DE2051527A1 - Method and device for fast charging of electric batteries - Google Patents

Description

McCULLOCH CORPORATION, Los Angeles, State of California (V.St.A.)

Method and device for rapid charging of. electric batteries
Addition to the patent. ... ... (patent application P 16

38 085.1-32)

The main patent is a method for rapid charging of an electric battery by means of a high charging current, in which the charging process is interrupted for a short discharge at a high discharge current and finally terminated after a certain charge state has been reached, and an apparatus for carrying out this method.

The problem of ending the charging process at the right time is of particular importance in this fast charging process. The present further development is therefore based on the task of specifying ways and means with the help of which that point in time can be determined and made usable for ending the loading.

109818 / U6A

According to the invention, the state of charge determining the end of charging is activated by monitoring a the terminals of one or more cells of the battery detachable measurable variable determined. The monitored The measured variable can be the relaxation at a certain point in time after the start of discharge or the frequency of the Be discharge pulses during the fast charging process.

A device according to the invention for performing this Procedure is characterized by

a) first switching means, which when the Battery charging current in a nominal hourly capacity the cells above height,

b) a discharge current path,

c) second switching means 2um intermittent short-term Applying the discharge current path to the battery,

d) third switching means for determining the terminal voltage at a specific point in time after application of the discharge current path, and

e) fourth switching means, which on the third switching means address and the fast charging process Prevent further charging current supply in an excess of the nominal hourly capacity of the cells Stop altitude as soon as the third switching means detect a certain voltage (FIGS. 5, 6, 7).

The drawings illustrate embodiments of the invention in connection with the subject matter of Main patent. In the drawings shows

Fig. 1 is a block diagram showing a Arrangement for manual or automatic termination of the rapid charging process;

Fig. 2 is a Scheir.atisches, partly in block form Drawn diagram of an arrangement for the automatic termination of the rapid charging process depending on the average current during discharge;

109818 / U64

3 is a schematic, partly in block form Drawn diagram of an arrangement for the automatic termination of the rapid charging process as a function of the terminal voltage of the battery during discharging;

4 is a graph showing the terminal voltage of a battery during discharge at shows different charge states;

Figures 5 and 6

schematic diagrams, some of which are drawn in block form, of modified circuit arrangements according to that in Fig. 3;

Fig. 7 is a schematic diagram of a particular *

Application of the automatic termination %

Circuit in Fig. 6;

8 is a schematic diagram, partly in block form, of an arrangement for automatic termination of rapid charging of a battery depending on the during energy emitted by a discharge process; and

9 is a schematic diagram, partly drawn in block form, of an arrangement for automatic termination of the snow charging of a battery depending on the frequency of the Discharge intervals.

In Fig. 1, the circuit used to charge a battery 1 is shown. A charging current source 2 is with ä

the battery 1 via a control circuit 3 and a Main switch 4 connected. The voltage source 2 can Supply direct current or alternating current, the latter being rectified by the control circuit 3. Of the Main switch 4 can be either electrical or manual be operated switch. As in the main application P 085.1-32 and the additional application filed at the same time P .. ·. ..... (attorney's mark M 161)

is, the control circuit 3 repeatedly performs the following steps with respect to the battery:

109818 / U64

it supplies a charging current from the voltage source 2 to the battery 1; monitors the terminal voltage, temperature or pressure of the battery 1 during charging; and creates a discharge current path when the monitored parameter assumes a selected value. The circuit shown in Fig. 7 of the main application P. 16 38 085.1-32 could serve as control circuit 3 if the voltage source 2 supplies continuous DC voltage. If, however, the voltage source 2 supplies alternating voltage, then the circuit arrangement disclosed in the additional application filed at the same time (attorney's mark M 161) can be used as the control circuit 3. A battery voltage sensor 5 can be connected either in series with the battery 1 or in parallel to it with the aid of a switch. When the contacts 7 and 8 of the switch 6 are closed (see FIG. 1), the sensor 5 is parallel to the battery 1 and therefore monitors the terminal voltage of the battery. If, however, the contacts 9 and 10 of the switch 6 are closed, the sensor 5 is in series with the battery 1 and monitors its terminal current. The switch 6 is indicated in Fig. 1 in order to show the sensor 5 in general form. In any practical embodiment of the invention , the sensor 5 would ordinarily monitor only one terminal characteristic of the battery 1. The terminal characteristics of the battery 1 change and therefore represent the amount of charge supplied to the battery 1 as the rapid charging process progresses. A feedback element 11 from the sensor 5 to the main switch 4 and an indicator 12 are shown schematically in FIG. If the main switch 4 is a manual switch, the feedback element 11 is practically represented by a person who reads the value of the monitored terminal characteristic on the indicator 12 and opens the switch 4 by hand when the monitored terminal characteristic assumes a predetermined value and thus indicates, that the battery 1 has reached the desired state of charge .

10981 8 / U64

However, if the switch 4 is an electrical switch, the sensor 5 generates an actuation signal which about ■. as feedback member 11 electrically to Main switch 4 is returned and opens it. In this way, according to the invention, a terminal characteristic becomes of the battery 1 monitored by the sensor 5, and the fast charging process is through Opening the main switch 4 or in some other way, for example by switching on a high impedance interrupt the charging current path in order to reduce the charging current down to a buffer charge level, after the monitored terminal characteristic ™

assumes a predetermined value which indicates that the battery 1 is fully charged or at least has received a desired amount of charge.

FIG. 2 shows an arrangement which monitors a specific terminal characteristic of the battery 1, namely the average current per unit of time. An interrupter 20 is connected between the charging current source 2 and the control circuit 3. If the average current exceeds a predetermined value by a winding 21, the breaker 20 opens, thereby ending the rapid charge 'ä

Occurrence. In this embodiment of the invention, the contact 9 is closed, and the battery 1 is in series with winding 21 and a normally open contact Ap, which is the average discharge current sensor represents. Between the control circuit 3 and the battery 1 is via a normally closed contact A ^ an alternative Current path provided.

109B18 / H64

The contacts A ₁ and A_ are controlled by a relay winding which forms part of the control circuit 3. If the in Fiq. 7 of the main application P 16 38 085.1-32 is used, it is the winding W. which controls the contacts A and A ". The relay winding controlling contacts A. and A. is energized during each discharge interval and de-energized during each charge interval. In this way, the battery 1 is connected directly to the control circuit 3 via the contact A during each charging interval, while it is connected to _{the discharge current sensor through the contact A 2} and the winding 21 during each discharge interval. As stated above, the charging intervals last until the terminal voltage, the temperature or the pressure of the battery 1 reaches a selected value. Since the size of the charge in the battery increases in the course of the rapid charging process, the discharge pulses occur more frequently. Thus, the current flowing through the winding 21 increases in the unit of time, reaches a predetermined value corresponding to a selected state of charge of the battery 1, whereupon the interrupter 20 opens and ends the rapid charging process. 3 shows a circuit arrangement which automatically terminates the rapid charging process when the terminal voltage of the battery 1 assumes a predetermined value after a certain period of time after the start of the discharge current flow during a discharge current interval. The curves in FIG. 4 represent the terminal voltage of the battery 1 as a function of time after the discharge current path has been applied and thus during the discharge of the battery in the course of the charging process of the additional application filed at the same time (attorney's reference number H 161)

109818 / U64

as charging current source 2 and control circuit in Fig. are used, the terminal voltage falls from its value at time T. at a rate which depends on the state of charge of battery 1. Decreased with increasing charge in battery 1 the decrease speed. Therefore, the terminal voltage of the battery 1 increases after being discharged for a certain period of time up to the point in time T "with the size of the charge.

As Fig. 3 shows, the battery 1 is connected to the control circuit 3 via a contact 7, while a ηοχ-mally open contact A- and a relay- ^

winding W in series and via a contact 8 as well on the control circuit 3. Contact A " is controlled by the same relay in the control circuit as contact A. in the arrangement of Fig. 2. A zener diode 30 and a current limiting resistor 31 are in series in parallel with the battery via a normally open contact B. The winding 21, a silicon rectifier 23 and a current limiting resistor 24 are also located above the battery 1 through the contact 7.

The relay W_ is a delay relay. Hence will the closing of contact B after closing the "

Contact A_ delayed by the period T_ - T ^. the The connection point of the Zener diode 30 and the resistor 31 is with the control terminal of the silicon rectifier 23 connected. When the battery is being charged, the silicon rectifier 23 is non-conductive. Every time the contact A “closes during a discharge interval, it closes Contact B a short period of time thereafter (namely at time T_ in Fig. 4) by the terminal voltage

109818 / U64

of the battery 1 to the Zener diode 30 and the resistor 31 lying in series with it. When the battery 1 is fully charged or reaches the selected state of charge, then exceeds their terminal voltage applied to the Zener diode 30 and the resistor 31 when the contact B closes the breakdown voltage of the Zener diode 30, so that current flows through the resistor 31. if this is done to the control terminal of the silicon rectifier 23 a positive voltage is applied and ignites it. The then from the battery through the Winding 21 flowing current is sufficient to open the contact of the breaker 20 and the Schnelladevorcjanq to end. Furthermore, the relay contact A ″ opens with the interrupter 20 and prevents unnecessary discharge of the charged battery 1 #

FIG. B shows a modification of the switching arrangement in FIG. 3, has taken the place of the delay relay W_ a monostable multivibrator 32 at. The resistors 33 and 34 and the contact A ″ are above the battery 1. The trigger input of the multivibrator is coupled to the connection of the resistors 33 and 34, while the output of the multivibrator 32 is at the connection point of the Zener diode 30 with the resistor 31 . The connection of the winding 21 and the Zener diode 30 is connected to the junction of the contact A ~ and the resistor 33. When the contact A "closes at the beginning of each discharge interval, current flows from the battery 1 through the resistors 33 and 34, as a result of which the multivibrator 31 is triggered into its semi-stable state for the period T" \.

1 0 9 8 1 8 / U 6 4

BATH ORIGINAL

When the multivibrator is in this semi-stable State, there is a negative potential at its output. Because of this, the silicon rectifier 23 unable to ignite regardless of the terminal voltage of battery 1. After that period of time the multivibrator 32 returns to its stable state back: in which there is positive potential at its output terminal. If at this point in time Id.h. to the Time T ,. 4) the terminal voltage of the battery 1 is sufficiently high, the silicon rectifier ignites 23 and the contact of the interrupter opens, so that the rapid charging process is ended.

Flg. 6 shows a further modification of the switching arrangement in FIG. 3, in which the delay relay W _{ß is replaced by} a delay circuit 39. The delay circuit 39 lies across the load resistor 40, which is switched into the circuit across the battery 1 as a discharge current path when the relay contact A .. , which is in series with the resistor 40 across the battery 1, closes. The delay circuit 39 also includes a resistor 41 which is in series with the parallel arrangement of a capacitor 42 and a resistor 43. The voltage level sensor circuit of the Zener diode 30 and the resistor 31 are connected to the capacitor 42.

When the contact A ₂ closes at the beginning of each discharge interval, current flows from the battery 1 through the resistor 41 and the capacitor 42 begins to charge.

10981 8 /

At the end of each discharge pulse and when opening of contact A ^. the capacitor 42 overdischarges the resistor 43 in parallel with the series connection of the resistors 41 and -10. When the cargo of the Battery increases and the terminal voltage increases during the discharge processes, the capacitor becomes 42 charged to this higher voltage.

The voltage across capacitor 42 is across Zenerdioce 30 and resistor 31. When the If the capacitor voltage exceeds the Zener voltage of the diode 30, current will flow through the resistor 31 and the cathode port connection of the silicon rectifier 23, so that it ignites. Accordingly, current flows from the battery 1 through the winding 21 and opens the contact of the breaker 20, so that the rapid charging process is terminated. The delay circuit can also be omitted if the response time of the Voltage sensor circuit or the associated elements how the zener diode 30 is sufficiently long.

In some cases it is desirable to apply a trickle charge at the end of the quick charge pre-qanue. A circuit for this is shown in FIG. The charging current source 2 and the control circuit 3 according to FIG. 10 of the abovementioned simultaneous application (attorney's mark M 161) are used in connection with the battery voltage sensor of FIG. Instead of the winding 21, a relay winding W ″ is provided in order to control the termination of the rapid charging process. In addition, a silicon rectifier 30 is connected in series with a current limiting resistor 50 and a secondary winding 66 takes the place of the relay contact Ap and the load resistor 40 in FIG. 6 explained above. .

BAD ORIGINAL 109818 / U64

The mode of operation of the control circuit of the ί-'ig. 7 is described in detail in the aforementioned simultaneous patent application and is intended by reference then count as repeated here.

Do that scarf; is modified by the addition of a normally open relay contact C- between the de; r: gate and the cathode of rectifier 70. As soon as this contact closes, the rectifier 70 is prevented from providing a low-resistance current path for the passage of charging current by triggering. However, a low charging current flows through the current path of the diode 75 and the resistor 76 of higher resistance, so caß the battery 1 after completion of the Schneiladevorganges still a buffer charge is supplied. The closing of the relay contact C_ takes place as follows: When the controlled rectifier 80 is ignited, the terminal voltage of the battery 1 is applied to the terminal sensor in order to activate the controlled rectifier 23 depending on the reaching of a certain terminal voltage (to which a selected state of charge of the battery 1 belongs) to operate. Its ignition allows sufficient current to flow through the relay winding W_ to excite it, so that the contact C "closes. This simultaneously opens the contact C. and switches the secondary winding 66 out of the circuit, so that the controlled rectifiers 23 and 80 remain positively biased by the battery 1. In this way, the winding W also remains energized and keeps the relay contact C ″ closed for the supply of further buffer charge.

In Fig. 6, a switching arrangement is shown in the üer fast charging process as a function of the

BATH ORIGINAL

1 0 9 8 1 0/1 A 6 U

by the battery during a discharge interval delivered energy compared to the energy introduced during the adjacent charge interval terminates automatically. As the fast charge progresses, it decreases during the charging intervals Energy introduced into the battery 1, while that given off by the battery 1 during the discharge intervals Energy increases until the energy introduced and the energy released at successive Charging and discharging intervals is the same. When this equilibrium condition occurs, the battery is 1 fully loaded. According to FIG. 8, a resistor 90 is connected in series with the battery 1 and the contact 9. The voltage across resistor 90 is at the input of a bridge circuit 91. The branches of the bridge circuit are of diodes 92 and 93, their connection to one end of the resistor 9o, and the RC elements 94 and 9 5 formed, the connection of which is connected to the other end of the resistor 90. The end connections a potentiometer 96 are at the output of the bridge yi. In other words: the connection of the Diode 92 and the RC element -94 is with one end connection of the potentiometer 96, and the connection of the RC element 95 with the diode 93 is with the other End connection of the potentiometer 96 connected. The sliding tap of the potentiometer 96 is directly on the Control terminal of the rectifier 23. During the charging intervals, current flows through from the charging current source 2 the diode 93 and charges the RC element 95. During the discharge intervals Current flows from the battery 1 through the diode 92 and charges the RC element 94. Thus, the voltage at the RC element 95 of the energy introduced into the battery 1 during the charging intervals proportionally, while the voltage at the RC element 94 of the battery 1

1 Π 9 R 1 8/1 /, B A

energy released during the discharge intervals is proportional. If the voltage at the RC element 95 and the voltage at the RC element 94 are the same, the bridge circuit 91 is balanced. The tap of the potentiometer 96 is set so that it supplies a trigger voltage to the controlled rectifier 23 for this state, thereby opening the contact of the interrupter 20 and terminating the fast charging process. In some cases it may be desirable for time reasons to stop the rapid charge process before equilibrium is reached. Then the sliding tap of the potentiometer 96 μ is set so that the rectifier 23 ignites at a different ratio of the energy introduced to the energy output. The termination of the snow charging cycle on the basis of the energy delivery has the advantage over the termination based on other terminal characteristics that the same predetermined value, namely the equality of the delivered and the energy introduced, applies to all battery types. When the fast charging process ^ is terminated on the basis of other terminal characteristics, for example depending on the average discharge current, the terminal voltage at a certain point in time

after the start of discharge or the frequency of the discharge in %

intervals, the predetermined value, upon reaching which the process is ended, depends on the value to be loaded Battery type. Then it may be necessary to adjust the parameters of the switching arrangements, to adapt them to different batteries.

In Fig. 9, a circuit arrangement is shown which the fast charging process automatically depending on terminated by the frequency of the discharge intervals.

109818 / 1A6A

The charging current source 2 is connected to the control circuit 3 via an interrupter 20, whose Open contacts depending on the flow of current through a winding 21. The battery 1 is with the Control circuit 3 connected via a contact 9 and a frequency sensor 2 2, which a voltage generated by the battery 1 as a function of a selected frequency of the discharge current pulses. the Winding 21, a silicon-controlled rectifier 23 and a current limiting resistor 24 are located in Row above the battery 1. The silicon rectifier control terminal 23 is connected to the output of the frequency sensor 22. The control circuit 3 is also located directly to the battery 1, via a normally closed relay contact A. (see Fig. 2). Contact A is closed during the charging intervals and establishes a direct current path between the control circuit 3 and the battery 1, which the frequency sensor 22 bypasses. During the Entiadeintervalle the frequency sensor 22 sets the only current path between the control circuit 3 and the battery 1. When the battery 1 is charged, the controlled remains Rectifier 23 non-conductive. If the frequency of the discharge intervals reaches a predetermined value, which corresponds to a selected state of charge of the battery 1, the output of the frequency sensor 22 supplies a sufficient voltage to ignite the controlled rectifier 23. Accordingly, sufficient current flows from the Battery 1 through the winding 21 to open the contact of the breaker 20 and the rapid charging process to end.

10981 8 / U6A

Claims (8)

Expectations Method for rapid charging of an electric battery by means of a high charging current, in which After reaching a certain state of charge, the charging route for a short discharge interrupted at high discharge current and finally ended, according to patent. ... ... (patent application P 16 38 085.1), characterized in that the state of charge determining the end of charging is indicated by (| Monitoring of a measurable variable detected at the terminals of one or more cells of the battery which can be removed wire. 2. The method according to claim 1, characterized in that the monitored measured variable is the terminal voltage a certain point in time after the start of unloading. 3. The method according to claim 1, characterized in that the monitored measured variable is the frequency of the discharge pulses during the rapid charging process. 4. Apparatus for carrying out the method according to "Claim 2, characterized by a) first switching means that, when the battery is actuated, charge current in a nominal hourly capacity the cells above height, b) a discharge current path, c) second switching means for intermittent short-term application of the discharge current path to the battery, 1 Π 9 8 1 8/1 /, 6 A d) third switching means for determining the terminal voltage at a specific point in time after applying the discharge current path, and e) fourth switching means, which respond to the third switching means, and the rapid charging process by preventing further charging current supply in one of the nominal hourly capacity of the Exceeding cells terminate as soon as the third switching means has a certain voltage determine (Fig. 5, 6, 7). 5. The device according to claim 4, characterized by a delay network, which the application of the Terminal voltage delayed to the third switching means (Figures 3, 5, 6 and 7). 6. Apparatus according to claim 5, characterized in that the delay network contains a multivibrator, whose output signal occurs at a selected interval after the occurrence of the input signal, and that the fourth switching means contain a controllable switch, which by the multivibrator during the selected time interval is switched off (Fig. 5). 7. Apparatus according to claim 5, characterized in that the delay network RC elements with a predetermined Has time constant (Figs. 6 and 7). 8. Apparatus according to claim 4, characterized in that that the discharge current path is the coil of a delay relay and the third switching means is connected to the coil via a contact of the delay relay are (Fig. 3). 1 0 9 B j 0/1 /, 6 / ♦ Blank page