DE1763553A1 - Method and device for controlling the charging of accumulators - Google Patents

Description

Patent attorney

Dr. Ing.Äckmann 22,813 (32,599 <äJi »! Mtfiu 2ο June 1968

Yardney International Corporation, New York N.Y. I00I3 (U.S.A.), 40-52 Leonard Street

Method and device for controlling the charging of accumulators

The invention relates to a control of the charging of accumulators and has as its subject a particularly expedient method and a device suitable for this purpose, by means of which gas formation is essentially prevented. The automatic control of the charge quantity for accumulators should be especially suitable for negative, ie negative pressures of the cells »

Most accumulators, especially those used in space flight, are sealed to protect the components and to maintain a long service life. However, a good sealing is difficult so that it is necessary to either a gas formation asu prevent or gas to remove that arises when overloading or relating to the store. The use of an auxiliary fuel electrode is known for this, which is caused by the action of the existing

-4 substances form a current that reduces the charging current

<° ornamental or disabling heating controls. This common nickel-cadmium accumulators method uses the resulting in the final phase of the charging process, ie at almost fully charged battery Säuer st off development of "Here, however, the state of charge

only detected in the positive pressure range, and the formation of relatively high cell pressures, e.g. up to 4 atm., towards the environment cannot be avoided. That is why the use of pressure-resistant thick-walled Metal housings necessary and a relatively high weight of the battery to be accepted. aside from that it takes a long time for the auxiliary electrodes to be positive Pressure range have completely consumed the oxygen produced during loading. When loading in series skins according to this well-known overcharge shutdown method Cell imbalances arise as a result of the deviations between the individual accumulator cells. As a result, the battery is switched off before all cells are really fully charged.

In contrast, it has been found according to the invention that for high charge values, for example 4 to 5 ampere hours, the best results are obtained when the battery is switched off after charging to about 70 to 80 fi of a full charge and then at a constant voltage at intervals of between 5 to 15 minutes will continue to be charged. For this interruption of the constant charging voltage, it is necessary to detect a lower state of charge at which the charging process should start again and to record an upper state of charge for switching off. The best method for controlling such a periodic charge is, according to the invention, to record the upper and lower current values for gas consumption, at which only kit ine gauges are developed before switching off, so that gauges can be consumed very quickly.

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However, this mode of operation is not possible in the case of excess pressures with respect to the environment, which according to the known Overpressure method in the above-described nickel-cadmium cells are characteristic. This is true especially to silver-cadmium cells, in which the gas pressure should not rise above about 0.7 kg / cm, because for weight reasons only light plastic housings should be used.

In contrast, the invention is based on the object of developing a method for controlling the discharge of accumulators, which automatically shows upper and lower charging ratios, the mode of operation being carried out with negative pressure in the cells. In addition, a charging equilibrium is to be maintained between the cells of an accumulator. To prevent gas pressures during charging in order to avoid the use of the otherwise required pressure-proof heavy metal housing.

This object is achieved according to the invention in that the gas pressure of each individual accumulator cell is determined, the charging current is determined by a switching device Reaching a predetermined upper gas pressure value in one of these cells is interrupted and after it has fallen a predetermined lower gas pressure is switched on again and the current interruption and reconnection so is repeated for a long time until the accumulator has a desired Has reached the charge level.

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Pur the control process is useful in each cell an auxiliary electrode is provided, wherein the auxiliary electrode circuit of each cell when a predetermined upper current value is reached, the charging current via a Switching device interrupts and switches on again when a predetermined lower current value is reached.

Further features of the invention relate to one for the Implementation of the method suitable loading / device and are mentioned in the subclaims and the following description · The description is based on multiple drawings:

Figure 1 shows a graphic representation of the charging results of an Ag-Od cell with the known charging method,

Figure 2 shows a graph of the charging results for an Ag-Cd cell with the mode of operation according to the present invention, and

Figure 3 shows partly schematically, partly as a block diagram the preferred embodiment of a charging device according to the present invention.

FIG. 1 shows the charging processes according to the known method of bit overpressure and positive auxiliary electrodes for controlling the charging of silver-cadmium accumulator micelles. It can be seen that when cells are charged, the gas pressure and the recombination or consumption current 9M mn remain relatively constant for about 15 minutes until the upper charge cut-off value is reached, 109821/0649

SAD

whereupon the gas pressure is relatively strong to about I, o5 kg /

2
cm and the grass consumption flow all of a sudden to its cut-off value of e.g. Io ο Q (A. rises. However, if the cut-off value is reached, the gas consumption current in the auxiliary electrode circuit remains essentially constant compared to the gradually falling cell pressure. Therefore, this control method also includes In addition, when charging cells connected in series according to the known method, where one of the cells is used as a control cell to switch off the charging current, charge imbalances are caused by the differences between the individual battery cells arise.

Figure 2 shows the charging result of silver-cadmium cells with the same structure as those used in Figure 1 , but according to the charging method according to the invention. As Figure 2 shows, originated during the charging of Accumulators to a constant Spannungeniveau of about 1.6 volts tin lighter gas increase, accompanied by a Gaeverzthr current which remained vernachläasigbar small for a period of about 15 minutes, after stitg dtr Gaavtrzthr- current of the auxiliary electrode steeply dtn Stromwtrt of loo ITA "ta, in which Sparks of Ladtetrom from Akkusulator with Helps tintr w / pus unttn nähtr bttohritbtntn Sohalt vorriohtung abgttohalttt wurdUt /

1 09821 / 06AS

After switching off, there was a slight increase in the cell pressure and the gas consumption fell to a current value of 5ο WJU, at which the constant charge voltage was reconnected to the accumulator. The gas consumption flow then increased again in the same way as in the first period up to the upper cut-off value of 100 IBiA. at where it reached the switch-off value again. After the charging current was switched off, the gas consumption current fell again to its lower cut-off value of 50 & La. and interrupted the effect of the constant charging voltage · In this way, periodic high current rates of, for example, 4 to 5 ampere-hours were obtained with their corresponding advantages. In the experiments shown in Figures 1 and 2, a silver-cadmium accumulator was used, which was provided with a kit of a platinum electrode. Measurement tests with electrodes which had between 2.5 and 8.5 mg platinum / cm ^{2 showed that a mini one of 5 mg platinum / cm 2 is} necessary if the auxiliary electrode is to be used for bridges over about 5 to 10 PSX. It is to be assumed that larger amounts appear necessary for an extended application because impairments are to be feared within the cell wrapping.

FIG. 3 shows the preferred embodiment of a loading tray neutral device according to the present invention, the specific L * d · characteristics of which have been examined in more detail with reference to FIG. Bti diesta performance absispi ·! consists dtr to be charged · Accumulator Io from a positive one 3 silver lead electrode 12, a negative cadaiue lead electrode

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14 and a platinum auxiliary electrode 16. The potential is "c7 any oxygen-consuming platinum electrode 16 to the cadmium electrode 14 lowered by a resistor in order to obtain a preselected ohmic load, which in the execution example was 5 ohms. It should be mentioned that in the example according to FIG 1 a lo-ohmic cut-off resistor 18 was used, to get higher cell pressures * The cut-off resistance 18 is in series with the primary windings 2o and two saturable iron core transformers 24 -

and 26 switched · You saturable core transformers 24 and 26 are used to saturate the current values of 5 ο IfA. and loo MA. or for the formation of switching currents in their respective switching lines 28 and 3o, which to the binary-logic current generator 32 lead. The secondary windings 34 and 36 of transformers 24 and 26 are Via diodes 38 and 4o with the switching lines 28 and as well as resistors 44 and 46 with the yoke terminal 42 connected.

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The transformers 24 and 26 work so that in the alternating current secondary winding 36 only produces a switching current when the direct current winding 40 «in Current of at least 50 mA flows, while for a Sohaltitrom in the alternating current secondary winding 34 in The equal troubles of 50 have a current of at least ten mA flow nut. Of course, this switching arrangement for loading a single or a row

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Use cells lo »loa etc., in that the line connecting the auxiliary electrodes and negative electrodes of each cell to be charged is connected to a switch 25, which corresponds to the structure mentioned above. 28a and 3o, 3oa of mediators 25, 25a are connected to an OE-logic current generator 32, which expediently consists of a bistable flip-flop holding device, to whose OR circuit the switching lines 28, 28a and 3o, 3oa are connected and their output terminals are connected to the base of the corresponding cut-off transistor. In the embodiment according to FIG. 3, the control switch 52 consists of a grid-controlled rectifier, via which the charger 54 is connected to the cells to be charged. The output line 6o of the logic current generator, which sends a control current to the control switch 52 in order to switch off the charger 64 Ton of the cell Io, is connected to the grid $ 8 and controls the rectifier 56. The output line 62 of the logic current generator is for a voltage reversal with the anode 64 connected so that the voltage is optionally fed back to the controlled rectifier 56 and the charger is switched off.

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When charging begins, the “bistable KLip-Hop circuit of the logic current generator 62 is in the switch-on position. If the gas consumption current in any cell rises to 50 mA, the transformer 26 sends a control current to the flip-flop circuit of the current generator 32. Since the KLip-flop circuit is already switched on at this point in time, it remains in the same switch position.However, if the gas consumption current of the auxiliary electrodes rises to 100 mA, the transformer 24 sends a control current to the KLip-Plop circuit, which results in a switch-off control current on the output line 62 through which the controlled rectifier · are is stromundurchlässig lower the ^C gas consumption currents of all the auxiliary electrodes under 5o mA ^ are the transformer 26 has a Ans ehalt current through the line to the logical flow encoder 32 which thereby via the output line 6ο a power-control current to the grating 58 leads.

Of course, the intermediary 25 is not on that Use of saturated core transformers to display the lower and upper current values is limited. So can For example, a suitable scanning device can be used, which lit the logical current balance of the current generator 32 is used »

When the cells to be charged reach the charging switch-off size, that is to say, when the Gaeverzthrstrom carries loo , the logieoht 3trom «ebir 32 in the

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Transit line 62 a control current for switching off, which suitably from a voltage reversal opposite the cathode 64, whereby the controlled rectifier 56 is non-conductive and the charging current of the Charger 54 is switched off by the cells lo, loa. After switching off, the flow of grass consumption in cells lo, loa will decrease, as described above in relation to FIG is written until it has fallen below 50 mA in all cells, whereupon the appropriate mediator 25 a logic current generator 32 triggers, which emits a renewed switch-on control current at the output line 6o, which acts on the grid electrode 58 in such a way that the controlled rectifier 56 becomes conductive and when the charger is switched on, a further charge begins.

In this following charging the gas consumption current of the individual cells wivd faster increase to pf loo mA and carried out a corresponding shutdown. Have reached the lower gas consumption current range of 5ο mA all cells, an additional charge will take place.

In this way, all charged cells will have their full charge level corresponding to a power consumption of 100 mA after a suitable number of charging cycles. An essential advantage of the present invention is that a charging equilibrium is achieved for cells which differ from one another. Auierde "throws every line"

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individually monitored and is therefore against an impermissible Pressure rise, which would destroy the cell housing, protected · This can cause slight Plastic housings are used, with the best possible Ratio of charged energy to total weight is obtained.

Although the invention is described with reference to a control device that works with auxiliary electrodes, it should be noted that the actual causal control triggering takes place from the pressure, so that of course suitable pressure gauges, such as strain gauges or the like. , which receive the pressure of each cell , predetermined upper and lower cell pressures.

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Claims (6)

Claims; 1. Procedure for controlling the charging of accumulators by interrupting the charging current "when reached a predetermined gas pressure, characterized in that that the gas pressure is determined in each individual accumulator cell, the charging current via a switching device Reaching a predetermined upper gas pressure value in one of these cells is interrupted and after it has fallen switched on again a predetermined lower gas pressure value and the current interruption and reconnection is repeated until the accumulator has reached a desired charge level. 2 · Method for controlling the charging of accumulators, characterized in that one in each cell Auxiliary electrode is provided and the auxiliary electrode circuit each cell, when a predetermined upper current value is reached, the charging current via a switching device interrupts and when reaching a predetermined the lower current value switches on again 3. Loading device for bureheading the procedure Claims 1 and 2, characterized in that each accumulator cell is provided with an auxiliary electrode and a switching device for switching a charging current on and off is provided, to which the auxiliary electrode circuits of each cell via current measuring devices act in such a way that the current measuring devices upon reaching a predetermined upper current value of each auxiliary 109821/0648 bad original electrode circuit a switch-off pulse and "at When a predetermined lower current value is reached, give a switch-on pulse to the switching device. 4. Loading device according to claim 3 »characterized in that that the switching device consists of a grid-controlled There is a rectifier, one main pole of which is connected to one pole of the accumulator and its other main pole to the charging current source connected. 5. Ladevorrichtung.mch claims 3 and 4, characterized in that the Einsehaltimpulse of the ammeter of the auxiliary electrode circuits on the grid electrode of the grid-controlled rectifier and the switch-off pulses to one of the grid-controlled rectifier main electrodes act. 6. Charging device according to claims 3 to 4, characterized in that as an ammeter for the auxiliary electrode control circuits two iron core transformers are provided with their primary windings in series are connected to the assigned auxiliary electrode and of which the secondary winding of the first transformer emits a holding pulse when it reaches a predetermined lower level Voltage value of the relevant auxiliary electrode circuit and that of the second transformer, a switching pulse when an upper voltage value is reached gives. 109821/0649