JP2011041441A - Charge power limit value calculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge power limit value calculating device for optimally obtaining a charge power limit value for a battery for supplying power for driving a vehicle in accordance with utilization conditions of the battery. <P>SOLUTION: The charge power limit value calculating device includes: a usage state detecting section for detecting a power exchange state of the battery; a battery state estimating section 26 for obtaining a battery state amount on the basis of a result of detection by the usage state estimating section; a first chargeable power estimating section 28 for obtaining chargeable power when the battery is charged at a charge current limited value, on the basis of the battery state amount; a second chargeable power estimating section 36 for obtaining chargeable power when the battery is charged at a charge voltage limit value, on the basis of the battery state amount; and a selecting section 32 for selecting either the chargeable power obtained by the first chargeable power estimating section 28 or the chargeable power obtained by the second chargeable power estimating section 36 in accordance with a result of comparison between an output voltage of the battery and the charge voltage limit value, and obtaining chargeable power characteristics indicating a change in the chargeable power with time on the basis of a result of selection. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging power limit value calculation device that determines a charging power limit value for a battery for supplying vehicle driving power.

  Electric vehicles such as electric vehicles and hybrid vehicles are widely used. The electric vehicle includes a motor generator, and is accelerated by a driving force of the motor generator and decelerated by regenerative power generation braking of the motor generator. In order to supply electric power to the motor generator and collect electric power generated by the motor generator, a secondary battery that can be repeatedly charged and discharged is mounted on the electric vehicle.

  The following Patent Document 1 and Patent Document 2 describe a technique for limiting the charge / discharge power of a battery in relation to the problem to be solved by the present invention. Non-Patent Document 1 and Patent Document 2 below describe an electrochemical model of a battery used for charge / discharge control according to the present invention.

JP 2003-219510 A JP 2008-42960 A

WBGu and CYWang, “THERMAL-ELECTROCHEMICAL COUPLED MODELING OF A LITHIUM-ION CELL”, ECS Proceedings Vol.99-25 (1), 2000 (USA), Electrochemical Society (ECS), 2000, pp 743-762

  The charging performance of the battery varies depending on usage conditions such as charging power and battery temperature. For this reason, when charge control is performed so that charging is performed with a constant power, there arises a problem that the battery cannot be charged with the maximum allowable power. On the other hand, when the battery is charged with excessive power, there arises a problem that the life of the battery is shortened, for example, the charge capacity is quickly reduced.

  The present invention has been made for such a problem. That is, in a charging power limit value calculation device that calculates a charging power limit value for a battery for supplying vehicle driving power, an optimum charging power limit value is determined according to the use condition of the battery, the state of the battery, and the charging characteristics of the battery. Objective.

  The present invention provides a charge power limit value calculation device that calculates a charge power limit value for a battery for supplying vehicle driving power, a use state detection unit that detects a power transfer state of the battery, and a detection result of the use state detection unit. Based on the battery state quantity, a battery state quantity estimating unit that obtains a battery state quantity, a charge current limit value is obtained, and chargeable power when the battery is charged with the current of the charge current limit value is obtained based on the battery state quantity. A chargeable power predicting unit, a second chargeable power predicting unit that obtains a charge voltage limit value and obtains chargeable power when the battery is charged with the voltage of the charge voltage limit value based on the battery state quantity; The output voltage of the battery and the charge voltage limit value are compared, and the chargeable power obtained by the first chargeable power prediction unit or the second chargeable power prediction unit is obtained according to the comparison result. And a selection unit that selects a chargeable power characteristic indicating a change over time of the chargeable power based on a selection result, and sets a charge power limit value based on the chargeable power characteristic. It is characterized by outputting.

  Further, in the charge power limit value calculation device according to the present invention, a power limit value setting unit that obtains chargeable power as a charge power limit value when a predetermined time has elapsed from a reference time based on the chargeable power characteristic. Is preferably provided.

  Moreover, in the charging power limit value calculating device according to the present invention, the selection unit is configured to obtain the charging obtained by the first chargeable power prediction unit when the output voltage of the battery is less than the charging voltage limit value. It is preferable to select the possible power.

  Further, in the charging power limit value calculation device according to the present invention, the deterioration level estimation unit that determines the deterioration level of the charging capacity of the battery and the deterioration level estimation unit based on the detection result of the use state detection unit. It is preferable to include a permissible current setting unit that determines a smaller charging current limit value as the deterioration degree is larger and provides the determined charging current limit value to the first chargeable power prediction unit.

  Further, in the charging power limit value calculation device according to the present invention, the deterioration level estimation unit that determines the deterioration level of the charging capacity of the battery and the deterioration level estimation unit based on the detection result of the use state detection unit. It is preferable to include a permissible voltage setting unit that determines a charging voltage limit value that is smaller as the degree of deterioration is greater, and that provides the determined charging voltage limit value to the second chargeable power prediction unit.

  In the charging power limit value calculation device according to the present invention, a smaller charging current limit value is determined as the deterioration degree obtained by the deterioration degree estimating unit is larger, and the predetermined charging current limit value can be charged in the first charge. It is preferable to include an allowable current setting unit to be provided to the power prediction unit.

  Further, in the charging power limit value calculation device according to the present invention, the charging depth of the battery is obtained based on the battery state quantity, and a smaller charging current limit value is determined as the obtained charging depth is larger. It is preferable to include an allowable current setting unit that supplies a current limit value to the first chargeable power prediction unit.

  Further, in the charging power limit value calculation device according to the present invention, the charging depth of the battery is determined based on the battery state quantity, and the charging voltage limit value is set to be smaller as the determined charging depth is larger, and the determined charging is performed. It is preferable that an allowable voltage setting unit that provides a voltage limit value to the second chargeable power prediction unit is provided.

  Further, in the charging power limit value calculation device according to the present invention, the charging depth of the battery is obtained based on the battery state quantity, and a smaller charging current limit value is determined as the obtained charging depth is larger. It is preferable to include an allowable current setting unit that supplies a current limit value to the first chargeable power prediction unit.

  Further, in the charging power limit value calculation device according to the present invention, based on the battery current control unit that changes the current flowing through the battery, and the change in the output voltage of the battery with respect to the current change by the battery current control unit, A battery characteristic determining unit for determining a battery characteristic constant, wherein the battery state quantity estimating unit obtains a battery state quantity based on the specific constant obtained by the battery characteristic determining unit, and the first and second charging It is preferable that the possible power prediction unit obtains the chargeable power based on the specific constant obtained by the battery determination unit.

  According to the present invention, the charging power limit value of the battery can be optimally determined according to the use condition of the battery.

It is a figure which shows the structure of the vehicle electric power control system which concerns on 1st Embodiment. It is a figure which shows the structure of the electric power limit value calculating apparatus which concerns on 1st Example. It is a figure which shows the structure and electrochemical model of a battery cell. It is a figure which shows a battery model parameter. It is a figure which shows the time waveform and chargeable electric power characteristic of a charging current limiting value. It is a figure which shows the time waveform and chargeable electric power characteristic of a charging voltage limiting value. It is a figure which shows the structure of the electric power limit value calculating apparatus which concerns on 2nd Example. It is a figure which shows each time waveform of a battery current measured value, a battery voltage measured value, and chargeable electric power. It is a figure which shows the structure of the electric power limit value calculating apparatus which concerns on 3rd Example. It is a figure which shows the example of the relationship which a charging depth vs. current limiting value table shows. It is a figure which shows the time waveform and chargeable electric power characteristic of a charging current limiting value. It is a figure which shows the example of the relationship which a charging depth versus voltage limiting value table shows. It is a figure which shows the time waveform and chargeable electric power characteristic of a charging voltage limiting value. It is a figure which shows each time waveform of a battery current measured value, a battery voltage measured value, and chargeable electric power. It is a figure which shows the structure of the electric power control system for vehicles which concerns on 2nd Embodiment. It is a figure which shows the structure of the battery diagnosis / electric power limit value calculating apparatus which concerns on 1st Example. It is a figure which shows the example of the time waveform of the battery current controlled by the current control apparatus, and the time waveform of the measurement battery voltage according to the battery current. It is a figure which shows the structure of the battery diagnosis / power limit value calculating apparatus which concerns on 2nd Example. It is a figure which shows the example of the relationship which a degradation degree vs. current limiting value table shows. It is a figure which shows the time waveform and chargeable electric power characteristic of a charging current limiting value. It is a figure which shows the example of the relationship which a deterioration degree versus voltage limiting value table shows. It is a figure which shows each time waveform of a battery current measured value, a battery voltage measured value, and chargeable electric power.

  FIG. 1 shows a configuration of a vehicle power control system according to a first embodiment of the present invention. The vehicle power control system supplies the electric power of the battery 10 to the motor generator 14 to drive the vehicle, charges the battery 10 with the electric power generated by the motor generator 14 and regeneratively brakes the vehicle. The battery 10 can be a lithium ion battery that can be repeatedly charged and discharged.

  The operation unit 16 includes an accelerator pedal, a brake pedal, and the like, and outputs operation command information corresponding to a user operation to the power control device 12.

  The power control device 12 performs AC / DC conversion between the motor generator 14 and the battery 10 while adjusting each applied voltage. When the electric power control device 12 causes the motor generator 14 to generate acceleration torque in accordance with the operation command information, the electric power control device 12 sets the voltage applied to the battery 10 and the motor generator 14 so that electric power is supplied from the battery 10 to the motor generator 14. adjust. Further, the power control device 12 is applied to the battery 10 and the motor generator 14 so that power is supplied from the motor generator 14 to the battery 10 when the motor generator 14 generates regenerative braking torque based on the operation command information. Adjust the voltage.

  When electric power is supplied from the motor generator 14 to the battery 10, the battery 10 is charged. At this time, the power control device 12 adjusts the charging power supplied to the battery 10 so as not to exceed the charging power limit value Win output by the power limit value calculation device 24.

  The vehicle power control system includes a current sensor 18 that measures the current flowing through the battery 10, a voltage sensor 20 that measures the output voltage of the battery 10, and the battery 10, in order for the power limit value calculation device 24 to obtain the charging power limit value Win. The temperature sensor 22 which measures the temperature of is provided. The current sensor 18 outputs the measurement result as the battery current measurement value Ib to the power limit value calculation device 24, and the voltage sensor 20 outputs the measurement result as the battery voltage measurement value Vb to the power limit value calculation device 24. Further, the temperature sensor 22 outputs the measurement result to the power limit value calculation device 24 as the battery temperature measurement value Tb.

  Based on the battery current measurement value Ib, the battery voltage measurement value Vb, and the battery temperature measurement value Tb, the power limit value calculation device 24 calculates the charge power limit value Win and outputs it to the power control device 12.

  FIG. 2 shows the configuration of the power limit value calculation device 24 according to the first embodiment. In order to describe the process executed by the battery state quantity estimation unit 26, here, an example of an electrochemical model of the battery 10 will be described based on the content of Patent Document 2.

  The battery 10 can be configured by connecting a plurality of battery cells in series. FIG. 3 shows the configuration of the battery cell. The battery cell includes a negative electrode 40, a separator 44, and a positive electrode 42. The separator 44 is configured by infiltrating an electrolytic solution into a resin provided between the negative electrode 40 and the positive electrode 42.

The negative electrode 40 and the positive electrode 42 are composed of an aggregate of spherical active materials. On the interface of the active material 46 of the negative electrode 40, a chemical reaction that releases or absorbs lithium ions Li ⁺ and electrons e ⁻ is performed. On the other hand, a chemical reaction that absorbs or releases lithium ions Li ⁺ and electrons e ⁻ is performed on the interface of the active material 48 of the positive electrode 42.

The negative electrode 40 is provided with a negative electrode collector 50 that conducts electrons e ⁻ with the negative electrode terminal 54, and the positive electrode 42 is provided with a positive electrode collector 52 that conducts electrons e ⁻ with the positive electrode terminal 56. The metal material used for the negative electrode collector 50 and the positive electrode collector 52 is determined based on the magnitude relationship of the ionization tendency. Generally, the negative electrode collector 50 is made of copper, and the positive electrode collector 52 is made of aluminum.

When the lithium ions Li ⁺ are exchanged between the positive electrode 42 and the negative electrode 40 via the separator 44, the charging current flows out of the positive electrode terminal 56 and flows into the negative electrode terminal 54 via the external circuit 58 to the battery cell. Alternatively, a discharge current that flows out from the negative terminal 54 and flows into the positive terminal 56 through the external circuit 58 flows.

An electrochemical model of the battery cell will be described with reference to FIG. At the time of discharging, electrons e ⁻ are emitted from the active material 46 of the negative electrode 40 to the negative electrode collector 50, and the lithium atoms Li in the active material 46 of the negative electrode 40 become lithium ions Li ⁺ . At the same time, lithium ions Li ⁺ are released from the active material 46 of the negative electrode 40 to the electrolytic solution in the separator 44. The active material 48 of the positive electrode 42 takes in lithium ions Li ⁺ from the electrolytic solution, absorbs electrons e ⁻ from the positive electrode collector 52, and takes in lithium atoms Li inside the active material 48 of the positive electrode 42. As a result, a discharge current that flows out from the positive electrode collector 52 and flows into the negative electrode collector 50 through the external circuit 58 flows.

On the other hand, at the time of charging, electrons e ⁻ are released from the active material 48 of the positive electrode 42 to the positive electrode collector 52, and lithium ions Li ⁺ are released from the active material 48 of the positive electrode 42 to the electrolytic solution in the separator 44. The active material 46 of the negative electrode 40 takes in lithium ions Li ⁺ from the electrolytic solution, absorbs electrons e ⁻ from the negative electrode collector 50, and takes in lithium atoms Li inside the active material 46 of the negative electrode 40. As a result, a charging current that flows out from the negative collector 50 and flows into the positive collector 52 through the external circuit 58 flows.

  For the analysis of the electrochemical model, the electrode reaction on each surface of the active materials 46 and 48 during charge and discharge, the diffusion of lithium ions in each active material 46 and 48 in the radial direction, the lithium in the electrolyte A battery model formula for ion diffusion, potential distribution at each site, and the like is used. The battery model formula is expressed by the following formulas (M1) to (M15). Details of these equations are described in Non-Patent Document 1.

  FIG. 3 shows battery model parameters used in equations (M1) to (M15).

The formulas (M1) to (M3) are formulas indicating an electrode reaction, and are called Butler-Volmer formulas. In the equation (M1), the exchange current density i ₀ is given as a function of the lithium ion concentration at the interface of the active material (refer to Non-Patent Document 1 for details). Α _a represents the transfer coefficient of the electrode reaction at the positive electrode, and α _c represents the transfer coefficient of the electrode reaction at the negative electrode. The expression (M2) gives η in the expression (M1), and the expression (M3) gives U in the expression (M2).

Equations (M4) to (M6) represent the law of conservation of lithium ions in the electrolyte. The equation (M5) shows the definition of the effective diffusion coefficient in the electrolyte, and the equation (M6) shows that the reaction current j ^Li is the active material surface area a _s per unit volume of the electrode and the transport current shown in the equation (M1). It indicates that given by the product of the density / i _n. The volume integral of the reaction current j ^{Li over} the entire electrode corresponds to the current I flowing through the battery cell.

Equations (M7) and (M8) indicate the conservation law of lithium ions in the solid layer. (M7) equation represents the diffusion equation in an active material in the sphere shows (M8) expression per electrode unit volume active material surface area a _s.

  Expressions (M9) to (M11) are based on the law of conservation of charge in the electrolyte. These equations show the potential in the electrolyte.

The equation (M10) represents the effective ionic conductivity κ ^eff and the equation (M11) represents the diffusion conductivity coefficient κ _D ^eff in the electrolytic solution.

  Equations (M12) and (M13) are based on the law of conservation of charge in the active material. These formulas show the potential in the solid layer.

  Equations (M14) and (M15) are based on the thermal energy conservation law. By these equations, it becomes possible to analyze a local temperature change inside the battery due to a charge / discharge phenomenon.

  Since the battery model formulas (M1) to (M15) are based on Non-Patent Document 1, Non-Patent Document 1 is used for detailed description of each formula.

  The battery model parameters shown in FIG. 4 can be obtained by combining battery model expressions (M1) to (M15). That is, the unknown equation among the battery model parameters shown in FIG. 4 is obtained by sequentially solving the equation (M1) to (M15) so that the boundary condition is satisfied at each point in the active material and the electrolytic solution. Things can be calculated sequentially. In this case, which of the battery model parameters shown in FIG. 4 is a known amount and which is an unknown amount can be arbitrarily determined in the theory of numerical analysis. The lithium ion concentration in each active material is a function of the radius r of the active material, and the lithium ion concentration is treated as uniform in the circumferential direction.

The battery state quantity estimation unit 26 obtains the battery state quantity BS based on the battery current measurement value Ib, the battery voltage measurement value Vb, the battery temperature measurement value Tb, and the battery model parameter. Here, the battery state quantity BS includes, among the battery model parameters, the potential φ _s in the solid layer, the potential φ _e in the electrolytic solution, the lithium ion concentration c _s of the active material, the lithium ion concentration c _e of the electrolytic solution, and It is a physical stoichiometry comprising a set of lithium ion concentrations c _se at the active material interface.

The battery state quantity estimation unit 26 obtains a battery state quantity BS (φ _s , φ _e , c _s , c _e , and c _se ) based on the battery model equations (M1) to (M15), and the battery state quantity BS Is output to the first chargeable power prediction unit 28 and the second chargeable power prediction unit 36.

  The charge allowable current setting unit 30 determines a charge current limit value Ic when charging with a constant current and outputs the charge current limit value Ic to the first chargeable power prediction unit 28. Here, the charging current limit value is an arithmetic value set for calculation by the first chargeable power prediction unit 28.

  FIG. 5A shows an example of a waveform of the charging current limit value. The horizontal axis of Fig.5 (a) shows time, and a vertical axis | shaft shows a charging current limiting value. The charging current limit value shown in FIG. 5 (a) increases from the battery current measured value Ib to the charging current limit value Ic at the reference time t0.

The first chargeable power prediction unit 28 uses the battery state quantity BS and the battery temperature measurement value Tb as initial values, and changes the time change of the output voltage V of the battery 10 when the battery 10 is charged with a constant current at the charge current limit value Ic. Predict based on the formulas (M1) to (M15). At this time, the current given by the charging current limit value Ic is associated with the volume integration of the reaction current j ^{Li over} the entire electrode. Further, the output voltage V of the battery 10 is determined based on a well-known physical relationship established among the potential φ _s in the solid layer, the reaction current j ^Li , and the electron conductivity σ in the solid layer. The first chargeable power prediction unit 28 obtains a chargeable power characteristic indicating a change over time of the chargeable power based on the obtained voltage V and the charge current limit value.

  FIG. 5B shows an example of chargeable power characteristics obtained by the first chargeable power prediction unit 28 based on the charging current shown in FIG. In FIG. 5B, the horizontal axis indicates time, and the vertical axis indicates chargeable power. In this example, the value indicated by the chargeable power characteristic increases with time.

  On the other hand, the allowable charging voltage setting unit 34 outputs a constant charging voltage limit value Vc to the second chargeable power prediction unit 36 and the selection unit 32. Here, the charge voltage limit value is an arithmetic value set for processing of the second chargeable power prediction unit 36 and the selection unit 32.

  FIG. 6A shows a time waveform of the charging voltage limit value. In FIG. 6A, the horizontal axis indicates time, and the vertical axis indicates the charging voltage limit value. The charging voltage limit value has a constant value Vc.

The second chargeable power predicting unit 36 uses the battery state quantity BS and the battery temperature measurement value Tb as initial values, and changes the time change of the current I flowing through the battery 10 when constant voltage charging is performed with the charge voltage limit value Vc ( Predict based on the formulas (M1) to (M15). At this time, a well-known physical relationship established among the charge voltage limit value, the potential φ _s in the solid layer, the reaction current j ^Li , and the electron conductivity σ in the solid layer is used. The current I is obtained based on the volume integration of the reaction current j ^{Li over} the entire electrode. The second rechargeable power prediction unit 36 obtains a rechargeable power characteristic indicating a change over time of the rechargeable power based on the obtained current I and the charge voltage limit value. The second chargeable power prediction unit 36 outputs chargeable power characteristic data to the selection unit 32.

  FIG. 6B shows an example of the chargeable power characteristic obtained by the second chargeable power prediction unit 36 based on the charge voltage limit value shown in FIG. In FIG. 6B, the horizontal axis indicates time, and the vertical axis indicates chargeable power. In this example, the value indicated by the chargeable power characteristic decreases with time.

  The selection unit 32 compares the battery voltage measurement value Vb with the charge voltage limit value Vc. Then, when the battery voltage measurement value Vb is less than the charge voltage limit value Vc, a value given by the chargeable power characteristic output by the first chargeable power prediction unit 28 is output as the charge power limit value Win. On the other hand, when the battery voltage measurement value Vb reaches the charge voltage limit value Vc, the selection unit 32 outputs the value given by the chargeable power characteristic output by the second chargeable power prediction unit 36 as the charge power limit value Win. To do. The power control device 12 controls the charging of the battery 10 so as not to exceed the charging power limit value Win.

  In the configuration illustrated in FIG. 2, the charge power limit value Win may be a value that is greater than or equal to the allowable power of the circuit that charges the battery 10. Therefore, a power limit value setting unit 38 may be provided as in the second embodiment shown in FIG. The same components as those shown in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  The power limit value setting unit 38 obtains the charge power limit value Win based on the chargeable power characteristic data output from the selection unit 32. Here, it is assumed that the power limit value setting unit 38 stores a predetermined Win calculation time tc for obtaining the charge power limit value in advance. The power limit value setting unit 38 refers to the chargeable power characteristic data, and obtains the chargeable power when the Win calculation time tc has elapsed from the reference time t0 as the charge power limit value Win. The power limit value setting unit 38 outputs the charging power limit value Win to the power control device 12.

  When the chargeable power characteristic data output by the first chargeable power prediction unit 28 is output to the power limit value setting unit 38, as shown in FIG. 5B, the time for Win calculation tc from the reference time t0. The value on the vertical axis when the time elapses is obtained as the charging power limit value Win. In addition, when the chargeable power characteristic data output from the second chargeable power prediction unit 36 is output to the power limit value setting unit 38, as shown in FIG. The value on the vertical axis when the time tc has elapsed is obtained as the charging power limit value Win.

  The power limit value calculation device 24 performs processing for obtaining the charge power limit value Win every predetermined time Td, and outputs the charge power limit value Win to the power control device 12 at a time interval Td. The power control device 12 controls the charging of the battery 10 so as not to exceed the charging power limit value Win.

  By making the Win calculation time tc longer than the time interval Td for obtaining the charging power limit value Win, the time from each calculation time point depends on the battery state quantity BS and the battery temperature measurement value Tb of the battery 10 that change every moment. The charging power limit value Win ahead by tc can be determined adaptively. As a result, the battery 10 can be charged with as much power as possible according to the battery state quantity BS and the battery temperature measurement value Tb of the battery 10.

  The value indicated by the chargeable power characteristic by the first chargeable power prediction unit 28 increases as the charging current limit value Ic increases, and the required charging power limit value Win increases. Further, as shown in FIG. 5B, the value indicated by the chargeable power characteristic increases as the Win calculation time tc increases, and the required charging power limit value Win increases.

  Further, the value indicated by the chargeable power characteristic by the second chargeable power prediction unit 36 increases as the charge voltage limit value Vc increases, and the required charge power limit value Win increases. Further, as shown in FIG. 6B, the value indicated by the chargeable power characteristic increases as the Win calculation time tc is shortened, and the required charging power limit value Win increases.

  Here, the time required to charge the battery to a predetermined charging depth is shorter as the charging power is larger, while the battery life defined by a period in which a charging capacity of a predetermined value or more can be maintained is the charging power. The larger the size, the shorter. Therefore, it is preferable that the charging current limit value Ic, the charging voltage limit value Vc, and the Win calculation time tc are determined based on experiments or the like in view of the life of the battery 10 and the quickness of the charging time.

  According to such a configuration, when the battery 10 is being charged, if the output voltage of the battery 10 is less than the charging voltage limit value Vc, the chargeable power output from the first chargeable power prediction unit 28 is possible. Based on the power characteristic data, charging power limit value Win is obtained. On the other hand, when the output voltage of the battery 10 reaches the charge voltage limit value Vc, the charge power limit value Win is obtained based on the chargeable power characteristic data output by the second chargeable power prediction unit 36.

  That is, until the output voltage of the battery 10 reaches the charging voltage limit value Vc, the battery 10 is charged by using the current of the charging current limit value Ic as the charging current, thereby obtaining the charging power limit value Win. 10 can be reduced. On the other hand, after the output voltage of the battery 10 reaches the charging voltage limit value Vc, the charging power limit value Win is determined as much as possible by determining that the battery 10 is charged while the output voltage is maintained at the charging voltage limit value Vc. The battery 10 can be charged with a large charge power and can be quickly charged. Thereby, it is possible to perform quick charging while suppressing an electrical load on the battery 10.

  It should be noted that examples of time waveforms of the battery current measurement value Ib, the battery voltage measurement value Vb, and the chargeable power when the selection state in the selection unit 32 is switched while one chargeable power characteristic is obtained are respectively 8 (a), (b) and (c). These figures show the case where the battery voltage measurement value Vb is less than the charging voltage limit value from the reference time t0 to the time t1, and the battery voltage measurement value Vb reaches the charging voltage limit value after the time t1.

  FIG. 9 shows the configuration of the power limit value calculation device 24 according to the third embodiment. In this embodiment, the allowable charging voltage setting unit 60 determines the charging voltage limit value Vc based on the battery state quantity BS, and the allowable charging current setting unit 30 determines the charging current limit value Ic based on the battery state quantity BS. . The same components as those of the second embodiment shown in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted.

  The battery state quantity estimation unit 26 calculates the charge depth of the battery 10 obtained from the battery state quantity BS and the battery state quantity BS by a first chargeable power prediction unit 28, a second chargeable power prediction unit 36, and a charge allowable current setting unit 30. And output to the charge allowable voltage setting unit 60. The allowable charging voltage setting unit 60 obtains the charging depth of the battery 10 based on the battery state quantity BS using the equations (M1) to (M15). Here, the charge depth refers to an amount indicating the ratio of the charge amount currently charged to the charge amount at the time of full charge. In the electrochemical model, the charging depth can be obtained from the number of lithium atoms in the active material 46 of the negative electrode 40.

  The charge allowable current setting unit 30 stores a charge depth versus current limit value table in which the charge depth and the charge current limit value Ic are associated with each other, and the charge allowable voltage setting unit 60 stores the charge depth and the charge voltage limit value Vc. The associated charge depth vs. voltage limit value table is stored. The allowable charging current setting unit 30 and the allowable charging voltage setting unit 60 refer to these tables to obtain the charging current limit value Ic and the charging voltage limit value Vc corresponding to the charging depth.

  The chargeable current setting unit 30 outputs the charge current limit value Ic to the first chargeable power prediction unit 28, and the charge allowable voltage setting unit 60 selects the charge voltage limit value Vc and the second chargeable power prediction unit 36 and the selection. To the unit 32.

  In FIG. 10, the example of the relationship which a charging depth vs. current limiting value table shows is shown with a graph. The horizontal axis of FIG. 10 indicates the charging depth, and the vertical axis indicates the charging current limit value Ic. In the example of FIG. 10, when the charging depth is less than the predetermined threshold SOCt, the charging current limit value Ic is constant with respect to the change in the charging depth. On the other hand, when the charging depth is equal to or greater than the predetermined threshold SOCt, the charging depth increases and the charging current limit value Ic is decreased.

  When there is a relationship SOCt <SOC1 <SOC2 between the charging depths SOC1 and SOC2, the relationship between the charging current limit values Ic1 and Ic2 corresponding to each is Ic1> Ic2. As a result, the time waveform of the charge current limit value indicated by the charge current limit value / time waveform data output by the charge allowable current setting unit 30 is the time waveform 62-1 and 62-2 of FIG. It becomes like this. Then, corresponding to the time waveforms 62-1 and 62-2 in FIG. 11A, the chargeable power characteristics obtained by the first chargeable power prediction unit 28 are the characteristics 64- in FIG. 11B, respectively. 1 and 64-2. From the characteristics 64-1 and 64-2, charging power limit values Win1A and Win2A are obtained for the Win calculation time tc, respectively. These charging power limit values have a relationship of Win1A> Win2A.

  FIG. 12 is a graph showing an example of the relationship indicated by the charging depth versus voltage limit value table. The horizontal axis of FIG. 12 indicates the charging depth, and the vertical axis indicates the charging voltage limit value Vc. In the example of FIG. 12, when the charging depth is less than the predetermined threshold SOCt, the charging voltage limit value Vc is fixed with respect to the change in the charging depth. On the other hand, when the charging depth is equal to or greater than the predetermined threshold SOCt, the charging depth is increased and the charging voltage limit value Vc is decreased.

  The relationship between the charging voltage limit values Vc1 and Vc2 corresponding to the charging depths SOC1 and SOC2 is Vc1> Vc2. As a result, the time waveforms of the charge voltage limit value output by the charge allowable current setting unit 30 are as shown by time waveforms 66-1 and 66-2 in FIG. Then, corresponding to the time waveforms 66-1 and 66-2 in FIG. 13A, the chargeable power characteristics obtained in the second chargeable power prediction unit 36 are the characteristics 68- in FIG. 13B, respectively. 1 and 68-2. From the characteristics 68-1 and 68-2, charging power limit values Win1B and Win2B are obtained for the Win calculation time tc, respectively. These charging power limit values have a relationship of Win1B> Win2B.

  Examples of respective time waveforms of the battery current measurement value Ib, the battery voltage measurement value Vb, and the chargeable power when the selection state in the selection unit 32 is switched in the middle of obtaining one chargeable power characteristic are shown in FIG. 14 (a), (b) and (c). These figures show the case where the battery voltage measurement value Vb is less than the charging voltage limit value from the reference time t0 to the time t1, and the battery voltage measurement value Vb reaches the charging voltage limit value after the time t1. Characteristics 70-1 and 70-2 before time t1 in FIG. 14C correspond to characteristics 64-1 and 64-2 in FIG. 11B, respectively. Characteristics 72-1 and 72-2 after time t1 in FIG. 14C correspond to characteristics 68-1 and 68-2 in FIG. 13B, respectively.

  Thus, in this embodiment, the charge allowable voltage setting unit 60 determines that the charge current limit value Ic and the charge voltage limit value are such that the value decreases as the charge depth increases when the charge depth exceeds a predetermined threshold. Vc is determined. As a result, when the charging depth becomes equal to or greater than a predetermined threshold, the charging power limit value Win can be reduced as the charging depth increases.

  In general, batteries often do not require quick charging when the charging depth is large. Therefore, according to the present embodiment, when the charging depth is equal to or greater than the predetermined threshold value, the charging power can be reduced and the electrical burden on the battery 10 can be reduced.

  Here, the processing using the charging depth has been described, but the same processing can be performed using other amounts indicating the charging state of the battery 10 that can be obtained from the battery state amount BS.

  FIG. 15 shows the configuration of a vehicle power control system according to another embodiment of the present invention. The same components as those of the vehicle power control system of FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The battery diagnosis / power limit value calculation device 76 changes the current flowing through the battery 10 in the battery diagnosis mode, and determines the battery model parameters of the battery 10, the degree of deterioration of the battery 10, etc. based on the change in the output voltage of the battery 10. Ask. Then, the charging power limit value Win is obtained from the equations (M1) to (M15) using the obtained battery model parameters, the degree of deterioration, and the like.

FIG. 16 shows the configuration of the battery diagnosis / power limit value calculation device 76 according to the first embodiment. The same components as those of the power limit value calculation device 24 shown in FIG. This embodiment includes a battery characteristic determination unit 78 that measures the exchange current density i ₀ and the diffusion coefficient D _s of the battery 10.

  A mode changeover switch 74 is connected to each end of the battery 10. The mode changeover switch 74 connects the battery 10 to the power control device 12 in the normal travel mode. On the other hand, in the battery diagnosis mode, the battery 10 is connected to the battery diagnosis / power limit value calculation device 76. In the battery diagnosis mode, the battery diagnosis / power limit value calculation device 76 controls the current flowing through the battery 10 so that the time waveform of the current flowing through the battery 10 becomes, for example, the time waveform shown in FIG. . In FIG. 17A, the horizontal axis indicates time, and the vertical axis indicates the charging current flowing through the battery 10. The current time waveform in FIG. 17A changes from the initial value I1 at which the charging current of the battery 10 is at the diagnostic current value I2 at time t1, and then maintains the diagnostic current value I2 until time t2, and then returns to the initial value I1. FIG. 17B shows an example of a time waveform of the battery voltage measurement value Vbp at this time. The horizontal axis represents time, and the vertical axis represents the measured battery voltage value Vbp.

The battery characteristic determining unit 78 is based on the time variation of the battery voltage measurement value Vbp, the battery current measurement value Ibp, and the battery temperature measurement value Tbp when the current of the battery 10 changes as shown in FIG. Among the battery model parameters listed in FIG. 4, the exchange current density i ₀ and the diffusion coefficient D _s are obtained.

The battery characteristic determination unit 78 outputs the obtained exchange current density i ₀ and the diffusion coefficient D _s to the battery state quantity estimation unit 26, the first chargeable power prediction unit 28, and the second chargeable power prediction unit 36. .

The battery state quantity estimation unit 26 updates the exchange current density i ₀ and the diffusion coefficient D _s previously used to the exchange current density i ₀ and the diffusion coefficient D _s newly given from the battery characteristic determination unit 78, The battery state quantity BS is obtained. The first chargeable power prediction unit 28 and the second chargeable power prediction unit 36 use the exchange current density i ₀ and the diffusion coefficient D _s previously used as the exchange current density newly given from the battery characteristic determination unit 78. The chargeable power characteristic is obtained by updating to i ₀ and the diffusion coefficient D _s .

According to this embodiment, even when the exchange current density i ₀ and the diffusion coefficient D _s of the battery 10 changes due to aging or the like, suitably using an exchange current density i ₀ and the diffusion coefficient D _s after the change Charge control can be performed.

  The processing in the battery diagnosis mode is preferably performed when the vehicle is stopped with the vehicle power control system operable, such as when the ignition is on.

  FIG. 18 shows a configuration of a battery diagnosis / power limit value calculation device 76 according to the second embodiment. In this embodiment, the deterioration degree estimation unit 80 obtains the deterioration degree of the battery 10 based on the measured battery current Ibp, the measured battery voltage Vbp, and the measured battery temperature Tbp in the battery diagnosis mode, and the charge allowable current setting unit 30 and This is output to the charge allowable voltage setting unit 82. Charging allowable current setting unit 30 obtains charging current limit value Ic based on the degree of deterioration, and outputs it to first chargeable power prediction unit 28. Charging allowable voltage setting unit 82 obtains charging voltage limit value Vc based on the degree of deterioration, and outputs it to second chargeable power prediction unit 36 and selection unit 32. The same components as those of the first embodiment shown in FIG. 16 are denoted by the same reference numerals and description thereof is omitted.

  The battery diagnosis / power limit value calculation device 76 controls the current flowing through the battery 10 so that the time waveform of the current flowing through the battery 10 becomes, for example, the time waveform shown in FIG. Deterioration degree estimation unit 80 determines the degree of deterioration of battery 10 based on measured battery voltage Vbp, battery current measurement value Ibp, and battery temperature measurement value Tbp when the current of battery 10 changes as shown in FIG. Ask. Here, the deterioration degree of the battery 10 can be evaluated by, for example, SOH (State Of Health). SOH is defined as the ratio of the current chargeable discharge amount at full charge to the chargeable charge amount (full chargeable charge amount) when the battery is fully charged when new. The SOH can be obtained by referring to a table in which the relationship between the value of the battery model parameter and the SOH is determined by experiments or the like. The deterioration degree estimation unit 80 outputs the obtained deterioration degree to the charge allowable voltage setting unit 82.

  The allowable charge current setting unit 30 stores a deterioration degree vs. current limit value table in which the deterioration degree and the charge current limit value Ic are associated with each other. The allowable charge voltage setting unit 82 stores the deterioration degree and the charge voltage limit value Vc. The associated deterioration degree versus voltage limit value table is stored. The allowable charging current setting unit 30 and the allowable charging voltage setting unit 82 refer to these tables to determine the charging current limit value Ic and the charging voltage limit value Vc corresponding to the obtained degree of deterioration.

  Charging allowable current setting unit 30 outputs charging current limit value Ic to first chargeable power prediction unit 28, and charging allowable voltage setting unit 82 selects charging voltage limit value Vc and second chargeable power prediction unit 36 and selection. To the unit 32.

  FIG. 19 is a graph showing an example of the relationship indicated by the deterioration degree vs. current limit value table. The horizontal axis in FIG. 19 indicates the degree of deterioration, and the vertical axis indicates the charging current limit value Ic. In the example of FIG. 19, when the degree of deterioration is less than a predetermined threshold value Ht, the charging current limit value Ic is constant with respect to the change in the degree of deterioration. On the other hand, when the deterioration level is equal to or higher than the predetermined threshold Ht, the deterioration level increases and the charging current limit value Ic is decreased.

  When there is a relationship of Ht <H3 <H4 between the degradation levels H3 and H4, the relationship between the charging current limit values Ic3 and Ic4 corresponding to each is Ic3> Ic4. As a result, the time waveforms of the charge current limit values output by the charge allowable current setting unit 30 are as shown by time waveforms 84-3 and 84-4 in FIG. And the chargeable power characteristic calculated | required in the 1st chargeable electric power estimation part 28 corresponding to the time waveforms 84-3 and 84-4 of Fig.20 (a) is respectively the characteristic 86- of FIG.20 (b). 3 and 86-4. From the characteristics 86-3 and 86-4, charging power limit values Win3A and Win4A are obtained for the time tc for Win calculation, respectively. These charging power limit values have a relationship of Win3A> Win4A.

  FIG. 21 is a graph showing an example of the relationship indicated by the deterioration degree vs. voltage limit value table. The horizontal axis in FIG. 21 indicates the degree of deterioration, and the vertical axis indicates the charging voltage limit value Vc. In the example of FIG. 21, when the degree of deterioration is less than a predetermined threshold value Ht, the charging voltage limit value Vc is fixed with respect to the change in the degree of deterioration. On the other hand, when the degree of deterioration is equal to or greater than the predetermined threshold Ht, the degree of deterioration increases and the charge voltage limit value Vc is decreased.

  The relationship between the charging voltage limit values Vc3 and Vc4 corresponding to the deterioration levels H3 and H4 is Vc3> Vc4. The time waveforms of the charging voltage limit value are as shown by time waveforms 88-3 and 88-4 in FIG. Then, corresponding to the time waveforms 88-3 and 88-4 in FIG. 22A, the chargeable power characteristics obtained in the second chargeable power prediction unit 36 are characteristics 90- in FIG. 22B, respectively. 3 and 90-4. From the characteristics 90-3 and 90-4, the charging power limit values Win3B and Win4B are obtained for the Win calculation time tc, respectively. These charging power limit values have a relationship of Win3B> Win4B.

  Examples of time waveforms of the battery current measurement value Ib, the battery voltage measurement value Vb, and the chargeable power when the selection state in the selection unit 32 is switched while one chargeable power characteristic is obtained are shown in FIG. Since it becomes the same as a), (b), and (c), FIG. 14 is used here. Characteristics 70-1 and 70-2 before time t1 in FIG. 14C correspond to characteristics 86-3 and 86-4 in FIG. The characteristics 72-1 and 72-2 after the time t1 in FIG. 14C correspond to the characteristics 90-3 and 90-4 in FIG.

  Thus, in the present embodiment, the charge allowable current setting unit 30 and the charge allowable voltage setting unit 82 limit the charging current so that the larger the deterioration level, the smaller the value when the deterioration level exceeds a predetermined threshold. A value Ic and a charging voltage limit value Vc are obtained. As a result, when the degree of deterioration exceeds a predetermined threshold, the charging power limit value Win can be reduced as the degree of deterioration increases.

  It is preferable to extend the life of the battery as much as possible without performing quick charging when the degree of deterioration increases. According to the present embodiment, when the degree of deterioration is equal to or greater than a predetermined threshold, the charging power can be reduced and the life of the battery 10 can be extended.

  16 and FIG. 18, respectively, the battery diagnosis / power limit value calculation device 76 according to the first and second embodiments is similar to the power limit value calculation device 24 shown in FIG. It is good also as a structure which does not use 38.

  DESCRIPTION OF SYMBOLS 10 Battery, 12 Power control apparatus, 14 Motor generator, 16 Operation part, 18 Current sensor, 20 Voltage sensor, 22 Temperature sensor, 24 Power limit value calculating apparatus, 26 Battery state quantity estimation part, 28 1st chargeable electric power estimation part , 30 Charging allowable current setting unit, 32 selection unit, 34 charging allowable voltage setting unit, 36 second chargeable power prediction unit, 38 power limit value setting unit, 40 negative electrode, 42 positive electrode, 44 separator, 46, 48 active material, 50 negative electrode collector, 52 positive electrode collector, 54 negative electrode terminal, 56 positive electrode terminal, 58 external circuit, 60, 82 charge allowable voltage setting unit, 62-1, 62-2, 84-3, 84-4 charge current limit value time waveform 64-1, 64-2, 68-1, 68-2, 70-1, 70-2, 72-1, 72-2, 86-3, 86-4, 90-3, 9 0-4 Chargeable power time waveform, 66-1, 66-2, 88-3, 88-4 Charging voltage limit value time waveform, 74 mode changeover switch, 76 battery diagnosis / power limit value calculation device, 78 battery characteristic determination Part, 80 Degradation degree estimation part.

Claims (10)

In a charging power limit value calculating device for determining a charging power limit value for a vehicle driving power supply battery,
A use state detection unit for detecting a power transfer state of the battery;
Based on the detection result of the use state detection unit, a battery state amount estimation unit for obtaining a battery state amount;
A first chargeable power prediction unit that obtains a charge current limit value and obtains chargeable power when the battery is charged with the current of the charge current limit value based on the battery state quantity;
A second chargeable power prediction unit that obtains a charge voltage limit value, and obtains chargeable power when the battery is charged with the voltage of the charge voltage limit value based on the battery state quantity;
The output voltage of the battery and the charge voltage limit value are compared, and the chargeable power obtained by the first chargeable power prediction unit or the charge obtained by the second chargeable power prediction unit according to the comparison result A selection unit that selects any one of the possible powers and obtains a chargeable power characteristic indicating a change over time of the chargeable power based on the selection result;
With
A charging power limit value calculation device that outputs a charging power limit value based on the chargeable power characteristic. In the charging power limit value calculation device according to claim 1,
A charging power limit value calculation device comprising: a power limit value setting unit that obtains chargeable power as a charging power limit value when a predetermined time has elapsed from a reference time based on the chargeable power characteristic. In the charging power limit value calculation device according to claim 1 or 2,
The selection unit includes:
When the output voltage of the battery is less than the charging voltage limit value, the charging power limit value calculating device is configured to select the chargeable power obtained by the first chargeable power prediction unit. In the charging power limit value calculation device according to any one of claims 1 to 3,
Based on the detection result of the use state detection unit, a deterioration degree estimation unit for obtaining a deterioration degree of the charging capacity of the battery,
An allowable current setting unit that determines a smaller charging current limit value as the degree of deterioration obtained by the deterioration degree estimating unit is larger, and gives the determined charging current limit value to the first chargeable power prediction unit;
A charging power limit value calculation device comprising: In the charging power limit value calculation device according to any one of claims 1 to 3,
Based on the detection result of the use state detection unit, a deterioration degree estimation unit for obtaining a deterioration degree of the charging capacity of the battery,
An allowable voltage setting unit that determines a smaller charging voltage limit value as the degree of deterioration obtained by the deterioration degree estimating unit is larger, and gives the determined charging voltage limit value to the second chargeable power prediction unit;
A charging power limit value calculation device comprising: In the charging power limit value calculation device according to claim 5,
An allowable current setting unit that determines a smaller charging current limit value as the degree of deterioration obtained by the deterioration degree estimating unit is larger, and gives the determined charging current limit value to the first chargeable power prediction unit;
A charging power limit value calculation device comprising: In the charging power limit value calculation device according to any one of claims 1 to 3,
The charge depth of the battery is determined based on the battery state quantity, the smaller the obtained charge depth, the smaller the charge current limit value is determined, and the predetermined charge current limit value is given to the first chargeable power predicting unit Current setting section,
A charging power limit value calculation device comprising: In the charging power limit value calculation device according to any one of claims 1 to 3,
The charging depth of the battery is determined based on the battery state quantity, the charging voltage limit value is set to be smaller as the determined charging depth is larger, and the predetermined charging voltage limit value is given to the second chargeable power prediction unit Voltage setting section,
A charging power limit value calculation device comprising: In the charging power limit value calculation device according to claim 8,
The charge depth of the battery is determined based on the battery state quantity, the smaller the obtained charge depth, the smaller the charge current limit value is determined, and the predetermined charge current limit value is given to the first chargeable power predicting unit Current setting section,
A charging power limit value calculation device comprising: The charging power limit value calculation device according to any one of claims 1 to 9,
A battery current controller for changing the current flowing through the battery;
A battery characteristic determination unit for obtaining a characteristic constant of the battery based on a change in the output voltage of the battery with respect to a current change by the battery current control unit;
With
The battery state quantity estimator is
Obtaining the battery state quantity based on the specific constant obtained by the battery characteristic determination unit,
The first and second chargeable power prediction units are
A charge power limit value calculation device characterized in that chargeable power is obtained based on a specific constant obtained by the battery determination unit.

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