The principle of operation of switching power supplies. Diagram of a switching power supply

Power supplies have always been important elements of any electronic devices. These devices are used in amplifiers, as well as receivers. The main function of power supplies is considered to be the reduction of the limiting voltage that comes from the network. The first models appeared only after the AC coil was invented.

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

Device power supply

If we consider the conventional power supply, which is used in radios, it consists of a frequency transformer, a transistor, and also several diodes. Additionally, there is a choke in the circuit. Condensers are installed in different capacities and can vary greatly in parameters. Rectifiers are usually used as a capacitor type. They belong to the category of high-voltage ones.

The work of modern units

Initially, the voltage is applied to the bridge rectifier. At this stage, the peak current limiter is activated. This is necessary so that the fuse does not burn in the power supply. Then the current passes through the circuit through special filters, where its transformation takes place. Several capacitors are required to charge the resistors. The node starts only after the breakdown of the dinistor. Then, the transistor is unlocked in the power supply. This makes it possible to significantly reduce auto-oscillations.

When a voltage is generated, the diodes in the circuit are activated. They are connected with each other by cathodes. The negative potential in the system makes it possible to lock the dynistor. Relief of starting the rectifier is made after locking the transistor. In addition, current limitation is provided. To prevent saturation of transistors, there are two fuses. They work in the chain only after a breakdown. To start feedback, you need a transformer. Feed it in the power supply of the impulse diodes. At the output, alternating current passes through the capacitors.

Features of laboratory blocks

The principle of operation of pulsed power supplies of this type is based on an active current conversion. Bridge rectifier in the standard scheme provided one. In order to remove all the interference, filters are used at the beginning, as well as at the end of the circuit. Condensers impulse laboratory power supply is conventional. Saturation of transistors occurs gradually, and this has a positive effect on diodes. Voltage regulation in many models is provided. The protection system is designed to save the blocks from short circuits. Cables for them are usually used by non-modular series. In this case, the power of the model can reach up to 500 watts.

The connectors of the power supply in the system are most commonly installed at the ATX 20. To cool the unit, a fan is mounted in the casing. The speed of rotation of the blades should be regulated in this case. The maximum load of a laboratory-type unit should be able to withstand at 23 A. At that, the resistance parameter is maintained at an average of 3 ohms. The limiting frequency that a pulsed laboratory power supply has is 5 Hz.

How to repair devices?

Most power supply units suffer from burned fuses. They are located next to the capacitors. Start the repair of switching power supplies with the removal of the protective cover. Further it is important to inspect the integrity of the chip. If defects are not visible on it, you can check it with a tester. To remove the fuses, it is necessary first to disconnect the capacitors. After that, they can be easily extracted.

To check the integrity of this device, inspect its base. Burned fuses in the lower part have a dark stain, which indicates damage to the module. To replace this element, you need to pay attention to its marking. Then in the electronics store you can buy a similar product. The fuse is installed only after the condensation has been fixed. Another common problem in power supplies is considered to be malfunctions with transformers. They represent boxes in which coils are mounted.

When the voltage to the device is very high, they can not stand. As a result, the integrity of the winding is disrupted. It is impossible to repair the impulse power units with such a breakdown. In this case, the transformer, like the fuse, can only be replaced.

AC Adapters

The principle of operation of switching power supplies of network type is based on low-frequency reduction of the amplitude of the interference. This is due to the use of high-voltage diodes. Thus, controlling the limiting frequency is more effective. In addition, it should be noted that the transistors are of medium power. The load on the fuses is minimal.

Resistors in the standard circuit are used quite rarely. In many respects this is due to the fact that the capacitor is able to participate in the current conversion. The main problem of the power supply of this type is the electromagnetic field. If capacitors are used with a small capacitance, then the transformer is in the risk zone. In this case, you should be very careful about the power of the device. Limiters for peak current, the network switching power supply has, 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. To start the rectifier, only transistors are used. The locking process, in turn, is necessary to activate the filters. Condensers can also be used as a separation type in the system. In this case, the start-up of the transformer will be much faster.

Application of microcircuits

Microchips in power supplies are used in a variety of ways. 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 in different capacities, and they are quite different in dimensions.

You can independently solder the microcircuits. In this case, you need to calculate the limiting 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 done with double lanes. Pulsations 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. You can adjust the pulse power supply in different ways. Voltage regulation is carried out taking into account the type of transformer. To cool the device use conventional coolers. The problem with these devices, as a rule, is the excess current. In order to solve it, protective filters are used.

The power of the devices fluctuates around 300 W on the average. Cables in the system are used only non-modular. Thus, short circuits can be avoided. The power supply connectors for connecting devices usually install the ATX 14 series. The standard model has two outputs. Rectifiers are used for increased voltages. Resistance they are able to withstand at 3 ohms. In turn, the maximum load impulse regulated power supply takes up to 12 A.

Operation of 12 volt units

The switching power supply (12 volts) includes two diodes. In this case, the filters are installed with a small capacity. In this case, the pulsation process is extremely slow. The average frequency fluctuates around 2 Hz. The efficiency of many models does not exceed 78%. These blocks also differ in their compactness. This is due to the fact that the transformers are installed at low power. In cooling, they do not need.

The circuit of the switching power supply 12V additionally implies the use of resistors with the marking P23. Resistance they are able to withstand only 2 Ohm, but for the device of this power it is enough. A switching power supply 12V is most often used for lamps.

How does the unit work for the TV?

The principle of operation of pulsed power supplies of this type is the use of film filters. These devices are able to cope with interference of varying amplitude. Winding the throttle they have a synthetic one. Thus, the protection of important sites is ensured by quality. All gaskets in the power supply are insulated from all sides.

The transformer, in turn, has a separate cooler for cooling. For ease of use, it is usually set to silent. The limiting temperature of these devices can withstand up to 60 degrees. The operating frequency of the switching power supply of TVs 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 the 24 volt models, rectifiers use low-frequency ones. With interference, only two diodes can successfully cope. The efficiency of such devices can reach up to 60%. Regulators for power supplies are installed quite rarely. The operating frequency of the models does not exceed 23 Hz on the average. Resistors can withstand only 2 ohms. Transistors in models are installed with the marking PR2.

To stabilize the voltage, resistors are not used in the circuit. Filters pulse power supply 24V has a capacitor type. In some cases it is possible to meet separating species. They are necessary to limit the limiting frequency of the current. To quickly start the rectifier, the transistors are rarely used. The negative potential of the device is removed using a cathode. At the output, the current is stabilized by locking the rectifier.

Power flanks on the DA1 circuit

Power supplies of this type from other devices differ in that they are able to withstand a large load. There is only one condenser in the standard circuit. The regulator is used for normal operation of the power supply unit. The controller is installed directly near the resistor. Diodes in the circuit can be found no more than three.

Directly the inverse transformation process begins in a dynistor. To start the unlocking mechanism, a special choke is provided in the system. Waves with a large amplitude are damped at the capacitor. It is usually installed as a separating type. Fuses in the standard circuit are rare. The reason is that the limiting temperature in the transformer does not exceed 50 degrees. Thus, the ballast throttle manages its tasks independently.

Models of devices with DA2 chips

The chips of this type of switching power supplies among other devices are distinguished by increased resistance. They are used mainly for measuring instruments. An example is an oscilloscope that shows oscillations. Stabilizing the voltage for it is very important. As a result, the instrument's performance will be more accurate.

Many models are not equipped with regulators. Filters are basically two-sided. At the output of the circuit, transistors are installed conventional. All this makes it possible to withstand the maximum load at the level of 30 A. In turn, the limit frequency indicator is at the level of 23 Hz.

Blocks with installed DA3 chips

This chip allows you to install not only a controller, but also a controller that monitors fluctuations in the network. Resistance transistors in the device are able to withstand approximately 3 ohms. A powerful switching power supply DA3 with a load of 4 A cope. You can connect the fans to cool the rectifiers. As a result, the device can be used at any temperature. Another advantage is the availability of three filters.

Two of them are installed at the inlet under the condensers. One separating type filter is available at the output and stabilizes the voltage that comes from the resistor. Diodes in the standard scheme can be found no more than two. However, much 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 not advisable to install them on measuring instruments.

How does the unit work on VD1 diodes?

These units are designed to support up to three devices. Regulators in them are three-sided. Cables for communication are installed only non-modular. Thus, the transformation of the current occurs quickly. Rectifiers in many models are installed series KKT2.

They differ in that they can transmit 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.