In order to continuously supply energy for consumers such as computer, telecommunication, control equipment, precision instruments, laboratory and hospital which are sensitive to disturbances in the network and power outages and due to the extreme necessity of these consumers Electronic equipment called UPS is used. In addition to uninterrupted energy supply, UPS should prevent the penetration of noise and network distortion to the consumer's sensitive equipment by stabilizing and regulating the network power. In the servers of ISP centers, in addition to data transfer and data network management, data storage is also done constantly. Therefore, if the power supply to these centers is interrupted even for a moment, there is a possibility of losing part of the information or creating inconsistency, as well as the collapse of the information exchange network, which can cause great financial losses to that group.In general, in terms of design structure, UPS are placed in one of three modes: online, offline, and line-interactive. Regardless of the specific design of each one, some important features are common to all UPS. All of them have batteries and they store energy in the batteries as long as the city electricity is usable, and after the city electricity is cut off, they convert the battery energy into AC alternating current. Therefore, all systems must have a battery charging circuit and an inverter. In order to feed the load directly from the city electricity, the UPS also has a bypass system. In many cases, the output switch circuit is completed by using static switches. In normal conditions, the energy of the batteries is supplied by the power grid [5] in order to establish a connection between the power grid and the batteries, a charger is needed.In addition to various control and measurement devices, chargers have several general devices such as step-down transformers, rectifier diodes, and filters, which perform the power conversion process. Today, most chargers work on the basis of the thyristor. Thyristors are active when they receive a command from the gate. The thyristor passes the voltage by taking the command from the control board. In fact, the thyristor is an automatic switch that passes the current according to the required ratio. The thyristors that are controlled by pulse receive the pulses from a regulator that is used in the board to adjust and time delay the firing point of the thyristor.Based on the comparison between the output voltage signal and the reference voltage, the regulator determines the delay of applying the pulses, and thus the output voltage is adjusted. In the chargers, various protection devices are installed, including the RFI relay to eliminate Radio frequencies and preventing their interference and return on the network, as well as the cooling system that is mostly used in high-power chargers and the phase control relays that are used for three-phase ups in order to match the phase sequence. These relays cut off the power when the voltage rises and depending on the type of relay setting, if there is a problem with the phase sequence, there will be no interruption in the charging current, but the relay will send an alarm. The DC voltage relay may also be installed in the charger, which controls the direct voltage and sends an alarm if the voltage is too low or too high.The ground relay is also used in chargers and its job is to check the voltage with the ground and if the balance is not established, it sends an alarm. In reference [13] various types of batteries and chargers have been introduced and in references [11, 17] a review of battery charging topologies to support AC and DC power systems has been given and since the control circuit of chargers also has It is important in reference [7], a control circuit topology for charging mode has been introduced, which includes the lifetime of the lithium-ion battery, and a comparator has been used for the charging mode controller, and reference [10] is a battery charge with an inverter. It has introduced low-cost and practical PWM using fuzzy logic control method for UPS. In reference [16], a DC to DC converter is used to charge the battery and a structure is given to reduce the current ripple in this converter. Also, the battery current and voltage control is done using a PI controller.In order to reduce the current and voltage harmonics, the method of isolating the input current from the output with the help of interface transformers [8] or the use of active filters can also be suitable solutions [9] to adjust the load voltage, we can replace DC line interactive UPS with AC UPS. Let us popularize three phases [4] In reference [6], the topology for the data center is presented using a scalable module, which seeks to improve efficiency and reduce costs. AC-DC converter and DC-DC converter are formed, the first part converts AC input voltage to DC voltage and the second part converts DC voltage to several DC voltage outputs at different levels such as 3.3v, 5v, 12v, -12v convertsContinuous UPSs, if the loads under their power supply are AC powered, it is necessary to place an intermediary between the batteries and the load called an inverter (DC to AC converter), which requires its own control circuits in reference [14]. Four topologies have been presented for UPS inverter control, a control method based on repetition to compensate harmonics and provide an almost sinusoidal and balanced voltage has been proposed in reference [3], also a control model has been proposed in reference [2] that The purpose of the design is to produce sinusoidal output voltage with low harmonics using LC output filter.In this article, the structure of common UPS that is used to power loads that have a rectifier at their input, such as powering computers, servers, and all loads that are fed with the help of an inverter, has presented a new plan. In this plan, the inverter in common UPS is removed Therefore, the cost of the provided UPS system is much lower than the existing ones for ac electrical machines [18], [19], [20], [21].
Section 2 describes the types of regular UPS structures, Section 3 presents a new structure for UPS used to feed servers, which has a much lower cost than conventional UPS, Section 4 includes the results of simulation and The tests performed to check the accuracy of the method are presented and the final conclusions from the performed work are stated in section 5.
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