwards) and the main part of the circuit is digital. Although if anyone is interested, I can show you how to “separate” the boards automatically in 2 minutes. True, before that you will have to write the rules all day, heh.

After 3-4 hours of “witchcraft” (half of the time I drew the missing models) with the temperature and a cup of tea, I finally wired the board. I didn’t even think about saving space; many will say that the dimensions could have been reduced by 20-30% and they would be right. I have a one-piece copy and wasting my time, which is clearly more expensive than 1 dm2 for a two-layer board, was simply a pity. Speaking of the price of the board - when ordering from Rezonit, 1 dm 2 of a standard class two-layer board costs about 180-200 rubles, so you can’t save much here unless you have a batch of 500+ pieces, of course. Based on this, I can advise - do not be perverted with reducing the area if it is class 4 and there are no requirements for dimensions. And this is the output:

Figure 14 - Board design for a switching power supply

In the future, I will design a case for this device and I need to know its full dimensions, as well as be able to “try on” it inside the case so that at the final stage it does not become clear, for example, that the main board is interfering with the connectors on the case or the display. To do this, I always try to draw all the components in 3D form, the output is this result and a file in .step format for my Autodesk Inventor:

Figure 15 - Three-dimensional view of the resulting device

Figure 16 - Three-dimensional view of the device (top view)

The documentation is now ready. Now I need to create the necessary package of files to order components, I have all the settings already registered in Altium, so everything is uploaded with one button. We need Gerber files and an NC Drill file, the first one stores information about the layers, and the second one stores drilling coordinates. You can view the file for downloading documentation at the end of the article in the project; it all looks something like this:

Figure 17 - Formation of a package of documentation for an order printed circuit boards

Once the files are ready, you can order the boards. I won’t recommend specific manufacturers; there are probably better and cheaper ones for prototypes. I order all boards of the standard class 2,4,6 layers from Rezonit, where I order 2 and 4-layer boards of the 5th class. Class 5 boards, where there are 6-24 layers in China (for example, pcbway), but HDI and class 5 boards with 24 or more layers are already only in Taiwan, after all, the quality in China is still lame, and where the price tag is not lame not so nice. It's all about prototypes!

Following my convictions, I go to Rezonit, oh, how many nerves they frayed and how much blood they drank... but recently they seem to have corrected themselves and began to work more adequately, albeit with kicks. I place orders through my personal account, enter payment details, upload files and send. Personal account I like theirs, by the way, they immediately calculate the price and by changing the parameters you can achieve a better price without losing quality.

For example, now I wanted a board on 2 mm PCB with 35 micron copper, but it turned out that this option is 2.5 times more expensive than the option with 1.5 mm PCB and 35 micron - so I chose the latter. To increase the rigidity of the board, I added additional holes for the stands - the problem was solved, the price was optimized. By the way, if the board went into series, then somewhere around 100 pieces this 2.5-fold difference disappeared and the prices became equal, because then they bought a non-standard sheet for us and spent it without any leftovers.

Figure 18 - Final view of board cost calculation

The final cost is determined: 3618 rubles. Of these, 2100 is preparation, it is paid only once per project, all subsequent repetitions of the order proceed without it and you will pay only for the area. In this case, 759 rubles for a board with an area of ​​3.3 dm2, the larger the series, the lower the cost will be, although now it is 230 rubles/dm2, which is quite acceptable. Of course, it was possible to do urgent production, but I order often, I work with one manager, and the girl always tries to push the order through faster if the production is not busy - in the end, even with the “small series” option, the turnaround time is 5-6 days, it’s enough just to communicate politely and don't be rude to people. And I’m in no hurry, so I decided to save about 40%, which is at least nice.

Epilogue

As promised, I share the source code of the project and other products of our activity:

1) Project source in Altium Designer 16 - ;
2) Files for ordering printed circuit boards - . What if you want to repeat and order, for example, from China, this archive is more than enough;
3) Device diagram in pdf - . For those who do not want to spend time installing Altium from a phone or for review (high quality);
4) Again, for those who do not want to install heavy software, but are interested in twirling the hardware, I am posting a 3D model in pdf - . To view, you must download the file when you open it in the right top corner Click “trust the document only once”, then click on the center of the file and white screen turns into a model.

I would also like to ask the opinion of readers... Now the boards have been ordered, components too - in fact, there are 2 weeks, what should I write an article about? In addition to such “mutants” like this, sometimes you want to sculpt something miniature but useful, I presented several options in the polls, or perhaps suggest your option in a private message, so as not to clutter up the comments.

Only registered users can participate in the survey. Please sign in.

Technical progress does not stand still, and today transformer-type power supplies have been replaced by switching units. There are many reasons for this, but the most important are:

• Simplicity and low cost of production;
• Ease of use;
• Compact and significantly comfortable overall dimensions.

Read the guide on how to choose a hidden wiring detector and how to use it.

From a technical point of view, a switching power supply is a device that rectifies the mains voltage and then forms a pulse from it with frequency response at 10 kHz. It is worth noting that the efficiency of this technical device reaches 80%.

Operating principle

In fact, the entire principle of operation of a switching power supply boils down to the fact that a device of this type is aimed at rectifying the voltage that is supplied to it when connected to the network and then forming a working pulse, due to which this electrical unit can function.

Many people wonder what are the main differences between a pulse device and a regular one? It all comes down to the fact that it has improved technical characteristics and smaller overall dimensions. Also, the pulse unit provides more energy than its standard version.

Species

At the moment, on the territory of the Russian Federation, if necessary, you can find switching power supplies of the following varieties and categories:

• Downtime on IR2153 - this modification is the most popular among domestic consumers;
• On TL494
• On UC3842
• From an energy-saving lamp - it is something like a modified technical device of a hybrid type;
• For an amplifier – it has high technical characteristics;
• From the electronic ballast - it is clear from the name that the device is based on the operation of an electronic type balance. Read the review of what types of LED lamps there are for the home and how to choose.
• Adjustable - this type of mechanical unit can be configured and adjusted on its own;
• For UMZCH - has a narrow specific application;
• Powerful – has high power characteristics;
• 200 volts - this type of device is designed for a maximum voltage of 220V;
• Network 150 W – works only from the network, maximum power – 150 W;
• 12 V – a technical device that can function normally at a voltage of 12 V;
• 24 V – normal operation device is only possible at 24 V
• Bridge – during assembly, a bridge connection scheme was used;
• For a tube amplifier - all technical specifications are designed to work with a tube amplifier;
• For LEDs – has high sensitivity, used for working with LEDs;
• Bipolar has double polarity, the device meets high quality standards;
• Flyback - focused on reverse operation, has high power and voltage ratings.

Scheme

All switching type power supplies depending on the scope of operation and technical features have different schemes:

• 12 V - is the standard option for assembling a system of this type;
• 2000 W - this circuit is intended only for high-power technical devices;
• For an 18 V screwdriver, the circuit is specific and requires special knowledge from the master during assembly;
• For a tube amplifier - in this case we are talking about a simple schematic design, which, among other things, takes into account the output to the tube amplifier;
• For laptops - requires the presence of a special system of protection against voltage surges;
• On the Top 200 - the technical characteristics of the device will be 40 V and 3 A. Read about the design of the alternator.
• On the TL494, the circuit takes into account current limitation and input voltage regulation;
• On UC3845 – assemble the block switching power supply according to this scheme it will not be difficult;
• switching power supply based on ir2153 circuit - applicable for low-frequency amplifiers;
• On the LNK364PN chip – implemented on the basis of the microcircuit design of UC 3842;
• On field effect transistor It’s already clear from the name that this circuit is applicable to a field-effect transistor;
• The circuit of a forward-mode switching power supply is simple in design and does not require special skills during assembly.

Repair



• Introduction
• Conclusion

Introduction

Switching power supplies are now confidently replacing outdated linear ones. Reason - inherent in these power sources high performance, compactness and improved stabilization performance.

With the rapid changes that the principles of power supply for electronic equipment have undergone recently, information on the calculation, construction and use of switching power supplies is becoming increasingly relevant.

Recently, switching power supplies have gained particular popularity among specialists in the field of electronics and radio engineering, as well as in industrial production. There has been a tendency to abandon standard bulky transformer units and switch to small-sized designs of switching power supplies, voltage converters, converters, and inverters.

In general, the topic of switching power supplies is quite relevant and interesting, and is one of the most important areas power electronics. This area of ​​electronics is promising and rapidly developing. And its main goal is to develop powerful power devices that meet modern requirements for reliability, quality, durability, minimizing weight, size, energy and material consumption. It should be noted that almost all modern electronics, including all kinds of computers, audio, video equipment and others modern devices It is powered by compact switching power supplies, which once again confirms the relevance of further development of this area of ​​power supplies.

1. Operating principle of switching power supplies

The switching power supply is an inverter system. In switching power supplies, the AC input voltage is first rectified. Received constant voltage converted to rectangular pulses increased frequency and a certain duty cycle, either supplied to a transformer (in the case of pulse power supplies with galvanic isolation from the supply network) or directly to the output low-pass filter (in pulse power supplies without galvanic isolation). In pulse power supplies, small-sized transformers can be used - this is explained by the fact that with increasing frequency, the efficiency of the transformer increases and the requirements for the dimensions (section) of the core required to transmit equivalent power decrease. In most cases, such a core can be made of ferromagnetic materials, in contrast to the cores of low-frequency transformers, for which electrical steel is used.

Figure 1 - Block diagram switching power supply

The mains voltage is supplied to the rectifier, after which it is smoothed by a capacitive filter. From the filter capacitor, the voltage of which increases, the rectified voltage through the transformer winding is supplied to the collector of the transistor, which acts as a switch. The control device ensures periodic switching on and off of the transistor. To reliably start the power supply, a master oscillator made on a microcircuit is used. The pulses are supplied to the base of the key transistor and cause the start of the autogenerator operating cycle. The control device is responsible for monitoring the output voltage level, generating an error signal and, often, directly controlling the key. The master oscillator microcircuit is powered by a chain of resistors directly from the input of the storage capacitor, stabilizing the voltage with the reference capacitance. The master oscillator and the key transistor of the secondary circuit are responsible for the operation of the optocoupler. The more open the transistors responsible for the operation of the optocoupler, the smaller the amplitude of the feedback pulses, the sooner the power transistor will turn off and the less energy will accumulate in the transformer, which will stop the increase in voltage at the output of the source. The operating mode of the power supply has arrived, where an important role is played by the optocoupler, as a regulator and manager of the output voltages.

The specification of an industrial power supply is more stringent than that of a regular household power supply. This is expressed not only in the fact that there is a high voltage at the input of the power source three phase voltage, but also that industrial power supplies must remain operational even with a significant deviation of the input voltage from the nominal value, including voltage dips and surges, as well as the loss of one or more phases.

Figure 2 - Schematic diagram of a switching power supply.

The scheme works as follows. Three-phase input can be made via three-wire, four-wire circuit or even single-phase. The three-phase rectifier consists of diodes D1 - D8.

Resistors R1 - R4 provide surge protection. The use of protective resistors with overload tripping makes the use of separate fuse links unnecessary. The input rectified voltage is filtered by a U-shaped filter consisting of C5, C6, C7, C8 and L1.

Resistors R13 and R15 equalize the voltage across the input filter capacitors.

When the MOSFET of the U1 chip opens, the source potential of Q1 decreases, the gate current is provided by resistors R6, R7 and R8, respectively, the capacitance of the transitions VR1 ... VR3 unlocks Q1. Zener diode VR4 limits the source-gate voltage applied to Q1. When MOSFET U1 turns off, the drain voltage is limited to 450 volts by the limiter circuit VR1, VR2, VR3. Any additional voltage at the end of the winding will be dissipated by Q1. This connection effectively distributes the total rectified voltage across Q1 and U1.

The absorption circuit VR5, D9, R10 absorbs the excess voltage on the primary winding resulting from the induction leakage of the transformer during the reverse stroke.

Output rectification is carried out by diode D1. C2 - output filter. L2 and C3 form the second filter stage to reduce output voltage instability.

VR6 begins to conduct when the output voltage exceeds the drop across VR6 and the optocoupler. A change in the output voltage causes a change in the current flowing through the optocoupler diode U2, which in turn causes a change in the current through the optocoupler transistor U2. When this current exceeds the threshold at the FB pin of U1, the next duty cycle is skipped. The specified level of output voltage is maintained by regulating the number of missed and completed work cycles. Once the duty cycle has begun, it will end when the current through U1 reaches the set internal limit. R11 limits the current through the optocoupler and sets the feedback gain. Resistor R12 provides bias to VR6.

This circuit is protected from feedback loop breakage, output short circuit, and overload thanks to the functions built into U1 (LNK304). Since the microcircuit is powered directly from its drain pin, a separate power winding is not required.

In switching power supplies, voltage stabilization is ensured through negative feedback. Feedback allows you to maintain the output voltage at a relatively constant level, regardless of fluctuations in the input voltage and load size. Feedback can be organized in different ways. In the case of pulsed sources with galvanic isolation from the supply network, the most common methods are to use communication through one of the output windings of the transformer or using an optocoupler. Depending on the magnitude of the feedback signal (depending on the output voltage), the duty cycle of the pulses at the output of the PWM controller changes. If decoupling is not required, then, as a rule, a simple resistive voltage divider is used. Thus, the power supply maintains a stable output voltage.

2. Basic parameters and characteristics of switching power supplies

Classification of switching power supplies (SMPS) is made according to several main criteria:

By type of input and output voltage;

According to typology;

According to the shape of the output voltage;

By type of supply circuit;

By load voltage;

By load power;

By type of load current;

By number of exits;

In terms of voltage stability across the load.

By type of input and output voltage

1. AC/DC are converters AC voltage to permanent. Such converters are used in a wide variety of areas - industrial automation, telecommunications equipment, instrumentation equipment, industrial data processing equipment, security equipment, as well as special-purpose equipment.

2. DC/DC are DC/DC converters. Such DC/DC converters use pulse transformers with two or more windings, and there is no connection between the input and output circuits. Pulse transformers have a large potential difference between the input and output of the converter. An example of their application could be a power supply unit (PSU) for pulsed photo flashes with an output voltage of about 400 V.

3. DC/AC are DC-AC converters (inverter). The main area of ​​application of inverters is work in rolling stock of railway and other vehicles that have an on-board DC power supply network. They can also be used as main converters as part of backup power supplies.

High overload capacity allows powering a wide range of devices and equipment, including capacitor compressor motors refrigeration units and air conditioners.

By typology IIPs are classified as follows:

flyback converters;

forward pulse converters (forwardconverter);

converters with push-pull output;

converters with half-bridge output (halfbridgeconverter);

converters with bridge output (fullfbridgeconverter).

According to the output voltage shape IIPs are classified as follows:

1. With modified sine wave

2. With a sinusoid of the correct shape.

Figure 3 - Output waveforms

By type of supply circuit:

SMPS that use electrical energy obtained from a single-phase alternating current network;

SMPS that use electrical energy obtained from a three-phase alternating current network;

SMPS using electrical energy from an autonomous source DC.

By load voltage:

By load power:

Low power SMPS (up to 100 W);

Medium power SMPS (from 100 to 1000 W);

High power SMPS (over 1000 W).

By type of load current:

SMPS with AC output;

SMPS with DC output;

SMPS with AC and DC output.

By number of outputs:

single-channel SMPS having one DC or AC output;

multi-channel SMPS having two or more output voltages.

In terms of voltage stability across the load:

stabilized SMPS;

unstabilized SMPS.

3. Basic methods of constructing switching power supplies

The figure below will show appearance switching power supply.

Figure 4 - Switching power supply

So, to begin with, let us outline in general terms what main modules are in any switching power supply unit. In a typical version, a switching power supply can be divided into three functional parts. This:

1. PWM controller (PWM), on the basis of which a master oscillator is assembled, usually with a frequency of about 30...60 kHz;

2. A cascade of power switches, the role of which can be performed by powerful bipolar, field-effect or IGBT (insulated gate bipolar) transistors; this power stage may include an additional control circuit for these same switches using integrated drivers or low-power transistors; The circuit for connecting power switches is also important: bridge (full bridge), half bridge (half bridge) or with a midpoint (push-pull);

3. Pulse transformer with primary (s) and secondary (s) winding (s) and, accordingly, rectifier diodes, filters, stabilizers, etc. at the exit; ferrite or alsifer is usually chosen as the core; in general, those magnetic materials that are capable of operating at high frequencies (in some cases above 100 kHz).

There are three main ways to construct pulsed power supplies (see Fig. 3): step-up (the output voltage is higher than the input voltage), step-down (the output voltage is lower than the input voltage) and inverting (the output voltage has the opposite polarity to the input). As can be seen from the figure, they differ only in the way they connect the inductance; otherwise, the principle of operation remains unchanged, namely.

switching power supply voltage

Figure 5 - Typical block diagrams of switching power supplies

The key element (usually bipolar or MIS transistors are used), operating with a frequency of the order of 20-100 kHz, periodically applies the full input unstabilized voltage to the inductor for a short time (no more than 50% of the time). Pulse current, flowing through the coil, ensures the accumulation of energy reserves in its magnetic field of 1/2LI^2 at each pulse. The energy stored in this way from the coil is transferred to the load (either directly, using a rectifying diode, or through the secondary winding with subsequent rectification), the output smoothing filter capacitor ensures a constant output voltage and current. Output voltage stabilization is ensured automatic adjustment the width or frequency of pulses on the key element (a feedback circuit is designed to monitor the output voltage).

This, although quite complex, scheme can significantly increase the efficiency of the entire device. The fact is that, in this case, in addition to the load itself, there are no power elements in the circuit that dissipate significant power. Key transistors operate in saturated switch mode (i.e., the voltage drop across them is small) and dissipate power only in fairly short time intervals (pulse time). In addition, by increasing the conversion frequency, it is possible to significantly increase power and improve weight and size characteristics.

An important technological advantage of pulse power supplies is the ability to build on their basis small-sized network power supplies with galvanic isolation from the network to power a wide variety of equipment. Such IP are built without the use of bulky low-frequency power transformer according to the high-frequency converter circuit. This is, in fact, typical diagram pulsed power supply with voltage reduction, where the rectified mains voltage is used as the input voltage, and a high-frequency transformer (small-sized and with high efficiency) is used as the storage element, from the secondary winding of which the output stabilized voltage is removed (this transformer also provides galvanic isolation from the network ).

The disadvantages of pulsed power supplies include: the presence of a high level of pulsed noise at the output, high complexity and low reliability (especially in handicraft production), the need to use expensive high-voltage high-frequency components, which in the event of the slightest malfunction easily fail “en masse” (with In this case, as a rule, impressive pyrotechnic effects can be observed). Those who like to delve into the insides of devices with a screwdriver and a soldering iron will have to be extremely careful when designing network pulse power supplies, since many elements of such circuits are under high voltage.

4. Varieties of circuit solutions for switching power supplies

The SMPS diagram of the 90s is shown in Fig. 6. The power supply contains a network rectifier VD1-VD4, a noise suppression filter L1C1-SZ, a converter based on a switching transistor VT1 and a pulse transformer T1, an output rectifier VD8 with a filter C9C10L2 and a stabilization unit made on the stabilizer DA1 and optocoupler U1.

Figure 6 - Switching power supply from the 1990s

The SMPS diagram is shown in Fig. 7. Fuse FU1 protects elements from emergency situations. Thermistor RK1 limits the charging current pulse of capacitor C2 to a value safe for the diode bridge VD1, and together with capacitor C1 forms an RC filter, which serves to reduce impulse noise penetrating from the SMPS into the network. Diode bridge VD1 rectifies the mains voltage, capacitor C2 is a smoothing one. Voltage surges in the primary winding of transformer T1 are reduced by the damping circuit R1C5VD2. Capacitor C4 is a power filter from which the internal elements of the DA1 chip are powered.

The output rectifier is assembled on a Schottky diode VD3, the output voltage ripple is smoothed out by the LC filter C6C7L1C8. Elements R2, R3, VD4 and U1, together with the DA1 microcircuit, provide stabilization of the output voltage when the load current and mains voltage change. The power-on indication circuit is made using LED HL1 and current-limiting resistor R4.

Figure 7 - Switching power supply from the 2000s

Figure 8 shows a push-pull switching power supply with a half-bridge connection of the power final stage, consisting of two powerful MOSFET IRFP460. The K1156EU2R microcircuit was chosen as a PWM controller.

Additionally, using a relay and limiting resistor R1 at the input, soft start, allowing you to avoid sudden surges of current. The relay can be used for voltages of both 12 and 24 volts with the selection of resistor R19. Varistor RU1 protects the input circuit from pulses of excessive amplitude. Capacitors C1-C4 and two-winding inductor L1 form a network noise suppression filter that prevents the penetration of high-frequency ripples created by the converter into the supply network.

Trimmer resistor R16 and capacitor C12 determine the conversion frequency.

To reduce the self-induction emf of transformer T2, damper diodes VD7 and VD8 are connected in parallel to the transistor channels. Schottky diodes VD2 and VD3 protect switching transistors and microcircuit outputs reverse voltage DA2 from impulses.

Figure 8 - Modern switching power supply

Conclusion

In the course of my research work, I conducted a study of switching power supplies, which allowed me to analyze the existing circuitry of these devices and draw appropriate conclusions.

Switching power supplies have much greater advantages compared to others - they have higher efficiency, they have significantly less weight and volume, in addition, they have a much lower cost, which ultimately leads to their relatively low price for consumers and, accordingly, high demand in the market.

Many modern electronic components used in modern electronic devices and systems require high quality nutrition. In addition, the output voltage (current) must be stable, have the required shape (for example, for inverters), as well as a minimum level of ripple (for example, for rectifiers).

Thus, switching power supplies are an integral part of any electronic devices and systems powered by both industrial network 220 V, and other energy sources. At the same time, operational reliability electronic device directly depends on the quality of the power source.

Thus, the development of new and improved switching power supply circuits will improve the technical and operational characteristics of electronic devices and systems.

List of used literature

1. Gurevich V.I. Reliability of microprocessor relay protection devices: myths and reality. - Energy Problems, 2008, No. 5-6, pp. 47-62.

2. Power supply [Electronic resource] // Wikipedia. - Access mode: http://ru. wikipedia.org/wiki/Power_source

3. Secondary power source [Electronic resource] // Wikipedia. - Access mode: http://ru. wikipedia.org/wiki/Secondary_power_source

4. High-voltage power supplies [Electronic resource] // Optosystems LLC - Access mode: http://www.optosystems.ru/power _supplies_about. php

5. Efimov I.P. Power sources - Ulyanovsk State Technical University, 2001, pp. 3-13.

6. Areas of application of power supplies [Electronic resource] - Access mode: http://www.power2000.ru/apply_obl.html

7. Computer blocks power [Electronic resource] - Access mode: http://offline.computerra.ru/2002/472/22266/

8. Evolution of switching power supplies [Electronic resource] - Access mode: http://www.power-e.ru/2008_4_26. php

9. Operating principle of switching power supplies [Electronic resource] - Access mode: http://radioginn. ucoz.ru/publ/1-1-0-1

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