DE19913627A1 - Electric battery charging method - Google Patents

Abstract

The battery charging method uses a variable energy source, e.g. a solar module (11), for providing a variable charging energy, which is converted into defined current pulses and pulse pauses before being supplied to the battery. The energy from the solar module may be stored temporarily by a storage capacitor (13) before being converted into current pulses with a constant pulse amplitude and/or pulse width via a pulse generator (20), with variable pauses between the current pulses.

Description

The present invention relates to a method and a Device for charging an accumulator using a varia blen energy source. Furthermore, the invention relates to a ver drive to check the state of charge of a battery.

Accumulators are rechargeable batteries in addition to a wide range of possible applications For example, they can also be used as a buffer for solar operation driven consumers can be used. Such solar companies Consumers get their energy from a solar module. To consumers even in phases without lighting with Ener To be able to supply, additional batteries are often used gates based on lithium (Li) or nickel (Ni) puts. However, the nickel-based batteries have the problem that if the supply of charging current is not constant, as it can be with a solar module, one suitable charging and charging monitoring of the batteries not possible.

Nickel-based batteries are usually made after the Constant current method loaded. The typical course of the loading / Discharge cycle of a nickel-based battery runs such that the voltage increases during constant current charging then climbs steeply, then flows into a plateau. Wuh rend this "plateau phase", in which most of the acti If the electron mass is charged, the span changes only insignificant. The end of the charge announces itself at nickel-based accumulator by a subsequent buc cone-shaped voltage curve. During this hump-shaped The internal chemical takes on increasing course of tension  Short circuit of the oxygen circuit on the charging current. To when the voltage drops, the charging current must then be switched off become.

Because the user has a reliable indication of the state of charge also in the plateau area, that is in the range of about 10 to 70% of the nominal capacity of the accumulator is the value the accumulator cell voltage unsuitable for such a display net. At most the voltage hump at the end of the charging phase can be used in an automated loading process to recognize the Serve the end of charging.

Are nickel-based accumulators several times after only part wise discharge recharges, so their Capacity increasing. This phenomenon is observed when the discharge can be ended above 1.1 V. she is called "memory effect" because the accumulator seems to recall the previous partial discharges. In the event of such a loss of capacity of the accumulator some cycles with a final discharge voltage well below half 1.1 V to the original capacity restore. An equally reversible Kapa Loss of quality becomes more severe, especially with increased Temperature of overloading of the nickel-based battery accumulator detected.

All charging modules available so far are based on the Kon principle and evaluate the voltage curve during the Charge off. Prerequisite for sufficient charge monitoring chung is that actually during the entire charging a constant charging current also closes. Will the current interrupted or in the meantime decreases once, so the accumulator voltage drops at the same time and it becomes the end of loading determined. Especially with a solar battery  However, the charging current is not constant and it can these charging modules are not used.

A well known way to build an accumulator with a solar is to load the module directly with a protective diode Connect solar module. In this case there is no drawer monitoring given. However, one can have a maximum tension specify in which the accumulator then ge from the solar module is separated. A partial load that produces the "memory effect" produ graces, but cannot be prevented.

Based on the state of the art, the present ing invention the task of a method and Device for charging an accumulator using a varia blen energy source, as well as a procedure for checking To create state of charge of an accumulator, in which the described disadvantages can be avoided. In particular, should a charge and a check of the state of charge of the battery lators even with a non-constant charge current supply per can be easily carried out.

This object is achieved according to the first aspect of the invention by a method for charging an accumulator by means of egg ner variable energy source solved that according to the invention is characterized by that of the variable energy Source generated energy in defined current pulses and pulse spau sen converted and fed to the accumulator in this form becomes.

This results in a gentle loading process for the accumulators. In particular, but not exclusively, is the inventive method for loading nickel-based Batteries suitable by means of solar modules. By inventing The method according to the invention makes it possible for the accumulator optimal even with a non-constant charge current supply  will load without affecting life duration or capacity loss of the battery can.

There is a basic idea in the method according to the invention in that the La. generated by the variable energy source of different levels into defined current pulses and Pulse breaks are converted. By the defined setting the current pulses and the duration of the pulse pauses the accumulator always with a sufficiently high, constant Charging current supplied. Is the charging current interrupted or if it does decrease in the meantime, it becomes over the length the pulse pauses reflected, so that a drop in the accumulation gate voltage, which cause an end of the charging process would be prevented. In this way, phenomena like det described "memory effect" or the like prevented become. By the inventive method for loading the It becomes accumulator even when using variable energy sources of energy now possible, known monitoring methods to monitor the charge status of the battery the.

With the method according to the invention, the accumulator can do so charged with using a modified constant current method become.

Preferred embodiments of the method result from the subclaims.

The one generated by the variable energy source is advantageous Energy stored in a capacitor.

The current pulses by means of a pulse generator are advantageous tors generated.  

If the energy generated in a capacitor interposed is saved, it becomes possible to use the pulse generator Accumulator to supply current pulses.

These current pulses are preferably in their pulse height and Pulse width constant. The not constant charging currents like them then occur when using solar modules advantageously reflected in that the pulse pauses between the individual current pulses are variable. If as a variable A solar module is used to power the pulse breaks in high sunshine can be very short. At ge Ringer sun exposure then the pulse breaks are longer.

The variable energy source as a solar module is advantageous educated. Among other things, solar modules have a number of Solar cells on, and can, for example, in one appropriate consumer or integrated externally via a Ka be connected to the consumer. However, it is Invention not limited to solar modules, so that other re variable energy sources are conceivable and possible.

The accumulator is advantageously made of nickel.

According to the second aspect of the present invention, a Procedure for checking the state of charge of an accumulator provided, in particular by means of one as above described method for charging a battery becomes. The method is characterized according to the invention net that to check the state of charge of the voltage curve measured in the accumulator in response to the current pulses and is evaluated.

This makes it possible for the user to be reliable Display of the state of charge in the plateau area of the con  Current method, that is in the range of 10 to 70% of Receives nominal capacity of the battery.

The method according to the invention furthermore achieves that the battery is charged even with a variable charging current offer can be checked accurately and reliably. To the Advantages, effects, effects and how it works method according to the invention is based on the above stungen to the inventive method for charging a battery mulators by means of a variable energy source Referenced and hereby referred. To charge status Different options are possible bar, which are described in more detail below.

The measurement and evaluation of the voltage curve as a reaction the current pulse is usually used as an impulse response draws.

Preferred embodiments of the method according to the invention result from the subclaims.

The size and / or shape of the voltage jumps is advantageous measured and evaluated. It is based on the basic idea Made use of that the impulse responses in the area of Nor charge are independent of the charging current. The shape and size however, the impulse response changes with increasing charging was standing. At the beginning of the charging process, the voltage jumps that is the difference of the accumulator voltages in the current pulse and large in the pulse pause. With increasing charge of the Accumulator decreases this difference, goes through a minimum and rises again towards the end of loading. This behavior can then be used for charge monitoring.

In a further embodiment, it can be in the pulse pauses voltage can be measured and evaluated. After abcline  The charging current pulse is usually the same weight and no more currents flow. In this Si The chemically relevant open circuit voltage of the Ak accumulator can be measured. In a preferred embodiment tion form, it is possible that the charge of the battery first started with a high charging current in the current pulses and is used until it is measured without resistance ne voltage in the pulse pauses has reached a limit value. Then the charge pulse heights are adjusted so that this voltage remains constant. This process is similar to the well-known "Resi stance free voltage method ".

After a current pulse, the Ab Sounding curve of the voltage measured in the pulse pauses and out be evaluated. Especially if the period between two successive current pulses down to the second extended the range, this allows the charge status refine the identifier. In this case, the langsa me decay of the accumulator voltage registered and from the his course concluded on the progress of the loading process become. Such a process is also called "Voltage Descend Expander" known.

The different ways to Charge status monitoring can be done individually, that is, un depending on each other, or in any combination leads. For example, two or three of the ge mentioned options applied at the same time, the Accuracy of a statement about the state of charge of the battery increase lators.

According to the third aspect of the present invention, a Device for charging an accumulator, in particular under Use of a method as described above for Charging the battery, and to check the state of charge  the battery, especially using a like Procedure for monitoring the drawer described above state, provided. The device has fiction according to an accumulator, a variable energy source and one Capacitor for temporary storage of the variable energy Energy source generated energy.

The accumulator can be adjusted to such a device simple and even way with a variable La can be loaded without reducing the lifespan of the Accumulator is reduced or a "memory effect" can adjust. The advantages, effects, effects and the mode of operation of the device according to the invention is based on the above statements on the verse according to the invention drive to charge the battery and to the invention Procedure for checking the state of charge of an accumulator Full reference and hereby referenced.

Preferred embodiments of the device according to the invention tion result from the subclaims.

A sensor element for measurement and evaluation is advantageous of the voltage curve provided in the accumulator. It is the invention does not apply to certain embodiments of the Sen limited. The sensor element can be used as required be connected to a suitable evaluation device, in which evaluates the values measured by the sensor element and may be displayed.

The sensor element can advantageously be used for measurement and evaluation the size and / or shape of the voltage jumps his.  

In a further embodiment, the sensor element can be used for measurement and evaluation of the voltage present in the pulse pauses be trained.

The sensor element can also advantageously be used for measuring and off evaluation of the after a current pulse in the Decay curve of the voltage which sets pulse pauses det be.

The variable energy source is preferably a solar module educated.

In a further embodiment, the accumulator can be made of nickel ba be trained.

The invention will now be described on the basis of exemplary embodiments Reference to the accompanying drawing explained. It demonstrate:

Figure 1 is a schematic view of an inventive device for charging an accumulator.

Fig. 2 is a diagram showing a pulse pattern for charging the battery; and

Fig. 3 is a diagram in which impulse responses of the accumulator are presented at different charging states and charging currents.

In Fig. 1, a device 10 for charging an accumulator is shown. The device 10 initially has a variable energy source 11 designed as a solar module. The variable energy source 11 is connected via a line 14 to an integrated charge controller 19 . The integrated charge controller 19 has a pulse generator 20 and a Stromreg controller 21 for a consumer 15 . The integrated Ladereg ler 19 is connected via a line 16 to a battery 12 , which in the present exemplary embodiment is designed as a nickel-based battery. Both the accumulator 12 and the variable energy source 11 are connected via a line 17 to a consumer 15 . If there is sufficient solar radiation, so much power is generated by the variable energy source 11 designed as a solar module that the consumer 15 can be operated with it. At the same time, the accumulator 12 is also charged via the variable energy source 11 . If the solar energy radiating into the solar module 11 is not sufficient to operate the consumer 15 , the consumer 15 is operated via the battery 12 .

In order to ensure a uniform charging of the battery 12 and an advantageous monitoring of the state of charge of the battery 12 even when the supply of charging current from the solar module 11 is not constant, a capacitor 13 is provided. The electrical energy generated by the solar module 11 is first temporarily stored in the capacitor 13 . This makes it possible to supply the accumulator 12 with current pulses generated by the pulse generator 20 which are constant in their pulse height and pulse width. The non-constant charging currents are then reflected by the fact that the pulse pauses between the individual current pulses can vary. In this way it is prevented that the lifespan of the accumulator 12 is shortened or that the so-called "memory effect" can occur in it.

In line 14 , a protective diode 18 is hen hen vorgese. This prevents the capacitor 13 from being discharged from the solar module 11 if the solar radiation is insufficient.

The current regulator 21 for the consumer 15 has, inter alia, the function of preventing the accumulator 12 from being deeply discharged by the consumer 15 .

A method for charging the rechargeable battery 12 and a method for monitoring the state of charge of the rechargeable battery 12 will now be described below.

As already described above, the energy generated by the solar module 11 is converted into current pulses, which are then fed to the accumulator 12 . An exemplary pulse pattern for charging the accumulator 12 is shown in FIG. 2. A current pulse of 1 CA was set in order to obtain a sufficient extension of the impulse response. This current pulse is held for a period of 6 seconds in each case in order to register a clear, demonstrable increase in the voltage. After the end of the current pulse, there was a pulse pause of variable duration. In the present exemplary embodiment, these pulse pauses were varied between 54 seconds and 24 seconds in such a way that an arithmetic mean value of the charging current of 0.1 CA and 0.2 CA was shown in FIG. 3. To charge the accumulator 12 , the current pulses defined in FIG. 2 were supplied to this.

In Fig. 3 different impulse responses of the accumulator 12 are shown with different charging states and charging currents Darge. These impulse responses are voltage states in the battery mulator 12 , which are set in response to the current pulses of the La destroms. FIGS. 3a to 3c each impulse responses 12 at an arithmetic average of the charging current of 0.1 CA is the Figure 3d to 3f represent impulse responses of the battery 12 at an arith metic average of the charging current of 0.2 CA illustrate the accumulator... in FIGS. 3a and 3d impulse responses at the beginning of La devorgangs are shown of the battery 12 respectively. Figs. 3b and 3e show impulse responses that were taken after about a quarter of the charging process. In Figs. 3c and 3f impulse responses are finally displayed to the end of charging of the battery 12.

As can be seen from the various measurement curves, the impulse responses are essentially the same regardless of the charging current and the respective charging states. The impulse responses, however, change in the course of the charging process, although charging was always carried out with the same current pulse shown in FIG. 2.

At the beginning of the charging process ( Fig. 3a, 3d), the voltage jumps are very large. The impulse response initially rises steeply, then flattens out in the further course and then runs out in a decay curve after the end of the current pulse before it rises sharply again through the next current pulse.

In the further course of the charging process, the size and shape of the impulse responses to the current pulses change, as is shown in FIGS . 3b and 3e. As can be seen from these figures, the size of the impulse responses decreases to a minimum. If the accumulator 12 is charged, for example, with the constant current method, these minima of the impulse responses occur during the charging period in which the accumulator 12 is in the "plateau region" of the charge curve. As has already been described in more detail above, this is the range from approximately 10 to 70% of the nominal capacity of the accumulator 12 .

By measuring the voltage curve shown in FIG. 3 in response to the current pulses, it is possible to be able to check the state of charge of the accumulator 12 even in the “plateau area”.

Towards the end of the charging process ( FIGS. 3c, 3f), the voltage jumps become larger again due to the current pulses. Due to this renewed high increase in voltage jumps, it can now be concluded that the accumulator 12 has reached the end of the charging process.

Suitable, not shown, sensor elements can be provided for measuring and evaluating the different voltage curves which result in response to the current pulses during the charging process of the accumulator 12 . These sensor elements can measure the size and / or shape of the voltage jumps, for example. Furthermore, it is possible for the voltage present in the pulse pauses to be measured and evaluated via the sensor elements. Finally, it is also conceivable that the sensor elements for measuring and evaluating the decay curve of the voltage which arises after the end of a current pulse in the pulse pauses are formed. Depending on the need and application, the individual sensor elements can be used either alone or in any combination.

The provision of current pulses according to the invention with a constant pulse height and pulse width as well as variable pulse pauses makes it possible to charge the accumulator 12 without problems even when the charging current supply is not constant. At the same time, it is possible via the data generated by the current pulses through the charging time in the accumulator 12 different impulse responses, to make accurate statements about the charging status of Akkumula tors 12th The life of the battery 12 can thus be increased and the occurrence of the "memory effect" can be reduced.

Claims (18)

1. A method for charging an accumulator ( 12 ) by means of a variable energy source ( 11 ), characterized in that the energy generated by the variable energy source ( 11 ) is converted into defined current pulses and pulse pauses and is supplied to the accumulator ( 12 ) in this form. 2. The method according to claim 1, characterized in that the energy generated by the variable energy source ( 11 ) is temporarily stored in a capacitor ( 13 ). 3. Apparatus according to claim 1 or 2, characterized in that the current pulses are generated by means of a pulse generator ( 20 ). 4. The method according to any one of claims 1 to 3, characterized ge indicates that current pulses with constant pulse height and / or pulse width are generated. 5. The method according to any one of claims 1 to 4, characterized ge indicates that the pulse pauses between the individual Current pulses are variable. 6. The method according to any one of claims 1 to 5, characterized in that the variable energy source ( 11 ) is designed as a solar module. 7. The method according to any one of claims 1 to 6, characterized in that the accumulator ( 12 ) is formed on a nickel basis. 8. A method for checking the state of charge of an accumulator ( 12 ), which is loaded by means of a method according to one of claims 1 to 7, characterized in that for checking the state of charge the voltage curve in the accumulator ( 12 ) measured in response to the current pulses and evaluated. 9. The method according to claim 8, characterized in that the Size and / or shape of the voltage jumps measured and from is evaluated. 10. The method according to claim 8 or 9, characterized in that the voltage present in the pulse pauses is measured and is evaluated. 11. The method according to any one of claims 8 to 10, characterized ge indicates that after the end of a current pulse the Decay curve of the voltage measured in the pulse pauses and is evaluated. 12. Device for charging an accumulator ( 12 ), in particular using a method according to one of claims 1 to 7, and for checking the state of charge of the accumulator ( 12 ), in particular using a method according to one of claims 8 to 11, with an accumulator ( 12 ), a variable energy source ( 11 ) and a capacitor ( 13 ) for temporarily storing the energy generated by the variable energy source ( 11 ). 13. The apparatus according to claim 12, characterized in that a sensor element for measuring and evaluating the voltage curve in the accumulator ( 12 ) is provided. 14. The apparatus according to claim 13, characterized in that the sensor element for measuring and evaluating the size and / or the shape of the voltage jumps is formed.   15. The apparatus according to claim 13 or 14, characterized in net that the sensor element for measuring and evaluating the voltage present in the pulse pauses is formed. 16. The device according to one of claims 13 to 15, characterized characterized in that the sensor element for measuring and off evaluation of the after a current pulse in the Decay curve of the voltage which sets pulse pauses forms is. 17. Device according to one of claims 12 to 16, characterized in that the variable energy source ( 11 ) is designed as a solar module. 18. Device according to one of claims 12 to 17, characterized in that the accumulator ( 12 ) is formed on a nickel basis.