Improving the energy efficiency of backup energy supply sources in base stations of mobile networks

. In the work in the MATLAB program, an IGBT-transistor inverter was modelled to improve the energy efficiency of a mobile uninterruptible power supply. In order to improve the efficiency of the uninterruptible power supply, its principal and structural diagrams have been developed.


Introduction
In power supplies that consume direct current sources, for example, batteries, solar cells, etc., transistor converters are considered the main functional node that converts one nominal DC voltage into a different nominal DC voltage and its polarity.These switches are galvanically isolated from the primary supply bus.Transistor voltage converters are also a central functional node in transformer-less input power supplies.These voltage converters can also consume energy from the AC network.Single-cycle and two-cycle transistorized constant voltage converters are also used in power supplies [1][2][3][4].
In increasing the efficiency of any electronic device, the operating conditions, load and elements of this device are of great importance.To improve the efficiency of the mobile uninterruptible power supply source, taking into account its operation time, the sinusoidal nature of the output voltage, and the provision of high-quality energy supply to devices, the inverter was modelled in the MATLAB program, the necessary transistor was selected, and a high-quality voltage was obtained at the output The structural scheme of this voltage converter is made of four transistors.Two of them, VT1 and VT2, are connected to the primary winding of the TV transformer with its collector.The second block of transistors is designated as a power amplifier, which is connected with its collector circuit to the collector windings of cascade transistors that change the primary voltage, the collector circuit of this power amplifier block is connected to the distribution generator circuit [5][6].
Two types of two-step voltage transformers are used in power supplies: storable and nonstorable power transformers.
In manufacturing electronics, the problem of power conversion arises in many cases for various types of electrical equipment.In addition, these situations are not excluded even in ordinary home conditions.
We call the devices that convert current direct current into alternating current an inverter.But in this thesis, I will have to look at DC voltage converters.These devices are also widely used in radio electronics.
In non-saturating power transformers, transistors are switched off and on due to the saturation torque of the core.In this transformer, the reverse link TB (base winding) circuit is located in the common magnetic conductor of the supply transformer.The switching frequency is determined by the parameters of the transformer and the voltage in its primary winding (collector).The main disadvantage of such converters is the sudden increase in current through the open transistor at the moment of transformer saturation, which leads to additional power losses in the transistor.
In our republic and all over the world, as a result of the decrease in reserves of energy resources (coal, oil, fuel oil, etc.), their prices increase, and the rapid development of technology, it is necessary to find non-traditional and renewable sources of energy resources and use them.Great importance is attached to mastering.
The conversion of solar energy to electricity and the development of devices based on non-conventional and renewable energy types is considered an actual direction for the Central Asian region [8].
There are many cases of sudden power outages in the service sector, especially in rural areas.In such conditions, backup power supply devices using a 12 V car battery and 100-300 W solar modules as the primary power source can be of great help [9].
In this section, the analysis of the device that ensures the automatic connection of the load to the mains or voltage transformer is reviewed.

Experimental technique
The tested circuit of the reserve power source converts the direct voltage (12-15 V) to a variable voltage of 240 V 50 Hz and provides an output power of 800 W, automatic charging device, protection of the battery from full discharge, the battery in the battery it has overvoltage protection, switching to reserve supply when the voltage in the network disappears, and automatic switching to the network when the voltage appears in the network.During daylight, the battery can be charged both from the solar module and from the grid [10].
The block diagram of the reserve supply source is shown in Figure 1.Electromagnetic relays K1 and K2 provide automatic connection of the device to contact groups K 1.1, K 1.2, and K2.1.Points 1 and 2 mark the connection nodes of the automatic circuit breaker.The disconnect serves to disconnect the converter from the mains voltage and the battery.In this case, the reverse-connected diode VD1 protects the battery from discharge, and as a result, the solar module can be left connected to the battery during the night.The autonomous energy system set for the power supply of the device with a voltage of 220 V and a power of 800 W is shown in Table 1.In such a systematic energy device, the operation of the maximum loaded energy device at night is 1-1.5 hours.The device must always be connected to the mains voltage.AB is automatically disconnected from the charging circuit of a fully saturated battery, and when the voltage decreases, it is connected to the charging device again.If there is no voltage in the network for a long time, it is partially charged from the AB solar battery during daylight hours.

Modelling stage
Converters that convert direct current into alternating current and operate on an autonomous load are called inverters.Depending on the number of voltage phases at their outputs, they are divided into single, three, and multi-phase inverters.Depending on the construction of the circuits, they are divided into zero-removed, bridge-type and semi-bridge-type [5][6].Modelling of IGBT transistor inverters.Model universal bridge and frequency (1080 Hz) and modulation index (0.8) selected PWM pulse generator is found externally from discrete blocks.Harmonic analysis is performed using the Powergui/FFT tool (Figure 3).The word inverter refers to devices that convert direct current into alternating current.The essence of the inverter is that the primary windings of the power transformer (and in some cases, the subject can also go directly to the load) are connected in series in a direct current network with the opposite direction.At this time, a right angle, trapezoidal, step or sinusoidal alternating voltage appears in the windings of the transformer.[4] The device that performs such changes is called an inverter.Thus, in the secondary power supply sources, the inverter includes disconnecting and connecting elements that convert direct current into right-angle alternating voltage; provides the control scheme of disconnecting and connecting power elements, and their serial connection; a power transformer that transforms alternating voltage and provides electrical isolation of output circuits from each other.
In radio electronic devices, transformers are widely used as power disconnecting and connecting elements in the secondary power supply source.It is convenient from the point of view of energy to operate transistors in cut-off mode, at this time the voltage in the primary winding of the transformer changes like a jump.In this case, the power losses in the transformers will be smaller, and the useful work coefficient will be higher.

Fig. 4. Input and output oscillograms of inverter signals
The installed parameters of the load and the source are presented in Figure 3.The input and output oscillograms of the inverter signals obtained as a result of modelling are presented in Figure 4. Now, to perform the electrical calculation, first of all, it is necessary to work with the initial data, these are the voltage of the supply source (in our case, the car battery): U0=12 V; transformer output voltage UKE=25 V; the maximum current of the secondary winding I2=2 A; the generation frequency of the converter is f=10 kHz [5][6][7][8].After modelling, spectral analysis can be performed in the range from 0 to 5000 Hz. (Figure 5).Tests have shown that if the AB is correctly connected to the device, the mains voltage is not allowed to be connected to the inverter output, and the load is connected with a suitable power, the backup power supply has a continuous working life and does not require additional maintenance.can't.
According to the principle of operation, transistor inverters are divided into self-excited converters and independent-excited converters.Self-excited converters are made in the form of auto generators with a reverse connection with a transformer.Self-drive inverters, in addition to proprietary inverters, which in this case can be called power amplifiers, also include low-power control generators that provide pulses for driving power transistors.
The connection pole of the power diode of the rectifier to the secondary winding of the transformer determines the method of transmission of the energy to the load.When the VT transistor is open in a voltage converter with a reversed diode, the supply voltage U is connected to the primary winding of the transformer, and a voltage pulse of duration tU is transformed in the secondary winding.But at this time, the VD1 diode connected in the opposite direction will be closed and Rup will be disconnected from the load changer.When the transistor is closing, at the pause moment tp, the polarity of the voltage in all windings of the transformer changes to the opposite sign, the diode VD1 is opened, and Rup is connected to the rectified voltage load.In the next cycle, the transistor VT is opened, the diode VD1 is closed, and the capacitor Sf is discharged to the load Rup.With this, the capacitor Iup provides a constant current flow.At this time, the inductance of the secondary winding of the transformer acts as a choke of the rectifying filter.
The simplest supply sources are rectifiers and transformers, which change the rectified and alternating voltages at the output as the input changes.
Controlled and uncontrolled rectifiers, whose secondary power sources are diodes, thermistors and transistors, are widely used.
Voltage and current stabilizers.Electricity receiving voltage from secondary sources of electricity varies between 20-30%.In addition, during operation, the current required by the equipment changes.Therefore, parametric and compensatory stabilizers are used in most secondary power sources.
In auto generators with saturated powerful transformers, transistors are connected by changing the polarity of the voltage in the transformer windings when the core is saturated.In such converters, the feedback is due to the total magnetic resistance of the TA circuit of the transformer.Frequency converters are determined by the parameters of the transformer and the voltages in the primary windings.The disadvantage of such converters is that the current flowing in the open transistor increases during saturation, which causes additional power losses in the transistors [5].
The scheme of the reserve supply source changes the constant voltage (12-15) V to an alternating voltage of 240V, 50 Hz and provides an output power of 4000 W, an automatic charger, protection of the battery from full discharge, the voltage on the battery it has automatic over-voltage protection, switching to the reserve supply when the voltage in the network disappears, and switching to the network when the voltage appears in the network.During bright sunny days, the battery can use both the solar module and the electricity from the grid.
In auto generators with non-saturated powerful transformers, transistors are connected through a feedback circuit until the TA transformer is saturated.Low-power connection transformers are used as such connections.Due to their simplicity and high reliability, twostroke converters with saturated and unsaturated transformers are used for supply sources with a power of several tens of watts.
The rapid development of computing techniques, advances in programming technologies, and the latest advances in mathematical modelling methods: simulation modelling, the creation of emulation and simulation models of electronic components, and the introduction of virtual modelling systems into the design practice, led to the creation of automated jobs for the designer of electronic devices based on computerization.brought Today, the computer has become the main technical tool for the design of modern measuring devices with high accuracy.
The transmitting and receiving antenna of the mobile communication network works with an average of 3 kW of electricity.In this graduation thesis, to prevent the causes of interruptions during communication and many other problems in the network due to the failure of the mobile communication antenna due to a sudden power outage, it is necessary to obtain electricity from additional solar energy and use it through the necessary devices.it is about ensuring automatic connection to the mobile communication antenna and ensuring that the connection is not interrupted.
First of all, we determine the power consumers of mobile communication antennas, the following picture shows the mobile communication container device, here the power consumers are described.
Air conditioner 2 x 1000V= 2000 W, Lighting Lamps 2 x 20V= 40 V Fire alarm 2 x 30V= 60V Amplifier 1x 300 V= 300 V Transmitting antenna power amplifier 4x 150V= 600V Total: 3000W Based on this calculation, it can be said that the output power of the continuous supply source being designed is very suitable.Batteries can work for 1-2 hours when switching to reserve power consumption at average power consumption.At the same time, the time to fully recharge the batteries is 8 hours.After the calculation below, we use devices that receive electricity from additional solar energy (solar panel, charge controller, accumulator, inverter) with an average of 4000 V.
The device must always be connected to the mains voltage.AB is automatically disconnected from the charging circuit of a fully saturated battery, and when the voltage decreases, it is connected to the charging device again.If there is no voltage in the network for a long time, it is partially charged from the AB solar battery during daylight hours.

Conclusion
The test results showed the following: 1.When there is no voltage in the network and 90 A/s, AB is used as the primary energy source, the reserve supply source of 300-350 W keeps the device in working condition for 2.5-3 hours.
2. On an outdoor day, a 100 W solar battery restores (40÷50%) the energy used by AB for 6-7 hours.
3. In field conditions, when there is no voltage network, it is desirable that the power of the solar cell is increased by 2-3 times, and the AB power is increased to 300 A/s.
From this tested mobile uninterruptible power supply, with the appropriate selection of AB capacity, solar battery and inverter power, telecommunications communication, radio stations, medical systems, household radio electronic equipment and also control systems of complex technical objects can be supplied with quality power.

Fig. 1 .
Fig. 1.Block diagram of the reserve supply source

Table 1 .
A set of autonomous energy systems for the energy supply of the device.