JP6324332B2 - Charge / discharge control device and control method for lithium ion battery - Google Patents

Description

  The present invention relates to charging / discharging control of a lithium ion battery that controls charging to the lithium ion battery and discharging from the lithium ion battery by using physical variables of the charging voltage, charging current, discharging voltage, and discharging current of the lithium ion battery. The present invention relates to an apparatus and a control method.

FIG. 20 shows a general state in which the battery potential V _B changes in accordance with the state of charge (SOC) of a lithium ion battery (hereinafter referred to as LIB). (Hereinafter Qsoc-V _B curve). The state of charge SoC expresses the degree of the remaining capacity with respect to the capacity at the time of full charge as a percentage. For example, when the charge remaining capacity is half of that at the time of full charge, it is called SoC 50%.
In the curve of FIG. 20, in particular, the partial potential region (R1) where SoC is around 40% is flat, so that the potential dependency of the remaining charge is small. The LIB is stressed in the charge storage and charge and discharge are repeated from immediately after production, capacity decrease, it is accompanied not Qsoc-V _B curve degradation such as the internal resistance increases, or the leakage current increase varies. This hinders estimation of the remaining charge from the battery potential, and makes charge / discharge management by the conventional voltage control method difficult.

In general, when charging and discharging are used repeatedly, the number of repeated cycles is limited. The number of cycles in which 100% charge and 0% discharge are repeatedly used and the battery voltage drops to 80% is the LIB cycle number limit (hereinafter referred to as F _100% ), and is usually 500 to 1000 times. If this number of times is completed, it can be said that the optimum number of cycles has been reached, but the actual number of times of use is further increased because recharging is performed without actually using up to 0%.
There is a problem that the full charge (hereinafter referred to as SoC 100%) potential set at the time of such many charging changes due to subsequent charge / discharge cycle deterioration, and the potential starting point is not constant. In addition, LIBs in a highly charged state have a risk of overcharge due to deterioration over time of storage performance, circuit controllability, and thermal environment factors. Similarly, in the case of storing LIB, the charge potential is preferably low SoC than high SoC (high charge state including full charge), but if it is lowered too low to 2.4 V, an overdischarge risk occurs. In this case, the storage potential is empirically said to be around 3V.

Specifically, three examples relating to a conventional charge / discharge control method and apparatus for controlling LIB are listed below.
Discharge control characteristic diagram of a conventional first example shown in FIG. 21, the characteristics of the battery voltage V _B with respect to FIG. 21 (a) the external load varies, FIG. 21 (b) remaining charge to the external load changes SoC The characteristics of In FIG. 21, a sufficient amount of charge including full charge is charged each time, and is always set to a high potential state at the start of discharge. In this case, the depth of discharge (DoD) management is required to prevent overdischarge due to heavy load or long-time use. The discharge depth DoD refers to the degree of discharge amount, and this discharge amount is calculated from the discharge time and the discharge current.
As a second conventional example, there is an example of charge / discharge control using the LIB charge amount as a control amount (see Patent Documents 1 and 2). Figure 22 is a double-charged potential of the end potential Vec and discharge end voltage Ved acquired during cycle, a _{SoC-V B} characteristic diagram plotting the set potential of a predetermined upper limit potential Vhigh and the lower limit electric potential Vlow.

Here, the discharge amount obtained in the discharge period is used as the supplement amount, and the same amount is charged in the charge period of the next cycle. The supplement amount is not constant and is determined depending on the external load. Further, self-discharge loss and the like are supplemented by voltage control as an adjustment amount. In the conventional method, the potential difference w1 (difference between the upper limit potential Vhigh and the charge end potential Vec) and the potential difference w2 (difference between the lower limit potential Vlow and the discharge end potential Ved) shown in FIG. 22 are converted into a charge correction amount. To do.
The conventional third charge / discharge control example performs charge control at low SoC (0.5 or less), which is advantageous from the viewpoint of charge / discharge cycle deterioration.

US Pat. No. 6,204,634 B1 Japanese Patent No. 3767378

The technical problem of the example regarding the method and means of the charge / discharge control for the conventional LIB will be described below.
In the first conventional example, the discharge start voltage at each cycle is charged to a high charge potential including full charge so as to respond to an unexpected heavy load. Here, even if the battery potential V _B is slightly lowered from 4.2 V to 4.1 V, as long as the high charge state is maintained, there is a risk of deterioration and overcharge risk.
When the depth of discharge DoD is shallow, external discharge starts from the full charge potential every cycle, and as a result, the average charge remaining amount remains high.

The problems of the first conventional example are summarized as follows.
a) When discharging starts from full charge, the discharge current characteristics in FIG. 21 are in a disadvantageous condition for battery deterioration because of the high average charge remaining value in the charge / discharge cycle.
b) The accumulated amount of charge is closely related to the deterioration, and keeping the average charge remaining amount during the charge / discharge cycle period high causes the deterioration due to charge accumulation to proceed.
c) Leaving a LIB under conditions of no load or infrequent use in a fully charged state for a long period of time increases the risk of overcharging that could cause battery smoke or ignition due to changes in the peripheral control circuit or thermal environment. Bear. During the charge / discharge cycle, full charge management with a high overcharge risk needs to be performed more strictly.

In the second conventional example, the average charge amount in the charge / discharge cycle is set to a medium potential, for example, 3.7 V to 3.9 V, and then the charge corresponding to the charge amount discharged in the discharge period is charged in the charge period. In addition, adjustment by partial voltage control is performed in order to correct the capacity loss due to self-discharge or the like. However, since the Qsoc-V _B curve is changed during the charge / discharge cycle, it is difficult to maintain and control the battery potential V _B at a predetermined value. Figure 23 shows the voltage dependence of the battery capacity change rate calculated from _{Qsoc-V B} curve of FIG. 20. Figure 23 is the battery capacity change rate with respect to the battery voltage V _B change is nonlinear, there is a sensitivity difference of seven times depending on the value of the cell potential V _B.

In the example of charge / discharge control according to the third conventional example, when the control potential of the charge / discharge cycle is set to a low SoC value, that is, a low voltage range, there is the following problem.
(A) When a battery is used at a low SoC, the internal resistance is large, which causes a temperature increase due to self-heating. This temperature rise is a cause of thermal degradation.
(B) Since the battery potential always changes in the low voltage region, the control range is clearly narrow and the control width is small. In the event of an unexpected heavy load, overdischarge may occur.
(C) If there is free battery capacity by low SoC control, the cost efficiency is not high in terms of power consumption to weight ratio.

The present invention has been made to solve the above-described problems. Even when the LIB Qsoc-V _B curve is deteriorated over time, the charge amount can be stably controlled, and the risk of overcharge and overdischarge is avoided. It is an object to obtain a charge / discharge control device and control method for a lithium ion battery.

A charge / discharge control device for a lithium ion battery according to the present invention includes a control unit including a discharge current input unit, a charge current output unit, and a timer scheduler, and receives a supply current from an external power source by a control signal from the control unit. A charging / discharging processing unit for forming a charging circuit for charging the ion battery and a discharging circuit for outputting a discharging current from the lithium ion battery to an external load, and the discharging current input unit sets the discharging period of the lithium ion battery to two sections A discharge potential discriminating unit for calculating a first discharge charge amount Q1 measured in the previous period and a second discharge charge amount Q2 measured in the latter period based on a predetermined equilibrium potential for discrimination, and a load state at the time of discharge The discharge current determination unit includes a first discharge charge amount Q1 and a second discharge charge amount Q2 from the discharge current input unit, and a load state from the discharge state determination unit. Accordance those for calculating the charge amount Q of the next cycle.
Q = K1 × Q1 + K2 × Q2
However, the coefficients K1 and K2 are different values depending on the load state.

The charge / discharge control method for a lithium ion battery according to the present invention controls switching between a charge circuit that charges a lithium ion battery in response to a supply current from an external power supply and a discharge circuit that outputs a discharge current from the lithium ion battery to an external load. In addition, in a charge / discharge control method for a lithium ion battery that controls charging according to the discharge amount of the lithium ion battery, the discharge period of the lithium ion battery is distinguished into two sections based on a predetermined equilibrium potential. The first discharge charge amount Q1 measured and the second discharge charge amount Q2 measured late are calculated, the load state at the time of discharge is determined, and the first discharge charge amount Q1 and the second discharge charge amount Q2 are determined. From the load state at the time of discharging, the charge amount Q of the next cycle is calculated according to the following equation.
Q = K1 × Q1 + K2 × Q2
However, the coefficients K1 and K2 are different values depending on the load state.

The present invention discriminates two stored charge amounts obtained by separating and measuring the discharge amount of the lithium ion battery into two, and discharge load states, for example, a light load, a heavy load and a steady load. Since the algorithm for calculating the charge amount in the next cycle from the two accumulated charge amounts and the load state is adopted, there is an effect that the charge amount can be stably controlled even when the LIB Qsoc-V _B curve is deteriorated with time.
Further, by performing charge amount control using a cycle average charge amount different from that of the conventional method, the average potential of LIB can always be set to a middle potential, and there is an effect that can be avoided from overcharge and overdischarge risks. In addition, the cycle average charge amount is automatically controlled so as to follow the fluctuations in the discharge load, so that the excessive amount of the stored amount can be thoroughly eliminated and the storage deterioration due to the higher charge can be alleviated. .

Furthermore, while the conventional example uses a simple full charge potential and a low SoC region, in the present invention, the discharge load control is performed using the cycle average charge amount at the time of charge / discharge as the control amount. In addition, by adjusting the average charge amount to a lower value so as to relieve the battery-related battery stress, there is an effect of reducing the capacity deterioration caused by the charge amount in the charge / discharge cycle, storage and standby.
Since the average charge amount during the charge / discharge cycle is set to the middle in terms of potential, the battery container suddenly expands with heat generation, and the subsequent safety valve opens, and the charge amount exceeds 100%. In addition, there is an effect that it is possible to avoid overcharge and overdischarge risk for a battery in a charge / discharge state of less than 0%.

It is a schematic diagram of the charging / discharging control apparatus of the lithium ion battery of this invention. It is a functional block diagram of the charging / discharging control apparatus of the lithium ion battery in Embodiment 1 of this invention. It is a specific block diagram of the discharge current input part used for the charging / discharging control apparatus shown by FIG. It is a figure which shows the relative relationship of the control potential of 3 patterns by a discharge load state. It is a specific block diagram of the charging current output part used for the charging / discharging control apparatus shown by FIG. It is a schematic diagram which shows the time diagram of the charging / discharging control operation | movement in the charging / discharging control apparatus of the lithium ion battery in Embodiment 1 of this invention. It is the schematic diagram which expanded the discharge period of the control operation time diagram shown in FIG. FIG. 7 is a signal processing flowchart executed by the first embodiment during the charge / discharge preparation period of the control operation time diagram shown in FIG. 6. FIG. 7 is a signal processing flowchart executed by the second embodiment during the charge / discharge preparation period of the control operation time diagram shown in FIG. 6. In the control by Embodiment 1 of this invention, it is a figure which shows the charging / discharging cycle characteristic when the discharge depth DoD in 10% of average electric charge residual quantity SoC conditions changes from 5%. In the control by Embodiment 1 of this invention, it is a figure which shows the charging / discharging cycle characteristic when the depth of discharge DoD on average charge residual quantity SoC50% conditions is 5%. In the control by Embodiment 1 of this invention, it is a figure which shows the charging / discharging cycle characteristic at the time of load sudden change (DoD10%-> 30%). It is a specific block diagram of the discharge current input part used for the charging / discharging control apparatus of the lithium ion battery in Embodiment 2 of this invention. A SoC-V _B characteristic diagram showing the relative potential of the control bias potential each quantity used for the charge and discharge control device of the lithium ion battery in the second embodiment of the present invention. In Embodiment 2 of this invention, it is a figure which shows the follow-up characteristic of the equilibrium potential Vm at the time of changing a discharge load amount in steps. It is a specific block diagram of the discharge current input part used for the charging / discharging control apparatus of the lithium ion battery in Embodiment 3 of this invention. In the third embodiment of the present invention, the depth of discharge DoD, average charge remaining SoD, it illustrates a table of _Q DOD -Vm conversion table showing the relationship between the equilibrium potential Vm. In Embodiment 3 of this invention, it is a figure which shows the relationship between the discharge depth DoD with respect to charge condition SoC _(min), and average charge residual amount SoC. In Embodiment 3 of this invention, it is a figure which shows the voltage dependence characteristic of a battery capacity | capacitance change rate. It is a figure which shows the charge control output characteristic of the first time by the charging / discharging control apparatus of the lithium ion battery in Embodiment 4 of this invention. It is a diagram illustrating a _{SoC-V B} characteristic of the general. It is a figure which shows the example of the discharge electric potential with respect to the external load change by the conventional charging / discharging control method, and remaining charge characteristics. A SoC-V _B characteristic diagram showing the relative potential of the control bias potential each quantity used in the conventional charge and discharge control method. It is a figure which shows the example of the voltage dependence characteristic of the battery capacity change rate by the conventional charge / discharge control method.

Embodiment 1 FIG.
Hereinafter, a charge / discharge control apparatus and control method for a lithium ion battery according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 is a schematic diagram of a charge / discharge control device for a lithium ion battery (hereinafter referred to as LIB) according to the present invention, FIG. 2 is a functional block diagram of the charge / discharge control device for LIB, and FIG. 3 is a discharge in the charge / discharge control device for LIB. FIG. 5 is a specific configuration diagram of the charging current output unit in the LIB charge / discharge control device.

In FIG. 1, the LIB charge / discharge control apparatus 100 supplies a charging current from the external power supply 300 to the LIB 200 when the LIB 200 is charged, and outputs a discharging current from the LIB 200 to the external load 400 when discharging.
The LIB charge / discharge control device 100 includes a control unit 20 and a charge / discharge processing unit 30, such as a charge time signal TCsw, a discharge time signal TDsw, and a charge current signal SIc from the control unit 20 to the charge / discharge processing unit 30. control signal is input, battery voltage signal SV B for the control unit 20 from the discharge unit _30, control signals such as the discharge current signal SI _D is adapted to be input. These control signals will be described in detail with reference to FIG.

FIG. 2 is a functional block diagram for explaining in detail the inside of the LIB charge / discharge control apparatus 100 shown in FIG. 1. The control unit 20 is composed of three modules: a discharge current input unit 21, a charge current output unit 22, and a timer scheduler 23. Composed.
The discharge current input unit 21 is a discharge current signal SI _D that is a discharge current _ID output from the charge / discharge processing unit 30 (in the case where S is added to the head of the code, it may indicate the signal; the same applies hereinafter) and enter the cell potential signal SV _B is a cell potential _{V B} of LIB200, second accumulated discharge charge signal SQ2 and the load state judgment first accumulated discharge charge signal SQ1 is the discharge charge quantity Q1 to be discharged charge amount Q2 The signal Ssel is output. The first integrated discharge charge signal SQ1, the second integrated discharge charge signal SQ2, and the load state determination signal Ssel will be described in detail with reference to FIG.

The charging current output unit 22 inputs the first integrated discharge charge signal SQ1, the second integrated discharge charge signal SQ2, and the load state determination signal Ssel output from the discharge current input unit 21, and uses the charge current Ic of the next cycle. A certain charging current signal SIc is output. The charge current signal SIc is input to the charge / discharge processing unit 30. The internal configuration of the charging current output unit 22 will be described in detail with reference to FIG.
The timer scheduler 23 outputs a charge time signal TCsw, which is a time control signal, to the charge / discharge processing unit 30 during the charge period, and a discharge time signal TDsw, which is a time control signal, to the charge / discharge processing part 30 during the discharge period. Output. In addition, a time start signal Ttrg is output to the discharge current input unit 21 and the charge current output unit 22.

The charge / discharge processing unit 30 includes a charge switch (SW1) 31, a charge current regulator (A1) 32, a discharge switch (SW2) 33, and a discharge current meter (A2) 34.
The charging switch (SW1) 31 is closed by the charging time signal TCsw transmitted from the timer scheduler 23, and a charging path for receiving a current supply from the external power source 300 is formed in the LIB 200, and the charging sequence is operated under the instruction of the timer scheduler 23. To do. At this time, the current regulator (A1) 32 receives the charging current signal SIc output from the charging current output unit 22, and performs current supply control in which the charging current Icrg is a constant value. During this charging, the discharge switch (SW2) 33 remains switched off.

On the other hand, the discharge switch (SW2) 33 is closed by the discharge time signal TDsw transmitted from the timer scheduler 23, a discharge path for supplying current from the LIB 200 to the external load 400 is formed, and the discharge sequence is performed under the instruction of the timer scheduler 23. Operate. At this time, the discharge current meter (A2) 34 is the discharge current _{I D} is measured and entered as a discharge current signal SI _D to the discharge current input 21. During this discharge, the charge switch (SW1) 31 remains switched off.

FIG. 3 is a detailed view of the inside of the discharge current input unit 21 shown in FIG. 2, and includes a discharge potential discrimination unit 21A, a discharge state determination unit 21B, and an equilibrium potential generation unit 21D.
The discharge potential discriminating unit 21A includes a comparator 211, a first integrator 212a, and a second integrator 212b. The battery potential signal SV _B , which is the battery potential V _B when the LIB 200 is discharged, and a discharge current meter (A2) 34 There are entering equilibrium potential signal SVm is a predetermined equilibrium potential Vm of the discharge current signal SI _D and equilibrium potential generating portion 21D has output a measured discharge current I _D.
The equilibrium potential generator 21D has a power source 218 that outputs a predetermined equilibrium potential Vm, and the equilibrium potential signal SVm of the equilibrium potential Vm is output to the discharge potential discrimination unit 21A and the discharge state determination unit 21B. Here, the predetermined equilibrium potential Vm is an intermediate potential in the charge / discharge cycle, and in the case of a steady load, the equilibrium is centered around this intermediate potential and is called an equilibrium potential. For example, regarding the cycle average charge amount, the potential value of the average charge amount obtained from the Qsoc-V _B curve measured at the initial stage or during the charge / discharge period is used.

Comparator 211 of the discharging potential discriminator 21A is balanced continuously cell potential signal SV _B compared process at the time of discharge potential signal SVm and LIB200, segmenting time discharge late discharge year discharge period LIB200. If it is determined that the discharge period is the first period, the discharge first period signal TRG1 is output, and if it is determined that the discharge period is the second period, the discharge late signal TRG2 is output.
Discharge year signal comparator 211 generates TRG1 and discharge late signal TRG2 outputs receives the time start signal Ttrg synchronized with the discharge time signal TDsw from the scheduler 23, the discharge late signal TRG2, the battery potential signal SV _B is predetermined Is output when it matches the balanced potential signal SVm (V _B = Vm).
Discharge of determining whether the previous year or late, the polarity of the difference between the potential _{V B} of the potential Vm and the battery voltage signal SV _B of equilibrium potential signal _{SVm (V B -Vm = ΔV B} m), the potential difference [Delta] V _B m is a positive In the case (V _B > Vm), the discharge previous period signal TRG1 is turned on and it is determined that the previous period. On the other hand, when the potential difference ΔV _B m is negative (V _B <Vm), it is determined that the late discharge signal TRG2 is turned on and the latter period.

  The first integrator 212a receives the previous discharge signal TRG1, starts integrating the discharge current signal SId, and the integration operation continues until the previous discharge signal TRG1 is turned off. During this time, the first integrator 212a outputs a first integrated discharge charge signal SQ1 obtained by current integration in the first (previous term) integration period. Similarly, the second integrator 212b receives the late discharge signal TRG2, starts integrating the discharge current signal SId, and continues the integration operation until the late discharge signal TRG2 is turned off. During this time, the second integrator 212b outputs a second integrated discharge charge signal SQ2 obtained by current integration in the second (late) integration period.

Discharge state determination unit 21B, the signal holder 213a is a three temporary storage means, 213b, is composed of 213c and one discharge state judging unit 217, the load and enter the equilibrium potential signal SVm the cell potential signal SV _B of LIB200 The quantity determination signal Ssel is output.
Of the three signals holders, signal holder 213a is charged to temporarily store the charge last train position signal SVec as charged last train position Vec discharge initial enter the cell potential signal SV _B of the discharge period to discharge immediately before the start of LIB200 a last train position holder, likewise the signal holder 213b is discharged last train position holder for temporarily storing discharge last train position signal SVed as a discharge last train position Ved at the end of discharge of the discharge end immediately to enter the cell potential signal SV _B LIB200 It is. The signal holder 213c is an equilibrium potential holder that temporarily stores an equilibrium potential signal SVm that is a predetermined equilibrium potential Vm output from the equilibrium potential generator 21D. The storage by the three signal holders 213a, 213b and 213c is temporarily stored according to the time start signal Ttrg from the timer scheduler 23, respectively.

The discharge state determiner 217 inputs the charge end potential signal SVec, the discharge end potential signal SVed, and the equilibrium potential signal SVm, which are outputs from the three signal holders 213a, 213b, and 213c, and is based on the following conditional expression (1): Thus, it is determined whether the load state during discharge is (a) steady load, (b) light load, or (c) heavy load, and a load amount determination signal Ssel is output as a determination result. This process is performed when three signals are ready in the preparation period after the end of discharge.
(A) Steady load: Ved <Vm, Vec> Vm
(B) Light load: Ved> Vm, Vec> Vm (1)
(C) Heavy load: Ved <Vm, Vec <Vm

Figure 4 is manifested in either a straight line plotted on Q _SOC -V _B curve so that the relative position is known for the control potential level (equilibrium potential Vm, the charging last train position Vec, and discharging the last train position Ved) in three discharge load state FIG. In FIG. 4A, since the charge end potential Vec is larger than the equilibrium potential Vm and the discharge end potential Ved is smaller than the equilibrium potential SVm, (a) it is determined as a steady load. In FIG. 4B, since the charge end potential Vec is greater than the equilibrium potential Vm and the discharge end potential Ved is greater than the equilibrium potential SVm, it is determined that (b) light load. In FIG. 4C, the charge end potential Vec is smaller than the equilibrium potential Vm, and the discharge end potential Ved is smaller than the equilibrium potential SVm.
In this way, the discharge state determination unit 217 determines the load amount determination signal Ssel that has determined the state of the discharge load state into three patterns of a steady load, a light load, and a heavy load by a comparison process between the battery potential signal SV _B and the equilibrium potential signal SVm. Output.

FIG. 5 is an internal detailed diagram of the charging current output unit 22 shown in FIG. 2. The steady load amount calculation unit 221 A, the light load amount calculation unit 221 B, the heavy load amount calculation unit 221 C, the selector 223, and the charging current output calculation unit 224 It is configured. The selector 223 selects the steady load amount calculator 221A, the light load amount calculator 221B, and the heavy load amount according to the discharge state (steady load, light load, heavy load) of the load amount determination signal Ssel from the discharge state determiner 217. One of the parts 221C is selected.
The charging current output unit 22 receives the first integrated discharge charge signal SQ1, the second integrated discharge charge signal SQ2, and the load amount determination signal Ssel from the discharge current input unit 21, and outputs the charge current signal SIc at the next cycle. Output.

The load amount calculation units 221A, 221B, and 221C of the charging current output unit 22 include the first accumulated discharge charge amount Q1 (i) and the first accumulated discharge charge among the i-th discharge cycles output from the discharge potential discriminating unit 21A. From the accumulated discharge charge amount Q2 (i) of 2, the next step cycle number (i + 1) times according to the discharge state (steady load, light load, heavy load) of the load amount determination signal Ssel output from the discharge state determiner 217. A charge amount Qc (i + 1) necessary for the calculation is calculated according to the equation (2).
Qc (i + 1) = K1 * Q1 (i) + K2 * Q2 (i) (2)
Here, K1 and K2 are coefficient values according to the load state (steady load, light load, heavy load) by the load amount determination signal Ssel, and K1 and K2 select different values according to the load state.
Then, the charging current output calculation unit 224 determines the charging current signal SIc at the next cycle from the charging charge signal SQc that is the charging charge amount Qc and a predetermined charging time Tw.

Next, the operation of the lithium ion battery charge / discharge control apparatus described in FIGS. 1 to 3 and FIG. 5 will be described with reference to FIGS.
6 is a time diagram (schematic diagram) of the charge / discharge control operation of the LIB charge / discharge control device 100, and FIG. 7 is a time diagram of the control operation during the discharge period of the LIB charge / discharge control device 100.
In general, the LIB 200 is connected to the external power source 300 and the external load 400, and the capacity is irreversibly decreased in proportion to the number of repeated charge / discharge cycles and even when there is no load in the charged state. Thus, the charge capacity Ccell that can be stored in the LIB 200 is reliably reduced depending on the number n of charge / discharge cycles and the charge storage amount Q immediately after manufacture.

The present invention provides a charge / discharge cycle control technique and means for avoiding the overcharge and overdischarge risks of the LIB 200 and achieving the battery's original optimum cycle life.
In addition, when the average charge remaining in the charge / discharge cycle is high, battery deterioration due to cycle performance and power storage is considered to proceed at the same time, so the stress on the battery under load fluctuations should be minimized. By performing charge / discharge control, the excess capacity is reduced and a light weight effect is also expected.

As shown in the time diagram of FIG. 6, the charge / discharge control operation of the LIB charge / discharge control apparatus 100 includes three steps of a charge period excluding standby, a discharge period, and a charge / discharge preparation period.
In the charging period of the first step, the timer scheduler 23 of the control unit 20 sends a charging signal based on the charging time signal TCsw, turns on the charging switch (SW1) 31 of the charging / discharging processing unit 30, and the LIB 200 from the external power source 300. Start charging. At this time, the current regulator (A1) 32 receives the charging current signal SIc output from the charging current output unit 22 of the control unit 20, and performs current supply control with the charging current Icrg shown in FIG. The battery is charged while the current supplied to the LIB 200 is controlled, and the battery potential V _B also rises.
After a predetermined time elapses or when the charging condition is satisfied, the charging time signal Tcsw turns off the charging switch (SW1) 31 and ends the charging.

In the discharge period, which is the second process after the subsequent standby period, the timer scheduler 23 outputs the discharge time signal TDsw, turns on the discharge switch (SW2) 33 of the charge / discharge processing unit 30, and discharges from the LIB 200 to the external load 400. Output current. The discharge operation is terminated when the discharge time signal TDsw output from the timer scheduler 23 changes to “low”. During the discharge period, the discharge current meter (A2) 34 to discharge current _{I D} from the load current _{I L} samples measured to determine the discharge charge quantity _{Q D} from the discharge current signal SI _D. The discharge period is divided into two periods, a first integration period that is the first period and a second integration period that is the second period, and the discharge charge amount is calculated.

Here, in the discharge phase time diagrams relating to the charge and discharge control operation of FIG. 6, the equilibrium potential Vm of a predetermined equilibrium potential signal SVm output by the cell potential V _B and the equilibrium potential generating portion 21D of the cell potential signal SV _B In the potential comparison, if V _B > Vm, the discharge first period signal TRG1 is turned on, and the first integrator 212a outputs the first integrated discharge charge signal SQ1 obtained by current integration in the first (previous period) integration period.
Further, in the potential comparison between the battery potential V _B and the equilibrium potential Vm, if V _B <Vm, the discharge late signal TRG2 is turned on, and the second integrator 212b performs current integration in the second (late) integration period. Output the accumulated discharge charge signal SQ2. Then, using this first integrated discharge charge signal SQ1 and second integrated discharge charge signal SQ2, the unbalanced component is extracted as an adjustment amount.
The state of this integration operation is schematically shown by a ramp function that linearly rises in the first integrated discharge charge signal SQ1 and the second integrated discharge charge signal SQ2 in FIG.

Further explanation will be given based on FIG. 7 in which the discharge signal waveform in the discharge period of FIG. 6 is enlarged. The battery potential V _B of the LIB potential signal SV _{B that} decreases with time in the discharge period is continuously acquired and the discharge time is started. The first integration period, which is the first period of the discharge period, is divided into two sections, a first integration period from the time T1 to the equilibrium potential arrival time Tk and a second integration period from the equilibrium potential arrival time Tk to the discharge end time T2. The acquired first integrated discharge charge signal SQ1 and the second integrated discharge charge signal SQ2 acquired in the second integration period which is the latter period are obtained.
Next, in the charge / discharge preparation period of the third process following the charge period of the first process and the discharge period of the second process, the LIB control circuit 100 performs pre-processing for entering the charge operation of the next step according to the scheduler 23. Do. This processing flow will be described with reference to FIG.

In FIG. 8A, processing proceeds in parallel with two steps described below. One is the calculation of the charge amount Qc for the next step charging process, and the other is the setting of the equilibrium potential Vm. This equilibrium potential Vm in the discharge period is a discrimination level that is set to separate and measure the first (first half) accumulated discharge charge amount Q1 and the second (late) accumulated discharge charge amount Q2 corresponding to the charge amount Qc. In the steady state, the charge amount Qc is calculated and controlled so that the first accumulated discharge charge amount Q1 and the second accumulated discharge charge amount Q2 coincide with each other with the equilibrium potential Vm as the center.
In the calculation process of the charge amount Qc, the charge amount depends on three types of discharge load modes: (a) steady load, (b) light load, and (c) heavy load.

The discharge load state determination process is performed by the discharge state determination unit 21B. In the processing flow on the left side of FIG. 8A, the discharge state determination unit 217 of the discharge state determination unit 21B is based on the time start signal Ttrg from the timer scheduler 23, and is the final charge that is output from the three signal holders 213a, 213b, and 213c. From the potential Vec, the final discharge potential Ved, and the equilibrium potential Vm, the load amount determination signal Ssel is output according to the equation (1).
Then, the values of the coefficients K1 and K2 in the equation (2) are changed according to the load state.
The coefficients K1 and K2 employ the following values as an example.
(A) Steady load K1 = 0.75, K2 = 1.25
(B) Light load K1 = 0.5, K2 = 0.5
(C) Heavy load K1 = 1.0, K2 = 1.0
The calculation according to the equation (2) is performed by selecting any one of the steady load amount calculation unit 221A, the light load amount calculation unit 221B, and the heavy load amount calculation unit 221C in FIG.
By considering the weighting factors K1 and K2 in this way, the charging amount is increased according to the weighting factor 1 particularly in heavy loads, and the charging replenishment amount is reduced by 50% at light loads, so that it gradually converges to the equilibrium potential Vm. It is effective in that the charge charge amount can be controlled more stably.

The right-side process flow in FIG. 8A is to obtain an equilibrium potential Vm that is a set potential for dividing the discharge period into the first and second periods, and the initially expected cycle average charge amount Qm is Qsoc− measured during the initial period or during the period. Obtained from V _B curve. The equilibrium potential Vm is uniquely determined from the cycle average charge amount Qm, and is output from the power source 218 of the equilibrium potential generator 21D. In the case of a steady load, the equilibrium is centered around this equilibrium potential Vm, and therefore called the equilibrium potential Vm.

FIGS. 9 to 11 relate to the battery voltage V _B and the residual charge Qsoc during charge / discharge cycle control when the average charge remaining amount Qsoc equivalent to 50% is set to the equilibrium potential Vm in the case where charge / discharge control is performed according to the present invention. FIG. 9 is a diagram showing a time lapse characteristic. FIG. 9 is a response characteristic diagram when the discharge depth DoD is changed from 10% to 5%. FIG. 10 is a response characteristic diagram when the discharge depth DoD is changed within 5%. FIG. 11 is a response characteristic diagram when the load suddenly changes (when the discharge depth DoD changes from 10% to 30%).
Thus, as long as the set potential (equilibrium potential Vm) corresponding to the cycle average charge amount Qm is kept constant, the charge / discharge average charge amount under the charge / discharge cycle is stabilized.

  In the first embodiment, the time average value of the remaining amount of charge in the charge / discharge cycle is set as the equilibrium potential Vm, and the set voltage value is set. From the two measured amounts and the load state, the first (first period) accumulated discharge charge amount Q1 up to the set set voltage and the second (late stage) accumulated discharge charge amount Q2 from the subsequent set voltage to the discharge end voltage (formula ( Charge using the charge amount Qc to be replenished in 2).

  As described above, the first embodiment of the present invention calculates the equilibrium potential Vm, which is the set potential, by always obtaining the average potential as the middle potential so that the charge amount control by the cycle average charge amount Qm can be performed. The discharge period is divided into the first and second periods as a reference, and the first and second discharge charges Q1 and Q2 are calculated, respectively. On the other hand, changing the weighting coefficient according to the load conditions during discharge (steady load, light load, heavy load) and calculating the charge amount at the time of charging in the next cycle enables stable charge amount replenishment, This has the effect of avoiding overcharge and overdischarge risks.

Embodiment 2. FIG.
Next, a charge / discharge control apparatus and control method for a lithium ion battery according to Embodiment 2 of the present invention will be described with reference to FIGS. 12 to 14 and FIG. 8B.
FIG. 12 is a specific configuration diagram of the discharge current input unit 21 used in the control unit of the LIB charge / discharge control apparatus according to the second embodiment. Other configurations are the same as those in the first embodiment, and a configuration diagram and description thereof are omitted.
In FIG. 12, the discharge current input unit 21 includes a discharge potential discrimination unit 21A, a discharge state determination unit 21B, and an equilibrium potential generation unit 21C. Here, the discharge potential discrimination unit 21A and the discharge state determination unit 21B are the same as those in FIG. 3 of the first embodiment, but in the second embodiment, an equilibrium potential generation unit is used instead of the equilibrium potential generation unit 21D of the first embodiment. 21C is provided. The equilibrium potential generation unit 21 </ b> C includes a charge amount adder 214 and a discharge depth-equilibrium potential converter (DoD-Vm converter) 215.

As in the case of the first embodiment, the discharge potential discriminating unit 21A is the same as the first embodiment in the comparison process between the battery potential SV _B that is decreasing during discharge and the equilibrium potential Vm for discrimination. The first cumulative discharge charge amount Q1 and the second cumulative discharge charge amount Q2 in the late stage of discharge are discriminated by dividing the discharge time into two. Further, the discharge state determination unit 21B determines that the load state at the time of discharge is (a) based on the comparison between the charge end potential signal SVec, which is the battery potential V _B , the discharge end potential signal SVed, and the equilibrium potential Vm for discrimination. It is determined whether the load is a steady load, (b) a light load, or (c) a heavy load.
The charge amount adder 214 of the equilibrium potential generating unit 21C receives the first integrated discharge charge signal SQ1 and the second integrated discharge charge signal SQ2 that are the outputs of the discharge potential discriminating unit 21A, and simply adds them to calculate the discharge depth. A discharge charge signal SQ _DOD corresponding to DoD is output. The DoD-Vm converter 215 receives the discharge charge signal SQ _DOD and calculates the equilibrium potential Vm. This calculation will be described in detail below.

Since the discharge depth DoD of the charge / discharge cycle varies with the load variation, the cycle average charge amount Qm also varies accordingly. Therefore, it is necessary to perform tracking control so that the equilibrium potential Vm is set accordingly in the next cycle. There is.
In the second embodiment, in the two physical quantities of the discharge depth DoD (discharge depth amount) and the cycle average charge amount Qm obtained during the cycle discharge, the discharge depth 50% during the discharge is the cycle average charge amount during the next cycle. Thus, a method and means for charge replenishment are provided.
In such a cycle charge / discharge, the means for controlling the charge amount so that the time average value of the remaining charge of the LIB 200 becomes 50% of the discharge depth DoD at the time of the discharge cycle, so that the battery deterioration under the charge / discharge cycle can be suppressed. , The average value of the remaining charge of the LIB 200 is set and controlled.
An algorithm relating to charge amount control in the second embodiment will be described below.
The capacity decrease that progresses during the charge / discharge cycle is related to the total charge amount (Q _cell × F _100% ) determined from the repeated cycle and the charge amount. In the simplified model equation (3) relating to capacity deterioration, the first term in the equation is a deterioration factor that depends on the number of cycles, and the second term is a deterioration factor that depends on the amount of stored charge.

Qcell × F _100%
∝α1 × n × Qcell × DoD + α2 × Qm × Tlimit
∝α1 × Tlimit / Td × Qcell × DoD + α2 × Qm × Tlimit (3)
n: number of cycles Qcell: battery capacity [AH]
F _100% : Charging / discharging cycle life (DoD _100% ) [times]
Tlimit: Limit cycle number [Hrs]
Td: charge / discharge cycle [Hrs]
DoD: depth of discharge [%] Qm: remaining average charge [AH]
α1: Cycle limit coefficient α2: Storage life coefficient The limit cycle number Tlimit in equation (3) is an effect coefficient FOM that contributes to the service life of the battery.
Substituting (Figure-Of-Merit), the following expression (4) is derived.

Equation (4) indicates that the degradation life of LIB 200 depends on the battery capacity Qcell, the charge / discharge cycle Td, and the cycle average charge amount Qm.
When charging the same amount as the discharge amount, the control means according to the second embodiment takes into _account the restrictions on the upper limit value (Q _{SOC_max} ) and the lower limit value (Q _{SOC_min} ) of the storage capacity, and the cycle average charge amount Qm is Charge control is performed so that the same amount as Q _DOD / 2.
Figure 13 is a _{SoC-V B} characteristic diagram showing the relative potential of the control bias potential each amount, the upper limit of the storage capacity _{(Q SOC_max)} corresponds to the upper limit value VUL of Figure 13, the lower limit value _{(Q SOC_min)} is This corresponds to the lower limit value VLL in FIG.

Here, the DoD-Vm converter 215 of the equilibrium potential generation unit 21C in the second embodiment calculates the relationship between the discharge depth Q _DOD and the average charge amount Qm.
Qm = Q _DOD / 2 + Q _{SOC_min} (5)
To maintain.
Thus, the cycle average charge amount Qm to be controlled obtained from the discharge depth Q _DOD can uniquely determine the equilibrium potential Vm, and outputs the equilibrium potential Vm.
The right-side process flow in FIG. 8B is to obtain an equilibrium potential Vm that is a set potential for dividing the discharge period into the first and second periods. The first discharge charge amount Q1 from the start of the discharge voltage to the preset equilibrium potential Vm Then, the two measured amounts of the second discharge charge amount Q2 from the subsequent equilibrium potential Vm to the discharge end voltage are added, and the cycle average charge amount Qm in the next cycle period is added from the added discharge charge amount Q _{DOD according} to the equation (5). And the equilibrium potential Vm is calculated from the cycle average charge amount Qm.
That is, the equilibrium potential generating unit 21C repeats both charging and discharging operations at a steady load within the range of the remaining charge upper limit and lower limit, and the battery potential V _B and the remaining battery charge Q _SOC according to the discharge depth DoD. In the charging / discharging cycle process in which time fluctuates, the equilibrium potential Vm is determined from the sum of the discharge depth 50% (Q _DOD / 2) measured during the charge / discharge cycle discharge period and the remaining charge lower limit amount Q _{SOC_min} .
By substituting equation (5) into equation (4), the FOM value becomes the following equation (6).

Equations (5) and (6) are advantageous in improving the limit cycle number Tlimit if the average charge amount Qm is set as low as possible in accordance with the discharge depth Q _DOD that varies depending on the load state of each cycle. Indicates.
Therefore, in the case of a light load, the LIB charge / discharge control apparatus 100 sets the equilibrium potential Vm as low as possible with reference to the Qsoc-V _B curve so that the cycle average charge amount Qm value is kept low.
FIG. 14 is an example schematically showing a shift to the optimal equilibrium potential Vm (corresponding to the equilibrium charge amount Qm) corresponding to the discharge depth DoD depending on the external load amount.
Here, as Qsoc-V _B curve reference means about cycle average charge amount Qm and discharge depth DoD in charge and discharge cycles may be used discrete numerical sequences using a table.

As described above, in the invention of the second embodiment, both charging and discharging operations at a steady load are repeated within the range of the remaining charge upper limit and lower limit, and the battery potential V _B and the remaining battery charge are determined according to the discharge depth DoD. In the charge / discharge cycle process in which the amount varies with time, the LIB charge / discharge control device uses the cycle average charge amount Qm as the control amount, and the equilibrium potential Vm is the sum of the discharge depth amount 50% and the remaining charge lower limit amount. Since it is determined, the charge amount in the next cycle charging period is appropriately performed.
As described above, the cycle average charge amount during the charge / discharge cycle is controlled by following the change in the discharge load amount, so that the excessive amount of the charged amount can be thoroughly eliminated and the storage deterioration due to the high charge can be alleviated. There is an effect that the battery stress is greatly relieved by reducing the capacity deterioration caused by the accumulated charge amount in the discharge cycle.

Embodiment 3 FIG.
Next, a charge / discharge control apparatus and control method for a lithium ion battery according to Embodiment 3 of the present invention will be described with reference to FIGS.
FIG. 15 is a specific configuration diagram of the discharge current input unit 21 used in the control unit of the LIB charge / discharge control apparatus according to the third embodiment. Other configurations are the same as those in the first embodiment, and a configuration diagram and description thereof are omitted.
In FIG. 15, the discharge current input unit 21 includes a discharge potential discrimination unit 21A, a discharge state determination unit 21B, and an equilibrium potential generation unit 21C. Here, the discharge potential discriminating unit 21A and the discharge state determining unit 21B are the same as those in FIG. 3 of the first embodiment, but in the third embodiment, an equilibrium potential generating unit is used instead of the equilibrium potential generating unit 21D of the first embodiment. 21C is provided. The equilibrium potential generation unit 21C includes a charge amount adder 214, a discharge depth-equilibrium potential converter (DoD-Vm converter) 215, and a conversion coefficient reference unit 216.

The conversion coefficient reference unit 216 refers to a Q _DOD- Vm conversion table written in advance for the cycle average charge amount Qm obtained from the discharge current amount Id, and stores a numerical value for conversion to the equilibrium potential Vm used for the discrimination level. ing. For the specific conversion table, a temporary storage element such as a flash memory is used.
If the discharge load amount is a constant steady state, the elapsed time characteristic of the charge remaining amount Q _SOC of the LIB 200 that repeats charging and discharging is stabilized centering on the cycle average charge amount Qm. Stable state of the charging and discharging, the discharge current I _D and can be confirmed from the battery voltage V _B. Here, the equilibrium potential Vm can be obtained from the cycle average charge amount Qm with reference to the Q _SOC -V _B curve of FIG.
In general, the function of the remaining charge amount Q _SOC in the Q _SOC -V _B curve with respect to the potential V _B is expressed by a high-order function as represented in FIG. In this proposal, a table reference method based on rough function approximation is used for the conversion process.

In the invention of the third embodiment, when converting to the equilibrium potential Vm by using the obtained discharge quantity Q _DOD during discharge, so far in place of the charge remaining SoC- battery voltage V _B transformation function expression shown in FIG. 16 Refer to the conversion table of the Q _DOD -Vm numerical table listed in the table. The table in FIG. 16 approximates the potential range with six points, but the influence on the control due to the characteristic deterioration is slight.
As an example, for example, when the discharge charge amount is Q _DOD 10%, the equilibrium potential Vm is output as 3.721 V with reference to the table of FIG. Here, in the case of a Q _DOD value between 10% and 20%, it is determined by linear interpolation, or a 20% value can be adopted when rough approximation is sufficient.
FIG. 17 shows the relationship between the discharge depth DoD and the cycle average charge amount Qm with respect to SoC _(min) . FIG. 17 shows that the relationship between both variables varies depending on the SoC (min) value of 0% to 20%.

The charge amount adder 214 in FIG. 15 receives the first accumulated discharge charge signal SQ1 and the second accumulated discharge charge signal SQ2 that are the outputs of the discharge potential discriminating unit 21A, and simply adds them to the discharge depth DoD. The corresponding discharge charge signal SQ _DOD is output. The DoD-Vm converter 215 receives the discharge charge signal SQ _DOD , refers to the numerical signal from the conversion coefficient reference unit 216, and outputs a balanced potential signal SVm. As an example, the conversion coefficient reference unit 216 uses a table in which six sets of numerical array data shown in the table of FIG. 16 are stored.
In the table of FIG. 16, the discharge depth Q _DOD is managed as a range of discharge amount from 10% to 100%. Here, the average charge remaining amount Qm corresponding to each discharge depth Q _DOD is lower than the upper limit amount so that Qm is 10% when Q _{DOD is} 10% and Qm is 55% when Q _{DOD is} 100%. Charge / discharge control is performed with a limited amount determined.
Further, it is obvious that the equilibrium potential Vm corresponding to the average charge remaining amount Qm is uniquely determined. In the case of a steady load, the equilibrium is centered around this equilibrium potential Vm, and therefore called the equilibrium potential Vm.

  As described above, in the third embodiment, the equilibrium potential Vm, which is the discrimination potential set by the control unit 20 during the charge / discharge cycle operation, is determined from the discharge depth DoD for each cycle. The cycle average charge amount Qm in the next cycle period is calculated using the depth amount of the discharge load measured in the following, and the equilibrium potential uniquely determined from the battery potential characteristic with respect to the remaining charge amount of the LIB 200 from the average charge amount Qm. In the conversion process of Vm, the equilibrium potential Vm is generated using a reference table that is converted by referring to the discrete value table of the LIB initial characteristic Qm-Vm.

In the third embodiment, since the equilibrium potential generation unit 21C determines the equilibrium potential Vm depending on the discharge depth Q _DOD in the discharge period, when the cycle average charge amount Qm varies, the discharge depth Q _DOD is constant. In order to maintain the relationship, the equilibrium potential Vm is made to follow.
The tracking characteristic of the cycle average charge amount Qm is the same as that of FIG. 14 described in the second embodiment. FIG. 14 shows how the load changes stepwise within the range of steady loads. From FIG. 14, the discharge depth DoD value and the cycle average charge amount Qm value are in a proportional relationship. Since the equilibrium potential Vm uniquely corresponds to the average charge remaining amount Qm, it changes stepwise according to the load amount.

Briefly explaining the operation of the third embodiment, if the discharge depth DoD is small, the average remaining charge Qm is also set to a low state according to the present algorithm under the charge / discharge cycle. On the contrary, if the value becomes larger, the average charge remaining amount Qm value is increased up to the maximum SoC 55%.
Actually, it may not always be preferable to follow the equilibrium potential Vm value at every cycle in response to random load fluctuations. For this reason, it is possible to delay the response follow-up time with respect to the change in the discharge depth DoD by inserting a low-frequency filter.
FIG. 18 shows a charge / discharge cycle diagram for two cycles in which the time of a steady load is expanded. In FIG. 18, since the charge end potential Vec and the discharge end potential Ved are the same value in both cycles, the follow-up control operation of the equilibrium potential Vm is not performed.

As described above, the invention of Embodiment 3 uses the discharge depth measured in the charge / discharge cycle discharge period in order to change the cycle charge / discharge equilibrium potential Vm in accordance with the discharge load amount (DoD value). The average charge amount in the cycle period is calculated, and from the average charge amount, the equilibrium potential is determined by the discharge depth-equilibrium potential table by a discrete numerical sequence that uniquely determines the equilibrium potential from the battery potential characteristics with respect to the remaining charge amount of LIB. Since it is generated, it can be used even if the battery potential changes with respect to the remaining charge during the battery deterioration process, and there is an effect of avoiding overcharge and overdischarge risks.
In addition, since the cycle average charge amount during the charge / discharge cycle is controlled in accordance with the fluctuation of the discharge load amount, the period of the high charge state is reduced, and the capacity deterioration due to the accumulated charge amount of the charge / discharge cycle is reduced. It has the effect of significantly reducing battery stress.

Embodiment 4 FIG.
Next, a charge / discharge control apparatus and control method for a lithium ion battery according to Embodiment 4 of the present invention will be described with reference to FIG.
In the invention of the fourth embodiment, when the external load 400 is unknown or when charging from the storage state, the LIB 200 is controlled to be charged to high charge or full charge only for the first time.
That is, when the LIB 200 is in the storage mode or in a low power standby state, the LIB 200 is set to a fully charged state or a high charged state before the start of discharging only for the first discharge when the LIB 200 is connected to the external load 400. is there.

FIGS. 19A and 19B are diagrams showing the charge control output characteristics when high charge is performed only in the first charge operation according to the fourth embodiment. FIG. 19A is a charge / discharge voltage, and FIG. 19B is a SoC time characteristic. It is. As shown in FIG. 19, the LIB 200 has a characteristic that the battery voltage V _B is stably attenuated until it reaches the equilibrium potential (SoC 50%) after being fully charged up to 4.1 V in 200 sec after the start by the first charging operation. Indicates.
As described above, in the fourth embodiment, when the external load 400 is unknown and when charging from the stored state of the LIB 200, it is limited to one time at the time of transition from the standby or stored state to the steady load state. The LIB control device 100 controls charging of the LIB 200 to full charge or high charge.

When the external load 400 is expected to transition from the low load state to the high load state, the LIB controller 100 is limited to the LIB 200 only when the LIB 200 is fully charged or the high charge operation is transitioned from each mode to the high load state. Charge control of full charge or high charge.
In steady operation, the control method of the present invention can provide a stable and dynamic transition response as described above. For example, when the external load 400 at the initial startup is unknown or when the external load 400 is started up from the storage In the case of, it is effective in avoiding an overdischarge trouble by making the high charge once only at the first charge.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made. Within the scope of the present invention, each embodiment is described. These embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

20: Control unit, 21: Discharge current input unit, 21A: Discharge potential discrimination unit,
21B: discharge state determination unit, 21C: equilibrium potential generation unit, 21D: equilibrium potential generation unit, 22: charging current output unit, 23: timer scheduler, 30: charge / discharge processing unit,
31: Charge switch (SW1), 32: Charge current regulator (A1),
33: Discharge switch (SW2), 34: Discharge current meter (A2),
100: LIB charge / discharge control device, 200: lithium ion battery (LIB),
300: External power supply, 400: External load, Q1: First (first half) integrated discharge charge amount Q2: Second (second half) integral discharge charge amount, Ssel: Load amount (discharge state) determination signal,
Vm: equilibrium potential, Vec: final charge potential, Ved: final discharge potential

Claims (8)

A control unit including a discharge current input unit, a charging current output unit, a timer scheduler, a charging circuit that receives a supply current from an external power source and charges the lithium ion battery by a control signal from the control unit, and the lithium ion battery. A charge / discharge processing unit that forms a discharge circuit that outputs a discharge current of
The discharge current input unit includes a first discharge charge amount Q1 measured in the previous period based on a predetermined equilibrium potential for discriminating the discharge period of the lithium ion battery into two sections, and a second discharge charge measured in the latter period. A discharge potential discriminating unit for calculating the amount Q2, and a discharge state determining unit for determining a load state at the time of discharge, wherein the charge current output unit is configured to output the first discharge charge amount Q1 from the discharge current input unit; A charge / discharge control device for a lithium ion battery, wherein the charge charge amount Q of the next cycle is calculated from the second discharge charge amount Q2 and the load state from the discharge state determination unit according to the following equation.
Q = K1 × Q1 + K2 × Q2
However, the coefficients K1 and K2 are different values depending on the load state. The discharge current input unit includes an equilibrium potential generation unit for generating a predetermined equilibrium potential for discriminating the discharge period of the lithium ion battery into two sections, and the equilibrium potential from the equilibrium potential generation unit is: The charge / discharge control of the lithium ion battery according to claim 1, wherein the charge potential is an intermediate potential of the lithium ion battery at the initial stage of the charge / discharge cycle or an average charge amount obtained from a Qsoc-V _B curve measured during the charge / discharge cycle. apparatus.   The discharge current input unit includes an equilibrium potential generation unit for generating a predetermined equilibrium potential for discriminating a discharge period of the lithium ion battery into two sections, and the equilibrium potential generation unit is a steady load. In the charge / discharge cycle process in which both the charging and discharging operations are repeated within the range of the remaining charge upper limit and lower limit, and the battery potential and the remaining charge amount of the battery vary with time, the equilibrium potential is The charge / discharge control device for a lithium ion battery according to claim 1, wherein the charge / discharge control device is determined from a sum of a discharge depth of 50% measured in a discharge cycle discharge period and the amount of the remaining charge lower limit.   The discharge current input unit includes an equilibrium potential generation unit for generating a predetermined equilibrium potential for discriminating a discharge period of the lithium ion battery into two sections, and the equilibrium potential generation unit is configured to perform charge / discharge cycle discharge. The average charge amount of the next cycle period is calculated using the discharge depth measured in the period, and the equilibrium potential is uniquely determined from the battery potential characteristic with respect to the remaining charge amount of the lithium ion battery from the average charge amount− 2. The charge / discharge control device for a lithium ion battery according to claim 1, further comprising an equilibrium potential table, wherein the equilibrium potential is generated based on the depth-of-discharge-equilibrium potential table. The discharge state determination unit determines a load state as a steady load, a light load, and a heavy load, and the coefficients K1 and K2 are set to the following values according to the load state. The charge / discharge control device for a lithium ion battery according to any one of 4.
(A) Steady load K1 = 0.75, K2 = 1.25
(B) Light load K1 = 0.5, K2 = 0.5
(C) Heavy load K1 = 1.0, K2 = 1.0   The lithium-ion battery charge / discharge control device makes the lithium-ion battery fully charged or charged only once at the time of transition when the lithium-ion battery transits from a standby or stored state to a steady load state. The charging / discharging control apparatus of the lithium ion battery of any one of Claim 1 to 5 which was made to do. When a transition from a low load state to a high load state is expected, the charge / discharge control device for the lithium ion battery is configured to fully charge or charge the lithium ion battery only once during the transition. The charge / discharge control apparatus for a lithium ion battery according to any one of claims 1 to 5. Switching control between a charging circuit that receives a supply current from an external power source and charges a lithium ion battery and a discharge circuit that outputs a discharge current from the lithium ion battery to an external load, and according to the discharge amount of the lithium ion battery In a charge / discharge control method for a lithium ion battery that is controlled to perform charging,
Distinguishing the discharge period of the lithium ion battery into two sections based on a predetermined equilibrium potential, calculating a first discharge charge amount Q1 measured in the previous period and a second discharge charge amount Q2 measured in the latter period, and discharging The load state at the time is discriminated, and the charge amount Q of the next cycle is calculated from the first discharge charge amount Q1, the second discharge charge amount Q2, and the load state at the time of discharge according to the following equation. A charge / discharge control method for a lithium ion battery.
Q = K1 × Q1 + K2 × Q2
However, the coefficients K1 and K2 are different values depending on the load state.