JP2004166367A - Battery controller of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery controller of a hybrid vehicle in which charge/discharge is controlled depending on the operating conditions. <P>SOLUTION: The battery controller of a hybrid vehicle comprising a power generating unit consisting of an engine 1, a generator 2, and a drive motor 4, and an energy storage unit 3 provided with batteries comprises first decision means (S503, S509) for making a decision whether the battery voltage of the energy storage unit 3 is lower than a first comparison voltage or not, means (S505, S511) for limiting power discharge from the energy storage unit 3 if the battery voltage is lower than the first comparison voltage, and a means (S501) for detecting whether the engine 1 is under starting operation through the generator 2 or not. During starting operation of the engine 1, power discharge by the power discharge limiting means is suppressed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a battery control device for a hybrid vehicle, and more particularly to a battery charge / discharge limit control.
[0002]
[Prior art]
A battery mounted on a hybrid vehicle needs to generate a high voltage, and a battery using an assembled battery in which many battery cells are connected in series is known. In such an assembled battery, control is performed to detect the voltage of each battery cell, disconnect the battery from the motor if any of the voltages becomes zero, and prohibit further discharge. In this case, the current supplied to the drive motor is cut off when the cell voltage becomes 0, so that the driving performance changes greatly and the driver feels a sense of discomfort.
[0003]
Therefore, in the conventional charge / discharge control device, the discharge current is limited in two stages, discharge limitation and discharge inhibition, to reduce a sense of discomfort given to the driver. Specifically, the battery cell voltage at which the discharge limitation is started is set to a voltage higher than the battery cell voltage at which the discharge is inhibited, and the discharge current value is limited when the battery cell voltage falls below the voltage. In addition, the battery cell voltage at which charging is started is set to a voltage lower than the battery cell voltage at which charging is prohibited, and the charging current value is limited when the battery cell voltage exceeds the voltage. As a result, the change in the driving force of the driving motor becomes gentle, and it is possible to reduce the sense of discomfort given to the driver (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-178225
[0005]
[Problems to be solved by the invention]
However, when the current is limited just before the prohibition of charging / discharging as in the above-described conventional technique, there is a case where the operation is adversely affected depending on the driving situation.
[0006]
For example, when the battery capacity is small when the engine is started, either the vehicle runs with the drive motor using the remaining small battery capacity or the vehicle stops. In such a case, if the discharge power is limited before the discharge is prohibited in order to suppress the uncomfortable feeling given to the driver as in the related art, even though the amount of power capable of starting the engine remains, the discharge power is limited. Therefore, there is a possibility that the vehicle stops.
[0007]
Therefore, an object of the present invention is to provide a battery control device for a hybrid vehicle that can perform charge / discharge control according to a driving situation.
[0008]
[Means for solving the problem]
The present invention relates to a battery control device for a hybrid vehicle including a power generation device including an engine and a generator, a power storage device including a battery, and a drive motor, wherein a voltage of a battery forming the power storage device is the first. A first determining means for determining whether the voltage is lower than a predetermined voltage. Further, when the first determining means determines that the voltage is lower than the first predetermined voltage, the discharge power limiting means for limiting discharge from the power storage device; Engine start detecting means for detecting whether or not the generator receiving electric power is starting. When the engine is being started, the limitation of discharge by the discharge power limiting unit is suppressed.
[0009]
Also, a hybrid vehicle includes an engine, a drive motor, a power storage device, and a stepped transmission, and transmits power of at least one of the engine and the drive motor to an output shaft via the stepped transmission. The battery control device is configured as follows.
First determining means for determining whether or not the voltage of the battery constituting the power storage device is lower than a first predetermined voltage; and determining that the voltage of the battery is lower than the first predetermined voltage. And a discharge power limiting means for limiting the discharge power from the power storage device when the determination is made. Further, there is provided torque cooperative control operation detecting means for detecting whether or not torque cooperative control for controlling torque generated by the engine and the drive motor is in operation so as to cancel a shift shock generated during a shift. In such a battery control device, when the torque coordination control is in operation, the limitation on the discharge by the discharge power limiting unit is suppressed.
[0010]
The hybrid vehicle further includes an engine, a drive motor, a power storage device, and a stepped transmission, and transmits at least one of the power of the engine and the drive motor to an output shaft via the stepped transmission. The battery control device is configured as follows. Second determining means for determining whether the voltage of a battery constituting the power storage device is higher than a second predetermined voltage; and determining whether the battery voltage is higher than a second predetermined value. And charging power limiting means for limiting charging power from the power storage device when the determination is made. Further, there is provided torque cooperative control operation detecting means for detecting whether or not torque cooperative control for controlling torque generated by the engine and the drive motor is in operation so as to cancel a shift shock generated during a shift. In such a battery control device, when the torque cooperative control is in operation, the limitation of charging by the charging power limiting unit is suppressed.
[0011]
[Action and effect]
When the engine is being started, by suppressing the discharge restriction by the discharge power restriction means, it is possible to increase the frequency at which the engine can be started while securing power.
[0012]
Further, when the torque cooperative control is in operation, the frequency at which the discharge power for generating the torque required to suppress the shift shock can be secured by suppressing the discharge limitation by the discharge power limiting means. Can be higher.
[0013]
Further, when the torque coordination control is in operation, by suppressing the charging limitation by the charging power limiting unit, the frequency at which the charging power for generating the torque required to suppress the shift shock can be recovered. Can be higher.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram of a hybrid vehicle used in the first embodiment. Here, a series hybrid vehicle is used. In the present embodiment, the possibility of overcharging / discharging is determined by determining whether each cell voltage is within a predetermined range in the cell controller 9, and the integrated controller 12 controls charging / discharging based on the result. Here, the possibility of overcharging / discharging is determined by the cell controller 9; however, the present invention is not limited to this. For example, a circuit that detects only the possibility of overdischarging is used, or a controller for performing discharge control is individually provided. It may be prepared for.
[0015]
The power train includes an engine 1, a generator 2 which is directly connected to the engine 1, converts an output of the engine 1 into electric power, and performs cranking at the time of starting, and a storage unit which is a storage unit of electric power generated by the generator 2. The device 3 is provided. Further, a drive motor 4 driven by the power generated by the generator 2 or the power stored in the power storage device 3 or both powers is provided. The torque of the drive motor 4 is transmitted to the tire 5 via the final gear 6, and is used as a driving force for the vehicle.
[0016]
The control system includes an integrated controller 12 that integrally controls the hybrid vehicle, and an engine controller 7 that controls the throttle opening to realize a torque command value of the engine 1 output from the integrated controller 12. In addition, a generator controller 8 that performs vector control of the generator 2 so that the rotation speed of the generator 2 becomes equal to the rotation speed command value output from the integrated controller 12 is provided. Further, a drive motor controller 11 that performs vector control of the torque of the drive motor 4 based on the motor torque command value output from the integrated controller 12 is provided.
[0017]
The power storage device 3 includes a cell controller 9 and a power storage device controller 10 as a control system. The cell controller 9 includes a circuit that suppresses a variation in the voltage of each cell of the power storage device 3 including a plurality of batteries and that determines whether there is a possibility of overcharging and discharging. Information on the state of each cell is sent to the integrated controller 12. The power storage device controller 10 detects the voltage and current of the entire power storage device 3, calculates the power that can be input to and output from the power storage device 3, and sends the calculated power to the integrated controller 12.
[0018]
FIG. 2 shows a circuit configuration of the cell controller 9. FIG. 2A shows an outline, and FIG. 2B shows a detailed circuit.
[0019]
Each of a plurality of series-connected battery cells 1n (n = 1, 2, 3,...) Constituting the power storage device 3 has a current bypass 2n (n = 1, 2, 3) for suppressing a variation in voltage between the cells. , 3 ...). Also, an overcharge detection circuit 3n (n = 1, 2, 3,...) For detecting the possibility of overcharging of the battery cell 1n, and for detecting the possibility of overdischarging of the battery cell 1n. Of overdischarge detection circuits 4n (n = 1, 2, 3,...). Further, a cell output unit 5n (n = 1, 2, 3,...) That outputs detection results of the overcharge detection circuit 3n and the overdischarge detection circuit 4n for each cell, and overcharge or overdischarge of the power storage device 3 And an output unit 6 for outputting whether or not there is a possibility.
[0020]
The output from the output unit 6 is sent to the integrated controller 12. Here, a signal of 1 is sent to the integrated controller 12 when at least one of overcharging and overdischarging may occur in any one of the battery cells 1n, and 0 otherwise.
[0021]
As shown in FIG. 2B, the current bypass channel 2n for suppressing the variation of the cell voltage includes an internal resistor and a Zener diode (for example, a reverse voltage of 3.8 V) in parallel with the battery. Here, when the cell voltage exceeds the reverse voltage, a current flows through the internal resistance. For this reason, when charging is continued, the voltage of the battery cell 1n becomes close to the reverse voltage, and the variation in the voltage of each battery cell 1n can be suppressed.
[0022]
The overcharge detection circuit 3n includes a voltage converter, and outputs a signal (for example, 1) to the cell output unit 5n when the voltage at each battery cell 1n becomes higher than the second comparison voltage. Here, the second comparison voltage is a charging limit start voltage at which there is a possibility that the battery cell 1n may be overcharged and charging power limit is started. At this time, the second comparison voltage is switched depending on whether the p-type MOS transistor is made conductive. When the p-type MOS transistor is turned on, the second comparison voltage becomes low (for example, the second comparison voltage is 3.9 [V]), and when it is not turned on, the second comparison voltage becomes high ( For example, the second comparison voltage is 4.1 [V]. Whether the p-type MOS transistor is made conductive or not is determined by the integrated controller 12 according to the running state. The signal reflected in the determination is sent to the cell controller 9 to make the p-type MOS transistor conductive.
[0023]
The overdischarge detection circuit 4n includes a voltage converter, and outputs a signal (for example, 1) to the cell output unit 5n when the voltage of each battery cell 1n becomes lower than the first comparison voltage. Here, the first comparison voltage is a discharge limit start voltage at which there is a possibility that the battery cell 1n may be overdischarged, and the limitation of the discharge power is started. At this time, the first comparison voltage is switched depending on whether or not the n-type MOS transistor is made conductive. When the n-type MOS transistor is turned on, the first comparison voltage decreases (for example, the first comparison voltage is 2 [V]), and when the n-type MOS transistor is not turned on, the first comparison voltage increases (for example, for example). The first comparison voltage is 2.3 [V]). Whether to make the n-type MOS transistor conductive is determined by the integrated controller 12 according to the running state, and a signal reflecting the determination is sent to the cell controller 9.
[0024]
In the overdischarge detection circuit 4n of the present invention, the first comparative voltage is set to a high state when the engine 1 is not started, and the first comparative voltage is set to a low state when the engine 1 is started. When any one of the voltages of the voltage cells 1n becomes lower than the first comparison voltage, the output signal of the overdischarge detection circuit 4n is set to 1 and is output to the cell output unit 5n to start limiting the discharge power. .
[0025]
Here, in the cell controller 9 of FIG. 2, a signal from the integrated controller 12 for switching whether or not to conduct the n-type and p-type MOS transistors is common. Therefore, as shown in FIG. 3, if the p-type MOS transistor is conductive, the n-type MOS transistor is not conductive, and if the p-type MOS transistor is not conductive, the n-type MOS transistor is conductive. is there. That is, when the first comparison voltage is set to be low, the value of the second comparison voltage is set to be high, thereby making it difficult to limit discharge and charging. When it is desired to provide different restrictions on the discharging side and the charging side, signals different from those in FIG. 2 may be provided separately for switching the conduction state of the n-type and p-type MOS transistors.
[0026]
Also, since the output signal from each battery cell 1n is only one from the cell output unit 5n, whether the output signal of the overcharge circuit 3n is 1 or the output signal of the overdischarge detection circuit 4n is 1 Can not judge. Therefore, based on the voltage of the power storage device 3 detected by the power storage device controller 10, the output from the overcharge detection circuit 3n is 1 if the voltage is close to full charge, and if the voltage is low, the overdischarge detection is performed. It is estimated that the output from the circuit 4n is 1. Based on the estimation result, it is determined whether overdischarge or overcharge may occur. Here, as another state, the output signal of the overcharge circuit 3a of one cell 1a is 1, the output signal of the overdischarge circuit 4b of another cell 1b is 1, and the output unit 6 from the cell controller 9 is 1. The case is conceivable. In other words, there is a case where the possibility of overcharge and overdischarge is occurring at the same time. However, as shown in FIG. 2, since a bypass circuit 2n for suppressing the variation in voltage between cells is provided, such a state occurs. Can be considered very unlikely.
[0027]
Next, the discharge control method of the present embodiment will be described with reference to the flowchart of FIG. Here, it is determined that the overdischarge is likely to occur, and the voltage at which the discharge limit is started is set as the value of the first comparison voltage. When the engine 1 is started, a low first comparison voltage is set as a discharge limit start voltage, and otherwise, a high first comparison voltage is set as a discharge limit start voltage. This process is repeated at regular intervals, for example, every 100 [msec].
[0028]
In step S401, a limit value Pd_lmt [kW] of the discharge power extracted from the power storage device 3 is obtained. This can be determined according to the flowchart of FIG. 5 for calculating the discharge power limit value.
[0029]
In step S501, it is determined whether the engine 1 is being started.
This determination can be made based on an engine start command value from the integrated controller 12. If it is determined that the engine 1 is being started, the process proceeds to step S502, and the comparison voltage switch of the overdischarge detection circuit 4n is turned on. This comparison voltage changeover switch is an n-type MOS transistor of the overdischarge detection circuit 4n provided in each cell of FIG. 2 and is turned on when turned on. As a result, the first comparison voltage serving as a reference value for detecting the possibility of occurrence of overdischarge is set to a low value.
As a result, the limitation of the discharge power is not started until the cell voltage becomes a low value, and even when the power storage amount of the power storage device 3 is small, a large amount of power can be temporarily taken out. The comparison voltage switch is switched based on a signal from the integrated controller 12.
[0030]
In step S503, it is determined whether or not there is a cell whose output signal of the overdischarge detection circuit 4n is 1. That is, it is determined whether or not there is a battery cell 1n that may be over-discharged. Here, as described above, based on the voltage of the power storage device 3 obtained by the power storage device controller 10, it is estimated whether the signal from the output unit 6 indicates the possibility of overcharge or the possibility of overdischarge. .
[0031]
If it is determined in step S503 that there is a battery cell 1n that may be overdischarged, the process proceeds to step S504. In step S504, a calculation cycle t_sample [sec] is added to the count-up timer value t [sec]. Here, the count-up timer value t [sec] indicates a continuation time in which it is determined that there is a possibility of overdischarge. That is, it indicates the time during which the limitation of the discharge power continues. The initial value is 0.
[0032]
Next, in step S505, a discharge power limit value Pd_lmt [kW] is calculated based on the count-up timer value t [sec]. Specifically, the value of the discharge power limit value Pd_lmt corresponding to the count-up timer value t is read from the table shown in FIG. This table is set in advance by performing an experiment or the like, and has a value close to the upper limit of the power that can be extracted from the power storage device 3 within a range that does not cause overdischarge. Since the power that can be taken out decreases as the discharge time elapses, the value of the discharge power limit value Pd_lmt is also set to decrease as the count-up timer value t increases, and finally the discharge prohibition (Pd_lmt = 0 [kW]). By calculating the discharge power limit value Pd_lmt in such a manner, the limit amount of the discharge power gradually changes from the start of the discharge limit to the prohibition of the discharge, and is supplied to the drive motor 4. A sudden change in power is suppressed, and the driver does not feel uncomfortable.
[0033]
On the other hand, if it is determined in step S503 that the output of the overdischarge detection circuit 4n is not 1, that is, that the voltages of all the battery cells 1n are higher than the first comparison voltage, the process proceeds to step S506. At this time, it is determined that there is no possibility of overdischarge, and in step S506, the count-up timer value t [sec] is reset. Next, in step S507, a discharge power limit value Pd_lmt [kW] is set. Here, for example, dischargeable power of power storage device 3 is set as discharge power limit value Pd_lmt [kW]. The dischargeable power is a power value that can be extracted from the power storage device 3. The dischargeable power can be calculated from the following equation (1).
[0034]
(Equation 1)
(Dischargeable power) = minimum voltage x (open voltage-minimum voltage) / internal resistance ... (1)
The open-circuit voltage can be obtained by obtaining the relationship with the state of charge (SOC) of the power storage device 3 in advance by experiment and storing it in a table as shown in FIG. Similarly, the internal resistance can be obtained using a table as shown in FIG. The minimum voltage is determined by restrictions on the usable voltage of the battery and the vehicle such as an inverter, and is, for example, 200 [V] here.
[0035]
On the other hand, when it is determined in step S501 that the engine 1 is not being started, the process proceeds to step S508. In step S508, the comparison voltage switch is turned off, and the first comparison voltage is set to a high value. As a result, the discharge power is limited from the time when the voltage value of each cell is relatively high.
[0036]
Proceeding to step S509, it is determined whether the output signal of the comparator of the overdischarge detection circuit 4n is "1". Here, when the output is 1, one of the cell voltage values is lower than the first comparison voltage. In this case, the process proceeds to step S510, and the count-up timer value t [sec] is set to a value obtained by adding the calculation cycle t_sample [sec]. In step S511, a discharge power limit value Pd_lmt [kW] is calculated according to the count-up timer value t [sec]. Here, similarly to the processing in step S505, the discharge power limit value Pd_lmt is calculated using the table shown in FIG.
[0037]
On the other hand, if it is determined in step S509 that the output signal of the over-discharge detection circuit 4n is not 1, the cell voltage state does not require discharge limitation. Therefore, the process proceeds to step S512, where the count-up timer value t [sec] is reset, and in step S513, the dischargeable power is set as the discharge power limit value Pd_lmt [kW]. This can be obtained from the above equation (1).
[0038]
As described above, when the engine 1 is not started, the first comparison voltage is set to a high state, and when the engine 1 is started, the first comparison voltage is set to a low state. When the output signal of any one of the overdischarge detection circuits 4n becomes 1, that is, when the value of any of the cell voltages becomes lower than the first comparison voltage, the limitation of the discharge power is started. For this reason, conventionally, even when the engine 1 is started, the discharge power is limited in the same manner as in other cases, whereas when the engine 1 is started, more power is used for the start. it can. As a result, even when the remaining battery level is low, the possibility that the engine 1 fails to start is low, that is, the frequency at which the engine 1 can be started increases.
[0039]
After the discharge power limit value Pd_lmt [kW] is set in step S401 according to the driving situation, in step S402, the other drive motors and accessories are used so that the electric power is used for starting the engine 1. Limit the power consumed. This is controlled according to the flowchart relating to the calculation of the drive motor / auxiliary equipment consumption limit value in FIG.
[0040]
In step S601, a limit value Pdrv_lmt [kW] (≧ 0) of the power that can be consumed by the drive motor 4 is obtained from the following equation (2).
[0041]
[Equation 2]
Pdrv_lmt = Pd_lmt−Pstr−Paux_min−Pmrg (2)
Here, Pstr [kW] is the power consumed when cranking using the generator 2 at the time of starting the engine 1, Paux_min [kW] is the power consumption of the auxiliary equipment necessary for traveling such as power steering, Pmrg [kW] is the power for the margin (for example, 2 [kW]). By limiting the power consumption of the drive motor 4 by the limit value Pdrv_lmt, the power required for the engine start 1 is reliably ensured. However, Pstr = 0 [kW] except when the engine is started. Note that the power consumption of the drive motor 4 can be limited by limiting the command torque to the drive motor 4.
[0042]
In step S602, the power consumption limit value Pdrv_lmt [kW] of the drive motor 4 is compared with the drive motor power consumption Pdrv [kW]. Here, the drive motor power consumption Pdrv [kW] is obtained from the following equation (3).
[0043]
[Equation 3]
Pdrv = (VSP * Tm * Gtotal) / (60 * 60 * R) (3)
Here, VSP [km / h] indicates the vehicle traveling speed, Tm [Nm] indicates the motor torque for realizing the driving required by the driver, Gtotal indicates the total reduction ratio, and R [m] indicates the effective radius of the tire.
[0044]
If it is determined in step S602 that the drive motor power consumption limit value Pdrv_lmt [kW] is larger than the drive motor power consumption Pdrv [kW], the process proceeds to step S603. In step S603, the auxiliary power consumption limit value Paux_lmt [kW] is obtained from the following equation (4).
[0045]
(Equation 4)
Paux_lmt = Pdrv_lmt−Pdrv (4)
The accessory power consumption limit value Paux_lmt [kW] obtained here is a power value that can be used for the operation of accessories such as an air conditioner that does not directly affect traveling. By limiting the power consumption of the auxiliary devices by the limit value Paux_lmt, power for realizing the operation requested by the driver is secured.
[0046]
On the other hand, in step S602, when it is determined that the drive motor power consumption limit value Pdrv_lmt [kW] is smaller than the drive motor power consumption Pdrv [kW], it is determined that there is no power to be used for the accessories. Therefore, the operation of the air conditioner and the like is stopped in step S604.
[0047]
In this way, the electric power that can be used for the accessories is limited, and the electric power that is used in the drive motor 4 is secured as much as possible. As a result, more electric power can be used for driving, and the frequency with which the required operation can be performed can be increased.
[0048]
Next, in step S403, a command value for the engine 1, the generator 2, and the drive motor 4 obtained so as not to exceed the limit value of the discharge power is realized.
[0049]
FIG. 8 shows the battery voltage, the electric power, and the generator torque in the case where the control is performed in this manner when the engine 1 is started. FIG. 7 shows a battery voltage, electric power, and generator torque at the time of starting the engine 1 when a conventional control method is used as a comparative example.
[0050]
In the present embodiment, when the engine 1 is started, the discharge limit start voltage (first comparison voltage) is lower than in the related art, so that even when the charged amount is small, power can be taken out without performing the discharge limit. Frequency increases. As a result, in the conventional method, the power taken out at the time of starting the engine 1 is limited, and the torque of the generator 2 is also suppressed. However, in the present embodiment, the necessary power can be taken out to generate the torque of the generator 2. . As a result, the frequency of starting the engine 1 increases.
[0051]
Next, effects of the present embodiment will be described.
[0052]
In a battery control device for a hybrid vehicle including a power generating device including the engine 1 and the generator 2, a power storage device 3 including a battery, and a drive motor 4, a voltage of a battery forming the power storage device 3 is equal to a first voltage. The first determining means (S503, S509) for determining whether the voltage is less than the comparison voltage. If the first determination means determines that the voltage is lower than the first comparison voltage, the discharge power limiting means (S505, S511) for limiting discharge from the power storage device 3 and the engine 1 Engine start detecting means (S501) for detecting whether or not the generator 2 receiving electric power from the device 3 is starting. When the engine 1 is being started, the limitation of discharge by the discharge power limiting means is suppressed. Thus, even when the amount of power stored in power storage device 3 is small during start-up of engine 1, the electric power can be used for start-up of engine 1, so that the frequency of start-up of engine 1 increases.
[0053]
When the engine 1 is being started, the value of the first comparison voltage is set to be low, thereby suppressing the discharge limitation. Thus, the frequency at which the battery cell voltage becomes lower than the first comparison voltage can be suppressed, and thus, it is difficult to limit the discharge. That is, the frequency at which the power used when cranking using the generator 2 is limited is reduced, and the frequency at which the engine 1 can be started is increased.
[0054]
Further, during the start of the engine 1, the electric power used for the drive motor 4 is limited. As a result, it is possible to suppress the electric power secured for starting the engine 1 from being consumed by the drive motor 4 instead of starting the engine 1. As a result, the power used to start the engine 1 can be increased, and the frequency at which the engine 1 can be started can be increased.
[0055]
Further, during the start of the engine 1, the electric power used for the auxiliary equipment of the vehicle that is not involved in the start of the engine 1 is limited. As a result, it is possible to suppress the electric power secured for starting the engine 1 from being consumed not by the engine 1 but by accessories.
As a result, the power used to start the engine 1 can be increased, and the frequency at which the engine 1 can be started can be increased.
[0056]
Further, when the engine 1 is being started, the limit amount of the discharge power is reduced.
By performing the control shown in the present embodiment, when the first comparison voltage is lower than when the first comparison voltage is higher, the discharge power limit value Pd_lmt [kW] for a certain cell voltage becomes higher. That is, the limit of the discharge power for a certain cell voltage is reduced. This is because, when the first comparison voltage is set low, the discharge limit is started later than when the first comparison voltage is set high, so that the count-up timer value t [sec] when the same cell voltage is reached is reached. Is smaller.
[0057]
That is, in the present embodiment, not only the power for starting is increased by delaying the discharge limit start timing during engine startup than the normal timing, but also the discharge limit during engine startup is smaller than the normal limit. By doing so, the power for starting is increased.
[0058]
Note that the discharge restriction may be suppressed only by setting the discharge power restriction value Pd_lmt [kW] high at the time of starting the engine 1 and reducing the discharge restriction amount. That is, at the time of starting the engine 1, by setting the discharge power limit value Pd_lmt [kW] higher than usual, the power that can be extracted from the power storage device 3 can be increased. In this case, a first table in which a relatively high discharge power limit value Pd_lmt [kW] is set and a second table in which a relatively low discharge power limit value Pd_lmt [kW] is set are prepared. In the flow of the calculation of the discharge power limit value described above, instead of setting the first comparison voltage to a low value in step S502, the discharge power limit value Pd_lmt is calculated from the first table in step S505. Further, instead of setting the first comparison voltage to a high value in step S508, the discharge power limit value Pd_lmt is calculated from the second table in step S511. As a result, it is possible to increase the power taken out when starting the engine 1.
[0059]
Next, a second embodiment will be described. The configuration is the same as that of the first embodiment, and only different portions of the control method will be described below.
[0060]
Here, in addition to the first embodiment, even when the engine 1 is not started, the voltage for starting the discharge limitation is switched according to the ambient temperature. Here, when the ambient temperature is low when the engine 1 is started, that is, when the engine 1 is cold, the viscosity of the engine oil increases and the friction increases. Therefore, the output of the generator 2 for increasing the engine speed is required in order to overcome this friction. Further, since ignition or complete explosion due to a decrease in vaporized fuel is difficult, energy for rotating the generator 2 for a long time is required.
[0061]
Therefore, the temperature of the engine oil is estimated from the ambient temperature, and the voltage at which the discharge limitation is started is set according to the engine oil temperature. Here, as shown in FIG. 19, when the ambient temperature is low, here, when the ambient temperature is lower than 0 ° C., the discharge limit is not applied to the voltage Va for starting the discharge limit at the normal temperature (0 to 25 ° C.). The starting voltage Vb is set high. In the present embodiment, the high voltage value Vb is set to the value of the first comparison voltage (eg, 2.3 [V]) when the comparison voltage switch of the discharge detection circuit 2n in the circuit of FIG. 2 is turned off. And On the other hand, the voltage value Va for starting the discharge limitation at the normal temperature is set to the value of the comparison voltage (for example, 2.0 [V]) when the comparison voltage switch is turned on. Here, in the circuit configuration shown in FIG. 2, the discharge limiting start voltage (first comparison voltage) is set to two stages. However, if a circuit capable of continuously changing the first comparison voltage is used, the atmosphere becomes more atmospheric. It is possible to set a discharge limiting start voltage corresponding to the temperature.
[0062]
Next, a flow for performing the above control will be described. The flowchart of FIG. 4 is used for the entire flow, as in the first embodiment. FIG. 9 shows a flow of calculating the discharge power limit value in step S401.
[0063]
If it is determined in step S901 that the engine 1 is starting, the process proceeds to step S902, and the first comparison voltage is set to a low value Va. In the present embodiment, the comparison voltage switch is turned on. Hereinafter, the same control as in the first embodiment is performed. On the other hand, if it is not determined in step S901 that the engine 1 is being started, the process proceeds to step S914 to detect the ambient temperature. Next, in step S915, it is determined whether the detected ambient temperature is lower than a predetermined temperature (here, 0 ° C.).
[0064]
If the ambient temperature is equal to or higher than 0 ° C., it is determined that the electric power required when starting the engine 1 is small, and the process proceeds to step S916, where the voltage Vc for starting the discharge limitation shown in FIG. 19 is set to a low voltage. . Here, since the first comparison voltage is switched by turning on the comparison voltage switch, the voltage Va is set to the same voltage as when the engine 1 is started. After that, the discharge power limit value Pd_lmt [kW] is obtained as in the first embodiment. On the other hand, if the ambient temperature is lower than 0 ° C., it is predicted that a large amount of electric power is required when the engine 1 is started, and the process proceeds to step S908. Here, in order to secure the charged amount of the power storage device 3, as shown in FIG. 19, the voltage Vb for starting the discharge limitation is set to a high value (the comparative voltage switch OFF). After that, the discharge power limit value Pd_lmt [kW] is obtained as in the first embodiment.
[0065]
Here, the first comparison voltage is set in two stages, and the discharge limit start voltage Va during the start of the engine 1 and the discharge limit start voltage Vc at the normal time when the ambient temperature is high are the same. It is also possible to set the comparison voltage in three stages and to set the voltage according to each of the three stages. At this time, Va <Vc <Vb can be set. Further, as described above, the first comparison voltage may be changed continuously, and the discharge limiting start voltage may be set higher as the ambient temperature is lower. Further, here, the switching of the discharge limiting start voltage is performed according to the ambient temperature, but may be performed according to the temperature of engine oil or cooling water.
[0066]
Next, effects of the present embodiment will be described. Here, the following effects can be obtained in addition to the effects of the first embodiment.
[0067]
During normal operation in which the ambient temperature is high, the power of the power storage device 27 can be used to the last, thereby ensuring the operability of the vehicle. When the ambient temperature is high, the amount of electric power required to start the engine 1 is small. Therefore, even when the remaining amount of the power storage device 27 decreases when the ambient temperature is high, there is not much problem. On the other hand, when the ambient temperature is low, it is expected that a large amount of electric power will be required to start the engine 1. Therefore, the electric power limitation during the normal operation is started early, and the remaining amount of the power storage device 27 is maintained at a high level. I do. As a result, even if the engine 1 is started when the ambient temperature is low, the possibility of the engine 1 failing to start is reduced.
[0068]
Next, a third embodiment will be described. Here, a parallel hybrid vehicle is used, and the configuration is shown in FIG.
[0069]
The power train includes an engine 21. Also, a part of the output of the engine 21 which is directly connected to the engine 21 is converted into electric power, or a driving torque is generated by using electric power stored in a power storage device 27 which will be described later, thereby providing torque assist generated by the engine 21. The motor 22 is provided. Further, a stepped automatic transmission 23 (hereinafter referred to as a transmission 23) fastened to the output shaft of the motor 22 and a reduction gear 24 are provided, and the torque generated by the engine 21 and the motor 22 is transmitted to the tire 25 via the final gear 26. Is transmitted. A power storage device 27 is connected to the motor 22 to supply power to the motor 22.
[0070]
As in the first embodiment, the control system includes an integrated controller 33 for controlling the entire system, an engine controller 29 for controlling the engine 21, a cell controller 28 as a control system for the power storage device 29, and a power storage device controller 31. The motor controller 30 includes a motor controller 30 that vector-controls the torque of the motor 22 based on the motor torque command value output from the integrated controller 33. Further, a transmission controller 32 is provided, and the integrated controller 33 controls the transmission 23 in accordance with the accelerator operation of the driver and the vehicle speed so as to realize the gear position calculated so as to meet the driving force request of the driver.
[0071]
Further, the integrated controller 33 performs torque cooperative control using the engine 21, the motor 22, and the transmission 23 at the time of shifting. This is to control the torque generated by the engine 21 and the motor 22 so as to suppress the shift shock generated during the shift, thereby realizing a smooth shift.
[0072]
FIG. 11 shows the state of each torque and electric power at the time of the torque cooperative control performed during the conventional shift. For example, in the case of an upshift that reduces the gear ratio, the input rotation speed must be reduced to the synchronous rotation speed in the returned gear ratio, and in the case of a downshift that increases the gear ratio, the input rotation speed Needs to be increased to the synchronous speed at the speed ratio after the speed change. The sensible torque accompanying such a change in the input rotational speed appears in the output shaft torque, which may be a shift shock. Therefore, the torque shock is suppressed by adjusting the electric power supplied to the motor 22 in the torque cooperative control.
[0073]
As shown in FIG. 11, when performing the torque cooperative control, power is supplied to the motor 22 or power is recovered from the motor 22. However, when the battery voltage (charged amount) is small, there is a possibility that the discharge is limited, and the drive torque may not be generated sufficiently. When the battery voltage (charged amount) is large, there is a possibility that charging is restricted, and there is a case where regenerative torque cannot be generated sufficiently.
[0074]
Accordingly, in the present embodiment, as shown in FIG. 12, the voltage value (first comparison voltage) for starting the discharge limitation during the shift is set to a low value to suppress the discharge limitation and suppress the shift shock. To secure the discharge power required to generate the driving torque. Similarly, during a gear shift, the voltage value (second comparison voltage) for starting the charge limitation is set to a high value to suppress the charge limitation and generate a regenerative torque required to suppress a shift shock. Secure charging power.
[0075]
The circuit configuration of FIG. 2 is used for the cell controller 28 as in the first embodiment. As described with reference to FIG. 2, since the signal for switching whether the n and p-type MOS transistors are made conductive is common, there is a relationship between the conductive state of each MOS transistor and the comparison voltage as shown in FIG. Here, since both the limitation of charging and the limitation of discharging are suppressed during the gear shifting, the control can be performed by a common signal as shown in FIG. The integrated controller 33 receives the comparison result using the comparison voltage, and obtains the charge and discharge limit values.
[0076]
Next, a control method according to the present embodiment will be described with reference to the flowcharts in FIGS. This process is executed at a constant period, for example, every 100 [msec].
[0077]
In step S101, a limit value of the discharge power and the charge power from power storage device 27 is obtained based on the voltage of each cell. FIG. 14 shows a flow of the power limit value calculation.
[0078]
Here, instead of the determination during the start of the engine in step S501 in the discharge power limit value calculation flow (FIG. 5) used in the first embodiment, a determination is made in step S111 as to whether or not a shift is being performed. If the shift is in progress, the process proceeds to step S112, in which the comparison voltage switch is turned on to set the first comparison voltage to a low value and the second comparison voltage to a high value. Thus, the discharge restriction is not performed until the cell voltage becomes a low voltage value, and the charging restriction is not performed until the cell voltage becomes a high voltage value. On the other hand, if it is determined in step S111 that the gear is not being shifted, the comparative voltage switch is turned off, and charging and discharging are gradually limited from a relatively early stage.
[0079]
Also, as in the first embodiment, when the discharge power limit value Pd_lmt [kW] is obtained in steps S115 and S123 (corresponding to S505 and S511 in FIG. 5), the charge power limit value is subsequently determined in steps S116 and S124. Pc_lmt [kW] is obtained.
This can be obtained by searching the map shown in FIG. 21 based on the count-up timer value t [sec]. This map is set in advance by an experiment or the like so that the charging power limit value decreases as the count-up timer value t [sec] increases in order to prevent overcharging.
[0080]
Further, as in the first embodiment, in steps S118 and S126, when the dischargeable power is obtained as the discharge power limit value Pd_lmt [kW] (corresponding to S507 and S513 in FIG. 5), subsequently, in steps S119 and S127, The chargeable power is determined as the limit value Pc_lmt [kW] of the charge power. The chargeable electric power can be obtained from equation (5).
[0081]
(Equation 5)
(Chargeable power) = Maximum voltage x (Maximum voltage-Open voltage) / Internal resistance ... (5)
The open circuit voltage can be obtained by previously obtaining the relationship with the state of charge (SOC) of the power storage device 27 through experiments or the like, and storing the obtained value as a table as shown in FIG.
Similarly, the internal resistance can be obtained using a table as shown in FIG. The maximum voltage is determined by the restriction on the voltage use range of the power storage device 27, and is, for example, 400 [V] here.
[0082]
After setting the limit start voltages of the charging power and the discharging power in this way, in step S102, the power consumed by the other auxiliary devices is reduced so that the torque coordination control at the time of shifting the motor 22 can be performed using the discharging voltage. Restrict. This control method will be described with reference to the flow of the auxiliary equipment consumption limit value calculation shown in FIG.
[0083]
In step S131, the supplementary power consumption limit value Paux_lmt [kW] (≧ 0) can be obtained from the following equation (6).
[0084]
(Equation 6)
Paux_lmt = Pd_lmt-Pdrv-Ptrs (6)
Here, Ptrs [kW] is electric power used for torque cooperative control, and can be obtained in advance by experiments or the like. Further, Pdrv [kW] is electric power consumed for driving in the motor 22, and can be obtained from Expression (7).
[0085]
[Equation 7]
Pdrv = (VSP * Tm * G * Gf) / (60 * 60 * R) (7)
Here, VSP [km / h] is the vehicle traveling speed, Tm [Nm] is the motor torque, G is the speed ratio of the stepped automatic transmission before the speed change, Gf is the speed ratio of the transmission 23, and R [m] is Indicates the effective radius of the tire.
[0086]
After limiting the power consumption of the accessories in this way, the process proceeds to step S103, and the command values for the engine 21, the motor 22, and the transmission 23, which are determined not to exceed the limit values, are realized.
[0087]
Next, effects of the present embodiment will be described.
[0088]
A battery control device for a hybrid vehicle that includes an engine 21, a motor 22, a power storage device 27, and a transmission 23 and transmits at least one of the power of the engine 21 and the motor 22 to an output shaft via the transmission 23. The configuration is as follows. The power storage device 27 includes first determination means (S113, S121) for determining whether or not the voltage of the battery constituting the power storage device 27 is lower than the first comparison voltage. In addition, when the first determining means determines that the battery voltage is lower than the first comparison voltage, the first determining means includes discharge power limiting means (S115, S123) for limiting the discharge power from the power storage device 27. . Further, there is provided a torque cooperative control operation detecting means (S111) for detecting whether or not torque cooperative control for controlling the torque generated by the engine 1 and the motor 22 is in operation so as to cancel a shift shock generated during a shift. . In such a battery control device, when the torque cooperative control is in operation, the discharge limitation by the discharge power limiting unit is suppressed. As a result, it is possible to prevent the electric power necessary for causing the motor 22 to generate the driving torque in order to suppress the shift shock from being limited.
[0089]
Here, the value of the first comparison voltage is set low. This makes it difficult to limit the discharge, so that the frequency at which the power for suppressing the shift shock is limited can be reduced, and the frequency at which the driver feels uncomfortable with the shift shock can be reduced.
[0090]
The second determination means (S113, S121) for determining whether the voltage of the battery constituting the power storage device 27 is higher than the second comparison voltage, and the second determination means determines that the battery voltage is equal to the second voltage. And charging power limiting means (S116, S124) for limiting the charging power from the power storage device 27 when it is determined that the voltage is higher than the comparison voltage.
Further, there is provided a torque cooperative control operation detecting means (S111) for detecting whether or not torque cooperative control for controlling the torque generated by the engine 21 and the motor 22 is in operation so as to cancel a shift shock generated during a shift. . When the torque cooperative control is in operation, the charging limitation by the charging power limiting unit is suppressed. As a result, it is possible to prevent the charging power required for causing the motor 22 to generate the regenerative torque in order to suppress the shift shock from being limited.
[0091]
Here, the value of the second comparison voltage is set high. This makes it difficult to limit charging, so that the frequency at which the power for suppressing the shift shock is limited can be reduced, and the frequency at which the driver feels uncomfortable with the shift shock can be reduced.
[0092]
In this case, since the torque cooperative control is performed at the time of shifting, it is determined whether or not the gear is being shifted to determine whether the torque cooperative control is being performed. However, it is determined whether the signal of the torque cooperative control is output. You may decide. Also, in the present embodiment, similarly to the first embodiment, the discharge limitation can be suppressed by reducing the discharge limit amount. In addition, the charge limitation can be suppressed by reducing the charge limitation amount. Further, during shifting, by limiting the electric power used for the auxiliary equipment of the vehicle that is not involved in starting the engine 21, electric power for suppressing a shift shock can be secured.
[0093]
As described above, the present invention is not limited to the above embodiment, and it goes without saying that various changes can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a hybrid vehicle used in a first embodiment.
FIG. 2 is a configuration diagram of a cell controller used in the first embodiment.
FIG. 3 is a diagram illustrating a relation between a conduction state of a transistor used in the first embodiment and a comparison voltage.
FIG. 4 is a control flow used in the first embodiment.
FIG. 5 is a control flow for calculating a discharge power limit value in the first embodiment.
FIG. 6 is a flowchart of calculating a consumption limit value of a drive motor / auxiliary equipment in the first embodiment.
FIG. 7 is a diagram showing changes in battery voltage, power, and generator torque according to a conventional control method.
FIG. 8 is a diagram showing changes in battery voltage, power, and generator torque in the first embodiment.
FIG. 9 is a control flow for calculating a discharge power limit value according to the second embodiment.
FIG. 10 is a schematic view of a hybrid vehicle used in a third embodiment.
FIG. 11 is a diagram showing changes in output shaft torque and the like by a conventional control method.
FIG. 12 is a diagram illustrating changes in output shaft torque and the like in a third embodiment.
FIG. 13 is a control flow used in the third embodiment.
FIG. 14 is a control flow for calculating a discharge power limit value in the third embodiment.
FIG. 15 is a flowchart for calculating a consumption limit value of auxiliary equipment in the third embodiment.
FIG. 16 is a diagram showing a discharge power limit value with respect to a time-up counter value.
FIG. 17 is a diagram showing a relationship between SOC and open circuit voltage.
FIG. 18 is a diagram showing a relationship between SOC and internal resistance.
FIG. 19 is a diagram showing a relationship between an ambient temperature and a discharge limit start voltage.
FIG. 20 is a diagram showing a charging power limit value with respect to a time-up counter value.
[Explanation of symbols]
1 engine
2 generator
3 Power storage device
4 Drive motor
9 Cell Controller
12 Integrated controller
21 Engine
22 motor
23 transmission
28 Cell Controller
33 Integrated Controller
4n overdischarge detection circuit
S503, 509, 113, 121 ... first judgment means
S505, 511, 115, 123 ... discharge power limiting means
S501: Engine start detection means
S111: Torque cooperative control operation detecting means
S113, 121: Second determination means
S116, 124: Charging power limiting means

Claims (8)

In a battery control device of a hybrid vehicle including a power generation device including an engine and a generator, a power storage device including a battery, and a drive motor,
First determining means for determining whether or not the voltage of a battery constituting the power storage device is lower than a first predetermined voltage;
A discharge power limiting unit configured to limit discharge from the power storage device when the first determining unit determines that the voltage is lower than the first predetermined voltage;
Engine start detection means for detecting whether the engine is being started by the generator receiving power from the power storage device,
A battery control device for a hybrid vehicle, wherein when the engine is being started, restriction of discharge by the discharge power restriction unit is suppressed. 2. The battery control device for a hybrid vehicle according to claim 1, wherein when the engine is being started, the first predetermined voltage is set to a low value to suppress a discharge limitation. 3. 2. The battery control device for a hybrid vehicle according to claim 1, wherein when the engine is being started, the limitation on the discharge is suppressed by reducing the limit amount of the discharge power. 3. The battery control device for a hybrid vehicle according to claim 1, wherein when the engine is being started, electric power used for the drive motor is limited. 2. The battery control device for a hybrid vehicle according to claim 1, wherein when the engine is being started, electric power used for accessories of the vehicle not involved in the engine start is limited. 3. The battery control device for a hybrid vehicle according to claim 1, wherein the first predetermined voltage is set based on an ambient temperature. Battery control for a hybrid vehicle including an engine, a drive motor, a power storage device, and a stepped transmission, and transmitting at least one of the power of the engine and the drive motor to an output shaft via the stepped transmission. In the device,
First determining means for determining whether or not the voltage of a battery constituting the power storage device is lower than a first predetermined voltage;
When the battery voltage is determined to be lower than the first predetermined voltage by the first determining means, a discharging power limiting means for limiting the discharging power from the power storage device, To cancel, torque cooperative control operation detecting means for detecting whether torque cooperative control for controlling the torque generated by the engine and the drive motor is in operation,
A battery control device for a hybrid vehicle, wherein when the torque cooperative control is in operation, the restriction of discharge by the discharge power restriction unit is suppressed. A battery for a hybrid vehicle including an engine, a drive motor, a power storage device, and a stepped transmission, and transmitting at least one of the power of the engine and the drive motor to an output shaft via the stepped transmission. In the control device,
Second determining means for determining whether a voltage of a battery constituting the power storage device is higher than a second predetermined voltage;
When the second determination unit determines that the battery voltage is higher than a second predetermined value, a charging power limiting unit that limits charging power from the power storage device;
A torque cooperative control operation detecting means for detecting whether or not torque cooperative control for controlling torque generated by the engine and the drive motor is in operation so as to cancel a shift shock generated during a shift,
A battery control device for a hybrid vehicle, wherein when the torque coordination control is in operation, charging limitation by the charging power limiting unit is suppressed.

Images