JP6696358B2 - Control device for hybrid vehicle - Google Patents

Description

  The present invention relates to a control device for a hybrid vehicle including an engine, a motor generator, and a battery.

  Hybrid vehicles driven by an engine and a motor generator are often used. In such a hybrid vehicle, engine start and stop are frequently repeated. When stopping the engine, a method is used in which the motor generator functions as a generator to reduce the engine speed. At this time, the electric power generated by the motor generator is charged in the battery (see, for example, Patent Document 1).

  On the other hand, a lithium ion secondary battery is being applied as a battery mounted on a hybrid vehicle. The lithium ion secondary battery has a high energy density and a high output voltage, and thus is suitable for a vehicle-mounted battery that requires a large battery capacity and a high voltage.

  However, the lithium ion secondary battery is used in a usage mode (for example, charging at a high rate, charging from a high charging state (high SOC), continuous charging for a long time, charging at a low temperature (charging in a high resistance state)), Lithium (Li) metal may be deposited on the negative electrode surface of the lithium ion secondary battery, and as a result, deterioration or performance deterioration of the lithium ion secondary battery may be caused. Therefore, control has been proposed in which the input permission power to the battery is adjusted based on the history of charging / discharging to suppress the deposition of lithium metal on the negative electrode of the lithium ion secondary battery (see, for example, Patent Document 2). Specifically, based on the current of the battery, the maximum current value at which lithium metal does not deposit is sequentially calculated, and the input allowable power to the battery is adjusted so that the battery current does not exceed the maximum current value.

  In this control, the charging power to the battery is limited at a high rate (rate of change over time), and accordingly, the regenerative braking force is also limited. Therefore, in a hybrid vehicle equipped with a lithium-ion secondary battery, control for limiting the charging current is performed so as to suppress deposition of lithium metal, and then brake cooperative control between hydraulic braking and regenerative braking is achieved. It has been proposed (see, for example, Patent Document 3).

JP, 2014-113869, A International Publication No. 2010/005079 Pamphlet JP, 2012-223044, A

  By the way, in a lithium ion secondary battery, the lower the temperature, the more easily lithium (Li) metal is deposited on the surface of the negative electrode. Therefore, if regenerative braking is continued for a long time at an extremely low temperature, the input allowable power to the battery is greatly limited. Therefore, when the engine is stopped, the battery cannot be charged with the electric power generated by the motor generator, and the motor generator may not function as a generator to reduce the engine speed. In this case, it takes time to reduce the number of revolutions of the engine, and the time in the resonance band between the engine and the peripheral parts becomes long, which may cause noise and vibration.

  Therefore, it is an object of the present invention to allow the motor generator to function as a generator to reduce the engine speed even at extremely low temperatures.

A control device for a hybrid vehicle according to the present invention includes an engine, a motor generator, and a battery including a lithium-ion secondary battery. When the engine is stopped, the motor generator functions as a generator to generate electric power. A control device for a hybrid vehicle that inputs to the battery to reduce the number of revolutions of the engine, wherein a limit value of input power to the battery is calculated based on a charge / discharge history of the battery, and a negative electrode of the battery An input permission power adjustment unit that adjusts the input permission power to the battery so that the potential does not drop to the lithium reference potential, and an input from the motor generator to the battery by regenerative braking of the motor generator based on the temperature of the battery. The regenerative power limit value setting unit that sets the limit value of the regenerative power that is set, the absolute value of the limit value of the input power calculated by the input allowed power adjustment unit in the case where the temperature of the battery is a predetermined value or less, If the absolute value of the limit value of the regenerative power set by the regenerative power limit value setting unit is smaller than the absolute value, a regenerative braking prohibition unit that outputs a command to prohibit regenerative braking by the motor generator, and the battery the absolute value of the regenerative power limit value is input, characterized by numerical der Rukoto obtained by adding a predetermined margin to the absolute value of the maximum power value input from the motor generator when the engine is stopped.

  INDUSTRIAL APPLICABILITY The present invention can prevent the electric power that can be input to the battery from being greatly restricted at extremely low temperatures. This allows the motor generator to function as a generator and reduce the engine speed even at extremely low temperatures.

It is a block diagram which shows the structure of the control apparatus of the hybrid vehicle in the embodiment of this invention, and the structure of a hybrid vehicle. It is explanatory drawing which shows the charging time of a lithium ion secondary battery, and the transition of positive electrode potential and negative electrode potential. It is a schematic diagram which shows an example of a structure of a lithium ion secondary battery. It is a figure for demonstrating the amount of current recovery by leaving a lithium ion secondary battery in calculating an allowable input current value. It is a figure for demonstrating the structure of Formula (IV) which calculates | requires the limit value of the input electric power to a battery in the control apparatus of the hybrid vehicle of embodiment of this invention. 3 is a flowchart of charge / discharge control in the hybrid vehicle control device according to the embodiment of the present invention. 5 is a flowchart showing a regenerative prohibition operation of a regenerative braking prohibition unit in the hybrid vehicle control device according to the embodiment of the present invention. 7 is a flowchart showing a regenerative braking prohibition canceling operation of a regenerative braking prohibition unit in the hybrid vehicle control device according to the embodiment of the present invention. 6 is a map of a regenerative power limit value (regeneration prohibition threshold value) and a regeneration permission threshold value stored in a regenerative power limit value setting unit of the hybrid vehicle according to the embodiment of the present invention. It is a diagram showing a variation of the change and the battery power of the input power limit value W _in the battery (t) in the control unit for a hybrid vehicle of the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a hybrid vehicle 100 in which the control device 20 of the present embodiment is mounted will be described with reference to FIG. As shown in FIG. 1, a hybrid vehicle 100 includes an engine 58, a first motor-generator 52, a second motor-generator 54, a battery 10 including a lithium secondary battery, and a DC power of the battery 10. , And an inverter 50 that converts the AC power for driving the second motor generator and the AC power generated by the first and second motor generators into the DC power for charging the battery 10. The output shaft of the engine 58 and the output shafts of the first and second motor generators 52 and 54 are connected to the power distribution integration mechanism 56. The power distribution and integration mechanism 56 distributes the output torque of the engine 58 to the torque for driving the drive wheels 60 and the torque for causing the first and second motor generators to function as a generator, and at the same time, The output torque of the two-motor generators 52, 54 and the output torque of the engine 58 can be integrated and transmitted to the drive wheels 60. A voltage sensor 16 that detects the voltage of the battery 10 is attached between the battery 10 and the inverter 50. Further, a current sensor 14 that detects a charging / discharging current of the battery 10 (hereinafter, also referred to as “battery current”) is attached to the power line connected to the output terminal of the battery 10. A temperature sensor 12 that detects the temperature of the battery 10 is attached to the battery 10. The voltage sensor 16, the current sensor 14, and the temperature sensor 12 are connected to a battery ECU 22 of the control device 20 described later. The hybrid vehicle may be configured by one motor generator instead of providing two motor generators as in the present embodiment.

  The engine 58, the first motor generator 52, and the second motor generator 54 of the hybrid vehicle 100 configured as described above are adjusted in rotational speed, torque, and the like by the control device 20 described later. When starting the engine 58, the first motor generator 52 is caused to function as an electric motor to rotate the engine 58 in the drive direction. On the contrary, when the engine 58 is stopped, the first motor generator 52 is made to function as a generator to apply torque to the engine 58 in the opposite direction to the rotation direction. At this time, the battery 10 is charged with the electric power generated by the first motor generator 52 via the inverter 50.

  As shown in FIG. 1, the control device 20 according to the present embodiment includes a battery electronic control unit 22 (hereinafter, referred to as “battery ECU 22”) that monitors the state of the battery 10 and an SOC estimation unit that estimates the state of charge of the battery 10. 24, a motor electronic control unit 28 for driving and controlling the first motor generator 52 and the second motor generator 54 (hereinafter referred to as “motor ECU 28”), and various sensors for detecting the operating state of the engine 58. Electronic engine control unit 26 (hereinafter referred to as "engine ECU 26") that performs operation control such as fuel injection control, ignition control, and intake air amount adjustment control on the engine 58, and hybrid electronic control that controls the entire power output device The unit 30 (hereinafter referred to as "HVECU 30") and the input permission power to the battery 10 are adjusted based on the charging / discharging history during charging / discharging so that the negative electrode potential of the battery 10 made of a lithium ion secondary battery does not drop to the lithium reference potential. Input permission power adjusting unit 40, a regenerative power limit value setting unit 46 that sets a limit value of regenerative power according to the temperature of the battery 10, and a command that prohibits regenerative braking by the first and second motor generators 52 and 54. Is provided.

  As shown in FIG. 2, in the lithium ion secondary battery used as the battery 10, the positive electrode average potential increases while the negative electrode average potential decreases due to continuous charging, and the potential difference (Vav) between the positive and negative electrodes increases. .. Here, it is known that Li metal is deposited on the surface of the negative electrode when the negative electrode potential becomes equal to or lower than the Li reference potential (0 V). Therefore, when charging a lithium-ion secondary battery from the prior art, by suppressing the terminal voltage between the positive and negative electrodes, which is the potential difference of the average potential between the positive and negative electrodes, within a predetermined potential (for example, 4.1 V), Of Li metal is avoided.

  However, since there is reaction variation inside the cells of the battery (the surface of the positive and negative electrodes), it is assumed that the potential difference (Vav) of the positive and negative electrode average potentials is within the predetermined potential (Vlim), as after time t0 in FIG. Also, the negative electrode potential (referred to as the negative electrode local potential) at a local portion of the negative electrode may reach the Li reference potential (0 V) or less, and Li metal may be deposited on the corresponding negative electrode surface. In addition, such a Li metal deposition process includes high-rate (for example, 20 C or more) charging, charging from a high charging state (high SOC), continuous charging for a long time, and low temperature (state where battery cell internal resistance is high). It is likely to occur when charging in the field.

  Note that, as shown in FIG. 3, the cell potential is the potential difference between the positive electrode 74 and the negative electrode 76 in the cell of the lithium ion secondary battery, and the negative electrode potential is the potential difference between the negative electrode 76 and the Li reference electrode 78 (potential 0 V). And the positive electrode potential is the potential difference between the positive electrode 74 and the Li reference electrode 78 (potential 0 V). Further, it is conceivable to lower the positive electrode average potential so as not to fall below the Li reference potential, but in such a case, the required performance for the battery 10 may not be satisfied.

  Therefore, control device 20 in the present embodiment has input permission power adjustment unit 40 in order to locally prevent the negative electrode potential from reaching Li reference potential 0V.

  Next, each component of the control device 20 described above will be described in detail. As shown in FIG. 1, the battery ECU 22 supplies a signal necessary for managing the battery 10, for example, an inter-terminal voltage from a voltage sensor (not shown) installed between terminals of the battery 10 and a charge from the current sensor 14. The discharge current, the battery temperature TB from the temperature sensor 12 and the like are input and stored. The SOC estimation unit 24 also estimates the state of charge (SOC, remaining capacity) by integrating the battery current value IB (t) at the time t measured by the current sensor 14 input to the battery ECU 22. In addition, it is preferable to use the estimated current value corrected by the battery temperature value TB (t) measured at time t for the integration. Further, more accurate SOC estimation can be adopted by utilizing other information such as battery electromotive voltage.

The HVECU 30 is configured as a microprocessor centered on the CPU 32, and in addition to the CPU 32, a ROM 34 that stores a processing program, a RAM 36 that temporarily stores data, a timer 38, an input / output port and a communication port (not shown). With. The HVECU 30 receives an ignition signal from an ignition switch (not shown), a signal from an accelerator sensor (not shown), and signals from other sensors, and inputs information such as an accelerator opening degree, a brake depression amount, and a vehicle speed. Here, a torque command is determined in the HVECU 30 based on information such as the accelerator opening, the amount of brake depression, the vehicle speed, etc., and the HVECU 30 outputs the torque command to the motor ECU 28 and the engine ECU 26. The drive of the second motor generators 52 and 54 and the engine 58 is controlled. Further, the HVECU 30 is connected to the engine ECU 26, the motor ECU 28, and the battery ECU 22 via a communication port, and exchanges various control signals and data with the engine ECU 26, the motor ECU 28, and the battery ECU 22. Further, in the ROM 34, allowable input current values I _lim (t), I _lim '(t) calculated by the input allowable power adjustment unit 40 described later and the input power limit value W _in (t) of the battery 10 are calculated. A program for storing the battery current value IB (t) and the battery temperature value TB (t) output from the battery ECU 22 is temporarily stored in the RAM 36, and the input permission power adjusting unit 40 stores the program. The calculated allowable input current values I _lim (t), I _lim '(t) and the input power limit value W _in (t) of the battery 10 are also temporarily stored and data necessary for various calculations are stored.

  Further, the input allowed power adjustment unit 40 includes an allowable input current value calculation unit 42 and an input power limit value calculation unit 44, and the battery is determined based on the input power limit value Win (t) of the battery 10 obtained every 100 msec, for example. The input permission power to 10 is adjusted.

The allowable input current value calculation unit 42 outputs the battery current value IB (t) (hereinafter also referred to as “IB [t]”) and the battery temperature value TB (t at the time t output from the battery ECU 22 and temporarily stored in the RAM 36 of the HVECU 30. ) (Hereinafter also referred to as “TB [t]”) and the charge capacity value SOC (t) at the time t estimated by the SOC estimation unit 24, based on a program stored in the ROM 34 of the HVECU 30 during charging. Permissible input current value decrease amount F or f per unit time, or permissible input current value recovery amount F'or f'per unit time at the time of discharge (of F and (II ') of formula (I') described later) (corresponding to f), the allowable input current value recovery amount G or g per unit time due to leaving is calculated, and the allowable input current value I _lim (t) to the battery is calculated based on this. Here, the allowable input current value I _lim (t) is calculated based on the previously calculated allowable input current value I _lim (t−1) calculated last time, but the allowable input current value I _lim (0) set only for the first time is calculated. To use. The set allowable input current value I _lim (0) used only for the first time is obtained as the maximum current value at which Li metal does not deposit within a unit time when charged from a state where there is no influence of charge / discharge history.

In the present embodiment, during charging, allowable input current value calculation unit 42 calculates allowable input current value I _lim (t) (hereinafter, “I _lim [T]”, “I _lim ” by using the following equation). [T] "is also calculated. First, when there is no charge / discharge history, that is, only for the first time, it is obtained by the following formula (I). That is, from the allowable input current value I _lim (0) in the state where there is no charge / discharge history, the allowable input current value decrease amount F or the allowable input current value recovery amount F ′ due to the continuous charge / discharge, and the allowable input current value recovery amount G due to being left unattended. Subtract.

：充放電履歴の影響がない状態から充電した場合に、単位時間以内にＬｉ金属が析出しない最大電流

：履歴なしの状態から時間Ｔまで継続された充電による許容電流値減少項
（放電の場合は正となるため、回復項）

：時間による回復項 In formula (I), it is as follows.

: Maximum current at which Li metal does not deposit within a unit time when charged from a state where there is no effect of charge / discharge history

: Decrease term of allowable current value due to charging continued from no history state to time T (recovery term because it becomes positive in case of discharge)

: Recovery term by time

式中、Ｉ_lim［Ｔ］及びＩ_lim［ｔ］：時間Ｔ，ｔにおける許容入力電流値
ＩＢ［ｔ］：時間ｔにおけるバッテリ電流値
ＴＢ［ｔ］：時間ｔにおけるバッテリ温度値
ＳＯＣ［ｔ］：時間ｔにおけるバッテリＳＯＣ値
ｆ（）関数：単位時間当たりの充電による許容電流減少項
ｇ（）関数：放置による単位時間当たりの許容電流回復項 Further, when charging is in progress and there is a charge / discharge history, it is determined by the following formula (II).

In the formula, I _lim [T] and I _lim [t]: Allowable input current value at time T, t IB [t]: Battery current value at time t TB [t]: Battery temperature value at time t SOC [t] : Battery SOC value at time t f () function: Permissible current decrease term by charging per unit time g () function: Allowable current recovery term per unit time by leaving

When I _lim [t] = 0, it means that Li ions in the negative electrode active material of the battery 10 are in a saturated state. Therefore, I _lim [0] −I _lim [t] is the negative electrode active material of the battery 10. The amount of Li ion in is shown. On the other hand, as shown in FIG. 4, the amount of recovery of the allowable input current value with time is obtained by the decrease of Li ions in the negative electrode active material, and the size thereof is proportional to the amount of Li ions. Therefore, the relationship of I _lim [t-1] at time (t-1) before the unit time (dt) is proportional to the difference between I _lim [0] and I _lim [t-1], and further It can be obtained by dividing by I _lim [0] to make it dimensionless.

式中、Ｆ（）関数及びｆ（）関数：単位時間当たりの放電による許容電流回復項を示す以外は、上述同様であるためここでは説明を省略する。 On the other hand, when discharging, the signs of the function of F () and the function of f () in the expressions (I) and (II) change from minus to plus, respectively, as follows.

In the formula, the F () function and the f () function are the same as the above except that the allowable current recovery term by the discharge per unit time is shown, and therefore the description thereof is omitted here.

Further, in the present embodiment, in the allowable input current value calculation unit 42, I _lim [T] obtained from the above equation is taken into consideration in consideration of performance deterioration due to use, and further considering deterioration with time of Li metal deposition. ] And I _lim [t] are multiplied by the deterioration coefficient η to obtain I _lim '[T] and I _lim ' [t] in consideration of deterioration with time of the secondary battery.

I _lim '[T] = I _lim [T] × η, or
I _lim '[t] = I _lim [t] × η (III)
In the formula, η: deterioration coefficient.

  The deterioration coefficient η may be a constant value or a variable that changes based on a map that is stored in advance in the RAM 36 of the HVECU 30 and that includes the relationship between the charge / discharge frequency of the secondary battery and the deterioration coefficient.

Further, the input power limit value calculation unit 44 of the present embodiment aims to prevent the battery current value IB from flowing beyond I _lim '(t) due to a control delay of feedback control or the like. The input power limit value W _in (t) is calculated. That is, based on the battery current value IB (t) at the time t, which is output from the battery ECU 22 and temporarily stored in the RAM 36 of the HVECU 30, and the allowable input current value I _lim '(t) calculated by the allowable input current value calculation unit 42, For example, the input current limit target value I _tag is once calculated by offsetting it by a predetermined amount with respect to I _lim (t) (see FIG. 5). Then, the input power limit value W _in (t) of the battery 10 is calculated by the following equation (IV) based on the obtained I _tag .

As shown in FIG. 5, the input power limit value calculation unit 44 controls the charging by the input power limit value W _in (t) obtained by the equation (IV), so that the battery current value IB _becomes I _lim '(t). In the following, it becomes possible to suppress Li metal from being deposited on the negative electrode 76.

W _in (t) = SW _in (t)
−K _p × {IB (t) −I _tag1 (t)}
−K _i × ∫ {IB (t) −I _tag2 (t)} dt (IV)

In the formula, W _in (t): Battery input power limit value (W) at time t
SW _in (t): A preset battery input power limit value (for example, a base input power limit value of the battery 10 determined from the battery temperature)
K _p: p to claim feedback gain K _i: i claim feedback gain I _tag1 (t): p claim Feedback control current limit target value I _tag2 by (t): i term feedback control by the current limit target value IB (t): time Battery current value at t

Note that SW _in (t) is obtained by, for example, a preset map of the relationship between the temperature of the battery 10 and the specified input power limit value.

Further, the I _tag1 (t) and I _tag2 (t) is obtained by the following formula (V).

I _tag1 (t) = F _p (I _lim '(t)), and
I _tag2 (t) = F _i (I _lim '(t)) (V)

In formula _{(V), I tag1 (t} ) and I _tag2 (t), compared I _lim '(t) as described above, are respectively calculated as an amount obtained by offsetting by a predetermined amount. Therefore, it is an I _tag1, I _tag2, pre-stored as a map of the relationship between I _lim '(t) to RAM36 of HV ECU 30, when referring to this seek I _tag1, I _tag2. In addition, by preparing a map in consideration of deterioration of the secondary battery and control of the secondary battery, it is possible to further suppress Li metal deposition due to a local decrease in the negative electrode potential.

  In addition, control device 20 in the present embodiment controls the upper limit voltage of the lithium-ion secondary battery so as not to exceed a preset upper limit voltage in order to suppress performance deterioration due to use of battery 10, and upper limit voltage control. You may further have a part. As the upper limit voltage control unit, for example, in the HVECU 30, a preset upper limit voltage value is compared with an actual battery voltage value output from a voltage sensor (not shown) to control the charge amount. By thus setting the upper limit of the charging voltage, it becomes possible to prevent an unreasonably large voltage from being applied to the cell.

  Next, the charge / discharge control operation of battery 10 in hybrid vehicle 100 having control device 20 in the present embodiment will be described below with reference to FIGS. 1 and 6. First, the temperature sensor 12 measures the battery temperature value TB (t) at time t, and the current sensor 14 measures the battery current value IB (t) at time t (step S110 in FIG. 6). The battery ECU 22 stores the battery temperature value TB (t) output from the temperature sensor 12 at the time t and the battery current value IB (t) output from the current sensor 14 at the time t, and stores it in the SOC estimation unit 24. The battery temperature value TB (t) and the battery current value IB (t) at the time t are output, and the battery temperature value TB (t) and the battery current value IB (t) at the time t are output to the HVECU 30. The RAM 36 of the HVECU 30 temporarily stores the battery temperature value TB (t) and the battery current value IB (t) at the input time t. The SOC estimation unit 24 estimates the charging capacity value SOC (t) at time t based on the input battery temperature value TB (t) and battery current value IB (t) at time t (step S112 in FIG. 6). ).

Next, when it is determined that the HVECU 30 is regenerating from the accelerator opening degree, the amount of brake depression, the vehicle speed, and the like (step S114 in FIG. 6), charging of the regenerative energy to the battery 10 is started. The allowable input current value calculation unit 42 calculates the allowable input current value I _lim (t) using the above formula (I) or formula (II) (step S118 in FIG. 6), and further calculates the formula (III). The allowable input current value I _lim '(t) is calculated by using the deterioration of the secondary battery with time (step S120 in FIG. 6).

Further, based on the allowable input current value I _lim '(t) output by the allowable input current value calculation unit 42 and the actual battery current value IB (t) at time t, the input power limit value calculation unit 44 The input power limit value W _in (t) is calculated using the equations (IV) and (V) (step S122 in FIG. 6). That is, the amount of decrease in the allowable input current value I _lim (t) due to continuous charging (the amount of decrease due to the F term) is updated. Then, the input power to the battery 10 is limited to the calculated input power limit value W _in (t) (step S124 in FIG. 6). That is, the HVECU 30 determines the motor torque command and controls the inverter 50 via the motor ECU 28. At this time, the motor torque command (charge) is controlled so that the input power to the battery 10 becomes W _in (t) or less. Adjust the negative torque command).

  Further, although the regeneration is not being performed, even when the charging request is generated based on the SOC of the battery 10, the above-described operations of step S118 to step S124 of FIG. 6 are performed. In this case, the power generated by the second motor generator 54 is normally supplied to the battery 10.

Further, when the battery 10 is not being recharged and is not being charged during traveling, the allowable input current value calculation unit 42 uses the above-described formula (I ′) or formula (II ′) to determine the allowable input current value I _lim. (T) is calculated (step S126 in FIG. 6), and the allowable input current value I _lim ′ (t) considering the deterioration of the secondary battery over time is calculated using the formula (III) (FIG. 6). Step S128). That is, the amount of recovery of the allowable input current value I _lim (t) due to the continuation of discharge (the amount of recovery by the F term) or the increase by leaving it (the amount of recovery by the G term) is updated.

Further, based on the allowable input current value I _lim '(t) updated by the allowable input current value calculation unit 42 at the time of discharging or leaving and the actual battery current value IB (t) at the time t, The input power limit value calculation unit 44 calculates the input power limit value W _in (t) using the equations (IV) and (V) (step S122 in FIG. 6). Further, based on the calculated input power limit value W _in (t), the input permitted power to the battery 10 is limited (step S124 in FIG. 6). Here, since the battery 10 is not charged during discharging or leaving, the input power limit value W _in (t) is simply updated to drive the first and second motor generators 52, 54 ( The output torque) control is performed regardless of the input power limit value W _in (t).

By being controlled as described above, the input power to the battery 10 is obtained by performing feedback control according to the battery current value IB on SW _in (t) which is the base power value of the input power limit specified value. become. Then, in this feedback control, a predetermined offset (control margin) is _added to the allowable input current value I _lim (t) for preventing metal lithium from being deposited or I _lim '(t) considering battery deterioration. are those corresponding to the I _tag1 (t) or I _tag2 (t), by a control delay due to feedback control, effectively that the battery current value IB exceeds the I _tag1 (t) or I _tag2 (t) Can be prevented. Furthermore, I _tag1 (t) (or I _tag2 (t)) takes into account the history of charging and discharging. That is, as shown in the formulas (I), (II), (I '), (II'), and (III), the allowable input current decreases and recovers based on the charging / discharging duration time, and the allowable input current recovers when left unattended. Are considering. Therefore, it is possible to prevent the deposition of metallic lithium according to the state of the battery 10 at that time.

Here, referring to FIG. 10, changes in the output power (discharge power) and the input power (charge power) of the battery 10 due to the above-described operation, that is, the time change of the battery power (charge / discharge power) and the battery 10 An example of the temporal change of the input power limit value W _in (t) of will be described. In FIG. 10, the solid line c shows the time change of the battery power (charge / discharge power), and the alternate long and short dash line d shows the time change of the input power limit value W _in (t) of the battery 10. Note that here, the change from time 0 to immediately before time t2 will be described. The change after time t2 will be described later.

In the vicinity of time 0 in FIG. 10, the battery 10 is repeatedly charged and discharged, and the allowable input current value I _lim (t) is alternately decreased and recovered. Therefore, the input power limit value W _in (t) of the battery 10 is the battery input power limit specified value SW _in (t) that is predetermined based on the temperature of the battery 10 and the like. Then, as shown in FIG. 10, when electric power is continuously input to the battery 10 due to regenerative braking or the like, as described with reference to FIG. 5, the allowable input current values I _lim (t), I _tag The absolute value of (t) becomes smaller, and after time t1 shown in FIGS. 5 and 10, as indicated by the alternate long and short dash line d in FIG. 10, the absolute value of the input power limit value W _in (t) is the battery input power limit regulation. It is limited to be smaller than the absolute value of the value SW _in (t).

If the input of electric power to the battery 10 due to regenerative braking or the like continues after time t1 shown in FIG. 10, the absolute value of the allowable input current value I _lim (t) continuously decreases. Therefore, the alternate long and short dash line in FIG. As shown in d, the absolute value of the input power limit value W _in (t) decreases with time. As indicated by the solid line c in FIG. 10, the battery power (charging / discharging power) is controlled by the control device 20 so as not to exceed the input power limit value W _in (t). The absolute value gradually decreases.

  Next, the regenerative power limit value setting unit 46 of the control device 20 of the present embodiment will be described. The regenerative power limit value setting unit 46 includes a regenerative prohibition threshold value (kW) which is a limit value of regenerative power according to the battery temperature TB as shown by a solid line a in FIG. 9 and a battery as shown by a chain line b in FIG. The map of the regeneration permission threshold value (kW) for releasing the prohibition of the regenerative braking according to the temperature TB is stored. Both the regeneration inhibition threshold value (kW) and the regeneration permission threshold value (kW) are negative values. The temperature T0 shown in FIG. 9 is, for example, about −10 to −15 ° C. As shown in FIG. 1, the regenerative electric power limit value setting unit 46 is connected to the battery ECU 22 and the regenerative braking prohibition unit 48, and the regeneration prohibition threshold value (kW) and the regeneration permission according to the battery temperature TB input from the battery ECU 22. The threshold value (kW) is output to the regenerative braking prohibition unit 48.

The regeneration prohibition threshold value is a numerical value obtained by adding a predetermined margin to the maximum electric power value input from the first motor generator 52 when the engine is stopped when the battery 10 is in an extremely low temperature state of −10 to −15 ° C. or lower. Yes, for example-a value of a few kW. Further, as indicated by the solid line a and the alternate long and short dash line b in FIG. 9, the absolute values of the set values of the regeneration inhibition threshold value (kW) and the regeneration permission threshold value (kW) increase as the temperature of the battery 10 decreases. This is because as the temperature of the lithium secondary battery becomes lower, the deposition of lithium metal is more likely to occur. Therefore, as the temperature of the battery 10 becomes lower, regenerative braking is prohibited while the absolute value of the input power limit value W _in (t) is large. This is to increase the margin of the inputtable electric power of the battery 10.

The absolute value of the regeneration permission threshold value is slightly larger than the absolute value of the regeneration prohibition threshold value, and the absolute value of the input power limit value W _in (t) of the battery 10 becomes large due to a neglected state due to regeneration prohibition, discharge, or the like. This is a threshold value for canceling the regenerative braking prohibition command when it comes.

The regenerative braking prohibition unit 48 is connected to the battery ECU 22, the regenerative power limit value setting unit 46, and the input power limit value calculation unit 44 in the input permission power adjustment unit 40, and determines the battery temperature TB input from the battery ECU 22. Accordingly, the regeneration prohibition threshold value and the regeneration permission threshold value input from the regenerative power limit value setting unit 46 are compared with the input power limit value W _in (t) input from the input power limit value calculation unit 44, and regenerative braking is performed. A command to prohibit and a command to cancel the prohibition of regenerative braking are output to the HVECU 30.

  The operation of the regenerative braking prohibition unit 48 will be described below with reference to FIGS. 7 and 8.

The regenerative braking prohibition unit 48 measures the battery temperature TB via the battery ECU 22 (step S210 in FIG. 7). Then, it is determined whether or not the battery temperature TB is equal to or lower than a predetermined threshold value, for example, an extremely low temperature state of about −10 to −15 ° C. (step S212 in FIG. 7). When it is determined as Yes in step S212 of FIG. 7, the process proceeds to step S214 of FIG. 7 and the regenerative power limit value setting unit 46 acquires the regenerative prohibition threshold value that is the regenerative power limit value. Then, the process proceeds to step S216 of FIG. 7, and the input power limit value W _in (t) of the battery 10 is acquired from the input power limit value calculation unit 44. Then, the process proceeds to step S218 in FIG. 7, the absolute value and compares the absolute value of the regeneration prohibition threshold, the absolute value of regeneration prohibition threshold input power limit value W _in (t) of the input power limit value W _in (t) If it is smaller than the absolute value of, the process proceeds to step S220 in FIG. 7, and a command to prohibit the regenerative braking by the first and second motor generators 52 and 54 is output to the HVECU 30. As a result, the HVECU 300 prohibits regenerative braking by the first and second motor generators 52 and 54 and switches to braking by hydraulic braking.

On the other hand, when the battery temperature TB is not lower than the predetermined threshold value, the battery 10 is not in the extremely low temperature state, and when it is determined No in step S212 of FIG. 7, it is determined that normal regenerative braking is possible and regenerative braking is performed. The routine ends without prohibition. Further, when the absolute value of the input power limit value W _in (t) is not smaller than the absolute value of the regeneration prohibition threshold, the battery 10 receives the electric power input from the first motor generator 52 when the engine is stopped. Is determined to be acceptable, the regenerative braking is not prohibited, and the routine ends (step S218 in FIG. 7).

Further, as shown in FIG. 8, the regenerative braking prohibition unit 48 outputs a command for canceling the regenerative braking prohibition output by the routine described with reference to FIG. 7. As shown in FIG. 8, the regenerative braking prohibition unit 48 acquires the battery temperature TB, and when the battery temperature TB is equal to or lower than a predetermined threshold value (steps S310 and S312 in FIG. 8), the regenerative power limit value setting unit 46. The regenerative permission threshold value (kW) is acquired from the input power limit value calculation unit 44 and the input power limit value W _in (t) is acquired from the input power limit value calculation unit 44 (steps S314 and S316 in FIG. 8). Then, the process proceeds to step S318 of FIG. 8, the absolute value and compares the absolute value of the regeneration permission threshold, the absolute value of the regeneration permission threshold input power limit value W _in (t) of the input power limit value W _in (t) If it is larger than the absolute value of, the process proceeds to step S320 of FIG. 8 and the HVECU 30 is instructed to release the command to prohibit the regenerative braking by the first and second motor generators 52 and 54.

  If the battery temperature TB exceeds the predetermined threshold value, the regenerative braking prohibition unit 48 determines No in step S312 of FIG. 8, proceeds to step S320 of FIG. 8, and proceeds to the first and second motor generators 52, A command for canceling the command for prohibiting the regenerative braking by 54 is output to HVECU 30.

Next, changes _{in the} input power limit value W _in (t) and changes in the battery power due to the operations of the regenerative braking prohibition unit 48 and the input permission power adjustment unit 40 will be described with reference to FIG. 10. Hereinafter, the temperature of the battery 10 will be described as being in an extremely low temperature state below a predetermined threshold value (for example, −10 to −15 ° C.).

As described above, when the input of the electric power to the battery 10 by the regenerative braking or the like continues until the time t1 shown in FIG. 10, the absolute value of the allowable input current value I _lim (t) continuously decreases. As shown by the alternate long and short dash line d in FIG. 10, the absolute value of the input power limit value W _in (t) decreases with time. Since the temperature of the battery 10 is in the extremely low temperature state below a predetermined temperature, the regenerative braking prohibition unit 48 sets the regenerative power limit value setting unit 46 to the regenerative prohibition threshold value (kW) and the input power limit value calculation unit 44 to the input power limit value W. _in (t) is acquired, and the absolute value of the input power limit value W _in (t) is compared with the absolute value of the regeneration prohibition threshold value. Before time t2 shown in FIG. 10, the absolute value of the input power limit value W _in (t) is larger than the absolute value of the regenerative prohibition threshold, so the regenerative braking prohibition unit 48 issues a command to the HVECU 30 to prohibit regenerative braking. Do not output. Therefore, the HVECU 30 continues the regenerative braking by the first and second motor generators 52 and 54.

Further, when regenerative braking is continued, the absolute value of the input power limit value W _in (t) further decreases with time, and at time t2, the absolute value of the input power limit value W _in (t) becomes the absolute value of the regeneration prohibition threshold value. Will be smaller than. Therefore, the regenerative braking prohibition unit 48 determines Yes in step S218 of FIG. 7, and outputs a command to prohibit regenerative braking to the HVECU 30 as shown in step S220 of FIG.

When this command is input, the HVECU 30 controls so that the first and second motor-generators 52 and 54 do not perform regenerative braking, but only hydraulic braking. Therefore, as indicated by the solid line c in FIG. 10, the input power to the battery 10 becomes zero after the time t2. When the input power to the battery 10 becomes zero, the battery 10 is left in a neglected state, and the absolute value of the recovery term (g () function in the formula (II)) of the allowable power with time increases, so that the chain line d in FIG. As shown in, the absolute value of the input power limit value W _in (t) also increases after time t2.

Further, since the temperature of the battery 10 is an extremely low temperature equal to or lower than the predetermined threshold value, the regenerative braking prohibition unit 48 sets the absolute value of the input power limit value W _in (t) and the regeneration permission threshold value as shown in step S318 of FIG. Comparing with absolute value. Then, when the absolute value of the input power limit value W _in (t) becomes larger than the absolute value of the regeneration permission threshold value at time t3 in FIG. 10, the regenerative braking prohibition unit 48 causes the regenerative braking as shown in step S320 in FIG. A command for canceling the braking prohibition is output to HVECU 30. When this command is input, the HVECU 30 performs regenerative braking within a range that does not exceed the input power limit value W _in (t) when the first and second motor generators 52 and 54 request regenerative braking. .. When regenerative braking is restarted and power is input to the battery 10, the absolute value of the input power limit value W _in (t) becomes smaller again.

As described above, the regenerative braking prohibition unit 48 outputs the regenerative braking prohibition command, so that the absolute value of the input power limit value W _in (t) of the battery 10 does not greatly fall below the regenerative prohibition threshold value. The regeneration prohibition threshold value is a numerical value obtained by adding a predetermined margin to the maximum electric power value input from the first motor generator 52 when the engine is stopped when the battery 10 is in an extremely low temperature state of −10 to −15 ° C. or lower. Therefore, during the stop operation of the engine 58 started at time t5 in FIG. 10, the first motor generator 52 is caused to function as a generator from time t5 to time t6 shown in FIG. Can be input to the battery 10 to reduce the rotation speed of the engine 58. In the engine stop operation, from time t6 to time t7, the first motor generator 52 functions as an electric motor to apply torque in the same direction as the rotation direction to the engine 58 so that the engine 58 does not rotate in the reverse direction. Then, the engine 58 is stopped at time t7 in FIG.

  As described above, the control device 20 according to the present embodiment limits the inputtable electric power to the battery 10 to the maximum electric power value or more input from the first motor generator 52 when the engine is stopped at the extremely low temperature. Even when the temperature is extremely low, the first motor-generator 52 can be made to function as a generator to reduce the rotation speed of the engine 58. As a result, it is possible to shorten the time for lowering the rotation speed of the engine 58 and shorten the time in the resonance band between the engine 58 and the peripheral parts, and suppress the generation of sound and vibration.

Further, in the present embodiment, as shown in the map of FIG. 9, the regeneration inhibition threshold value and the regeneration permission threshold value are set such that the absolute values thereof increase as the battery temperature TB decreases. As a result, the lower the battery temperature TB is, the larger the absolute value of the input power limit value W _in (t) is controlled, and the remaining power of the input power to the battery 10 is increased. This makes it possible to more effectively suppress the deposition of lithium metal in the battery 10 and cause the first motor-generator 52 to function as a generator when the engine is stopped to reduce the rotation speed of the engine 58.

10 battery, 12 temperature sensor, 14 current sensor, 16 voltage sensor, 20 control device, 22 battery electronic control unit (battery ECU), 24 SOC estimation unit, 26 engine electronic control unit (engine ECU),
28 Motor Electronic Control Unit (Motor ECU), 30 Hybrid Electronic Control Unit (HVECU), 40 Input Allowed Power Adjustment Unit, 42 Allowable Input Current Value Calculation Unit, 44 Input Power Limit Value Calculation Unit, 46 Regenerative Power Limit Value Setting Part, 48 regenerative braking prohibition part, 50 inverter, 52 first motor generator, 54 second motor generator, 56 power distribution integration mechanism, 58 engine, 60 driving wheels, 74 positive electrode, 76 negative electrode, 78 reference electrode, 100 hybrid vehicle.

Claims (1)

An engine, a motor generator, and a battery including a lithium-ion secondary battery are provided, and when the engine is stopped, the motor generator functions as a generator to input generated power to the battery to rotate the engine. A control device for a hybrid vehicle that reduces the number of
Input permission power that calculates the limit value of the input power to the battery based on the charge / discharge history of the battery and adjusts the input permission power to the battery so that the negative electrode potential of the battery does not drop to the lithium reference potential. The adjustment section,
A regenerative power limit value setting unit that sets a limit value of regenerative power input from the motor generator to the battery by regenerative braking of the motor generator based on the temperature of the battery;
When the temperature of the battery is equal to or lower than a predetermined value, the absolute value of the limit value of the input power calculated by the input permission power adjusting unit is the absolute value of the limit value of the regenerative power set by the regenerative power limit value setting unit. If it is smaller than the value, a regenerative braking prohibition unit that outputs a command to prohibit regenerative braking by the motor generator ,
The absolute value of the regenerative power limit value input to the battery, the maximum power value of the absolute value to a predetermined margin numerical der Ru control apparatus for a hybrid vehicle plus input from the motor generator when the engine is stopped ..

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