DE1590863A1 - Automatic power supply system for direct current consumers - Google Patents

Description

Registration number. DP 11 a -ITraiikfur-VMain, August 25, 1969

VARTA AKTIENGESELLSCHAFT

6 Frankfurt / Main, Neue Mainzer 'Strasse 5

Automatic power supply system for direct current consumers

The invention relates to an automatic power supply system for direct current consumers with a direct voltage source, which in normal operation the consumer is supplied with nominal voltage and at the same time a buffering and emergency supply charges the battery divided into two groups, whereby the battery groups are each parallel to the source of direct voltage and each A variable series resistor is assigned to each battery group, and with a switching device, which in the event of failure of the DC voltage source or larger voltage drops, the two battery groups are connected in series, with the series voltage of both battery groups also corresponds approximately to the nominal voltage.

Reliable energy sources are required for switching and monitoring devices in power supply systems. Man therefore often feeds these systems with direct current in conjunction with a battery. This mode of operation is generally referred to as buffer operation. In such systems, a mains-powered charger, e.g. a rectifier, and the battery are in Parallel connection connected to the consumer. The battery smooths the ripple direct current supplied by the rectifier, absorbs peak loads and takes over the power supply in the event of a power failure.

The problem with these known systems is in particular

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for each documents (Art 7 § I Ab », 2 No. 1 Clause 3 de« Amendment ··, v. 4.9.

the difficulty of the prescribed voltage limits at the consumer to be observed. These voltage limits are due to the fact that the charging voltage of the battery is always higher than the nominal voltage, but this nominal voltage should also be adhered to in the event of a long-term disturbance in the network.

One is therefore forced to use the supply rectifier from the outset to regulate to the maximum permissible voltage value of the system and always connect the consumers to the to operate the highest voltage limit. In the event of a power failure and the associated discharging of the battery, the terminal voltage drops until it has reached a lowest permissible value. In many cases this is still above the permissible end-of-discharge voltage the battery.

The mean voltage level of the battery is in the flat part of the battery discharge curve, which occurs approximately between 20 % and 80 % of the capacity drain. Since the battery is operated from the continuous charge in the event of a power failure, the flat part of the discharge is usually already considerably below the Henn voltage. If the consumer is not to be operated with undervoltage in the course of the further discharge, the discharge must in many cases be interrupted before the battery final discharge voltage is reached. The full battery capacity can therefore not be used.

Voltage tolerances can only be reduced within certain limits by overdimensioning the battery takes place, whereby the lower limit voltage value? higher.

Another possibility is to divide the battery into a main group and an additional group of cells, the so-called Switch cells. The stem cells are always parallel to the consumer, the switching cells are only activated at a certain lower level Voltage limit of the power source switched on automatically. When the charge begins and the voltage rises, the switching cells

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switched off again. Kit with the help of a load resistance made sure that the ochalt cells are discharged evenly; However, this alone does not guarantee that it will affect everyone Time are in the same state as the stem cells.

An automatic power supply of this type, which contains two groups of batteries, which are connected in series in the event of a power failure v / ground is described in DAS 1 137 ^ 99. The one shown there However, circuit has significant disadvantages. Both battery groups are there with the same pole (+ pole) via resistors on the DC power supply. It is a disproportionately high effort to connect the batteries in series in the event of a power failure required at switches. The contactors used must therefore have a large number of contacts, i.e. the system will expensive and prone to failure.

From DAG 1 136 764- there is also a circuit arrangement for interruption Switching from mains operation to battery operation known, which contains an additional rectifier. Such an additional rectifier However, a second battery group could only replace if the battery is in trickle charge, i.e. with very low current is charged. As soon as other charging methods are used need to be »for example if the battery is stronger Is exposed to loads, the rectifier must be dimensioned much larger, i.e. it becomes much more expensive. Besides half or a large part of the capacity of the battery is lost, so that either the remaining battery part again he has to be elected or peak loads can can no longer be reliably absorbed.

The disadvantages of the known systems are therefore poor battery utilization, unnecessary energy consumption, and higher costs by overdimensioning or by additional cells and in the bad voltage level of these arrangements. For this purpose, quite complex switching devices and control devices, eg.

00982T / 0806 BATH ORIGINAL

B. to determine the switch-on time of the switching cells, necessary.

These disadvantages are avoided in the automatic power supply system according to the invention, which is characterized by is that the negative pole of the first battery group via a diode with the negative pole of the DC voltage source and the positive pole via an adjustable resistor with the positive pole of the DC voltage source, the positive pole of the second Battery group via a second diode with the positive pole of the DC voltage source and the negative pole of the second battery group is connected via a second adjustable resistor to the negative pole of the voltage source, and that the positive pole of the first battery group with the negative pole of the second battery group via an electronic switching device, which connects the battery groups in the event of a power failure or overload, is interconnected.

In Figure 1, a switching device for performing the new method is shown.

FIG. 2 contrasts the voltage characteristics of this arrangement to the characteristic of a known arrangement.

The idea of the invention is to be explained in more detail with reference to FIG.

The entire battery is divided into two groups 1 and 2, where the groups can be the same or different numbers of cells. Each group is charged from the same charger or from the mains rectifier 3 independently of each other, whereby the charging method is arbitrary, e.g. normal, trickle or trickle charging. The charging currents in battery groups 1 and 2 are determined by the series resistors 4 and 5 set, through the diodes 6 and 7 a Prevents the groups from discharging at rest. These reverse flow periods can be omitted if switches are used in the charging circuits of the battery groups.

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ORIGINAL

-9 - " ^{from left}

Group 1 is charged for example via resistor 4 and Diode 6, group 2 via resistor 5 and diode 7 · Both battery groups however, they are always in the same state of charge. The resistors 4 and 5 can by other components that allow current regulation to be replaced, for example by magnetically controlled components such as buckling chokes and like that. '.

In the event of a power failure, the two groups are connected in series and feed consumer 8. The series connection is established by the component labeled 9.

Since when charging the battery groups, the total voltage of the Groups is due to the consumer, the battery groups are dimensioned so that the charging voltage of a battery group is below the Nominal rectifier voltage or the consumer voltage. The independent charging of the two battery groups v / ird the total voltage at rest be equal to or greater than the nominal voltage, i.e. the flat part of the voltage characteristic of the battery, is shifted into the range of the selected nominal voltage and thus enables better utilization of its capacity.

These relationships are shown in FIG. It represents curve 1 shows the course of the voltage in a previously common system.

In the example, the nominal voltage at the consumer TLt should be «24 volts. The deviations + 10% or - 15 % (according to VDE 0108) are selected as the permissible upper voltage limit. This corresponds to an upper voltage value of U ^ »26.4 volts and a lower voltage ^{value of Up β} 20.4 volts. The continuous charging voltage of the battery to be used must not exceed 26.4 · volts, ie 18 cells are required for a continuous charging voltage of the individual cell of 1.4 to 1.5 volts. When loaded with nominal current, these 18 cells have an average voltage of 1.2 volts per cell. Between 20 % and 80 % of capacity are the 18 cell

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with a total voltage of 22.4 to 21.2 volts below the nominal voltage of 24 volts. In the course of the discharge the battery voltage drops to the lower voltage limit of 20.4 volts. The discharge must be ended at this point, although theoretically the discharge can be up to a voltage of 19 »8 Volts, i.e. up to the final discharge voltage of 1.1 volts per cell could be continued. The capacity of the battery is therefore not fully used.

Curve 2 shows the voltage profile in the method according to the invention. The nominal voltage should again be 24 volts. The same values as above are permissible as deviations. The rectifier and consumer are then set to the nominal voltage of 24 volts, ie the nominal voltage is always applied to the consumer during mains operation. For the battery, 20 cells are selected in the example, which are charged in two groups of 10 cells each with 1.4 volts per cell = 14 volts charging voltage. At the moment of switch-on (t = o), ie when the battery groups are connected in series, the consumer voltage Ujt + 10 % _t, which corresponds to an input voltage of 1.32 volts per cell at the consumer. When the average voltage level of the cells of approx. 1.2 volts per cell is reached, the total operating voltage is around 24.2 volts, ie at U _n + 1 % Process and the battery is accordingly better used.

In the cited example of the known circuit, 18 cells must be selected due to the specified voltage limits. According to With today's method, however, it is possible to choose the number of cells purely from the point of view of optimal battery utilization, i.e. instead of the 20 cells mentioned in the example, / also depending on the requirements regarding the load 19 to 21 cells can also be used. The higher the number of cells selected for a certain specified nominal voltage the lower the cost, capacity and volume of the battery.

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The switchover in the event of a power failure by the component 9 Ka, for example, by being attached between the switching points 10 and 11 Contact sets of a network relay or a contactor triggered or to do without mechanical components entirely, by an electronic switch. Because of the high switching speed of such electronic components achieve an almost uninterrupted switchover. For example a pnp transistor can be used, its emitter at point 10 and whose collector is at point 11, the base is connected to the input voltage via a resistor and a blocking diode placed so that "if the input voltage fails, the emitter-collector path of the transistor becomes conductive and connects the battery groups in series. The mains voltage can be used as the control voltage of the transistor or the output voltage of the rectifier can be used.

If the battery is to absorb peak loads, the component will 9 »e.g. a transistor via one in the consumer circuit connected further transistor stage controlled so that it is for Example switches through in the event of sudden increases in current. In this case, the power rectifier can be designed for low power as short-term high loads are absorbed by the battery.

The advantages of the method according to the invention are those over the whole Discharge area favorable voltage level at the consumer as well as the favorable capacity utilization of the battery by the free choice of the number of cells described above. The mean deviation between nominal voltage and battery voltage is essential less than with known buffer circuits. Furthermore there is no Overdimensioning of the battery is necessary and costly additional charging devices are not required. Due to the even charge and When the battery groups are discharged, all cells have the same service life.

- patent claims -

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Claims (2)

Registration number. DP 11 a. Preiikfurt / r.ain, August 25, 1969 Patent claims 1. Automatic power supply system for direct current pre-loads with a DC voltage source, which supplies the consumer with nominal voltage during normal operation and at the same time charges a battery that is used for buffering and emergency supply and is divided into two groups, whereby the battery groups each parallel to the DC voltage source_ and each battery group is assigned a variable series resistor is, and with a switching device, which in the event of failure of the DC voltage source or major voltage drops the two battery groups connected in series, the series voltage of both battery groups also about the Rated voltage corresponds, characterized in that the negative pole of the battery group (1) via a diode (6) with the negative pole of the DC voltage source (3) and the positive pole via an adjustable resistor (4) with the positive Pole of the DC voltage source (3), the positive pole of the battery group (2) via a diode (7) with the positive pole of the DC voltage source (3) and the negative pole of the battery group (2) via an adjustable '»ider stand (5) with the negative Pole of the voltage source (3) is connected, and that the positive pole of the battery group (1) with the negative pole of the Battery group (2) via an electronic switching device (9) ϊ which connects the battery groups in the event of a power failure or overload, is interconnected. 2. Automatic power supply system according to claim 1, characterized characterized in that the electronic switching device (9) is controlled by the input voltage. C0982 1/0806 , K ^ oiJri sentence 3 of the amendment. v. 4.9. Ift- \ he new documents BATH ORIGINAL Automatic power supply system according to Claim 1, characterized characterized in that the electronic switching device (9) has a circuit in the consumer circuit caused by the load controlled further switching device is controlled. BAD ORIGINAL 009821/0806