JP2013001264A - Vehicle - Google Patents

Abstract

In a vehicle including an engine, a rotating electrical machine connected to the engine, and a battery that exchanges electric power with the rotating electrical machine, a decrease in remaining battery capacity at a low battery temperature is appropriately suppressed.
In a vehicle including an engine, a first MG (motor generator) coupled to the engine, and a battery that exchanges power with the first MG, the ECU is stopped (YES in S10) and When the battery temperature is low (YES in S11), battery discharge allowable power Wout is gradually reduced to 0 kilowatts at a predetermined rate (S12). Thereafter, the ECU transiently lowers the engine rotational speed Ne by transiently lowering the target engine rotational speed Netag by a predetermined amount (S13).
[Selection] Figure 6

Description

  The present invention relates to a vehicle, and more particularly, to a vehicle including an engine, a motor connected to the engine, and a battery that exchanges electric power with the motor.

  JP 2010-158137 A (Patent Document 1) discloses a vehicle including an engine, a motor connected to the engine, and a battery that stores electric power for driving the motor. A technique for limiting the power of the motor so as not to cause overdischarge of the battery is disclosed.

JP 2010-158137 A

  By the way, when the battery temperature is low, it tends to be difficult to recover (increase) the remaining battery capacity. In other words, when the battery temperature is low, the battery charge allowable power is reduced and the battery charge itself is largely limited, so that there is a delay in the recovery of the remaining battery capacity. Furthermore, when the engine power is limited to prevent battery overcharge due to excessive engine power (a state where the motor generated power by the engine power exceeds the allowable power for battery charging), the engine speed becomes transient due to engine power limitation. If an attempt is made to recover the decrease in engine rotation speed with the power of the motor, the battery is discharged, and further delay occurs in the recovery of the remaining battery capacity. However, the above-mentioned Patent Document 1 has no specific mention regarding such a problem and countermeasures.

  The present invention has been made to solve the above-described problems, and an object thereof is to include an engine, a rotating electrical machine connected to the engine, and a battery for transferring power between the rotating electrical machines. In a vehicle, it is to appropriately suppress a decrease in remaining battery capacity when the battery temperature is low.

  A vehicle according to the present invention includes an engine, a rotating electric machine connected to the engine, capable of generating torque for rotating the engine and generating electric power using the power of the engine, and a battery for transferring electric power between the rotating electric machine And a control device for controlling the engine and the rotating electric machine. The control device limits the output of the rotating electrical machine that is consumed to increase the engine speed when the battery temperature is less than the threshold value compared to when the battery temperature is equal to or higher than the threshold value. This suppresses the decrease in the remaining capacity of the battery.

  Preferably, the chargeable power of the battery decreases as the battery temperature decreases. When the temperature of the battery is less than the threshold value, the control device limits the engine output in order to prevent the amount of power generated by the rotating electrical machine from exceeding the allowable charging power due to excessive engine output, and limits the engine output. This limits the output of the rotating electrical machine that is consumed to recover the reduced engine speed.

  Preferably, the control device reduces the target rotational speed of the engine in response to limiting the output of the rotating electrical machine.

  Preferably, the control device limits the output of the rotating electrical machine by reducing the discharge allowable power of the battery or the output command value of the rotating electrical machine.

  Preferably, the control device limits the output of the rotating electrical machine when the user requests a saving operation in addition to the case where the temperature of the battery is lower than the threshold value.

  Preferably, the control device limits the output of the rotating electrical machine when the remaining battery capacity is less than a predetermined value in addition to when the battery temperature is less than the threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, in the vehicle provided with the engine, the rotary electric machine connected with the engine, and the battery which exchanges electric power between rotary electric machines, the fall of the battery remaining capacity at the time of a battery low temperature is suppressed appropriately. be able to.

1 is an overall block diagram of a vehicle. It is a figure (the 1) which shows an alignment chart at the time of a stop. It is a figure (the 2) which shows an alignment chart at the time of a stop. It is a functional block diagram of ECU. It is a figure which shows the time change of engine power and battery power. It is a flowchart which shows the process sequence of ECU.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an overall block diagram of a vehicle 1 according to an embodiment of the present invention. Referring to FIG. 1, this vehicle 1 includes an engine 10, a first MG (Motor Generator) 20, a second MG 30, a power split device 40, a speed reducer 50, drive wheels 51, and a PCU (Power Control Unit). ) 60, a battery 70, and an ECU (Electronic Control Unit) 200.

  Engine 10, first MG 20 and second MG 30 are connected via power split device 40. The vehicle 1 travels with driving force output from at least one of the engine 10 and the second MG 30. The power generated by the engine 10 is divided into two paths by the power split device 40. That is, one is a path that is transmitted to the drive wheels 51 via the speed reducer 50 and the other is a path that is transmitted to the first MG 20. The vehicle according to the present invention is not limited to a hybrid vehicle of the type including an engine and two MGs as shown in FIG. For example, a hybrid vehicle having an engine and one MG may be used.

  The engine 10 is controlled by a control signal S1 from the ECU 200. First MG 20 and second MG 30 are AC rotating electrical machines, for example, three-phase AC synchronous motors. First MG 20 generates power using the power of engine 10 divided by power split device 40. Second MG 30 generates a driving force using at least one of the electric power stored in battery 70 and the electric power generated by first MG 20. Then, the driving force of the second MG 30 is transmitted to the driving wheels 51 via the speed reducer 50. When the vehicle is braked, the second MG 30 is driven by the drive wheels 51 via the speed reducer 50, and the second MG 30 operates as a generator. Thereby, 2nd MG30 functions also as a regenerative brake which converts kinetic energy of vehicles into electric power. The regenerative power generated by second MG 30 is stored in battery 70.

  Power split device 40 includes a planetary gear including a sun gear, a pinion gear, a carrier, and a ring gear. The pinion gear engages with the sun gear and the ring gear. The carrier supports the pinion gear so as to be capable of rotating, and is connected to the crankshaft of the engine 10. The sun gear is connected to the rotation shaft of the first MG 20. The ring gear is connected to the rotation shaft of second MG 30 and speed reducer 50. As described above, the engine 10, the first MG 20, and the second MG 30 are connected via the power split device 40 including the planetary gear, so that the engine rotational speed Ne, the first MG rotational speed Ng, and the second MG rotational speed Nm are collinear. In the figure, the relationship is a straight line.

  2 and 3 are diagrams showing collinear diagrams when the vehicle is stopped. As described above, the engine rotational speed Ne, the first MG rotational speed Ng, and the second MG rotational speed Nm are in a relationship of being connected by a straight line in the alignment chart. The second MG rotation speed Nm corresponds to the vehicle speed V. When the vehicle stops (when the vehicle speed V is 0), the second MG rotational speed Nm is 0, and the engine rotational speed Ne is feedback controlled to the target engine rotational speed Netag using the torque of the engine 10 or the torque of the first MG 20.

  FIG. 2 shows torque of first MG 20 (hereinafter referred to as “first MG torque Tg”) and torque transmitted from first MG 20 to engine 10 (hereinafter referred to as “first MG transmission torque Tge”). As shown in FIG. 2, when the first MG torque Tg is made positive by discharging from the battery 70, the first MG transmission torque Tge (Tge> 0) in the positive direction acts on the engine 10, so the engine speed Ne is Can be increased. On the other hand, if the first MG 20 generates power and the first MG torque Tg is a negative torque, the first MG transmission torque Tge (Tge <0) in the negative direction acts on the engine 10, so that the engine speed Ne can be reduced. .

  FIG. 3 shows torque of engine 10 (hereinafter referred to as “engine torque Te”) and torque transmitted from engine 10 to first MG 20 (hereinafter referred to as “engine transmission torque Teg”). As shown in FIG. 3, when the engine torque Te is increased in the positive direction, the first MG rotation speed Ng is increased because the engine transmission torque Teg in the positive direction acts on the first MG 20. At this time, the first MG 20 generates power.

  In any case, when first MG 20 functions as a motor, discharging from battery 70 to first MG 20 is performed. When first MG 20 functions as a generator, power generated by first MG 20 is charged in battery 70.

  Returning to FIG. 1, the PCU 60 is controlled by a control signal S <b> 2 from the ECU 200. PCU 60 converts the DC power stored in battery 70 into AC power that can drive first MG 20 and second MG 30 and outputs the converted AC power to first MG 20 and / or second MG 30. Thereby, first MG 20 and / or second MG 30 are driven by the electric power stored in battery 70. Further, the PCU 60 converts the AC power generated by the first MG 20 and / or the second MG 30 into DC power that can charge the battery 70 and outputs the DC power to the battery 70. Thereby, battery 70 is charged with the electric power generated by first MG 20 and / or second MG 30.

  The battery 70 is a direct current power source that stores electric power for driving the first MG 20 and / or the second MG 30, and includes, for example, a secondary battery such as nickel metal hydride or lithium ion. The voltage of the battery 70 is about 200V, for example.

  The actual discharge power and charge power of the battery 70 are controlled so as not to exceed the battery discharge allowable power Wout and the battery charge allowable power Win, respectively, in order to protect the battery 70. The battery discharge allowable power Wout and the battery charge allowable power Win are set according to the battery remaining capacity SOC and the battery temperature. When the battery temperature is low, both the battery discharge allowable power Wout and the battery charge allowable power Win are reduced to small values. In particular, when the battery temperature is extremely low, for example, less than minus 10 ° C., the battery charging allowable power Win may be a minute value of about several kilowatts.

  Further, the vehicle 1 includes an eco switch 11 and a monitoring unit 71. The eco switch 11 is a switch for the user to input an operation requesting a saving operation. When the user presses the eco switch 11, the eco switch 11 transmits to the ECU 200 a signal D1 indicating that the user is requesting a saving operation.

  The monitoring unit 71 monitors the state of the battery 70 (specifically, battery current, battery voltage, and battery temperature), and transmits a signal D2 indicating the monitoring result to the ECU 200.

  The ECU 200 includes a CPU (Central Processing Unit) and a memory (not shown), and is configured to execute predetermined arithmetic processing based on information stored in the memory and information from each sensor.

  ECU 200 sets the above-described battery discharge allowable power Wout and battery charge allowable power Win according to the remaining battery capacity SOC and battery temperature, and sets the actual discharge power and charge power of battery 70 to battery discharge allowable power Wout and battery charge, respectively. Control is performed so as not to exceed the allowable power Win.

  The ECU 200 prevents the generated power of the first MG 20 using engine power from exceeding the battery charge allowable power Win (when the battery 70 is overcharged) when the battery temperature is low (when the battery charge allowable power Win is reduced to a small value). The engine power upper limit value corresponding to the battery charge allowable power Win is set, and the actual engine power is controlled so as not to exceed the engine power upper limit value.

  The ECU 200 sets the target engine speed Nettag according to the accelerator operation amount and performs feedback control of the engine 10 and the first MG 20 so that the engine speed Ne approaches the target engine speed Nettag. At this time, when the engine power is limited to be less than the above-described engine power upper limit value, the engine speed Ne is made closer to the target engine speed Netag using the first MG torque Tg (see FIG. 2).

  In the vehicle 1 having the above configuration, the battery remaining capacity SOC tends not to be recovered (increased) when the battery temperature is low. That is, when the battery temperature is low, the battery charging allowable power Win is set to a small value and the charging of the battery 70 is largely restricted, so that there is a delay in the recovery of the remaining battery capacity SOC. Further, the engine power upper limit value is also set to a small value in response to the battery charge allowable power Win being set to a small value. Therefore, there is a concern that the engine power is transiently reduced and the engine speed Ne is transiently reduced below the target engine speed Netag, but the first MG torque Tg is increased to recover the engine speed Ne that has fallen. If it does, it will discharge from the battery 70 and the further delay will arise in recovery | restoration of battery remaining capacity SOC.

  Therefore, in the vehicle 1 according to the present embodiment, when the battery temperature is low, the remaining battery capacity SOC is reduced by limiting the first MG torque Tg (discharge amount of the battery 70) consumed to recover the drop in the engine speed Ne. Try not to reduce as much as possible. This is the most characteristic point of the present invention.

  FIG. 4 is a functional block diagram of ECU 200 when limiting discharge of battery 70. Each functional block shown in FIG. 4 may be realized by hardware or software.

  ECU 200 includes a first determination unit 210, a second determination unit 220, a Tg restriction unit 230, and a Ne reduction unit 240.

  The first determination unit 210 determines whether or not the vehicle is stopped. This determination is a process for determining whether or not the behavior of the vehicle 1 does not change abruptly even if the discharge of the battery 70 is limited by a Tg limiting unit 230 described later. This determination can be made based on, for example, whether the vehicle speed V is substantially zero or whether the shift range is the P (parking) range.

  The second determination unit 220 determines whether or not the battery temperature is lower than the threshold temperature. This determination is a process for determining whether or not the battery charge allowable power Win is limited to a value smaller than a predetermined value.

  Tg limiting unit 230 limits the output of first MG torque Tg by limiting the discharge of battery 70 when the vehicle is stopped and the battery temperature is lower than the threshold temperature. That is, when the battery temperature is lower than the threshold temperature, the engine power is limited to less than the engine power upper limit value in accordance with the decrease in the battery charge allowable power Win, and therefore the engine speed Ne is set to the target engine speed Nettag only with the engine power. However, in the present embodiment, this shortage of power is allowed, and intentionally limiting the shortage of power with the output of the first MG torque Tg (discharge of the battery 70) is intentionally limited. . Thereby, the fall of battery remaining capacity SOC is suppressed and a fuel consumption can be improved.

  Hereinafter, a case will be described as an example in which the discharge limitation of the battery 70 (the output limitation of the first MG torque Tg) is realized by reducing the battery discharge allowable power Wout.

  When the vehicle is stopped and the battery temperature is lower than the threshold temperature, Tg restriction unit 230 gradually reduces battery discharge allowable power Wout at a predetermined rate (predetermined change rate) to 0 kilowatts. Thereby, as described above, it is possible to suppress a decrease in the battery remaining capacity SOC. In addition, since the battery discharge allowable power Wout is gradually decreased at a predetermined rate rather than rapidly, the influence on the vehicle behavior can be minimized.

  The Ne lowering unit 240 transiently lowers the engine rotational speed Ne by transiently lowering the target engine rotational speed Netag by a predetermined amount according to the decrease in the battery discharge allowable power Wout by the Tg limiting unit 230. As a result, the power (inertia consumption power) necessary to maintain the engine rotational speed Ne at the target engine rotational speed Netag is lowered, and the energy balance is adjusted for power shortage.

  FIG. 5 is a diagram showing temporal changes in engine power and battery power when the battery temperature is low.

  When the battery temperature is low, the battery charge allowable power Win is reduced to a small value. Further, in order to prevent battery overcharge due to excessive engine power, the engine power is limited to less than the engine power upper limit value. Accordingly, when the engine power reaches the engine power upper limit value, the engine power falls transiently (see the hatched portion A).

  Conventionally, the battery discharge allowable power Wout has not been reduced to 0 kilowatt (see the alternate long and short dash line). Therefore, discharging of the battery 70 (output of the first MG torque Tg) was allowed in accordance with the drop in engine power (see the hatched portion B). The discharge of the battery 70 has been a factor for reducing the battery remaining capacity SOC.

  In contrast, in the present embodiment, when it is determined at time t1 that the vehicle is stopped and the battery temperature is lower than the threshold temperature, battery discharge allowable power Wout is gradually reduced at a predetermined rate, and time t2 Is reduced to 0 kilowatts. Therefore, the battery 70 is not discharged (the output of the first MG torque Tg) even when the engine power falls transiently. Thereby, the fall of battery remaining capacity SOC is suppressed and a fuel consumption improves. At this time, as described above, the engine rotational speed Ne is transiently reduced in accordance with the drop in engine power. As described above, in the present embodiment, the engine rotational speed Ne is transiently reduced even when the engine power transitions transiently, thereby suppressing the discharge of the battery 70 and preventing the remaining battery capacity SOC from decreasing. Prioritize that.

  FIG. 6 is a flowchart showing a processing procedure of the ECU 200 for realizing the above-described functions. The flowchart shown in FIG. 6 is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as “S”) 10, ECU 200 determines whether or not the vehicle is stopped. If the vehicle is not stopped (NO in S10), the process is terminated.

  When the vehicle is stopped (YES in S10), ECU 200 moves the process to S11, and determines whether or not the battery is at a low temperature (whether or not the battery temperature is lower than the threshold temperature). If the battery temperature is not low (NO in S11), the process is terminated.

  When the battery temperature is low (YES in S11), ECU 200 moves the process to S12 and limits the discharge of battery 70. That is, the battery discharge allowable power Wout is gradually reduced to 0 kilowatts at a predetermined rate. Thereafter, in S13, the ECU 200 transiently lowers the engine rotational speed Ne by transiently reducing the target engine rotational speed Netag by a predetermined amount.

  As described above, in the vehicle 1 according to the present embodiment, when the battery temperature is low, the output of the first MG 20 (discharge power of the battery 70) consumed to recover the drop in the engine rotation speed Ne is limited. The remaining capacity SOC is not reduced as much as possible. Therefore, it is possible to appropriately suppress a decrease in the remaining battery capacity SOC when the battery temperature is low.

In addition, this Embodiment can also be changed as follows, for example.
In the present embodiment, as a method of limiting battery discharge, a method of reducing battery discharge allowable power Wout is used, but the method of limiting battery discharge is not limited to this. For example, the discharge of the battery 70 may be limited by reducing the command value of the first MG torque Tg. Further, during the feedback control of the engine rotation speed Ne using the first MG torque Tg, the discharge start timing of the battery 70 is delayed by lowering the engine rotation speed threshold for determining the output start of the first MG torque Tg. May be.

  In the present embodiment, the battery discharge is limited to “stopping” and “when the battery is cold”. However, the conditions for limiting the battery discharge can be changed. For example, instead of or in addition to the condition “when the battery is cold” (the condition that is YES in S11 in FIG. 6), “in the eco mode (when the user requests the saving operation by pressing the eco switch 11) It may be set as a condition. By limiting the discharge of the battery during the eco mode, it is possible to improve the fuel consumption according to the user's request. Further, in addition to the conditions of “stopped” and “when the battery is cold”, a condition that “the remaining battery capacity SOC is less than a predetermined value” may be added. As a result, when the battery remaining capacity SOC has a margin, it is possible to compensate for the drop in engine power with the first MG torque Tg without limiting the discharge of the battery.

  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.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 10 Engine, 11 Eco switch, 40 Power split device, 50 Reduction gear, 51 Drive wheel, 60 PCU, 70 Battery, 71 Monitoring unit, 200 ECU, 210 1st determination part, 220 2nd determination part, 230 Tg Limiting part, 240 Ne lowering part.

Claims (6)

Engine,
A rotating electrical machine coupled to the engine and capable of generating torque for rotating the engine and generating power using the power of the engine;
A battery that exchanges power with the rotating electrical machine;
A control device for controlling the engine and the rotating electrical machine,
When the temperature of the battery is lower than a threshold value, the control device consumes the rotating electrical machine to increase the rotational speed of the engine as compared with the case where the temperature of the battery is equal to or higher than the threshold value. The vehicle which suppresses the fall of the remaining capacity of the said battery by restrict | limiting the output of this. The allowable charging power of the battery decreases as the temperature of the battery decreases,
When the temperature of the battery is lower than the threshold, the control device limits the engine output in order to prevent the power generation amount of the rotating electrical machine from exceeding the allowable charging power due to excessive output of the engine. 2. The vehicle according to claim 1, wherein the vehicle is configured to limit the output of the rotating electrical machine that is consumed to recover the engine speed reduced by the engine output limit.   The vehicle according to claim 2, wherein the control device decreases a target rotational speed of the engine in response to limiting the output of the rotating electrical machine.   The vehicle according to claim 2, wherein the control device limits the output of the rotating electrical machine by reducing an allowable discharge power of the battery or an output command value of the rotating electrical machine.   The vehicle according to claim 1, wherein the control device limits the output of the rotating electrical machine when a user requests a saving operation in addition to a case where the temperature of the battery is lower than the threshold value. .   The said control apparatus restrict | limits the output of the said rotary electric machine when the remaining capacity of the said battery is less than predetermined value in addition to the case where the temperature of the said battery is less than the said threshold value. Vehicle.

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