RU2543498C2 - Method of accumulator backup and device for method implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: during battery operation, only most discharged accumulators of the battery are recharged from individual voltage sources. Individual sources are made in the form of output cascades of DC voltage transducer and obtain power from backup accumulators of battery. Voltage equal to current mean voltage at the battery accumulators is formed at outputs of individual sources, and only electric power from main accumulators of the battery are used for load power supply.

EFFECT: increased number of charging/discharging cycles for battery including a sequence of main and backup accumulators, enhanced efficiency of backup accumulator energy utilisation.

2 cl, 1 dwg

Description

The present invention relates to the electrical industry and can be used in the operation of rechargeable batteries in autonomous power supply systems, in particular in power supply systems of artificial Earth satellites (AES).

When creating and operating satellite power supply systems, the problem of ensuring the necessary reliability of operation, which is determined primarily by the number of charge-discharge cycles provided by the system’s battery, is becoming increasingly important. To increase the number of charge-discharge cycles of rechargeable batteries, it is necessary to limit the depth of their discharge, which depends on many operational factors: the magnitude of the charge and discharge currents, the change in the load value, the degradation of the capacitive characteristics of the batteries, changes in the leakage currents of the batteries, and many other factors.

To increase the reliability of the functioning of power supply systems, satellites often use the increase in power of these systems through the installation of additional batteries. (See, for example, Spacecraft Power Systems. Novosibirsk, VO Nauka, 1994, Chapter 2. However, this inevitably leads to a sharp decrease in the specific energy characteristics of power systems. In some cases, especially in small spacecraft, this approach is not acceptable .. More appropriate seems to increase the duration of the battery life due to the backup of individual batteries in the battery.

The closest technical solution, which is selected as a prototype, is the "Method of supplying the load with direct current in an autonomous power supply system of an artificial Earth satellite" (RF Patent No. 2334337 C1, dated June 13, 2007). In this method, the improvement of the specific energy characteristics of the power supply system is provided by the inclusion of additional batteries in the battery. In this case, diode charging and discharge bypass circuits are connected to each battery of the battery, and the load is connected to all series-connected batteries through a step-down switching voltage regulator (in the work "RF Patent No. 2334337 C1, dated June 13, 2007" it is called a voltage converter 3) .

In the considered method of power supply in the process of discharging the batteries to the load, the energy of the additionally introduced batteries is used for current supply of all battery batteries by reducing the average value of their discharge current (by reducing the duration of the open state of the key devices of the pulse voltage regulator). Battery batteries, as a rule, have different quality charge-discharge current characteristics. The decrease in the discharge current of batteries having the best charge-discharge characteristics in the battery leads to the fact that for rechargeable batteries with a reduced current return, such recharge is insufficient both in magnitude and duration, which reduces the energy efficiency of the backup batteries, worsens the current charge -discharge characteristics of the entire battery, reduces the number of charge-discharge cycles provided by it.

The serial connection of the batteries in the battery leads to the fact that it has current charge-discharge characteristics of the battery with the worst load capacity in its composition. Therefore, in order to increase the number of charge-discharge cycles provided by the battery, it is necessary during operation to reduce the current load of the worst-performing batteries in the battery composition due to backup batteries.

The aim of the invention is to increase the number of charge-discharge cycles of a battery having in its composition series-connected primary and backup batteries, increasing the energy efficiency of backup batteries.

The goal is achieved by the fact that with the method of backup batteries of an autonomous power supply system containing a limited power source of electric energy and a battery of N main and K backup batteries connected in series with bypass charging and discharge circuits on each of them, which consists in conducting charge-discharge cycles and monitoring the voltage on the battery, only the most discharged batteries of the batteries are recharged from individual voltage sources Areas. Individual voltage sources are implemented on the basis of a common DC voltage converter. The value of the output voltages of individual sources during operation is maintained equal to the average value of the voltages on the battery batteries. Their output currents are limited by an acceptable value by means of limiting resistors and fuses. At the same time, the electric energy of the backup batteries is used to power individual sources, while only the main battery batteries are used to power the load.

In the battery backup device containing a battery with N main K backup batteries connected in series, with bypass charging and discharge circuits on each of them, and a voltage monitoring device connected to the output terminals of the battery, for this purpose, they are additionally introduced and connected by power circuits to backup batteries DC / DC converter with N + K individual output voltage sources, each of which is connected in series with union of a limiting resistor and fuse to one of a battery of accumulators. In this case, the load is connected to the main battery of the battery, and the value of the output voltages of individual sources due to the appropriate selection of the transformation coefficient of the transformer of the DC / DC converter is made equal to the average value of the voltage on the battery batteries.

According to the claimed method, the distribution of the electrical energy of the backup batteries between the batteries with the lowest load capacity during the operation of the battery is made by appropriate selection of the transformation ratio of the transformer of the DC / DC converter. Its value is chosen such that the output voltages of the individual voltage sources U _c are equal to the ratio:

$${\text{U}}_{\text{FROM}}={\text{U}}_{\mathrm{BUT}B}\text{/ (N}+\text{K), (1)}$$

where U _AB - voltage on the battery;

N is the number of main batteries in the battery;

K is the number of backup batteries in the battery.

Since the voltage on the battery U _AB is equal to the sum of the voltages U _{i of the} batteries included in its composition:

U _AB = Z _i U _i

where U _i is the voltage of the i-th battery;

then the output voltages of individual sources U _c in this case will be equal to the average value of voltages U _i on the battery:

$${\text{U}}_{\text{C}}={\text{(N}+\text{K)}}^{\text{-one}}{\Sigma }_{\text{i}}{\text{U}}_{\text{i}}\text{. (2)}$$

The drawing shows an electrical diagram of a device that implements the inventive method in the case when as a backup battery using one battery from the battery containing N + 1 batteries. The device includes: DC voltage converter 1 with power transformer Tr, output transistors T1, T2 and with individual voltage sources U1 ... U (N + 1); block of limiters 2 with fuses (for example, fuses) П1 ... П (N + 1) and limit resistors R1 ... R (N + 1); rechargeable battery 3 with diode bypass circuits, with one backup battery A1 and with the main batteries A2, ..., A (N + 1); voltage control device 4.

The midpoint of the primary winding of the transformer Tr of the DC / DC converter 1 is connected to the battery + bus + 3. The negative power supply bus of the DC / DC converter 1 (transistor collectors Tl, T2) is connected to the "-" backup battery A1 bus. DC / DC converter 1 contains "N + 1" individual voltage sources U1 ... U (N + 1), each of which is connected via fuse P and a terminating resistor R to one battery of battery 3. Battery A1 is backup, batteries A2 ... A (N + 1) - the main batteries of battery 3, to which the load is connected. Diode charging and discharge bypass circuits are connected to all battery batteries. The transformation coefficient of the transformer Tr is selected in such a way that the value of the output voltages of individual voltage sources U1 ... U (N + 1) is equal to the average value of the voltage Uc on the batteries of the battery 3. The voltage monitoring device 4 is connected to the output terminals of the battery 3. The output signal of the voltage monitoring device 4 are applied to the control input of the primary voltage source of the autonomous power supply system to limit the charge current. So, if a solar battery with a charging converter is used as the primary voltage source, the output signal of the voltage monitoring device 4 is fed to the control input of the charging converter. The diagram shows the terminal terminals of the battery 3 "+" 5 "-" and its charge current Iz supplied from the primary voltage source.

The device operates as follows. It is assumed that during operation of the battery 3 a limited power source (for example, a solar battery with a charging converter), from which the battery 3 is powered, provides a charge mode by limiting the amount of charge current Iz of the battery 3 and the voltage across it with acceptable values. In this case, the DC voltage converter 1 generates at the outputs of individual sources U1 ... U (N + 1) voltages U _c equal to the average value of the voltages on the battery batteries.

If the current value of the voltage U _i on the i-th battery due to its reduced load capacity is less than the output voltage of the individual source connected to it (U _i <U _c ), then the diodes of its rectifier open - voltage U _c is supplied to the i-th battery . Due to the electrical energy of the backup battery A1, partial or full compensation of the discharge current (load current) of the battery with reduced load capacity occurs and it is recharged to a voltage equal to the average voltage on the batteries of the battery 3. Moreover, the lower the voltage on the battery U _i , the the difference ΔU = U _c - U _i is greater and the larger current this battery is charged from an individual voltage source - from the backup battery A1. If the voltage on some battery of the battery turns out to be equal to the average value of the voltages on the battery of the battery (U _i > U _c ), then the rectifier diodes of its individual source are closed, voltage U _{c is} not supplied to this battery and it is not charged. Thus, only the lowest output voltage in the battery (with the worst charge-discharge characteristics) is recharged from the backup battery.

If in the process of recharging the main batteries, the voltage on the backup battery A1 drops and falls below the value of U _c , then the voltage at the output of individual sources U1 ... U (N + 1) also decreases. Their rectifier diodes are closed, thereby disconnecting individual sources from the main batteries. DC / DC Converter 1 starts to run in idle mode. The process of recharging the main batteries does not resume until the voltages on the main batteries of the battery decrease due to the load current and on some of them become lower than the voltage of the individual source.

If at the same time the batteries are charged at the same time with a charge current Iz, then its voltage at the output of the backup battery A1 can increase, while the voltage at the main batteries A2 ... A (N + 1) will increase much more slowly due to the load current . Therefore, the voltage U _c at the output of individual sources also begins to increase and becomes greater than the output voltage of one of the main batteries, the rectifier diodes of its individual source open - the charging mode of the main batteries resumes. Moreover, if Iz exceeds the current consumption of the DC-DC converter 1 in magnitude, then the voltage on A1 will continue to increase, increasing the output voltages of individual voltage sources U1 ... U (N + 1) and the number of individual sources with open rectifier diodes. As soon as the voltage on the battery 3 reaches the maximum permissible value, the voltage control device 4 generates a signal to reduce the charge current Iz or its complete cessation. Due to the load current, the voltage drop begins on the main batteries of the battery. In this case, the mode of recharging the main batteries continues due to the energy of the backup battery A1 until the voltage U _c becomes lower than the voltages of the main battery batteries.

Thus, in the automatic mode, the batteries are recharged while the output voltage of the individual voltage sources is stabilized at the level of U _c . In this case, the backup battery A1 gives off electric energy only to those main batteries that have the lowest output voltage and, therefore, have the worst current charge-discharge characteristics in the battery at the current time.

Bypass circuits due to the corresponding inclusion of diodes during normal battery operation are turned off and do not significantly affect the operation of the circuit. If the internal resistance of a battery of a battery suddenly increases, then a single bypass diode connected in parallel with the battery ensures that the discharge currents of the batteries pass to the load. Three sequentially connected bypass diodes (the number of diodes depends on the operating voltage of the battery) ensure the passage of battery charge currents and exclude the possibility of exceeding the maximum permissible value by the battery voltage. The limiting resistors R1 ... R (N + 1) set the values of the operating currents of individual sources U1 ... U (N + 1). If the internal resistance of the battery unexpectedly drops to a critical value (for example, a battery short circuit occurs), then fuse P accidentally disconnects the individual voltage source from it.

Thus, the claimed technical solution allows to increase the number of charge-discharge cycles of the battery, which has in its composition sequentially connected main and backup batteries, due to current recharge from backup batteries only those of its main batteries, the current charge-discharge characteristics of which are currently worse than the similar characteristics of other main battery batteries, and, therefore, ensures the achievement of the goal.

Information sources

1. Suetin B.P., Ivanchura V.I., Chernyshev A.I., Islyaev Sh.N. Spacecraft Power Systems, Novosibirsk: VO Nauka, 1994

2. RF patent No. 2334337 C1, H02J 7/35, dated 13.06.2007.

Claims (2)

1. The method of backup batteries of an autonomous power supply system containing a limited power source of electric energy and a battery of N main and K backup batteries in series with bypass charging and discharge circuits on each battery, which consists in conducting charge-discharge cycles and monitoring the voltage on the battery , characterized in that during operation of the battery its most discharged batteries are additionally recharged t of individual voltage sources, implemented on the basis of a common DC-voltage converter, the output voltage of the individual sources is maintained equal to the average voltage on the battery, their output currents are limited by resistors and fuses to an allowable value, while the backup electrical energy is used to supply individual sources accumulators, while only the main Battery kumulyatorov. 2. A battery backup device comprising a battery with N main K backup batteries connected in series, with bypass charging and discharge circuits on each of them, and a voltage monitoring device connected to the output terminals of the battery, characterized in that it is additionally introduced and a DC / DC converter with N + K is connected by power circuits to the battery backup batteries with individual voltage sources at the output, each of which is connected to Res series-connected limiting resistor and fuse to one of the battery of accumulators, wherein a load connected to the battery main battery and the output voltage of individual sources by appropriate selection of the coefficient of the DC voltage converter transformer is made the average of the voltages at the battery accumulators.