JP4706493B2 - Control device for secondary battery mounted on vehicle - Google Patents

Description

  The present invention relates to a secondary battery (hereinafter simply referred to as “battery” in some cases) mounted on a vehicle, and more particularly to a control device capable of realizing excellent charge / discharge characteristics even in a low temperature state.

  For example, in a hybrid vehicle including an engine, a generator driven during regenerative braking of the engine or driving wheels, and a traveling motor, an SOC (State Of Charge) representing a remaining capacity of a battery that is a power source of the motor As an index, power generation by the generator is controlled so that the SOC is maintained within a predetermined range. In such a vehicle, since the motor is driven by the electric power from the battery, the input / output power of the battery greatly affects the running performance of the vehicle. There are various factors that decrease the input / output power of the battery, but the phenomenon that the input / output power decreases as the temperature decreases has a particularly great influence.

  Thus, in cold districts and the like, measures are taken to ensure the running performance of the vehicle by raising the temperature of the battery with a heater device, thereby suppressing a decrease in the input / output power of the battery. Such countermeasures require the addition of components such as a heater device, which causes adverse effects such as an increase in vehicle manufacturing costs and a complicated structure, and a part of the heat generated by the heater device other than the battery. There is room for improvement in terms of energy efficiency.

  Japanese Patent Application Laid-Open No. 2003-272712 discloses a battery control capable of preventing a decrease in battery input / output power due to a decrease in temperature by efficiently increasing the temperature of a battery while avoiding adverse effects due to the addition of components. An apparatus is disclosed. The battery control device includes battery temperature detection means for detecting the temperature of the battery, charge state determination means for determining the charge state of the battery, and battery control means for controlling charge / discharge of the battery. When the battery temperature detected by the battery temperature detection means is below a predetermined value and the battery charge state determined by the charge state determination means is greater than or equal to a preset threshold value, the battery control means The battery is repeatedly charged and discharged within a predetermined area that is equal to or greater than the threshold value. When the state of charge of the battery is less than the threshold, the battery is repeatedly charged and discharged within the predetermined area that is less than the threshold. Further, the battery control means prohibits the drive of the generator by the engine during discharge control within a predetermined area during travel, and permits the drive of the generator by the engine during charge control within the predetermined area during travel. . Further, the battery control means drives the generator while the vehicle is stopped.

According to this battery control device, when the temperature of the battery is equal to or lower than a predetermined value and the charge state of the battery is equal to or higher than the threshold value, the charge / discharge of the battery is repeated within a predetermined region equal to or higher than the threshold value. Is less than the threshold value, the battery is repeatedly charged and discharged within a predetermined region below the threshold value. In a region divided into two with the threshold as a boundary, charging / discharging of the battery is alternately repeated in a short cycle, and the temperature is quickly raised. Further, the battery control means drives the generator while the vehicle is stopped, so that when the vehicle stops during discharge control or charge control, the generator is driven and electric power is supplied to the battery. If the vehicle is stopped, charging and discharging of the battery will not occur and it will be difficult to raise the battery temperature. By charging the battery by driving the generator in this way, the battery temperature can be raised. It becomes.
JP 2003-272712 A

  However, in the battery control device of Patent Document 1 described above, when the SOC reaches the upper limit value when the vehicle is stopped, the battery cannot be charged or discharged by driving the generator. For this reason, sufficient temperature rising effect cannot be expressed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for a secondary battery mounted on a vehicle, which can realize good charge / discharge characteristics even in a low temperature environment. Is to provide.

  A control device according to a first aspect of the invention controls a secondary battery mounted on a vehicle including an engine that drives the vehicle and a rotating electrical machine that generates electric power using the driving force of the engine. The control device includes a temperature detection unit for detecting the temperature of the secondary battery, a charge state detection unit for detecting the charge state of the secondary battery, and a control unit for controlling charge / discharge of the secondary battery. Including. This control means is a case where the charge prohibition range and the discharge prohibition range are respectively determined according to the charge amount of the secondary battery, and the temperature of the secondary battery is lower than a predetermined threshold value, and In the case where the charge amount of the secondary battery is not in the charge prohibition range and the discharge prohibition range, a means for controlling to prioritize discharge during traveling of the vehicle and charge while the vehicle is stopped is included.

  According to the first invention, when the temperature of the secondary battery is detected and the temperature is lower than a predetermined temperature, Joule heat is generated by the charge / discharge current by positively charging / discharging the secondary battery. To raise the temperature of the secondary battery. In such a low temperature state, when the state of charge of the secondary battery (SOC) has already reached the control upper limit SOC at the time of stoppage, charging cannot be performed (since the vehicle is not running, power is supplied to the running motor. Can not be discharged). For this reason, in the case where the temperature of the secondary battery is lower than a predetermined threshold value and the charge amount (charge state: SOC) of the secondary battery is not in the charge prohibition range and the discharge prohibition range. Is controlled so that the secondary battery can be charged using the electric power generated by the rotating electrical machine when the vehicle is stopped so that the secondary battery is discharged preferentially while the vehicle is running. In this way, the secondary battery is charged when the vehicle is stopped. For this reason, a charging current flows into the secondary battery, and the secondary battery can be heated by Joule heat generated by the internal resistance of the secondary battery. For this reason, it is possible to avoid a decrease in the power that can be input / output as the temperature of the secondary battery decreases. As a result, it is possible to provide a control device for a secondary battery mounted on a vehicle that can realize good charge / discharge characteristics even in a low temperature environment.

  In the control device for the secondary battery mounted on the vehicle according to the second invention, in addition to the configuration of the first invention, the control means supplies the electric power discharged from the secondary battery to the electric motor for traveling. And means for controlling the vehicle to travel.

  According to the second invention, while the vehicle is traveling, the electric power discharged from the secondary battery is supplied to the traveling motor and the vehicle is traveled (EV traveling), or the engine is assisted by the traveling motor. During traveling before the vehicle stops, the power of the secondary battery is used as a driving source of the vehicle, and the SOC of the secondary battery is lowered. For this reason, the secondary battery can be charged using the electric power generated by the rotating electrical machine while the vehicle is stopped.

  In the control device for the secondary battery mounted on the vehicle according to the third aspect of the invention, in addition to the configuration of the second aspect, the traveling motor is a rotating electric machine.

  According to the third invention, the motor generator that functions as an electric motor (motor) for traveling and also functions as a generator (generator) driven by the engine is mounted on the vehicle. While the vehicle is running, the motor generator is caused to function as a motor, and the vehicle is run using the electric power discharged from the secondary battery to lower the SOC of the secondary battery. While the vehicle is stopped, the motor generator functions as a generator to generate electricity and charge the secondary battery. For this reason, since the charging / discharging current of the secondary battery flows both when the vehicle is running and when it is stopped, the temperature of the secondary battery can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A control block diagram of a hybrid vehicle according to an embodiment of the present invention will be described with reference to FIG. The present invention is not limited to the hybrid vehicle shown in FIG. In the present invention, an internal combustion engine such as a gasoline engine (hereinafter referred to as an engine) as a power source may be a drive source for driving a vehicle and a generator drive source. Furthermore, the drive source is an engine and a motor generator, and any vehicle that can travel with the power of the motor generator (whether the engine is stopped or not stopped) may be used. (It is not limited to so-called series type or parallel type hybrid vehicles). This battery is a nickel metal hydride battery or a lithium ion battery, and the type thereof is not particularly limited.

  The hybrid vehicle includes an engine 120 and a motor generator (MG) 140. In FIG. 1, for convenience of explanation, the motor generator 140 is expressed as a motor 140A and a generator 140B (or a motor generator 140B). However, depending on the traveling state of the hybrid vehicle, the motor 140A functions as a generator, The generator 140B functions as a motor. Regenerative braking is performed when this motor generator functions as a generator. When the motor generator functions as a generator, the kinetic energy of the vehicle is converted into electric energy, and the vehicle is decelerated. The drive source may be only the engine 120, and the motor generator 140 may function only as a generator driven by the engine 120.

  In addition to this, the hybrid vehicle transmits the power generated by the engine 120 and the motor generator 140 to the drive wheels 160, the reduction gear 180 that transmits the drive of the drive wheels 160 to the engine 120 and the motor generator 140, and the engine 120 A power split mechanism (for example, a planetary gear mechanism) 200 that distributes the generated power to two paths of the drive wheel 160 and the generator 140B, a travel battery 220 that charges power for driving the motor generator 140, and a travel An inverter 240 that performs current control while converting a direct current of battery 220 and an alternating current of motor 140A and generator 140B, and a battery control unit that manages and controls a charge / discharge state (for example, SOC (State Of Charge)) of traveling battery 220 (Hereafter, the battery ECU (Electronic Co ntrol unit) 260, engine ECU 280 for controlling the operating state of engine 120, MG_ECU 300 for controlling motor generator 140, battery ECU 260, inverter 240, etc. according to the state of the hybrid vehicle, battery ECU 260, engine ECU 280, and MG_ECU 300 HV_ECU 320 that controls the entire hybrid system so that the hybrid vehicle can operate most efficiently.

  In the present embodiment, boost converter 242 is provided between battery for traveling 220 and inverter 240. This is because the rated voltage of the traveling battery 220 is lower than the rated voltage of the motor 140A or the motor generator 140B, and therefore when the power is supplied from the traveling battery 220 to the motor 140A or the motor generator 140B, the boost converter 242 supplies the power. Boost the pressure.

  In FIG. 1, each ECU is configured separately, but may be configured as an ECU in which two or more ECUs are integrated (for example, MG_ECU 300 and HV_ECU 320 are integrated as shown by a dotted line in FIG. 1). An example of this is the ECU.

  The power split mechanism 200 uses a planetary gear mechanism (planetary gear) in order to distribute the power of the engine 120 to both the drive wheel 160 and the motor generator 140B. By controlling the rotation speed of motor generator 140B, power split device 200 also functions as a continuously variable transmission. The rotational force of the engine 120 is input to the planetary carrier (C), which is transmitted to the motor generator 140B by the sun gear (S) and to the motor and the output shaft (drive wheel 160 side) by the ring gear (R). When the rotating engine 120 is stopped, since the engine 120 is rotating, the kinetic energy of this rotation is converted into electric energy by the motor generator 140B, and the rotational speed of the engine 120 is reduced.

  In a hybrid vehicle equipped with a hybrid system as shown in FIG. 1, when a predetermined condition is established for the state of the vehicle, HV_ECU 320 causes motor 140A to run the hybrid vehicle only by motor 140A of motor generator 140. And engine 120 is controlled via engine ECU280. For example, the predetermined condition is a condition that the SOC of traveling battery 220 is equal to or greater than a predetermined value. In this way, the hybrid vehicle can be driven only by the motor 140A of the motor generator 140 when the engine 120 is inefficient at the time of starting or at low speed. As a result, the SOC of the traveling battery 220 can be reduced (the traveling battery 220 can be charged when the vehicle is subsequently stopped).

  Further, during normal travel, for example, the power split mechanism 200 divides the power of the engine 120 into two paths, and on the other hand, the drive wheels 160 are directly driven, and on the other hand, the generator 140B is driven to generate power. At this time, the motor 140A is driven by the generated electric power to assist driving of the driving wheels 160. Further, at the time of high speed traveling, electric power from the traveling battery 220 is further supplied to the motor 140A to increase the output of the motor 140A and to add driving force to the driving wheels 160. On the other hand, at the time of deceleration, motor 140 </ b> A driven by drive wheel 160 functions as a generator to perform regenerative power generation, and the collected power is stored in traveling battery 220. When the amount of charge of traveling battery 220 decreases and charging is particularly necessary, the output of engine 120 is increased to increase the amount of power generated by generator 140B to increase the amount of charge for traveling battery 220.

  In addition, the target SOC of traveling battery 220 is normally set to about 60% so that energy can be recovered no matter when regeneration is performed. Further, the upper limit value and the lower limit value of the SOC are set, for example, with the upper limit value set to 80% and the lower limit value set to 30% in order to suppress the deterioration of the battery of the traveling battery 220. The HV_ECU 320 is set via the MG_ECU 300. Thus, power generation and regeneration by the motor generator 140 and motor output are controlled so that the SOC does not exceed the upper limit value and the lower limit value. In addition, the value quoted here is an example and is not a particularly limited value. In particular, in the following description, the control SOC upper limit is 65%, and the control SOC lower limit is 50%.

  In such a hybrid vehicle configuration, the present invention generates power by rotating the motor generator 140 by the engine 120 even in a low temperature environment even when the vehicle is stopped. The temperature of the traveling battery 220 is raised by actively executing the generated power to the traveling battery 220.

  A control structure of a program executed by HV_ECU 320 which is the battery control device according to the present embodiment will be described with reference to FIGS. 2 and 3. The program (subroutine) shown in this flowchart is repeatedly executed with a predetermined cycle time (for example, 80 msec).

  In step (hereinafter, step is described as S) 100, HV_ECU 320 detects the SOC and vehicle speed V.

  In S200, HV_ECU 320 determines whether or not the SOC is less than 50%. If the SOC is less than 50% (YES in S200), the process proceeds to S300. If not (NO in S200), the process proceeds to S400. Thereafter, the process proceeds to S600. In S300, HV_ECU 320 turns on (sets) the discharge prohibition flag. Thereafter, the process proceeds to S600.

  In S400, HV_ECU 320 determines whether or not the SOC is higher than 52%. If the SOC is higher than 52% (YES in S400), the process proceeds to S500. If not (NO in S400), the process proceeds to S600. In S500, HV_ECU 320 turns off (resets) the discharge prohibition flag. Thereafter, the process proceeds to S600.

  In S600, HV_ECU 320 determines whether or not the SOC is higher than 65%. If the SOC is higher than 65% (YES in S600), the process proceeds to S700. If not (NO in S600), the process proceeds to S800. In S700, HV_ECU 320 turns on (sets) the charge prohibition flag. Thereafter, the process proceeds to S1000.

In S800, HV_ECU 320 determines whether or not the SOC is less than 63%. If the SOC is less than 63% (YES in S800), the process proceeds to S900. If not (NO in S800), the process proceeds to S1000. In S900, HV_ECU 320 turns off (resets) the charge prohibition flag. After that, the process is S
1000.

  Note that the SOC threshold value in S100 to S800 is an example, and the present invention is not limited to such a value. In particular, 52% of S400 is a value obtained by adding ΔT (1) (here 2%) to the control SOC lower limit value, and 63% of S800 is ΔT (2) (here 2%) as the control SOC upper limit value. Is not necessarily assumed to be equal to ΔT (1) and ΔT (2).

  In S1000, HV_ECU 320 determines whether vehicle speed V is zero or not. If vehicle speed V is 0 (YES in S1000), the process proceeds to S1100. If not (NO in S1000), the process proceeds to S1300. It should be noted that it is only necessary to be able to determine that the vehicle is stopped, rather than to determine strictly at the vehicle speed V = 0.

  In S1100, HV_ECU 320 determines whether or not the charge prohibition flag is in an ON state. If the charge prohibition flag is in the ON state (YES in S1100), the process proceeds to S1600. If not (NO in S1100), the process proceeds to S1200. In S1200, HV_ECU 320 turns on (sets) the charge flag and turns off (resets) the discharge flag. Thereafter, the process proceeds to S1600.

  In S1300, HV_ECU 320 determines whether or not the discharge prohibition flag is in an ON state. If the discharge prohibition flag is in the ON state (YES in S1300), the process proceeds to S1400. If not (NO in S1300), the process proceeds to S1500. In S1400, HV_ECU 320 turns on (sets) the charge flag and turns off (resets) the discharge flag. Thereafter, the process proceeds to S1600. In S1500, HV_ECU 320 turns off (resets) the charge flag and turns on (sets) the discharge flag. Thereafter, the process proceeds to S1600.

In S1600, HV_ECU 320 detects battery temperature TB.
In S1700, HV_ECU 320 determines whether or not battery temperature TB is higher than 0 ° C. If battery temperature TB is higher than 0 ° C. (YES in S1700), the process proceeds to S1800. Otherwise (NO in S1700), this process ends. In S1800, HV_ECU 320 turns off (resets) the charge flag and turns off (resets) the discharge flag.

  When the above-described charging flag is ON, the HV_ECU 320 preferentially uses the motor generator 140 as a generator to charge the traveling battery 220, and when the discharging flag is ON, the HV_ECU 320 has priority. Thus, the motor generator 140 is used as an electric motor so as to be discharged from the traveling battery 220. In addition to this, when the discharge flag is ON, charging control by regenerative braking is prohibited, or the engine 120 is stopped and the vehicle runs only with the motor. As a premise for performing such control, charging is prohibited when the charge prohibition flag is ON, and discharge is prohibited when the discharge prohibition flag is ON.

  An operation of HV_ECU 320 that is the battery control device according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG. In particular, FIG. 4C shows the change in SOC according to the present invention, and FIG. 4E shows the change in SOC according to the prior art.

  When SOC of traveling battery 220 and vehicle speed V are detected (S100) and SOC is less than 50% (YES in S200), the discharge prohibition flag is turned on (set) (S300). If SOC is higher than 52% (YES in S400), the discharge prohibition flag is turned off (reset) (S500). Further, when the SOC is higher than 65% (YES in S600), the charge prohibition flag is turned on (set) (S700). If SOC is less than 63% (YES in S800), the charge prohibition flag is turned off (reset) (S900).

  If the vehicle is running (NO in S1000) and the discharge prohibition flag is ON (set) (YES in S1300), the charge flag is turned ON and the discharge flag is turned OFF (S1400). The motor generator 140 is used as a generator, and a flag state is established in which the traveling battery 220 is charged. As a result, when TB> 0 is not satisfied in S1700 (that is, when the temperature is low and NO in S1700), the state of the flag is not changed (the process of S1800 is not performed), so that motor generator 140 is As a result, the traveling battery 220 is charged, and the temperature of the traveling battery 220 rises.

  If the vehicle is running (NO in S1000) and the discharge prohibition flag is OFF (reset) (NO in S1300), the charge flag is turned OFF, the discharge flag is turned ON, and motor generator 140 is turned ON. Is used as an electric motor, and is discharged preferentially from the traveling battery 220 to lower the SOC (from time t (1) to t (2) in FIG. 4). Thus, by giving priority to discharging while the vehicle is running (by discharging even if the upper limit of the control SOC is not reached), as shown below, the time during which the vehicle can be charged while the vehicle is stopped Can be extended.

  On the other hand, if the vehicle is stopped (YES in S1000) and the charge prohibition flag is not ON (set) (NO in S1100), the charge flag is turned ON and the discharge flag is turned OFF, and the motor generator 140 is used as a generator, and a state where the traveling battery 220 is charged is in a flag state. As a result, when TB> 0 is not satisfied in S1700 (that is, when the temperature is low and NO in S1700), the state of the flag is not changed (the process of S1800 is not performed), so that motor generator 140 is As a result, the traveling battery 220 is charged, and the temperature of the traveling battery 220 rises.

  As shown in FIG. 4 (E), in the conventional technique, the electric discharge is not started until the control SOC upper limit (for example, 65%) is reached during traveling. Therefore, after that, when the vehicle stops, the SOC is higher than that shown in FIG. 4C, and charging starts at time earlier than time t (3) when charging is started while the vehicle is stopped. I was in a state where I couldn't.

  In the present invention, as shown in FIG. 4 (C), the electric discharge was preferentially discharged even if the control SOC upper limit was not reached during traveling. Therefore, when the vehicle stops thereafter, the SOC becomes low as shown in FIG. 4C, and charging can be performed until time t (3) when charging is started while the vehicle is stopped.

  That is, in the present invention, the time from the time t (3) to the time t (4) is shorter than the conventional time. Conventionally, since the discharge was not preferentially performed during traveling, the SOC of the traveling battery 220 does not drop significantly, and the SOC of the traveling battery 220 reaches the control SOC upper limit soon after charging starts. In this case, charging / discharging was not performed immediately.

  In this way, even when the vehicle is stopped, the traveling battery 220 is charged, so the charging current flows through the traveling battery 220 and Joule heat is generated due to internal resistance (in addition to such Joule heat). As a result, heat of reaction due to a chemical reaction inside the battery accompanying charging occurs), and the temperature of the traveling battery 220 can be increased. In particular, while the vehicle is traveling (by executing control such as giving priority to motor traveling or prohibiting regenerative braking), the traveling battery 220 is stopped during a stop that cannot be discharged by reducing the SOC of the traveling battery 220. The SOC of 220 is decreasing. For this reason, the traveling battery 220 can be charged even during a stop that could not be charged / discharged conventionally, and the temperature of the traveling battery can be increased.

  As described above, according to the battery control device of the present embodiment, the fact that the battery temperature does not rise because charging / discharging does not occur during the stop of the vehicle is preferentially discharged during the travel before the stop. In addition, the SOC can be lowered and the battery temperature can be increased by charging the battery using the motor generator as a generator using the engine while the vehicle is stopped.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the structure of the vehicle by which the battery control apparatus which concerns on this Embodiment is mounted. It is a flowchart (the 1) which shows the control structure of the program performed by HV_ECU which is a battery control apparatus which concerns on this Embodiment. It is a flowchart (the 2) which shows the control structure of the program performed by HV_ECU which is a battery control apparatus which concerns on this Embodiment. It is a timing chart which shows operation at the time of being controlled by HV_ECU which is a battery control device concerning this embodiment.

Explanation of symbols

  120 engine, 140 motor generator, 160 drive wheel, 180 speed reducer, 200 power split mechanism, 220 battery for travel, 240 inverter, 242 boost converter, 260 battery ECU, 280 engine ECU, 300 MG_ECU, 320 HV_ECU.

Claims (3)

A control device for a secondary battery mounted on a vehicle comprising an engine that drives the vehicle and a rotating electrical machine that generates electric power by the driving force of the engine,
Temperature detecting means for detecting the temperature of the secondary battery;
Charging state detection means for detecting the charging state of the secondary battery;
Control means for controlling charging and discharging of the secondary battery,
The control means determines a charge prohibition range and a discharge prohibition range in accordance with a charge amount of the secondary battery, respectively, and when the temperature of the secondary battery is higher than a predetermined threshold value, In the control range with the lower limit value of the prohibited range as the upper limit and the upper limit value of the discharge prohibited range as the lower limit, charging and discharging the secondary battery,
When the temperature of the secondary battery is lower than a predetermined threshold value and the amount of charge of the secondary battery is not in the charge prohibited range and the discharge prohibited range, the vehicle is running In order to control the charging so as to give priority to discharging while the vehicle is stopped with the upper limit value of the discharging prohibited range set as the lower limit even if the charging amount has not reached the charging prohibited range . The control apparatus of the secondary battery mounted in the vehicle containing a means.   The said control means is mounted in the vehicle of Claim 1 containing the means for controlling so that the said vehicle drive | works by the electric power discharged from the said secondary battery being fed to the motor for driving | running | working. Secondary battery control device.   The control device for a secondary battery mounted on a vehicle according to claim 2, wherein the electric motor for traveling is the rotating electric machine.

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