JP2017069160A - Charger and charging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger capable of supplying a power to a battery arranged by use of a novel positive electrode material while suppressing the rise in battery temperature or the increase in power consumption in charging the battery, and a charging method.SOLUTION: A battery 10 arranged by use of a novel positive electrode material has a feature such that the resistance is large in the case of a remaining capacity under a threshold of characteristic change, and the resistance in the case of a remaining capacity of 0% becomes twice or more the resistance in the case of a remaining capacity equal to or larger than the threshold of characteristic change. When the remaining capacity of the battery 10 is under the threshold of characteristic change, a control circuit 14 controls an auxiliary power supply 13 to supply a power from the auxiliary power supply 13 to the battery 10, and charges the battery 10 until the remaining capacity of the battery 10 reaches at least the threshold of characteristic change. Therefore, it is possible to avoid such an event that in the condition of a large resistance, a power is supplied from a motor 12 in a regeneration state to the battery 10 through power conversion circuit 11. Besides, in the case that the remaining capacity of the battery 10 is under the threshold of characteristic change, the battery 10 is charged by flowing a reserve charging current smaller than a normal charging current.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a battery charging device and a battery charging method.

  In recent years, with the widespread use of electric vehicles, demand for secondary batteries for driving the vehicles has been increasing. In these electric vehicles, in order to improve fuel efficiency and mountability, the secondary battery is expected to have a higher capacity and a smaller size, and the performance of the secondary battery is required to be improved. Among secondary batteries, non-aqueous electrolyte secondary batteries, in particular lithium ion batteries, can be increased in capacity, and thus are being used as power sources for driving various electric vehicles.

  A non-aqueous electrolyte secondary battery generally includes a positive electrode in which a positive electrode active material layer having a positive electrode material typified by a positive electrode active material is formed on the surface of a positive electrode current collector, and a negative electrode active material layer having a negative electrode active material. A negative electrode formed on the surface of the electric body is connected via a non-aqueous electrolyte and is housed in a case. In a lithium ion battery which is a typical example of a nonaqueous electrolyte secondary battery, a lithium composite oxide is used as a positive electrode material. For example, Patent Documents 1 to 6 describe lithium composite oxides that can be used as positive electrode materials.

Patent Document 1 describes that Li _x CoMO ₂ and LiNiMnMO ₂ are mixed to form a positive electrode active material. Here, M is a predetermined element. This positive electrode active material has an active material having a high average voltage during discharge and an active material having high thermal stability.

Patent Document 2 describes a positive electrode active material including a crystal layer having a layered rock salt structure of LiNiMnTiO ₂ . When this positive electrode active material contains Ti, a higher charge / discharge capacity can be obtained compared to the case where Ti is not contained.

Patent Document 3 describes that Li _x MnMO ₄ and LiNiMO ₂ are mixed to form a positive electrode active material. Here, M is a predetermined element. By using this positive electrode active material, the battery performance after high-temperature storage can be made excellent.

Patent Document 4 describes a positive electrode active material in which a part of Li in a layered polycrystalline LiMnMO ₂ is missing. Here, M is a predetermined element. This positive electrode active material is stabilized in strain and chemical bonds in the crystal, and can improve cycle stability, durability stability, and the like during charge and discharge.

Patent Document 5 describes a positive electrode active material in which Li and Co are partially substituted with a predetermined element M in LiCoO ₂ . In this positive electrode active material, each of Li and Co is replaced by the element M, whereby the bonding force between the lithium layer and the cobalt layer is strengthened, and the strain between the layers and the expansion of the crystal lattice are suppressed. Cycle stability, durability stability, etc. can be improved.

Patent Document 6 describes that LiNiMnCoO ₂ and Li ₂ MO ₃ are mixed to form a positive electrode active material. Here, M is a predetermined element. This positive electrode active material has an active material that exhibits an excellent effect on battery capacity and safety, and an active material that exhibits an effect on cycle characteristics and storage characteristics. However, none of these positive electrode active materials can sufficiently suppress the collapse of the crystal structure during charge / discharge, leading to a problem in that the capacity of the nonaqueous electrolyte secondary battery is reduced.

Further, Non-Patent Document 1 describes a technique of using a positive electrode containing Ti, that is, LiNiMnTiO ₂ for safety. However, as described in Non-Patent Document 1, it is described that an overwhelming improvement in safety cannot be obtained by addition of Ti.

In Non-Patent Document 2, as another attempt to achieve both safety and high crystal stabilization, a positive electrode containing Si having a strong binding force with oxygen in the same amount as a transition metal, that is, Li ₂ MnSiO ₄ and The technology to do is described. However, in this positive electrode, since the transition metal has a four-coordinate coordination structure, the structure becomes unstable at the time of charging, and it has not been possible to form a positive electrode having sufficient durability.

JP 2007-188703 A JP 2008-127233 A JP 2001-345101 A JP 2001-250551 A Japanese Patent No. 3782058 JP 2006-202702 A "Synthesis of LiNi0.5Mn0.5-xTixO2 by an Emulsion Drying Method and Effect of Ti on Structure and Electrochemical Properties, Vol. 27, Chemistry 25, Chemistry 24." “Li2MSiO4 (M = Fe and / or Mn) cathode materials”, Journal of Power Sources, 2008, 184, P462-P468.

In order to solve the above problems, the present inventors have focused on the structure of a positive electrode material, and have a six-coordinate structure as a local structure of a transition metal and a positive electrode material containing a large amount of an element that strongly binds to oxygen. As a result, the present inventors have found that the above problems can be solved. This new positive electrode material has a layered rock salt type crystal structure, a transition metal has a local structure of 6-coordination, and is represented by the chemical formula Li _2-x Ni _α M ¹ _β M ² γO _4-ε. Contains transition metal oxides. Here, 0.50 <α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, and M ² is Mn, Ge, By occluding and releasing at least one of Sn and Sb, lithium ions, the range of 0 ≦ x ≦ 2 is reversibly changed. However, while investigating the electrochemical characteristics of the new positive electrode material, the novel positive electrode material was found to have a characteristic that the resistance of the battery during charging significantly increases when the remaining capacity decreases.

  As a reason for having such characteristics, as a result of intensive studies, in a region where the remaining capacity is less than the characteristic change threshold, it is based on a strong covalent bond with oxygen such as Sn and Ge in order to secure a new lithium diffusion path. This is probably because mass transfer in a strong layered rock-salt crystal is necessary, whereas in the region where the residual capacity is equal to or greater than the characteristic change threshold, a diffusion path has already been formed and no further mass transfer is necessary. . In the present invention, the remaining capacity means the remaining capacity as a battery. When the remaining capacity is low, the resistance is high. And as above-mentioned, it considers that this high resistance originates in the structural change of the positive electrode material in the process of forming a lithium diffusion path. The irreversible capacity generated in the positive electrode active material during the first charge / discharge is also found. The above remaining capacity does not necessarily match the lithium desorption amount in the above-described positive electrode active material chemical formula. Even after the first charge and discharge that generates a certain irreversible capacity, in the state where a large amount of lithium is included, as described above, it becomes high resistance to form and secure a new lithium diffusion path at the time of battery output, that is, It has been found that it has thresholds of high resistance and low resistance.

  Incidentally, a hybrid vehicle or an electric vehicle is equipped with a motor that generates a driving force for driving the vehicle. In addition, a lithium ion battery that supplies power to the motor is mounted. When the driving force for driving the vehicle is generated by the motor, electric power is supplied from the lithium ion battery to the motor. On the other hand, when the motor is in a regenerative state, electric power generated by the motor is supplied to the lithium ion battery, and the lithium ion battery is charged. Thereby, the electric power generated by the motor in the regenerative state can be used effectively. As a result, the efficiency of the hybrid vehicle and the electric vehicle can be improved.

  When a battery composed of the above-described new positive electrode material is applied to such a hybrid vehicle or an electric vehicle, when the remaining capacity decreases, power is supplied from the motor in a regenerative state to the battery composed of the new positive electrode material. At the same time, there is a concern that the amount of heat generation and power consumption will increase due to the increase in resistance, and that the life will be shortened and that the regenerative power will not be fully utilized. In addition, even when charging from an external commercial power source such as an electric vehicle or a plug-in hybrid vehicle, if the remaining capacity decreases, there is a concern that the amount of heat generated during charging or power consumption may increase due to an increase in resistance.

   The present invention has been made in view of such circumstances, and is capable of supplying power to a battery composed of a novel positive electrode material while suppressing an increase in battery temperature and power consumption during charging. An object is to provide a device and a charging method.

The first invention made to achieve the above object has a layered rock salt type crystal structure, a transition metal has a local structure of six coordinates, and has a chemical formula Li _2-x Ni _α M ¹ _β M ^2. γO _4-ε (where 0.50 <α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, and M ² is , Mn, Ge, Sn, Sb, a lithium transition metal oxide represented by the following: a lithium transition metal oxide that can reversibly change the range of 0 ≦ x ≦ 2 by occluding and releasing lithium ions) The resistance when the remaining capacity is less than the characteristic change threshold is greater than the resistance when the remaining capacity is greater than or equal to the characteristic change threshold, and the resistance when the remaining capacity is 0% is more than twice the resistance when the residual capacity is greater than or equal to the characteristic change threshold A battery with the characteristics to become normal charging A main power source that supplies power to the battery by flowing a current and charges the battery, an auxiliary power source that supplies power to the battery and charges the battery by flowing a precharge current smaller than the normal charging current, and a remaining capacity of the battery A control unit that controls the auxiliary power source to supply power from the auxiliary power source to the battery and charges the battery until the remaining capacity of the battery reaches at least the characteristic change threshold.

  According to this configuration, when the remaining capacity of the battery is less than the characteristic change threshold, power is supplied from the auxiliary power source to the battery, and the battery is charged until the remaining capacity of the battery reaches at least the characteristic change threshold. Therefore, it is possible to eliminate a situation in which power is supplied from the main power source to the battery in a state where the remaining capacity of the battery is less than the characteristic change threshold, that is, in a state where the resistance is large. Therefore, power can be supplied from the main power supply to the battery without reducing the current. In addition, when the remaining capacity of the battery is less than the characteristic change threshold, the battery is charged by flowing a precharge current smaller than the normal charge current. Therefore, even if the remaining capacity becomes less than the characteristic change threshold value and the resistance increases, it is possible to suppress an increase in battery temperature and an increase in power consumption.

A second invention made to achieve the above object has a layered rock salt type crystal structure, a transition metal has a six-coordinate local structure, and has the chemical formula Li _2-x Ni _α M ¹ _β M ^2. γO _4-ε (where 0.50 <α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, and M ² is , Mn, Ge, Sn, Sb, a lithium transition metal oxide represented by the following: a lithium transition metal oxide that can reversibly change the range of 0 ≦ x ≦ 2 by occluding and releasing lithium ions) The resistance when the remaining capacity is less than the characteristic change threshold is greater than the resistance when the remaining capacity is greater than or equal to the characteristic change threshold, and the resistance when the remaining capacity is 0% is more than twice the resistance when the residual capacity is greater than or equal to the characteristic change threshold From the main power supply. A charging method for a battery in which electric power is supplied and charged by flowing an electric current, and when the remaining capacity of the battery is less than a characteristic change threshold, a precharging current smaller than the normal charging current is supplied from a power supply different from the main power supply Thus, power is supplied to the battery, and the battery is charged until the remaining capacity of the battery reaches at least the characteristic change threshold.

  According to this method, when the remaining capacity of the battery is less than the characteristic change threshold, power is supplied to the battery from a power source different from the main power supply, and the battery is charged until the remaining capacity of the battery reaches at least the characteristic change threshold. Therefore, it is possible to eliminate a situation in which power is supplied from the main power source to the battery in a state where the remaining capacity of the battery is less than the characteristic change threshold, that is, in a state where the resistance is large. Therefore, power can be supplied from the main power supply to the battery without reducing the current. In addition, when the remaining capacity of the battery is less than the characteristic change threshold, the battery is charged by flowing a precharge current smaller than the normal charge current. Therefore, even if the remaining capacity becomes less than the characteristic change threshold and the resistance increases, it is possible to suppress an increase in battery temperature and an increase in power consumption.

It is a circuit diagram of the charging device in a 1st embodiment. It is a perspective view of the lithium ion battery which comprises the battery in FIG. It is the III-III arrow sectional drawing in FIG. It is a graph which shows the characteristic of resistance with respect to the remaining capacity of the battery in FIG. It is a graph which shows the characteristic of the characteristic change threshold value periphery in FIG. 2 is a flowchart for explaining the operation of the charging device in FIG. 1. It is a 1st circuit diagram for demonstrating operation | movement of the charging device in FIG. FIG. 4 is a second circuit diagram for explaining the operation of the charging device in FIG. 1. FIG. 4 is a third circuit diagram for explaining the operation of the charging device in FIG. 1. It is a circuit diagram of the charging device in 2nd Embodiment. It is a flowchart for demonstrating operation | movement of the charging device in FIG. FIG. 11 is a first circuit diagram for explaining an operation of the charging device in FIG. 10. FIG. 11 is a second circuit diagram for explaining the operation of the charging device in FIG. 10.

  Next, an embodiment is given and this invention is demonstrated in detail. In this embodiment, the example which applied the charging device which concerns on this invention to the charging device mounted in a vehicle is shown.

(First embodiment)
First, the structure of the charging device of 1st Embodiment is demonstrated with reference to FIGS.

  A charging device 1 shown in FIG. 1 is a device that charges a battery 10 mounted on a vehicle. The charging device 1 includes a battery 10, a power conversion circuit 11, a motor 12, an auxiliary power supply 13, and a control circuit 14. Here, the power conversion circuit 11 and the motor 12 correspond to the main power source of the present invention. The control circuit 14 corresponds to the control unit of the present invention.

  The battery 10 is a chargeable / dischargeable secondary battery that supplies power to the motor 12 via the power conversion circuit 11. The battery 10 is configured by connecting a plurality of lithium ion batteries 100 shown in FIGS. 2 and 3.

  The lithium ion battery 100 includes a positive electrode 100a, a negative electrode 100b, a nonaqueous electrolyte 100c, a separator 100d, and a case 100e.

  The positive electrode 100a includes a positive electrode current collector 100f and a positive electrode active material layer 100g.

  The positive electrode current collector 100f is a thin plate-like member made of a metal such as aluminum.

The positive electrode active material layer 100g is made of an oxide capable of inserting and extracting lithium ions, and is formed on the surface of the positive electrode current collector 100f. Oxide to form the cathode active material layer 100g has a layered rock-salt crystal structure, the transition metal comprises a local structure 6 coordination formula ^{_{Li 2-x Ni α M 1}} β M 2 γO 4- _ε (where 0.50 <α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, M ² is Mn, A lithium transition metal oxide represented by the following formula: a lithium transition metal oxide represented by at least one of Ge, Sn, and Sb, which reversibly changes the range of 0 ≦ x ≦ 2 by inserting and extracting lithium ions. Yes. The positive electrode active material layer 100g is formed by mixing the above-described oxide together with a conductive material, a binder, and the like in a solvent, and applying and drying the surface of the positive electrode current collector 100f. The conductive material is, for example, a carbon material or a conductive polymer material. Examples of the carbon material include ketjen black, acetylene black, carbon black, graphite, carbon nanotube, and amorphous carbon. The conductive polymer material is polyaniline, polypyrrole, polythiophene, polyacetylene, or polyacene. The binder is, for example, a polymer material. The polymer material is polyvinylidene fluoride, polytetrafluoroethylene, ethylene propylene rubber, styrene butadiene rubber, nitrile rubber, fluorine rubber, or an acrylic binder. The solvent is, for example, water or N-methyl-2-pyrrolidone.

  The negative electrode 100b includes a negative electrode current collector 100h and a negative electrode active material layer 100i.

  The negative electrode current collector 100h is a thin plate member made of a metal such as Cu.

  The negative electrode active material layer 100i is made of a compound capable of occluding and releasing lithium ions, and is formed on the surface of the negative electrode current collector 100h. The compound that forms the negative electrode active material layer 100i is, for example, a metal material such as a lithium foil, an alloy material containing Si, Sn, Cu, or the like, a carbon material such as graphite or coke, or a titanium oxide. The negative electrode active material layer 100i is prepared by mixing the above-described compound forming the negative electrode active material layer 100i together with the same conductive material and binder as the positive electrode 100a in the same solvent as the positive electrode 100a, and forming the negative electrode current collector 100h. It is formed by applying and drying on the surface.

  The nonaqueous electrolyte 100c enables movement of charge carriers such as ions between the positive electrode 100a and the negative electrode 100b.

  The separator 100d is a thin plate-like member that insulates the positive electrode 100a and the negative electrode 100b while allowing the movement of charge carriers between the positive electrode 100a and the negative electrode 100b. The separator 100d is, for example, a porous synthetic resin film, in particular, a porous film made of polyolefin polymer, cellulose, or glass fiber, or a nonwoven fabric. The separator 100d may contain ceramics as its constituent elements.

  The case 100e is a member that accommodates the positive electrode 100a, the negative electrode 100b, the separator 100d, and the nonaqueous electrolyte 100c. The case 100e is formed of, for example, a laminate film. The case 100e includes a positive electrode terminal 100j and a negative electrode terminal 100k. The positive terminal 100j and the negative terminal 100k are fixed to the case 100e with one end projecting into the internal space of the case 100e and the other end projecting outside the case 100e.

  The positive electrodes 100a and the negative electrodes 100b are alternately stacked. The separator 100d is provided between the positive electrode 100a and the negative electrode 100b. The positive electrode 100a, the negative electrode 100b, and the separator 100d are accommodated in the internal space of the case 100e. The end of the positive electrode 100a is connected to the positive electrode terminal 100j, and the end of the negative electrode 100b is connected to the negative electrode terminal 100k. The nonaqueous electrolyte 100c is accommodated in the internal space of the case 100e together with the positive electrode 100a, the negative electrode 100b, and the separator 100d.

In the battery 10, the oxide forming the positive electrode active material layer 100 g has a layered rock-salt crystal structure, the transition metal has a six-coordinate local structure, and has the chemical formula Li _2−x Ni _α M ¹ _β M ² γO _4-ε (where 0.50 <α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, M ² A lithium transition metal oxide represented by the following formula: at least one of Mn, Ge, Sn, and Sb, which reversibly changes the range of 0 ≦ x ≦ 2 by occluding and releasing lithium ions) Contains as a substance. As a result, compared with the case where such a substance is not included, safety is high and the capacity per volume can be increased. Further, the resistance when the remaining capacity is less than the characteristic change threshold is larger than the resistance when the remaining capacity is equal to or greater than the characteristic change threshold, and the resistance when the remaining capacity is 0% is more than twice the resistance when the residual capacity is equal to or greater than the characteristic change threshold. It has the characteristic which becomes. Here, the characteristic change threshold is a remaining capacity indicating a boundary where the value of the resistance changes in a graph showing the resistance characteristic with respect to the remaining capacity of the battery 10. For example, as shown in FIGS. 4 and 5, with the characteristic change threshold of 2% as a boundary, the resistance of the battery 10 when the remaining capacity is less than 2% is larger than the resistance when the remaining capacity is 2% or more. Furthermore, when the remaining capacity is 0%, the resistance of the battery 10 is 5 times or more of the resistance when the remaining capacity is 2% or more.

  The reason why the battery 10 has such characteristics is that, based on intensive studies, in a region where the remaining capacity is less than the characteristic change threshold, it is based on a covalent bond of Sn, Ge, and oxygen in order to secure a new lithium diffusion path. While mass transfer including heavy elements such as Sn and Ge is necessary when deforming a strong layered rock salt type crystal, a diffusion path has already been formed in the region where the residual capacity exceeds the characteristic change threshold. This is probably because no further mass transfer is necessary.

  The power conversion circuit 11 shown in FIG. 1 is controlled by the control circuit 14, converts the direct current supplied from the battery 10 into a three-phase alternating current, and supplies it to the motor 12, thereby driving the motor 12 to drive the vehicle. Is a circuit that generates Moreover, it is also a circuit which charges the battery 10 and the auxiliary power supply 13 by converting the three-phase alternating current generated by the motor 12 in the regenerative state into a direct current and supplying it to the battery 10 and the auxiliary power supply 13. The power conversion circuit 11 is connected to the battery 10, the motor 12, and the auxiliary power source 13, respectively. Further, it is connected to the control circuit 14.

  The motor 12 is a device that generates a driving force for driving the vehicle when supplied with a three-phase alternating current. It is also a device that generates a three-phase alternating current when it is in a regenerative state. The motor 12 is connected to the power conversion circuit 11.

  The auxiliary power supply 13 is a chargeable / dischargeable power supply that is controlled by the control circuit 14 and supplies power to the battery 10 to charge the battery 10. The auxiliary power supply 13 includes at least one of a lead storage battery, a lithium ion battery, a nickel metal hydride battery, and a capacitor. The auxiliary power supply 13 is set to have a resistance smaller than that of the battery 10 so that power can be supplied to the battery 10.

  The control circuit 14 is a circuit that estimates the remaining capacity based on information obtained from the battery 10 and the auxiliary power supply 13 and controls the power conversion circuit 11 and the auxiliary power supply 13 based on the estimated remaining capacity. . When the driving force for driving the vehicle is generated in the motor 12, the control circuit 14 controls the power conversion circuit 11, converts the direct current supplied from the battery 10 into a three-phase alternating current, and supplies the three-phase alternating current to the motor 12.

  When charging the battery 10, if the remaining capacity of the battery 10 is equal to or greater than the characteristic change threshold, the control circuit 14 controls the power conversion circuit 11 to convert the three-phase alternating current generated by the motor 12 in the regenerative state into direct current. Conversion is performed to supply power to the battery 10 and the battery 10 is charged. At that time, electric power is supplied to the battery 10 by flowing a normal charging current. The normal charging current is determined according to the current value that can be supplied to the battery 10 in the regenerative state, and is set based on the resistance of the battery 10 when the remaining capacity of the battery 10 is equal to or greater than the characteristic change threshold. On the other hand, when the remaining capacity of the battery 10 is less than the characteristic change threshold, the control circuit 14 controls the auxiliary power supply 13 to supply power from the auxiliary power supply 13 to the battery 10, so that the remaining capacity of the battery 10 is at least characteristic. The battery 10 is charged until the change threshold is reached. At that time, electric power is supplied to the battery 10 by flowing a preliminary charging current smaller than the normal charging current. The preliminary charging current is set based on the resistance of the battery 10 when the remaining capacity of the battery 10 is less than the characteristic change threshold. When the remaining capacity of the auxiliary power supply 13 is less than the auxiliary power supply charging threshold, the control circuit 14 controls the power conversion circuit 11 to convert the three-phase alternating current generated by the motor 12 in the regenerative state into direct current to assist. Power is supplied to the power supply 13 and the auxiliary power supply 13 is charged. Here, the auxiliary power supply charging threshold indicates a remaining capacity of the auxiliary power supply 13 that is required at a minimum when the battery 10 is charged by supplying power from the auxiliary power supply 13 to the battery 10.

  Next, the operation of the charging apparatus according to the first embodiment will be described with reference to FIGS. 1 and 6 to 9.

  As shown in FIG. 6, in step S <b> 100, the control circuit 14 shown in FIG. 1 estimates the remaining capacity of the battery 10 based on information obtained from the battery 10. In step S101, it is determined whether or not the estimated remaining capacity of the battery 10 is equal to or greater than a characteristic change threshold.

  When it is determined that the estimated remaining capacity of the battery 10 is less than the characteristic change threshold, the resistance of the battery 10 is greater than when the estimated remaining capacity is greater than or equal to the characteristic change threshold. Therefore, it is necessary to reduce the resistance by setting the remaining capacity of the battery 10 to be equal to or greater than the characteristic change threshold. Therefore, in step S102, the control circuit 14 precharges the battery 10. Specifically, the auxiliary power supply 13 is controlled, and as shown in FIG. 7, the battery 10 is supplied with electric power by flowing a preliminary charging current smaller than the normal charging current from the auxiliary power supply 13 to the battery 10. Charge. Thereby, the temperature rise of the battery 10 at the time of charge and the increase in power consumption can be suppressed. Then, as shown in FIG. 6, the preliminary charging of the battery 10 is repeated until the estimated remaining capacity of the battery 10 becomes equal to or greater than the characteristic change threshold. That is, the preliminary charging of the battery 10 is repeated until the remaining capacity of the battery 10 reaches at least the characteristic change threshold value. Thereby, the resistance of the battery 10 can be reduced.

  On the other hand, when it is determined that the estimated remaining capacity of the battery 10 is equal to or greater than the characteristic change threshold, the resistance of the battery 10 is small. Therefore, it is not necessary to precharge the battery 10 as described above.

  Thereafter, in step S <b> 103, the control circuit 14 estimates the remaining capacity of the auxiliary power supply 13 based on information obtained from the auxiliary power supply 13. In step S104, it is determined whether or not the estimated remaining capacity of the auxiliary power supply 13 is equal to or greater than an auxiliary power supply charging threshold.

  When it is determined that the estimated remaining capacity of the auxiliary power supply 13 is equal to or greater than the auxiliary power supply charging threshold, sufficient power for precharging the battery 10 is secured in the auxiliary power supply 13 and the auxiliary power supply 13 needs to be charged. Absent. Therefore, in step S105, the control circuit 14 normally charges the battery 10. Specifically, in the regenerative state that occurs at an arbitrary timing, the power conversion circuit 11 is controlled, and the three-phase alternating current generated by the motor 12 that has entered the regenerative state is converted into direct current to supply power to the battery 10. The battery 10 is charged. More specifically, the power conversion circuit 11 is controlled, and power is supplied to the battery 10 by flowing a normal charging current from the power conversion circuit 11 to the battery 10 as shown in FIG.

  On the other hand, as shown in FIG. 6, when it is determined that the estimated remaining capacity of the auxiliary power supply 13 is less than the auxiliary power supply charging threshold, sufficient power for precharging the battery 10 is not secured in the auxiliary power supply 13. First, the auxiliary power supply 13 needs to be charged. Therefore, in step S106, the control circuit 14 normally charges the battery 10 and also charges the auxiliary power source 13. Specifically, the power conversion circuit 11 is controlled in a regenerative state that occurs at an arbitrary timing, and the battery 10 is normally charged as shown in FIG. Further, the power conversion circuit 11 is controlled to convert the three-phase alternating current generated by the motor 12 in the regenerative state into a direct current and supply power to the auxiliary power supply 13, and the auxiliary power supply 13 is also charged. Thereby, the electric power generated by the motor 12 in the regenerative state can be effectively used to secure the electric power for precharging the battery 10.

  Next, the effect of the charging device of the first embodiment will be described.

According to the first embodiment, the charging device 1 includes a battery 10, a power conversion circuit 11, a motor 12, an auxiliary power supply 13, and a control circuit 14. The battery 10 has a layered rock salt type crystal structure, a transition metal has a 6-coordinate local structure, and has a chemical formula Li _2-x Ni _α M ¹ _β M ² γO _4-ε (where 0.50 <Α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, and M ² is at least one of Mn, Ge, Sn, and Sb. In addition, a lithium transition metal oxide represented by the following can be reversibly changed by occluding and releasing lithium ions: As a result, the resistance when the remaining capacity is less than the characteristic change threshold is larger than the resistance when the remaining capacity is equal to or greater than the characteristic change threshold, and more than twice the resistance when the remaining capacity is 0% or greater. Will have the following characteristics. The control circuit 14 controls the power conversion circuit 11, converts the three-phase alternating current generated by the motor 12 in the regenerative state into direct current, supplies power to the battery 10, and charges the battery 10. When the remaining capacity of the battery 10 is less than the characteristic change threshold, the control circuit 14 controls the auxiliary power supply 13 to supply power from the auxiliary power supply 13 to the battery 10, and the remaining capacity of the battery 10 is at least set to the characteristic change threshold. The battery 10 is charged until That is, as a charging method, when the remaining capacity of the battery 10 is less than the characteristic change threshold, the regenerative state of the motor 12 and the power conversion circuit 11 controlled by the control circuit 14 are different from those. Electric power is supplied to the battery 10 by flowing a precharge current smaller than the normal charge current from the auxiliary power supply 13 controlled by the control circuit 14. Then, the battery 10 is charged until the remaining capacity of the battery 10 reaches at least the characteristic change threshold. Therefore, a situation where power is supplied to the battery 10 from the motor 12 in the regenerative state via the power conversion circuit 11 in a state where the remaining capacity of the battery 10 is less than the characteristic change threshold, that is, in a state where the resistance is large is eliminated. be able to. Therefore, electric power can be supplied to the battery 10 from the motor 12 in the regenerative state via the power conversion circuit 11 without reducing the current. In addition, when the remaining capacity of the battery 10 is less than the characteristic change threshold, the battery 10 is charged by flowing a precharge current smaller than the normal charge current. Therefore, even if the remaining capacity becomes less than the characteristic change threshold and the resistance increases, it is possible to suppress an increase in the temperature of the battery 10 and an increase in power consumption. Therefore, the situation where the life of the battery 10 is shortened can be suppressed.

  When the remaining capacity of the battery 10 is less than the characteristic change threshold, the auxiliary power supply 13 charges the battery 10 by performing preliminary charging. According to the first embodiment, the characteristic change threshold of the battery 10 is 2%, which is very small. Therefore, it is not necessary to precharge until the remaining capacity of the battery 10 is less than 2%. Therefore, the interval from the preliminary charging to the preliminary charging can be lengthened. That is, the number of preliminary charging can be suppressed. As a result, it is possible to suppress a situation where frequent preliminary charging is performed.

  According to the first embodiment, the auxiliary power supply 13 is chargeable / dischargeable. When the remaining capacity is less than the auxiliary power supply charging threshold, electric power is supplied and charged. Therefore, sufficient power for precharging can be ensured. Therefore, the battery 10 can be reliably precharged as necessary.

  According to the first embodiment, when the remaining capacity of the auxiliary power supply 13 is less than the auxiliary power supply charging threshold, the control circuit 14 controls the power conversion circuit 11 to generate a three-phase alternating current generated by the motor 12 in the regenerative state. The power is converted into direct current and power is supplied to the auxiliary power supply 13 to charge the auxiliary power supply 13. Therefore, the auxiliary power supply 13 can be reliably charged. In addition, the auxiliary power supply 13 is charged using the electric power generated by the motor 12 in the regenerative state. Therefore, the efficiency of the charging device 1 can be improved.

  According to the first embodiment, the auxiliary power supply 13 includes at least one of a lead storage battery, a lithium ion battery, a nickel metal hydride battery, and a capacitor. Therefore, it is possible to ensure the power for precharging.

  According to the first embodiment, the auxiliary power supply 13 is set so that the resistance is smaller than that of the battery 10. Therefore, it is possible to suppress the loss of the auxiliary power supply 13 when performing preliminary charging and charging the auxiliary power supply 13.

  In the first embodiment, the example in which the characteristic change threshold of the battery 10 is 2% is given, but the present invention is not limited to this. The characteristic change threshold value of the battery 10 may be a predetermined value of 10% or less, or may be a predetermined value of 15% or less. If the predetermined value is 20% or less, it is possible to suppress a situation where frequent precharging is performed within a practical range.

(Second Embodiment)
Next, the charging device according to the second embodiment will be described. The charging device of the second embodiment supplies power to the lithium ion battery from the auxiliary power source that can be charged and discharged by the charging device of the first embodiment, whereas the charging device of the second embodiment is from an auxiliary power source that includes a commercial power source and a power conversion circuit. The power is supplied to the lithium ion battery. Therefore, unlike the charging device of the first embodiment, the auxiliary power source cannot be charged.

  First, the structure of the charging device of 2nd Embodiment is demonstrated with reference to FIG.

  As shown in FIG. 10, the charging device 2 includes a battery 20, a power conversion circuit 21, a motor 22, an auxiliary power source 23, and a control circuit 24.

  The battery 20, the power conversion circuit 21, and the motor 22 are the same as the battery 10, the power conversion circuit 11, and the motor 12 of the first embodiment, and are configured similarly.

  The auxiliary power source 23 is a power source that is controlled by the control circuit 24 and supplies power to the battery 20 to charge the battery 20. Unlike the auxiliary power supply 13 of the first embodiment, it cannot be charged. It has only the function of supplying power to the battery 20. The auxiliary power supply 23 is set to have a resistance smaller than that of the battery 20 so as to supply power to the battery 20. The auxiliary power supply 23 includes a commercial power supply 230 and a power conversion circuit 231.

  The commercial power source 230 is a power source that outputs an alternating current provided in a house or the like. The power conversion circuit 231 is a circuit that is controlled by the control circuit 24, converts alternating current supplied from the commercial power supply 230 into direct current, supplies the direct current to the battery 20, and charges the battery 20. The power conversion circuit 231 is connected to the commercial power supply 230 and the battery 20 respectively. Further, it is connected to the control circuit 24.

  The control circuit 24 is a circuit that estimates the remaining capacity of the battery 20 based on information obtained from the battery 20 and controls the power conversion circuit 21 and the auxiliary power source 23 based on the estimated remaining capacity of the battery 20. When causing the motor 22 to generate a driving force for driving the vehicle, the control circuit 24 controls the power conversion circuit 21 to convert the direct current supplied from the battery 20 into a three-phase alternating current and supply the three-phase alternating current to the motor 22.

  When charging the battery 20, if the remaining capacity of the battery 20 is equal to or greater than the characteristic change threshold, the control circuit 24 controls the power conversion circuit 21 to convert the three-phase alternating current generated by the regenerated motor 22 into direct current. Conversion is performed to supply power to the battery 20, and the battery 20 is charged. At that time, electric power is supplied to the battery 20 by flowing a normal charging current. The normal charging current is determined according to the current value that can be supplied to the battery 20 in the regenerative state, and is set based on the resistance of the battery 20 when the remaining capacity of the battery 20 is equal to or greater than the characteristic change threshold. On the other hand, when the remaining capacity of the battery 20 is less than the characteristic change threshold value, the control circuit 24 controls the power conversion circuit 231 to convert the alternating current supplied from the commercial power supply 230 into direct current and supply power to the battery 20. The battery 20 is charged until the remaining capacity of the battery 20 reaches at least the characteristic change threshold. At that time, electric power is supplied to the battery 20 by flowing a preliminary charging current smaller than the normal charging current. The preliminary charging current is set based on the resistance of the battery 20 when the remaining capacity of the battery 20 is less than the characteristic change threshold. After the preliminary charging is performed, charging may be continued from the auxiliary power source 23 with the normal charging current. After the preliminary charging is performed, charging may be continued from the auxiliary power source 23 with the normal charging current.

  Next, the operation of the charging apparatus according to the second embodiment will be described with reference to FIGS.

  As shown in FIG. 11, in step S <b> 200, the control circuit 24 shown in FIG. 10 estimates the remaining capacity of the battery 20 based on information obtained from the battery 20. In step S201, it is determined whether the estimated remaining capacity of the battery 20 is equal to or greater than a characteristic change threshold.

  When it is determined that the estimated remaining capacity of the battery 20 is less than the characteristic change threshold, the resistance of the battery 20 is greater than when the estimated remaining capacity is greater than or equal to the characteristic change threshold. Therefore, it is necessary to reduce the resistance by setting the remaining capacity of the battery 20 to be equal to or greater than the characteristic change threshold. Therefore, in step S202, the control circuit 24 precharges the battery 20. Specifically, the power conversion circuit 231 is controlled, the alternating current supplied from the commercial power supply 230 is converted into direct current, the power is supplied to the battery 20, and the battery 20 is charged. More specifically, the power conversion circuit 231 is controlled, and power is supplied to the battery 20 by flowing a precharge current smaller than the normal charge current from the power conversion circuit 231 to the battery 20 as shown in FIG. 20 is charged. Thereby, the temperature rise of the battery 20 at the time of charge and the increase in power consumption can be suppressed. Then, as shown in FIG. 11, the preliminary charging of the battery 20 is repeated until the estimated remaining capacity of the battery 20 becomes equal to or greater than the characteristic change threshold. That is, the preliminary charging of the battery 20 is repeated until the remaining capacity of the battery 20 reaches at least the characteristic change threshold. Thereby, the resistance of the battery 20 can be reduced.

  On the other hand, when it is determined that the estimated remaining capacity of the battery 20 is equal to or greater than the characteristic change threshold, the resistance of the battery 20 is small. Therefore, it is not necessary to precharge the battery 20 as described above. Therefore, in step S203, the control circuit 24 normally charges the battery 20. Specifically, in the regenerative state that occurs at an arbitrary timing, the power conversion circuit 21 is controlled, and the three-phase alternating current generated by the motor 22 that has entered the regenerative state is converted into direct current to supply power to the battery 20. The battery 20 is charged. More specifically, the power conversion circuit 21 is controlled, and the battery 20 is charged by supplying power to the battery 20 by flowing a normal charging current from the power conversion circuit 21 to the battery 20 as shown in FIG. Alternatively, after charging from the auxiliary power source 23 to the characteristic threshold or more with the preliminary charging current, charging may be continued from the auxiliary power source 23 with the normal charging current.

  Next, effects of the charging device according to the second embodiment will be described.

According to the second embodiment, the charging device 2 includes a battery 20, a power conversion circuit 21, a motor 22, an auxiliary power supply 23, and a control circuit 24. The battery 20 has a layered rock-salt crystal structure, a transition metal has a six-coordinate local structure, and has a chemical formula of Li _2-x Ni _α M ¹ _β M ² γO _4-ε (where 0.50 <Α ≦ 1.33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, and M ² is at least one of Mn, Ge, Sn, and Sb. In addition, a lithium transition metal oxide represented by the following can be reversibly changed by occluding and releasing lithium ions: As a result, the resistance when the remaining capacity is less than the characteristic change threshold is larger than the resistance when the remaining capacity is equal to or greater than the characteristic change threshold, and more than twice the resistance when the remaining capacity is 0% or greater. Will have the following characteristics. The control circuit 24 controls the power conversion circuit 21, converts the three-phase alternating current generated by the motor 22 in the regenerative state into direct current, supplies power to the battery 20, and charges the battery 20. When the remaining capacity of the battery 20 is less than the characteristic change threshold, the control circuit 24 controls the power conversion circuit 231 to supply power from the commercial power supply 230 to the battery 20 via the power conversion circuit 231. The battery 20 is charged until the remaining capacity reaches at least the characteristic change threshold. That is, as a charging method, when the remaining capacity of the battery 20 is less than the characteristic change threshold, the regenerative state of the motor 22 and the power conversion circuit 21 controlled by the control circuit 24 are different from those. Electric power is supplied to the battery 20 by flowing a precharge current smaller than the normal charge current from the commercial power supply 230 via the power conversion circuit 231 controlled by the control circuit 24. Then, the battery 20 is charged until the remaining capacity of the battery 20 reaches at least the characteristic change threshold. For this reason, a situation in which power is supplied to the battery 20 from the motor 22 in the regenerative state via the power conversion circuit 21 in a state where the remaining capacity of the battery 20 is less than the characteristic change threshold, that is, in a state where the resistance is large is eliminated. be able to. Therefore, electric power can be supplied to the battery 20 from the motor 22 in the regenerative state via the power conversion circuit 21 without reducing the current. Moreover, when the remaining capacity of the battery 20 is less than the characteristic change threshold, the battery 20 is charged by flowing a precharge current smaller than the normal charge current. Therefore, even if the remaining capacity becomes less than the characteristic change threshold and the resistance increases, it is possible to suppress an increase in the temperature of the battery 20 and an increase in power consumption. Therefore, the situation where the life of the battery 20 is shortened can be suppressed.

  According to the second embodiment, by having the same configuration as that of the first embodiment, the same effect as that of the first embodiment corresponding to the same configuration can be obtained.

  In the second embodiment, the auxiliary power supply 23 includes the commercial power supply 230 and the power conversion circuit 231. However, the present invention is not limited to this. The auxiliary power source 23 may have an alternator.

  DESCRIPTION OF SYMBOLS 1 ... Charging device, 10 ... Battery, 100 ... Lithium ion battery, 100a ... Positive electrode, 100g ... Positive electrode active material layer, 11 ... Power conversion circuit, 12 ... Motor, 13 ... Power supply, 14 ... Control circuit

Claims (10)

It has a layered rock salt type crystal structure, and the transition metal has a 6-coordinate local structure, and has the chemical formula Li _2-x Ni _α M ¹ _β M ² γO _4-ε (where 0.50 <α ≦ 1 .33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, M ² is at least one of Mn, Ge, Sn, and Sb, and lithium ions. A lithium transition metal oxide represented by the following formula: 0 ≦ x ≦ 2 that reversibly changes by occlusion and release, and the resistance when the remaining capacity is less than the characteristic change threshold A battery (10, 20) having a characteristic that is greater than the resistance when the characteristic change threshold is equal to or greater than the resistance change when the remaining capacity is 0% and is more than twice the resistance when the residual capacity is equal to or greater than the characteristic change threshold;
A main power supply (11, 12, 21, 22) for supplying power to the battery by charging a normal charging current and charging the battery;
An auxiliary power source (13, 23) for supplying power to the battery by charging a pre-charge current smaller than the normal charge current and charging the battery;
If the remaining capacity of the battery is less than the characteristic change threshold, the auxiliary power is controlled to supply power from the auxiliary power to the battery, and the battery is kept until the remaining capacity of the battery reaches at least the characteristic change threshold. A control unit (14, 24) for charging;
A charging device.   The charging device according to claim 1, wherein the battery has a predetermined value with the characteristic change threshold of 20% or less.   The charging device according to claim 1 or 2, wherein the auxiliary power supply (10) is chargeable / dischargeable and is supplied and charged when the remaining capacity is less than an auxiliary power supply charging threshold.   The charging device according to claim 3, wherein the main power supply (11, 12) supplies power to the auxiliary power supply to charge the auxiliary power supply when a remaining capacity of the auxiliary power supply is less than the auxiliary power supply charging threshold.   The charging device according to claim 3 or 4, wherein the auxiliary power source includes at least one of a lead storage battery, a lithium ion battery, a nickel metal hydride battery, and a capacitor.   The charging device according to claim 1, wherein the auxiliary power source includes an alternator. The auxiliary power source (23)
A commercial power source (230) for outputting alternating current;
A power conversion circuit (231) for converting alternating current supplied from the commercial power source into direct current to supply power to the battery and charging the battery;
The charging device according to claim 1, comprising:   The charging device according to claim 1, wherein the auxiliary power source has a resistance smaller than that of the battery. It has a layered rock salt type crystal structure, and the transition metal has a 6-coordinate local structure, and has the chemical formula Li _2-x Ni _α M ¹ _β M ² γO _4-ε (where 0.50 <α ≦ 1 .33, 0 ≦ β <0.67, 0 ≦ γ ≦ 1.33, M ¹ is at least ^one of Co, Al, and Ga, M ² is at least one of Mn, Ge, Sn, and Sb, and lithium ions. A lithium transition metal oxide represented by the following formula: 0 ≦ x ≦ 2 that reversibly changes by occlusion and release, and the resistance when the remaining capacity is less than the characteristic change threshold It has a characteristic that the resistance when the remaining capacity is 0% or more when the remaining capacity is 0% or more is more than twice the resistance when the remaining capacity is greater than or equal to the characteristic change threshold, and the normal charging current from the main power supply. Power is supplied by flowing A method of charging a battery to be conductive,
When the remaining capacity of the battery is less than the characteristic change threshold, power is supplied to the battery by flowing a precharging current smaller than the normal charging current from an auxiliary power supply different from the main power supply, and the remaining capacity of the battery A charging method for charging the battery until at least the characteristic change threshold value is reached.   The charging method according to claim 9, wherein the auxiliary power source (23) converts alternating current supplied from a commercial power source into direct current, supplies power to the battery, and charges the battery.

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