JP6383278B2 - Power supply unit - Google Patents

Description

  The present invention relates to a power supply unit in which an alternator generates electric power by using rotation of an engine of a vehicle as a power source and supplies the electric power to a battery.

  In the vehicle, for example, when starting the engine, a battery is provided to supply power to the starter. Also, the alternator generates electric power using the engine rotation as a power source, the battery is charged by the generated electric power, and the state of charge (SOC) is maintained at the target power storage rate that is the target of the power storage rate. Is done.

  Further, a technology for changing a target power storage rate according to a driving mode desired by a driver and a driving environment of the vehicle (for example, Patent Document 1), a target power storage of an assembled battery with respect to an assembled battery in which a plurality of cells are connected in series. Technology for adjusting the power storage rate between cells by increasing the rate (for example, Patent Document 2), Technology for changing the target power storage rate according to the degree of clutch friction when the vehicle is stopped (for example, Patent Reference 3) discloses a technique (for example, Patent Document 4) that adjusts the storage ratio between cells by increasing the target storage ratio of the assembled battery when a voltage abnormality between a plurality of cells is detected. .

JP 2008-279803 A JP 2005-278249 A JP 2013-119317 A JP 2005-278248 A

  As described above, while the vehicle is running, the battery is controlled (charge / discharge control) so that the storage rate is maintained at the target storage rate. However, once the engine is stopped, the storage rate decreases due to natural discharge while the engine is stopped, and deviates from the target storage rate. Therefore, at the time of starting the engine in the vehicle, so-called supplementary charging is performed to forcibly gradually increase the storage rate of the battery that has decreased due to spontaneous discharge, and after completion of the supplementary charging, switching to charge / discharge control is performed.

  However, conventionally, if the storage rate does not reach the target storage rate when the auxiliary charge is completed, the storage rate is reduced until the target storage rate is reached, regardless of whether the storage rate is at a level that hinders driving. Forced charging to increase gradually was performed. If such rapid charging is performed, the alternator's power generation during that time becomes an engine load, resulting in a problem that fuel efficiency cannot be improved.

  In view of such a problem, an object of the present invention is to provide a power supply unit that can suppress an increase in engine load due to forced charging after completion of auxiliary charging and can efficiently charge a battery.

  In order to solve the above problems, a power supply unit of the present invention includes a battery provided in a vehicle, an alternator that generates electric power using the rotation of the engine of the vehicle as a power source, and supplies the generated electric power to at least the battery, After starting the engine, after satisfying a predetermined condition in the auxiliary charge mode for gradually increasing the battery charge rate of the battery and in the auxiliary charge mode, the battery charge rate is set to the target charge rate with a predetermined value as a target charge rate An alternator control unit that controls the output of the alternator based on the target storage rate maintenance mode to be maintained, and the alternator control unit sets the battery storage rate to a predetermined value when a predetermined condition is satisfied in the auxiliary charging mode. If not, execute the target storage rate maintenance mode with the storage rate of the battery when the predetermined condition is satisfied as the target storage rate, The charge rate maintained mode, characterized by deriving the charge rate of the discharge current of the battery relatively large estimated by than the charging current.

  When the battery storage rate reaches a predetermined value, the alternator control unit may execute the target storage rate maintenance mode with the predetermined value as the target storage rate.

  The alternator control unit may reduce the ratio between the coefficient multiplied by the discharge current and the coefficient multiplied by the charging current when the battery storage rate reaches a predetermined value.

  If the alternator control unit determines that the shift range is any of the R range, the N range, and the P range, the predetermined value may be set as the target power storage rate even if the predetermined condition is satisfied in the auxiliary charge mode.

  According to the present invention, an increase in engine load due to forced charging can be suppressed after completion of auxiliary charging, and the battery can be charged efficiently.

It is the functional block diagram which showed the structure of the electric power supply unit. It is explanatory drawing which showed the control system of the target electrical storage rate maintenance mode. It is explanatory drawing for demonstrating the specific operation | movement of the target electrical storage rate maintenance mode. It is explanatory drawing for demonstrating auxiliary charge mode. It is explanatory drawing for demonstrating the other example of a target electrical storage rate maintenance mode. It is explanatory drawing for demonstrating the target electrical storage rate maintenance mode in this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Power supply unit 1)
FIG. 1 is a functional block diagram showing the configuration of the power supply unit 1. In FIG. 1, the solid line indicates the flow of power, and the broken line indicates the flow of control signal. The power supply unit 1 includes an engine 10, an alternator 12, a battery 14, a vehicle load 16, a current sensor 18, a voltage sensor 20, and a control unit 22.

  The engine 10 is a power source of the vehicle and rotates drive wheels via a clutch and a transmission. The alternator 12 is connected to the rotation shaft of the engine 10 directly or via a pulley mechanism, and generates electric power using the rotation of the engine 10 as a power source. Specifically, the field current is supplied to the field coil of the alternator 12 by the rotation of the engine 10, and an induced current of a three-phase alternating current is generated. Then, the field current of the field coil is adjusted through a regulator or the like, and the generated voltage (output voltage) is controlled mainly to 14V. Further, the alternator 12 performs engine power generation that actively generates power by inputting torque (power generation torque) from the engine 10, and regenerative power generation that generates power by inputting torque (braking torque) from the drive wheels or the transmission side. Is done. In the former, the engine 10 consumes fuel for the power generation, but in the latter, this braking torque contributes to the braking of the wheels and no fuel is consumed. The generated electric power is charged in the battery 14 and consumed as the electric system of the engine 10 and the vehicle load 16.

  The battery 14 is connected to the alternator 12 and accumulates (charges) the electric power generated by the alternator 12. Further, when electric power is required by the vehicle load 16 such as the engine 10 or an auxiliary machine, for example, when electric power is supplied to the starter when the engine 10 is started, the battery 14 uses the accumulated electric power to the engine 10 or the vehicle load 16. Is supplied (discharged).

  The current sensor 18 measures a current input / output (charge / discharge) to / from the battery 14 and transmits the measured current value to the control unit 22. The voltage sensor 20 measures the terminal voltage of the battery 14 and transmits the measured value to the control unit 22.

  The control unit 22 includes a central processing unit (CPU), a ROM that stores programs, a RAM as a work area, a semiconductor integrated circuit including an information holding unit that holds information necessary for running the vehicle, and the like. The sensor value is read and the entire power supply unit 1 is controlled through LIN (Local Interconnect Network) communication. In addition, the control unit 22 executes a program stored in the ROM, and functions as a functional unit such as the range determination unit 40, the storage rate deriving unit 42, and the alternator control unit 44.

  The range determination unit 40 determines which speed change range (forward range (D range), reverse range (R range), neutral range (N range), parking range (P range)) of the vehicle is set. Here, each shift range operates as follows. That is, in the D range, the forward clutch is engaged and the reverse clutch is released. In the R range, the forward clutch is released and the reverse clutch is engaged. In the N range, both the forward clutch and the reverse clutch are released. In the P range, both the forward clutch and the reverse clutch are released, and the parking lock mechanism is operated.

  The storage rate deriving unit 42 integrates the current value of the current sensor 18 to derive the storage rate (SOC). Further, the storage rate deriving unit 42 sequentially holds the derived storage rate in association with the derivation time in the information holding unit so as to hold the storage rate when the engine 10 is stopped. In the present embodiment, the storage rate is derived by integration of the current value, but based on the voltage of the voltage sensor 20, the current storage rate can also be directly derived. Therefore, the storage rate deriving unit 42 also uses the storage rate based on the voltage to determine the validity of the storage rate based on the current value.

  The alternator control unit 44 controls the generated voltage by adjusting the regulator of the alternator 12 and the like. Hereinafter, the control mode (target power storage rate maintenance mode, auxiliary charge mode) of the power storage rate of the battery 14 by the alternator control unit 44 will be described in detail.

(Target storage rate maintenance mode)
The battery 14 has a lower storage rate due to power supply to the engine 10 and the vehicle load 16. Therefore, the battery 14 is charged from the alternator 12 to replenish the storage rate. However, if the battery 14 is always charged from the alternator 12 in order to prevent a reduction in the storage rate, the power generated by the alternator 12 becomes an engine load, resulting in a decrease in fuel consumption. Therefore, the alternator control unit 44 uses the predetermined value set in advance as a target power storage rate that is a target of the power storage rate, and controls the power generation voltage of the alternator 12 so that the power storage rate of the battery 14 is maintained at the target power storage rate. (Target power storage rate maintenance mode).

  FIG. 2 is an explanatory diagram showing a control system in the target power storage rate maintenance mode. As shown in FIG. 2, in the target storage rate maintenance mode, the alternator 12 and the like are controlled according to the difference between the target storage rate and the storage rate of the battery 14, and the charging current to the battery 14 and the discharging current from the battery 14 are controlled. To control. Specifically, when the difference between the target storage rate and the storage rate of the battery 14 is within a predetermined storage rate range (for example, 95 ± 1%), the alternator control unit 44 determines the power generation voltage of the immediately preceding alternator 12 or the like. When the control state is maintained and the range of the predetermined power storage rate is exceeded, charge / discharge control is performed with a control amount proportional to the value.

  However, here, two concepts of a virtual power storage rate and an actually measured power storage rate are used as the power storage rate of the battery 14. The virtual power storage rate and the measured power storage rate both correspond to the integration of the current value of the current sensor 18 as the power storage rate, but the input processing of the integration is different. The measured power storage rate integrates the current value as it is, and shows the actual power storage rate itself, whereas the virtual power storage rate integrates after multiplying the current value by an arbitrary coefficient. Here, a positive current value (charging current value) is multiplied by a coefficient α in the vicinity of 1, and a negative current value (discharge current value) is multiplied by a coefficient β in the vicinity of 1.

  For convenience of explanation, assuming that the coefficient α and the coefficient β are 1, the virtual power storage rate and the actually measured power storage rate both indicate the current power storage rate of the battery 14 itself. Therefore, according to the control system in the target power storage rate maintenance mode, the virtual power storage rate can be maintained at the target power storage rate by appropriate charge / discharge control based on the difference between the target power storage rate and the virtual power storage rate.

  However, in the present embodiment, the values of the coefficient α and the coefficient β are arbitrarily set. For example, it is assumed that the coefficient β multiplied by the discharge current is 1.01, and the coefficient β multiplied by the charge current is higher than the coefficient α = 1.00 (the discharge current is estimated to be relatively larger than the charge current). In this case, the negative current value (discharge current value) is integrated by a difference between the coefficients β and 1 larger than the actual current value acquired by the current sensor 18, and the virtual power storage rate is the original power storage rate. It is estimated to be smaller than the actual measured power storage rate. As a result, when trying to maintain the virtual storage rate at the target storage rate, the charge / discharge command is biased to the positive side (charging side) from the original command, and the actual storage rate (corresponding to the measured storage rate) gradually increases. . Here, the average rate of increase of the storage rate per unit time is referred to as the first rate of increase. As described above, the configuration in which the actually measured power storage rate is gradually increased can avoid the natural discharge in the battery 14 and the deterioration of the power storage performance with time.

  However, the measured storage rate will eventually reach the maximum storage rate (for example, 100%) of the battery 14 only by gradually increasing the measured storage rate. Therefore, the alternator control unit 44 monitors the actual storage rate in addition to the virtual storage rate. When the actual storage rate reaches the maximum storage rate, the alternator control unit 44 rewrites the virtual storage rate with the actual storage rate. Thus, since the virtual power storage rate deviates from the target power storage rate, the measured power storage rate can be reduced. In the present embodiment, since the measured power storage rate is rewritten every time the measured power storage rate reaches the maximum power storage rate, the battery 14 is overcharged while avoiding spontaneous discharge in the battery 14 and deterioration of power storage performance over time. Can be prevented.

  FIG. 3 is an explanatory diagram for explaining a specific operation in the target power storage rate maintenance mode. As described above, the alternator control unit 44 sets a predetermined value (for example, 95%) as the target power storage rate, and maintains the virtual power storage rate at the target power storage rate as shown in FIG.

  Therefore, the alternator control unit 44 discharges the battery 14 when the virtual power storage rate rises to, for example, + 1% or more with respect to the target power storage rate, and the virtual power storage rate becomes, for example, -1% or less with respect to the target power storage rate. When the battery 14 is lowered, the battery 14 is charged. Then, as shown at time A in FIG. 3B, when the actual storage rate reaches the maximum storage rate, the virtual storage rate is rewritten to the actual storage rate. Therefore, as shown in FIG. 3A, the value of the virtual power storage rate gradually changes from the time point A and gradually returns to the target power storage rate.

(Supplementary charging mode)
As described above, while the vehicle is running, alternator control unit 44 performs charge / discharge control so that the storage rate of battery 14 is maintained at the target storage rate in the target storage rate maintenance mode. However, once the engine 10 is stopped (ignition off), the storage rate decreases due to natural discharge while the engine 10 is stopped, and deviates from the target storage rate. Therefore, when the engine 10 is started (ignition is turned on), supplementary charging for forcibly and gradually increasing the power storage rate of the battery 14 that has decreased due to natural discharge is performed, and after completion of the supplementary charging, switching to charge / discharge control is performed.

  FIG. 4 is an explanatory diagram for explaining the auxiliary charging mode. Specifically, first, as shown in FIG. 4, when the engine 10 is started, the storage rate deriving unit 42 reads the storage rate (95% here) held in the information holding unit when the engine 10 is stopped. Then, the power storage rate deriving unit 42 obtains a soak time from when the engine 10 is stopped (the time when the power storage rate was last held) to when the engine 10 is started, and stores power per unit time when the engine 10 is stopped. The estimated decrease in rate is multiplied by the soak time, and the result (8% here) is subtracted from the storage rate (95%) when engine 10 is stopped. In this way, the power storage rate (87% here) at the start of the engine 10 shown in FIG. 4 is derived.

  Subsequently, the alternator control unit 44 determines the second rate of increase (rapid speed) so that the storage rate reaches the target storage rate (for example, 95%) based on the storage rate (for example, 87%) at the start of the engine 10. Charge) for a predetermined time continuously. Here, the second rate of increase is an average rate of increase of the storage rate per unit time when the output voltage of the alternator 12 is set to a voltage at which the battery 14 is always charged regardless of the storage rate of the battery 14, And it is a value larger than the first increase rate. In this way, the storage rate of the battery 14 can be gradually increased to approach the target storage rate. When such auxiliary charging is completed, the alternator control unit 44 switches the auxiliary charging mode to the target storage rate maintaining mode and performs charge / discharge control as shown in FIG.

  FIG. 5 is an explanatory diagram for explaining another example of the target power storage rate maintenance mode. As described above, the alternator control unit 44 performs charging so that the storage rate reaches the target storage rate based on the storage rate at the start of the engine 10, but depending on the state of the vehicle at the start of the engine 10 As shown in FIG. 5, there are cases where the storage rate (for example, 91%) of the battery 14 at the completion of the auxiliary charging is less than the target storage rate (for example, 95%).

  Conventionally, when a predetermined condition (for example, a predetermined time elapses) is satisfied in the auxiliary charge mode, if the power storage rate does not reach the target power storage rate in this way, until the power storage rate reaches the target power storage rate, FIG. As shown in FIG. 4, for example, forced charging forcibly increasing the power storage rate at a second rate of increase similar to that of auxiliary charging has been performed. When rapid charging is performed in this way, the power generation of the alternator 12 during that period becomes an engine load, resulting in a decrease in fuel consumption.

  Therefore, in the present embodiment, forced charging is avoided after completion of auxiliary charging, and an increase in engine load due to forced charging is suppressed, and the battery 14 is efficiently charged.

  FIG. 6 is an explanatory diagram for explaining the target power storage rate maintenance mode in the present embodiment. The alternator control unit 44 satisfies a predetermined condition (for example, a predetermined time elapse) in the auxiliary charging mode, and when the auxiliary charging is completed, as shown in FIG. 6A, the storage rate (for example, 91%) of the battery 14 6 is less than the target power storage rate, as shown by a white arrow in FIG. 6, the battery power storage rate (for example, 91%) at the time of completion of auxiliary charging or an arbitrary value less than or equal to the battery 14 power storage rate is set as the target power storage rate. The target power storage rate maintenance mode is executed.

  That is, the alternator control unit 44 does not perform the forced charging described with reference to FIG. 5, and uses the battery storage rate (for example, 91%) at the completion of auxiliary charging, which is smaller than the original predetermined value, as a target storage rate. Charge / discharge control is performed to maintain the power storage rate at the target power storage rate.

  Here, the above-described forced charging is not performed, and the battery charging rate at the completion of the auxiliary charging is set as the target charging rate, so that rapid charging due to the second rate of increase is avoided, and the power generation of the alternator 12 is unnecessary. The load is prevented. As a result, fuel consumption can be improved.

  However, the original target power storage rate (for example, 95%) cannot be maintained simply by setting the target power storage rate to be lower than the predetermined value, which is the battery 14 storage rate at the time of completion of auxiliary charging. Therefore, as described with reference to FIG. 3, the alternator control unit 44 controls the measured storage rate to gradually increase by arbitrarily setting the values of the coefficient α and the coefficient β. Then, a target power storage rate maintenance mode is performed in which a predetermined value is the target power storage rate.

  However, here, a coefficient β (for example, 1.05) larger than the coefficient β (for example, 1.01) of the original target power storage rate maintenance mode is used. Therefore, the average rate of increase of the storage rate per unit time is a third rate of increase that is greater than the first rate of increase. In this way, by increasing the coefficient β, the virtual power storage rate is estimated to be smaller than the measured power storage rate that is the original power storage rate. As a result, the measured storage rate can be quickly brought close to the original target storage rate.

  Further, as shown in FIG. 6B, the alternator control unit 44, when the storage rate (actually measured storage rate) of the battery 14 reaches the original target storage rate, the target storage with the original predetermined value as the target storage rate. Assuming that the rate maintenance mode is possible, the target storage rate is switched from the storage rate of the battery 14 at the time of completion of the auxiliary charging to the original predetermined value, and the coefficient β is lowered from 1.05 to 1.01, for example. In this way, the target power storage rate maintenance mode is performed with a gentle slope that should be inherent.

  In this way, it is possible to shift to the original target power storage rate maintenance mode without improving the above-described forced charging, that is, while avoiding rapid charging due to the second rate of increase, thereby improving fuel consumption.

  However, if the range determination unit 40 determines that the shift range is not the D range but the R range, the N range, or the P range, there is a possibility that the ignition is turned off. Even if the above condition is satisfied, the target storage rate is set to the original predetermined value, and the battery 14 is prevented from deteriorating by performing rapid charging at the second increase rate.

  In addition, when the storage rate after completion of the auxiliary charging is equal to or less than a predetermined threshold (for example, 80%), rapid charging at the second rate of increase may be performed until the vehicle is fully charged in order to support smooth running of the vehicle. .

  As described above, in this embodiment, it is possible to suppress an increase in engine load due to forced charging after completion of auxiliary charging, and to efficiently charge the battery 14, and as a result, improve fuel consumption. Can do.

  Also provided are a program that causes the computer to function as the power supply unit 1 and a storage medium such as a computer-readable flexible disk, magneto-optical disk, ROM, CD, DVD, or BD on which the program is recorded. Here, the program refers to data processing means described in an arbitrary language or description method.

  In the embodiment described above, the control unit 22 has been described with an example in which the CPU, the ROM, and the RAM cooperate to operate each functional unit. However, the present invention is not limited to this, and an FPGA (Field-Programmable Gate Array) is used. ) Or an ASIC (Application Specific Integrated Circuit).

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  INDUSTRIAL APPLICABILITY The present invention can be used for a power supply unit in which an alternator generates electric power using rotation of a vehicle engine as a power source and supplies the electric power to a battery.

DESCRIPTION OF SYMBOLS 1 Electric power supply unit 10 Engine 12 Alternator 14 Battery 16 Vehicle load 22 Control unit 40 Range determination part 42 Power storage rate derivation part 44 Alternator control part

Claims (4)

A battery provided in the vehicle;
An alternator that generates electric power using the rotation of the engine of the vehicle as a power source, and supplies the generated electric power to at least the battery;
After the engine is started, an auxiliary charge mode for gradually increasing the battery charge rate of the battery, and after satisfying a predetermined condition in the auxiliary charge mode, the battery charge rate of the battery is set with a predetermined predetermined target charge rate. An alternator control unit for controlling the output of the alternator based on a target power storage rate maintenance mode for maintaining the target power storage rate;
With
The alternator control unit, when the predetermined condition is satisfied in the auxiliary charge mode, when the battery storage rate of the battery is less than the predetermined value, the storage rate of the battery when the predetermined condition is satisfied is a target power storage The target power storage rate maintenance mode is executed as a rate,
In the target power storage rate maintenance mode, the power supply unit derives the power storage rate by estimating the discharge current of the battery relatively larger than the charging current.   2. The power supply unit according to claim 1, wherein when the battery storage rate of the battery reaches the predetermined value, the alternator control unit executes the target power storage rate maintenance mode using the predetermined value as a target power storage rate. .   3. The electric power according to claim 1, wherein the alternator control unit lowers a ratio of a coefficient multiplied by a discharge current and a coefficient multiplied by a charging current when the storage rate of the battery reaches the predetermined value. Supply unit.   When the alternator control unit determines that the shift range is any one of the R range, the N range, and the P range, even if the predetermined condition is satisfied in the auxiliary charging mode, the predetermined value is set as the target power storage rate. The power supply unit according to claim 1, wherein the power supply unit is a power supply unit.

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