RU2279748C1 - Device for charging an accumulating capacitor - Google Patents

Abstract

FIELD: pulse engineering, in particular, capacitive accumulators of electric energy; possible utilization for realization of methods of so-called "slow" charging during several periods of feeding voltage, for charging capacitive accumulators of electric energy, generators of powerful pulses.

SUBSTANCE: current-limiting batching elements are made in form of inductance coils, bridge transformer is made in form of autonomous voltage inverter based on lockable keys, to outputs of three-phased power source, inputs of three-phased network voltage indicator are connected, outputs of which are connected to some inputs of control block, inputs of three-phased bridge transformer are additionally connected to inputs of phase current indicators, outputs of which are connected to other inputs of control block, to output of three-phased bridge transformer voltage indicator of capacitive accumulator is connected, output of which is connected to other input of control block, to another input of control block, output of block for setting voltage value of accumulator is connected, and to yet another input of control block, output of block for setting speed of accumulator charging is connected. Principles utilized for building control system make it possible to realize in broad spectrum the smooth adjustment of charging speed of capacitive accumulator, while current of practically sinusoidal shape is consumed from the network, and utilization of inductors instead of current-limiting batching capacitors increases reliability of device.

EFFECT: increased charging speed of capacitive accumulator up to voltage, greatly exceeding amplitude of linear voltage of the network.

6 dwg

Description

The invention relates to a pulse technique and relates to capacitive storage of electrical energy. It can be used in the implementation of the methods of the so-called "slow" charge for several periods of supply voltage, for charging capacitive electric energy storage devices (UNEE), high-power pulse generators.

A device for charging a capacitive energy storage device containing a three-phase AC source with three terminals, a capacitive energy storage device, a first metering capacitor, a second metering capacitor, one lining of which is connected to the first output of a three-phase AC source, a charging thyristor, the cathode of which is connected to the first output capacitive storage, four valves, the anode of the first valve is connected to one lining of the first metering capacitor, the cathode of the second is connected to the third terminal of the three-phase of the alternating current source, the anode of the third is connected to the second terminal of the three-phase alternating current source and the system control unit, the first, second and third conclusions of which are connected to the first, second and third terminals of the three-phase alternating current source, and its fourth and fifth conclusions with the control transition a charging thyristor, additionally equipped with a linear inductor with two leads and a tap from a part of the turns of its winding, the first terminal of which is connected to another lining of the second metering capacitor, in the second output to the second output of the capacitive storage, and the outlet to the anode of the second valve, thyristors are used as the first, third and fourth valves, the anode of the charging thyristor is connected to the other plate of the first metering capacitor and to the cathode of the third thyristor valve, the cathode of the first thyristor valve is connected with the second terminal of the linear inductor, the anode of the fourth thyristor valve is connected to the third terminal of the three-phase AC source, and its cathode with the anode of the first thyristor valve, the sixth and seventh conclusions of the unit The system is connected to the control transition of the first thyristor valve, its eighth and ninth conclusions to the control transition of the third thyristor valve, the tenth and eleventh conclusions to the control transition of the fourth thyristor valve, the twelfth and thirteenth conclusions to the first and second conclusions of the capacitive storage, and the fourteenth and the fifteenth conclusions to one and the other plates of the second metering capacitor [1].

The disadvantages of this device are as follows: firstly, it provides a capacitive storage charge to a relatively low voltage (low specific energy indicators); secondly, the low rate of energy storage, as well as the lack of smooth regulation in a wide range of speeds (the rate of voltage growth on the plates of the storage capacitor) charge; thirdly, the consumption of current from the network with a high coefficient of non-sinusoidality; fourthly, the circuit design of the device does not allow the creation of a flexible high-speed control system.

The closest in technical essence to this invention is a device for charging a capacitive energy storage device containing a three-phase AC source with three output terminals, a three-phase two-half-wave bridge thyristor rectifier with two output terminals for connecting a storage capacitor and three input terminals, each of which is current-limiting the metering capacitor is connected to the output terminals of the AC source and the voltage monitoring and phase control unit the thyristors of the bridge rectifier are equipped with an additional thyristor, and the voltage control and phase control unit of the thyristors has an additional output that is connected to the control electrode, the cathode of the thyristor and one of the input terminals of the rectifier, while the positive output terminal of the rectifier is connected to the anode of this thyristor [2].

The disadvantages of this device are: firstly, the limited use due to the fact that it provides a capacitive storage charge up to a voltage 3 times the amplitude of the linear voltage of the source, which indicates low specific energy indicators (i.e., the ratio of power, energy to the mass of the charge device); secondly, the lack of a smooth and in a wide range of regulation of the charge speed of the capacitive storage; thirdly, an unsatisfactory form of current consumed from the mains; fourthly, the presence of less capricious in operation current-limiting-dosing capacitors.

The technical result of the invention is that, a device for charging a storage capacitor, comprising a three-phase power source, the outputs of which are connected to one terminal of three current-limiting-metering elements, the other terminals of which are connected to the inputs of a three-phase bridge converter, the outputs of which are connected to the storage capacitor, block control, the outputs of which are connected to the control inputs of a three-phase bridge converter, characterized in that, current-limiting-metering the elements are made in the form of inductors, the bridge converter is made in the form of an autonomous voltage inverter with lockable keys, the inputs of the three-phase power supply are additionally connected to the inputs of the three-phase network voltage sensor, the outputs of which are connected to one input of the control unit, the inputs of the three-phase bridge converter are additionally connected to the inputs of the sensors current of phases whose outputs are connected to other inputs of the control unit, yes connected to the output of a three-phase bridge converter the voltage sensor of the capacitive storage device, the output of which is connected to another input of the control unit, the output of the unit for setting the drive voltage is connected to the other input of the control unit, the output of the unit for setting the charge rate of the drive is connected to another input of the control unit.

Figure 1 shows the structural diagram of a device for charging a storage capacitor; figure 2 - schematic power diagram of the device in the first clock cycle; figure 3 - equivalent circuit of the proposed device, explaining its operation in the first cycle; figure 4 - equivalent circuit of the device, explaining his work in the second cycle; figure 5 is a structural diagram of a control unit, figure 6 is a graph obtained by simulating the operation of the device.

The block diagram of the device for charging the storage capacitor in figure 1 contains: a three-phase AC source 1 with three output terminals 2, 3 and 4, to which are connected the inputs of the three-phase voltage sensor of the network 5, the outputs of which are connected to the inputs of the control unit (BU) 6, the output terminals of the AC source are also connected to one terminal of the corresponding phase inductors 7 (phase A), 8 (phase B), 9 (phase C), the other terminals of the inductors 7, 8 and 9 are connected to one terminal of the current sensors 10, 11 and 12 (implementation of current feedback), the outputs of which are connected to other inputs of BU 6, other outputs of current sensors 10, 11, and 12 are connected to the input of an autonomous three-phase voltage inverter (AIN) 13, made on fully controlled keys (IGBT transistors) 14, 17, 19, 21, 23 and 25 with reverse diodes 15, 16, 18, 20, 22 and 24, a capacitive drive 28 is connected to the output terminals of the inverter 26 and 27, the plates of which are connected to the inputs of the drive voltage sensor 29, from the output of which a signal corresponding to the drive voltage is supplied to the control unit 6, control unit 6 also receives voltage reference signals I drive to the unit 30 and the charge storage unit 31 with the tempo.

A review of the operation of the device should be carried out, disassembling two clock cycles.

The first cycle according to the principle power circuit of the device (see figure 2) and equivalent circuit (see figure 3). To simplify the description, we assume that the capacitor 28 is already charged through the reverse diodes of the keys (the charge current circuit, and therefore, the diodes participating in the transient charge process, are determined by the instantaneous values of the phase voltage of the network at the time of connection of the AIN 13 to the alternating current network). The result of the transition process will be the presence on the plates of the capacitor 28 voltage, the potential of which is higher than the amplitude values of the line voltage of the network and the flow of current through the return diodes is impossible. From this moment, the charge storage process is controlled by control unit 6.

BU 6 controls the device with the fulfillment of priority requirements:

- consumption from a network of currents with a shape as close as possible to a sinusoidal one;

- device power factor close to unity;

- the ability to provide the highest possible speed of the process of energy storage in the drive.

We analyze the process of energy storage, for the beginning we take the time moment t ₁ corresponding to the moment of changing the sign of the voltage of phase A from the negative half-wave to the positive.

In Fig.3 we consider the first cycle of the device.

BU 6 generates control pulses for opening the transistors 17, 19 and 25. As a result, circuits are formed for the flow of a system of three-phase currents i ₂ (t), i ₃ (t), i ₄ (t).

In Fig. 3, the circuit for current i ₂ is 2-7-17-27-28-26-19-8-3, i.e. the voltage of the capacitor 28 is turned on in accordance with the linear voltage u ₂₃ (t) (hereinafter, the dotted line shows the element through which the current does not flow) and, as a consequence, the transient current i ₂ (t) is characterized by its growth. This process can be described by the equations:

where C is the capacity of the storage capacitor 28;

i _A (t) = i ₂ (t) instantaneous value of phase A current;

R _A is the active resistance of the inductor 7 phase A;

L _A - inductance of the inductor 7 phase A;

L _B - inductance of the inductor 8 phase B;

R _B - the active resistance of the inductor 8 phase;

u _AB (t) = u ₂₃ (t) is the line voltage between the phases of the AB.

Figure 3 shows the current flow circuit i ₄ (t) 4-9-25-27-28-26-19-8-3, i.e. the voltage of the capacitor 28 is turned on in accordance with the linear voltage U _BC , as a consequence, the transient current i ₄ (t) is characterized by its growth. This process can be described by the equations:

where i _C (t) = i _A (t) is the instantaneous value of the phase C current;

L _C - inductance of the inductor 9 phase C;

R _C is the active resistance of the inductor 9 phase C;

u _BC (t) = u ₃₄ (t) is the line voltage between the phases of the aircraft.

In Fig. 3, the circuit for current i ₃ (t) is two parallel branches of currents i ₂ (t) and i ₄ (t), therefore, the instantaneous value of current i ₃ (t) is equal to the sum of these currents:

The derivatives of the actual phase currents are quite high, as a result they will exceed the set current, the control unit 6 will work to reduce the phase current, namely, it will turn off the keys 17, 19 and 25. This moment is designated as t ₂ .

From this moment, the growth of phase currents ceases, and the energy of the magnetic field accumulated in the magnetic field of the inductors 7, 8 and 9 begins to maintain the current in the same direction. The direction of the currents for the phases will be preserved, but the chain of their flow in the AIN will change. In this case, the circuits for transmitting the energy of the magnetic field of the inductors are the reverse diodes of the keys.

Consider the second cycle of the device (see figure 4).

Figure 4 shows the circuit for the flow of current i ₂ (t) 2-7-15-26-28-27-20-8-3, i.e. the voltage of the capacitor 28 is turned on opposite to the linear voltage u ₂₃ (t), as a result, the transient current i ₂ (t) is characterized by its decrease. This process can be described by the equations:

In Fig. 4, the circuit for current i ₄ (t) is 4-9-22-26-28-27-20-8-3, i.e. the voltage of the capacitor 28 turns on opposite to the linear voltage U _BC , as a result, the transient process but the current i ₄ (t) is characterized by its decrease. This process can be described by the equations:

In Fig. 4, the circuit for current i ₃ (t) is two parallel branches of currents i ₂ (t) and i ₄ (t), therefore, the instantaneous value of current i ₃ (t) is equal to the sum of these currents according to expression (5).

The process of charging the storage capacity 28 is accompanied by a decrease in currents below predetermined values, the control unit 6 works to increase the phase currents, while it gives signals to open the keys 17, 19, and 25, then the processes are repeated.

Energetically, the process of accumulating electric energy in a capacitive storage is the following sequential processes: the first cycle is the accumulation of energy in the magnetic field of the inductors 7, 8 and 9, the second cycle is the transfer of this energy to the storage 28, i.e. the conversion of the energy of the magnetic field of the inductors 7, 8 and 9 into the energy of the electric field of the capacitor 28. During these two cycles, the stored energy in the capacitor will increase by:

where ΔU _C is the voltage increment on the plates of the capacitor 28.

, что в последующем такте отдачи приведет к увеличению отдаваемой энергии магнитного поля индукторов 7,8 и 9. Следующее приращение ΔU_C влияет на процесс аналогичным образом и так далее.In the next cycle of energy storage in the magnetic field of the inductors 7, 8 and 9, the previous increment ΔU _C to the voltage of the capacitor 28 will lead to an increase in the derivative currents

, which in the subsequent cycle of return will lead to an increase in the supplied energy of the magnetic field of the inductors 7.8 and 9. The next increment ΔU _C affects the process in a similar way and so on.

Thus, the accumulation is characterized by the process of "buildup" of the system of inductors 7, 8 and 9 of the accumulator 28, in which each previous accumulation cycle feeds the next. This allows us to conclude about the possibility of a half-period increase in the amplitudes of the phase currents:

where ΔI _m is the increment of the amplitudes of the phase currents.

This device uses the principle of accumulation with constant amplitudes of phase currents, while the functional dependence of the capacitance voltage on time u _C (t) is close to a hyperbole. The given amplitude of the phase currents determines the growth rate u _C (t). In this case, the maximum possible voltage of the storage capacitor, as well as the maximum accumulation rate, are determined by the acceptable characteristics of the elements of the device circuit, such as the maximum allowable current of transistors, the switching frequency, the maximum allowable voltage on the capacitance, etc.

Consider the work of BU 6 (see figure 5). BU 6 controls the current voltage value on the plates of the storage capacitance 28, comparing the signal proportional to this voltage u _Ck (t) supplied to input 32 with a given value U ^* _C supplied to input 33, the difference (U ^* _C -u _Ck (t)). The output of block 34 is connected to the input of the relay block 35, in which a logical signal is generated to block the supply of control pulses of the AIN keys and turn off the accumulation mode based on a comparison of the input value with a given setpoint. The output of block 35 is connected to SIFU AIN 36. The charge rate is determined by the magnitude of the amplitude of the phase currents, a signal proportional to the amplitude comes from block 31 to input 37 of the control unit 6. The formation of the specified phase currents is performed along three parallel branches. Consider the phase A current control channel. The task for each chain is to set the current amplitude I _m 37, which is fed to the inputs of the multiplication units 38, 39, and 40. The signal from the output of the conversion unit 41 comes to the second input of the block 38, and the signal 42 proportional to the voltage of phase A. The coefficient of block 41 is the ratio

where U _m.oc. - the amplitude of the feedback signal phase voltage.

As a result, the output of block 41 will receive a signal:

T.O. at the output of block 38:

The output of block 38 comes to the input of the comparison block 43, in which the value of the specified current is compared with the current feedback 44 i _2ist (t).

The output of block 43 goes to SIFU AIN 36.

The channels of currents i ₃ ^* (t), i ₄ ^* (t) work similarly.

When building BU 6 on the basis of microprocessor technology, high performance, accuracy, versatility and adaptability of the device are achieved, which greatly expands the scope of its application.

Figure 6 presents the simulation results of a three-phase controlled capacitive storage using the MatLab R12 6.0 program in the Simulink 4.0 package with the extension Power System Blockset.

In Fig. 6, during the simulation 0.1 s, the voltage across the plates of a capacitor with a capacity of 1000 μF exceeded the amplitude of the phase voltages by more than 20 times, while a practically sinusoidal current was consumed from the network (the time of uncontrolled spontaneous charge of the capacitance as a result of the transient process is insignificant, it is about 25% of the half-cycle of the supply voltage).

Thus, the replacement of current-limiting-dosing capacitors with make-up inductors and the use of lockable keys and reverse diodes connected in parallel with them in thyristors in a three-phase two-half-wave bridge controlled rectifier led to a change in the principle of energy storage in the drive, unlike the prototype. As a result, the presented device provides a high charge speed of a capacitive storage device to a voltage exceeding the amplitude of the line voltage of the network by several orders of magnitude, which indicates a high specific energy performance. The principles of BU 6 construction allow to realize a wide range of smooth regulation of the charge speed of a capacitive storage, while the current is consumed in a practically sinusoidal form from the network, and the use of inductors instead of current-limiting-dosing capacitors increases the reliability of the device.

Information sources

1. Device for charging a storage capacitor. Dodotchenko V.V., Nikolaev A.G., Bystrov V.K .; RU No. 2071167 C1, 6 H 03 K 3/53 1996.

2. The method of charging a capacitive electric energy storage device and a device for its implementation (options). Nikolaev A.G., Bystrov V.K .; RU No. 2218654 C2, N 02 M 7/162, 2003.

Claims (1)

A device for charging a storage capacitor, comprising a three-phase power source, the outputs of which are connected to one terminal of three current-limiting metering elements, the other terminals of which are connected to the inputs of a three-phase bridge converter, the outputs of which are connected to a storage capacitor, a control unit whose outputs are connected to the control inputs of a three-phase bridge converter, characterized in that the current-limiting-metering elements are made in the form of inductors, bridge the converter is made in the form of an autonomous voltage inverter with lockable keys, the inputs of the three-phase power supply are additionally connected to the inputs of the three-phase network voltage sensor, the outputs of which are connected to one input of the control unit, the inputs of the three-phase bridge converter are additionally connected to the inputs of the phase current sensors, the outputs of which are connected to other inputs of the control unit, the voltage sensor of the capacitive storage device is connected to the output of the three-phase bridge converter, the output of which is Inonii to another input of the control unit, to the other input of the control unit connected to the output voltage reference value storage unit back to one input of a control unit connected to the output drive charging rate setting unit.

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