U.S. patent application number 12/459744 was filed with the patent office on 2009-12-17 for battery current charger.
Invention is credited to Jozsef Marinka-Toth, Attila Reisz, Viktor Rozsnyay.
Application Number | 20090309553 12/459744 |
Document ID | / |
Family ID | 26317978 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090309553 |
Kind Code |
A1 |
Marinka-Toth; Jozsef ; et
al. |
December 17, 2009 |
Battery current charger
Abstract
The object of the invention is a method for charging a
rechargeable battery having non-liquid electrolyte, which battery
has an internal resonance frequency. The charging process contains
at least one charging interval performed with current pulses, the
frequency of said current pulses is essentially identical with the
internal resonance frequency of the battery to be charged.
Following the charging interval consists of periodic current pulses
optionally a second relaxation interval is inserted, in which no
charging current is applied to the rechargeable battery, within
which optionally a second discharging interval is applied. After
the second relaxation interval the charging is performed in an
interval consists of a continuous charging current, whereafter an
optional first relaxation interval is inserted, within which
optionally a second discharging interval is applied. This sequence
of the above steps can be varied and applied repeatedly until the
full charge of the battery is attained.
Inventors: |
Marinka-Toth; Jozsef;
(Budapest, HU) ; Reisz; Attila; (Pilisjaszfalu,
HU) ; Rozsnyay; Viktor; (Budapest, HU) |
Correspondence
Address: |
Law Office of ROBERT C. KLINGER
2591 Dallas Parkway, Suite 300
FRISCO
TX
75034
US
|
Family ID: |
26317978 |
Appl. No.: |
12/459744 |
Filed: |
July 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10478815 |
Nov 26, 2003 |
7557541 |
|
|
PCT/HU02/00047 |
May 28, 2002 |
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12459744 |
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Current U.S.
Class: |
320/155 |
Current CPC
Class: |
H02J 7/00711
20200101 |
Class at
Publication: |
320/155 |
International
Class: |
H02J 7/04 20060101
H02J007/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2001 |
HU |
P0102198 |
May 24, 2002 |
HU |
P0201744 |
Claims
1. An apparatus configured to charge a rechargeable battery,
wherein the rechargeable battery has molecular cells and an
internal resonance frequency, the apparatus comprising: a current
generator configured to provide a non-DC charging current to the
battery during a first time interval, the non-DC charging current
configured to accelerate the molecular movement of cells.
2. The apparatus of claim 1 wherein the current generator is
configured to not provide the non-DC charging current during a
second time interval proximate the first time interval.
3. The apparatus of claim 1 wherein the current generator is
configured to provide a DC charging current during a second time
interval subsequent to the first time interval.
4. The apparatus of claim 3 wherein the current generator is
configured to provide the non-DC charging current during a third
charging interval subsequent to the second time interval.
5. The apparatus of claim 4 wherein the current generator is
configured to provide no current to the battery during a fourth
time interval occurring between the first time interval and the
third time interval.
6. The apparatus as specified in claim 1 wherein the non-DC
charging current has a frequency component that is a function of
the battery internal resonant frequency.
7. The apparatus as specified in claim 6 wherein the non-DC
charging current has a frequency component that is approximately
the battery internal resonant frequency.
8. The apparatus as specified in claim 1 wherein the current
generator is configured to generate the non-DC charging current as
a function of a control signal, further comprising a signal
generator configured to produce the control signal.
9. The apparatus as specified in claim 8 wherein the signal
generator is configured to produce the control signal comprising a
pulse train of pulses having a frequency corresponding to the
internal resonance frequency of the rechargeable battery.
10. The apparatus as specified in claim 1 wherein the apparatus is
configured to provide no voltage to the battery when the non-DC
charging current provided to the battery.
11. The apparatus as specified in claim 1 wherein the current
generator is configured to change the non-DC charging current
frequency component as the impedance of the battery changes during
charging.
12. The apparatus as specified in claim 11 wherein the frequency
component is a function of the battery internal resonant
frequency.
13. The apparatus as specified in claim 1 wherein the current
generator is configured to generate the non-DC charging current as
a function of a control signal, further comprising a signal
generator configured to produce the control signal.
14. The apparatus as specified in claim 13 wherein the non-DC
charging current has a frequency component configured to change as
the impedance of the battery changes during charging.
15. The apparatus as specified in claim 14 wherein the frequency
component is a function of the battery internal resonant
frequency.
16. The apparatus as specified in claim 13 wherein the apparatus is
configured to provide no voltage to the battery when the non-DC
charging current provided to the battery.
17. The apparatus of claim 14 wherein the current generator is
configured to not provide the non-DC charging current during a
second time interval proximate the first time interval.
18. The apparatus of claim 17 wherein the current generator is
configured to provide a DC charging current during a second time
interval subsequent to the first time interval.
19. The apparatus of claim 18 wherein the current generator is
configured to provide the non-DC charging current during a third
charging interval subsequent to the second time interval.
20. The apparatus of claim 19 wherein the current generator is
configured to provide no current to the battery during a fourth
time interval occurring between the first time interval and the
third time interval.
Description
CLAIM OF PRIORITY
[0001] This application is a Continuation of U.S. application Ser.
No. 10/478,815, filed Nov. 26, 2003, entitled Method and Apparatus
for Charging a Rechargeable Battery with Non-Liquid Electrolyte now
U.S. Pat. No. 7,557,541 the teachings of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] The invention relates to a method for charging a
rechargeable battery having non-liquid, but for example a gel
electrolyte, said battery has an internal resonance frequency. In
the course of charging a charging current is applied to a battery.
The invention relates furthermore to a circuit arrangement for
implementing the method of charging the battery having non-liquid
electrolyte, where an electric power supply is connected through a
current measuring device to the battery terminals.
BACKGROUND ART
[0003] Several methods are known for quick charging of batteries,
where the charging current is periodically interrupted and during
the pause on charging a short discharge or a load is applied to the
battery to be charged. The aim at these methods is to reduce the
duration of charging as much as possible and to increase the
lifetime of the battery by the proper maintenance and formation of
the storing cells.
[0004] The charge storing capacity of a battery is specified by Ah
ampere-hours. From this value a C5 value is derived by dividing it
by the time=ampere-hour/hour, so C5 has a current dimension. The
charging current of the battery is determined in proportion of C5.
For example, for a battery having 55 Ah capacity, C5=55 A. The
proper charging current of the battery is given in proportion of
C5, for example 0, 1.multidot.C5, in this case 5,5 A. In the
following description we use the term C5 in accordance with this
definition.
[0005] In the U.S. Pat. No. 5,600,226 patent specification a method
for controlling and terminating the charging of a battery is
described. In the course of this method the voltage is periodically
measured at the terminals of the battery and compared with the
result of the preceding such measurement, then based on the
difference of these two measurements the charged state level of the
battery is being determined. With this known solution, the charging
is periodically interrupted and during the pause of charging the
measurements are performed after a short discharge pulse. At the
beginning the charging is performed slower than the final charging
rate, at about 20% of this final rate, then by increasing the
charging pulse width the charging rate is increased to the
definitive charging rate. This method has been developed before all
to terminate the charging method at that point at which the battery
has attained a full charge. A rapid charging of the battery is
realized as well.
[0006] A similar rapid charging method is disclosed in the
international patent application no. WO 00/76050 A1, in that
solution however two successive discharge pulses are applied in
every charging interval. After each of the two successive discharge
pulses measurements are performed, to collect more accurate data on
the state of the rechargeable battery.
[0007] The object of the invention is to provide a method and
apparatus by means of which a faster charging of rechargeable
batteries can be achieved, than with the known methods.
DISCLOSURE OF INVENTION
[0008] It is well known that the reduction of the charging time is
limited by the slowness of the chemical transformations causing the
charging current inside the battery. If in the cells of the
rechargeable battery the rate of the chemical transformations can
be increased, the charging time can be reduced. Accordingly, the
object of the invention is to provide such a charging method, by
which the molecular movements in the cells of the rechargeable
battery can be accelerated and through this the time necessary for
the chemical transformations and the time necessary for the full
charge itself can be reduced.
[0009] It has been recognized that the intensity of pulsed charging
current applied to and taking of by a rechargeable battery is a
function of the frequency of the charging pulses, i.e. the
impedance of the rechargeable battery varies with the frequency.
Varying the charging pulse frequency, a peak charging current vs.
frequency of the battery can be found. The peak current frequency
varies from battery to battery and depends on their charged state.
The method according to the invention and the apparatus
implementing the method are based on this recognition.
[0010] The object of the invention set before has been attained by
means of the method in accordance with invention in such a manner,
that the charging process contains at least one charging interval
performed with current pulses, the frequency of said current pulses
is essentially identical with the internal resonance frequency of
the rechargeable battery to be charged. The duty factor of the
periodic current pulses is between 1:10 and 10:1 and the peak
current of said current pulses is in the range of 1.multidot.C5 and
7.multidot.C5. The duration of the interval of periodic current
pulses ranges between 200 ms and 1500 ms, where the frequency of
the periodic current pulses is within the range of 100 Hz and 10
000 Hz.
[0011] The advantage of this method consists in the fact, that when
charging with pulses at the resonance frequency of the rechargeable
battery the multiple of the usual charging current may be applied
without a significant heat dissipation and damaging the battery,
meanwhile an intensive internal molecular movement can be achieved
in the cells, which results in a significant acceleration of the
chemical transformation and of the charging of the battery.
[0012] According to a preferred embodiment of the method according
to the invention, following the charging interval consists of
periodic current pulses the charging is performed in an interval
consists of a continuous charging current, the duration of which is
ranging between 200 ms and 1500 ms, then a charging interval with
periodic current pulses is applied again. The interval consists of
said continuous charging current is performed within a current
intensity range of 1.multidot.C5 and 7.multidot.C5.
[0013] The advantage of this embodiment is that during the charging
with current pulses the battery is substantially prepared to accept
the intensive charging, then an intensive charging can be adapted
with the continuous charging current.
[0014] In a further preferred embodiment of the method according to
the invention between the charging interval with continuous current
and the subsequent charging interval with periodic current pulses a
first relaxation interval is inserted, in which no charging current
is applied to the rechargeable battery. The duration of the first
relaxation interval is not more than 1500 ms.
[0015] The advantage of this alternative embodiment is that during
the first relaxation interval the chemical transformations will be
further enhanced, then the following charging with periodic current
pulses will efficiently effectuate again the molecular movements in
the cells.
[0016] Within the first relaxation interval a first discharging
interval is applied, the duration of which is not more than 50 ms.
This discharging interval influences advantageously the charge
taking of capability of the rechargeable battery.
[0017] According to a further preferred embodiment, between the
charging interval consists of periodic current pulses and the
subsequently applied interval consists of continuous current a
second relaxation interval is inserted, in which no charging
current is applied to the rechargeable battery, the duration of the
second relaxation interval is not more than 1500 ms. Within the
second relaxation period a second discharging interval is applied,
the duration of which is not more than 50 ms.
[0018] In the apparatus implementing the method according to the
invention, the battery to be charged has an internal resonance
frequency and through a current metering device a power supply is
connected to the terminals of the rechargeable battery. In
accordance with the invention, in addition to the current metering
device between one of the battery terminals and the power supply a
controlled current generator is inserted, to the control input of
which a control signal is applied by means of a control circuit,
the intensity of the charging current applied through the current
generator to the terminal of the rechargeable battery is controlled
by means of said control signal.
[0019] According to a preferred embodiment of the apparatus
according to the invention, the control circuit provides a square
pulse having a frequency corresponding to the internal resonance
frequency of the rechargeable battery, said square pulse is applied
to the control input of the controlled current generator, said
current generator interrupts the charging current during the square
pulse spaces and during the pulses controls the charging current
flowing through the current generator to a value between
1.multidot.C5 and 7.multidot.C5. The duty factor of the square
pulse having a frequency corresponding to the internal resonance
frequency of the battery to be charged is in the range of 1:10 and
10:1.
[0020] According to another preferred embodiment the output of the
current metering device is connected to the control unit, on basis
of the feedback signal provided by the current metering device the
control unit controls the intensity of the charging current by
means of the current generator.
[0021] The current metering device is implemented by means of a
Hall-generator or simply by means of a resistor, the output signal
of which appears on the ends of the resistor.
[0022] To implement the discharge interval according to the
invention parallel to the terminals of the rechargeable battery to
be charged at least one discharging circuit is connected, which
consists of a series arrangement of a resistor and a controlled
switch. Accordingly, to the control input of said controlled switch
an output of the control unit delivering a pulse corresponding to
the discharging interval is connected.
[0023] The controlled switch is implemented with a known, fast
operating, preferably semiconductor device, for example by means of
a FET.
[0024] The charging of the rechargeable battery adapting the method
according to the present invention may be continued till its fully
charged state. The statement, sensing, displaying of the charged
state are not objects of this invention, for this purpose several
other solutions are well known.
[0025] The method according to the invention, as well as the
apparatus for the implementation of the method is now explained in
details below and reference is made to the exemplary embodiment,
shown on the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a graph depicting the charging current, as a
function of time in accordance with the simplest method of the
invention;
[0027] FIG. 2 is a graph depicting the charging current, as a
function of time in accordance with a second preferred method of
the invention;
[0028] FIG. 3 is a graph depicting the charging current, as a
function of time in accordance with a third preferred method of the
invention; and
[0029] FIG. 4 is the schematic circuit diagram of an apparatus for
the implementation of the method in accordance with the
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] The first and simplest possible preferred method according
to the invention can be followed in FIG. 1. On the horizontal axis
of the graph the time t, on the vertical axis the current I applied
to the terminals of the rechargeable battery are drawn up. The
charging current is supplied by an electric power supply applied
through a charging circuit to the terminals of the battery to be
charged, which power supply can be a rectifier connected to the AC
power line voltage, but any battery with higher voltage or similar
may be used as well. With this embodiment there are different
charging intervals inserted into the charging current, namely
interval a, which is a pulsed charging interval, followed by an
interval e, which is a charging interval with continuous charging
current.
[0031] The interval a is a charging interval consisting of charging
current pulses. The frequency of the pulse series is essentially
identical with the internal resonance frequency of the rechargeable
battery. This resonance frequency lies in the practice in the range
of 100 and 10 000 Hz, but rechargeable batteries with higher
resonance frequencies are also known. The duty factor of the
pulses, that is the signal/pause ratio may be chosen in the range
of 1:10 to 10:1. The duration of the interval a is preferably
within the range of 200 ms and 1500 ms. Within this range the more
exact duration has to be determined experimentally in compliance
with the type of the rechargeable battery.
[0032] In interval a the intensity of the Ip current pulses is
advantageously in the range of 1.multidot.C5 and 7.multidot.C5, the
value of which has to be determined also experimentally in
compliance with the type of the respective rechargeable
battery.
[0033] In interval a the rechargeable battery takes up a relatively
smaller charge, the pulse series of this interval substantially
prepares the cells of the rechargeable battery for taking up the
charge. The interval a is followed by an interval e, the duration
of which is preferably between 200 ms and 1500 ms, the optimal
duration of this interval has to be determined experimentally also
in compliance with the type of the rechargeable battery. Within
interval e the value of the charging current pulse Ic is constant
and its value is advantageously in the range of 1.multidot.C5 and
7.multidot.C5.
[0034] The optimal current pulse Ip within the interval a, the
charging current Ic within the interval e, as well as the duration
of interval a and the duration of interval e can be considered
constant. These values do not vary for rechargeable batteries of a
given type.
[0035] As can be seen in FIG. 1 the section consisting of the above
mentioned interval a and interval e repeats, that is after an
interval e follows again an interval a, then follows an interval e.
This process can be periodically repeated till the complete
charging of the rechargeable battery is attained.
[0036] In FIG. 2 a variation illustrated for the charging method of
the rechargeable battery, where the period consisting of the
interval a and interval e is followed by a relaxation interval p1,
during which no charging current applied. During this relaxation
interval p1 the internal chemical transformation of the
rechargeable battery promotes the more effective charge uptake. The
duration of the relaxation interval pl may be substantially very
short, preferably at most 1500 ms, the optimal duration of this
interval has to be determined experimentally also in compliance
with the type of the rechargeable battery. Following the relaxation
interval p1 follows again an interval a consisting of periodic
current pulse series. The sequence of intervals a, e and p1 repeats
periodically. This process can be repeated till the complete
charging of the rechargeable battery attained.
[0037] The charge take-up capacity of the rechargeable battery can
be increased, when during the relaxation interval p1 a short
discharge interval g is inserted, the duration of which is at most
50 ms. This discharge interval g is applied with at most 700 ms
delay after the interval e. The discharge is performed with a
limited -Id1 current, the intensity of which is at most
7.multidot.C5.
[0038] In FIG. 3 a further preferred embodiment of the method
according to the invention is shown, which differs from the method
shown in FIG. 2 in that, that between the interval a consists of
current pulse series and the continuous charging current interval e
a second relaxation interval p2 is inserted. The duration of the
relaxation interval p2 can be optionally short, as like as the said
relaxation interval p1, but their duration are not necessarily the
same. The maximal duration of the relaxation interval p2 is 1500 ms
too. Within the second relaxation interval p2 a second discharge
interval c is inserted, the duration of which is at most 50 ms.
This discharge interval c is applied with at most 700 ms delay
after the interval a consisting current pulse series. The discharge
is performed with a limited -Id2 current, the intensity of which is
at most 7.multidot.C5.
[0039] The method disclosed in connection with the before mentioned
examples not necessarily has to be applied in the full charging
time of the rechargeable battery. The charging time can be
effectively reduced even if the continuous charging current of the
rechargeable battery is interrupted by an interval a consisting of
current pulse series or by the intervals a to h or p1, p2 shown in
FIGS. 1 to 3 respectively.
[0040] The continuous charging can be desirable at the beginning of
the charging process in such cases, if a rechargeable battery is
completely or deeply discharged. With such batteries there is
mostly no resonance phenomenon. In such cases the rechargeable
battery is to be charged by continuous charging at least to such a
charge level, where the internal resonance of the rechargeable
battery can be detected and from this level the method shown in
FIGS. 1 to 3 can be effectively applied. However, rechargeable
batteries in continuous use, are usually not discharged to such a
deep level.
[0041] The circuit diagram of a battery charger apparatus according
to the invention implementing the method according to the invention
is shown in FIG. 4. The charging current applied to the
rechargeable battery 1 is supplied by an electric power supply 2 or
an other rechargeable battery with higher voltage, or similar
through a controlled current generator 3. Between the current
generator 3 and the rechargeable battery 1 a current metering
device 4 is inserted. Parallel to the terminals of the rechargeable
battery 1 a controlled loading unit is connected, which consists of
the series arrangement of a resistor 7 and a controlled switch 6,
the latter is preferably a semiconductor switching device, for
example a FET or a transistor or any other, fast operating
controlled switching element. The control input of the controlled
switch 6 is connected to the output Icd1 of the control circuit
5;
[0042] The method according to FIGS. 1 to 3 is implemented by a
control circuit 5, for example by means of a programmable function
generator. Accordingly, the control output Iv of the control unit 5
is connected to the control input of the current generator 3.
During the charging interval a consisting of periodic current pulse
series the said control output 1v provides a square pulse having a
frequency identical with the internal resonance frequency of the
rechargeable battery 1 to be charged, the amplitude of which is
proportional with the intensity of the pulse Ip. This square pulse
opens the current generator 3 during the pulse and applies current
pulses Ip to the rechargeable battery 1, the amplitude of which
square pulses is proportional to the charging current pulses Ip
applied through the current metering unit 4.
[0043] In accordance with the preferred embodiment of the invention
shown in FIG. 4 the positive terminal of the rechargeable battery 1
is connected to the voltage metering input Um of the control unit
5. The output of the current metering device 4 is connected to the
current metering input Im of the control circuit 5.
[0044] The current metering device 4 can be any known current
meter, such as a known Hall-generator, but a simple resistor,
schematically shown in FIG. 4 can be utilized too, on the ends of
which a voltage appears proportional to the charging current
flowing into the rechargeable battery 1, but any other known
current metering element can be utilized for this purpose. The
voltage on the current metering resistor shown in the example and
illustrated in FIG. 4 applied to the voltage measuring input Um and
the current measuring input Im of the control unit 5. By this
voltage the control unit 5 controls the amplitude of the square
pulse appearing on the control output Iv.
[0045] The frequency of the square pulses appearing on the control
output Iv can be set on the function generator of the control unit
or--if the battery charger is utilized to a given type of
rechargeable battery--it is set to a determined frequency.
According to the experiences the duty factor of the square pulses
may vary within the range of 1:10 and 10:1, which can be determined
more precisely experimentally in compliance with the type of the
rechargeable battery.
[0046] The function generator of the control unit 5 provides the
interval e in a similar manner, as well as the relaxation interval
p1 or the relaxation interval p2, shown in FIG. 3. During the
interval e appears a continuous signal at the output Iv, whereas
during the relaxation intervals p1 and p2 the current generator 3
is in closed state, does not forward any charging current.
[0047] In the course of the method according to the invention,
during the relaxation intervals p1 and p2 the optionally applicable
discharging intervals c and g respectively are implemented by means
of a serial discharge or loading circuit consisting of a resistor 7
and a controlled switch 6. For this purpose the control unit 5
supplies through its output Icd1 a pulse to the control input of
the controlled switch 6 produced preferably by the function
generator mentioned above, the duration of said pulses corresponds
to the duration of intervals c and g, respectively. On effect of
said pulse the switch 6 closes and a discharge current determined
by the resistor 7 and the voltage of the battery 1 loads the
rechargeable battery 1 for the duration of the pulse.
[0048] In the case when in the relaxation intervals p1 and p2 the
-Id1 and -Id2 discharging currents in the intervals c and g are
different, a further loading circuit will be connected parallel to
the terminals of the rechargeable battery 1 consisting of a
controlled switch 6' and a resistor 7'. The input of the controlled
switch 6' is connected to the output Icd2 of the control unit 5.
The loading circuits consisting of two different resistors 7 and 7'
loading with different discharge currents -Id1 and -1d2 the
rechargeable battery 1.
[0049] The control unit 5 may be completed in such a manner, that
preceding the charging a test can be performed on the rechargeable
battery 1. The test results can be stored and the charging can be
performed on basis of the stored data. For example, in a
preliminary testing period the function generator of the control
unit 5 provides a square pulse having a continuously varying
wobbulating frequency between 100 Hz and 10 000 Hz, the amplitude
of which is significantly lower than that of the square pulse used
during the charging, for example has a value of 0,1-C5. For this
reason between the power supply 2 and the current metering device 4
a series arrangement of a controlled switch 8 and of a resistor 9
is included, as shown in FIG. 4. The control input of the
controlled switch 8 is connected to an output It of the control
unit 5.
[0050] For testing purposes a low measuring current pulse series
has to be applied, with which it can be ensured, that when varying
the frequency the measuring charging current applied to the
rechargeable battery does not reach the saturation current even at
the resonance frequency. This current can be set by means of the
resistor 9.
[0051] The voltage proportional with the test charging current
having a wobbulating frequency measured by the current metering
device 4 appearing between the voltage metering input Um and the
current metering input Im is proportional with the internal
resistance of the tested rechargeable battery at the instantaneous
frequency of the square pulse. This measuring charging current
pulse series has a peak value in function of the pulse frequency,
which is the resonance frequency of the tested rechargeable
battery.
[0052] Of course the current generator 3, the switch 8 and the
resistor 9 can be integrated in a single circuit as well, with
which both the testing and the charging of the rechargeable battery
can be performed.
[0053] The method according to the invention is intended for use in
the charging of rechargeable batteries with non-liquid electrolyte,
such as Li-ion, NiCd, NiMH and lead batteries with gel electrolyte
(SLA).
[0054] Though the invention has been described with respect to a
specific preferred embodiment, many variations and modifications
will become apparent to those skilled in the art upon reading the
present application. The intention is therefore that the appended
claims be interpreted as broadly as possible in view of the prior
art to include all such variations and modifications.
* * * * *