KR20180129383A - Lithium iron phosphate battery charging system - Google Patents

Abstract

A lithium iron phosphate battery charging system includes a lithium iron phosphate battery including a positive electrode made of lithium iron phosphate, a battery cell for supplying a charging current to the lithium iron phosphate battery, and a lithium iron phosphate battery charger for controlling the charging current by detecting a charging amount of the lithium iron phosphate battery. Therefore, the full charge of the lithium iron phosphate battery can be efficiently performed for a short time without restriction of time and space.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a lithium iron phosphate battery charging system,

The present invention relates to a battery charging system, and more particularly, to a lithium iron phosphate battery charging system. Meanwhile, the present invention is applicable to the "Research and Development Higher Manpower Support Project (Engineering and System Advanced Track for Green Remodeling of Buildings)" of the "Korea Energy Technology Evaluation Institute" and the " The present invention relates to a battery charging system derived from solving the troublesome technique of Jungwoo Engineering Co., Ltd. under the support of "Development of a battery management system for an energy storage system incorporating a circuit".

Generally, the secondary battery includes a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, and a lithium ion polymer battery. Such a secondary battery is classified into a lithium-based battery and a nickel-hydrogen-based battery.

Lead-acid batteries are a type of secondary battery, and dilute sulfuric acid is used as the electrolyte. The anode is lead dioxide (PbO ₂ ) and the cathode is lead (Pb), but discharging leads to lead sulfate (PbSO ₄ ), and at the same time, the concentration of the electrolyte decreases. The lifetime of the lead-acid battery is represented by the number of times until the capacity is reduced to 90% of the initial capacity during repetition of discharge, and is usually 500 to 1,000 times.

A lithium-based lithium secondary battery (i.e., a lithium ion battery) is composed of two electrodes (anode and cathode) and an electrolyte as in the other secondary batteries. Generally, the anode of a lithium ion battery is made of lithium cobalt oxide and the cathode is made of carbon such as graphite. The interior of the lithium ion battery is filled with an electrolyte and the electrons are separated into separate membranes. Inside, positive-charged lithium ions come and go between the positive electrode and the negative electrode (for example, carbon material and lithium cobalt oxide), and electrons are negatively charged, so current flows along the direction in which the positively charged lithium ions move do.

In recent years, it has excellent safety and durability, high rate charge / discharge characteristics, high energy density and little harmful substances such as lead, cadmium, mercury, and chromium in the battery, and high concentration of sulfuric acid or potassium hydroxide Research and development of lithium iron phosphate batteries and their charging methods, which are not environment friendly batteries, are actively under development.

It is an object of the present invention to provide a lithium iron phosphate battery charging system for charging an efficient lithium iron phosphate battery.

It should be understood, however, that the present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the invention.

In order to accomplish one object of the present invention, a system for charging a lithium iron phosphate battery according to embodiments of the present invention includes a lithium iron phosphate battery, a battery cell for supplying a charging current to the lithium iron phosphate battery, And a lithium iron phosphate battery charger that detects the charge current and controls the charge current.

According to an embodiment of the present invention, the lithium iron phosphate battery charger includes a power supply unit for supplying electric power, a converter unit for controlling the voltage value of the electric power to supply the charging current to the battery cell, a driving unit for driving the converter unit, And a control unit for controlling an electrical connection between the converter unit and the battery cell and an electrical connection between the converter unit and the battery cell.

According to an embodiment of the present invention, the controller may control the charging current by sensing a charging voltage of the lithium iron phosphate battery connected to the battery cell.

According to an embodiment of the present invention, the lithium iron phosphate battery charger may further include a first switch electrically connecting the power unit and the converter unit, and a second switch electrically connecting the converter unit and the battery cell. .

According to an embodiment, when the charging voltage of the lithium iron phosphate battery exceeds a preset reference voltage, the controller may turn off the first switch and the second switch.

According to an embodiment, when the charging voltage of the lithium iron phosphate battery is lower than a predetermined reference voltage, the controller may turn on the first switch and the second switch.

According to an embodiment, the battery cell may include a plurality of sub battery cells connected to each other in series.

The lithium iron phosphate battery charging system according to embodiments of the present invention is advantageous in terms of safety, configuration, and high charge / discharge characteristics, and can be charged with environmentally friendly lithium iron phosphate batteries faster than other charging devices or battery charging systems , Weather, time, space, and the like. Therefore, full charge of the lithium iron phosphate battery 100 can be efficiently performed in a short period of time.

However, the effects of the present invention are not limited to the effects described above, and may be variously extended without departing from the spirit and scope of the present invention.

1 is a diagram illustrating a lithium iron phosphate battery charging system in accordance with embodiments of the present invention.
FIG. 2 is a view showing an example in which a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG. 1 is charged.
3 is a view showing an example of a charger dedicated to a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG.
FIG. 4 is a view showing an example of analysis of characteristics of a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG. 1; FIG.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

FIG. 1 is a view showing a system for charging a lithium iron phosphate battery according to an embodiment of the present invention, and FIG. 2 is a view illustrating an example in which a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG. 1 is charged .

Referring to FIGS. 1 and 2, the lithium iron phosphate battery charging system 10 may include a lithium iron phosphate battery 100, a battery cell 200, and a charger 300 for a lithium iron phosphate battery. The lithium iron phosphate battery 100 may be connected to the battery cell 200 to be connected thereto.

The lithium iron phosphate battery charging system 10 is a charging system developed specifically for the lithium iron phosphate battery 100. [ In particular, the lithium iron phosphate battery 100 may be a lithium phosphate (LFP) battery 100 having excellent safety, durability, high charge / discharge characteristics, and high energy density.

Battery performance can depend on the duration of its lifetime. For example, the service life of a battery can be defined as the estimated time it takes for the battery to drop to about 80% of its total energy capacity. For example, experimentally, the service life of a lead-acid battery (e.g., valve-regulated lea-acid) battery is about 3 years to about 6 years, It may take more than a decade. While there may still be a few more years before data on the actual service life of recently developed lithium iron phosphate batteries will be available, some lithium-ion batteries offer a decade-long warranty And can be applied to various fields such as a vehicle and a building.

The lithium iron phosphate battery 100 has an olivine structure composed of iron and phosphorus. Because of the structural stability of the olivine structure, lithium iron phosphate battery 100 is more stable than a layered cathode material such as lithium cobalt oxide (LCO) and has a discharge voltage of about 3.5 V, which is greatly different from conventional lithium cobalt oxide And the discharge capacity can also be used on the order of 150 mAh / g. That is, the lithium iron phosphate battery 100 eliminates expensive cobalt even when there is no significant loss in terms of energy density, and there is also a manufacturing cost reduction effect by using low cost easy-to-obtain iron instead of the conventional cathode material. It is an excellent battery. In addition, lithium iron phosphate (LiF) batteries are lithium-iron phosphate (LiFePO4) batteries used for the anode to solve the problems of ignition and explosion which are fatal defects of existing Li-Co and Li-Mn batteries . Also, the lithium iron phosphate battery 100 is an eco-friendly product containing no harmful heavy metals (Pb, Cd, Hg, etc.).

Also, since the lithium iron phosphate battery 100 has a high energy density, the occupied space and volume are much smaller than lead-acid batteries. This space savings can be particularly attractive for colocation data centers or data centers with high real estate costs. In addition, weight is also lighter than lead acid batteries, which is advantageous in terms of transportation cost.

The lithium iron phosphate battery 100 may include a cathode 101, an anode 102, and an electrolytic solution. A separator is formed to prevent a short circuit between the cathode 101 and the anode 102, and this space is filled with the electrolyte solution.

The cathode 101 may include a carbon-based material such as graphite. The anode 102 may comprise lithium iron phosphate (LiFePO ₄ ) which is an active material and has no risk of explosion.

In one embodiment, the lithium iron phosphate battery 100 may have a laminate shape, a cylindrical shape, a hexahedral shape, or the like.

2, charging of the lithium iron phosphate battery 100 is performed by connecting the cathode 101 and the anode 102 of the lithium iron phosphate battery 100 to a power source such as a system power source. For example, the lithium iron phosphate battery 100 may be connected to the positive and negative electrodes of the battery cell 300 connected to the charger 200, and may be charged. For example, carrier ions (lithium ions) may move from the anode 102 toward the cathode 101 and be inserted into the cathode 101. [ At the time of charging, the electrolytic solution is decomposed on the surface of the cathode 101, and capacity can be formed according to the formation of the decomposition products.

The lithium iron phosphate battery charger 200 can control the charge current magnitude and supply status by monitoring the degree of charge of the lithium iron phosphate battery 100. [ In one embodiment, the lithium iron phosphate battery charger 200 includes a power supply unit for supplying power, a converter unit for controlling the voltage value of the power to supply (300) the charging current to the battery cell 300, And a controller for controlling an electrical connection between the converter unit and the battery cell and an electrical connection between the converter unit and the battery cell. The configuration and operation of the lithium iron phosphate battery charger 200 will be described in detail with reference to FIG.

The battery cell 300 can supply the charging current to the lithium iron phosphate battery 100. That is, the lithium iron phosphate battery 100 may be charged or discharged by being mounted or connected to the battery cell 300. In one embodiment, the battery cell 300 may include a plurality of sub-battery cells connected in series with each other. The charging current may be charged in the sub battery cells to charge a plurality of lithium iron phosphate batteries.

Meanwhile, in one embodiment, the lithium iron phosphate battery charger 200 may sense the cell charging voltage of each of the sub battery cells, and may control the charging current based on the sensed charging voltage.

As described above, the lithium iron phosphate battery charging system 10 according to the embodiments of the present invention can efficiently and quickly charge the environmentally friendly and highly efficient lithium iron phosphate battery 100 without time and place restrictions.

For example, when a 240 A lithium iron phosphate battery 100 is charged using a 250 W capacity solar module, a charging time of about 12 hours is required theoretically without power loss. In addition, since the solar cell included in the solar module can generate electric power only during the daytime when the sun is floating, it may take more than two days of charging time and is somewhat inefficient in charging.

Further, rather than charging the iron phosphate battery 100 using a charger for a lead acid battery (a lead battery), a general battery charger, or a multipurpose charger, charging using a charger dedicated to a lithium iron phosphate battery results in full charge time and charging efficiency .

That is, when the lithium iron phosphate battery 100 is charged by using the lithium iron phosphate battery charging system 10 of the present invention, the full charge time can be reduced by about 1/6 of that in the case of using the solar battery module 100 , Weather, time and space. Therefore, full charge of the lithium iron phosphate battery 100 can be efficiently performed in a short period of time.

3 is a view showing an example of a charger dedicated to a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG.

3, the lithium iron phosphate battery charger 200 for charging / discharging the lithium iron phosphate battery 100 may include a power supply unit 220, a converter unit 240, and a control unit 260. The lithium iron phosphate battery charger 200 includes a first switch SW1 for electrically connecting the power source unit 220 and the converter unit 240 and a second switch SW2 for electrically connecting the converter unit 240 and the battery cell 300 2 switch SW2. The lithium iron phosphate battery charger 200 can charge the lithium iron phosphate battery by supplying the charging current to the battery cell 300. [

As the power supply unit 220, for example, a power supply circuit using a system power supply can be applied. However, this is an example, and the configuration of the power supply unit 220 is not limited thereto. For example, a device capable of supplying electric power in a noncontact manner using a power supply device or the like may be used.

The converter unit 240 may be connected to the power unit 220, the controller 260, and the battery cell 300. The converter unit 240 can control the charge current value during charging and discharging of the battery cell 300 by converting the voltage supplied from the power supply unit 220, for example.

In one embodiment, the converter section 240 may be implemented as a step-up / step-down converter. The step-up / step-down converter may include, for example, a switching regulator and a control circuit. The switching regulator may comprise an inductor and at least one switch. The step-up / down converter controls the at least one switch by the control circuit so that the input voltage can be stepped up or stepped down and the value of the stepped up or stepped down voltage can be controlled. At the same time, the step-up / step-down converter can switch the direction of the current flowing in the inductor to switch the input and the output, thereby switching the charging and discharging of the battery cell 300. However, this is an example, and the control unit 260 may control the switch of the switching regulator instead of the control circuit.

In one embodiment, the step-up / step-down type converter may be implemented as a Single Ended Primary Inductor Converter (SEPIC) type converter or a Zeta type converter.

The control unit 260 may be connected to the battery cell 300, the power supply unit 220, and the converter unit 240. In one embodiment, the controller 260 may receive the voltage or current from the battery cell 300 and / or the power supply 220 to sense the voltage or current.

The controller 260 may control the value of the output voltage of the converter 240 by generating and outputting a command signal indicating the state of the converter 240. [ In addition, the control unit 260 may control the direction of the current flowing in the inductor of the converter unit 240 to control whether the battery cell 300 is charged or discharged.

In addition, the controller 260 may control on / off of the first and second switches SW1 and SW2 according to charge and discharge.

In one embodiment, when the charging voltage of the lithium iron phosphate battery exceeds a preset reference voltage, the controller 260 may turn off the first switch SW1 and the second switch SW2. Here, the reference voltage may be a value set to a full charge voltage of a lithium iron phosphate battery, for example. That is, when the charging voltage is detected to exceed the reference voltage, the lithium iron phosphate battery is determined to be fully charged and the first and second switches SW1 and SW2 may be turned off.

In one embodiment, when the charging voltage of the lithium iron phosphate battery is lower than the reference voltage, the controller 260 may turn on the first switch SW1 and the second switch SW2. That is, when the charging voltage is equal to or lower than the reference voltage, the first and second switches SW1 and SW2 may be maintained in a turned-on state to maintain the charging of the lithium iron phosphate battery.

In one embodiment, the control unit 260 may sense the charge voltage in the battery cell 300 and control the charge current (e.g., the output voltage of the converter unit 240).

In one embodiment, the controller 260 may be a microprocessor, a microprocessor unit (MPU), a micro control unit (MCU), a field programmable gate array (FPGA) a central processing unit (CPU), or a battery management unit (BMU).

The first switch SW1 is connected between the power supply unit 220 and the converter unit 240 to control the conduction between the power supply unit 220 and the converter unit 240. The second switch SW2 is connected to the converter unit 240, And the battery cell 300 to control the conduction between the converter unit 240 and the battery cell 300.

In one embodiment, the first switch SW1 and the second switch SW2 may include a transistor or a diode. For example, the first switch SW1 and the second switch SW2 may be implemented with a metal oxide semiconductor (MOS) thin film transistor. However, this is merely an example, and the configurations of the first switch SW1 and the second switch SW2 are not limited thereto.

The first switch SW1 and the second switch SW2 have a turned-on state during the charging period and the positive electrodes of the power supply unit 220 and the converter unit 240 and the battery cell 300 can be electrically connected . Accordingly, the charging current flows from the power source unit 220 to the battery cell 300 through the converter unit 240, and the battery cell 300 (i.e., the lithium iron phosphate battery) can be charged.

In the discharge period, one switch SW1 and the second switch SW2 are turned off, and the lithium iron phosphate battery can be discharged.

FIG. 4 is a view showing an example of analysis of characteristics of a lithium iron phosphate battery included in the lithium iron phosphate battery charging system of FIG. 1; FIG.

As shown in FIG. 4, the charging and discharging characteristics of a lithium-based batteries, that is, a lithium cobalt oxide (LCO) battery, a nickel cobalt manganese (NCM) battery, a nickel cobalt aluminum (NCA) battery, and a lithium iron phosphate have.

Lithium cobalt oxide (LCO) batteries, nickel cobalt manganese (NCM) batteries and nickel cobalt aluminum (NCA) batteries have high energy density and are easy to manufacture large capacity batteries. However, LFP) batteries.

The lithium iron phosphate battery of the present invention has a lower standard charging voltage and standard discharge voltage than other lithium series batteries, but has a capacity similar to that of a lithium cobalt oxide battery and has characteristics such as life characteristics, storage characteristics, safety, It also has a much cheaper advantage. Therefore, the lithium iron phosphate battery can be applied to a more relaxed transportation regulation and storage regulation than the lithium cobalt oxide (LCO) battery, the nickel cobalt manganese (NCM) battery and the nickel cobalt aluminum (NCA) battery.

Therefore, the lithium iron phosphate battery can be easily applied to various industrial fields, and can be widely used for transportation of industrial buildings, vehicles, and the like. At this time, the charging and discharging of the lithium iron phosphate battery is performed through the charger for the lithium iron phosphate battery of the present invention, thereby shortening the charging time and increasing the charging efficiency.

The present invention can be applied to a charging system for charging a lithium iron phosphate battery, a charging device, and a charging method.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

10: portable terminal 100: lithium iron phosphate battery
200: lithium iron phosphate battery charger 220: power source part
240: converter section 260: control section
300: battery cell

Claims (7)

A lithium iron phosphate battery including a positive electrode made of lithium iron phosphate;
A battery cell for supplying a charging current to the lithium iron phosphate battery; And
And a lithium iron phosphate battery charger that detects the charged amount of the lithium iron phosphate battery and controls the charging current. The lithium iron phosphate battery charger of claim 1, wherein the lithium iron phosphate battery charger
A power supply unit for supplying power;
A converter unit for controlling the voltage value of the power to supply the charging current to the battery cell; And
And a control unit for controlling the operation of the converter unit, the electrical connection between the power source unit and the converter unit, and the electrical connection between the converter unit and the battery cell. 3. The system of claim 2, wherein the controller controls the charging current by sensing a charging voltage of the lithium iron phosphate battery connected to the battery cell. The lithium iron phosphate battery charger of claim 3, wherein the lithium iron phosphate battery charger
A first switch for electrically connecting the power supply unit and the converter unit; And
And a second switch electrically connecting the converter unit to the battery cell. The lithium iron phosphate battery charging system according to claim 4, wherein when the charging voltage of the lithium iron phosphate battery exceeds a predetermined reference voltage, the control unit turns off the first switch and the second switch . 6. The system of claim 5, wherein when the charging voltage of the lithium iron phosphate battery is lower than a predetermined reference voltage, the controller turns on the first switch and the second switch. The system of claim 1, wherein the battery cell comprises a plurality of sub-battery cells connected in series with each other.

Images