WO2010018597A2 - Procédé et appareil pour l'égalisation de blocs-batteries - Google Patents

Procédé et appareil pour l'égalisation de blocs-batteries Download PDF

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Publication number
WO2010018597A2
WO2010018597A2 PCT/IN2009/000418 IN2009000418W WO2010018597A2 WO 2010018597 A2 WO2010018597 A2 WO 2010018597A2 IN 2009000418 W IN2009000418 W IN 2009000418W WO 2010018597 A2 WO2010018597 A2 WO 2010018597A2
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WO
WIPO (PCT)
Prior art keywords
battery pack
cells
voltage
equalizing
battery
Prior art date
Application number
PCT/IN2009/000418
Other languages
English (en)
Other versions
WO2010018597A3 (fr
Inventor
Lokesh Thawani
Original Assignee
Kpit Cummins Infosystems Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kpit Cummins Infosystems Limited filed Critical Kpit Cummins Infosystems Limited
Publication of WO2010018597A2 publication Critical patent/WO2010018597A2/fr
Publication of WO2010018597A3 publication Critical patent/WO2010018597A3/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014—Circuits for equalisation of charge between batteries
    • H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the present invention relates to the field of battery charging and more particularly to circuits for equalization of battery packs.
  • Batteries are used as power sources in a variety of applications ranging from laptops, mobile phones, cameras, and more recently, electric and electric-hybrid vehicles.
  • the utility value of these battery packs is decided by factors depending on their charging and discharging characteristics. It is often observed that individual cells / batteries within the same battery power system charge and discharge at different rates due to factors including different temperatures and the like. Thus, the capacities of individual batteries vary over time. This results in sub ⁇ ptimal performance and reduction in life of the battery system. At times it can result in explosion of the battery as well.
  • battery packs consisting of several NiMH or NiCd batteries connected in series to provide a 50-400V D.C. power source are most popularly the ones used in electric and hybrid electric vehicles.
  • the individual batteries in such battery packs differ in their charge / discharge characteristics. Lithium ion batteries in particular, are damaged in the occurrence of even slight over-voltages and/or heat built up in such circumstances. While charging of such battery systems, it is difficult to charge the entire individual serially connected cells to the same potential without applying over voltage. As mentioned earlier, even slight excess voltage is detrimental in case of lithium ion batteries.
  • a common method of equalization of battery packs that finds mention in the art is to simply allow the batteries to trickle charge for a few hours after the bulk charge is complete. This low current increases the charge in the undercharged, low voltage batteries without causing excessive heating in the fully charged, high voltage batteries.
  • This equalizing method is effective, but it requires an excessive charge time and thus fails to effectively address the said problems of the art. Additionally, such simple methods can be employed only for equalization of lead-acid battery packs or NiMH (Nickel metal hydride) battery packs. The over voltages generated herein are well sustained only by these types of battery packs. However, in the case of lithium ion batteries, over voltages of even brief duration can damage the batteries. Totally safe and yet efficient systems for equalization of lithium ion batteries have not been anticipated or stated by prior art.
  • Another method of cell equalization is passive balancing, a dissipative type technique, wherein the system functions to find the high-energy cells in the pack, and removes excess energy through a resistive element until their charges match the low cells.
  • Some other passive balancing schemes stop charging altogether when the first cell is fully charged, then discharge the fully charged cells into a load until they reach the same charge level as the weaker cells.
  • Still other schemes are designed continue charging till all the cells are fully charged but to limit the voltage which can be applied to individual cells and to bypass the cells when this voltage has been reached.
  • the charging of each individual cell is not parallel and hence, consumes time in proportion with the number of individual batteries attached serially. This method thus, does not answer the problems of art.
  • Another method of cell equalization is charge limiting. This method functions by simply switching off the charger when the first cell reaches the voltage which represents its fully charged state and to disconnect the battery when the lowest cell voltage reaches its cut off point of 2 Volts during discharging. This, unfortunately, terminates the charging before all of the cells have reached their full charge or cut off the power prematurely during discharge leaving unused capacity in the good cells. It thus reduces the effective capacity of the battery.
  • US 5,594,320 discloses an equalizer for equalizing the charge on several series-connected cells includes a transformer having plural windings on a core corresponding to the number of cells. The windings are tightly coupled to one another. A switching device such as a MOSFET is connected to each of the windings, and a winding and a switching device are connected across each of the cells. The switching devices are simultaneously switched at a relatively high frequency and the voltage across the highest charged cell appears across each of the windings when the switching devices are on.
  • a switching device such as a MOSFET is connected to each of the windings, and a winding and a switching device are connected across each of the cells. The switching devices are simultaneously switched at a relatively high frequency and the voltage across the highest charged cell appears across each of the windings when the switching devices are on.
  • a source voltage provided by the DC source may preferably be adjusted during the course of charge equalization to preferentially direct charge to weaker cells.
  • equalization of battery is done by drawing energy from the battery pack in which that cell is located. This leads to discharging and hence aging of the batteries.
  • US 6400124 discloses a battery charger for charging a plurality of battery cells connected in series with one another with a constant current in a batch manner.
  • the battery charger includes plurality of cell shunt circuit sections connected in parallel with the battery cells, a plurality of cell voltage detecting sections for detecting cell voltages of the battery cell, a cell shunt driving unit for driving the cell shunt circuit sections, an energy reservoir acting as a bypass path for bypassing a charging current supplied to a corresponding one of the battery cells and a switching element inserted in the bypass path for opening and closing thereof.
  • the cited art also refers to a charger for lithium-ion battery. This charger ensures that all the batteries are charged to their maximum potential.
  • the limitations of the cited prior art is that the it is for charging a battery system and not equalizing it whereas the present invention is for charging the individual cell and for equalizing the battery pack. Further, the goal of the inventor of the cited prior art is to regulate the current flowing into each cell. The excess current is fed back to the source using the transformer, transistor and the operational amplifiers. All the circuitry is used just to feed back the excess current whereas in present invention no excess current is present. Only the batteries which are a lower potential are brought up using an extra battery.
  • US 5717578 discloses an improved battery charging circuit that provides a substantially constant current output to a rechargeable battery.
  • constant current is provided on the front end of the battery charging circuit so that a current regulator need not be provided at the output of the transformer circuit used to convert the input voltage level into an appropriate output voltage level.
  • the circuit comprises a voltage input terminal which receives the voltage input; an output terminal which provides the supply current output; a current generation circuit which receives the voltage input via the voltage input terminal and outputs the supply current to the output terminal; and a feedback control circuit in communication with the current generation circuit so as to provide a feedback input signal to the current generation circuit in order to maintain a substantially constant value of the supply current output.
  • a problem with this system is that it is used to charge the entire battery pack not the individual cells of the pack. While charging entire pack, there are variations in charging that lead to imbalance and hence cause aging of the batteries. In addition, it uses a feedback circuit to maintain a constant value of the supply current output which makes the circuit more complex and expensive.
  • the present inventors have come up with novel electronic circuitry that can be used for equalization of lithium ion, other similar batteries or ultra capacitors and the like.
  • the present invention provides an apparatus and method for achieving the equalization of battery pack the use of which introduces various advantages including reduction in risk of damage to energy cells connected in the series in the battery pack and increased life of the battery.
  • the method of charge equalization of the battery pack employs an apparatus for equalization of battery pack.
  • Energy cells in the battery pack are individually equalized via a novel circuitry comprising of comparators, subtracters, switches, a microcontroller, a potential divider and the like.
  • the novelty of the present invention lies in the fact that components of the said apparatus perform synergistically to route current drawn from an auxiliary energy source to individual energy cells to result in their charge equalization.
  • Another fact that signifies the novelty of the present invention is that the routing of equalizing current is selective towards energy cells having voltage below a threshold voltage level and that the routing is stopped once the energy cells reach the threshold voltage level.
  • It is yet another object of the present invention provide a simple and low cost apparatus and method to equalize the battery pack.
  • FIG. 1 is a circuit diagram for schematic representation of the apparatus for equalization of battery packs in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION
  • FIG. 1 illustrates the apparatus for equalization of battery pack in accordance with the present invention.
  • the apparatus (O) comprises plurality of energy cells (B 1 , B 2 , B 3 .... B n ) arranged in series to form the battery pack.
  • the apparatus (O) further comprises a transformer consisting of a primary winding (A 0 ) and secondary windings (A 1 , A 2 , A 3 ....A n ) in connection with each of the energy cells of the battery pack, an energy source (B 0 ), switches (S1 and S2), a plurality of comparators (C 1 , C 2 , C 3 ....
  • decision as to draw current from the auxiliary battery and routing it to individual energy cell is taken on basis of charge levels of corresponding energy cell in the battery pack.
  • the charge level of each energy cell is determined, not as an individual measure, but an average value determined at a common junction point of the potential divider.
  • inputs of comparators (D 1 , D 2 , D 3 ....D n ) are connected to the common junction point (J) and resistances of the potential divider are chosen according to the number of energy cells in the battery pack .
  • r1 and r2 are values of resistances R1 and R2 comprising the potential divider Vj is the potential difference at the point (J) of the potential divider and V is the total voltage of the battery pack
  • the method of equalization of battery packs in accordance with the principles of the present invention comprises connecting the auxiliary energy source (A 0 ) across the primary winding of the transformer and inducing an equalizing current to be delivered selectively to the energy cells of the battery pack which are below desired voltage levels.
  • Selective routing of the equalizing current for a definite period without resulting in overcharging or heat buildup is made possible via the combined effect of comparators (C 1 , C 2 , C 3 .... C n ; D 1 , D 2 , D 3 ....D n ) and switches (S1 and S2) connected according to the circuit layout represented in Fig. 1.
  • Equalizing current is caused to be drawn from the auxiliary energy source in the case voltage induced in an energy cell is less than the average voltage determined at point (J).
  • This discriminatory function is possible as comparators (D 1 , D 2 , D 3 .... D n ) receive one input signifying reference voltage determined across point (J) of the potential divider and the other input of actual voltage of the corresponding energy ceil.
  • comparators (C 1 , C 2 , C 3 ....C n ) that receive inputs of voltages from both terminals of the energy cell and thereby give an output of the actual voltage of the particular energy cell to comparators (D 1 , D 2 , D 3 ....D n ).
  • the comparators (C 1 , C 2 , C 3 ....C n ) actually function as subtracters.
  • the comparators (D 1 , D 2 , D 3 ....D n ) give output to the switching devices (E 1 , E 2 , E 3 ....E n ) that allow for unidirectional flow of current.
  • the switching devices are MOSFETs, the gate terminals of which consist of the outputs of comparators (D 1 , D 2 , and D3....D n ).
  • the drain terminals and source terminals of these MOSFETs are connected with the secondary winding and the energy cells to effect in switching function to enable logical flow of current in accordance with the logic of the present invention.
  • Comparators for causing this effect can be selected from the group comprising of differential amplifiers, operational amplifiers and the like.
  • the switching devices can be selected from the group comprising of BJT, FET, MOSFETs, diodes, relays, UJTs and the iike.
  • the selective switching of the equalizing current is enabled via synchronized actuation of two switches S1 and S2.
  • S1 is connected across primary winding wherein it controls flow of equalizing current from primary to the secondary.
  • Switch S2 is connected across the potential divider such its activation brings the potential divider into circuit.
  • the purpose of the potential divider is to provide the average voltage of the entire battery pack.
  • ADC Analogue to Digital Converter
  • DAC Digital to Analogue Converter
  • a common art microcontroller may be used to read the voltage using the ADC. This voltage, divided by the number of energy cells in the battery pack gives the average voltage using DAC. Synchronization of the said switching devices is enabled by use of a common art microcontroller or discrete logic.
  • the switches S1 and S2 are switched ON or OFF simultaneously. As explained earlier, this switching can be either controlled through a microcontroller or using a discrete logic. The basic principle in either the case remains the same. The main intention is to switch on the switch S1 and S2 for the time sufficient enough to induce a voltage in the secondary which is equal to the voltage at the junction of R1 and R2. When S1 is switched OFF there is a voltage drop in the secondary coil. If the Switching Device is ON ⁇ voltage at the potential divider is greater than the battery voltage) at this point of time the +ve and -ve terminals of the batteries will short. To avoid this short it is crucial that S2 be switched simultaneously with S1.
  • the control logic uses the following rhetorics:
  • Selective routing of the equalizing current to energy cells is enabled via switching devices such as MOSFETs connected across the said energy cells. As long as the MOSFET is switched on, equalizing current flows into the energy cell, thereby recharging it. Once the voltage induced in the energy cell equals the voltage at common junction point (J), the MOSFET gets automatically turned OFF due to the comparator action, thereby breaking the supply of equalizing current and hence, avoiding damage to the energy cell by overcharging or heat buildup.
  • switching devices such as MOSFETs connected across the said energy cells.
  • An advantage of the present invention is that the size of the primary winding used is very small as compared to other transformer based methods for equalization of battery packs.
  • the reduction in size of the primary makes the circuit simple and saves on weight and construction costs.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

L'invention concerne un appareil et un procédé qui permettent de charger des éléments de batterie et d'égaliser le bloc-batterie. L'appareil précité comprend, entre autres, un transformateur comportant un unique enroulement primaire, un second enroulement primaire relié à chacun des éléments de batterie précités et, reliée à l'enroulement primaire, une source d'énergie qui fournit l'énergie d'égalisation. Le flux du signal de charge est automatiquement régulé par le biais des circuits selon l'invention. Le système d'égalisation de charge selon l'invention permet d'égaliser des éléments individuels dans un système de batterie sans devoir extraire de l'énergie des autres éléments du même bloc-batterie, et sans entraîner de surchauffe ni endommager la batterie.
PCT/IN2009/000418 2008-07-28 2009-07-23 Procédé et appareil pour l'égalisation de blocs-batteries WO2010018597A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN1599MU2008 2008-07-28
IN1599/MUM/2008 2008-07-28

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Publication Number Publication Date
WO2010018597A2 true WO2010018597A2 (fr) 2010-02-18
WO2010018597A3 WO2010018597A3 (fr) 2010-04-22

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102364812A (zh) * 2011-10-28 2012-02-29 中国兵器工业集团第二一四研究所苏州研发中心 一种动力电池组充电均衡电路
CN106602615A (zh) * 2015-10-14 2017-04-26 山东鲁能智能技术有限公司 一种电池组主动均衡级联系统及均衡方法
DE102016212568A1 (de) * 2016-07-11 2018-01-11 Robert Bosch Gmbh Batteriesystem mit einer Batterie zum Einspeisen von elektrischer Energie in ein erstes Spannungsnetz und ein zweites Spannungsnetz
CN109120251A (zh) * 2017-06-22 2019-01-01 付允念 一种串联电池组电池管理系统的mos开关驱动电路及其阵列
CN112583084A (zh) * 2020-12-25 2021-03-30 河北工业大学 基于电容和导电膜的动力电池均衡与加热复合电路

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5594320A (en) * 1994-09-09 1997-01-14 Rayovac Corporation Charge equalization of series connected cells or batteries
US6150795A (en) * 1999-11-05 2000-11-21 Power Designers, Llc Modular battery charge equalizers and method of control
US6373223B1 (en) * 2000-11-21 2002-04-16 Nagano Japan Radio Co., Ltd. Voltage equalizing apparatus and voltage equalizing method for battery devices
US7061207B2 (en) * 2002-08-09 2006-06-13 H2Eye (International ) Limited Cell equalizing circuit
US7352154B2 (en) * 2004-01-14 2008-04-01 Vanner, Inc. Electrical system control for a vehicle

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5594320A (en) * 1994-09-09 1997-01-14 Rayovac Corporation Charge equalization of series connected cells or batteries
US6150795A (en) * 1999-11-05 2000-11-21 Power Designers, Llc Modular battery charge equalizers and method of control
US6373223B1 (en) * 2000-11-21 2002-04-16 Nagano Japan Radio Co., Ltd. Voltage equalizing apparatus and voltage equalizing method for battery devices
US7061207B2 (en) * 2002-08-09 2006-06-13 H2Eye (International ) Limited Cell equalizing circuit
US7352154B2 (en) * 2004-01-14 2008-04-01 Vanner, Inc. Electrical system control for a vehicle

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102364812A (zh) * 2011-10-28 2012-02-29 中国兵器工业集团第二一四研究所苏州研发中心 一种动力电池组充电均衡电路
CN102364812B (zh) * 2011-10-28 2014-04-23 中国兵器工业集团第二一四研究所苏州研发中心 一种动力电池组充电均衡电路
CN106602615A (zh) * 2015-10-14 2017-04-26 山东鲁能智能技术有限公司 一种电池组主动均衡级联系统及均衡方法
CN106602615B (zh) * 2015-10-14 2023-09-01 山东鲁软数字科技有限公司智慧能源分公司 一种电池组主动均衡级联系统及均衡方法
DE102016212568A1 (de) * 2016-07-11 2018-01-11 Robert Bosch Gmbh Batteriesystem mit einer Batterie zum Einspeisen von elektrischer Energie in ein erstes Spannungsnetz und ein zweites Spannungsnetz
CN109120251A (zh) * 2017-06-22 2019-01-01 付允念 一种串联电池组电池管理系统的mos开关驱动电路及其阵列
CN112583084A (zh) * 2020-12-25 2021-03-30 河北工业大学 基于电容和导电膜的动力电池均衡与加热复合电路
CN112583084B (zh) * 2020-12-25 2024-04-12 河北工业大学 基于电容和导电膜的动力电池均衡与加热复合电路

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