JP2019081430A - Hybrid system of vehicle - Google Patents

Abstract

To solve the problem that power regenerated by a motor generator cannot be efficiently used as charging power of a battery.SOLUTION: An electronic control device calculates a request regenerative electric amount RGreq required for a motor generator according to an operation state of a vehicle. The electronic control device calculates a prediction duration Tp of power regeneration in the motor generator. When the prediction duration TP is lower than specified time Tx (NO, in step S16) and the request regenerative power amount RGreq is lower than a specific power amount, the electronic control device controls a DC/DC converter so that a high-voltage battery is charged preferentially to a low-voltage battery, otherwise, controls the DC/DC converter so that the low-voltage battery is charged preferentially to the high-voltage battery.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hybrid system of a vehicle.

  The hybrid system of Patent Document 1 includes a main battery for supplying electric power to a motor generator for traveling, and a sub-battery for supplying electric power to an electric pump for generating a negative pressure of a brake mechanism. Further, the motor generator in the hybrid system of Patent Document 1 functions as a generator at the time of deceleration when the accelerator pedal of the vehicle is not depressed. When the charge capacity of the sub-battery is equal to or less than a predetermined reference value, the motor generator supplies power to the sub-battery to preferentially charge the sub-battery.

Japanese Patent Application Publication No. 06-339203

  In the hybrid system provided with two batteries like patent document 1, a lithium ion battery may be employ | adopted as a main battery, and a lead storage battery may be employ | adopted as a subbattery. And generally, the lead acid battery has a larger charging resistance per voltage than a lithium ion battery. Thus, in the configuration in which the charging resistance of the sub-battery is higher, if the sub-battery is preferentially charged like the hybrid system of Patent Document 1, power is consumed by the charging resistance of the sub-battery. . Therefore, there is a possibility that the power regenerated by the motor generator can not be efficiently used as charging power of the battery.

  In order to solve the above problems, the present invention relates to a motor generator drivingly connected to an engine, a high voltage battery for supplying power to the motor generator, and a DC for stepping down and outputting the power from the high voltage battery and the motor generator. / DC converter, a low voltage battery which has a larger charging resistance per voltage than the high voltage battery and is supplied with power from the DC / DC converter, and a control unit which controls an output voltage of the DC / DC converter The control unit calculates the required regenerative electric energy required for the motor generator according to the driving state of the vehicle, calculates the predicted duration of power regeneration in the motor generator, and continues the prediction The time is equal to or longer than a predetermined time, or the required regenerative power amount is predetermined. Control the DC / DC converter such that the low voltage battery is charged more preferentially than the high voltage battery, and the estimated duration is less than the specified time, and If the required regenerative power amount is less than the specified power amount, the DC / DC converter is controlled such that the high voltage battery is charged more preferentially than the low voltage battery.

  In the above configuration, under the situation where the predicted continuation time is equal to or longer than the specified time or under the situation where the required regenerative power is equal to or greater than the predetermined power, the power that can charge each battery is relatively large. Therefore, an excessively large charging current may act on the high voltage battery, which causes deterioration of the high voltage battery. In the above configuration, when there is a possibility that an excessively large charging current may act on the high voltage battery, the low voltage battery is preferentially charged, and the load on the high voltage battery can be reduced accordingly.

  On the other hand, in the above configuration, under the situation where the predicted continuation time is less than the specified time and the required regenerative power is less than the specified power, the power that can charge each battery is not so large. In the above configuration, under such a condition, the high voltage battery having a relatively low charging resistance is preferentially charged, thereby suppressing the power loss due to the charging resistance of the low voltage battery and efficiently using the regenerative power. I am trying.

The schematic block diagram of a hybrid system. The graph which shows notionally the regenerative energy of the low voltage battery and the high voltage battery at the time of using the 1st map. The graph which shows notionally the regenerated electric energy of the low voltage battery and the high voltage battery at the time of using the 2nd map. The flowchart which shows the control processing of the DC / DC converter. The flowchart which shows the control processing of the DC / DC converter.

Hereinafter, embodiments of the present invention will be described. First, the schematic configuration of the hybrid system will be described according to FIG.
As shown in FIG. 1, the hybrid system includes an engine 10 and a motor generator 20 as drive sources. The crankshaft of the engine 10 is drivingly connected to drive wheels via a transmission or the like (not shown). Further, a crankshaft of the engine 10 is drivingly connected to the first pulley 11. The transmission belt 12 is wound around the first pulley 11. Although not shown, the crankshaft of the engine 10 is also drivingly connected to a pump for generating hydraulic pressure, a compressor of an air conditioner, or the like through a belt, a pulley, a chain, and the like.

  Motor generator 20 is a so-called three-phase alternating current motor. The output shaft of the motor generator 20 is drivingly connected to the second pulley 13. The transmission belt 12 is wound around the second pulley 13. That is, the motor generator 20 is drivingly connected to the engine 10 via the second pulley 13, the transmission belt 12, and the first pulley 11. When the motor generator 20 functions as an electric motor, it applies a rotational torque to the second pulley 13, and the rotational torque is input to the crankshaft of the engine 10 via the transmission belt 12 and the first pulley 11. That is, the motor generator 20 assists the drive of the engine 10. On the other hand, when the motor generator 20 functions as a generator, the rotational torque of the crankshaft of the engine 10 is transmitted to the output shaft of the motor generator 20 via the first pulley 11, the transmission belt 12 and the second pulley 13. It is input. Then, the motor generator 20 generates electric power according to the rotation of the output shaft.

  A high voltage battery 22 is connected to the motor generator 20 via an inverter 21. The inverter 21 is a so-called bidirectional inverter, which converts the AC voltage generated by the motor generator 20 into a DC voltage and outputs the DC voltage to the high voltage battery 22, and converts the DC voltage output from the high voltage battery 22 into an AC voltage to convert the motor generator Output to 20. In FIG. 1, although the inverter 21 is depicted as being separate from the motor generator 20, the inverter 21 may be incorporated in the housing of the motor generator 20.

  The high voltage battery 22 is a lithium ion battery. The high voltage battery 22 supplies power to the motor generator 20 when the motor generator 20 functions as an electric motor. Further, when the motor generator 20 functions as a generator, the high voltage battery 22 is charged by receiving the supply of power from the motor generator 20.

  A DC / DC converter 23 is connected to the motor generator 20 via an inverter 21. The DC / DC converter 23 is also connected to the high voltage battery 22. The DC / DC converter 23 steps down the DC voltage output from the inverter 21 or the high voltage battery 22 to 12 V to 15 V and outputs it. A low voltage battery 24 is connected to the DC / DC converter 23.

  The low voltage battery 24 is a 12 V lead storage battery whose voltage is lower than that of the high voltage battery 22, and the charging resistance per voltage is larger than that of the high voltage battery 22 which is a lithium ion battery. The low voltage battery 24 outputs a DC voltage of 12 V when the DC / DC converter 23 is not driven or when the output voltage of the DC / DC converter 23 is 12 V. The low voltage battery 24 is charged by being supplied with power from the DC / DC converter 23 when the output voltage of the DC / DC converter 23 is larger than the open circuit voltage (OCV) of the low voltage battery 24.

  Various auxiliary devices 25 are connected to the DC / DC converter 23 and the low voltage battery 24. Examples of the auxiliary device 25 include, for example, lights such as a headlight of a vehicle, a direction indication light, and a room light, and vehicle interior equipment such as a car navigation device and a speaker. The accessory 25 receives power supply from the low voltage battery 24 when the DC / DC converter 23 is not driven. When the output voltage of the DC / DC converter 23 is larger than the open circuit voltage (OCV) of the low voltage battery 24, the auxiliary device 25 receives the supply of power from the DC / DC converter 23.

  The hybrid system includes an electronic control unit 30 as a control unit for controlling the motor generator 20 and the DC / DC converter 23 described above. The electronic control unit 30 includes an operation unit that executes various programs (applications), a non-volatile storage unit in which programs and the like are stored, and a volatile memory and the like in which data is temporarily stored when the programs are executed. Computer.

  A signal indicating output information IC of the DC / DC converter 23 is input to the electronic control unit 30 from the DC / DC converter 23. The output information IC of the DC / DC converter 23 is an output voltage value and an output current value of the DC / DC converter 23. A signal indicating the state information IH of the high voltage battery 22 is input to the electronic control unit 30 from the high voltage battery 22. The state information IH of the high voltage battery 22 is an output voltage value, an output current value, and a temperature of the high voltage battery 22. A signal indicating the state information IL of the low voltage battery 24 is input to the electronic control unit 30 from the low voltage battery 24. The state information IL of the low voltage battery 24 is an output voltage value, an output current value, and a temperature of the low voltage battery 24. The electronic control unit 30 receives, from each accessory 25, a signal indicating the status information IA of the accessory 25. The state information IA of each accessory 25 is an input voltage value and an input current value to each accessory 25.

  The electronic control unit 30 also receives signals from various sensors and the like mounted on the vehicle. Specifically, a signal indicating the vehicle speed SP of the vehicle is input to the electronic control unit 30 from the vehicle speed sensor 31. Further, the electronic control unit 30 receives a signal indicating the depression amount BR of the brake pedal from the brake sensor 32 (brake stroke sensor) and a signal indicating the depression amount AC of the accelerator pedal from the accelerator sensor 33 (acceleration stroke sensor). Ru.

  Further, a signal from the gyro sensor 34 is input to the electronic control unit 30. The gyro sensor 34 outputs the inclination of the vehicle with respect to the horizontal direction to the electronic control unit 30 as posture information GY. A signal from the millimeter wave radar 35 is input to the electronic control unit 30. The millimeter wave radar 35 is mounted on the front of a vehicle and emits radio waves (millimeter waves) having a wavelength of 1 mm to 10 mm toward the front of the vehicle. Then, the millimeter wave radar 35 detects a radio wave reflected by another vehicle ahead, and calculates an inter-vehicle distance LD between the own vehicle and the other vehicle located in front of the own vehicle. The millimeter wave radar outputs a signal indicating the calculated inter-vehicle distance LD to the electronic control unit 30.

  Electronic control device 30 calculates operation signal MSmg for controlling motor generator 20 based on various signals input, and outputs the operation signal MSmg to motor generator 20. Further, the electronic control unit 30 calculates an operation signal MSc for controlling the DC / DC converter 23 based on various signals inputted, and outputs the operation signal MSc to the DC / DC converter 23.

  The storage unit of the electronic control unit 30 stores a first map and a second map which are referred to when the operation signal MSc to the DC / DC converter 23 is calculated. The relationship between the required regenerative electric energy RGreq required for the motor generator 20 and the regenerative electric energy RGL to the low-voltage battery 24 is shown in the first map and the second map.

  Specifically, in the first map, as shown in FIG. 2, the regenerated electric energy RGL of the low-voltage battery 24 is equal to the electric energy X1 required for the required regenerative electric energy RGreq equal to the electric energy PC used for the accessory 25. It is zero. From the time when the required regenerative power amount RGreq exceeds the power amount X1 to the power amount X2 obtained by adding the upper limit regenerative amount RGLmax of the low-voltage battery 24 to the power consumption PC of the auxiliary device 25, the required regenerative power amount RGreq increases The regenerative electric energy RGL to the low voltage battery 24 increases from zero toward the upper limit regenerative amount RGLmax. Then, after the required regenerative power amount RGreq exceeds the power amount X2, the regenerative power amount RGL of the low voltage battery 24 is constant at the upper limit regenerative amount RGLmax. The upper limit regeneration amount RGLmax of the low voltage battery 24 is the amount of regenerative power when the DC / DC converter 23 outputs the maximum voltage.

  Further, in the second map, as shown in FIG. 3, until the required regenerative electric energy RGreq reaches the electric energy X4 determined as a value larger than the electric energy X1 equal to the electric energy PC used by the accessory 25, low voltage The regenerative electric energy RGL of the battery 24 is zero. Then, after the required regenerative power amount RGreq exceeds the power amount X4, the regenerative power amount RGL of the low voltage battery 24 is constant at the upper limit regenerative amount RGLmax. Electric power amount X4 is determined such that a value obtained by subtracting electric power consumption PC of auxiliary device 25 from required regenerative electric power amount RGreq does not exceed upper limit regenerative amount RGHmax of high-voltage battery 22. The upper limit regeneration amount RGHmax of the high voltage battery 22 is determined as an amount of power that does not impose an excessive burden on the high voltage battery 22 when the high voltage battery 22 is charged, and is determined in advance by tests and simulations.

  Next, control processing of the DC / DC converter 23 and the motor generator 20 by the electronic control unit 30 will be described according to FIGS. 4 and 5. The control processing of the DC / DC converter 23 and the motor generator 20 described below has predetermined control when the depression amount AC of the accelerator pedal detected by the accelerator sensor 33 is zero (when the accelerator is off). It is repeatedly executed at intervals. Further, control processing of DC / DC converter 23 and motor generator 20 is performed when it is determined that both batteries can be charged based on status information IH of high voltage battery 22 and status information IL of low voltage battery 24.

As shown in FIG. 4, when the control process of the DC / DC converter 23 and the motor generator 20 is started, the electronic control unit 30 first executes the process of step S11.
In step S11, electronic control unit 30 calculates required regenerative electric energy RGreq required for motor generator 20. Specifically, the electronic control unit 30 realizes the deceleration of the vehicle intended by the driver of the vehicle based on the depression amount BR of the brake pedal detected by the brake sensor 32, the vehicle speed SP detected by the vehicle speed sensor 31, and the like. The regenerative electric energy required for the motor generator 20 to be calculated is calculated as the required regenerative electric energy RGreq. After the required regenerative electric energy RGreq is calculated, the process of the electronic control unit 30 proceeds to step S12.

  In step S12, the electronic control unit 30 calculates the power consumption PC of the accessory 25 based on the state information IA of each accessory 25. Although the power consumption PC of the auxiliary device 25 changes depending on the driving state of the vehicle and the driver's operation, it is illustrated as a constant value in FIGS. 2 and 3. After the power consumption PC of the auxiliary device 25 is calculated, the process of the electronic control unit 30 proceeds to step S13.

  In step S13, electronic control unit 30 determines whether requested regenerative power amount RGreq calculated in step S11 is larger than the power consumption amount PC of auxiliary device 25 calculated in step S12. If requested regenerative power amount RGreq is less than or equal to the power consumption PC of auxiliary device 25 (NO in step S13), the process of electronic control device 30 proceeds to step S14.

  In step S14, the electronic control unit 30 sets the regenerated electric energy RGL of the low voltage battery 24 to zero. Then, the electronic control unit 30 controls the output voltage of the DC / DC converter 23 to substantially the same voltage as the output voltage of the low voltage battery 24 so that the regenerated electric energy RGL of the low voltage battery 24 becomes zero. Further, the electronic control unit 30 sets the target power generation amount of the motor generator 20 to the required regenerative power amount RGreq, and outputs an operation signal MSmg according to the request to the motor generator 20. In this case, since the output voltage of the DC / DC converter 23 is not higher than the output voltage of the low voltage battery 24, the low voltage battery 24 is hardly charged. Further, since almost the entire required regenerative energy RGreq is used for the auxiliary device 25, the high voltage battery 22 is also hardly charged. Thereafter, the series of processes of the electronic control unit 30 end, and after a predetermined control interval, the process of step S11 is performed again.

  On the other hand, when it is determined in step S13 that requested regenerative energy RGreq is larger than the power consumption PC of auxiliary device 25 (YES in step S13), the process of electronic control device 30 shifts to step S15. In step S <b> 15, electronic control unit 30 calculates a predicted value of a duration of power regeneration in motor generator 20 as predicted regeneration time Tp. Specifically, the electronic control unit 30 calculates the predicted regeneration time Tp longer as the vehicle speed SP detected by the vehicle speed sensor 31 is larger. Further, the electronic control unit 30 determines whether the vehicle is traveling on a down slope or is traveling on an up slope based on the posture information GY detected by the gyro sensor 34. Then, the electronic control unit 30 calculates the predicted regeneration time Tp to be longer as the descending slope becomes stronger, and calculates the predicted regeneration time Tp to be shorter as the rising slope becomes stronger. Further, the electronic control unit 30 calculates the predicted regeneration time Tp longer as the inter-vehicle distance LD detected by the millimeter wave radar 35 becomes longer. Thereafter, the process of the electronic control unit 30 proceeds to step S16.

  In step S16, the electronic control unit 30 determines whether the predicted regeneration time Tp is equal to or longer than the specified time Tx. The prescribed time Tx is a time in which excessive deterioration or the like does not occur in the high voltage battery 22 even when the regenerative power generated by the motor generator 20 is continuously supplied only to the high voltage battery 22, according to the characteristics of the high voltage battery 22. It is determined. The specified time Tx can be obtained in advance by performing tests and simulations. If the predicted regeneration time Tp is equal to or longer than the specified time Tx (YES in step S16), the process of the electronic control device 30 proceeds to step S17.

  In step S17, the electronic control unit 30 calculates the regenerated electric energy RGL of the low voltage battery 24 based on the first map. As described above, when based on the first map, as shown in FIG. 2, the regenerative power RGL of the low voltage battery 24 is from the time when the required regenerative power RGreq exceeds the power X1 until the power X2 is reached, It is calculated so as to increase from zero toward the upper limit regeneration amount RGLmax. Further, when the required regenerative power amount RGreq exceeds the power amount X2, the regenerative power amount RGL of the low voltage battery 24 is calculated to be the upper limit regenerative amount RGLmax. Thereafter, the process of the electronic control unit 30 proceeds to step S19.

  On the other hand, when it is determined in step S16 that the predicted regeneration time Tp is less than the specified time Tx (NO in step S16), the process of the electronic control device 30 shifts to step S18. In step S18, the electronic control unit 30 calculates the regenerated electric energy RGL of the low voltage battery 24 based on the second map. As described above, when based on the second map, as shown in FIG. 3, the regenerative electric energy RGL of the low voltage battery 24 is calculated to be zero until the required regenerative electric energy RGreq reaches the electric energy X4. Further, when the required regenerative power amount RGreq exceeds the power amount X4, the regenerative power amount RGL of the low voltage battery 24 is calculated as the upper limit regenerative amount RGLmax. Thereafter, the process of the electronic control unit 30 proceeds to step S19.

  In step S19, the electronic control unit 30 calculates a target voltage of the DC / DC converter 23 in accordance with the regenerative electric energy RGL of the low voltage battery 24 calculated in step S17 or step S18. Specifically, when the regenerated electric energy RGL of the low voltage battery 24 is zero, the electronic control unit 30 calculates the target voltage of the DC / DC converter 23 as substantially the same voltage as the output voltage of the low voltage battery 24. Then, the electronic control unit 30 calculates the target voltage of the DC / DC converter 23 as a larger value as the regenerative power RGL increases, and when the regenerative power RGL is the upper limit regenerative amount RGLmax, the maximum output of the DC / DC converter 23 The target voltage is calculated (15 V in this embodiment). After calculating the target voltage of the DC / DC converter 23, the electronic control unit 30 outputs an operation signal MSc according to the target voltage to the DC / DC converter 23. Then, the process of the electronic control unit 30 proceeds to step S20.

  As shown in FIG. 5, in step S20, the electronic control unit 30 controls the current DC based on the output information IC (voltage value and current value) of the DC / DC converter 23 output from the DC / DC converter 23. The output electric energy Pout of the / DC converter 23 is calculated. Thereafter, the process of the electronic control unit 30 proceeds to step S21.

  In step S21, the electronic control unit 30 determines whether the required regenerative power amount RGreq is larger than the output power amount Pout calculated in step S20. When the required regenerative electric energy RGreq is equal to or less than the output voltage Pout (NO in step S21), the process of the electronic control device 30 shifts to step S22.

  In step S22, electronic control unit 30 sets the target electric energy of motor generator 20 to required regenerative electric energy RGreq, and outputs an operation signal MSmg according to the request to motor generator 20. In this case, a part of the power generated by motor generator 20 is used by accessory 25. Then, the surplus power not used in the auxiliary device 25 is supplied to the low voltage battery 24 and the low voltage battery 24 is charged. It is to be noted that almost all of the electric power generated by motor generator 20 is supplied to low voltage battery 24 and auxiliary device 25 via DC / DC converter 23, so high voltage battery 22 is hardly charged. Thereafter, the series of processes of the electronic control unit 30 end, and after a predetermined control interval, the process of step S11 is performed again.

  On the other hand, when it is determined in step S21 that the required regenerative power amount RGreq is larger than the output power amount Pout calculated in step S20 (YES in step S21), the process of the electronic control device 30 shifts to step S23.

  In step S23, the electronic control unit 30 subtracts the output electric energy Pout of the DC / DC converter 23 calculated in step S20 from the required regenerative electric energy RGreq from the predetermined upper limit regeneration amount for the high voltage battery 22. It is determined whether or not RGHmax or more. If the above determination is affirmative (YES in step S23), the process of the electronic control device 30 proceeds to step S24.

  In step S24, the electronic control unit 30 sets an upper limit regeneration amount RGHmax as the regeneration power amount RGH of the high voltage battery 22. Thereafter, the process of the electronic control unit 30 proceeds to step S26.

  On the other hand, in step S23, when it is determined that the value obtained by subtracting output power amount Pout of DC / DC converter 23 from required regenerative power amount RGreq is less than the upper limit regenerative amount RGHmax for high voltage battery 22 (in step S23) (NO), the process of the electronic control unit 30 proceeds to step S25.

  In step S25, the electronic control unit 30 sets a value obtained by subtracting the output power amount Pout of the DC / DC converter 23 from the required regenerative power amount RGreq as the regenerative power amount RGH of the high voltage battery 22. Thereafter, the process of the electronic control unit 30 proceeds to step S26.

  In step S26, electronic control unit 30 sets, as a target power generation amount of motor generator 20, a value obtained by adding regenerative electric energy RGH of high-voltage battery 22 to output electric energy Pout of DC / DC converter 23. Thereafter, the series of processes of the electronic control unit 30 end, and after a predetermined control interval, the process of step S11 is performed again.

The operation and effects of the above embodiment will be described.
In the above embodiment, as shown in FIG. 2 and FIG. 3, the motor generator MG generates electric power until the required regenerative electric energy RGreq of the motor generator 20 reaches the electric energy X1 equal to the electric power consumption PC of the auxiliary device 25. Regenerative power is supplied to the accessory 25 and consumed by the accessory 25. Therefore, the amount of power supplied from low voltage battery 24 to accessory 25 can be reduced.

  After the required regenerative electric energy RGreq of motor generator 20 exceeds electric energy X1, the mode of supplying power to high voltage battery 22 and low voltage battery 24 is switched according to the length of predicted regeneration time Tp. Under the situation where the predicted regeneration time Tp is equal to or longer than the specified time Tx, the amount of power that can be supplied to each battery is correspondingly large. Therefore, if all the amount of electric power is supplied to high voltage battery 22, an excessively large voltage may act on high voltage battery 22, which causes deterioration of high voltage battery 22 or the like. In the above embodiment, under the condition that the predicted regeneration time Tp is equal to or longer than the specified time Tx, as shown in FIG. 2, the regenerative power generated by the motor generator 20 is preferentially supplied to the low voltage battery 24. 24 is charged. Therefore, the application of an excessively large voltage to the high voltage battery 22 is suppressed, and the load on the high voltage battery 22 can be reduced.

  On the other hand, under the situation where the predicted regeneration time Tp is less than the specified time Tx, the amount of power that can be supplied to each battery is not so large. Therefore, when power is supplied to the low voltage battery 24 with high charging resistance under such a condition, a large amount of power is consumed in the low voltage battery 24, and the regenerative power generated by the motor generator 20 can not be efficiently used. In the above embodiment, under the situation where the predicted regeneration time Tp is equal to or longer than the specified time Tx, as shown in FIG. 3, the regenerative power generated by the motor generator 20 is preferentially supplied to the high voltage battery 22, 22 is charged. Therefore, the power loss due to the charging resistance of the low voltage battery 24 can be suppressed, and the regenerative power can be efficiently used.

  Even under the condition that predicted regeneration time Tp is less than prescribed time Tx, the regeneration generated by motor generator 20 is performed when required regenerative electric energy RGreq of motor generator 20 exceeds a prescribed electric energy X4. Power is preferentially supplied to the low voltage battery 24 to charge the low voltage battery 24. Therefore, it is possible to suppress the occurrence of deterioration or the like on the high voltage battery 22 due to an excessively large voltage acting on the high voltage battery 22, and to supply the low voltage battery 24 with power that can not be received by the high voltage battery 22.

  Furthermore, in the above embodiment, even if the value obtained by subtracting the output power amount Pout of the DC / DC converter 23 from the required regenerative power amount RGreq exceeds the upper limit regenerative amount RGHmax of the high voltage battery 22, the regenerative power amount of the high voltage battery 22 RGH becomes the upper limit regeneration amount RGHmax. That is, as shown in FIG. 2 and FIG. 3, the electric power obtained by adding the required electric energy PC of the auxiliary device 25, the upper regenerative amount RGLmax of the low voltage battery 24, and the upper regenerative amount RGHmax of the high voltage battery 22 to the required regenerative electric energy RGreq. When it is larger than the amount X3, the target charge amount of the motor generator 20 is limited to the electric power amount X3. Therefore, an excessive load on the high voltage battery 22 is suppressed.

The above embodiment can be modified as in the following example. In addition, it is also possible to apply a plurality of modified examples in combination as needed.
The output voltages of the high voltage battery 22 and the low voltage battery 24 do not matter. If the output voltage of the low voltage battery 24 is lower than the output voltage of the high voltage battery 22, the control process of the DC / DC converter 23 and the motor generator 20 of the above embodiment can be applied.

  The types of the high voltage battery 22 and the low voltage battery 24 are not limited to the examples of the above embodiment. For example, as the high voltage battery 22 or the low voltage battery 24, a nickel hydrogen battery or a NAS battery may be adopted other than the lithium ion battery or the lead storage battery. Whatever storage battery is adopted, if the charging resistance of the low voltage battery 24 is higher than the charging resistance of the high voltage battery 22, control processing of the DC / DC converter 23 and the motor generator 20 of the above embodiment is performed. It can apply.

  When the regenerative power RGL of the low voltage battery 24 is set to zero, the output voltage of the DC / DC converter 23 may be stopped instead of 12V. In this case, the regenerative power generated by motor generator 20 is not supplied to accessory 25, and power is supplied from low voltage battery 24 to accessory 25.

  In the above embodiment, the first map and the second map are stored in the storage unit of the electronic control unit 30, but the “map” mentioned here is the required regenerative power amount, as in the arithmetic expression or the table. As long as the regenerative electric energy RGL of the low voltage battery 24 can be calculated based on RG req, it may be included.

  The large regenerative power may be supplied to the high-voltage battery 22 as the required regenerative power amount RGreq increases without limiting the target charge amount of the motor generator 20. Whether to limit the target charge amount of motor generator 20 may be determined in consideration of the power generation performance of motor generator 20, the characteristics of high voltage battery 22, and the like.

  In the above embodiment, the target charge amount of the motor generator 20 is calculated according to the current (the current point in the series of control processing) output power amount Pout of the DC / DC converter 23, but the present invention is not limited thereto. For example, the regenerative electric energy RGH of the high voltage battery 22 is calculated according to the required regenerative electric energy RGreq as well as the regenerative electric energy RGL of the low voltage battery 24, and the regenerative electric energy RGL of the low voltage battery 24 and the regenerative electric energy of the high voltage battery 22 A value obtained by adding the RGH and the power consumption PC of the auxiliary device 25 may be used as the target power.

  The method of calculating the required regenerative energy RGreq in the above embodiment is merely an example. For example, in calculating the required regenerative electric energy RGreq, a part of the parameters exemplified in the above embodiment may be omitted, and other parameters may be used instead of or in addition to the parameters exemplified in the above embodiment. May be The same applies to the calculation of the predicted regeneration time Tp and the inter-vehicle distance LD.

DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... 1st pulley, 12 ... Transmission belt, 13 ... 2nd pulley, 20 ... Motor generator, 21 ... Inverter, 22 ... High voltage battery, 23 ... DC / DC converter, 24 ... Low voltage battery, 25 ... Complementary 30, electronic control unit 31, vehicle speed sensor 32, brake sensor 33, accelerator sensor 34, gyro sensor 35, millimeter wave radar,
IC: DC / DC converter output information, IH: high-voltage battery state information, IL: low-voltage battery state information, SP: vehicle speed, BR: brake pedal depression amount, AC: accelerator pedal depression amount, GY: attitude information , LD ... inter-vehicle distance, MS mg ... operation signal, MS c ... operation signal, RG req ... required regenerative energy, RGL ... regenerative energy to low voltage battery, RGL max ... high voltage regeneration to low voltage battery, PC ... power of auxiliary device Amount, Pout: Output power of DC / DC converter, RGH: Regenerated power to high-voltage battery, RGHmax: Maximum regenerated amount to high-voltage battery.

Claims (1)

A motor generator drivingly connected to an engine, a high voltage battery for supplying power to the motor generator, a DC / DC converter for stepping down and outputting power from the high voltage battery and the motor generator, voltage higher than that of the high voltage battery A hybrid system comprising: a low voltage battery having a large charging resistance per unit and to which power from the DC / DC converter is supplied, and a control unit controlling an output voltage of the DC / DC converter,
The control unit
The required regeneration power required for the motor generator is calculated according to the driving state of the vehicle, and the estimated duration of power regeneration in the motor generator is calculated.
The low voltage battery may be charged more preferentially than the high voltage battery if the predicted continuation time is equal to or greater than a predetermined specified time or if the required regenerative power amount is equal to or greater than a predetermined specified power amount. Control the DC / DC converter,
The DC / DC converter such that the high voltage battery is preferentially charged over the low voltage battery when the predicted continuation time is less than the specified time and the required regenerative power amount is less than the specified power amount. A hybrid system characterized by controlling