KR20160007899A - Power System for Over-Charge of Battery Pack And Device Having the Same - Google Patents

Abstract

The present invention provides a power system which comprises: a battery pack including at least two unit cells; an external power supply for receiving power of the battery pack or supplying power to the battery pack; a power relay assembly (PRA) for blocking or permitting a current inputted and outputted to and from the battery pack; and a battery management system (BMS) for managing and controlling voltage, temperature, and/or capacity of the battery pack. The PRA includes: a voltage measuring device for measuring each voltage of the unit cells contained in the battery pack; and first, second, and third relay units which are combined to block the circuit when one or more unit cells are over-charged in the battery pack. The first, second, and third units block a current transmitted to the battery pack when one or more battery cells are charged with a voltage which exceeds 4.5 V.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power system for preventing overcharge of a battery pack,

The present invention relates to a power supply system for preventing overcharging of a battery pack and a device including the same.

BACKGROUND ART Hybrid electric vehicles (HEVs) are vehicles that use a motor using an internal combustion engine and an electric power source of a battery as a power source. The hybrid electric vehicle (HEV) has received much attention as a next-generation transportation means due to depletion of fossil fuels.

The hybrid electric vehicle runs from the high speed running to the internal combustion engine and stores the kinetic energy due to the extra driving force or the braking at this time, and runs from the low speed running to the motor through the stored battery power.

Here, a lithium battery is mainly used as a battery used as a motor power source. The lithium battery includes a lithium-ion (Li-ion) battery using a liquid electrolyte and a lithium-polymer battery using a solid electrolyte polymer electrolyte.

In a hybrid electric vehicle, about 50 to 100 cells are connected in series according to the required capacity of the battery, and the hybrid vehicle is mounted on the vehicle in the form of a single pack.

Conventionally, each cell voltage is measured by a voltage measuring sensor included in the battery pack. When the voltage exceeds a reference voltage, a battery management system (BMS) issues an alarm message or a trip message, To the controller (HCU) side to stop the charging.

However, since the above method is a software method, when the communication of the vehicle is troublesome, the cell voltage is erroneously measured, and the battery is overcharged and exploded in the event of malfunction or malfunction of the battery management system (BMS) There was a problem.

To solve this problem, a power supply system as shown in Fig. 1 is applied to a hybrid vehicle. 1, the power supply system 10 includes a battery pack 20, a hybrid vehicle 60 as an external power source, a battery management system (BMS) 40, and a BMS 40, And two relay units 31 and 32 for interrupting or connecting the circuits of the vehicle 60. [

Here, the two main relay units 31 and 32 are electrically connected between the battery pack 20 and the vehicle 60 as an external power source, while the magnetic coils included in the relay unit are electrically connected to the BMS 40 It is composed of connected structure.

The relay units 31 and 32 are composed of a relay switch 33 and a magnetic coil 34. The operation principle of the relay units 33 and 32 is such that when a current flows through the magnetic coil 34, Is led by the magnetic coil 34 to close the circuit and thereby allow current to flow through the relay 33. [ On the other hand, when no current flows through the magnetic coil 34, a magnetic field is not formed in the magnetic coil 34, and the relay switch 33 is opened by itself to open the circuit, thereby preventing current from flowing.

When the battery pack is charged above the reference voltage, the HCU 50 senses this and sends the signal 52 to the BMS 40, and the BMS 40 receives the signal Power is supplied to the magnetic coil 33 of the relay units 31 and 32 so that the relay 33 included in the relay units 31 and 32 is opened and the battery pack 20 And the external power source 60 to prevent the battery pack 20 from being charged.

However, in this structure, when an error occurs in the signal between the HCU 50 and the BMS 40, the relay 33 of the relay units 31 and 32 is opened or closed regardless of the reference voltage, A safety problem of the battery pack 20 due to charging or overcharging of the battery pack 20 may be caused.

Therefore, in the hybrid electric vehicle, there is a great need for a technique that can effectively prevent overcharging of the battery pack 20.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments, and have found that, as will be described later, the relays, which are combined to block the circuit when one or more unit cells are overcharged in the battery pack, It is possible to prevent the battery pack from being overcharged and to improve the safety of the device using the battery pack and the battery pack. Thus, the present invention has been accomplished.

According to an aspect of the present invention, there is provided a power supply system including a battery pack including two or more unit cells;

An external power source that receives power from the battery pack or supplies power to the battery pack;

A PRA (Power Relay Assembly) for interrupting or allowing the current input / output to / from the battery pack; And

A BMS (Battery Management System) for managing and controlling voltage, temperature and / or capacity of the battery pack;

And,

The PRA includes a voltage meter for measuring the voltage of each of the unit cells included in the battery pack, a first relay unit and a second relay unit combined to block the circuit when at least one unit cell is overcharged in the battery pack, And a third relay unit, wherein the first relay unit, the second relay unit, and the third relay unit cut off a current to be transmitted to the battery pack when the at least one battery cell is charged with a voltage exceeding 4.5V.

That is, in addition to the BMS that can prevent overcharging of the battery pack, the battery system according to the present invention may also include a voltage measuring unit for measuring the voltage of each unit cell included in the battery pack, and a PRA including a plurality of relays, The overcharge of the battery cells can be prevented, and the overcharge of the battery pack can be effectively prevented.

In one specific example, the first relay unit, the second relay unit, and the third relay unit may each include a current coil and a relay.

The third relay unit may be a main relay disposed between the first relay unit and the second relay unit and the relay of the third relay unit may be a relay disposed between the current coils of the first relay unit and the current coils of the third relay unit. have.

The relay of the first relay unit may be electrically connected between the positive terminal of the battery pack and the positive input / output terminal of the external power source, and the current coil may be connected between the relay of the third relay unit and the input / output terminal of the BMS.

The relay of the second relay unit may be electrically connected between the negative terminal of the battery pack and the negative input / output terminal of the external power source, and the current coil may be connected to the input / output terminal of the BMS.

The relay of the third relay part may be connected between the current coil of the first relay part and the input / output terminal of the BMS, and the current coil may be connected to the voltage measuring device. Here, the voltage meter can cause the current to flow to the current coil of the third relay unit only when the voltage of the at least one unit cell measured exceeds 4.5V.

The current coil is a magnetic coil that generates a magnetic field when a current flows through the current coil. The relay is metallic so as to be led to correspond to the magnetic force of the current coil. The relay is in the form of a conductive switch bar Lt; / RTI >

Here, the first relay unit and the second relay unit may have a structure in which, when the current does not flow through the current coils, the relay is opened to block the current from flowing through the relay.

The first relay unit and the second relay unit are structured such that the relays of the first relay unit and the second relay unit can move up and down. The current coils are positioned at the upper or lower end of the relay, When no current flows through the coil, the relay moves to the opposite side of the current coil and is not in contact with the circuit. As a result, no current can flow through the relay. On the contrary, when a current flows in the current coil, the relay moves in the direction of the current coil and forms a contact with the circuit. As a result, current flows through the relay.

The third relay unit may further include a magnetic unit disposed adjacent to the current coil, the third relay unit including a further relay unit as compared with the first relay unit and the second relay unit.

Specifically, the relay of the third relay part is located between the current coil of the first relay part and the current coil of the third relay part, and is affected by the current coils of both relay parts. At this time, when a current equal to or higher than the reference voltage is supplied to the current coil of the third relay unit, the relay of the third relay unit moves in the direction of the current coil. At this time, So that the relay can be prevented from moving further in the direction of the current coil.

That is, when the current of 4.5 V or less, which is the reference voltage, flows in the current coil of the first relay unit, the third relay unit moves in the current coil direction of the first relay unit, closes the relay, And when a current exceeding 4.5 V flows through the current coil of the third relay part, the relay of the third relay part moves to the magnetic part and opens the relay so that the current through the relay of the third relay part To block the flow of gas.

When the voltage of one or more unit cells in the battery pack is charged to a voltage higher than 4.5 V, the third relay unit causes a current to flow from the voltage meter to the current coil of the third relay, The relay is moved to the magnetic part and is opened to block the current from flowing from the relay of the third relay to the current coil of the first relay part.

Therefore, the first relay unit is disconnected from the current coil of the first relay unit to open the relay, thereby preventing the current from flowing from the external power source to the battery pack, and preventing the battery cell from overcharging exceeding 4.5 V.

That is, the third relay part disposed between the first relay part and the second relay part has its current coil connected to the voltage measuring device of the PRA, and when the voltage measuring device detects that at least one of the cells of the battery pack is charged to 4.5 V or higher The relay of the third relay unit is disconnected, and the first relay unit can also be continuously disconnected.

As described above, since the respective current coil portions of the first relay portion and the second relay portion are connected to the BMS, it is possible to prevent the current from flowing to the current coils based on the voltage measurement value calculated by the BMS, The relay of the first relay part and the second relay part is opened to prevent the current from flowing from the external power source to the battery pack.

Therefore, in the power supply system according to the present invention, when the external power exceeds the reference voltage of 4.5 V in the course of charging the battery pack, the two blocking systems of BMS and PRA can independently block the charging of the battery pack And the effect of preventing overcharge is very excellent.

The external power source means an electric power generating element capable of supplying power from the outside to the battery pack for charging the battery pack. The external power source may be, for example, a battery pack charger or an external generator. As one example of the external generators, the generator may be a vehicle generator that converts kinetic energy resulting from driving or braking of the vehicle into electricity, but is not limited thereto.

In one specific example, the BMS may electrically connect the external voltage detecting means, the first relay portion, the second relay portion and the third relay portion, The BMS sends a blocking signal to the BMS so that current does not flow through the current coils of the first relay unit and the second relay unit and the relays of the first relay unit and the second relay unit are opened It may be a structure for blocking the charging of the battery pack.

The external voltage detecting means is electrically connected to the voltage measuring device of the PRA. When the voltage measuring device detects that the battery cells of the battery pack are charged to exceed 4.5 V, the voltage measuring device notifies the external voltage detecting means of the charging , The external voltage detecting means may determine the current and cause a current exceeding 4.5 V to flow through the current coil of the third relay unit to the voltage measuring unit to open the relay of the third relay unit.

The external voltage detecting means may be an HCU (Hybrid Control Unit). The HCU is a main computer of a vehicle, and is a device for controlling the overall running of the vehicle, and is a system for determining and controlling the power distribution of the vehicle, so that the HCU can determine whether to charge the battery pack.

The battery pack may include at least one battery cell, and the battery cell may include a lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte containing a lithium salt, Battery. Other configurations of the secondary battery will be described in detail below.

The positive electrode is prepared by applying an electrode mixture, which is a mixture of a positive electrode active material, a conductive material and a binder, on a positive electrode current collector, followed by drying. If necessary, a filler may be further added to the mixture.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with a transition metal; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like, but is not limited thereto.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The conductive material is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

On the other hand, a graphite-based material having elasticity can be used as a conductive material, and can be used together with these materials.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide and the like can be used, and in particular, a carbon-based material and / or Si can be included.

The negative electrode current collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and lithium. Nonaqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used as the nonaqueous electrolyte, but the present invention is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

The lithium salt-containing non-aqueous electrolyte may further contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. May be added. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing non-aqueous electrolyte.

The present invention also provides a mid- to large-sized device using the power system, which may be, for example, an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. These devices include an external power source that can charge the battery pack through the power system described above.

As described above, the power supply system according to the present invention includes a voltage measuring unit for measuring the voltage of each of the unit cells included in the battery pack, and a PRA including a plurality of relays, in addition to the BMS capable of preventing overcharge of the battery pack. In the process of charging the battery pack through the external power supply, when the reference voltage is higher than 4.5 V, two methods of BMS and PRA can independently block the charging of the battery pack, It has excellent effect.

1 is a schematic diagram showing a power supply system according to the prior art;
2 is a schematic diagram showing a power supply system according to the present invention;
FIG. 3 is a schematic view illustrating a state in which the battery pack is charged to a level higher than a reference voltage in the power supply system of FIG. 2; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

2 schematically shows a power supply system according to the present invention.

2, the power supply system 100 includes a battery pack 120, an external power source 160, a battery management system (BMS) 140, and a PRA 130 , Power Relay Assembly).

The external power supply 160 may be a power generator of the hybrid vehicle and is connected to the HCU 150 (Hybrid Control Unit) as an external voltage detecting means. The HCU 150 is a main computer of the hybrid vehicle and the HCU 150 determines whether or not the battery pack 120 is charged and transmits it to the BMS 140 in communication with the BMS 140. The BMS 140 This is done. Therefore, the generator, which is the external power source 160, can convert kinetic energy resulting from driving or braking of the hybrid vehicle into electricity and charge the battery pack 120 at about 4.5 V or less. ). That is, the HCU 150 determines the charging voltage, the capacity of the battery pack 120, the driving state of the vehicle, and the like, and determines whether to charge or stop charging the battery pack 120.

The PRA 130 includes a voltage meter 134, a first relay unit 131, a second relay unit 132, and a third relay unit 133. The third relay unit 133 is located between the first relay unit 131 and the second relay unit 132.

The first relay unit 131 includes a relay 131a and a current coil 131b located at the lower end of the relay and including a magnetic coil. The second relay unit 132 includes a relay 132a and a current coil 131b located at the lower end of the relay and including a magnetic coil. The third relay unit 133 includes a relay 133a and a current coil 133b located at the lower end of the relay and including a magnetic coil and a magnetic part 133c between the relay 133a and the current coil 133b .

The relay 131a of the first relay unit 131 is electrically connected between the positive terminal of the battery pack 120 and the terminal of the external power source. The second relay unit 132 is electrically connected between the negative terminal of the battery pack 120 and another terminal of the external power source. The relay 133a of the third relay unit 133 is electrically connected between the current coil 131b of the first relay unit 131 and the BMS 140 and the electrical connection with the BMS 140 is electrically connected to the BMS 140 And is electrically connected to the HCU 150 via the connection terminal (not shown).

The current coil 131b of the first relay unit 131 is electrically connected between the relay 133a of the third relay unit 133 and the BMS 140 via the BMS 140 And is electrically connected to the HCU 150. The current coil 132b of the second relay unit 132 is electrically connected to the BMS 140 and the electrical connection is electrically connected to the HCU 150 via the BMS 140. The current coil 133b of the third relay unit 133 is electrically connected to the voltage measuring unit 134 and a part of the current coil 133b connected to the voltage measuring unit 134 is electrically connected to the HCU 150 .

The HCU 150 includes an auxiliary battery (not shown) of 12 V or more and is connected to the first relay unit 131 via the BMS 140 or the voltage measuring unit 134 with the power of the auxiliary battery of the HCU 150. [ 132b, and 133b of the first relay unit 132, the second relay unit 132, and the third relay unit 133, respectively.

The voltage meter 134 is electrically connected to the battery cells 121 included in the battery pack 120 and detects the voltages thereof. At this time, when the battery cells 121 of the battery pack 120 are charged from the external power supply 160 at a voltage of 4.5 V or less, the voltage meter 134 supplies the current from the battery of the HCU 150 to the third relay unit To the current coil 133b of the current mirror 133. The relay 133a of the third relay unit 133 is energized by closing the circuit and is electrically connected to the current coil 131b of the first relay unit 131. [ At the same time, when the charging voltage of the battery pack 120 is 4.5 V or less, the HCU 150 and the BMS 140 supply the current from the battery of the HCU 150 to the first relay unit 131 and the second relay unit 131, The current coils 131b and 132b of the second relay unit 132 are caused to flow through the current coils 131b and 132b and the current coils 131b and 132b have the magnetic force The relays 131a and 132a move to the vicinity of the current coils 131b and 132b and the circuit between the battery pack 120 and the external power source 160 is closed and energized.

Meanwhile, FIG. 3 is a schematic view illustrating a state in which the battery pack is charged in excess of 4.5 V as a reference voltage in the power supply system of FIG.

Referring to FIG. 3 together with FIG. 2, when the voltage of the battery cells 121 is charged to exceed 4.5 V, the voltage meter 134 detects a current generated in the battery of the HCU 150 from the third relay unit 133 'to the current coil 133b. At this time, the current coil 133b of the third relay unit 133 forms a magnetic field and moves the relay 133a of the third relay 133 to the vicinity of the current coil 133b by the magnetic force, Is fixed by the magnetic portion 133c formed near the current coil 133b. The relay 133a of the third relay unit 133 blocks the current coil 131b of the first relay unit 131 from being electrically connected to the BMS 140 and the HCU 150, The relay 131a of the first relay part 133b is opened and the electric connection between the battery pack 120 and the external power supply 160 is not performed because the current coil 131b of the battery 131 does not form a magnetic field. And prevents the battery pack 120 from being charged.

The HCU 150 may control the current coils of the first relay unit 131 and the second relay unit 132 via the BMS 140 when the battery pack 120 is overcharged by 4.5 V or more The relays 131a and 132a move in the opposite directions of the current coils 131b and 132b so that the battery pack 120 and the external power source 160 Disconnect the electrical connection.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (17)

A battery pack including two or more unit cells;
An external power source that receives power from the battery pack or supplies power to the battery pack;
A PRA (Power Relay Assembly) for interrupting or allowing the current input / output to / from the battery pack; And
A BMS (Battery Management System) for managing and controlling voltage, temperature and / or capacity of the battery pack;
And,
The PRA includes a voltage meter for measuring the voltage of each of the unit cells included in the battery pack, a first relay unit and a second relay unit combined to block the circuit when at least one unit cell is overcharged in the battery pack, Wherein the first relay unit, the second relay unit, and the third relay unit cut off a current to be transmitted to the battery pack when the at least one battery cell is charged with a voltage exceeding 4.5 V, system. The power system according to claim 1, wherein the first relay unit, the second relay unit, and the third relay unit each include a current coil and a relay. 3. The power supply system according to claim 2, wherein the first relay unit and the second relay unit are configured to open the relay when the current does not flow to the current coil, and to prevent the current from flowing through the relay. 3. The power system of claim 2, wherein the third relay further comprises a magnetic portion located adjacent to the current coil. The apparatus according to claim 2 or 4, wherein when the current of 4.5 V or less flows into the current coil of the first relay unit, the third relay unit closes the relay so that current flows through the relay of the third relay unit, The relay of the third relay part is moved to the magnetic part and the relay is opened so as to prevent the current from flowing through the relay of the third relay part when a current exceeding 4.5 V flows through the current coil of the third relay part, system. The relay of claim 2, wherein the relay of the first relay unit is electrically connected between the positive terminal of the battery pack and the positive input / output terminal of the external power supply, and the current coil is connected between the relay of the third relay unit and the input / The power supply system comprising: The power supply system according to claim 2, wherein the relay of the second relay unit is electrically connected between the negative terminal of the battery pack and the negative input / output terminal of the external power supply, and the current coil is connected to the input / . The power supply system of claim 2, wherein the relay of the third relay unit is connected between the current coil of the first relay unit and the input / output terminal of the BMS, and the current coil is connected to the voltage meter. 9. The power supply system of claim 8, wherein the voltage meter causes a current to flow to the current coil of the third relay unit only when the voltage of the at least one unit cell measured exceeds 4.5V. 6. The battery pack according to claim 5, wherein, when the voltage of at least one unit cell in the battery pack is charged to a voltage higher than 4.5 V, the third relay unit causes a current to flow from the voltage meter to the current coil of the third relay, And the relay of the third relay part is opened to the magnetic part so as to block the current from flowing from the relay of the third relay to the current coil of the first relay part. 11. The battery pack according to claim 10, wherein the first relay part has a current interrupted by a current coil thereof to open a relay and prevents current from flowing from the external power supply to the battery pack, thereby preventing the battery cell from overcharging exceeding 4.5 V ≪ / RTI > The power supply system according to claim 1, wherein the BMS electrically connects the external voltage detection means, the first relay unit, the second relay unit, and the third relay unit. 13. The battery pack according to claim 12, wherein the external voltage detecting means senses the at least one battery cell when it is charged to more than 4.5 V and sends a shutoff signal to the BMS, And the relay of the first relay unit and the relay of the second relay unit are opened to interrupt the charging of the battery pack. 14. The power supply system according to claim 13, wherein the external voltage detecting means is an HCU (Hybrid Control Unit). The battery pack according to claim 1, wherein the battery pack includes at least one battery cell. A medium and large-sized device using the power system according to claim 1. 17. The device of claim 16, wherein the medium to large device is an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

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