JP2010115035A - Battery protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery protection device capable of preventing overvoltage of a battery by reliably consuming excessive power even if the excessive power is generated in regeneration. <P>SOLUTION: The battery protection device includes: a battery; an electric load; and a control means. The battery charges regenerative power to be supplied. The electric load consumes part of the regenerative power supplied to the battery to prevent overvoltage of the battery. The control means controls the regenerative power supplied to the battery and the electric load. The control means sets a target upper limit output value of the regenerative power at a value smaller by a predetermined value than the power consumption capability of the electric load. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for protecting a battery from overvoltage.

  2. Description of the Related Art Conventionally, a technology that uses regenerative power that has not been able to fully charge a battery in a hybrid vehicle or the like is known. For example, Patent Document 1 describes a technique for heating a secondary battery using surplus current due to regeneration. Patent Document 2 describes a technique for supplying surplus power to an auxiliary load that raises the temperature of a storage battery.

Japanese Patent Laid-Open No. 11-150885 JP 2008-117565 A

  On the other hand, depending on the running state of the vehicle, surplus power different from the regenerative power that is intentionally supplied to the battery or the auxiliary load described above may be supplied to the battery or the like. In this case, if the regenerative power is controlled using the power that can be consumed by the battery or the auxiliary load as the target upper limit value, it may not be possible to consume the surplus power.

  The present invention has been made to solve the above-described problems, and even when surplus power is generated during regeneration, the surplus power is surely consumed and battery overvoltage is prevented. An object of the present invention is to provide a possible battery protection device.

  In one aspect of the present invention, a battery protection device includes a battery that charges regenerative power, an electric load that consumes regenerative power, and a control unit that controls regenerative power supplied to the battery and the electric load. The control means sets a target upper limit output value of regenerative power smaller by a predetermined value from the power consumption capability of the electric load.

  The above battery protection device is suitably applied to a hybrid vehicle or the like. The battery protection device includes a battery, an electrical load, and control means. A battery is a secondary battery, for example, and charges the supplied regenerative electric power. The electric load consumes part of the regenerative power supplied to the battery, thereby preventing overvoltage of the battery. The control means is, for example, an ECU (Electronic Control Unit), and controls regenerative power supplied to the battery and the electric load. The control means sets the target upper limit output value of the regenerative power by a predetermined value smaller than the power consumption capability of the electric load. The predetermined value is set to, for example, an assumed upper limit value of surplus power.

  Generally, when the battery is at a low temperature, the charging performance (chargeable power) of the battery is low. Further, surplus power may be supplied to the battery and the electric load depending on the traveling state of the vehicle. However, even in such a case, the control means sets the target upper limit output value to a value that is smaller by a predetermined value than the power consumption capacity of the electric load, thereby preventing overvoltage of the battery based on excessive power supply. Can do.

  In another aspect of the battery protection device, the control unit sets the predetermined value based on the likelihood of overvoltage of the battery. In this aspect, the control means sets the predetermined value to a large value in a situation where the battery is likely to cause an overvoltage to prevent the battery from being overvoltage. On the other hand, the control means sets the predetermined value to a small value in a situation where the battery is unlikely to cause overvoltage, and consumes a large amount of regenerative power by the battery or the electric load. That is, in this aspect, the battery temperature adjusting device can prevent the regenerative power from being unnecessarily limited while preventing the battery from overvoltage.

  In another aspect of the battery protection device, the predetermined value is set based on a state of the battery. The overvoltage of the battery is likely to occur when the battery is in a high voltage state or when the state of charge of the battery is close to saturation. That is, the likelihood of battery overvoltage varies depending on the battery condition. Therefore, the control means can appropriately set the predetermined value according to this aspect.

  In another aspect of the battery protection device described above, the battery protection device is mounted on a vehicle, and the regenerative power control unit sets the predetermined value based on a running state of the vehicle. The amount of surplus power and the likelihood of occurrence vary depending on the running state of the vehicle. Therefore, the battery protection measure can appropriately set a predetermined value also by this aspect.

  In another aspect of the battery protection device, the electrical load is a heater that heats the battery. Thereby, the battery protection apparatus can utilize the regenerative power consumed by the electric load for heating the battery. Therefore, the battery protection device can promote warm-up of the battery and improve the charging performance and discharging performance of the battery.

  In another aspect of the battery protection device described above, the control means determines a target upper limit output value of regenerative power from the power consumption capability of the electric load when the charge allowable power of the battery is smaller than the power consumption capability. When the charging allowable power of the battery is equal to or higher than the power consumption capacity, the target upper limit output value of power is set smaller than the charging allowable power by the predetermined value. When the battery is sufficiently warmed up and the allowable charging power is equal to or greater than the power consumption capacity of the electrical load, the battery protection device can reduce the regenerative power consumption unnecessarily by adjusting the target upper limit output value to the power consumption capacity of the electrical load. There is a possibility. Therefore, according to this aspect, the battery protection device can consume regenerative power more effectively.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Schematic configuration]
FIG. 1 is a schematic diagram showing a configuration of a battery protection device 100 according to each embodiment of the present invention. The battery protection device 100 is preferably applied to a hybrid vehicle, an electric vehicle, and the like (hereinafter referred to as “vehicle”). Battery protection device 100 includes a battery 1, a surplus power consumption unit 2, and a load unit 3. The battery protection device 100 transmits a driving force generated by electric power supplied from the battery 1 to the load unit 3 to wheels (not shown). Thereby, the vehicle carrying the battery protection device 100 travels. Further, the battery protection device 100 generates electric power from the kinetic energy by the load unit 3 and collects it in the battery 1 during regeneration.

  The load unit 3 performs driving and regeneration based on the control of the ECU 10. Load unit 3 includes a converter 31, inverters 32 and 33, and motor generators MG1 and MG2.

  The battery 1 performs discharging and charging. The battery 1 is connected to the surplus power consumption unit 2. The battery 1 corresponds to, for example, a secondary battery configured to be chargeable / dischargeable, such as a nickel metal hydride battery or a lithium ion battery. Hereinafter, the upper limit value of the power that can be charged by the battery 1 is referred to as “charge allowable power Win”, and the lower limit value of the power that can be discharged by the battery 1 is referred to as “discharge allowable power Wout”. Battery 1 is charged by regenerative power supplied from converter 31 during regeneration.

  The surplus power consumption unit 2 consumes the regenerative power supplied from the converter 31. And the surplus power consumption part 2 heats the battery 1 with the heat generated by consuming the regenerative power. The surplus power consumption unit 2 is controlled by a control signal (switching signal) S1 transmitted from the ECU 10. The surplus power consumption unit 2 is an example of an electric load in the present invention.

  The converter 31 is installed between the battery 1 and the surplus power consumption unit 2 and the inverters 32 and 33, and exchanges power between them. Specifically, converter 31 boosts the discharge power from battery 1 to a predetermined voltage and supplies it as drive power to inverters 32 and 33, while reducing the regenerative power from motor generators MG1 and MG2 to a predetermined voltage. Then, the battery 1 or the surplus power consumption unit 2 is supplied.

  Inverters 32 and 33 are connected in parallel to converter 31 and exchange power with converter 31. In other words, inverters 32 and 33 convert driving power (DC power) received from converter 31 into AC power and supply it to motor generators MG1 and MG2, respectively, while AC power generated by motor generators MG1 and MG2 is converted to DC power. Converted and supplied to the converter 31 as regenerative power.

  Motor generators MG1 and MG2 receive AC power supplied from inverters 32 and 33, respectively, to generate rotational driving force, and generate regenerative power by receiving external rotational driving force. As an example, motor generators MG1 and MG2 may be three-phase AC rotating electric machines including a rotor in which permanent magnets are embedded. Motor generators MG1 and MG2 are each connected to power transmission mechanism 36, and transmit the generated driving force to wheels (not shown) by driving shaft 38.

  When battery protection device 100 is applied to a hybrid vehicle, motor generators MG1 and MG2 are also connected to an engine (not shown) via power transmission mechanism 36 or drive shaft 38. Then, the ECU 10 performs control so that the driving force generated by the engine and the driving force generated by the motor generators MG1 and MG2 have an optimal ratio. In this case, motor generator MG1 functions exclusively as a generator, and motor generator MG2 functions exclusively as an electric motor.

  The voltage detection unit 14 is connected between the power lines connecting the battery 1 and the surplus power consumption unit 2, detects the voltage value Vb applied to the battery 1, and outputs the detection result to the ECU 10.

  The temperature detection unit 12 is disposed in the vicinity of the battery cells constituting the battery 1, detects the battery temperature Tb that is the internal temperature of the battery 1, and outputs the detection result to the ECU 10. Note that the temperature detection unit 12 is configured to output a representative value by an averaging process or the like based on detection results of a plurality of detection elements arranged in association with a plurality of battery cells constituting the battery 1. Also good.

  Smoothing capacitor C <b> 1 is connected between power lines connecting converter 31 and inverters 32 and 33, and reduces fluctuation components included in drive power output from converter 31 and regenerative power output from inverters 32 and 33.

  The ECU (Electronic Control Unit) 10 has a CPU, ROM, RAM, A / D converter, input / output interface, and the like (not shown), and controls driving of the motor generators MG1 and MG2 based on detection signals from various sensors. Do. More specifically, ECU 10 generates control signals S3 and S4 to control inverters 32 and 33 so that the generated torque and rotational speed of motor generators MG1 and MG2 become the torque target value and the rotational speed target value, respectively. To do. Further, as will be described later, the ECU 10 controls the regenerative power based on the allowable charging power Win, the upper limit value of power that can be consumed by the surplus power consumption unit 2 (hereinafter referred to as “power consumption capacity Wr”), and the like. To do. Therefore, ECU10 is an example of the control means in this invention.

  FIG. 2 is an example of a circuit diagram of the battery protection device 100. As shown in FIG. 2, the inverters 32 and 33 are configured by a bridge circuit including switching elements for three phases, and generate three-phase AC power based on control signals S3 and S4 from the ECU 10.

  Converter 31 is configured by a step-up / down chopper circuit. Converter 31 includes transistors TR1 and TR2 that are switching elements, diodes D1 and D2, an inductor L, and a smoothing capacitor C2.

  In FIG. 2, the battery protection device 100 includes system main relays 19x and 19y (not shown in FIG. 1). The system main relays 19x and 19y relay or interrupt the current flowing to the battery 1. In a vehicle collision or the like, the system main relays 19x and 19y completely cut off the high voltage in order to ensure the safety of the passenger.

  Surplus power consumption unit 2 includes a resistor R, a diode D3, and a transistor TR3. The resistor R and the diode D3 are connected in parallel between the power line connected to the positive electrode side of the battery 1 and the collector of the transistor TR3. The resistor R is, for example, a heater adjacent to the battery 1 and heats the battery 1 with heat generated by the resistor R. Diode D3 allows current to flow from the collector side of transistor TR3 to the power line side connected to the positive electrode of battery 1. The transistor TR3 is, for example, an IGBT (Insulated Gate Bipolar Transistor), and is a switching element controlled based on a switching signal S1 transmitted from the ECU 10. The transistor TR3 has a collector connected to the resistor R and the diode D3, and an emitter connected to the negative electrode side of the battery 1. Hereinafter, the state in which the ECU 10 transmits the switching signal S1 to the transistor TR3 and the current flows through the resistor R is expressed as “the surplus power consumption unit is on”, and the switching signal S1 is not transmitted from the ECU 10 and the current flows through the resistor R. The state of not flowing is expressed as “the surplus power consumption unit is off”.

  Next, functions realized by the surplus power consumption unit 2 and the converter 31 based on the control signals S1 and S2 transmitted by the ECU 10 will be described with reference to FIG.

  ECU 10 causes converter 31 to perform a step-up operation or a step-down operation based on switching signal S2a and switching signal S2b included in control signal S2. Specifically, the ECU 10 controls on / off of the transistor TR1 by the switching signal S2a, and controls on / off of the transistor TR2 by the switching signal S2b. During the boosting operation, the ECU 10 maintains the transistor TR1 in the off state and turns on / off the transistor TR2 at a predetermined duty ratio. Thereby, due to the electromagnetic energy accumulated in inductor L, the average voltage of the DC power that converter 31 supplies to inverters 32 and 33 is boosted according to the duty ratio. Further, during the step-down operation, the ECU 10 turns on / off the transistor TR1 with a predetermined duty ratio and maintains the transistor TR2 in an off state. As a result, the average voltage of the DC power supplied from converter 31 to battery 1 or surplus power consumption unit 2 is stepped down according to the duty ratio.

  Moreover, ECU10 adjusts the electric power consumed in the surplus power consumption part 2 based on switching signal S1. The power consumption capability Wr of the surplus power consumption unit 2 is a value obtained by dividing the square of the voltage value Vb by the resistance value of the resistor R. Further, the power consumed by the surplus power consumption unit 2 is the product of the duty ratio of the switching signal S1 and the power consumption capability Wr. Therefore, the ECU 10 adjusts the power actually consumed by the surplus power consumption unit 2 by the duty control of the switching signal S1. As an example, the ECU 10 monitors the voltage value Vb detected from the voltage detection unit 14 and turns on the surplus power consumption unit 2 for a predetermined time when the voltage value Vb reaches a predetermined allowable voltage of the battery 1 or the vicinity thereof. To do. Thereby, ECU10 reduces the voltage of the battery 1 by making the surplus power consumption part 2 consume electric power, and prevents that the battery 1 becomes an overvoltage more than an allowable voltage.

  In addition, the structure of the above-mentioned battery protection apparatus 100 is an example, and the structure to which the present invention can be applied is not necessarily limited thereto. For example, there may be one motor generator. FIG. 3 shows a configuration example of a battery protection device 100a including one motor generator. As shown in FIG. 3, battery protection device 100a includes a motor generator MG. Motor generator MG operates as an electric motor by the electric power of battery 1 when driven, and operates as a generator during braking. Even in this case, the ECU 10 controls the on / off of the surplus power consumption unit 2 by the control signal S1, and controls the regenerative power supplied by the converter 31 by the control signal S2, as will be described later. Prevent overvoltage etc.

[Control in the first embodiment]
Next, regenerative control performed by the ECU 10 in the first embodiment will be described. In the first embodiment, the ECU 10 sets the upper limit value of the regenerative power supplied by the converter 31 to the power consumption capability Wr of the surplus power consumption unit 2 even when the battery 1 is at a low temperature and the charge allowable power Win is small. . Thereby, the ECU 10 effectively uses the regenerative power while preventing the overvoltage of the battery 1. Hereinafter, of the regenerative power generated by the motor generators MG1 and MG2, the regenerative power supplied from the converter 31 to the battery 1 and the surplus power consumption unit 2 based on the control of the ECU 10 is referred to as “regenerative output”.

  First, regenerative output control in the first embodiment will be described. The ECU 10 sets the target upper limit value (hereinafter referred to as “target upper limit output value Wmax”) for controlling the regenerative output to a value that is larger of the power consumption capacity Wr or the charge allowable power Win. This will be described with reference to FIG.

  FIG. 4 is an example of a graph showing the relationship between the allowable charging power Win, the allowable discharging power Wout, and the target upper limit output value Wmax in the first embodiment. In FIG. 4, in the power on the vertical axis, the positive direction indicates the discharge power, and the negative direction indicates the charge power. As shown in FIG. 4, the absolute values of the allowable charging power Win and the allowable discharging power Wout increase as the battery temperature Tb increases. When the battery temperature Tb is equal to or lower than the predetermined temperature Tb1, the charge allowable power Win is smaller than the power consumption capability Wr. Therefore, when the battery temperature Tb is equal to or lower than the temperature Tb1, the ECU 10 sets the target upper limit output value Wmax of the regenerative output to the power consumption capability Wr. Then, the regenerative output exceeding the charge allowable power Win is supplied to the resistor R of the surplus power consumption unit 2 based on the control signal S1 of the ECU 10 and consumed by the resistor R. At this time, the regenerative output exceeding the allowable charging power Win is equal to or less than the power consumption capacity Wr even when the battery temperature Tb is low and the allowable charging power Win is small. Therefore, the resistor R can reliably consume the supplied power. Therefore, the battery protection device 100 can prevent the occurrence of an overvoltage of the battery 1 due to the excessive supply of power to the battery 1. Furthermore, by causing the resistor R to function as a heater adjacent to the battery 1, the battery protection device 100 can heat the battery 1 with heat generated due to the power consumption of the resistor R. As a result, the battery 1 increases the allowable charging power Win and the allowable discharge power Wout as the temperature rises, so that the battery protection device 100 can improve the fuel consumption as a result and can effectively utilize the regenerative power.

  Next, a specific example of the regenerative output during traveling in the first embodiment will be shown. FIG. 5 shows a graph of the time variation of the regenerative output when the battery 1 is at a low temperature. A graph 91 indicated by a broken line is a graph of a change in regenerative output when the target upper limit output value Wmax is always set to the charge allowable power Win (hereinafter referred to as “comparative example”). A graph 92 indicated by a solid line is a graph representing the regenerative output when the target upper limit output value Wmax is set to the larger one of the power consumption capacity Wr and the charge allowable power Win, that is, the present embodiment. Further, the allowable charging power Win is indicated by a broken line. The absolute value of the chargeable power Win gradually increases due to the increase in the battery temperature Tb over time.

  As shown in FIG. 5, regenerative power is generated by braking control in the periods A to D. In the comparative example, the regenerative output remains below the allowable charging power Win in any period (see graph 91). On the other hand, the regenerative output indicated by the graph 92 exceeds the allowable charging power Win with the power consumption capability Wr as the upper limit in any of the periods A to D. Even in this case, the regenerative output in excess of the allowable charging power Win becomes equal to or less than the power consumption capability Wr and is consumed by the surplus power consumption unit 2. As described above, the battery protection device 100 according to the present embodiment consumes more regenerative power in a range in which the supply of chargeable power to the battery 1 does not become excessive as compared with the comparative example.

(Processing flow)
Next, a processing procedure in the first embodiment will be described. FIG. 6 is a flowchart illustrating an example of control performed by the ECU 10 in the first embodiment. The process shown in FIG. 6 is repeatedly executed by the ECU 10 when regeneration is performed or at predetermined intervals.

  First, the ECU 10 acquires the charge allowable power Win and the power consumption capability Wr (step S1). For example, the ECU 10 estimates the allowable charging power Win by referring to a map as shown in FIG. 4 stored in advance in the memory based on the battery temperature Tb detected from the temperature detection unit 12. In addition, the ECU 10 acquires the power consumption capability Wr by holding the power consumption capability Wr calculated in advance based on the resistance value of the resistor R in a memory in advance.

  Next, the ECU 10 determines whether or not the allowable charging power Win is smaller than the power consumption capability Wr (step S2).

  When the allowable charging power Win is greater than the power consumption capacity Wr (step S2; Yes), the ECU 10 sets the target upper limit output value Wmax to the allowable charging power Win (step S3). In other words, when the allowable charging power Win is larger than the power consumption capacity Wr, the ECU 10 can sufficiently consume the regenerative power and the overvoltage of the battery 1 does not occur even if the allowable charging power Win is set to the target upper limit output value Wmax. Judge.

  On the other hand, when the power consumption capability Wr is smaller than the charge allowable power Win (step S2; No), the ECU 10 sets the target upper limit output value Wmax to the power consumption capability Wr (step S4). That is, in this case, since the allowable charging power Win is small, the ECU 10 determines that the regenerative power cannot be sufficiently consumed only by charging the battery 1, and sets the upper limit of the regenerative output to the power consumption capacity Wr. Thereby, ECU10 can consume the regenerative power in the surplus power consumption part 2, and can prevent the overvoltage of the battery 1. FIG.

  Next, the ECU 10 controls the regenerative output based on the target upper limit output value Wmax determined in step S3 or step S4 (step S5). Specifically, ECU 10 controls converter 31 so as not to exceed target upper limit output value Wmax. Further, the ECU 10 performs duty control of the switching signal S1 while monitoring the voltage value Vb and the like so that the battery 1 does not become overvoltage.

(Modification)
In the above description, the ECU 10 sets the target upper limit output value Wmax to the power consumption capability Wr or the charge allowable power Win. Instead, the ECU 10 sets the target upper limit output value Wmax to the sum of the charge allowable power Win and the power consumption capability Wr. May be set. In this case, by doing in this way, the battery protection device 100 can make maximum use of the regenerative power generated by the motor generators MG1 and MG2 within a range in which no excessive power supply to the battery 1 occurs.

  As another example, the ECU 10 may fix the target upper limit output value Wmax to the power consumption capability Wr. That is, the ECU 10 may set the power consumption capability Wr as the target upper limit output value Wmax regardless of the charge allowable power Win. Thus, control of ECU10 is simplified by making target upper limit output value Wmax into the power consumption capability Wr which is a fixed value. Further, by designing the resistor R so that the power consumption capability Wr becomes a relatively large value, the ECU 10 can fully utilize the regenerative power even in this case.

[Second Embodiment]
In the first embodiment, the ECU 10 sets the target upper limit output value Wmax of the regenerative output to the larger one of the power consumption capacity Wr and the charge allowable power Win, and controls the regenerative output based on the target upper limit output value Wmax. On the other hand, when the regenerative power is large, such as when the wheel grips after slipping while the vehicle is running, surplus power different from the regenerative output controlled by the ECU 10, that is, the ECU 10 has not been fully controlled (understood). Sudden power (hereinafter referred to as “surplus power We”) may be supplied to the battery 1 and the surplus power consumption unit 2. In this case, there is a concern that the battery 1 and the surplus power consumption unit 2 are supplied with power that is equal to or higher than the target upper limit output value Wmax due to the surplus power We and an overvoltage of the battery 1 is generated. Therefore, in the second embodiment, the ECU 10 lowers the target upper limit output value Wmax of the regenerative output by a predetermined value from the target upper limit output value Wmax used in the first embodiment. Thereby, the ECU 10 prevents overvoltage of the battery 1.

  FIG. 7 is an example of a graph showing the relationship between the allowable charging power Win, the allowable discharging power Wout, and the target upper limit output value Wmax in the second embodiment. As shown in FIG. 7, the charge allowable power Win takes a value that is smaller by a constant ΔP than the power consumption capability Wr at the temperature Tb2. The target upper limit output value Wmax is set to a value that is smaller than the power consumption capability Wr by a constant ΔP when the temperature is equal to or lower than the temperature Tb2. Here, the constant “ΔP” is a value smaller than the power consumption capability Wr, and is set in advance by experiments or the like to a value equal to or greater than the surplus power We. For example, the constant ΔP is set to the upper limit value of the surplus power We that can be generated. Therefore, the target upper limit output value Wmax is set to a value obtained by dividing the power consumption capability Wr by the constant ΔP at the temperature Tb2 or lower.

Thus, when the battery temperature Tb is equal to or lower than the temperature Tb2, the ECU 10 reduces the target upper limit output value Wmax by a constant ΔP from the power consumption capability Wr, that is,
Wmax = Wr−ΔP
By setting to, the overvoltage of the battery 1 due to the surplus power We is prevented. That is, when the target upper limit output value Wmax is set to a value obtained by subtracting the constant ΔP from the power consumption capacity Wr and the constant ΔP is set to be equal to or greater than the surplus power We, the maximum value of the regenerative output including the surplus power We is the power It becomes below the consumption capacity Wr. Therefore, the battery protection device 100 can appropriately consume the regenerative output including the surplus power We even when the surplus power We is generated.

(Processing flow)
Next, a processing procedure in the second embodiment will be described with reference to FIG. The processes in steps S101 to S105 according to the second embodiment are the same as those in the first embodiment except for steps S103 and S104.

  The ECU 10 acquires the allowable charging power Win and the power consumption capability Wr (step S101) and compares them (step S102). When the allowable charging power Win is greater than the power consumption capacity Wr (step S102; Yes), the ECU 10 sets the target upper limit output value Wmax to a value obtained by subtracting the constant ΔP from the allowable charging power Win (step S103). The constant ΔP is set to a value larger than the expected surplus electric power We by a prior experiment or the like, and is held in the memory of the ECU 10.

  On the other hand, when the allowable charging power Win is smaller than the power consumption capability Wr (step S102; No), the ECU 10 sets the target upper limit output value Wmax to a value obtained by subtracting the constant ΔP from the power consumption capability Wr (step S104). Then, the ECU 10 controls the regenerative output based on the target upper limit output value Wmax (step S105). As described above, even if the surplus power We is generated, the ECU 10 can prevent the overvoltage of the battery 1 by setting the constant ΔP to a value larger than the surplus power We.

  The modification in the first embodiment can also be applied to the second embodiment. That is, the ECU 10 may set the target upper limit output value Wmax to a value that is smaller by a constant ΔP than the sum of the charge allowable power Win and the power consumption capability Wr. Instead, the target upper limit output value Wmax may always be set to a value smaller than the power consumption capacity Wr by a constant ΔP regardless of the charge allowable power Win.

[Third Embodiment]
In the second embodiment, the ECU 10 sets the target upper limit output Wmax small by a constant ΔP previously stored in a memory or the like in consideration of the surplus power We. On the other hand, in the third embodiment, the ECU 10 sets the variable “ΔPh” corresponding to the constant ΔP to an appropriate value during traveling, and sets the target upper limit output value Wmax to be smaller by the variable ΔPh. Thereby, the ECU 10 increases the regenerative output while preventing the overvoltage of the battery 1.

  Hereinafter, a method for determining the variable ΔPh will be described. The ECU 10 determines the variable ΔPh using the likelihood of overvoltage of the battery 1 as an index. That is, when it is determined that overvoltage is likely to occur, the ECU 10 sets the target upper limit output value Wmax to be small in order to prevent overvoltage. On the other hand, when it is determined that overvoltage is unlikely to occur, the ECU 10 sets the target upper limit output value Wmax to be large in order to prioritize the consumption of regenerative power.

  Further, the likelihood of overvoltage of the battery 1 correlates with the state of the battery 1 or the running state of the vehicle. Here, the state of the battery 1 is, for example, a state of charge (SOC) of the battery 1, a voltage of the battery 1, a degree of deterioration of the battery 1, a load of the battery 1 in a past fixed time, and the like. Generally, when the battery SOC is close to saturation, the battery 1 has a small allowable voltage and is likely to be overvoltage. Moreover, even when the voltage of the battery 1 is high before the regeneration control, overvoltage is likely to occur. Furthermore, even when the battery 1 is deteriorated, the battery 1 has a small allowable voltage and is likely to be overvoltage. Further, when the charging / discharging load of the battery 1 is increased over a certain period of time in the past, the battery 1 tends to be overvoltage due to an error in control of the ECU 10 or the like.

  In addition, overvoltage of the battery 1 is likely to occur when the vehicle is in a traveling state where surplus power We is generated. Here, the traveling state of the vehicle in which the surplus power We is generated is, for example, when the wheel provided in the vehicle grips after slipping, when the accelerator that changes engine inertia greatly is turned on or off, and when the accelerator and brake This applies when both are enabled. In such a running state of the vehicle, during braking, a relatively large wheel power is transmitted to the motor generator MG1 or the motor generator MG2 via the power transmission mechanism 36 and the drive shaft 38, and a large regenerative electric power is generated. As a result, power that is equal to or higher than the target upper limit output value Wmax, that is, surplus power We is supplied to the battery 1 and the surplus power consumption unit 2, and overvoltage of the battery 1 is likely to occur.

  Therefore, the ECU 10 acquires the state of the battery 1 and the traveling state of the vehicle from various sensors at predetermined intervals or when regenerative control is performed, and sets the variable ΔPh. For example, the ECU 10 selects a plurality of elements for determining the state of the battery 1 and the traveling state of the vehicle described above, creates a map indicating the relationship between these elements and the amount of surplus power in advance by experiment or the like, and stores it in the memory. Keep it. Then, the ECU 10 acquires each selected element from the sensor when regenerative control is performed, and sets the variable ΔPh based on the map described above.

  As described above, by determining the variable ΔPh based on the likelihood of overvoltage of the battery 1, the ECU 10 sets the variable ΔPh to be small in a situation where the overvoltage of the battery 1 is unlikely to occur, so that more regenerative power is supplied to the battery. 1 or surplus power consumption unit 2 consumes. Therefore, the ECU 10 can effectively use the regenerative power, and as a result, can improve fuel efficiency. Further, the ECU 10 sets the variable ΔPh to a large value and sets the target upper limit output value Wmax to a small value when the overvoltage of the battery 1 is likely to occur. Thereby, the ECU 10 can suppress the overvoltage of the battery 1.

(Processing flow)
Next, an example of a processing procedure in the third embodiment will be described with reference to FIG. This process is executed by the ECU 10 at predetermined intervals or when regenerative control is performed.

  First, the ECU 10 obtains charge allowable power Win, power consumption capability Wr, battery 1 state, and vehicle running state from various sensors (step S201). For example, the ECU 10 obtains the voltage value Vb from the voltage detection unit 14 to grasp the voltage of the battery 1 and grasps the accelerator and brake depression amount based on detection signals from an accelerator sensor and a brake position sensor (not shown). Thus, the traveling state of the vehicle is grasped.

  Next, the ECU 10 calculates a variable ΔPh based on the acquired state of the battery 1 and the traveling state of the vehicle (step S202). For example, the ECU 10 sets the variable ΔPh by referring to a map of the state of the battery 1 and the running state of the vehicle and surplus power that is created in advance through experiments or the like.

  Next, the ECU 10 compares the allowable charging power Win with the power consumption capability Wr (step S203). If the allowable charging power Win is greater than the power consumption capability Wr (step S203; Yes), the target upper limit output value Wmax is charged. A value obtained by subtracting the variable ΔPh from the allowable power Win is set (step S204). On the other hand, when the charge allowable power Win is smaller than the power consumption capability Wr (step S203; No), the ECU 10 sets the target upper limit output value Wmax to a value obtained by subtracting the variable ΔPh from the power consumption capability Wr (step S205).

  Then, the ECU 10 controls the regenerative output based on the set target upper limit output value Wmax (step S206).

  Note that the modification in the first embodiment can also be applied to the third embodiment. That is, the ECU 10 may set the target upper limit output value Wmax to a value that is smaller by the variable ΔPh than the sum of the allowable charging power Win and the power consumption capability Wr. Instead, the target upper limit output value Wmax may always be set to a value smaller than the power consumption capability Wr by the variable ΔPh regardless of the allowable charging power Win.

It is an example of the figure which shows the typical top view of a battery protection apparatus. It is an example of the circuit diagram of a battery protection apparatus. It is an example of the circuit diagram of a battery protection apparatus provided with one motor generator. It is an example of the graph of charge allowable power with respect to battery temperature, discharge allowable power, and target upper limit output value in 1st Embodiment. It is an example of the graph of the change of the regenerative output accompanying a time change. It is a flowchart showing an example of the process sequence which concerns on 1st Embodiment. It is an example of the graph of charge allowable power with respect to battery temperature, discharge allowable power, and target upper limit output value in 2nd Embodiment. It is a flowchart showing an example of the process sequence which concerns on 2nd Embodiment. It is a flowchart showing an example of the process sequence which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Surplus power consumption part 3 Load part 10 ECU
DESCRIPTION OF SYMBOLS 12 Temperature detection part 14 Voltage detection part 31 Converter 32, 33 Inverter 36 Power transmission mechanism 38 Drive shaft MG1, MG2 Motor generator 100 Battery protection apparatus

Claims (6)

A battery that charges regenerative power;
An electrical load that consumes regenerative power;
Control means for controlling regenerative power supplied to the battery and the electric load,
The battery protection device according to claim 1, wherein the control means sets a target upper limit output value of regenerative power by a predetermined value smaller than a power consumption capability of the electric load.   The battery protection device according to claim 1, wherein the control unit sets the predetermined value based on the likelihood of overvoltage of the battery.   The battery protection device according to claim 2, wherein the control unit sets the predetermined value based on a state of the battery. Mounted on the vehicle,
The battery protection device according to claim 2, wherein the control unit sets the predetermined value based on a traveling state of the vehicle.   The battery protection device according to any one of claims 1 to 4, wherein the electrical load is a heater that heats the battery.   When the allowable charging power of the battery is smaller than the power consumption capacity, the control means sets a target upper limit output value of regenerative power smaller by the predetermined value than the power consumption capacity of the electric load, and charges the battery The battery protection device according to any one of claims 1 to 5, wherein when the allowable power is equal to or greater than the power consumption capacity, a target upper limit output value of power is set smaller than the charge allowable power by the predetermined value.

Images