RU2749382C1 - Battery charger for capacitive energy storage device - Google Patents

Abstract

FIELD: chargers.SUBSTANCE: invention relates to chargers of capacitive energy storage devices, it can be used in high-voltage electric-physical installations of high power with a high level of stored energy. The charger of the capacitive energy storage device contains a DC voltage source, two metering capacitors connected in series, two diodes connected in series, two transistors connected in series, shunted by reverse diodes, a high-voltage transformer, and a high-voltage rectifier. A controlled key with two-way conductivity, a comparator, a source of a reference voltage, and a voltage sensor of the capacitive energy storage device are additionally introduced in the charger.EFFECT: increased reliability of the charger and expansion of its functionality.1 cl, 3 dwg

Description

The invention relates to chargers (ZU) of capacitive energy storage (CES) and can be used in high-voltage electrophysical installations of high power with a high level of accumulated energy.

Currently, in such installations, transistor-capacitor memory devices are widely used, built on the basis of high-frequency converters with a resonant nature of processes in the power circuits, which makes it possible to use the self-inductance of the matching high-voltage transformer as an active element of the resonant circuit. The metered method of transferring energy in such devices from the supply network to the CES makes it possible to quite simply regulate the charging speed and provide a parametric limitation of the current (output power) in the event of emergency modes in the output circuits.

Known transistor-capacitor chargers of increased frequency based on series resonant inverters, which can be made by bridge and half-bridge circuit [1 ... 3].

The disadvantage of such devices is that they are characterized by a significant uneven consumption of current and power from the network and, as a consequence, a low value of the utilization factor [2, 4] of the primary power supply k _and = P _av / P _max = 0.5, where P _max , P _cf - respectively, the maximum and average value of the active power consumed by the charger during the charging cycle of the CES. In high-power electrophysical installations with a high level of stored energy, this leads to an increase in the installed capacity of the primary power supply and its cost. In addition, with the commensurability of the maximum power of the charger P _max and the power of the primary power supply, such a nature of energy consumption in the mode of periodic repetition of charging cycles leads to voltage pulsations of the primary source (network), which reduces the reliability of other consumers [4].

A charger with dosing capacitors [2], selected as a prototype, is devoid of this drawback. The device contains a constant voltage source, to the output of which a charging converter is connected, containing two series-connected dosing capacitors connected to the positive and negative terminals of the constant voltage source, two series-connected diodes, the cathode of the first of which is connected to the positive terminal of the constant voltage source, and the anode of the second to the negative terminal of this source, and the common points of the metering capacitors and the common points of the diodes are connected to each other, two series-connected transistors, shunted by reverse diodes, the collector of the first of which is connected to the positive terminal of the power supply, and the emitter of the second to the negative terminal of this source, a high-voltage transformer , one terminal of the primary winding of which is connected to the common point of the transistors, and the second to the common point of the diodes, a high-voltage rectifier, the input of which is connected to the terminals of the secondary winding of the transformer , and the output is connected to a capacitive energy storage, a control device that generates control pulses supplied to the control circuit of the transistors.

With periodic locking / unlocking of transistors, the charging and discharging of the metering capacitors occurs and the dosed energy transfer from the DC voltage source to the CES with a constant dose value determined by the formula:

where C is the capacity of the metering capacitor; U _S is the voltage of the power supply.

At a constant repetition rate of transistor control pulses, the power transmitted to the CES is constant and is determined by the formula (2):

where η is the efficiency of the charger; Р ₁ - power consumed by the charger from the power supply.

The power values P _max and P ₁ remain unchanged in time until the voltage of the CES reduced to the primary winding of the transformer reaches a value equal to U _S / 2.

As a result, practically throughout the entire charging cycle of the CES, with the exception of the relatively short initial stage in comparison with the cycle duration [2], the charger operates in the mode of constant power consumption, while the utilization factor of the constant voltage source has the values k _and = 0.8 ... 0.95.

The disadvantage of the known device is that at the initial stage of charging until the voltage of the CES has not reached the boundary value U _gr , the switching of the memory transistors occurs at a non-zero value of the current flowing through them [2], and is accompanied by significant switching losses. The value of U _{gr is} determined from the relation (3) given in [2]

- соответственно, относительная и абсолютная длительность периода переключения транзисторов ЗУ;

- относительное значение граничного напряжения ЕНЭ, приведенное к первичной обмотке высоковольтного трансформатора; Q - добротность резонансного контура ЗУ.Where

- respectively, the relative and absolute duration of the switching period of the memory transistors;

- the relative value of the boundary voltage of the CES, reduced to the primary winding of the high-voltage transformer; Q - Q-factor of the resonant circuit of the memory.

Switching the memory transistors at a non-zero value of the current flowing through them leads to a sharp and significant increase in the temperature of the crystal of the transistors during the initial stage of charging [2]. This reduces the efficiency and reliability of the known device. In addition, switching processes lead to the induction of interference in the control and information networks of both the charger and electrophysical installations, especially with a large number of simultaneously operating memory devices as part of powerful electrophysical installations with a high level of energy accumulated in the CES, which causes malfunctions in their operation. and distortion of information obtained in the course of a physical experiment. This reduces the reliability of operation and can lead to emergency modes of the memory and electrophysical installations as a whole, as well as to the need to repeat physical experiments, which increases the cost of carrying out them, which, in turn, narrows the functionality of the known device and its area of application.

The proposed invention solves the problem of increasing the reliability of the charger of the capacitive energy storage and expanding its functionality, which is achieved by reducing the temperature of the crystal of the transistors during the initial stage of charging the CES and increasing the level of electromagnetic compatibility of the charger at this stage.

The specified technical result is achieved due to the fact that the charger of the capacitive energy storage contains a constant voltage source, two series-connected dosing capacitors connected to the positive and negative terminals of the constant voltage source, two series-connected diodes, the cathode of the first of which is connected to the positive terminal of the constant voltage source voltage, and the anode of the second to the negative terminal of this source, two series-connected transistors, shunted by reverse diodes, the collector of the first of which is connected to the positive terminal of the constant voltage source, and the emitter of the second to the negative terminal of this source, a high-voltage transformer, one terminal of the primary winding of which is connected to the common point of the transistors, and the second to the common point of the capacitors, a high-voltage rectifier, the input of which is connected to the terminals of the secondary winding of the transformer, and the output is connected to the capacitive one energy storage device, a control device that generates control pulses supplied to the control circuit of transistors. The novelty is that a controllable switch with double-sided conductivity is introduced, connected between the common point of the metering capacitors and the common point of the diodes, the control circuit of which is connected to the output of the comparator, to the first input of which a reference voltage source is connected, and to the second input of the voltage sensor, the input of which is connected to the terminals of the capacitive energy storage.

The introduction of these elements ensures the connection of a chain of series-connected diodes in parallel with the metering capacitors, starting from the moment the voltage of the CES reaches the boundary value. Up to this point in time, the power circuit of the memory device is a series resonant inverter, in which, when the condition T * ≥2 is fulfilled, the transistors are switched at a zero value of the current flowing through them, and the switching losses in them are equal to zero. After this moment, the power circuit is a memory with metering capacitors, in which, when the CES voltage is greater than the boundary switching of the memory transistors, it also occurs at a zero value of the current flowing through them, which excludes switching losses in them. This makes it possible to exclude a significant increase in the temperature of the crystal of transistors during the initial stage of charging, to increase the efficiency, reliability of the charger and the level of its electromagnetic compatibility.

FIG. 1 shows the electrical diagram of the CES memory.

FIG. 2 shows the timing diagrams of the CES memory obtained on the simulation model of the proposed device.

FIG. 3 shows the timing diagrams of the CES memory on an enlarged time scale near the moment of the key closure.

The developed charger of the capacitive energy storage (Fig. 1) contains a constant voltage source 1, to the output of which are connected two series-connected metering capacitors 2 and 3, as well as two series-connected diodes 4 and 5, the cathode of the first of which is connected to the positive terminal of the constant source voltage 1, and the anode of the second - to the negative terminal of this source 1. To the constant voltage source 1 are also connected two series-connected transistors 6 and 7, shunted by reverse diodes 8 and 9. The collector of the transistor 6 is connected to the positive terminal of the constant voltage source 1, and the emitter transistor 7 - to the negative terminal of this source 1. The device also contains a high-voltage transformer 10, the terminals of the primary winding of which are connected to the common point of the transistors 6, 7 and to the common point of the metering capacitors 2, 3. The input of the high-voltage rectifier is connected to the terminals of the secondary winding of the transformer 10 I 11, the output of which is connected to a capacitive energy storage 12. The control device 13, which generates control pulses, is connected to the control circuits of transistors 6, 7. The common point of the dosing capacitors 2, 3 and the common point of the diodes 4, 5 are connected by a controlled key 14, which has a two-way conductivity. This switch 14 can be implemented, for example, on the basis of a triac or two series oppositely connected transistors with reverse diodes [3]. The control signal of the switch 14 is the output signal of the comparator 15, to the first input of which the source of the reference voltage 16 is connected, and to the second - the output of the voltage sensor 17. The input of the voltage sensor 17 is connected to the terminals of the capacitive energy storage 12.

FIG. 2 shows the timing diagrams of the CES memory obtained on the simulation model of the proposed device with the parameters taken as an example: DC voltage source voltage 1 - 500 V; the capacity of the dosing capacitors 2, 3 - C _K = 0.5 μF; the leakage inductance of the windings of the high-voltage transformer 10, which performs the function of an element of the resonant circuit, - L = 6.5 μH; transformation ratio k ₂₁ = 1; energy storage capacity 12 - C _f = 10 mF; pulse repetition period of control of transistors 6, 7 - Τ = 33 μs; the value of the boundary voltage U _gr - 100 V.

FIG. 3 shows the timing diagrams of the CES memory on an enlarged time scale near the moment of closure of the controlled key 14.

In the diagrams in FIG. 2 and FIG. 3 letters indicate: a - the current curve of the primary winding of the transformer 10; b - curve averaged over a period период current consumed from a constant voltage source 1; в - the curve of the reduced voltage of the capacitive energy storage 12.

The principle of operation of the proposed device is illustrated by the diagrams shown in Fig. 2, 3, and is as follows.

At the initial stage of charging the capacitive energy storage 12, while the voltage at its terminals is relatively low, the output voltage of the voltage sensor 17 is less than the setting voltage of the source 16. In this case, the output signal of the comparator 15 is zero and the controlled switch 14 does not conduct (open). In this case, the power circuit of the memory has the configuration of a sequential half-bridge resonant inverter, which, under the condition of T * ≥2, operates in the mode of constant charging current of the capacitive storage 12 and current-free switching of transistors 6, 7 [2]. In this mode, the average value of the current consumed from the constant voltage source 1 increases linearly [1, 2].

When the voltage of the capacitive energy storage 12 exceeds the boundary value U _gr , determined by the formula (3), the voltage of the sensor 17 becomes greater than the reference voltage of the source 16, a high level signal appears at the output of the comparator 15, and the controlled switch 14 is turned on (closed). In this case, the power circuit adopts the configuration of the memory with metering capacitors [1,2]. Since the voltage U _{CES of the} capacitive energy storage 12 at the same time satisfies the condition U _CES > U _GR , the charger operates in the mode of currentless switching of transistors 6, 7 at a constant charging power and the average value of the current consumed from the constant voltage source 1 to the maximum, reduced to the primary winding of the high-voltage transformer 10, the voltage value of the CES equal to U _S.

As a result, in the proposed device, during the entire charging cycle of the capacitive energy storage 12, the transistors 6 and 7 are switched at zero current, and there are no switching losses in them. This, as shown in [2], allows more than 4 times to reduce the maximum temperature increment of the crystal of transistors at the initial stage of charging, which increases the efficiency and reliability of the proposed device. In addition, the elimination of switching processes in transistors and associated electromagnetic interference increases the level of electromagnetic compatibility of the charger.

From the timing diagrams (Figs. 2, 3) it follows that at the initial stage of charging the current averaged over the period Τ consumed from the constant voltage source 1 (curve b) and, therefore, the power consumed by the charger, linearly increase. When the voltage of the capacitive energy storage 12 reaches the boundary voltage value U _gr = 100 V (curve c), the controlled key 14 is unlocked and the memory goes into the mode of constancy of the consumed current and power transmitted to the capacitive energy storage 12.

From the current diagram of the primary winding of the transformer 10 (curve a) in FIG. 3, it can be seen that before and after the moment of unlocking the controlled key 14, the switching on and off of the transistors 6, 7 occurs during the interval of the current-free pause in the power circuit, which excludes switching losses in them.

As shown in FIG. 2 diagrams of current consumption (curve b), the duration of the initial stage of charging the capacitive energy storage 12 is 0.32 T _c , where T _c is the duration of the charging cycle. According to this diagram, the utilization factor of the constant voltage source will be

Thus, the value of the utilization factor of the constant voltage source when using the proposed charger lies within the limits corresponding to the prototype.

From the above description it follows that the use of the proposed device eliminates switching processes and a significant increase in the temperature of the crystal of transistors at the initial stage of charging the capacitive energy storage, which increases its efficiency, reliability of operation and the level of electromagnetic compatibility.

All this allows, as a result, to use the proposed device in powerful high-voltage electrophysical installations containing a significant number of parallel operating memory, with the energy level accumulated in the CES, up to hundreds of MJ, which significantly expands its functionality.

Information sources

1. Semiconductor chargers for capacitive energy storage devices / O.G. Bulatov, B.C. Ivanov, D.I. Panfilov - M .: Radio and communication, 1986 - 160 p. (p. 43).

2. Kopelovich E.A., Khvatov S.V., Vanyaev V.V., Troitsky M.M., Flat F.A. Transistor-capacitor chargers for megajoule capacitive energy storage devices. Electrical engineering, No. 7, 2010 - p. 11-16.

3. Power electronics: textbook for universities / Yu.K. Rozanov, M.V. Ryabchitsky, A.A. Kvasnyuk. - M .: Publishing house. House of MEI, 2007 - 632 p. (p. 466, p. 384).

4. Knysh V.A. Semiconductor converters in storage capacitor charging systems - Leningrad: Energoatomizdat, 1981 - 160 p.

Claims (1)

A capacitive energy storage charger containing a constant voltage source, two series-connected metering capacitors connected to the positive and negative terminals of the constant voltage source, two series-connected diodes, the cathode of the first of which is connected to the positive terminal of the constant voltage source, and the anode of the second to the negative terminal of this source, two series-connected transistors, shunted by reverse diodes, the collector of the first of which is connected to the positive terminal of the constant voltage source, and the emitter of the second to the negative terminal of this source, a high-voltage transformer, one terminal of the primary winding of which is connected to the common point of the transistors, and the second - to the common point of the metering capacitors, a high-voltage rectifier, the input of which is connected to the terminals of the secondary winding of the transformer, and the output is connected to a capacitive energy storage, a control device, f forming control pulses supplied in the control circuit of transistors, characterized in that a controllable key with double-sided conductivity is introduced into the device, connected between the common point of the metering capacitors and the common point of the diodes, the control circuit of which is connected to the output of the comparator, to the first input of which the source of the reference voltage is connected , and to the second - the output of the voltage sensor, the input of which is connected to the terminals of the capacitive energy storage.

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