FIELD OF INVENTION
The present invention relates to a battery charge equalizer for batteries connected in series to be equally charged. More particularly, the present invention relates to the charge equalization circuitry and method of charge equalization along with life enhancing desulphator circuit, comprising of monitoring, control and management of complete system.
RELATED ART
Repeated charge and discharge cycles of battery, lead to large non-uniformities in battery charge levels and corresponding differences in battery terminal voltages over a period of time because of slight differences in battery chemistry of an individual battery. During charging of a battery string composed of a series of batteries, some batteries will consequently reach full charge before others and before the overall battery terminal voltage reaches its nominal value. Such a process leads to overcharging of a subset of batteries. If these batteries are charged into the gassing phase, there can be significant degradation of the battery life. If a battery monitoring and recharging is done on a single-battery basis, it is possible to maintain each battery at its optimal operating point, and maximize battery life. Hence, it is common to provide charge equalization for all the batteries in a string.
The conventional battery charge equalizers are constituted with shunt resistors, which have a series of connected battery strings; resistors; switches; battery voltage sensing and controlling circuits. The battery voltage sensing and controlling circuits monitor the charging-discharging condition of each battery of the series connected battery strings. As any one of the batteries, for example the first battery has reached its pre-determined voltage value earlier than the others the battery voltage sensing and controlling circuits output a signal to turn on the switch letting a part of the current, which originally charges the battery pass through the resistor to maintain the battery voltage without overcharging it so as to avoid damaging the battery. Hence, the series connected battery strings can be charged to a proper voltage level without overcharging. But, this type of battery charge equalizer with shunt resistors will waste energy and are inefficient.

There is another type of conventional battery charge equalizer, which is constructed with a fly back converter with a transformer consisting of one primary coil and a number of identical secondary coils equal to a number of batteries, which draws out current from the whole battery system and directs the output energy to the batteries with the lowest voltage. Under ideal conditions, this system is in a standby mode. A simple comparator monitors the battery voltages. The fly back converter is activated as soon as one of the voltages deviates by more than a pre-determined tolerance value. A switch will be switched on and off with a high frequency and the energy will be transferred from the whole battery string via the transformer and the rectifying diodes to the individual battery. During this process, the battery with the lowest voltage will determine the voltages induced in the secondary coils. As all the coils are mounted on a common core, all the voltages induced in the secondary coils are equal, and the largest proportion of the secondary current will flow into the battery with the lowest voltage without the need for any additional selection logic, so that the charge of series connected battery strings can be maintained to a proper voltage without overcharging.
However, there are two drawbacks in this type of battery charge equalizer constructed with a fly back converter. One of them is that the battery charge equalizer constructed with a fly back converter requires a plurality of sets of secondary coils charged equally in a series connected battery strings with a plurality of batteries, which mounts all the coils on a common core to render all the voltages induced in the secondary coils equal. Thus the structure of the transformer is complicated and is difficult to manufacture. The other difficulty is that as the battery charge equalizer is constructed with a fly back converter, it is difficult to design a symmetric transformer of the fly back converter as each mounted coil on a common core has a plurality of sets in the secondary coil. So the effect of charge equalization is reduced. Furthermore, the type of battery charge equalizer constructed with a fly back converter in the various numbers of the batteries of the series connected battery strings is not conveniently adjustable. Diagnostic circuits have been proposed in some applications and are likely to be about as costly as the new equalization approach.
GB Patent no. 2337166 and US Patent no. 6064178 is using series RC circuit to store charge from batteries and further transfer it to lower charge battery but this patent employs R to charge and discharge the capacitor to achieve the object. Therefore, if substantial current increases then there will be power loss across R.
US Patent no. 6841971 using LC for achieving charge balance, but once again power loss will occur across L when it will be directly shorted (switched) to battery.
US Patent no. 2004113586 using single C to achieve charge balance between batteries. This will take much more time to balance the plurality of batteries serially connected and time will increase with increase in number of batteries.
WO Patent no. 2006082425A1 is a method of battery management system having switched mode fly-back dc-dc converter as active charge balancer. The drawbacks of such charge balancer are already discussed above.
US patent no. 20060012341 describes a battery management system, but it doesn't provide the facility of battery charge balancing to equalize the battery voltage of series connected batteries..
US Patent no. 2008018301 and 7288919 shows a voltage balance circuit/method, voltage-detecting circuit/method. In this, voltage balance is achieved through capacitors connected serially but of disadvantage of this circuit as shown in fig. 4 of the patent mentioned is the current passes through capacitor 58 may be in both directions. So resultant current will be less that reduces the amount of charge transfer and it results in long time required for charge balance. Also it is not possible to control the amount of charge transfer as per battery string state of charge demands. So, this results in more time for achieving the charge balance depending upon battery/cell capacity and state. The charge transfer control can be acnieved only by changing power transfer capacitor value in circuit as per battery charge state.
US Patent no. 5710504 is using active power transfer method to transfer power between battery string connected serially. In this patent also it is not possible to buck or boost the power transfer as per battery string state of charge demand. So this results in more time for achieving the charge balance depending upon battery/cell capacity. Buck or boost power transfer can be achieved only by changing power transfer capacitor value in circuit every time as per battery charge state/capacity. Battery state monitoring (battery management) is not done in this invention so customer alert is not possible through audio/visual messages. Further, data monitor of connected individual battery balancing unit is not possible and Auto/manual battery voltage sense and detection is not possible i.e. for 2V cell and 12V battery.
US Patent no. 6624612 is a method of active charge balance circuit, which has single charge transfer capacitor between series connected plurality of batteries. In this, charge transfer between batteries will take long time to balance whole string.
US Patent no. 20020190692/US6518725 provide a charge balance method using series connected capacitors along with digital switch in place of discrete power switch. So charge transfer between batteries will depend upon power carrying rating of digital switch, as it is known that digital switch have low power rating. So, it can he concluded that, this invention is suitable for low capacity batteries and it will take long time to charge balance higher capacity batteries.
Reference is to be made to a publication by Kutkut, N.H. et.al, Volume 2, Issue Page(s): 686 - 690, Feb 1998. The article discloses a new technique for equalizing a series battery stack using a modular non-dissipative current diverter.
Reference can also be made to a publication by Yuang-Shung Lee, IEEE, Oct 2002. The article explains a new bidirectional non-dissipative battery equalization scheme for the series battery strings.
Further, reference is to be made to a publication by Philip T. Krein et.al, IEEE, INTELEC, 2002. The article reviews battery behavior and performance related to the equalization problem, in the context of valve-regulated lead-acid batteries.
Reference is to be made to a publication of Battery power Online (Vol-8, issue5) by Jonathan Kimball and Brian Kuhn of Smart Spark Energy Systems, Inc., September 2004.
Reference may be made to a publication by Tsukamoto, K et.al, IEEE, Feb 1993. The article proposes an algorithm for improving the speed of a charge-balancing analog-to-digital converter implemented by a switched-capacitor technique.
Therefore, a practical apparatus and method should be capable of equalizing batteries during a charge cycle, during battery discharge, or during idle times. It is very desirable to avoid sensors or precise control so that simple, reliable, low-cost equalization circuits can be built. Preferably, no battery energy should be exchanged when the equalization process is complete. Also if the series string is charged as a unit, slight mismatches or temperature differences cause charge imbalance in the form of unequal voltages along the string. Once imbalance occurs, it tends to grow with time; low batteries charge less effectively and high batteries charge relatively quickly. It is necessary to ensure that if different batteries are at different power/ voltage levels, then balancing is done to get maximum utilization and thus better efficiency.
With all the above discussed restrictions or limitations, it is required to have an improved battery charge equalizer. In the nresent invention, the improved equalization technique ensures proper charge transfer to needy battery unit/cell by using proper capacitor-switch matrix to achieve the required charge balance of series connected plurality of battery string. Circuitry and control are simple and inexpensive. The amount of charge transfer is controlled through the control circuit based on the difference in charge state of the connected batteries. If the difference is large the charge transfer can be increased by
proper selection of switch matrix to reduce the time required to balance the batteries. In the present invention, any number of series strings of storage batteries can be equalized with N number of Equalizer unit. The system extends the life and capacity of the batteries. It is suitable for N numbers of batteries by utilizing multiple units together. The equalizer operates in all three modes i.e. battery charges, discharges or in idle mode.
In the present invention, a single unit is provided to fulfill the need of an equalizer, battery management and battery desulphator circuit. The battery equalizer starts functioning when the batteries are connected to the system the main controller is powered up and starts measuring the battery voltage, temperature and total battery string current sense through the ADC channels. The main controller decides how many batteries are connected and what the voltage difference between the batteries connected is. If the difference is above a defined threshold, the main controllers starts the equalization process by properly selecting the capacitor switch matrix based on the level of voltage difference between the batteries. If the difference is large, switches are selected so that large charge transfer takes place for fast equalization. The main controller also controls the desulphator circuit for generating high frequency current pulses to the batteries connected to remove the sulphate from the battery plates. The individual battery temperature is also measured if this temperature exceeds a high limit; high temperature warning/alarm is displayed for the respective battery. The status of all the batteries connected is displayed on LED /LCD. The total charging/discharging current of string is also measured. The display provides a graphical representation of key parameters like State of Charge, Battery health condition, current, voltage, temperature, AH In / AH Out, Depth of Discharge and Utilized Cyclic Life.
The battery equalizer provides complete monitoring, control and management of the battery connected. The main controller keeps track of the history of the battery states over a period of time. The battery equalizer can be connected together through the communication interface so that they can communicate with each other and the information of all other connected units can be shared and viewed on one master unit.
OBJECTS OF THE INVENTION-
The primary object of the present invention is to provide an intelligent charge equalization circuitry, comprising of a microcontroller/DSC based' control circuit which can monitor the charging voltage and control the charge transfer between batteries with unequal charge connected in a string so that each cell/battery can be kept in equal charged state which helps in extending the life of the batteries. Along with this, the invention also provides a battery management and monitoring system for the batteries connected with the system. It measures the voltage and total current of the system to indicate the current state of the system. The system gives indications such as whether the batteries are charging or discharging and the equalization process is under process or not. The temperature of the batteries is also monitored so as to give indication/alarm in case it crosses a threshold limit. The individual battery voltages are monitored continuously and based on that, the state of battery is defined. The same system also provides the battery desulphator circuit to desulphate the battery plates and improve and recover the charging and discharging capacity of the batteries. The battery equalizer keeps the voltage difference between the batteries/cells under limits to extend the battery life in any application.
Another object of the present invention is to provide a battery charge equalizer employing a numbers of the batteries in series thus forming a battery suing that is conveniently adjustable. The system can extend to any number of batteries and equalizers can be connected in a modular arrangement to equalize a large string of batteries/cells connected in series.
Yet another object of the present invention is to provide a battery charge equalizer using a controller to produce a set of pulse-width-modulation (PWM) signals.
Another object of the present invention is to provide a battery charge equalizer with controller to monitor state of each battery connected in series string.
Yet another object of the present invention is to provide a battery charge equalizer that can be used irrespective of the battery/cell technology such as chemistry, manufacturer, or capacity.
Still another object of the present invention is to provide a battery charge equalizer in which equalization process can be performed during the main charging, discharging or in idle condition.
Another object of the present invention is to provide a battery charge equalizer in which equalization takes place regardless of level of charge.
Yet another object of the present invention is to provide a battery charge equalization process that is controlled by the microcontroller/DSC based control section.
Still another object of the present invention is to provide a battery charge equalizer, which does not interfere with the safety or protection systems.
Another object of the present invention is to provide a battery charge equalization in which an identical implementation can be used in almost any situation.
Another object of present invention is to provide a controlled buck-boost power transfer scheme to balance a battery string by using appropriate Capacitor-Switch matrix with negligible power loss. This Capacitor-Switch matrix can be controlled depending on the level of charge difference of the connected batteries to achieve desired rate of power transfer which will result in better charge balance.
Another object of present invention is to provide a battery desulphator to further enhance battery life by removing the sulphate crystals form the battery plates as these crystals insulate the flow of electricity in the battery, degrading the capacity of the battery, reducing its charging and discharging capability over a period of time.
Still another object of the present invention is to provide a battery charge equalizer, which can display the status of all the equalizers simultaneously. This is achieved by serial intercommunication between the individual units.
STATEMENT OF INVENTION
According to this invention there is provided a battery charge equalizer connected to a plurality of batteries in series comprising of a control unit signaling a plurality of switches coupled to a number of capacitors, a current protection unit attached to the battery bank, a voltage/temperature/current sense unit and a PWM driver driving isolated multiple gate output along with the integrated battery desulphator circuit controlled by the control unit.
SUMMARY OF THE INVENTION
In order to overcome the mentioned problems and to achieve the said objects, the present invention provides an intelligent battery charge equalizer. In the present invention, a single unit is provided to fulfill the need of an equalizer, battery management and battery desulphator circuit. The main controller senses the voltage difference between batteries connected serially and accordingly switches ON/OFF the capacitor-switch matrix to transfer the charge between the battery with low charge and battery with high charge. The main control section monitors the battery voltages continuously and selects a proper combination of switch matrix based on the voltage difference between the connected batteries. If batteries have large unbalance, battery string gets balanced with more charge transfer. So battery balance time could be reduced and an effective balancing can be achieved. If there is a more charge unbalance between particular set of batteries, in that case particular set of batteries can be balanced with higher charge transfer between them. Decision for concern batteries is taken by the main controller.
The main controller also monitors the battery temperature through external temperature sensor and gives indication and/or alarm in case it crosses a threshold limit. The total current with which the batteries are charging or discharging is also measured with the system.
The system provides complete battery management system of the battery connected with the system. All the battery voltages and temperature are measured and the current state of the system is displayed with LED /LCD display. The system has an integrated battery desulphator, which is also controlled by the main controller. It works on the periodic basis and removes the sulphate oxides from the battery plates with the help of high frequency current pulses given to the connected batteries.
In the system capacitor switch matrix is selected in a manner to maintain charge transfer rate at maximum as it is observed that capacitor has their charge discharge life cycle. With greater charge-discharge cycles the charge storing capability of capacitor degrades over a period of time. Therefore, in order to maintain charge store and transfer efficiency of capacitor multiple set of capacitors are provided one set of capacitors works for a defined time period and another set of capacitor works after that and this process takes place alternately after predefined period.
An identical implementation can be used in almost any situation. For example, a switched-capacitor equalization circuit will work with lead-acid batteries, nickel-cadmium batteries, nickel-metal-hydride batteries, or other conventional rechargeable chemistries. Any kind of adjustment or recalibrations is not necessary.
In another aspect of present invention charge transfer rate could be increased or reduced as required according to the capacity of bakeries connected. This could be done manually or automatically.
The present system and method are usable irrespective of the battery technology. Voltage will be matched between adjacent batteries regardless of chemistry, manufacturer, or capacity. The present equalizer can be used with long series strings of batteries or even individual cells without limit. For U number of equalizer, maximum (3U+1) numbers of batteries can be connected.
In an aspect of the present invention, N series strings of storage batteries are used. The system extends the life, capacity of the battery and reduces battery replacement, which again reduces the cost. As the batteries are connected in series, it is easy to install. It is suitable for N number of batteries by utilizing multiple units together. The equalizer operates in all three modes i.e. battery charging, discharging or in idle mode.
In one aspect of the invention, a plurality of identical equalizing modules could be provided. The modules can be coupled to a plurality of batteries to be equalized.
The equalization process can be performed during the main charging process or separately. If desired, it can be performed continuously during battery operation with minimal power drain. Equalization takes place regardless of level of change. The process does not interfere with safety or protection systems, since charge is exchanged rather than delivered. Very little energy is manipulated at any given time within the equalization circuits. The main controller controls the process, when the difference in the battery voltages reduces below a defined threshold level. The equalization process is stopped once the difference increases above another threshold the process starts again. The concept is modular, and extends to arbitrary number of batteries. Modules could be provided as battery accessories could be packaged directly with individual batteries or individual cells. Batteries can be added without any system redesign by providing each additional battery with a module.
In another embodiment of the present invention, a single system could be designed for a broad range of nominal battery voltages. A single circuit can equalize batteries of wide voltage range.
In another embodiment of the present invention, display device can be liquid crystal display, light emitting diodes or any other display device.
In another embodiment of present invention, a buck-boost power transfer scheme is achieved by using appropriate capacitor-switch matrix.
In another embodiment of present invention, capacitor switch matrix could be increased to any number to achieve further desired buck-boost power transfer scheme for balancing the serially connected battery/cell string.
In another embodiment of the present invention the charge storage device equalized by the battery equalizer can be composed of a storage device other than batteries such as but not limited to double layer capacitors.
Further an embodiment of present invention, a single system is provided to equalize
plurality of 2V cell as well as 6V, 12V and 24V batteries connected serially. The
invention allows users to customize their equalization needs easily to fit their battery
configurations. For U number of equalizer, maximum (3U+1) numbers of batteries can be
connected.
Such as but not limited to:
For a single balancing unit, maximum number of batteries = (3 x 1) +1= 4
For two balancing unit, maximum number of batteries = (3 x 2) +1= 7
For three balancing unit, maximum number of batteries = (3 x 3) +1= 10
The foregoing as well as additional objects features and advantages of the invention will be more readily apparent from the drawings and their detailed descriptions.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows an overall block diagram illustrating a system and a method in accordance with the present invention;
Fig 2 shows Control section;
Fig 3 is circuit diagram of Power transfer cum current protection section.
Fig 4 is circuit diagram of Power transfer cum current protection section with different Capacitor-Switch matrix.
Fig 5 is the block diagram for the communication interface provided to collect the data from multiple equalizers connected in the system.
Fig 6 shows the block diagram for the battery desulphator circuit for the unit.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
Figure 1 illustrates a basic block diagram of the system in accordance with the present invention. The system is to be used with a plurality of series connected batteries 1. The system includes a control unit 2. A plurality of capacitors and switches coupled together in a matrix formation. The control unit 2, via control lines, provides signals to the plurality of switches.
In a representative embodiment, the control unit 2 is microcontroller/DSC or any other programmable device based PWM generator cum controller. A current protection unit 3 is also attached to the battery bank 1, which provides high current protection to the power supply section of the system 4. A PWM driver 5 controlled by main controller 2 drives isolated multiple gate output 6, which is connected to the power transfer section 7 which consist of capacitor switch matrix . This section is also attached to the current protection unit 3 to protect unit from high current.
A voltage, temperature, current sense unit 8 monitored by controller 2, is attached to the battery bank 1 which senses the voltage temperature rise and the string current of battery in order to protect connected battery bank 1 from abnormal condition. In-circuit program section 9 is to program the controller 2 in circuit from PC/Programmer. A communication interface section 10 having connectors is provided to receive and transmit the data messages from one equalizer unit to another or to an external system for monitoring and control of a numbers of battery equalizer units connected to N number of batteries connected serially. The display 11 unit shows the measured parameters of the connected system. A buzzer section 12 is provided which is fully controlled from central controller 2 and it provides alerts by giving continuous beep in case of abnormal conditions during
the operation. It reports irregularities in battery temperature, irregularities in battery voltage and provides detailed information on the number of life cycle used up corrected with temperature compensation. The battery desulphator section 13 is provided to desulphate the battery plates by providing high frequency pulse currents to the batteries connected. A single unit is made to fulfill the need of an equalizer and battery desulphator 13.
The controller 2 also monitors the charging discharging current of the battery string with current sensor 17 and with the help of this signal the controller can generate a signal from section 14 to inform any external system 16 such as battery charger, inverter or UPS etc to stop the charging current in case of abnormal conditions of the system such as high current, high temperature or high voltage etc.
The section 15 is the address selection switch combination for the address configuration of an individual unit for communication with each other and master unit. The controller 2 reads the address configured to the device for identification of device during communication. The device with the address zero is configured as master and communicates with all the connected systems to collects the information from all the systems.
Driver power supply circuit comprises of input voltage which is fed from battery bank connected with the system. The regulator herein has been used as a switch mode buck converter. A resistive voltage divider network is utilized to get desired voltage output, diodes at input are used to protect the circuit from being damaged in reverse polarity condition. Diode at output of regulator is a freewheeling diode and capacitors at input/output are used as a filter. The output is then fed to a linear regulator which generates for example a 3.3V /5V supply and is also fed to driver IC to switch isolated transformer to generate multiple gate drive outputs.
Power supply circuit: - To generate this supply of 5V a linear regulator has been utilized whose input is driver supply output. This circuit can give +5V to +3.3V (as desired). The circuit has overload and short circuit protection. The capacitors used have enough high
voltage rating to safely handle the input voltage fed to the circuit. Further, this supply is utilized to power-up all control section including main controller 2, in-circuit programmer 9, communication interface section 10, voltage/temperature sense circuit 8, display section 11 and buzzer drive section 12, display section 11, battery desulphator circuit 13.
PWM driver and isolated multiple gate drive output:-. Generation of the PWM signal is carried out by controller and fed to driver section to drive the isolated transformer primarily at desired frequency to generate multiple isolated gate drive output so as to drive power switches (Mosfets/IGBT/Transistor). Driver is finally controlled from main controller 2 and has multiple PWM input and output. Isolation of multiple gate drive output is done through transformer having one input winding and multiple isolated windings as output to drive plurality of power switches. Zener diodes and resistors are used to limit gate drive output of each winding at desired level. The controller also provides the PWM for driving the battery desulphator circuit.
The display section is an array of LED's/LCD connected to the controller. Tri color LED Display represents different messages related to battery voltage and temperature. A provision of connecting the LCD is also provided which shows the battery voltages, temperature and current state of the system.
Temperature sense circuit: - Temperature of individual battery can be measured by using external temperature sensor/thermistor. The sense signals of individual battery temperature are fed to the controller for monitoring and display purpose. These methods of sensing rely on the transfer of heat due to conduction and correspondingly change in resistance value. The thermistor is a part of resistor divider circuit; it's resistance changes with change in temperature so reference sense signal also changes with respect to change in temperature. Other type of temperature sensor such as RTD etc can also be used in the system. In case the temperature of any set of battery in string rises beyond predefined level, the battery equalizer may stop equalization process only for that set of batteries and an audio visual alarm is generated for user awareness and monitoring.
Voltage sense circuit:- It is used to sense the battery voltage level of the individual batteries in bank. The resistor network prior to the controller ensures that the battery bank voltage is calculated over its full range and in this way individual battery voltage sense signal is fed to the controller. The controller senses and records these levels to check the battery levels during charging mode, discharging mode and in idle mode. Central controller continuously monitors battery status and corresponding messages appears over display panel. In case of abnormal battery voltage condition it displays the current state with buzzer signal and may send a signal to the charging circuit to stop the charging process in case of abnormal battery voltage.
Buzzer section :- Buzzer is fully controlled from central controller and it alerts by giving continuous beep in case of abnormal conditions that may be related to unit or related to plurality of battery bank. A buzzer-reset circuit by pressing switch buzzer beep can be disabled manually and auto buzzer disable feature is also provided after a specific interval of time.
Fig 2 shows main controller 2 and in-circuit program section 9. It receives various analog/digital inputs from various sections of the circuit, and processes the received data to take the necessary actions. It displays & stores the corresponding data and declares the status of the various batteries. The controller 2 ensures that no procedure is skipped and it carries out all the functions in a predefined manner. The controller 2 also controls various sections like PWM driver 5, power transfer cum current protection section 3, display unit 11, communication unit 10, and buzzer section 12. The power to the controller 2 is supplied through a regulator. The controller 2 has internal reset circuitry and oscillator. Depending upon the requirement, either this internal oscillator or an external oscillator can be used to generate the clock. An In-circuit program port is provided to program or upgrade the embedded software in the controller 2 as per need.
Fig 3 shows Power/charge transfer cum current protection section. A numbers of power switches and capacitors are connected in series comprising a capacitor switch matrix. Power transfer circuit depicts plurality of serially connected power switches and capacitors to transfer power/charge from higher level battery to lower level battery. To attain this for example out of eight switches four power switches are turned ON at the
same time while other four power switches remain off as per table given below. ISW (current selection switch) turns ON when caarge transfer needs to be increased in case of large charge imbalance and remains OFF otherwise as per requirement along with power switch. The table shown below describes the alternate capacitor switching and increased charge transfer is achieved by properly selecting the switches:

(Table Removed)
ISW used to achieve which is to maintain maximum charge transfer between battery strings and to achieve boost charge transfer between batteries if charge unbalance between batteries is more. This alternate switching and Capacitor-Switch matrix is controlled by the main controller and operated at desired frequency.
By proper selection of switches, the capacitors connected can be provided in parallel to increase the power transfer by increasing the resultant capacitance. One set of switches and capacitors can be used alternately for power transfer.
Current protection in system is provided thiough glass fuses, these fuses are assembled in input/output wire harness for easy replacement of it in field. In place of glass fuse we can also use auto fuse, resettable fuse, electronic switch and even miniature circuit breakers.
Fig. 4 shows another power transfer Capacitor-Switch matrix

(Table Removed)
As per the present invention above table shows Capacitor-Switch matrix that facilitates boost and buck power transfer scheme so as to transfer charge/power between unbalanced serially connected battery strings.
As shown in above table four more ISW are added in previous circuit to achieve buck power transfer scheme also. For achieving buck power transfer, four power switch and three additional ISW will remain ON at same time and other four power switch along with six ISW will remain OFF at that time. Therefore, alternate switching of each set of power switch will be done along with ON ntate of three additional ISW and OFF state of other six ISW. (In this scheme out of 17 switches 7 will be on at a time).
Fig 5 shows the communication interface section each unit has two ports for input receiving and output transmit the data messages from one equalizer unit to another. It enables to communicate the any number of battery equalizer together so that the parameters measured for all the batteries 1 can be visualized at any time and in any one of the equalizer units. Remote monitoring is possible through serial port regarding connected individual battery voltage and temperature status. The communication is fully isolated with the help of opto-couplers. Each unit has an address selection switch section 15 with which any unit can be assigned an address. The master unit sends command to other units with their respective addresses and only that unit responds to the command which is having same address as in the command. The unit sends the voltages, temperature and current system status to the master unit. The master unit obtains all the information this way. The master unit also communicates to the battery charger through the communication interface to provide timely feedback on charge current adjustments.
Fig 6 shows the battery desulphator circuit in this energy stored in inductor capacitor combination 20 is used to generate high peak currents pulses of short duration to desulphate the ions hardening from plate, when gate pulses are required to do so is decided by controller. An isolated driver section is used to drive the desulphator circuit.
Via the aforementioned structure, each individual cell of the charging battery set can be appropriately charged in equalization, which not only increase the charging/discharging times of the battery set, but also efficiently extends the battery life in application. Multiple modules can be used, for example, in combination with multiple batteries which are coupled in series to one another. All the modules are connected through communication port so that the data of all the modules can be saved in each module. Thus, the status of all the modules can be viewed from any module.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims: -

WE CLAIM:
1. A battery charge equalizer connected to a plurality of batteries in series comprising of a control unit signaling a plurality of switches coupled to a number of capacitors, a current protection unit attached to the battery bank, a voltage/temperature sense unit and a battery desulphator circuit along with PWM driver controlled by said control unit driving isolated multiple gate output.
2. A battery charge equalizer as claimed in claim 1 wherein the multiple switch capacitors matrix is provided as charge transfer medium between the connected batteries.
3. A battery charge equalizer as claimed in claim 1 or 2 wherein said current protection unit provides high current protection to the system.
4. A battery equalizer as claimed in any of the preceding claims wherein said system can equalize any other charge storage device such as but not limited to double layer capacitor and can generate a signal for any external system such as battery charger, Inverter or UPS in case of any abnormal conditions such as high/low battery voltage, high current , high temperature or any other condition to stop charging of the system.
5. A signal generated as claimed in any of the preceding claims wherein the signal can also be used to operate any external switchgear.
6. A battery charge equalizer as claimed in any of the preceding claims wherein said isolated multiple gate drive output is connected to power transfer section, which is attached to the current protection unit so as to protect unit from high current.
7. A battery charge equalizer as claimed in any of the preceding claims wherein the voltage/temperature/current sense unit is attached to the battery bank, which senses the voltage, current and temperature rise in order to protect connected battery bank from abnormal conditions.
8. A battery charge equalizer as claimed in any of the preceding claims wherein multiple set of switches and capacitors matrix are provided in which switches and capacitors matrix increases the life of the capacitors used for charge transfer.
9. A battery charge equalizer as claimed in any of the preceding claims comprising of a communication interface section having connector to receive and transmit the data messages from one equalizer unit to another and to have inter unit communication for monitoring and control of a number of battery equalizer units connected to N number of batteries in series.
10. A battery charge equalizer as claimed in any of the preceding claims wherein multiple matrixes of switches and capacitors are provided to increase or decrease the charge transfer between the connected batteries and the communication interface could be a CAN bus, USB, RS-485 or a proprietary bus capable of communicating with each of the devices connected in a daisy chain fashion.
11. A battery charge equalizer as claimed in any of the preceding claims wherein the display unit is for example liquid crystal display, light emitting diodes or any other display device.
12. A battery charge equalizer as claimed in any of the preceding claims wherein multiple modules can be used, in combination with multiple batteries, which are coupled to one another in series wherein all the modules are connected through communication port in which the data of all the modules can be saved in each module and the status of all the modules can be viewed from any module.
13. A battery charge equalizer as claimed in any of the preceding claims wherein audio/visual messages are generated to update user regarding battery bank status.
14. A battery charge equalizer connected to a plurality of batteries in series substantially as herein described with reference to the accompanying drawings.