RU2377709C1 - Device for connecting independent voltage inverter to direct current voltage source (versions) - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention refers to electric engineering. Device (1) for connecting independent voltage inverter (2) to direct current voltage source (3) includes the main elements: reactor (4), inlet capacitor (5) of inverter, control unit (6) of charge of inlet capacitor of inverter, circuit (16) for limiting excess voltages in the form of damping circuit containing first (17) and second (18) resistors and damping capacitor (19). Switch (20) is connected in parallel to first resistor (17) into circuit (16). Circuit (16) can be used of one or several unipolar voltage limiters.

EFFECT: decreasing the following parametres and values of charging process of inlet capacitor by several times: inductivity of reactor and its weight; deviations of maximum values of charging current from average; deviations of maximum voltage values on outlet capacitor and other elements of independent inverter from direct current voltage source; energy losses in reactor and line connecting input terminals of independent voltage inverter to DC voltage source.

3 cl, 3 dwg

Description

A device for connecting an autonomous voltage inverter to a DC voltage source relates to electrical engineering, in particular, to devices for converting alternating current to direct and, conversely, direct current into alternating current using semiconductor devices: transistors and diodes in a bridge circuit.

A device for connecting an autonomous voltage inverter to a DC voltage source (first analogue). A schematic diagram of this device for connecting a single-phase voltage inverter is given in [1, pp. 404-404, Figure 24.1, c], and for connecting a three-phase inverter - in [1, pp. 416-418, Figure 24.10].

A known device for connecting a stand-alone voltage inverter to a DC voltage source contains an inverter input capacitor, the first terminal of which is connected to the first terminal of the said device, and the second terminal of the voltage inverter input capacitor is connected to the second terminal of this device. The first of these terminals is connected to the first output terminal of the specified DC voltage source and connected to the first input terminal of the above-mentioned stand-alone voltage inverter having the same polarity. If, for example, the first input terminal of the inverter is negative (the anodes of the valve arms diodes are connected to it), then the first output terminal of the source also has a negative polarity. And vice versa, when the first input terminal of the inverter is positive (the cathodes of the valve arms diodes are connected to it), the first output terminal of the source also has a positive polarity. The second terminal of said device is connected to a second output terminal of said DC voltage source, which has an opposite polarity to the first input terminal of the independent voltage inverter, and is connected to the second input terminal of said independent voltage inverter. The circuit connecting the analog input terminals to the output terminals of the DC voltage source includes a line of connecting wires or busbars (or a two-wire cable) and, optionally, an apparatus for current protection of the inverter and its load (for example, a circuit breaker).

The disadvantage of this device is that the amplitude and thermal pulse (integral of the square of the current over the entire passage) of the charging current of the inverter input capacitor after connecting the inverter with an uncharged capacitor to a constant current source with a nominal (or close to it) voltage are excessively large values. As a result, with a large capacity of the inverter input capacitor, the conductors of the line connecting the input of the voltage inverter to the DC voltage source, as well as the protection devices of this line and the inverter, can be damaged.

The magnitude of the amplitude value of such a current can be estimated based on the results of an analysis of the transient process of connecting the above-mentioned autonomous inverter with a nominal input voltage of 800 V and a nominal input current of 100 A. The inverter is connected to a direct current source with a voltage of 800 V using a two-wire cable with a cross section of 35 mm ² length 5 m. The active resistance of such a cable is 5.26 mOhm, and its inductance is 0.0013 mH. Let a controlled voltage rectifier be used as a source - a typical case in modern electrical engineering. At the output of such a rectifier, a large capacitor is included. Moreover, such a source acquires the properties of an ideal DC voltage source. The maximum value of the current passing through the specified cable and the input capacitor of the inverter takes place 0.7 ms after connecting to the source and is 130 kA. This amplitude value is 1300 times higher than the nominal value of the input current of the inverter. The heat pulse is 36.5 (kA) ² s. Such thermal impulse can withstand cables with rubber, or insulation similar to it in heat resistance, if the cross section of their current-carrying conductors is more than 44 mm ² . Therefore, for the considered example, a cable with a cross-section of 35 mm ² will fail from overheating by the starting current of the capacitor. The amplitude value of 130 kA will not stand the circuit breaker, with which the cable is connected to the source and the source is protected from short circuits in the inverter or in its load. Such switches allow current with an amplitude value of not more than 75 kA. If a cable with a length of 10 m, that is, two times longer, is used to connect the voltage inverter to an operating voltage, with a rated voltage, direct current source, then the thermal pulse will be reduced by half. Such an impulse can withstand cables, the cross-section of current-carrying conductors of which exceeds 31 mm ² . Consequently, a cable with a cross-section of 35 mm ² and a length of 10 m will remain intact. The maximum value of the starting current of the capacitor with such cable parameters is 69 kA, that is, it is only 8% less than the current limit for the circuit breaker. If the cable is laid in the same bundle with other cables, its cooling conditions are worsened, and to avoid overheating of the cable with a rated current of 100 A, it will be necessary to use a cable with large cross sections of current-carrying conductors. The transition to a cross section of 50 mm ² will lead to a decrease in the cable resistance. As a result, the maximum value of the starting current of the capacitor with such cable parameters becomes equal to 93 kA. The circuit breaker will fail.

Thus, at high values of the capacitance of the input capacitor and short power lines of the autonomous voltage inverter, the known device can be used to connect this inverter to a DC source in the absence of voltage at the output terminals of the source. Excitation of this source should be done gradually and only with the inverter input capacitor already connected.

, где L - индуктивность коммутирующего реактора, R - эквивалентное активное сопротивление цепи первичной обмотки. В него входят активные сопротивления коммутирующего реактора и входного сопротивления трансформатора. (Последняя составляющая находится путем гармонической линеаризации.) Волновое сопротивление последовательного резонансного контура,

, где С - емкость коммутирующего конденсатора, много больше половины R. Поэтому снижение второй амплитуды тока, проходящего по цепи первичной обмотки трансформатора, по отношению к первой амплитуде этого тока, относительно небольшое. Коммутирующий конденсатор зарядится до напряжения источника вскоре после достижения током, проходящим по цепи первичной обмотки трансформатора, первого амплитудного значения. Кроме того, при указанном соотношении между ρ и R, к моменту окончания первой половины цикла коммутирующий конденсатор зарядится до напряжения, которое почти в два раза превосходит напряжение источника, а к моменту окончания всего цикла он разрядится до напряжения, которое намного меньше напряжения источника. И так повторяется на каждом цикле. Накопительный конденсатор заряжается постепенно, в течение многих циклов. По мере его заряда растет эквивалентное активное сопротивление R, поэтому форма тока цепи первичной обмотки трансформатора несколько изменяется: амплитуды синусоиды уменьшаются, а ее период увеличивается.Also known is a charging converter for capacitive storage, which can be used as part of a device for connecting an autonomous voltage inverter to a DC voltage source. This charging converter (second analogue) is a DC converter with a series connection of the load to the resonant circuit. Its schematic diagram is given in [2, p. 84, figure 2.31], as well as in [3, p. 295, fig. 13.7, a]. The use of the second analogue allows us to get rid of the indicated drawback of the first analogue: the maximum value of the current consumed from the source when charging the storage capacitor connected to the output of the second analogue can be limited by the required value. The indicated maximum value of the input current of the second analogue is determined by the parameters of both the series resonant circuit, consisting of a switching reactor and a switching capacitor, and an isolation transformer. The primary winding of this transformer is connected in series with the indicated series resonant circuit, and the secondary through a rectifier is connected to the storage capacitor. The primary winding circuit is connected to the output of a bridge inverter, composed of four electronic keys (thyristors or transistors), shunted by reverse diodes. The inverter input is shunted by the input capacitor and connected to a DC voltage source. In this case, the cathodes of the two reverse diodes are connected to the positive pole of the source, and the anodes of the other two reverse diodes to the negative. The device in question operates cyclically. Each cycle begins by simultaneously closing one pair of electronic keys, which in this case connect the transformer primary winding circuit to the source. By this time, another key pair is already open. The current of the circuit of the primary winding of the transformer (and the secondary too) is a section of a sinusoid with a length of one period. In the first half of the cycle, the current flows through the electronic keys in one direction, and in the second half of the cycle, through the reverse diodes shunting these keys in the opposite direction. The amplitude of the sine wave decreases exponentially with a time constant that is equal to

where L is the inductance of the switching reactor, R is the equivalent active resistance of the primary circuit. It includes the active resistance of the switching reactor and the input resistance of the transformer. (The last component is found by harmonic linearization.) The wave impedance of the series resonant circuit,

, where C is the capacitance of the switching capacitor, much more than half R. Therefore, the decrease in the second amplitude of the current passing through the primary circuit of the transformer relative to the first amplitude of this current is relatively small. The switching capacitor is charged to the voltage of the source shortly after the current passing through the primary winding of the transformer reaches its first amplitude value. In addition, with the indicated ratio between ρ and R, by the time the first half of the cycle ends, the switching capacitor will be charged to a voltage that is almost twice the source voltage, and by the time the entire cycle ends, it will discharge to a voltage that is much less than the source voltage. And so it is repeated on every cycle. The storage capacitor is charged gradually over many cycles. As its charge increases, the equivalent active resistance R grows, so the current shape of the primary circuit of the transformer changes slightly: the amplitudes of the sine wave decrease, and its period increases.

The first drawback of this charging converter is obvious: it is an increased complexity (the presence of a transformer, a rectifier, a resonant circuit and an inverter). Its second drawback is that, to use it as a device for connecting an autonomous voltage inverter to a DC voltage source, the charging converter must be further complicated. It must be supplemented with elements that, after reaching the equality of the voltages of the storage capacitor and the source, disconnect this capacitor from the output of the charging converter and connect it to the input of the autonomous inverter.

There is also known a device for connecting an autonomous voltage inverter to a DC voltage source, the closest in technical essence to the claimed device and selected as a prototype. A schematic diagram of a device for connecting a single-phase voltage inverter is given in [4, p. 84, figure 2.31].

A known device for connecting a stand-alone voltage inverter to a DC voltage source comprises a reactor and an inverter input capacitor, the first clamp of which is connected to the first input and output terminals of the said device, while the first output terminal of this device is connected to the first input terminal of the stand-alone voltage inverter, and the first the input terminal of this device is connected to the first output terminal of the DC voltage source, and the first input terminal of the specified inverter and the first output terminal of said source have the same polarity, the second terminal of the inverter input capacitor is connected to the second output terminal of this device, which is connected to the second input terminal of the specified inverter, and to the first reactor terminal, and the second input terminal of the device is connected to the second output terminal of the said source . In the prototype, the first clamp of the reactor is connected both to the second clamp of the input capacitor and to the second output clamp of the device. The second reactor terminal is connected to the second input terminal of the device. Here, the reactor functions as a current-limiting element. Another possible variation of such an element is a starting resistor.

The circuit connecting the input terminals of the prototype with the output terminals of the DC voltage source is made in the same way as the similar circuit of the first analogue described above. The prototype differs from the first analogue mentioned above by the presence of a reactor, which, due to its current-limiting effect, reduces the maximum value of the current charging the capacitor. At the same time, the manifestations of the indicated drawback of this analogue are reduced: it is possible to select a reactor inductance such that the apparatus for current protection of the inverter power line will not be damaged by the charging current of the inverter input capacitor. The use of the reactor does not change the energy loss in the elements of the capacitor charge circuit. But the heating of the conductors of the line connecting the input of the voltage inverter to the DC voltage source becomes less than in the case of the first analogue, since most of the energy loss will be released in the reactor winding.

, где U - напряжение источника, а L_Σ - сумма индуктивностей питающей линии и реактора.) Это преимущество реактора позволяет вводить в содержащую реактор цепь заряда электронные ключи с относительно небольшим допустимым значением производной проходящего через эти ключи тока. Существующие электронные ключи могут не обеспечить включения цепи с пусковым резистором при больших зарядных токах конденсатора. В-третьих, при одинаковых максимальных значениях зарядного тока конденсатора, первое достижение равенства напряжений конденсатора и источника при использовании зарядной цепи с реактором произойдет в несколько раз быстрее, чем конденсатор практически зарядится до напряжения источника при использовании зарядной цепи с пусковым резистором.The use of a reactor as a current-limiting element is associated with the achievement of three advantages compared to the other variant of the current-limiting element, in which the reactor is replaced by a starting resistor. Firstly, such a resistor has a relatively high resistance, and it, after the end of the process of charging the capacitor, must be excluded from the input circuit of the inverter to avoid a significant decrease in the input voltage and inverter. The reactor, in steady-state operating modes, can not be removed from the input circuit of the inverter, since its active resistance is much less than that of the starting resistor. Secondly, at the same maximum values of the charging current of the capacitor, the maximum value of the derivative of this current when using the reactor is tens and hundreds of thousands of times less than when using a starting resistor. (The greatest derivative of the charging current takes place at the first moment after the closure of the charging circuit, it is equal to

, where U is the voltage of the source, and L _Σ is the sum of the inductances of the supply line and the reactor.) This advantage of the reactor allows introducing electronic keys with a relatively small permissible derivative of the current passing through these keys into the charge circuit containing the reactor. Existing electronic keys may not provide the inclusion of a circuit with a starting resistor at high charging currents of the capacitor. Thirdly, at the same maximum values of the charging current of the capacitor, the first achievement of the equality of the voltage of the capacitor and the source when using the charging circuit with the reactor will occur several times faster than the capacitor is practically charged to the voltage of the source when using the charging circuit with a starting resistor.

, гдеThe prototype with the second analogue is united by a common feature - the presence of a series resonant circuit composed of a reactor and a capacitor. The prototype device is much simpler than the second analogue. The prototype has only one capacitor, there is no transformer and inverter supplying the resonant circuit. The clamps of the resonant circuit are connected to the output clamps of the source constantly, but do not switch, as in the second prototype. Therefore, the process of charging a capacitor included in the output of the device is continuous, and not cyclic. The charging current of the capacitor throughout the charging process takes the form of a sinusoid. Its amplitude decreases exponentially with a time constant that is equal to

where

R _Σ is the sum of the active resistances of the supply line and the reactor. The capacitor charge is completed in a time equal to four to five values of the specified time constant. This time is several periods of charging current.

The known device for connecting a stand-alone voltage inverter to a DC voltage source (prototype) in addition to its advantages (reducing the amplitude of the charging current of the capacitor) has a significant drawback. It lies in the fact that by the end of the first half of the charging current period, the capacitor voltage reaches its maximum and becomes excessively large, close to the double voltage of the source. Because of this, it is required to use a capacitor with a rated voltage exceeding the indicated maximum voltage. As a result, the size, mass and cost of the capacitor will increase. The same remark applies to the choice of the rated voltage of the elements included in the electronic key block of the inverter. The second disadvantage is the large energy losses in the device and in the line by which it is connected to the voltage source that occur during charging of the inverter input capacitor. These losses are equal to the energy that the input capacitor stores during its charge. The second drawback is significant in cases where the connection of the voltage inverter to the voltage source occurs repeatedly and often enough, and during disconnection from the source, the capacitor is discharged. This not only reduces the efficiency of the electric power converter, which is an autonomous inverter, but also overheating and damage to the reactor are possible. The third disadvantage is the relatively large design power of the reactor, which is equal to the product of the reactor inductance by the average of the effective value of its charging current during the charge of the input capacitor. The last value determines the heating of the reactor winding, to reduce it when using the prototype there is only one possibility - this is to increase the inductance of the reactor.

The task to which the invention is directed is to improve the quality of the charge process of the inverter input capacitor: limiting the maximum values of the charging current of the inverter input capacitor to an acceptable level when using such a reactor inductance, which in the prototype corresponds to a significantly larger amplitude value of this current; reduction of overvoltages at the input capacitor and other elements of the autonomous inverter and reduction of energy losses in the reactor and in the line connecting the input terminals of the autonomous voltage inverter to the DC voltage source.

This object is achieved in that in a device for connecting an autonomous voltage inverter to a DC voltage source, containing a reactor and an input inverter capacitor, the first terminal of which is connected to the first input and output terminals of the said device, while the first output terminal of this device is connected to the first input the terminal of the stand-alone voltage inverter, and the first input terminal of this device is connected to the first output terminal of the DC voltage source, the first the inlet terminal of said inverter and the first output terminal of said source have the same polarity, the second terminal of the inverter input capacitor is connected to the second output terminal of this device, which is connected to the second input terminal of the specified inverter, and to the first reactor terminal, and the second input terminal of the device is connected to the second an output terminal of said source, a damping circuit is introduced, comprising the first and second resistors in series and a damping capacitor and which is connected to the device between its first and second input terminals, as well as three switches, an inverter input capacitor charge control unit, an input capacitor current transducer and two diodes, the first of which is connected between the first output terminal of the device and the second reactor terminal, and the second diode is connected between the second output terminal of the device and the first terminal of the reactor, while both diodes are connected in a direction that is not conductive with respect to the voltage of said source, a current measuring transducer an input capacitor is connected between the second terminal of the input capacitor and the first terminal of the reactor, the first and second switches are connected in parallel with the first resistor and the second diode, the third switch is connected between the second terminal of the reactor and one of the output terminals of the specified autonomous inverter, and the output of the charge control unit of the input inverter capacitor connected to the control input of the electronic key of the specified autonomous inverter, which is connected between the second input terminal and the specified odnym terminal of this inverter.

The task is also achieved by the fact that the charge control unit of the inverter input capacitor contains a command element, measuring transducers of the DC source voltage and inverter input capacitor voltage, a storage unit, a comparator, an electronic key control unit and a fourth switch connected between the output of the electronic key control unit and the output of the specified block control the charge of the input capacitor of the inverter, the inputs of the measuring voltage converters and the voltages of the inverter input capacitor are connected respectively to the first and second input terminals of the device and to the first and second terminals of the inverter input capacitor, and the first output of the command element, the output of the input capacitor measuring current transducer, respectively, are connected to the first, second, and third inputs of the electronic key control unit and the first output of the comparator, in which the second output is connected to the first input of the storage unit, and the first and second inputs are connected respectively to the outputs give transducer input capacitor voltage and the memory block, whose second input is connected to the second output of the command element, and a third input connected to the output of the transmitter of said source voltage.

The task is also achieved by the fact that as a damping circuit and the first switch, a unipolar silicon voltage limiter is used, the anode of which is connected to that of the input terminals of the device, which is connected to the terminal of the DC voltage source having a negative polarity, and the cathode of the specified voltage limiter is connected to another input terminal of the device.

The task is also achieved by the fact that as a damping circuit and a first switch, a group of series-connected unipolar silicon voltage limiters is used, the anode of each subsequent them being connected to the cathode of each previous one, and the anode of the first unipolar silicon voltage limiter connected to that of the terminals of the device, which connected to a negative polarity terminal of a DC voltage source.

Distinctive features of the proposed solutions perform the following functional tasks.

Signs: “a damping circuit is introduced into the device for connecting a stand-alone voltage inverter to a DC voltage source, which contains the first and second resistors and a damping capacitor in series and which is connected between its first and second input terminals ...” - allow when the electronic switch goes into off state close the current of the line connecting the DC voltage source to the input of the autonomous inverter through the damping circuit, while reducing the overvoltage and possibly damage to the electronic key that could have occurred in the absence of a damping circuit due to the energy stored in the inductance of the specified line.

Signs: “two diodes are introduced into the device for connecting an autonomous voltage inverter to a DC voltage source ... the first diode is connected between the first output terminal of the device and the second terminal of the reactor, and the second diode is connected between the second output terminal of the device and the first reactor terminal, while both diodes are turned on in a direction that is not conductive with respect to the voltage of the mentioned source ”- allow to reduce energy losses in the reactor. Through the first diode, the reactor current closes when the electronic switch is turned off, if the voltage of the inverter input capacitor has not yet reached the value of the DC source voltage. In this case, most of the energy stored in the reactor by the time the electronic switch is turned off is transferred to the input capacitor of the inverter, increasing the voltage of this capacitor. If the voltage of the indicated capacitor reaches the value of the source voltage, then the second diode will begin to conduct current, returning most of the energy stored in the reactor by the time the voltage equality of the indicated capacitor and the direct current source is reached, to this source.

Signs: "three switches ... are inserted into the device for connecting an autonomous voltage inverter to a DC voltage source ..." and "... the first switch is connected in parallel with the first resistor ..." - allow you to change the active resistance of the damping circuit. When the device input is connected to a DC voltage source, the first switch is in the off position, and the maximum value of the indicated active resistance, equal to the sum of the resistances of the first and second resistors, limits the current charging the damping capacitor to the required level. In the process of charging the input capacitor of the inverter, the first switch is in the on position, and the minimum value of the indicated active resistance, equal to the resistance of the second resistor, limits at the required level the overvoltage that occurs when the electronic switch is turned off.

Signs: "three switches ... are inserted into the device for connecting the autonomous voltage inverter to the DC voltage source ..." and "... the second switch is connected in parallel ... to the second diode, the third switch is connected between the second terminal of the reactor and one of the output terminals of the specified autonomous inverter ..." - make it possible to use the electronic key in the inverter in the process of charging the input capacitor of the inverter, and after the end of the charge of the input capacitor to exclude the specified electronic circuit from its circuit th key and connect the capacitor to the input of the autonomous inverter.

Signs: "a device for connecting a stand-alone voltage inverter to a DC voltage source has been introduced ... a charge control unit of the input inverter capacitor ..." and "... the output of the charge control unit of the input inverter capacitor is connected to the control input of that electronic key of the specified stand-alone inverter, which is connected between the second input terminal and the specified output terminal of this inverter "- allow you to control the process of charging the input capacitor of the inverter using an electronic key, by entering its part of the inverter.

Signs: “... the inverter input capacitor charge control unit contains a command element, measuring transducers of the DC source voltage and inverter input capacitor voltage, a storage unit, a comparator, an electronic key control unit and a fourth switch connected between the output of the electronic key control unit and the output of the specified unit charge control of the inverter input capacitor, inputs of the measuring transducers of the source voltage and input condensate voltage the inverter are connected respectively to the first and second input terminals of the device and to the first and second terminals of the input capacitor of the inverter, and the first output of the command element, the output of the input capacitor current measuring transducer and the first output of the comparator are connected respectively to the first, second and third inputs of the inverter in which the second output is connected to the first input of the storage unit, and the first and second inputs are connected respectively to the outputs of the measuring transducer I voltage of the input capacitor and the storage unit, in which the second input is connected to the second output of the command element, and the third input is connected to the output of the voltage measuring transducer of the mentioned source ”- allow you to start the process of charging the input capacitor by sending a command to turn on the electronic key for the first time and turn off the electronic key when the charge current of the capacitor reaches the maximum allowable value. This value of the charge current is much less than the amplitude value of this current, which would have occurred if the electronic key had not been turned off before the end of the capacitor charge. Therefore, turning off the electronic at an acceptable maximum value of the charging current makes it possible to reduce the inductance of the reactor and, together with it, its mass and cost. These signs also allow you to turn on the electronic key when the charge current is reduced to a minimum value. The less the maximum and minimum values of the charging current differ, the less the ripple of this current and the closer its shape factor to unity. This reduces the heating of the reactor winding and the wires of the line connecting the autonomous inverter to the DC source. In addition, these signs allow you to interrupt the process of charging the input capacitor of the inverter at the moment when its voltage reaches the voltage value of the DC source. This eliminates the influence of voltage drop in the line connecting the DC source to the input of the device. The indicated voltage drop depends on the value and derivative of the charging current of the inverter input capacitor.

Signs: as a “damping circuit and the first switch, a unipolar silicon voltage limiter is used, the anode of which is connected to that of the input terminals of the device, which is connected to the negative voltage terminal of the DC voltage source, and the cathode of the specified voltage limiter is connected to the other input terminal of the device” - allow you to simplify the circuit to limit the voltage at the input of the device.

Signs: as a “damping circuit and the first switch, a group of series-connected unipolar silicon voltage limiters is used, the anode of each subsequent them being connected to the cathode of each previous one, the anode of the first unipolar silicon voltage limiter being connected to that of the input terminals of the device, which is connected to a negative the polarity of the clamp of the DC voltage source, and the cathode of the last of this group of series-connected unipolar silicon voltage limiters connected to another input terminal of the device ”- allow you to limit the voltage at the input of the device at high voltage source. These features can also provide a lower excess voltage level with respect to the voltage of the source, compared with the option in which one unipolar silicon voltage limiter is used.

The technical result that is achieved when solving the problem is expressed in the following. With the average values of the charging current of the input capacitor of an autonomous voltage inverter identical with the prototype, the distinguishing features of the proposed solution allow several times to reduce the following device parameters and indicators of the charging process of the input capacitor: reactor inductance and its mass; the deviation of the maximum values of the charging current from the average; the deviation of the maximum voltage values at the input capacitor and other elements of the autonomous inverter from the voltage of the DC source; energy losses in the reactor and in the line connecting the input terminals of the autonomous voltage inverter with a DC voltage source.

Based on the foregoing, we can conclude that the set of essential features of the claimed invention has a causal relationship with the achieved technical result, i.e. due to this combination of essential features of the invention, it became possible to solve the problem. Therefore, the claimed invention is new, has an inventive step and is suitable for use.

The invention is illustrated by the drawing, where: in Fig.1 shows a schematic diagram of a device for connecting an autonomous voltage inverter to a DC voltage source, in which a damping circuit is used to limit overvoltages; figure 2 and figure 3 shows fragments of circuit diagrams of such devices in which, to limit overvoltages, respectively, a unipolar silicon voltage limiter and a group of series-connected unipolar silicon voltage limiters are used. Figure 1, as an example, shows a diagram of a three-phase bridge inverter. Six inverter electronic keys are shunted by reverse diodes. As electronic keys, transistors or fully controlled thyristors can be used.

The device 1 for connecting a stand-alone inverter 2 voltage to a source of DC voltage 3 contains the following main elements: reactor 4, the input capacitor 5 of the inverter and the charge control unit 6 of the input capacitor of the inverter. The first 7 and second 8 output terminals of the device 1 are connected respectively to the first 9 and second 10 input terminals of the inverter 2, as well as to the first 11 and second 12 input terminals of the device 1. The terminals 11 and 12 are connected respectively to the first 13 and second 14 of the source 3 s using line 15, which may include an apparatus not shown in FIG. 1 for switching on and protecting this line. The first clamps 7, 9, 11 and 13 of the device 1, inverter 2 and source 3 have the same polarity, in FIGS. 1, 2 and 3, the polarity of these clamps is negative. The polarity of the second clamps 8, 10, 12 and 14 is positive.

The device 1 also includes a circuit 16 for overvoltage limiting, which is shown in FIG. 1 in the form of a damping circuit containing the first 17 and second 18 resistors and a damping capacitor 19. A first switch 20 is connected in parallel with the first resistor 17. The circuit 16 is connected between the input terminals 11 and 12 of the device 1. The capacitor 5 is connected with its first terminal 21 to the output terminal 7 of the device 1, and the second terminal 22, through the current transducer 23 of this capacitor, to the first terminal 24 of the reactor 4. The second terminal 25 of the reactor 4 is connected through h the first diode 26 to the output terminal 7 of the device 1, and the first terminal 24 of the reactor 4 is connected through the second diode 27 to the output terminal 8 of the device 1. The diodes 26 and 27 are connected in a direction that is not conductive with respect to the voltage of the source 3. The second switch 28 is connected parallel to the diode 27. The third switch 29 connects the second terminal 25 of the reactor 4 to one of the output terminals 30 of the inverter 2. This switch together with the reactor 4, the current measuring transducer 23, the capacitor 5 and the electronic key 31 of the inverter 2, together with the key 31 connected in parallel the reverse diode 32, form a charge circuit of the capacitor 5. This circuit is connected to the output terminals 7 and 8 of the device 1.

The inverter input capacitor charge control unit 6 comprises a command element 33, DC / DC voltage measuring transducers 34 and 35, an inverter input capacitor voltage, a storage unit 36, a comparator 37, an electronic key control unit 38 and a fourth switch 39. This switch connects the output of the unit 38 control of the electronic key with the output 40 of the block 6 control the charge of the capacitor 5. The output 40 is connected to the control input of the electronic key 31. The inputs of the voltage measuring transducers 34 and 35 are connected respectively to the first 11 and second 12 input terminals of the device 1 and to the first 21 and second 22 terminals of the capacitor 5. The first output of the command element 33, the output of the transducer 23, respectively, are connected to the first, second and third inputs of the electronic key control unit 38 the current of the capacitor 5 and the first output of the comparator 37. The second output of the comparator 37 is connected to the first input of the storage unit 36, and the first and second inputs of the comparator 36 are connected respectively to the outputs of the measuring transducer 3 5 of the voltage of the input capacitor 5 and the storage unit 36. The second input of the storage unit 36 is connected to the second output of the command element 33, and the third input of the storage unit 36 is connected to the output of the voltage transducer 34 of the source 3.

Circuit 16 for surge protection can be performed in the simplest manner, as shown in figure 2. It in this case consists of one element - a unipolar silicon voltage limiter 41. The anode and cathode of the limiter 41 are connected respectively to the first 11 and second 12 input terminals of device 1. (The name “unipolar silicon voltage limiter” also has synonyms: “protective diode” or “suppressor”, and the term “transient voltage surge suppressor” is used abroad or abbreviated TVSS.) The circuit 16 for surge suppression can also be made in the form of several unipolar silicon voltage limiters 41 connected in series in the same direction, as shown in FIG. 3.

A device for connecting a stand-alone voltage inverter to a DC voltage source, the circuit diagram of which is shown in figure 1, operates as follows.

, гдеBefore connecting to the source 3, the voltages of the capacitors 5 and 19 are zero, and all four switches 20, 28, 29 and 39 are open. All electronic keys of inverter 2 are also in open state. When line 15 is connected to source 3, the voltage of which is U, the charging process of damping capacitor 19 begins. The capacitance C _{d of} this capacitor is hundreds and thousands of times smaller than the capacitance C of the input capacitor 5 of the inverter. The inductance and resistance of line 15 are negligible. In this case, the maximum value of the charging current of the capacitor 19 is determined by the approximate formula:

where

R ₁ and R ₂ are the resistances of the first 17 and second 18 resistors. After the charging process of the capacitor 19, its voltage is equal to the voltage U of the source 3. This voltage, measured by the measuring transducer 34, is stored in the memory of the storage unit 36. The output signals of the current transducers 23 and 35 of the voltage of the capacitor 5, as well as the comparator 37 are equal to zero. Switches 20, 29 and 39 are brought into a closed state. The switch 20 shunts the resistor 17, while the active resistance of the damping circuit 16 is reduced to R ₂ - the resistance of the resistor 18. Closing the switches 29 and 39 completes the preparation for the start of the process of charging the main capacitor 5. This process begins with the action on the command element 33, which through the block 38 control the electronic key 31 and the switch 39 provides a signal to turn on the key 31. At the same time, the command element supplies a signal to the second input of the storage unit 36. As a result, the storage unit will save the last Before closing the key 31, the value U ₀ of the source voltage will stop monitoring the voltage at the input terminals 11 and 12 of device 1. (The last voltage changes with a change in the charging current due to a voltage drop in the line.) With the appearance of the current and voltage of the capacitor 5, the output starts to change the signals of the measuring transducers 23 and 35. If we neglect the very small effect of the voltage drop on the line 15, which also allows us not to take into account the influence of the damping circuit 16 on the current and voltage of the capacitor 5, the Laplace image dnyh processes of charging current I _C (s) and the voltage U _C (s) of the capacitor can be described generally by the following expressions:

where s is the argument of the image of the time functions t, L is the inductance of the reactor 4, R is its active resistance, U _C0 is the initial voltage of the capacitor 5, I _C0 is the initial current of the reactor. When you first turn on the electronic key 31, the last two values are equal to zero. In this case, the following transition characteristic expressions obtained from (1) using the inverse Laplace transform are valid:

- постоянная времени реактора,

- волновое сопротивление последовательного резонансного контура,

- резонансная угловая частота этого контура. Из-за наличия в этом конуре сопротивления R угловая частота колебаний ω несколько ниже резонансной.Where

is the time constant of the reactor,

- wave impedance of the series resonant circuit,

is the resonant angular frequency of this circuit. Due to the presence of resistance R in this circuit, the angular oscillation frequency ω is slightly lower than the resonance frequency.

. Если С=0,6 Ф, L=0,6 Гн, R=0,6 Ом, то эта величина равна 0,56, что при U=800 В составляет около 450 В. Второй недостаток - большие потери энергии в реакторе. При пренебрежении активным сопротивлением линии, для приведенных значений напряжения источника и емкости конденсатора они составят 192 кДж.Expressions (2) and (3) determine the oscillatory process. The direction of the current in the charge circuit changes every half of the period of the angular frequency ω. With a positive direction of this current, it passes through an electronic switch 31, the source 3 gives off power, and the voltage of the capacitor 3 rises. The negative current passes through a reverse diode connected in parallel with the electronic switch 31. In this case, the capacitor 5 is discharged, and the source 3 consumes power. This process ends if the key 31 is not open, after 8-10 time constants τ of reactor 4. Similarly, with the possible absence of an electronic key and a reverse diode bypassing it, charge processes of the input capacitor in the prototype occur. The first disadvantage of the oscillatory transient charge of the capacitor 5 is the large values of the excess voltage of the capacitor 5 over the voltage of the source. The maximum of these excesses occurs after half the period of the angular frequency ω. Its relative value (the base value is the voltage of the source) is

. If C = 0.6 F, L = 0.6 H, R = 0.6 Ohms, then this value is 0.56, which at U = 800 V is about 450 V. The second drawback is the large energy loss in the reactor. If the line resistance is neglected, for the given values of the source voltage and capacitor capacitance they will be 192 kJ.

лишь немногим меньше энергии конденсатора при его заряде до напряжения источника, а напряжение на втором зажиме 25 реактора больше напряжения источника 3. Ток реактора при отключении ключа 31 не может мгновенно измениться и начинает замыкаться через диоды 26 и 27 и источник 3, если напряжение U этого источника не больше напряжения U₀, которое было на конденсаторе 5 в момент срабатывания компаратора. (Если напряжение U за время рассматриваемого процесса несколько увеличилось, то вначале ток реактора 4 будет подзаряжать конденсатор 5 до этого напряжения, а затем станет замыкаться через диод 27 и источник 3.) Направление тока в источнике 3 противоположно направлению его напряжения. Тем самым часть энергии, полученной от источника 3, возвращается обратно. Таким образом, устройство 1 является более экономичным, чем прототип, а в реакторе 4 выделятся в виде тепла меньшие потери энергии. Для рассматриваемого примера эти потери примерно равны 145 кДж, что составляет 76% от потерь энергии в реакторе прототипа. Время, в течение которого конденсатор 5 заряжается до напряжения источника 3, равно 0,44 с. Потери энергии, идущие на нагрев реактора, всего на 24% меньше, чем в неуправляемом процессе заряда конденсатора 5.If the maximum value I _{Cmax of the} charging current, which takes place through the fourth part of the period of the angular frequency ω (for the example under consideration, is about 1500 A) does not exceed the limit value I _C1 set in block 37, then the process of charging the capacitor 5 will continue for a little longer than this time at a charge current that is slightly less than the indicated maximum value. The charge of the capacitor 5 will stop when, for the first time, the voltage of the capacitor 5 reaches the initial voltage value U ₀ at the input terminals 11 and 12 of the device 1. At the same time, the comparator 37 will operate and its output signal through the block 38 and the switch 39 will command to turn off the key 31. K at this moment the energy of the magnetic field of the reactor

only a little less than the energy of the capacitor when it is charged to the voltage of the source, and the voltage at the second terminal 25 of the reactor is greater than the voltage of source 3. The current of the reactor when the key 31 is turned off cannot immediately change and starts to be closed through diodes 26 and 27 and source 3, if the voltage U the source is not more than the voltage U ₀ , which was on the capacitor 5 at the time the comparator was triggered. (If the voltage U has increased slightly during the process under consideration, then at first the current of the reactor 4 will charge the capacitor 5 to this voltage, and then it will become closed through the diode 27 and source 3.) The direction of the current in the source 3 is opposite to the direction of its voltage. Thus, part of the energy received from source 3 is returned back. Thus, the device 1 is more economical than the prototype, and in the reactor 4 less energy is lost in the form of heat. For the considered example, these losses are approximately equal to 145 kJ, which is 76% of the energy loss in the reactor of the prototype. The time during which the capacitor 5 is charged to the voltage of the source 3 is 0.44 s. The energy loss spent on heating the reactor is only 24% less than in an uncontrolled process of charging a capacitor 5.

The energy loss in the reactor 4 is proportional to the integral of the square of the current of the capacitor 5, and its voltage is proportional to the integral of this current in the first degree. Therefore, with constant parameters of the capacitor 5 and the reactor 4 and the same voltage of the source 3, to reduce the energy loss in the reactor 4, the maximum values of the charging current should be reduced. Device 1 implements this recommendation as follows. The electronic key 31 goes into the off state at the moment when the charging current in the first stage of the charge of the capacitor 5 becomes equal to the maximum limit value I _C1 set in block 37 and less than the maximum value IC _max . The second stage of the charge process of the capacitor 5 begins, at which the energy stored in the magnetic field of the reactor 4 is released. The current i _C (t) of the reactor 4 is closed through the capacitor 5 and the diode 26. The capacitor voltage is directed counter to the current i _C (t), which leads to a decrease in this current and an increase in the voltage of the capacitor 5. Simultaneously with the switching of the key 31 to the off state, the current of the line connecting the device 1 to the source 3 starts to pass not through the reactor 4, but through the damping circuit 16. Under the action of this current, the voltage at the input imah 11 and 12 of the device 1 increases abruptly and becomes high voltage source 3. Starting excess voltage at the input device 1 is equal to I _C1 R _2. By selecting the resistance R _{2 of the} second resistor, the desired overvoltage value can be sufficiently accurately provided. Next, a rapidly damping oscillatory process will begin, after which the line current will become zero, and the voltage at the input of device 1 will be equal to the voltage of source 3. It is advisable to choose a value of capacitance C _d such that the initial value of the derivative of the voltage at the input terminals of device 1 is zero. If this derivative is positive (with insufficient capacitance C _d ), then for some time the voltage at these terminals will increase and exceed the desired value of the overvoltage. If this derivative is negative, then the voltage at the input of device 1 will immediately begin to decrease, but the capacitance C _d will be more than the minimum necessary, and this will lead to an increase in the cost and mass of device 1.

Returning to the process of charging the main capacitor 5, we first consider the case when the minimum limit current value i _C (t) specified in block 38 is zero. The presence of a diode 26 prevents a change in the direction of current i _C (t). Therefore, the second stage of the process of changing the current i _C (t) ends when this current becomes equal to zero. Most of the energy stored in the reactor 4 will go into the capacitor 5, increasing its voltage. At the moment when the current i _C (t) becomes equal to zero, block 37 gives a signal to turn on the electronic key 31. The second cycle begins, in which at the first stage the key 31 is closed and the current i _C (t) increases to the value I _C1 , and in the second stage, this switch opens, and the current I _C1 drops to zero. These cycles are repeated until, at the first or second stage, the voltage u _C (t) rises to the value that is stored in the memory of block 36. In this case, the comparator 37 will send through block 38 one signal to turn off the key 31, and to the first input of the memory block 36 is another signal that will transfer this block from the mode of storing the initial value of the voltage of the source 3 to the tracking mode of this voltage. If the voltage of the capacitor 5 at the first stage of a cycle reaches the value stored in the memory of block 36, then the current of the reactor 4 begins to be closed through diodes 26 and 27 and source 3, as described above. If the voltage of the capacitor 5 reaches the voltage at the input terminals 11 and 12 of the device 1 in the second stage of any cycle, the current of the reactor will be closed by a circuit containing diodes 26 and 27, the power line of the device 1 and source 3. In this case, most of the energy accumulated in the reactor 4, will return to source 3.

The smaller the current value I _C1 , the less energy loss in the reactor, and the number of cycles and the charge time of the capacitor with a decrease in I _C1 increase. So, for the considered example (U = 800 V, C = 0.6 μF, L = 0.1 H, R = 0.15 Ohm) at I _C1 = 900 A, the charge of the capacitor 5 to 800 V will end at the first stage of the second cycle 0.85 s after the start of its charge. In this case, the energy loss in the reactor will be 51.7 kJ, which is 3.7 times less than in the prototype. When I _C1 = 800 A, the charge of the capacitor 5 to 800 V will be completed later, in the first stage of the third cycle, 1.22 s after the start of its charge. The energy loss in the reactor will be 37.2 kJ, which is 1.4 times less than when I _C1 = 900 A and 5.2 times less than in the prototype.

It is possible to further reduce the energy loss in the reactor 4 at the same total charge time of the capacitor 5. For this, the maximum minimum value of I _C2 , at which the key 31 is turned on again, must be made not equal to zero, but close to I _C1 . The minimum loss is achieved in an unattainable limit in practice - when the equality I _C2 = I _C1 is fulfilled. (There are no ripples in the charging current, and the number of key on and off cycles is infinitely large.) With the same as in the last example, the charge time of the capacitor 5 (1.22 s), the current I _{C1 is} approximately 400 A, and the energy loss in the rheostat will decrease by 1.3 times and amount to 28.4 kJ (6.8 times less than in the prototype). If the inductance of the reactor 4 is reduced, then its active resistance will also decrease. Energy losses will decrease in proportion to the resistance of the reactor. The practical implementation of recommendations for reducing the reactor inductance and bringing I _C2 closer to I _C1 has two limitations. The first of these is the permissible maximum frequency of switching on the electronic key. The second is the minimum time it takes to perform a number of operations: measuring the current value of current i _C (t), comparing it with the set limits I _C1 and I _C2 , signaling to change the state of the electronic key and executing this command.

The damping circuit 16 can be replaced by a unipolar silicon voltage limiter 41, as shown in FIG. 2, or by several of these limiters in series (FIG. 3). The latter option can be used in two cases. First, when the voltage of source 3 is greater than the largest of the nominal voltages available unipolar silicon voltage limiters. Secondly, when the sum of the rated voltages of several unipolar silicon voltage limiters is closer to the voltage of the source than any one limiter. According to its principle of operation, several series-connected limiters (protective diodes) can be replaced by one whose rated voltage is equal to the sum of the rated voltages of each of the series-connected protective diodes. The unipolar silicon voltage limiter is a semiconductor diode with an avalanche reverse voltage-current characteristic. When using the limiter (s) 41 at the preliminary stage, before the start of the process of charging the capacitor 5, the need to turn on the switch 20 disappears. (This switch is absent in this embodiment of the device 1.) There is no charge stage of the damping capacitor 19. The first stage of each charge cycle of the capacitor 5 proceeds as shown above. In the second stage of each cycle, the main process — reactor discharge 4 — proceeds in the same way as in the presence of a damping circuit. The discharge of the inductance of the line 15 to the voltage limiter 41 has insignificant differences from the above. A piecewise-linear (simplified) equivalent circuit of a unipolar silicon voltage limiter consists of an EMF E equal to the voltage at which the avalanche breakdown of this device begins, and a resistor connected in series with it, the resistance of which is equal to the differential inverse resistance R _{din of the} protective diode 41 (for several in series included protective diodes - the sum of these resistances of all diodes). EMF E is 10% or more higher than the rated voltage U _RM in the static mode of operation, and this voltage should be no less than the voltage U of source 3. Resistance R _din performs the function of resistance R _{2 of} resistor 18 in the damping circuit. The role of the capacitor 19 is played by the emf source E, but there are the following differences. Firstly, the initial voltage of the capacitor 19 was equal to the voltage U, and the EMF E is greater than this voltage by at least 10%. Secondly, the capacitor voltage changes according to the oscillatory law, returning to the initial value, and the EMF E remains constant up to the zero value of the line inductance current 15. That is, the discharge process of this inductance occurs monotonously and faster than in the presence of a damping circuit. This nature of this process indicates the advantage of using a unipolar silicon voltage limiter 41, in comparison with the damping circuit 16. Another advantage is that the size and mass of such a limiter are smaller than the sum of the similar parameters of the elements of the damping circuit and switch 20. The disadvantage of using the limiter 41 voltage is a rather large initial (when turning off the key 31) voltage at the terminals 11 and 12 of the device 1. It is 1.5 times or more superior to U _RM and, especially, the voltage U. In this regard, protective diodes are superior to varistors, in which the initial voltage is two times or more higher than the nominal voltage of the varistor in the static mode of operation, but inferior to the damping circuit 16. The use of a damping circuit 16, which can provide a smaller excess voltage at terminals 11 and 12 device 1, allows, in some cases, to choose with lower values of the nominal voltage of the capacitor 5, as well as electronic keys and inverse diodes of the inverter.

After the operation of the comparator 38 and the end of the discharge process of the reactor 4, the following actions are performed. The circuit breaker 20 is opened, preparing the device 1 for the next connection to the source 3. The circuit breakers 29 and 39 are opened, thereby opening up the possibility of the electronic switch 31 working as part of the inverter 2. The circuit breaker 28 is closed, which allows the diode 27 to be shorted. Power losses in the diode are eliminated. 27, and it is possible to pass the alternating current generated by the inverter 3 in its input circuit through the capacitor 5. After performing these manipulations, the inverter 2 is ready to connect the load to the output terminals 30 and power e ac. The constant component of the input current of the inverter 2 goes to its input terminals 9 and 10 directly from the source 3, bypassing the reactor 4. This feature distinguishes device 1 from its prototype. Thus, the operation of the inverter 2 eliminates the loss of power and voltage in the reactor 4, which increases the efficiency of converting direct current to alternating current. The reactor 4, operating briefly, only during the charge of the capacitor 5 (this time does not exceed several seconds), can be performed with high current densities in the reactor winding. This possibility provides a multiple reduction in the mass of the reactor 4, compared with the reactor of the prototype.

After the operation of the inverter 2, the switch 28 is transferred to the open state. Device 1 is ready for a new connection to source 3 and a new process for charging capacitors 19 and 5. If the interruption in connecting device 1 to source 3 was short, then capacitors 19 and 5 may not completely discharge. This circumstance will not complicate the considered process of carrying out both preparatory operations (changing the state of switches 20, 28, 29 and 39) and the charge of capacitor 5, only the charge time of capacitors 19 and 5 will become less.

Information sources

1. Electrical Engineering: Textbook for universities. - In 3 books. Book II. Electric cars. Industrial Electronics. Theory of Automatic Control / Ed. P.A. Butyrina, R.Kh. Gafiyatullina, A.L. Shestakova. - Chelyabinsk: Publishing House of SUSU, 2004. - 711 p.

2. Electrotechnical directory: V 3 T. 2. Electrotechnical products and devices / Under the general. ed. professors MPEI: I.I. Orlova (chap. ed.) and others - M .: Energoatomizdat, 1988 .-- 880 p.

3. V.I. Meleshin. Transistor converter technology. - M .: Technosphere. - 2005 .-- 632 s.

4. Zinoviev G.S. Fundamentals of Power Electronics: A Textbook. - Novosibirsk: Publishing House of the NSU, 2000 - Part 2 - 197 p. (prototype).

Claims (3)

1. A device for connecting an autonomous voltage inverter to a DC voltage source, comprising a reactor and an inverter input capacitor, the first terminal of which is connected to the first input and output terminals of the said device, while the first output terminal of this device is connected to the first input terminal of the autonomous voltage inverter, and the first input terminal of this device is connected to the first output terminal of the DC voltage source, the first input terminal of the specified inverter and the first the output terminal of said source have the same polarity, the second terminal of the input inverter capacitor is connected to the second output terminal of this device, which is connected to the second input terminal of the specified inverter, and to the first terminal of the reactor, and the second input terminal of the device is connected to the second output terminal of the source, characterized in that a damping circuit is introduced into the device, comprising first and second resistors in series and a damping capacitor, and which is connected between the first and second input terminals of the device, as well as three switches, an inverter input capacitor charge control unit, an input capacitor current transducer and two diodes, the first of which is connected between the first output terminal of the device and the second reactor terminal, and the second diode is connected between the second output terminal device and the first clamp of the reactor, while both diodes are connected in a direction that is not conductive with respect to the voltage of said source, a measuring current transducer of input a capacitor is connected between the second terminal of the input capacitor and the first terminal of the reactor, the first and second switches are connected in parallel with the first resistor and the second diode, the third switch is connected between the second terminal of the reactor and one of the output terminals of the specified autonomous inverter, and the output of the charge control unit of the input inverter capacitor is connected with the control input of the electronic key of the specified autonomous inverter, which is connected between the second input terminal and the specified output th of this inverter. 2. A device for connecting an autonomous voltage inverter to a DC voltage source, comprising a reactor and an inverter input capacitor, the first terminal of which is connected to the first input and output terminals of the said device, while the first output terminal of this device is connected to the first input terminal of the autonomous voltage inverter, and the first input terminal of this device is connected to the first output terminal of the DC voltage source, the first input terminal of the specified inverter and the first the output terminal of said source have the same polarity, the second terminal of the input inverter capacitor is connected to the second output terminal of this device, which is connected to the second input terminal of the specified inverter, and to the first terminal of the reactor, and the second input terminal of the device is connected to the second output terminal of the source, characterized in that a damping circuit is introduced into the device, which uses a unipolar silicon voltage limiter or a group of series-connected to belt voltage limiters, and which is connected between the first and second input terminals of the device, as well as two switches, an inverter input capacitor charge control unit, an input capacitor current transducer and two diodes, the first of which is connected between the first output terminal of the device and the second reactor terminal, and a second diode is connected between the second output terminal of the device and the first reactor terminal, both diodes being turned on in a direction not conducting with respect to the voltage mentioned of the source, the input capacitor current transducer is connected between the second terminal of the input capacitor and the first terminal of the reactor, the first switch is connected in parallel with the second diode, the second switch is connected between the second terminal of the reactor and one of the output terminals of the specified autonomous inverter, and the output of the charge control unit of the input inverter capacitor connected to the control input of the electronic key of the specified autonomous inverter, which is connected between the second input terminal and specified output terminal of this inverter. 3. The device according to each of claims 1 and 2, characterized in that the charge control unit of the input inverter capacitor contains a command element, measuring transducers of the DC voltage and voltage of the inverter input capacitor, a storage unit, a comparator, an electronic key control unit and a fourth switch connected between the output of the electronic key control unit and the output of the specified inverter input capacitor charge control unit, the inputs of the voltage measuring transducers the source and voltage of the inverter input capacitor are connected respectively to the first and second input terminals of the device and to the first and second terminals of the inverter input capacitor, and the first output of the command element and the output of the input capacitor current measuring transducer are connected to the first, second and third inputs of the inverter and the first output of the comparator, in which the second output is connected to the first input of the storage unit, and the first and second inputs are connected respectively but to the outputs of the voltage measuring transducer of the input capacitor and the storage unit, in which the second input is connected to the second output of the command element, and the third input is connected to the output of the voltage measuring transducer of the said source.

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