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Today, the editor will show you how to test the UPS power supply in the data center computer room. The knowledge points in the article are introduced in great detail. Friends who feel helpful can browse the content of the article with the editor, hoping to help more friends who want to solve this problem to find the answer to the problem. Let's follow the editor to learn more about "how to test the UPS power supply in the data center computer room".

Foreword:

In order to ensure the stability and reliability of computer work, data security and accuracy, more and more UPS power supply is used in the computer room, and some even call UPS power supply the protector of the computer, and the safe operation of UPS power supply has also become a top priority. This paper shares the classification and application of UPS power technology and the AC/DC conversion technology, integrated voltage regulator and power conversion circuit that must be detected by UPS power supply.

(1) Classification and application of UPS power supply technology

(1) usually store the energy in a certain form, and then turn it into a power supply load when in use, the typical equipment is a variety of storage batteries that are common to people.

(2) to convert other energy into electricity, such as hydraulic, firepower, wind power and nuclear power generation, which is generally referred to as the primary power supply (commonly known as power grid or municipal electricity).

(3) in the process of power transmission, the power is converted or stabilized between the primary power supply and the load, which is generally called the secondary power supply (that is, to control the existing power supply).

What is described here is mainly the secondary power supply, that is, the input power supply (supplied by the power grid, etc.) is transformed into voltage, current, frequency, waveform and electric power supply load that meets the requirements in terms of stability and reliability (including electromagnetic compatibility, insulation, heat dissipation, uninterrupted power supply, intelligent monitoring). This is the most widely used field of power technology at present, which mainly studies how to use electronic technology to convert and control electric power. It widely uses the theories of electromagnetic technology, electronic technology, computer technology and material technology, and has a strong comprehensiveness. In engineering, the technology in this field is generally called "power technology".

In order to be different from other methods, the power supply equipment composed of electronic technology is usually called "electronic power supply". The working frequency of electronic power supply is from low frequency (several hertz) to high frequency (megahertz), and the output voltage is from several volts to tens of kilovolts. The output current is from microampere to ten thousand ampere. With the development of science and technology, the demand for power technology is higher and higher, the specification is more and more, and the technology is more and more difficult. The academic fields involved are also getting wider and wider. As far as the technology itself is concerned, it can be divided into three categories:

(1) DC power supply: the input power supply can be AC or DC, single-phase AC or three-phase AC, and the output is DC (including stabilized voltage or steady current), including linear control and switching control.

(2) AC power supply: the input power supply is mostly single-phase or three-phase AC, and the output is still AC (single-phase or three-phase, which is called inverter when the output is DC), including voltage stabilization, current stabilization, frequency stabilization, uninterrupted power supply and so on.

(3) Special power supply (or industrial power supply): for example, electroplating, electrolysis, electric welding, laser, high voltage and other types of power supply, the input is mostly AC power, and the output is in the form of DC, AC or pulse.

The basic content of power technology: in general, the main content of power technology includes the following parts: power electronic devices, power conversion circuit, power supply machine and system, power electronic devices:

(1) uncontrolled devices: mainly all kinds of power diodes, including rectifier tube, rectifier bridge module, fast recovery diode, power Schottky diode and so on.

(2) semi-controlled devices: mainly thyristors (also known as thyristors). The control terminal of ordinary thyristors loses its control function after the device is turned on (so called semi-controlled devices). In order to turn off this kind of devices, we must rely on external conditions.

(3) full-control device: the control terminal not only has the ability to turn on the control device, but also has the ability to control its turn-off. For example, high power transistor (GTR), power field effect transistor (M05FET), gate turn-off (GTO) thyristor, M05 control thyristor (M σ), new insulated gate bipolar transistor (IGBT), static induction transistor (5 π) and so on.

(2) AC/DC transform technology

The conversion of alternating current to direct current is called AC/DC conversion, and the power flow of this conversion is transmitted from the power supply to the load circuit, which is generally called rectifier. For the occasion where the DC output voltage is required to be changed, the phase-controlled rectifier scheme or other control schemes can be adopted. There are many kinds of rectifier circuits with their own characteristics, and their basic circuits can be roughly divided into:

(1) according to the number of rectifying phases:

① single-phase circuit: single-pulse or double-pulse

② three-phase circuit: 3 pulse, 6 pulse or 12 pulse

③ polyphase circuit: P pulse.

(2) according to the characteristics of circuit control:

① uncontrolled rectifier circuit

② semi-controlled rectifier circuit

③ full-control rectifier circuit.

DC/AC,DC/DC,AC/AC conversion technology, this section briefly describes DC (DC) I AC (AC), DC (DC) I DC (DC), AC (AC) I AC (AC) three conversion technologies.

DC/AC transform technology

The conversion of direct current into alternating current is called DC/AC transform, which is commonly known as "inverter". In some special occasions, such as satellites, aircraft, ships, submarines, etc., there is no power frequency AC power supply (50 or ω Hz), only batteries or solar cells can be used, these are DC power supplies, when it is needed to supply power to AC loads, DC/AC conversion is needed. In addition, power frequency alternating current is not suitable for some loads, for example, 4 ∞ Hz alternating current is used in aircraft or related ground equipment, medium frequency or high frequency alternating current is needed for induction heating, and frequency conversion and variable voltage alternating current of induction motor is needed in a certain range. In the case of power frequency AC power supply, the power frequency AC power is first changed into DC, and then the inverter is transformed into AC of the required frequency and voltage. All these applications require DC/AC conversion technology.

With the development of power semiconductor devices, the scope of application of inverter technology has been further broadened, and it has penetrated into almost every field of national economy. In particular, the successful development of field control devices with high voltage, high current and high frequency functions has laid a foundation for simplifying the inverter circuit, improving the performance of the inverter and the wide application of high frequency pulse width modulation (PWM) technology.

Classification of DC/AC converters:

DC/AC converter (hereinafter referred to as inverter) can be divided into two categories: single-phase and three-phase. Single-phase inverter is suitable for medium and low power, and three-phase inverter is suitable for medium and high power. These two categories can be classified according to the following characteristics:

(1) according to the nature of the input DC power supply, it is divided into voltage source inverter circuit (input power supply is constant voltage source) and current source inverter circuit (input shock is constant current source).

(2) according to the characteristics of the circuit structure: half-bridge circuit; full-bridge circuit; push-pull circuit; other forms.

(3) according to the components of the circuit, it is divided into ordinary thyristor inverter circuit, high power transistor (GTR) inverter circuit, gate turn-off (GTO) thyristor inverter circuit, MOSFET (MOS field effect transistor) inverter circuit, IGBT inverter circuit and so on.

(4) according to the output waveform, it is divided into sine wave inverter circuit and non-sine wave inverter circuit.

(3) Integrated voltage regulator

Integrated voltage regulator is to use semiconductor technology and thin film process to make diodes, transistors, resistors, capacitors and other components in voltage stabilizing circuits on the same semiconductor or insulated substrate to form solid circuits with voltage stabilizing functions. integrated voltage regulators have developed rapidly in the past decade, and now there are hundreds of varieties at home and abroad. According to the working mode of the circuit, there are linear integrated voltage regulator and switch integrated voltage regulator. According to the structure of the circuit, there are monolithic integrated voltage regulator and combined integrated voltage regulator. According to the connection mode of the pin, there are three-terminal integrated voltage regulator and multi-terminal integrated voltage regulator. According to the manufacturing process, there are semiconductor integrated voltage regulator, thin film hybrid integrated voltage regulator and thick film hybrid integrated voltage regulator.

Integrated voltage regulator is a voltage stabilizing circuit made on semiconductor silicon wafer by epitaxy, oxidation, lithography, diffusion and metal evaporation. The various components of the integrated voltage regulator are made in the same process with high reliability, and it is also helpful to improve the voltage stabilization accuracy, reduce the volume and reduce the weight.

The common integrated voltage regulators are as follows:

(1) Multi-terminal adjustable integrated voltage regulator. The sampling resistance of this kind of voltage regulator and the components of the protection circuit need to be connected externally, and it has more external terminals, so it is easy to adapt to different uses. Its output voltage is adjustable to meet the requirements of different output voltages.

(2) three-terminal fixed integrated voltage regulator. This kind of voltage regulator has three terminals: input, output and common terminal, and the output voltage is fixed (generally divided into several levels). This kind of products have the advantages of easy to use, stable performance and low price, so they have been widely used and have basically replaced the voltage stabilizing circuit composed of discrete devices.

(3) three-terminal adjustable integrated voltage regulator. It has three terminals: input, output and adjustment. The output voltage can be continuously adjusted by connecting two resistors at the regulating end. This kind of integrated voltage regulator can be selected when high voltage stabilization accuracy is required and the output voltage needs to be arbitrarily adjusted within a certain range. It can also be divided into positive and negative output voltage and output current, so attention should be paid to the electrical parameter characteristics of each series of integrated voltage regulators.

1. The principle of chip circuit

The circuit principle of the integrated voltage regulator is basically the same as that of the discrete transistor voltage regulator, and it is also composed of adjusting elements, error amplifier, reference voltage, comparison, sampling and other main parts, but the integrated voltage regulator makes full use of the advantages of integrated technology. many analog integrated circuit methods are used in line structure and manufacturing process. Compared with the discrete component regulator, such as bias circuit, current source circuit, basic voltage source circuit, various forms of error amplifier and the unique starting circuit and protection circuit of the integrated voltage regulator, the integrated voltage regulator has the advantages of small size, low cost, easy to use, high performance index and so on.

2. High frequency switching power supply

At present, high-frequency switching power supply is mostly used in space technology, computer, communication and household appliances. The efficiency, volume and weight of the switching power supply are better than those of the linear stabilized power supply. The adjusting tube of the switching power supply works in the switching state, the loss is low, and the efficiency can reach 75-95; the stabilized power supply is small in size and light in weight; the power consumption of the adjusting tube is low, and the volume of the corresponding radiator is also small. In addition, the switching frequency works at tens of kHz, the filter inductance and capacitance can be used with smaller components, and the allowable ambient temperature can also be greatly increased. However, due to the complexity of the control circuit of the adjusting device and the high output ripple voltage, the application of switching power supply is also limited.

The key to the miniaturization of electronic equipment is the miniaturization of the power supply, so it is necessary to reduce the loss in the power circuit as much as possible. When the adjusting tube in the switching power supply works in the switching state, there must be switching loss, and the loss increases proportionally with the switching frequency. On the other hand, the loss of magnetic components and capacitive components such as transformers and reactors in switching power supply increases with the increase of frequency.

At present, the bipolar transistor is used in the switching power supply in the market, the switching frequency can reach 1 ∞, and the switching frequency using MOSFET can reach 5 ∞ kHz. In order to increase the switching frequency, the switching loss must be reduced, and high-speed switching devices are needed. Resonant circuits can be used for switching frequencies above megahertz, which is called resonant switching mode. This method can greatly improve the switching speed, in principle, the switching loss is zero and the noise is very small, which is an effective way to improve the working frequency of the switching power supply. Several megahertz converters with resonant switching mode have been put into practice.

The integration and miniaturization of switching power supply is becoming a reality. at present, an integrated module in which the power switch and the control circuit are integrated on the same chip is being developed. However, the problems of electrical isolation and thermal insulation must be solved if the power switches and control circuits, including feedback circuits, are integrated on the same chip. at present, countries all over the world are making great efforts to develop a new type of switching power supply. it is constantly developing in the direction of high frequency, circuit simplification and control circuit integration.

3. Source-side power factor correction technology

The power factor (A) correction technology on the source side (also known as the input side) is proposed for the power electronic equipment with nonlinear load composed of rectifier and capacitor filter. the main purpose is to reduce the harm of high-order harmonics generated by electrical equipment to the power grid. The high-order harmonics in this kind of load current not only increase the loss on the transmission line, waste a lot of electric energy, but also affect the normal operation of other nearby electrical equipment. For this reason, some international standards related to this have been formulated, such as IEC552-2. These standards make specific restrictions on the input power factor and waveform distortion of electrical devices.

Power factor correction is abbreviated as PFC. There are two main methods to improve the source power factor: one is meta-source power factor correction technology, the other is active power factor correction technology. The former is mainly aimed at the low power factor problem caused by many inductive loads of motors in power supply systems and larger factories and mining enterprises. The method of correction is to connect the appropriate capacitors at the population of the power grid to make the λ value as close as possible to 1, in order to achieve the purpose of energy saving, that is, what we often call reactive power compensation. The latter is mainly aimed at the load of switching power supply. due to the rapid development of computer and program-controlled telephone exchange in recent years, switching power supply and uninterruptible power supply (UPS) are widely used, and most of the input side of these power devices are nonlinear working mode of direct rectifier and capacitor filter, so PFC technology has been widely valued and widely used.

The correction method of power factor: the basic idea of active power factor correction is to rectify the input AC voltage with full wave, convert the rectified voltage from DC to DC, and make the input current follow the voltage waveform after full wave rectification automatically through proper control, so that the input current is sinusoidal. Although PFC is also a switching power supply, it is obviously different from the traditional switching power supply.

(4) Power conversion circuit of power supply technology

In the process of transformation, in addition to making the power device work in the linear state, it often works in the switching state, according to the set time sequence, under the action of the control signal to realize the transformation of electric energy. The working process of the device will be accompanied by the transfer of current between the branches, so it is sometimes referred to as "commutation". For the circuit composed of semi-controlled devices, because the device itself has no turn-off ability, it is often turned off with the help of external conditions in the process of commutation. Successful commutation is a necessary condition for the normal operation of semi-controlled circuits, so the commutation process is the main content of this kind of circuit analysis, and the commutation technology is the core of this kind of conversion technology.

1. Power conversion circuit

From the point of view of power conversion function, there are four categories:

(1) change alternating current into direct current, that is, AC/DC transform. The conversion circuit to achieve this function is generally called rectifier circuit or rectifier.

(2) change direct current into alternating current, that is, DC/AC transform. The conversion circuit to achieve this function is generally called inverter circuit or inverter.

(3) change one kind of direct current into another kind of direct current, namely DC/DC transform. Through this conversion, the amplitude or polarity of DC voltage (current) can be changed, which is generally called DC / DC converter or DC/DC converter.

(4) change one kind of alternating current into another kind of alternating current, namely AC/AC transform. Through this transformation, the conversion of AC voltage (current) and frequency is realized, the former is called AC voltage regulating circuit (such as voltage regulator, current regulator), and the latter is called frequency conversion circuit (or frequency converter). Sometimes it is necessary to change the number of phases (for example, single-phase to three-phase or three-phase to single-phase, etc.).

The above four conversion circuits are collectively referred to as "converter technology" in terms of their technology, and their circuits can be used either singly or in combination. For example, a commonly used transformation form, the power frequency city electricity (single-phase or three-phase) is directly rectified into direct current, and it is turned into high-frequency alternating current through the inverter circuit (positive and negative rectangular pulse with adjustable pulse width or quasi-sinusoidal pulse with adjustable pulse frequency). And then through rectification into DC power supply load. In the high frequency conversion link, the output DC voltage is stabilized by pulse width modulation. This is the circuit mode of the commonly used high-frequency switching power supply, which adopts the combined conversion mode (there are two rectifiers and one inverter).

2. Control mode

In the process of transformation, in addition to making the power device work in the linear state, it often works in the switching state, according to the set time sequence, under the action of the control signal to realize the transformation of electric energy. The working process of the device will be accompanied by the transfer of current between the branches, so it is sometimes referred to as "commutation". For the circuit composed of semi-controlled devices, because the device itself has no turn-off ability, it is often turned off with the help of external conditions in the process of commutation. Successful commutation is a necessary condition for the normal operation of semi-controlled circuits, so the commutation process is the main content of this kind of circuit analysis, and the commutation technology is the core of this kind of conversion technology.

In the process of Ac/OC conversion, high-frequency conversion is often introduced to reduce the volume of power equipment, reduce weight, improve efficiency, improve dynamic characteristics and other purposes, the conversion frequency is generally tens of kHz to hundreds of kHz. In the 1970s, the DC linear power supply supplied by 50Hz AC power supply was developed to the DC switching power supply with switching frequency b, which is known as "but kHz revolution". However, after only more than 10 years, the switching frequency of the switching power supply has reached above.

The control modes of various conversion circuits can be summarized into the following three types:

(1) Phase (phase) control (control) mode: the change of the amplitude of the control signal is converted into the phase change of the pulse triggered by the converter device, which is often used in the rectifier power supply or AC voltage stabilized power supply.

(2) Frequency (rate) control (control) mode: the change of the amplitude of the control signal is converted into the change of the pulse frequency triggered by the converter device, which is often used in the inverter power supply.

(3) chopping (wave) control (control) mode: refers to the change of the amplitude of the control signal into the change of the "turn-on time ratio" of the converter device, which is often used in the DC converter circuit.

The above three control methods can also be combined, for example, when chopping and frequency control are used at the same time, form sinusoidal pulse width modulation (Sinewave-PWM referred to as SPWM), which is often used in AC converter.

3. Composition of power supply system

The composition of the general power system is provided by municipal electricity (power grid) or storage battery or solar or fuel generator; rectifying equipment converts the AC generated by municipal electricity or generator into direct current, or converts the direct current of the storage battery into direct current of other voltages to the DC distribution panel; the alternating current from the municipal electricity or generator is sent to the AC distribution panel through voltage stabilizing equipment In order to improve the reliability of power supply, there is an uninterruptible power supply (ups) in the power supply system. When the power supply is interrupted, its energy is supplied by storage battery or oil generator, and its output is sent to the AC distribution screen. For safe power supply, it is equipped with lightning protection device, which protects rectifier equipment, AC voltage stabilizing equipment, ups and generator. Rectifier equipment, ups and solar energy can all charge the battery in the picture.

This system diagram well illustrates the relationship between all kinds of equipment. of course, in order to further improve the reliability of power supply, standby equipment, intelligent monitoring, display and alarm can also be set up. Power technology plays an obvious role in promoting science and technology and industrial and agricultural production, and countries all over the world attach great importance to the development of this technology. The power supply technology of our country keeps up with the international advanced level and has made great progress in the past 20 years. The overall development trend is:

(1) Power semiconductor devices: focus on the development of fully controlled power devices. At present, power MOSFET and 1GBT devices are developing rapidly. Because this device has the ability of self-turn-off, it can eliminate the commutation circuit used in the original semi-controlled devices, so it has the advantages of simplifying the circuit, improving reliability, increasing efficiency, reducing cost and increasing the switching frequency. To further reduce the volume and weight, improve the output waveform, reduce noise and other good results, power semiconductor devices continue to increase capacity, improve dynamic performance, to modular, combined direction.

(2) Power conversion circuit: the fully controlled device and pulse width modulation (PWM) are widely used at present, and the source-side power factor correction (PFC) circuit is adopted to make the input current sinusoidal, so as to save electric energy, reduce the interference to the power grid, and overcome the disadvantage of low input power factor of phase control mode.

At present, new circuits such as resonant soft switching have been widely used to develop the working frequency of the switching power supply from 100kHz to megahertz, further improve the efficiency, miniaturize the power supply equipment and significantly reduce the ripple voltage, thus improving the performance of the power supply. from the point of view of control means, the hardware circuit composed of original discrete components and small and medium-sized integrated circuits has been developed into a software control mode composed of microprocessors and single-chip microprocessors. In order to achieve a higher degree of digitization and intelligence, and further improve the reliability of power equipment, it can be seen from the above that power technology is developing rapidly, and it will make greater contributions to production and scientific and technological progress.

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