BATTERY MANAGEMENT AND MONITORING SYSTEM
BACKGROUND OF THE INVENTION
Field of Invention
The field of the present invention relates to providing for equality of the battery voltages during the processes of battery charging and discharge.
Description of the Prior Art
It has been found that in batteries connected in a string, the batteries tend to vary in their ability to hold charge, during cyclic application of charge/discharge.
The above variations occur even if all batteries are carefully manufactured and appear to have no variations at the beginning of their life. Further with usage the variations between batteries tend to increase.
The increasing variation between individual batteries creates many difficulties. Since the battery tends to charge and discharge at different rates, particularly during operation, some batteries over charge or over discharge each when used or charged for the same period of time. The over charging or discharging of batteries reduces battery life and increases costs.
In extreme cases over discharge may lead to cell reversal and the battery may fail.
In certain cases there may be no alternative to identifying the weaker battery and repairing or replacing it. In order to do so it becomes necessary to identify the performance of each battery during charging and discharging and identify battery that needs repair or replacement.
The patents of the prior art address the above problem of over charging and/or over discharging of individual batteries. One method comprises:
(a) to, insofar as feasible, equalize the state of charge of all batteries by charging each battery to the point at which further charging does little to increase battery state of charge, and

(b) to, restrict depth of discharge.
US patent 6,150,795, discloses battery charge equalization which is carried out utilizing modules connectable in staggered relation between pairs of batteries in a series connected string of batteries. The drawback of the method of the above patent is that each a module is needed for each battery pair. If the weaker battery is far apart from the stronger battery, then many modules are required in between the weaker battery and the stronger battery, thus the efficiency of the system decreases.
US patent 5,003,244, discloses an apparatus that charges a plurality of batteries to equal voltage levels. The apparatus has a transformer that acts as a fly back circuit to charge the plurality of batteries. The transformer has a primary winding and a plurality of secondary winding circuits, each secondary winding circuit having a secondary winding and a diode. A different secondary winding circuit is coupled across each battery. The diodes cause only the battery having the lowest voltage among the plurality of batteries to receive energy on a transformer pulse. This occurs until that battery is charged to the level of the next lowest voltage battery, at which time both batteries will receive energy during the pulse. The sequence is followed until all the batteries are charged equally and to a predetermined threshold level.
The problem with the approach of the above patent is that the threshold level is detected by a voltage sense and charger control which is coupled across only one of the secondary winding hence it senses from one of the windings of the battery which is supplying to the corresponding battery this results in the improper charging of the rest of the batteries connected. Also the apparatus uses separate charger.
There is therefore a need to provide a Battery Management System which takes into account the average of sensed voltage of all the windings in order to allow proper charging of the batteries but at the same time utilizing a single source.
The above method and apparatus however wastes energy and reduces the effective energy storage capacity of batteries. Battery management system described here is intended for large battery packs where the individual cell or collection of cell voltages must be monitored and equalized.

An alternate solution is to monitor the performance of each battery during charging and discharging and to charge and/or discharge each battery separately and for different times. This solution is however costly and not suitable for many applications important to developing countries such as the use of battery in inverters or in e-vehicles.
There is thus need for energy efficient and cost effective product and process for providing for equality of the battery voltages during the processes of discharge and charge of the battery.
SUMMARY OF THE INVENTION
The invention of this Application discloses a product and process for providing for equality of the battery voltages during the processes of discharge and charge of the battery.
It will be noted that while the present invention is described with reference to batteries in a string, it would be evident to a person skilled in the art that the invention is equally applicable to multiple cells of a single battery.
During experiments it has been surprisingly observed that in case' during battery operation, the weaker batteries are supported in the manner described hereinafter, the problem of over-charging and discharging is mitigated and battery life increases. Further the invention permits the monitoring of the performance of individual batteries.
The term "weaker battery" as used above is meant to describe a battery, which in a given period of time during which the battery is charged (which time is less than the time needed to fully charge any battery) stores less charge than another batteries. The other batteries will be described as "stronger batteries". It will be noted that the terms "weaker battery" and "stronger battery" are relative and there can, for any battery string, be many "weaker batteries" and "stronger batteries".
A DC to DC Converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. The various converter topologies available are Boost, Buck, Buck-Boost, Fly back, Push pull, Half and Full Bridge or any other type known to the prior art. Any of the above converters can be used in embodiments of the present invention.

The PWM Controller comprised in this invention is a stand alone integrated circuit chip. The Master Controller comprised in this invention comprises:
a. the PWM Controller described above.
b. a data storage device.
c. a communication port. This port can be used to communicate the data
recorded through any means known to the art including wireless
communication (It will be noted that the terms "record", "data" and "data
recorded" are used interchangeably).
Optionally the Master Controller can be programmed to trigger off an alarm, which may be by way of sound or light or any other indication known to the art.
Such Master Controllers are well known to the art and are commercially available. Such Master Controllers may be general purpose microcontrollers or microprocessors or especially designed chips.
The invention of this Application will be described by means of embodiments given hereinafter. It will be noted that the embodiments are given only by way of example and are not meant to limit in any way the generality of the invention. The invention, as would be evident to a person skilled in the arts can be embodied in many other ways.
The first embodiment of this invention comprises a Battery Management System adapted for use with a plurality of batteries.
The Battery Management System comprises:
1) A DC to DC Converter comprising:
a. a primary winding;
b. a plurality of secondary windings. The number of secondary windings is
the same as the number of batteries with which the Battery Management
System is adapted to work;
c. a feedback winding such that the number of turns in the feedback winding
and in each of the secondary winding is the same.

2) A primary shunt electrically in series with the primary winding of the DC to
DC Converter.
3) A Pulse Width Modulator (PWM) Controller of a type known to the prior art.
The PWM Controller is electrically connected the feedback winding through a diode. Reference voltage for the PWM is the average voltage of the batteries with which the Battery Management System is adapted to work. The PWM Controller is programmed to ensure that the current flowing through the primary shunt does not exceed a pre-determined value and voltage across each secondary winding does not exceed a predetermined value.
4) The batteries are adapted to be electrically connected to the secondary
windings such that one battery is connected to one winding.
5) The ratio of turns between the primary winding and secondary windings is
approximately equal to the value of the average likely voltage of the batteries with which the Battery Management System is adapted to work.
Another embodiment of the present invention comprises the Battery Management System of the previous Embodiment 1 and further comprises secondary shunts.
Each secondary shunt is connected to the PWM Controller and electrically connected in series with a battery such that one secondary shunt is connected to one battery. The shunts protect the DC to DC Converter from the over drawl of current by the weaker battery.
Another Embodiment of the present invention comprises a Battery Management System adapted for use with a plurality of batteries, The Battery Management System of this embodiment comprises:
a) a DC to DC Converter comprising: a. a primary winding;

b. a plurality of secondary windings such that the number of secondary
windings and the number of batteries are the same;
c. a feedback winding;
b) a primary shunt,
c) a plurality of secondary shunts,
d) a Master Controller.
The primary shunt is electrically connected in series with the primary winding of DC to DC Converter and to the Master Controller.
The batteries are adapted to be electrically connected to the secondary windings such that one battery is connected to one secondary winding
The Master Controller is electrically connected to the feedback winding through a diode and to each secondary shunt.
The Master Controller is programmed to:
a ensure that the current flowing through the primary shunt does not exceed a pre-determined value.
b ensure that the voltage across each secondary winding does not exceed a pre-determined value.
c equality of battery voltages during the processes of discharge and charge of the batteries;
d monitor the performance of individual batteries by storing records in data storage device of the current flowing through the secondary shunts;
e communicate the records stored in the data storage device using communication port. Optionally the Master Controller can trigger off alarm as indicated hereinabove.
The use of the Master Controller ensures that it is possible to identify the weaker battery from the records kept by the Master Controller. In case it is found that a particular battery is consistently weak or deteriorating, the battery can be replaced.

It has been observed in practice that while the Battery Management Systems of the previous embodiments support the weaker battery, in case a large number of batteries is connected to a Battery Management System the support provided to the weaker battery may be less than the desired support.
An embodiment of the present invention relates to a Meta Battery Management System. This Meta Battery Management System is particularly useful when a large number of batteries are likely to be required.
A Meta Battery Management System of the present invention comprises:
a) a plurality of Battery Management Systems of- the previous embodiments;
b) a power bus;
wherein the Battery Management Systems are electrically connected to the power bus.
The power bus of this invention is any appropriate DC link known to the art.
In case the previous Embodiment comprises a Master Controller, the communication port of the Master Controller may be used to communicate data.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 describes an embodiment of the invention of this application comprises a DC to DC Converter along with a primary shunt and a set of batteries whereby the equality of the battery voltages during the processes of discharge and charge of the batteries is achieved.
Figure 2 describes another embodiment of the invention of this application which further comprises a secondary shunt and a PWM Controller whereby it is possible to detect the weaker battery in the string.
Figure 3 describes another embodiment of the invention of this application which comprises a Master Controller.
Figure 4 describes another embodiment of the invention of this application which comprises a Meta Battery Management System along with a PWM Controller.

Figure 5 describes another embodiment of the invention of this application which comprises a Meta Battery Management System along with a Master Controller.
DETAILED DESCRIPTION
This invention will further be described with reference to the embodiments hereinafter provided. The embodiments are by way of example only and are the invention can be embodied in many different ways as would be evident to a person skilled in the art.
The embodiments below are described with reference to three batteries. It would however be noted that the invention is general in nature and can work with any plurality of batteries. The number of batteries need not be limited to three or any other number. As the number of batteries changes the number of secondary windings and secondary shunts will also correspondingly change as would be evident to a person skilled in the art.
The battery of the present invention can be any battery known to the art. The battery can be a Lead Acid battery of any type, Lithium ion battery, Nickel Cadmium battery, Nickel Metal Halide battery. These battery types are given by a way of example only and are not intended to be a limitation on the invention.
EMBODIMENT 1
The first embodiment of this invention as described in Fig. 1 comprises a Battery Management System adapted for use with a plurality of batteries 301 A, 3Q1B and 301C.
The Battery Management System comprises:
1) A DC to DC Converter 101 which converter may be fly-back, push-pull, forward or any other type known to the art. The DC to DC Converter comprises:
a. a primary winding 111;
b. a plurality of secondary windings 121A, 122B and 123C.The
number of secondary windings is the same as the number of
batteries with which the Battery Management System is adapted to
work;

c. a feedback winding 131 such that the number of turns in the feedback winding 131 and in each of the secondary winding is the same.
2) A primary shunt 201 electrically in series with the primary winding 111 of the DC to DC Converter 101.
3) A Pulse Width Modulator (PWM) Controller 31 of a type known to the prior art. The PWM Controller 31 is electrically connected the feedback winding 131 through a diode (not shown). Reference voltage for the PWM is the average voltage of the batteries 301 A, 301B, and 301C. The PWM Controller 31 is programmed to ensure that the current flowing through the primary shunt 201 does not exceed a pre-determined value and voltage across each secondary winding does not exceed a pre-determined value. This pre-determined value of the current and the voltage are selected as follows:

1) the pre-determined value of the voltage is equal to the average likely voltage of the batteries 301A, 301B and 301C with which the Battery Management System is adapted to work;
2) the pre-determined value of the current is equal to the maximum power support expected to be provided to the weaker battery divided by the pre-determined value of the voltage given above.
4) The batteries 301A, 301B and 301C are adapted to be electrically
connected to the secondary windings 121 A, 122B and 123C such that
the battery 301A is adapted to be electrically connected in parallel
to secondary winding 121 A,
the battery 301B is adapted to be electrically connected in parallel
to secondary winding 122B,
the battery 301C is adapted to be electrically connected in parallel
to secondary winding 123C.

The ratio of turns between the primary winding 111 and secondary windings is approximately equal to the value of the average likely voltage of the batteries 301A, 301B and 301C with which the Battery Management System is adapted to work.
EMBODIMENT 2
Another embodiment of the present invention comprises the Battery Management System of Embodiment 1 and further comprises secondary shunts 231A, 231B and 231C as described in Fig.2.
The secondary shunts of this Embodiment can be of any type known to the art. Each secondary shunt is connected to the PWM Controller 31. Further shunt 231A is adapted to be electrically connected in series with the battery 301A; shunt 231B is adapted to be electrically connected in series with the battery 301B; and shunt 231C is adapted to be electrically connected in series with the battery 301C;
The shunts protect the DC to DC Converter 101 from the over drawl of current by the weaker battery.
EMBODIMENT 3
An embodiment of the present invention comprises a Battery Management System adapted for use with a plurality of batteries 301 A, 301B and 301C as described in Fig.3. The Battery Management System of this embodiment comprises:
a) a DC to DC Converter 101 comprising:
a. a primary winding 111;
b. a plurality of secondary windingsl21 A, 122B andl23C;
c. a feedback winding 131;
The DC to DC Converter of this embodiment is the same as that of the previous embodiments.
b) a primary shunt 201, of the same type as the previous embodiments.
c) a plurality of secondary shunts 231 A, 231B and 231C, of the same type as the previous embodiment;
d) a Master Controller 41 comprising:

a. a PWM Controller 31 of the previous embodiment;
b. a data storage device 32. The data storage device 32 is a device for recording
(storing) information (data). The storage device may hold information, process
information, or both. The data storage device 32 is adapted to store status
conditions of the said plurality of batteries.
c. a communication port 33. This port can be used to communicate the data recorded
through any means known to the art including wireless communication.
Optionally the Master Controller 41 can be programmed to trigger of an alarm so as to detect the weaker battery, which may be by way of sound or light or any other indication known to the art when the current flowing through a secondary shunt deviates from a preset value.
Such Master Controllers are well known to the art and are commercially available.
The primary shunt 201 is electrically connected in series with the primary winding 111 of DC to DC Converter 101 and to the Master Controller 41;
the batteries 301A, 301B and 301C are adapted to be electrically connected to the secondary windings 121A, 122B and 123C such that
the battery 301A is electrically connected in parallel to secondary winding 121A and in
series with the secondary shunt 231A,
the battery 301B is electrically connected in parallel to secondary winding 122B and in
series with the secondary shunt 231B,
the battery 301C is electrically connected in parallel to secondary winding 123C and in
series with the secondary shunt 231C,
The Master Controller 41 is electrically connected to the feedback winding 131 through a diode (not shown) and to each secondary shunt 231A, 231B and 231C through an optocoupler or some other device as would be evident to a person skilled in the art.
The Master Controller 41 is programmed to:
a ensure that the current flowing through the primary shunt 201 does not exceed a pre-determined value;

b ensure that the voltage across each secondary winding does not exceed a pre-determined value;
The pre-determined value of the current and the voltage are selected as follows:
1) the pre-determined value of the voltage is equal to the average likely voltage of the batteries 301A, 301B and 301C with which the Battery Management System is adapted to work;
2) the pre-determined value of the current is equal to the maximum power support expected to be provided to the weaker battery divided by the pre-determined value of the voltage given above.
c equality of battery voltages during the processes of discharge and charge of the batteries;
d monitor the performance of individual batteries 301A, 301B and 301C by storing records in data storage device 32 of the current flowing through the secondary shunts 231A, 231B and 231C respectively;
e communicate the records stored in the data storage device 32 using communication port 33. Optionally the Master Controller 41 can trigger off alarm as indicated hereinabove.
The use of the Master Controller 41 ensures that it is possible to identify the weaker battery from the records kept by the Master Controller. In case it is fovmd that a particular battery is consistently weak or deteriorating, the battery can be replaced.
EMBODIMENT 4
It has been observed in practice that while the Battery Management Systems of the previous embodiments support the weaker battery, in case a large number of batteries are connected to a Battery Management System the support provided to the weaker battery may be less than the desired support.

An embodiment of the present invention relates to a Meta Battery Management System described in Fig.4. This Meta Battery Management System is particularly useful when a large number of batteries are likely to be required.
A Meta Battery Management System of the present invention comprises:
a) a plurality of Battery Management Systems of embodiment 1 or
embodiment 2;
b) a power bus 100;
wherein:
the Battery Management Systems are electrically connected to the power bus 100. The power bus 100 of this invention is any appropriate DC link known to the art. EMBODIMENT 5
Another Meta Battery Management System of the present invention is described in Fig.5. The Meta Battery Management System of the present embodiment comprises:
a) a plurality of Battery Management Systems of embodiment 3;
b) a power bus 100;
wherein:
the Battery Management Systems are electrically connected to the power bus 100; and the communication port of the Master Controller 41 is used to communicate data.
The power bus 100 of this invention is any appropriate DC link known to the art.

I/We claim
1. A Battery Management System adapted for use with a plurality of batteries 301A,301B and 301C comprising:
a) a DC to DC Converter 101 comprising:
a. a primary winding 111;
b. a plurality of secondary windings 121 A, 122B and 123C;
c. a feedback winding 131;
b) a primary shunt 201;
c) a PWM Controller 31; wherein:
the primary shunt 201 is electrically connected in series with the primary winding 111; the batteries 301A, 301B, 301C are adapted to be electrically connected to the secondary windings 121A, 122B and 123C such that
the battery 301A is adapted to be electrically connected in parallel to secondary
winding 121A,
the battery 301B is adapted to be electrically connected in parallel to secondary
winding 122B,
the battery 301C is adapted to be electrically connected in parallel to secondary
winding 123C, the PWM Controller 31 is electrically connected to the DC to DC Converter 101.
2. The Battery Management System of claim 1 further comprising secondary shunts 231A, 231B and 231C.
3. A Battery Management System adapted for use with a plurality of batteries 301 A, 301B and301C comprising:
a) a DC to DC Converter 101 comprising:
a. a primary winding 111;
b. a plurality of secondary windings 121 A, 122B and 123C;
c. a feedback winding 131;
b) a primary shunt 201;
c) a plurality of secondary shunts 231A, 231B and 231C;

d) a Master Controller 41;
wherein:
the primary shunt 201 is electrically connected in series with the primary winding 111 of DC to DC Converter 101 and to the Master Controller 41;
the batteries 301A, 301B, 301C are adapted to be electrically connected to the secondary windings 121A, 122B and 123C such that
the battery 301A is electrically connected in parallel to secondary winding 121A
and in series with the secondary shunt 231 A,
the battery 301B is electrically connected in parallel to secondary winding 122B
and in series with the secondary shunt 23IB,
the battery 301C is electrically connected in parallel to secondary winding 123C
and in series with the secondary shunt 231C, the Master Controller 41 is electrically connected to the feedback winding 131 and to each of the secondary shunts 231A, 231B and 231C.
4. The Battery Management System of claim 3 adapted to trigger off an alarm.
5. A Meta Battery Management System comprising:

a) a plurality of Battery Management Systems of any of the claims 1 and 2;
b) a power bus 100;
,wherein the Battery Management Systems are electrically connected to the power bus 100.
6. A Meta Battery Management System comprising
a) a plurality of Battery Management Systems of any of the claims 3 and 4;
b) a power bus 100;
wherein the Battery Management Systems are electrically connected to the power bus 100.

7. The Meta Battery Management System of claim 6 as more particularly described in Fig.5.