RU2426215C2 - Uninterrupted power supply source for ac loads - Google Patents

Uninterrupted power supply source for ac loads Download PDF

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RU2426215C2
RU2426215C2 RU2008147515/07A RU2008147515A RU2426215C2 RU 2426215 C2 RU2426215 C2 RU 2426215C2 RU 2008147515/07 A RU2008147515/07 A RU 2008147515/07A RU 2008147515 A RU2008147515 A RU 2008147515A RU 2426215 C2 RU2426215 C2 RU 2426215C2
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voltage
inverter
op
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Георгий Александрович Жемчугов (RU)
Георгий Александрович Жемчугов
Юрий Теодорович Портной (RU)
Юрий Теодорович Портной
Лев Яковлевич Раскин (RU)
Лев Яковлевич Раскин
Лев Николаевич Седов (RU)
Лев Николаевич Седов
Владимир Григорьевич Яцук (RU)
Владимир Григорьевич Яцук
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Федеральное космическое агентство Федеральное государственное унитарное предприятие НАУЧНО-ПРОИЗВОДСТВЕННОЕ ПРЕДПРИЯТИЕ ВСЕРОССИЙСКИЙ НАУЧНО-ИССЛЕДОВАТЕЛЬСКИЙ ИНСТИТУТ ЭЛЕКТРОМЕХАНИКИ С ЗАВОДОМ имени А.Г. ИОСИФЬЯНА НПП ВНИИЭМ
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Abstract

FIELD: electricity.
SUBSTANCE: uninterrupted power supply source (UPS) is arranged in the form of a reversible converter (RC) with an intermediate link of high frequency and ports for connection of a DC source and loads. Besides, the RC is made with two "input-output" ports of power circuits, one of which is made as a port of DC terminals, with an accumulator battery connected to it at the input, and arranged in the form of an input port for operation in inverter mode and an output port for operation in a rectifying mode of RC, and the other port of AC terminals is arranged as an output one in the inverter mode and an input one in the rectifying mode of RC operation, besides, for electric connection between AC and DC terminals of the specified ports there are two links connected as serially joined to each other, one of which is a high-frequency link, and the other one is a link of an industrial frequency autonomous inverter. At the same time both links are equipped with drivers to control power modules. Both links are used with the help of control facilities in inverter and rectifying modes. At the same time in the rectifying mode and during normal functioning of AC circuit the essential loads are connected directly to the main AC circuit via an automatic breaker. At the same time, using control facilities of RC, it ensures generation of a controlled reactive power into an AC circuit, to which a voltage sensor is additionally connected with a voltage controller.
EFFECT: minimised dimensions and weight of an uninterrupted power supply source.
10 cl, 10 dwg

Description

Previous technical solutions

The presented invention relates to the field of electrical engineering and more specifically to the field of uninterruptible power supply (UPS) alternating current, in which an uninterruptible power supply (UPS) upon failure of the main power source of the alternating current network (usually a generator) provides power to responsible AC consumers by conversion of direct current electricity stored in a drive (for example, in a storage battery - AB) into alternating current energy. During normal operation of the main AC mains, the UPS charges and then recharges the battery by rectifying the voltage supplied from the mains.

A UPS is known according to US patent No. 5563778 of 08/10/96, in which, during normal operation of the network, the supply of responsible consumers is made from the main network alternatively either through a series-connected rectifier and inverter, or through a bypass line (bypass).

In case of failure of the source of the main network, power supply of responsible consumers is made only from the battery through the inverter. In this UPS, the principle of “on-line” type can be applied when, in any condition of the main network, the supply of responsible consumers is carried out through the inverter 30 (Fig. 1), and in the case of even a sudden disconnection of the main network source, the transition to battery power occurs without power outage. This UPS (patent No. 5563778) also provides for the possibility of operating according to the "off-line" type, in which, under normal conditions of operation of the main network, the power supply for responsible consumers is made by the bypass line, and when the main source is disconnected, through the inverter 30 from the battery. To reduce the power interruption time of critical consumers in the interval of switching the power supply, thyristor switches are included in the circuit at the inverter output and in the bypass circuit. A block diagram of this UPS is shown in FIG. The UPS in FIG. 1 differs from its predecessors in that for galvanic isolation and the use of different voltage levels at the output, one 3-winding transformer 150 is included instead of two 2-winding transformers. The disadvantages of this UPS: increased power of the rectifier, designed to power the inverter and at the same time to charge the battery, and increased power loss in normal modes (in the rectifier and inverter), which is necessary for the implementation of the type of "on-line", as well as inclusion in the circuit additional thyristor switches to accelerate the process of transferring the load to the inverter and vice versa. In one of the modifications of this UPS, in addition, a transformer for 50 (60) Hz is used, which is much more bulky and expensive than the high frequency transformers used in the UPS proposed here.

A UPS is also known, protected by US patent No. 6479970 of 12/12/2002, in which a high-frequency unit containing a three-winding high-frequency transformer T5 is used (Fig. 2). A battery (AB) 56 is connected to one winding N3a and N3b of the transformer T5 through an adaptive reversing converter 40 and a high-pass filter 54. A main network is connected to the second winding through a rectifier 18 and an input inverter 26. A rectifier with a filter 36 is connected to the third winding working at the output, N2a and N2b, and a low-pass filter 46 is connected in series with it and then responsible consumers 48 are connected to it, requiring uninterruptible power supply . This UPS implements a principle of operation similar to the on-line type - during normal operation of the main network and in case of failure, the power supply for the responsible AC consumers is performed through a high-frequency link and a low-frequency inverter. The difference from the classical "on-line" system, where the isolation between the rectifier in the power supply circuit from the main network and the battery is carried out with direct current and the transition to power from the battery takes place without interruption, in this UPS the isolation between the battery and the main network is done with alternating current at transformer T5, and to switch from one mode to another, a short pause is required. The disadvantage of the UPS in FIG. 2, as in the UPS in FIG. 1, remains the need for increased rectifier power and increased losses in normal operation from the main network.

A system with a UPS is also known, which does not have some of the disadvantages of the first and second analogues, is protected by US patent No. 6160722 from 12/12/2000, closest in technical essence to the claimed invention and which is its prototype.

Figure 3 shows a diagram of a UPS prototype, in which there are 3 input-output ports of power circuits: a source port 10 of the main AC network (AC) 401, designed to connect to the main AC network; port of a direct current source (DC) 431, designed to connect AB 460 to it, and a load port 403, designed to connect responsible consumers of AC load 20 to it. During normal operation of the main network, energy is transmitted from source 10 through reactor L 1 and a rectifier 410 to tires 402a, 402b. Then, the rectified voltage is converted by an inverter 430 to a high-frequency voltage supplied to a double-winding high-frequency transformer T 1 , and then after rectification in a reversing converter, the energy is supplied to a charge (recharge) of AB 460. At the same time, responsible AC consumers 20 are supplied with power from DC bus 402a, 402b through inverter 420 with a second reactor L 2 connected in series, i.e. In the normal mode of operation of the main network, critical consumers are supplied with power through a rectifier 410, a high frequency inverter 430, a rectifier, and then an industrial frequency inverter 420, due to which losses increase: the installed capacity of the rectifier and UPS is increased. In emergency mode, when the operation of the main network is disrupted, the responsible consumers of alternating current 20 are supplied from AB 460 through a high-frequency inverter 436, a high-frequency transformer T 1 , a reversing converter operating in this case as a rectifier (on elements Q5, Q6, D1, D2 node 430), and through an inverter 420 with a series-connected reactor L 2 (in Fig. 3, all devices and connection circuits are presented for a single-phase circuit, which is probably due to the fact that this UPS is considered by the authors as a low-power device). For this reason and because, most likely, due to the low voltage on the AB, the authors of the invention protected by US patent No. 6160722 did not encounter the need to overcome some of the difficulties associated with introducing a high frequency link into the circuit, which inevitably arise when high power converters, which will be discussed below.

In addition to the 3 analogues discussed above, it was not possible to find closer analogues. As will be seen from the further description of the present invention, as a result of a search by sources of patent and scientific and technical information, a set of features characterizing the proposed uninterruptible power supply for AC consumers was not found, and thus, the present invention meets, in our opinion, the patentability condition - "novelty."

Based on a comparative analysis of the proposed technical solutions with the prior art according to the sources of scientific, technical and patent literature, it can be argued that there is an unevident cause-and-effect relationship between the totality of signs (including distinctive) and the functions performed by them, and the goals achieved. Based on the foregoing, we can conclude that the totality of the proposed technical solutions in the proposed device does not follow explicitly from the prior art and, therefore, meets the condition of patentability - "inventive step".

The proposed set of technical solutions can find application in uninterruptible power supplies, including autonomous electric power systems, and therefore, this set of technical solutions meets the patentability condition - “industrially applicable”.

Description

Proposed in this invention an improved powerful uninterruptible power supply (UPS) is shown (as one of the modifications) in figure 4. In contrast to the prototype, it has 2 ports of input-output power circuits: a DC port 10, to which a power storage unit, such as a battery (11), is connected externally, and an industrial frequency port 20, to which responsible AC consumers are connected 32 and through the circuit breaker 33, the rest of the AC network.

The UPS 40 consists of two main links: a high-frequency (RF) link 6, which provides the necessary galvanic isolation between ports 10 and 20 using transformer 5 (T1) included in this link 6 and a stand-alone power frequency inverter 7, which is based on the well-known 3-phase bridge circuit of an autonomous inverter 22 and an LC filter. These two links 6 and 7 are connected in series and form a reversible converter 40 (OP).

OP operates in two main steady state modes:

- in the power mode of AC consumers, when responsible consumers of AC 32 receive power from AB 11 through OP 40;

- during normal operation of the main AC network 30, when ordinary consumers of alternating current 34 and responsible consumers 32 receive power from a source (for example, a synchronous generator 35 (G1) of the main AC 30, and through the OP 40 the battery 11 is charged or recharged and DC 16 power supply (if any).

With some degree of conventionality, the first mode is called the inverter mode OP 40, and the second - the rectifying mode OP 40.

A certain conditionality is determined by the fact that, although the OP 40 as a whole works, for example, in the inverter mode, the node 21 of the high-frequency link 6 included in its structure operates in the rectifier mode. A similar situation arises in the rectifier mode OP 40, when the node 21 of the high-frequency link 6 included in its composition operates in an inverter mode.

The main technical objective of the proposed invention is to minimize the size and weight of the UPS. It was carried out by adopting a number of circuitry decisions that made it possible to collectively obtain a positive result.

These technical solutions are discussed below.

1) The UPS is made according to the principle of a reversible converter (OP), in which all nodes of the power unit operate in both main modes - rectifier and inverter, instead of using a separate set of nodes and elements in each of the two modes, while in normal operation the main network is AC current 30 power supply for responsible consumers of alternating current 32 is made directly from the main network 30, and not through the inverter, as this happens in the OP, performed on the principle of "on-line"; such nodes include a transformer 5, necessary for galvanic isolation of DC and AC networks, and standard transistor-diode modules 14 and 21, each connected to it from the primary (in the inverter mode of the OP) and secondary (in the same mode) windings, each of which it works either in the inverter mode of the module, when all the elements of the module 141 ... 148, 211 ... 218 are used, or in the rectifier mode of the module, when only the inverse diodes 145 ... 148, 215 ... 218 are used, and the transistors do not open; in the inverter OP 40 mode, the module 14 connected to the primary winding of the transformer 5 from the DC source 11 side operates in the inverter mode of the module, and the module 21 connected from the opposite side of the transformer 5 operates in the rectifier mode of the module; in the rectifier mode OP 40, the functions of the modules are reversed, namely: the first module 14 goes into the rectifier mode of the module, and the other module into inverter mode.

2) A link of a stand-alone inverter of industrial frequency 7, connected with its DC clamps 421, 422 to DC terminals 321, 322 of the high frequency link 6 and AC clamps 423, 424, 425 through a current sensor 29 and a circuit breaker 31 connected to the port clamps AC 20, made on the basis of one or several parallel-connected standard transistor-diode modules on MOSFET or IGBT transistors and a 3-phase LC low-pass filter 27 and 28, the inductance of which in the case of parallel connection of the modules is also is divided by the same number of 3-phase inductance groups connected in parallel with a series connection of one module and one 3-phase inductance group, for a more reliable uniform current division between parallel connected modules. This link, although called the link of an autonomous inverter, is reversible, just like the high-frequency link, works in both steady-state OP 40 modes - inverter and rectifier. In inverter OP 40 mode, link 7 operates in a stand-alone inverter mode, in OP 40 rectifier mode, the same link 7 performs the function of a rectifier on the same standard module 22, whose transistors and reverse diodes are connected according to the 3-phase bridge circuit, and its reverse diodes allow perform this function, and using transistors controlled by the sinusoidal PWM method, a counter-EMF curve is formed for 3 phases of the bridge, adjustable in amplitude and phase (with respect to the amplitude and phase of the voltage in the main AC network), and, changing the magnitude (amplitude) of this curve is controlled by the flow of reactive power, and by changing the phase shift between the smooth component (first harmonic) of this curve and the voltage of the network, it is possible to control the flow of the active component of power to or from the main AC network. To ensure this, with the help of a microprocessor controller, low-current synchronization circuits of unlocking pulses of all power transistors are switched from a single stand-alone frequency generator to synchronization from the mains voltage through a phase-locked loop 46 (UPCH) with an additional phase fitting unit 47 (UPF).

It is quite obvious that the standard 3-phase bridge module can be replaced with 3 modules of 1-phase half-bridge or separate modules of 3-phase inverter and 3-phase bridge of reverse diodes or 6 single-key modules, which, of course, is worse than 3-phase bridge. It is also possible to use this link OP for cases of a single-phase AC network using a single-phase bridge module.

3) In order to provide power to critical consumers 32 directly from it in the normal mode of operation of the main network 30, but with improved quality of electric power in the alternating current network in static and dynamic modes, it is proposed to introduce controlled generation of reactive power from the OP 40 into the alternating current network 30.

Regulated generation of reactive power to the main AC network from the OP 40 in the rectifying mode of operation is performed not only in statics, but also in dynamics, namely after the moment of occurrence of a malfunction in the operation of the main AC network. In this case, according to the signals from voltage sensors 38 (DN3) and frequency 44 (DF), which will respond to a malfunction, and / or from accident sensors in the electric power system (EPS), not included in the UPS and not shown in Fig. 4, the controller 8 generates a command to turn off the circuit breaker 33 (Q3), which separates the OP 40 with the responsible consumers connected to it from the rest of the AC network. The proper time to turn off a powerful AC circuit breaker is usually 1-2 periods of the mains frequency, i.e. less than 40 ms, after which OP 40 at the command of controller 8, the OP is automatically switched on to work in stand-alone inverter mode, supplying critical consumers. In most cases, such a short power supply interruption for responsible consumers is acceptable, however, this power interruption can be reduced (up to 0) in cases where the AC load includes asynchronous and / or synchronous motors connected directly to the AC mains by the stator. Then, by controlled generation of reactive power by a reversible converter 40, the voltage in the AC network 30 is maintained at a level close to the nominal value, for which the OP 40 is equipped with a voltage regulator 43 (PH3) and a voltage sensor 38 (DN3), which operate in a steady-state rectifier mode OP 40 and continue to operate in a transitional mode from the moment of a malfunction in the AC network to the moment the OP 40 is turned on in stand-alone inverter mode. In this way, a UPS made in the form of an OP, due to the regulated generation of reactive power in terms of the quality of power supply of responsible consumers, becomes almost equivalent to a UPS made on-line, while retaining advantages over it in terms of installed capacity of the rectifier, and therefore in weight and dimensions .

To limit the current flowing from the OP 40 to the main AC 30 when the voltage regulator is in the rectifier mode and in the event of a short circuit in the main AC 30, as well as in the power supply network in the OP 40 inverter mode, to the AC circuit, connected to the terminals of the AC port 20 OP 40, a current sensor 29 and an AC limiting controller 41 (PT) connected thereto are included; To perform the functions of a voltage regulator in the rectifying mode and a current limiting regulator, a microprocessor controller 8, which is part of the OP 40, with an analog-to-digital converter can be used.

4) To ensure long-term operation of the OP 40 in the rectifier mode, smooth (without inrush current) transfer to the main source and to regulate the flow of active power through UPS 40, it is equipped with a synchronization system based on the phase-locked loop 46 (UPCH) (Fig. 4) with an additional phase fitting unit 47 (UPF) and with the possibility of using hard pulse synchronization.

5) Introduced a high-frequency reversible link 6, made on the basis of standard nodes 14 and 21 of transistor-diode key elements with one or more transformers 5 (T1) (Fig. 4 shows a modification with one transformer), providing galvanic isolation between DC circuits and AC circuits. A high-frequency link is proposed, which can be performed in various modifications, differing in the number of transformers and in the scheme of their connection with standard transistor-diode modules depending on the UPS power, voltage levels in the circuit necessary for the UPS to operate on the DC and AC sides , from the range of voltage changes during the discharge of AB 11, from the parameters of the selected standard modules, the maximum allowable unit power of the high-frequency transformer.

At present, devices with a high-frequency link — secondary power supplies with a relatively small unit power — the maximum are units of kilowatts, are mass-produced in different countries and by different companies. The proposed UPS is designed for rated power of tens and hundreds of kilowatts, and, despite the high power, the switching frequency in the high-frequency link should be high enough - according to preliminary estimates of 40-100 kHz, to get the effect of introducing such a link. At such switching frequencies, the most suitable key elements are standard modules on transistors MOSFET and IGBT, controlled by drivers 19, 23, 24 (figure 4), and, possibly, on lockable thyristors IGCT. The MOSFET modules have the best dynamic performance, and then the IGBT modules go. Using these modules without parallel and in some cases without a serial connection, it is not possible to carry out a UPS of the required high power. It is known that IGBT transistors, and especially MOSFETs, can be connected in parallel and provide a uniform distribution of current between them without any additional means due to the influence of a positive temperature coefficient of resistance of the MOSFET in the conducting state or voltage of the IGBT anode-cathode in the conducting state, which allows the inclusion of transistors in parallel to build capacity. However, a uniform distribution of voltage between series-connected modules is much more problematic. In the proposed multivariate high-frequency link 6 by using standard modules and transformers with the series connection of two or more transistor-module cells at the output of this link, when the modules are connected at the input of the same link in parallel, uniform compulsory voltage division between the connected transformer-module cells is ensured . At the same time, the current is also forcibly evenly divided between parallel connected modules connected to another winding of the transformer.

In the proposed multivariate HF link included in the OD 40, the minimum possible number of modules or transistor cells connected in series is uniquely determined by the voltage level at the input of the link of the autonomous inverter of industrial frequency 7, to which the intermediate link of HF 6 is connected taking into account the voltage variation range on AB 11, and this voltage level, in turn, is uniquely determined by the voltage level at the terminals of the AC port 20 of the UPS 40. The minimum number of consecutive cells can be determined by riding ratio (inverter inverter mode):

Figure 00000001

where U out.nom.hh.ef. - rated effective voltage at the output of the UPS in inverter mode at idle, effective value;

U mod. - rated voltage of the module;

Figure 00000002
- voltage conversion factor for a 3-phase bridge circuit;

γ max = 0.9 - the maximum duty cycle of the PWM control;

Figure 00000003
- the rate of change of voltage on the battery;

To ΔU = 1,03 - coefficient taking into account the voltage drop in the bridge transistors and in the filter reactors at the output;

To Ustap = 2 - voltage safety factor for the module.

According to the calculation for N min. the next largest integer is accepted. Using the above expression, the minimum required number of series-connected transformer-module cells can be determined for various combinations of nominal parameters of AC and DC networks selected by transistor modules, which will be described in more detail below.

6) Another feature of the proposed RF 6 link is that the modules 21 connected to the second winding of the transformer are assigned to the second group of modules, although they have the same circuit as the modules 14 of the first group - 1-phase bridge, but have a dramatically different characteristic. If the module of the first group operates in a voltage inverter mode with a capacitor 13 (C 1) at the input and with a step-by-step regulation of the step-down voltage, then the module of the second group works in the mode of a current inverter with a series-connected reactor in the DC link of the module and with pulse-width regulation overvoltage type. Such a technical solution allows the use of the same transformer (without switching in power circuits) in the inverter and rectifier OP modes; without such a solution, it would be necessary to do a tap-off in the winding or an extra winding and switch in the power circuit, since in the rectifier mode OP 40, to charge the AB 11, when the module of the second group operates in inverter mode, a higher voltage in the DC network is required, than when discharging AB 11.

7) In the RF link, planar transformers are installed, for example, manufactured by Payton (see Power Electronics magazine No. 3, 2005). Planar transformers and reactors provide the smallest dimensions and mass. Another advantage of these elements is small values of dissipation reactance, small losses in transformers and reactors, and in addition, due to the printed windings, good repeatability of parameters from one to another sample is ensured, which is essential for powerful UPSs containing a large number of parallel and series connected elements.

The multivariance of the execution of the RF 6 link is due to the fact that this link, along with the fulfillment of its main task, is the galvanic isolation of DC and AC networks using RF 5 transformers, which have the smallest possible installed power and, accordingly, weight and dimensions, but it also allows in some cases to obtain additional the ability to use the elemental base and the ability to select the most rational parameters.

8) In a number of cases (for example, in systems with a battery with a wide range of voltage changes from discharged to charged state - 175-320V), it turns out to be advisable to connect a reversible pulse DC / DC converter to direct current (chopper), stabilizing the voltage at the DC terminals of the OP, i.e. at the input in inverter mode. In the rectifying mode of OP, the same converter should provide regulation of the output voltage in this mode in the range of the battery charge.

In this case, there are 2 possible embodiments of the DC / DC converter:

- stabilization of the voltage at its output in inverter mode at the lower level of the natural range of voltage change on the battery during discharge (for example, 175V);

- stabilization of the voltage at the output of the DC / DC converter at or slightly above the upper limit of the range of voltage changes when the battery is charged. This solution will optimize the choice of transistor modules. The low stable voltage at the input of the inverter of the high-frequency component included in the OP allows the use of modules with low-voltage transistors having higher speed and higher rated currents. In another embodiment, a higher stable voltage allows you to reduce the current through the transistors of the inverter and will reduce the number of parallel-connected modules at the input of the OP in inverter mode. In each case, one or another version of the DC / DC converter can be used.

For greater clarity, we consider in more detail 5 options for the execution of the link HF 6 OP 40, differing in the characteristic performance of the link HF 6 and shown in figure 4-8.

The simplest modification of the OD 40 is shown in Fig.4. It is suitable for cases where transistors with a nominal voltage of 1200V are available, and in a 3-phase AC network 30, which includes an OP 40, the nominal line voltage is 220V, or when there are transistors with a nominal voltage of 2200-2400V, and the nominal the line voltage in the AC network is 380 V. In such cases, modification can be used without connecting cells or modules in series. To ensure increased power, parallel connection of single-cell links of RF 6 will be required, since The maximum unit power of the transformer is limited.

The reversible converter 40 in the power part consists of a capacitor 13 (C1) connected to the terminals of the port of the DC power circuit 10 through a current sensor 15 (DT1), connected in parallel to the DC terminals of the transistor-diode standard module 14, in which transistors 141 ... 144 and reverse diodes 145 ... 148 are connected according to the well-known scheme of a single-phase bridge, and a DC voltage sensor 18 (DN1) is connected in parallel to the capacitor and to the DC terminals of this module, and the AC terminals of module 14 are connected to the terminals (1H ... 1K) of the transformer 5, which is primary in the inverter OP mode, hereinafter referred to as the first, the other winding (2H ... 2K) of the transformer 5 are called the second, and the module 14 connected to the first winding of the transformer 5 belongs to the first group of modules, module 21 connected the second winding of the transformer (2H ... 2K), refers to the second group of modules of the high-frequency link 6. The module 21 of the second group, like the module 14 of the first group, has 4 transistors 211 ... 214 and 4 reverse diodes 215 ... 218 connected in 1- phase bridge connected by clamps alternating current to the second winding of the transformer, and a direct current circuit connected to its DC terminals, into which a reactor 25 (L1) is connected in series, from which the positive and negative pole circuits are connected to two DC poles of the next OP link - an autonomous inverter of industrial frequency 7. A large capacitor 26 is connected in parallel to these DC terminals of module 22. The transistors and diodes of the standard module 22 are connected according to the scheme of a 3-phase bridge voltage inverter. A 3-phase LC low-pass filter connected to a 3-phase inductance group 27 and a 3-phase group of capacitors 28 connected in parallel to the OP 40 3-phase AC power circuit is connected to the AC terminals of module 22. This circuit passes through a series-connected current sensor 29 to the power terminals of the AC port 20 OP 40. The voltage sensor 37 (DN2) and the frequency sensor 44 (DC) are connected to these terminals of the AC power circuit to regulate the voltage at the output of the OP in inverter mode, and the DN3 sensor for voltage regulation voltage at the input of the OP in the rectifying mode. Another voltage sensor (DN4) monitors the voltage on the remote part of the EPS to allow synchronization with this voltage. Switching circuits going to the sensors DN2, DN3, DN4 produce a switch 45.

For the initial data mentioned above, we verify that we can restrict ourselves to one cell without connecting the modules of the second group in series.

Figure 00000004

Figure 00000005

Consider the principle of operation of the first modification of OP 40 (figure 4), starting with the normal operation of the main AC network. In this mode, the transistor control system of both power links of the OP 40 is synchronized in line frequency from the voltage supplied to the OP from the main AC network. The frequency in the high frequency link and the carrier frequency of the PWM link of the autonomous inverter are formed as multiple frequencies of the main AC network. The synchronization was performed using the well-known phase-locked loop, implemented using a standard microcircuit (PLL), in addition to which a phase fitting control loop (UPF) 47 was introduced, which ensures the regulation of the charge current of AB 11 by the feedback signal from the DC sensor 17 (DT2 ) on the steps of charging or recharging AB 11 with current stabilization or by a signal from a DC voltage sensor 18 (DN1) on the steps of charging or recharging AB 11 with stabilization of voltage supplied from OP 40 to AB 11. Transistor the module 22 is controlled by the method of a sinusoidal PWM so that under the action of a current regulator 41 (RT) and / or a charge voltage 48 (RE) of direct current, changing the phase shift of the reference sinusoidal signals of three phases relative to the synchronizing voltages, and as a result, the smooth phase changes accordingly component of the counter-EMF, and thereby regulate the current and / or charge voltage of the battery 11. At the same time regulate the voltage in the AC 30 using a voltage sensor 38 (DN3) and voltage regulator 43 (PH3), which Exposure to the change of reference amplitude sinusoids and thus the change of reactive component of the current (power), and hence the voltage in the AC network. With this method of regulating the voltage in the AC network, the possibility of current overload is not excluded, and therefore OP 40 is additionally equipped with a current limiting regulator or current cutoff 41 (RT). The functions of all the regulators and PWM controllers can be assigned to the microprocessor controller 8, which performs other functions of control, protection, diagnostics and is part of the OP 40.

In the high-power OP 40, a link of a self-contained inverter of industrial frequency can be performed when two or more standard modules are connected in parallel, and then the inductance 27 of the LC filter is divided by the same number of parallel 3-phase circuits, and each inductance circuit is connected in series to the module's alternating current circuits 22, for better dividing the current between parallel connected modules.

The link of the 3-phase inverter 7 operates in the rectifier mode and provides a rectified voltage to the DC terminals of the module 21 of the second group of the high-frequency link, which has a series inductance 25 (L1) at the input and operates in the current inverter mode with a wide-ranging step-up regulation, for which at the beginning of each half-cycle, both transistors of one or both racks of a 1-phase bridge are unlocked, and thereby a short circuit is formed; the current in this circuit, which includes the inductance 25 (L1), increases linearly, after which two transistors remain open, through which the energy stored in the inductance is transferred to the remainder of the half-cycle through the transformer and the module of the first group 14, operating in this case in the rectifier mode due to the inverse diodes 145 ... 148 with the locked transistors 141 ... 144. In the case of the parallel inclusion of two or more groups in the high-frequency link, for evenly dividing the current between parallel connected nodes, the current can be adjusted using transistor inverters of the second group, for which each group includes a current sensor 15.

During normal operation of the main AC network 30, a malfunction may occur in it, as a result of which the voltage and / or frequency in the network decreases. Based on the signals from the frequency and / or voltage sensors or from any fault sensor in the electric power system, the microprocessor controller 8 generates a command to turn off the circuit breaker 33 that separates the OP 40 and the responsible consumers 32 connected to it from the rest of the alternating current network 30. Until the divergence of the main contacts of the switch 33, the voltage regulator 43 seeks to maintain voltage on the AC terminals of port 20, affecting the increase in the amplitude of the reference sinusoid of the SHI generator M and increase reactive power generation. Simultaneously with the command to turn off the rectifier, the controller 8 generates a command to turn off transistors 211 ... 214 of module 21, i.e. to stop the rectifying mode of the OP 40. At the moment of opening the power circuit by the switch 31 on the signal from its block contacts, the controller 8 gives a command to turn on the OP 40 in inverter mode - it allows the passage of pulses to unlock transistors 141 ... 144 high-frequency links and unlock transistors 221 ... 226 module 22, which include in the mode of a 3-phase autonomous voltage inverter, the controller 8, in addition, generates a command to turn off the rectifier controllers and turn on the inverter voltage regulator the press 42, acting on the PWM controller of the module 14 of the high frequency link 6, which ensures the stability of the voltage at the output of the OP 40 in its inverter mode.

In the interval from the moment of detection of a malfunction in the main network to the moment of separation of the OP with the responsible consumers connected to it, the frequency in the network can gradually decrease due to the run-out of load motors to which active power is not supplied, OP 40 is not yet turned on in inverter mode, and only reactive power is supplied, which ensures the maintenance of the voltage in the network. The transistors are controlled at the beginning of the emergency mode from the master oscillator, synchronized from the mains voltage, and then, upon command from the microprocessor controller, the external synchronization circuit of the master oscillator OP 40 is disconnected, and it smoothly switches to its own frequency, increasing the frequency at the output of the OP 40 to the nominal frequency value in inverter mode.

The second modification of the RF link corresponds to the more common combination of voltage levels of direct and alternating current (U AB = 290-180 V, U network number = 380 V) (Fig. 4). For more definiteness of the example, the power of the OD 40 in the inverter mode, taking into account the permissible overload, is 100 kW with cosφ = 0.7, and the maximum charge current is 11,400 A. The application is considered as modules for inclusion in the first and second groups of the RF 6 link module on transistors MOSFET or IGBT with a rated voltage of 600 V, which allows you to choose the frequency in the RF link 50 kHz.

The minimum allowable number of modules that you want to enable sequentially with the received input data is

Figure 00000006

This means that at least 4 modules in the second group and, accordingly, in the first group, also 4 modules connected in parallel on the DC side should be connected in series. With the received input data in inverter mode, the OP current at the input of module 14 is approximately

Figure 00000007

This means that when using modules with nominal parameters of 600 V, 300 A, a modification of the RF link 6 with 4 transformer-modular cells connected in series at the output of the RF link and in parallel at the input of the RF link can be applied. Thanks to this scheme, the connection of the modules provides in the statics a forced uniform voltage division between 4 modules 21 of the second group and a forced uniform current division between 4 modules of the first group without using other means of dividing current or voltage.

The advantages of the second OP modification are that instead of high-voltage modules for 2400 V, you can use a module with a rated voltage of 600 V with significantly higher speed, which allows you to take a higher frequency in the link, thereby reducing the size and weight of transformers, reactors and capacitors. The second advantage is that the modules of the first and second groups connected on opposite sides of the transformer are modules of the same type with the same parameters, which is more convenient in production practice. And one more property of this modification of OP can also be useful in production - the transformation ratio of the transformer is close to 1 and can be taken equal to 1, which simplifies the implementation of the transformer with printed circuit windings. The unit power of the transformer is ~ 25 kVA, i.e. corresponds to the maximum permissible value of planar transformers. If you need higher power values OP 40, you can turn on transformers or 4 cells in Fig.5.

Otherwise, according to the principle of operation and operating modes, the modification of FIG. 5 does not differ from the modification of FIG. 4.

For installations of high power more appropriate may be the third modification of the OP (Fig.6). It is distinguished by the fact that it can use low-voltage modules with MOSFET transistors, for example, with a nominal voltage of 200 V, having lower values of resistance in the conducting state, higher rated current, higher speed and lower losses in statics and dynamics.

In this case, the minimum required number of series-connected modules of the second group will be

Figure 00000008

With a small margin, it can be accepted that in the HF link in the second group, 12 transformer-module cells must be connected in series, and then in the first group, to ensure uniform voltage division between the cells of the second group, it is necessary to include 12 modules of the first group in parallel. The OP will include 12 transformer-modular cells. When using the same modules in the first group as in the previous modification (Fig. 5) at 600 V, 300 A, an OP with a power of 300 kW can be performed in this modification, because at 100 kW there will be a lot of redundancy. The transformation ratio will then be 3: 1. A certain drawback of this modification for practice is the use of different types of transistor modules in one OP with rated voltages of 200 V and 600 V.

With an even greater unit power of the OP, a modification of the RF link can be used, in which parallel and serial connection of modules on each side of the transformer is combined (Fig. 7). In this modification, the same modules are used in the first and second groups of the RF components with a rated voltage of 200 V, for which 3 groups of 12 cells must be connected in series on the side of the transformer where the modules were connected in parallel, and 3 groups of modules connected in series are connected in parallel second group. According to this scheme, an OP with a power of up to 900 kW can be performed using low-voltage modules with a nominal voltage of 200 V. Transformers in this modification have the same unit power of ~ 25 kVA as in previous versions (Figs. 4, 5, 6), the coefficient their transformation is close to 1.

Another modification of the RF link can be useful for use in the OP 40 for the widespread combination of the rated voltage in the alternating current network 380 V and the rated voltage of the transistor module 1200 V, and with acceptable frequency properties. In this case, the series connection of only two modules in the second group of modules and, accordingly, the parallel connection of also two modules in the first group of modules is required (Fig. 8).

Thus, the high-frequency link proposed for inclusion in the OP has, therefore, the following distinctive features:

- the possibility of using low-voltage semiconductor devices in high-power UPSs with the provision in the statics of a uniform voltage division between series-connected modules without the use of additional tools;

- provides the ability to perform a transformer 5 with a transformation coefficient close to or equal to 1;

- transformers in the RF link are made with the total minimum possible typical (installed) power equal to only the active power transmitted through the transformer in one of the two long-term OP 40 modes (usually in the inverter mode, in which the value of the active power is greater than in the rectifier mode); typical (installed) power does not increase by the ratio of the maximum voltage on the AB 11 to the minimum voltage on it, which usually happens due to the latitudinal regulation of the voltage supplied to its primary winding in the inverter OP 40 mode and thereby saving the volt-second area under the curve half-wave voltage on the winding;

- each transformer has only 2 windings;

- the ability to vary the unit power of the transformer to select the most rational value while maintaining the same total power of the transformers.

The sequential inclusion of transformer-modular cells, considered here, which ensures uniform voltage division in statics, does not exclude the use of additional measures to eliminate surge surges in the dynamics (for example, using varistors).

Figure 9 shows a diagram of these two embodiments of the input (meaning input for the inverter mode of the OP) circuits of the OP. In option 1 (Fig. 9, a) in the inverter OP mode, the input DC-DC converter operates as a step-down chopper, for which, using a transistor 52 (Tp1), pulse-width voltage regulation is performed at the input of the inverter bridge 14 and on the capacitor 13. In this The mode also uses the reverse diode 56 (D2) of the other transistor-diode pair. In the rectifying mode of the OP, the same DC / DC converter acts as a step-up chopper, in which the transistor TP2 (55) forms a short-circuited circuit for part of the switching period (in the closed state) for shorting the reactor 54 (L), and to another part of the same period, the energy stored in the reactor is transmitted through the diode 53 (D1) to the capacitor 51 (C2) and then to AB 11 (see figure 4).

In option 2 (Fig. 9, b), the exact same reversible DC-DC converter is used, but characterized in that in the inverter OP mode it works as a step-up chopper, stabilizing a voltage higher than the input, at the input of the inverter bridge 14 and the capacitor 13, by means of latitudinal regulation with the help of transistor 55 (TP2) and diode 53 (D1), and in the rectifying mode, OP is used as a step-down chopper, in which transistor 52 (TP1) and reverse diode 56 (D2) are used to regulate the voltage or current of the battery . In both cases, it is convenient that 1 standard half-bridge module can be used to provide the reverse conversion mode.

Any of the presented options of the DC-DC converter can be used in any modification of the OD 40 (Fig. 4 ÷ 8).

Above, for the construction of the HF 6 OP 40 link, standard modules of inverter single-phase full bridges or 1-phase half-bridges containing IGBT or MOSFET with reverse diodes were used. However, in some cases, it is more appropriate to use modules with a different composition and connection diagram of elements, for example, modules without reverse diodes (a 1-phase bridge module on MOSFET transistors from Microsemi type APT160HM45T1G) in combination with separate diode modules that may have higher rated currents, stress and better dynamic properties.

Information sources

1) US patent No. 5563778 from 08/10/1996

2) US patent No. 6479970 B2 of 12/12/2002

3) US patent No. 6160722 from 12.12.2000

4) Magazine "Power Electronics" No. 3, 2005

Claims (10)

1. An uninterruptible power supply for alternating current consumers for inverter or rectifier operation, made in the form of a reversible converter (OP) with an intermediate link of high frequency and ports for connecting a direct current source and consumers, characterized in that the OP is made with two input ports -exit ”of power circuits, one of which is made in the form of a port for DC clamps with a battery connected to it at the input and made in the form of an input port for operation in inverter mode e and an output port for operation in the rectifier mode of the OP, and the other port of the terminals for alternating current is made output in the inverter and input in the rectifier modes of operation of the OP, moreover, for electrical communication between the clamps of the direct and alternating current of these ports, two links are connected via circuit breakers interconnected in series, one of which is a high frequency link, and the other is a link of an autonomous industrial frequency inverter, both links are equipped with drivers for controlling power modules, both links being used by means of controls in the inverter and rectifier modes, while in the rectifier mode and with the normal functioning of the AC network, the responsible consumers are connected directly to the main AC network through a circuit breaker, while at the expense of control means the OP provides generation of regulated reactive power in an alternating current network, to which an additional voltage sensor with voltage regulator is additionally included.
2. The uninterruptible power supply according to claim 1, characterized in that in order to ensure reliable operation of the regulation system, the alternating current circuit connected to the terminals of the alternating current port has an additional current sensor, to which a current limiting regulator is connected, and voltage functions of voltage regulators and current limitations, as well as control, protection and diagnostics functions can be assigned to the microprocessor microcontroller included in the OP, and to switch the circuits coming from the voltage sensors to you during alternating current OP and in other parts of the alternating current network, a voltage switch is introduced.
3. The uninterruptible power supply according to claim 1, characterized in that the high-frequency link contains an input capacitor, an output reactor and an isolation transformer, while the stand-alone power frequency inverter contains an input capacitor and an LC low-pass filter at the output.
4. The uninterruptible power supply according to claim 3, characterized in that it is additionally equipped with a frequency adjustment unit (UPCH) configured for phase-locked loop frequency adjustment, as well as a phase adjustment unit for controlling the amount of transmitted active power from the main network to the battery.
5. The uninterruptible power supply according to claim 1, characterized in that the high frequency link of the reversible converter is made in the form of one or more transformer-modular cells, each of which contains at least one double-winding transformer with a primary winding connected to a standard module a single-phase inverter in the form of a module of the first group, while a module of a single-phase inverter in the form of a module of the second group is connected to the second winding.
6. The uninterruptible power supply according to claim 5, characterized in that the high-frequency link of the reversible converter is made in the form of several transformer-module cells, each of which contains at least one double-winding transformer with a primary winding connected to a standard module of the first group in this case, a module of the second group is connected to the second winding, the modules of the first group being connected in parallel to the terminals of the DC modules, and the modules of the second group of the same cells are connected to the terminals of constant t they are connected in series, and in the case of using lower-voltage (compared to the voltage of the power supply) modules of the first group they are connected in series with the DC terminals, and the modules of the second group of the same cells are connected in parallel with the DC terminals.
7. The uninterruptible power supply according to claim 5, characterized in that either the modules of 1-phase half-bridges or modules of single keys or modules of 1-phase zero circuits or separate modules of 1-phase bridges of transistors and single-phase bridges are used as modules of the first and second groups diodes, and in each group of modules two or more modules are included in parallel to divide the current according to the characteristics of these modules.
8. The uninterruptible power supply according to claim 5, characterized in that the inverters on the modules of the first group are made in the form of voltage inverters with latitudinal regulation of the output voltage of the step-down type and a parallel capacitor at the input, and the inverters in each cell on the modules of the second group are made in the form current inverters with latitudinal regulation of the output voltage of the increasing type with a series-connected magnetic reactor at the input.
9. The uninterruptible power supply according to claim 3, characterized in that planar transformers and reactors are used as transformers and reactors, the windings of which are made according to the printed wiring method.
10. The uninterruptible power supply according to claim 1, characterized in that between the DC clamps of the high-frequency link facing the DC energy storage device and the DC clamps of the reversible converter, a pulse reversible DC converter is included.
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RU2513547C1 (en) * 2012-09-07 2014-04-20 Общество с ограниченной ответственностью "Гамем" (ООО Гамем") Static reversible converter for power supply of alternating and direct-current consumers
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RU184526U1 (en) * 2018-01-29 2018-10-30 Федеральное государственное унитарное предприятие "Государственный научно-исследовательский институт авиационных систем" (ФГУП "ГосНИИАС") Offline power supply
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RU2513547C1 (en) * 2012-09-07 2014-04-20 Общество с ограниченной ответственностью "Гамем" (ООО Гамем") Static reversible converter for power supply of alternating and direct-current consumers
RU2533204C1 (en) * 2014-02-14 2014-11-20 Закрытое акционерное общество "Научно-производственный комплекс "ВИП" Modular uninterrupted direct-current power supply system for consumers
RU172332U1 (en) * 2017-01-09 2017-07-04 Федеральное государственное бюджетное учреждение "Петербургский институт ядерной физики" им. Б.П. Константинова AC GENERATOR IN Inductance Coil
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RU191898U1 (en) * 2018-02-20 2019-08-27 Общество с ограниченной ответственностью "АЕДОН" Modular secondary power supply

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