WO2003034567A1

WO2003034567A1 - Method and device for charging accumulators

Info

Publication number: WO2003034567A1
Application number: PCT/DE2002/003722
Authority: WO
Inventors: Ivo Huber; Michael Kranawetter; Georg Koch
Original assignee: Siemens Aktiengesellschaft
Priority date: 2001-10-10
Filing date: 2002-10-01
Publication date: 2003-04-24
Also published as: DE10149978A1

Abstract

The invention relates to a method for charging an accumulator which is coupled to a charge control device, using a charging device. The inventive method is characterised by the following steps: G) a charge current having a first current intensity (I1) is supplied over a pre-determined initialisation period (Δt1); H) charge current data is exchanged between the charge control device and the charging device during the initialisation period; and I) a charge current having a second current intensity (I2, I3) selected according to the charge current data is supplied. During the initialisation period, the charge current data are transmitted in a coded manner by means of pulsed transmission of the charge current having the first current intensity (I1). The invention also relates to a corresponding charging device.

Description

description

Method and device for charging accumulators

The present invention relates to a method for loading a coupled to a charge control device Akkumula ^¬ gate by means of a charging device and a corresponding ^¬ de loading device.

In various accumulators, such as for lead ^¬ or lithium-ion rechargeable batteries, it is necessary to charge the batteries with a current-limited voltage source, wherein the voltage very accurately controlled and possibly also changed even depending on the temperature of the battery cells ^¬ needs to be changed. If an empty battery is connected to the charging voltage source, the current limitation of this source prevents a charging current that is impermissibly high for the battery. The La ^¬ is despannung while initially lower than the maximum charging voltage. As the charge increases, the voltage rises to the set control voltage and is then limited by the voltage control that begins. Due to the increasing internal battery voltage (open circuit voltage) and the constant source voltage as well as the internal resistance of the battery, which is assumed to be constant in the first approximation, the current consumption of the battery decreases continuously from the point in time when the voltage limitation starts. This phenomenon is shown in the accompanying FIG. 3, the course of the charging voltage being represented by the curve denoted by U _La d _e and the course of the current consumption being represented by the curve denoted by I _ade . The point in time at which the voltage limitation begins is denoted by t ₀ . In the case of such a technique, the state of charge can be inferred from the amount of the charging current, and on the other hand the charging may have to be interrupted immediately or after a certain time if the charging current falls below a certain value. New generations of electronic devices for data applications, such as, for example, mobile radio terminals, require very high charging currents on account of the large range of functions, for example on account of the high data transmission rates (in particular in the case of video transmission, Internet transmission or the like). This is particularly necessary because the owner of such an electronic device should be able to recharge the accumulator arranged in the electronic device in the shortest possible time. On the other hand, it should be ensured that while the electronic device is being used in connection with a charger, the battery should not become empty, but should at least maintain its current state of charge despite use or even continue to charge the battery.

However, the provision of such high charging currents causes problems, especially at low temperatures and in the case of accumulators with small capacities. At low ambient temperatures (0 ° to 10 ° Celsius), the battery voltage may rise suddenly, especially when very high charging currents are applied. In the case of a lithium-ion battery, this increase in the battery voltage can trigger its protective circuit and thus lead to the device to be charged being switched off.

In order to solve this problem, the charging current source was realized as a current-limited, highly precise voltage source (linear or switching regulator), which was either placed very close to the accumulator or was connected to it via sense lines. This has the disadvantage that either the charging current source with its space requirement and its heat loss had to be accommodated close to the accumulator or that the sense lines increased the effort for cables and plug connections. To measure current, a shunt resistor has been pasted into the charging circuit and the sen gemes at this voltage drop ^¬. In turn, the shunt resistor has the disadvantage that it represents an additional voltage drop in the circuit, slows the loading process and thus represents a non unerhebli ^¬ chen effort for the measured values acquisition. This disadvantageous effect is present in particular when the shunt resistor is not arranged in the ground line - for example because of the ground coupling of the battery via the device to be operated - but is inserted in the plus line.

Furthermore, there is the problem that different types of batteries, for example NiCd / NiMH and Li-ion batteries, cannot be charged simultaneously with this principle because of the different charging end voltages. NiCd / NiMH batteries are charged with constant current regardless of the charging voltage.

From DE 195 20 041 AI it is known to use a special charger based on a regulated current source, the current value of which was regulated via the pulse-pause ratio of the current. With this concept, due to the variable current value, various accumulator technologies, for example NiMH accumulators or Li-ion accumulators, can be charged in the device without additional effort. However, this approach has the disadvantage that special precautions, in particular with clocked current sources, were required in the charging device in order to limit the occurrence of an overshoot of the current at the moment of switching on. This limitation was necessary because otherwise the temporary accumulator was subjected to a brief overvoltage when it was switched on, which could lead to its destruction.

From WO 00/42691 it is also known to use a power source connected to the electronic by three lines Terminal and thus connected to the accumulator. In this concept, the charging current is let without specifically ge ^¬ clocked charging current source set is needed here but a third control line and an additional scarf ^¬ trative expenditure of the loader, and on to ^¬ associated contact of the electronic device. Ren the width ^¬ it is necessary for this solution to make the total weight chen for tzli ^¬ contact at the charging socket of the electronic Endgerats additional protective measures against electrostatic discharge (ESD).

It is the object of the present invention to provide a method and a device for charging accumulators with which accumulators of various types can be charged reliably and quickly with relatively little technical effort.

This object is achieved on the one hand by a method for charging an accumulator coupled to a charging control device by means of a charging device, the method comprising the steps:

A) supplying a charging current with a first current strength over a predetermined initialization time period,

B) Exchange of charging current data between the charging control device and the charging device during the initialization time period and

C) supplying a charging current with a second current strength selected in accordance with the charging current data, the charging current data being transmitted coded during the initialization time period by pulsed transmission of the charging current with the first current strength.

In the method according to the invention, it is provided that a charging current with the first current level is first fed to the accumulator over the predetermined initialization time period, this initialization time period being used to charge the first current level with the first current level. Exchange destructive data that give the charger information about the battery to be charged. After the initialization time period, the second current strength of the La ^¬ least roms is then in accordance with the transferred charge current data is inserted ^¬, in an optimum manner for each accumulator to be charged. This means that in particular the level of the charging current and the course of the charging voltage in accordance with the transferred charge current data specific to the each ^¬ weils charged accumulator can be set.

With regard to the charging current data, it can be provided that this contains information which characterizes the state, in particular the state of charge, and the type of the accumulator to be charged in each case. The charging device can then use this information to determine the optimally suitable charging current and charging voltage profile, for example by reading from a table on the basis of the received charging current data, and can then charge the accumulator accordingly in accordance with this data. This makes it possible to achieve a greatly shortened effective charging depending on the accumulator to be charged in each case. The pulsed transmission of the charging current can be achieved in that the charging control device assigned to the rechargeable battery temporarily interrupts the charging circuit and thereby pulsates the charging current. The charging device can then transmit the charging current data on the basis of the interruptions or the pulsed charging current. It is conceivable for the charging current data to be digitally encoded as digital data in the context of a pulse train of the charging current and to be decoded by the charging device in order to determine the charging current.

In a development of the invention it can be provided that the charging device in step B) confirms the charging current data determined from the pulses by pulsed transmission of the charging current. This measure further increases the reliability of the method according to the invention. The charging control device then detects the sent confirmation and can terminate the charging process or initiate a new initialization if the charging device determines the charging current data incorrectly.

In order to prevent a charging current that is too high for the accumulator and can damage it during the initialization time period, an exemplary embodiment of the method according to the invention can further provide that the first current, preferably around the Half, is smaller than the second current. In particular, it can be provided that the first current is between 50mA and 200mA, preferably 100mA, and that the second current is between 500mA and 2A, preferably 1.5A. This measure ensures that during the initialization time period, during which the charging current data is also exchanged, a charging current with a sufficiently small first current strength is supplied to the accumulator, so that damage to the accumulator is excluded. During the initialization time period, it is all necessary to set the first current strength in such a way that the charging current data can be transmitted reliably and without interference in the form of pulse sequences or the like.

If, in individual cases, there is no exchange of the charging current data or an incorrect exchange of the charging current data, for example because the pulse sequences transmitted by the charging control device designate an accumulator to which the charging device does not have suitable charging current data, a further development of the invention can provide be that a predetermined second current is set by default. This second standard current can be, for example, around 700 mA. For this second standard current it is only necessary that it is sufficiently large to ensure at least partial charging of the battery in an acceptable time, but that it is not too large to _S chädigung exclude the non-defined by the charging device charged battery.

In the event that the charging process is interrupted, two options are possible: Short-term sub ^¬ interruption or a prolonged interruption of the charging ^¬ operation is completed. These two options are monitored using a second predetermined time period. If the charge ^¬ stream over the second time period or interrupted longer, the steps A to C are the procedural ^¬ invention Rens performed again, that is it finds again a Ini ^¬ tialisierung during the initialization time period instead of in which the charging current data to the rechargeable battery to be ^charged and determined. However, if the interruption in the charging of the accumulator is shorter than the second time period, step C is carried out with the second current intensity set last. In the second case, it is thus ensured that if the charging process is briefly interrupted, the initialization and determination of the charging current data need not be carried out again, as a result of which the charging process can be resumed despite the interruption without major loss of time.

The invention further relates to a device for charging a rechargeable battery coupled to a charging control device, in particular according to the method of the type described above, comprising: a changeable current source for providing a current with which the rechargeable battery is to be charged, a current control device for controlling the changeable current source and a Pulse detection device for evaluating charging current pulses, the pulse detection device monitoring the charging current for charging current data output by the charging control device in the form of charging current pulses, and the current control device following the current source for setting the charging current Controls the charging current pulses evaluated by the pulse detection device. This device can contact in herkömm ^¬ Licher manner with only two contacts, namely the mass ^¬ and the positive contact to be executed. To the delegation ^¬ supply the charging current information is strictly about the contacts so that no additional measures, in particular no measure ^¬ took to protect against electrostatic discharge (ESD) or the like made will have.

In a development of the device according to the invention it can be provided that the current control device is designed to operate the current source in a pulsed manner to confirm the charging current ^data with respect to the charging control device.

The invention further relates to a mobile electronic device, in particular a mobile radio terminal, comprising a charge control device and an accumulator for interacting with a device of the type described above, the charge control device having a switch for interrupting the charging current and a switch control device controlling the switch, the switch control device for Control of generation of charging current data in the form of charging current pulses in accordance with the state, in particular the state of charge, and the type of the accumulator.

The invention is explained below by way of example with reference to the accompanying figures. They represent:

FIG. 1 shows a simplified functional block diagram, comprising the charging device according to the invention, a rechargeable battery to be charged, and an interposed charging control device within an electronic device;

Figure 2 shows the course of the charging current over time in the inventive method; and Figure 3 shows the course of the charging voltage or current consumption in a method according to the prior art.

FIG. 1 shows a charging current source 10 ^{according to the} invention, which is coupled to an electronic device, for example a mobile radio terminal 12, for charging an accumulator 14 assigned to this device 12. In the following, the individual for realizing the invention Wesent ^¬ union components of loading device 10, electronic device 12 and accumulator 14 received, it being understood that other components in the respective devices 10, 12 and 14 may be included which are not mentioned in the description ,

The charging device 10 comprises a variable current source 16, which can be controlled via a current control device 18. Furthermore, the charging device 10 comprises a pulse detection device 20, which is coupled to the current control device 18 and the variable current source 16. M denotes the ground potential in all devices 10, 12 and 14.

The charge control device 12 comprises a switch 22 and a control unit 24 controlling it, for example in the form of a microcontroller. In addition, the charge control device 22 comprises an analog / digital converter 26.

The accumulator 14 comprises a capacitor 28 and an internal resistor 30.

The charging device 10 is detachably coupled via the ground contact 32 and the contact 34 to the electronic device 12, in particular to its charging control device. The electronic device 12 is detachably coupled to the accumulator 14 via the ground contact 36, the charging contact 38 and the initialization contact 40. To explain the function of dargestell ^¬ in Figure 1 th block diagram is discussed below in addition to FIG. 2

The charging process begins at time tO. At this time, the charge current at a first charge current Ii from the charging apparatus 10 via the contacts 32 and 34 is first transmitted to the electronic device 12 and therefrom to the battery ^¬ mulator fourteenth The electronic device 12, in particular its charge control device, determines the type and state of charge of the battery 14 using the data transmitted from the battery via the contact 40, if not already known, converts this data via the converter 26 and transmits this data to the control device 24 On the basis of the received data, the latter controls the switch 22 in such a way that the charging current supplied by the charging device 10 pulsates. In other words, the charging circuit is alternately interrupted by the control device 24 temporarily opening and closing the switch 22. The control of the switch 22 by means of the control unit 24 takes place in such a way that charging current data are encoded in the resulting charging current pulse sequence, which are decoded by the pulse detection device 20 and on the basis of which the current control device 18 controls the variable current source 16. In this way, the electronic device 12 can inform the charging device 10 of the type and state of charge of the rechargeable battery 14 to be charged, so that the current control device 18 can set the variable current source 16 in accordance with this information.

To increase security, it can be provided that the charging device 10 transmits the result of the determined charging current data back to the charging control device, that is to say confirms it, and only after the correctness of this data has been confirmed again by the charging control device in the frame the electronic device 12 is a continuation of the charging process takes place ^¬.

This initialization described above, i.e. the transmission and _Ü is carried out, if desired, confirmation of th Ladestromda ^¬ with a charging current with the current strength Ii wah ^¬ rend the period between the times t ₀ and t, that is during the time period Δti. After the transfer of the charging current data has been completed, the charging current is then increased to a significantly higher value I ₂ , which is matched to the determined type and state of charge of the accumulator 14 for rapid and at the same time gentle charging.

Figure 2 now shows two special cases, which can occur during charging. On the one hand, FIG. 2 shows that in the event of an incorrect initialization process, i.e. when no plausible charging current data could be received by the charging device, a charging current I _{3 is set} after the time period Δti has elapsed, with which charging current I ₃ the rechargeable battery 14 to be charged is charged as standard becomes. This measure ensures that even if no type of battery and / or state of charge that is plausible for the charging device 10 can be determined on the basis of the transmitted charging current data, the battery is still charged, but with a current intensity I _{3 that is} reduced compared to the current intensity I. This can ensure that the unidentified battery 14 is nevertheless charged in acceptable time without damage.

If one now looks at the middle area of FIG. 2, one can see the processes when the charging process is interrupted. The interruption takes place at time t ₂ . If the charging process is interrupted, two cases are provided. If the interruption lasts for a predetermined time period Δt ₂ to time t ₃ or longer, the initialization phase already explained above with reference to the time period between t ₀ and t _L begins again in which the charging current data are transmitted and the ideal charging current for the current state of charge of the battery is determined. On the other hand takes the interruption of the charging ^¬ operation shorter than the time period At _2, as indicated in Figure 2 by the dotted line, the charging process is continued with the same current as before the interruption, that is, as before the time T _2. This means that depending on the existing charging process, i.e. depending on whether a successful charging current data transfer (initialization) could take place or not, either with the charging current I ₂ (with successful charging current data transfer) or with the charging current I ₃ ( if the charging current data transmission is faulty) the charging process is continued.

The invention shows a methodally and hardware-wise simple, but reliable and in particular adapted to the respective battery to be charged, quickly and gently charging the battery to be charged.

Claims

claims

1. A method for loading a Ladekontrollemrich- with a device (12) coupled to the accumulator (14) by means of a La ^¬ devorrichtung (10), characterized by the steps of:

D) supplying a charging current with a first current strength (Ii) over a predetermined initialization time period

E) exchanging data between the charging contacts charging current trollemπchtung (12) and the charging device (10) wah ^¬ rend the initialization time period, and

F) feeds a charging current with a according to the La ^¬ destromdaten selected second current intensity (I _2, I ₃₎ / the charging current data during the initialization period of time (Δti) encoded by pulsed transmission of the charging current with the first current strength (Ii) transmitted ,

2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the charging current data state, in particular state of charge, and type of the accumulator (14) characterizing information.

3. The method according to claim 1 or 2, d a d u r c h g e k e n e z e i c h n e t that the pulsed transmission takes place by temporarily interrupting the charging current by means of the charging control device (12), wherein the charging device (10) determines the charging current data from the current pulses.

4. The method according to claim 3, characterized in that the charging device (10) in step B) confirms the charging current data determined from the pulses by pulsed transmission of the charging current.

5. The method according to any one of the preceding claims, characterized in that the first current (I,), preferably by half, is less than the second current (I ₂ , I ₃ ).

6. The method according to claim 5, characterized in that the first current (Ii) between 50mA and 200mA, preferably ^¬ preferably 100mA, and that the second current (I ₂ I) is between 500mA and 2A, preferably 1.5A.

7. The method according to any one of the preceding claims, characterized in that in the event of missing or incorrect exchange of the charging current data, a predetermined second current intensity (I ₃ ), preferably of approximately 700 mA, is set.

8. The method according to any one of the preceding claims, characterized in that when the charging current is interrupted for a second time period (Δt ₂ ) or longer, steps A) to C) are carried out again.

9. The method according to any one of the preceding claims, characterized in that when the charging current is interrupted for less than the second time period (Δt ₂ ), step C) is carried out with the last set second current intensity (I ₂ , I ₃ ).

10. Device (10) for charging a rechargeable battery (14) coupled to a charging control device (12), in particular according to the method according to one of the preceding claims, comprising: a changeable current source (16) for providing a current with which the rechargeable battery (14 ) is to be charged, a current control device (18) for controlling the changeable current source (16) and a pulse detection device (20) for evaluating charging current pulses, characterized in that the pulse detection device (20) monitors the charging current for charging current data output by the charging control device (12) in the form of charging current pulses and that the current control device (18) controls the current source (16) to set the charging current in accordance with the charging current pulses evaluated by the pulse detection device (20).

11. The device (10) according to claim 10, so that the charging current data contains status, in particular charging status, and type of the accumulator (14) characterizing information.

12. The device (10) according to claim 10 or 11, so that the current control device (18) is designed to operate the current source (16) in a pulsed manner to confirm the charging current data with respect to the charging control device (12).

13. A mobile electronic device (12), in particular a mobile radio terminal, comprising a charge control device (12) and an accumulator (14) for interacting with a device (10) according to one of claims 10 to 12, characterized in that the charge control device (12) has a switch (22) for interrupting the charging current and a switch control device (24) controlling the switch (22), the switch control device (24) for generating charging current data in the form of charging current pulses in accordance with the state, in particular the state of charge, and the Type of the accumulator (14) controls.