JP5474600B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply device mounted on a vehicle.

  In order to improve the fuel efficiency of the vehicle, the alternator is actively generated during deceleration to collect electrical energy, and then the auxiliary machine is operated using the collected electrical energy during subsequent acceleration or steady running. A so-called micro hybrid vehicle has been developed in which the power generation of the engine is stopped to reduce the engine load (see, for example, Patent Document 1). In this micro-hybrid vehicle, since the generated current of the alternator is actively changed, it is necessary to grasp the generated current of the alternator. Further, since the battery (power storage unit) is actively charged and discharged, it is necessary to grasp the charge / discharge current of the battery.

JP 2004-225649 A

  However, in order to grasp both the generated current and the charge / discharge current, it is necessary to attach a current sensor to the alternator and the battery. As described above, the incorporation of the two current sensors into the vehicle power supply device is a factor that causes an increase in cost of the vehicle power supply device.

  An object of the present invention is to achieve cost reduction of a vehicle power supply device.

A vehicle power supply device according to the present invention is a vehicle power supply device including a generator connected via a connection point, a first power storage unit, and an electrical load, wherein the first connection unit connects the connection point and the generator. wiring and a second wiring that connects the first power storage unit and the connection point, and a third line which connects the electric load to the connection point, the current detection for detecting a current value of said first wiring means, before Symbol voltage detecting means for detecting a voltage drop value of the second wiring, on the basis of said voltage drop value and the current value, the resistance calculation means for calculating a wiring resistance value before Symbol second wiring, wherein based on the voltage drop value the wiring resistance value, and a current estimating means for estimating a current value of the detected have such pre-gastric Symbol second wiring by said current detecting means, provided in the third wiring, the generator and Switch to the open state to disconnect the electrical load from the first power storage unit And a second power storage unit connected to the third wiring between the electrical load and the separation switch, and the current detecting means switches the separation switch to an open state. And detecting the current value used for calculating the wiring resistance value, and the voltage detecting means is used for calculating the wiring resistance value in a state where the separation switch is switched to an open state. The voltage drop value detected is detected .

A vehicle power supply device according to the present invention is a vehicle power supply device including a generator connected via a connection point, a first power storage unit, and an electrical load, wherein the first connection unit connects the connection point and the generator. Current detection means for detecting a current value of the wiring, a second wiring connecting the connection point and the first power storage unit, a third wiring connecting the connection point and the electric load, and Voltage detection means for detecting a voltage drop value of the first wiring, resistance calculation means for calculating a wiring resistance value of the first wiring based on the current value and the voltage drop value, and the voltage drop value Current estimation means for estimating the current value of the first wiring not detected by the current detection means based on the wiring resistance value, and the generator and the first power storage unit provided in the third wiring Switch to open state to disconnect the electrical load from And a second power storage unit connected to the third wiring between the electrical load and the separation switch, and the current detecting means switches the separation switch to an open state. And detecting the current value used for calculating the wiring resistance value, and the voltage detecting means is used for calculating the wiring resistance value in a state where the separation switch is switched to an open state. The voltage drop value detected is detected .

  According to the present invention, since the wiring resistance value of the first wiring can be calculated, the current value of the first wiring can be estimated by detecting the voltage drop value of the first wiring. Alternatively, since the wiring resistance value of the second wiring can be calculated, the current value of the second wiring can be estimated by detecting the voltage drop value of the second wiring. Thereby, since a current sensor can be reduced, it becomes possible to achieve cost reduction of the power supply device for vehicles.

It is the schematic which shows the structure of the vehicle provided with the vehicle power supply device which is one embodiment of this invention. It is explanatory drawing which shows the operating state of the power supply device for vehicles. (a) And (b) is explanatory drawing which shows the operating state of the power supply device for vehicles. It is the schematic which shows the power supply device for vehicles. It is the schematic which shows another power supply device for vehicles. It is the schematic which shows the vehicle power supply device which is other embodiment of this invention. It is the schematic which shows the power supply device for vehicles. It is the schematic which shows another power supply device for vehicles.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a vehicle 11 including a vehicle power supply device 10 according to an embodiment of the present invention. As shown in FIG. 1, an engine 12 and a transmission 13 are mounted on the vehicle 11. Drive wheels 16 are connected to the output shaft 14 of the transmission 13 via a differential mechanism 15. A starter motor 17 is assembled to the engine 12. Further, an alternator 18 as a generator is connected to the engine 12 via a drive belt 19.

  The illustrated vehicle 11 is a so-called micro-hybrid vehicle, and the vehicle 11 is mounted with a low-voltage regeneration system using an alternator 18. At the time of deceleration at which the depression of the accelerator pedal is released, the kinetic energy of the vehicle 11 is positively converted into electric energy and recovered by driving the alternator 18 to generate electricity. Further, during acceleration when the accelerator pedal is depressed or during steady running, power generation by the alternator 18 is stopped to reduce the engine load. In this manner, the fuel efficiency of the vehicle 11 is improved by controlling the alternator 18 so as not to increase the engine load.

The vehicle power supply device 10 is provided with a main battery 20 that is a first power storage unit. A starter motor 17 and an alternator 18 are connected to the main battery 20. Thus, the first battery system 21 is constituted by the main battery 20, the starter motor 17, and the alternator 18. The allowable voltage range of the main battery 20 and the alternator 18 constituting the first power supply system 21 is set to about 12 to 18V. That is, the upper limit voltage in the control of the main battery 20 and the alternator 18 is set to 18V.

  As the main battery 20, an electricity storage device having a small charge / discharge resistance and excellent cycle characteristics is used. Examples of such a power storage device include so-called rocking chair type power storage units such as a lithium ion battery, a lithium ion capacitor, an electric double layer capacitor, and a nickel metal hydride battery. Here, the rocking chair type power storage unit refers to a power storage unit that performs charging and discharging by reciprocating lithium ions, hydrogen ions, and the like between electrodes. Further, the power storage mechanism of the rocking chair type power storage unit is not accompanied by a change in physical structure (dissolution / deposition) of the electrode. For this reason, the rocking chair type power storage unit has a characteristic that charge / discharge resistance is small and cycle characteristics are excellent.

Further, the vehicle power supply device 10 is provided with a sub-battery 22 as a second power storage unit. An electrical component 26 such as a headlight 23, an ignition coil 24, and an electronic control unit 25 is connected to the sub-battery 22 as an electrical load. In this way, the second battery system 27 is configured by the sub-battery 22 and the electrical component 26. Note that the allowable voltage range of the sub-battery 22 and the electrical component 26 constituting the second power supply system 27 is set to about 12 to 15V. That is, the upper limit voltage in the control of the sub battery 22 and the electrical component 26 is set to 15V.

  As the sub-battery 22, the storage capacity of the sub-battery 22 in which an electric storage device having a predetermined storage capacity is used is set in consideration of the starting performance after leaving the vehicle for a predetermined period (for example, three months). As such an electric storage device, a so-called reserve electric storage body such as a lead storage battery having a large storage capacity at a low cost can be cited. Here, the reserve type power storage unit refers to a power storage unit that performs charge / discharge by dissolving ions in the electrolytic solution from the metal or the like of the electrode and precipitating the ions in the electrolytic solution on the electrode as metal or the like. In addition, the power storage mechanism of the reserve power storage unit is accompanied by a physical structural change (dissolution / deposition) of the electrode. For this reason, the reserve type power storage unit has characteristics that the charge / discharge resistance is large and the cycle characteristics are poor as compared with the rocking chair type power storage unit, but it is possible to use an inexpensive electrode material such as lead. The storage capacity is large. The sub-battery 22 is not limited to the reserve type power storage unit, and a rocking chair type power storage unit may be used as the sub-battery 22 as long as a predetermined power storage capacity can be secured at low cost.

  Further, as shown in FIG. 1, an energization line 30 is connected to the plus terminal of the alternator 18 as a first wiring. In addition, a current-carrying line 31 is connected to the positive terminal of the main battery 20 as a second wiring. Furthermore, a current-carrying line 32 is connected to the plus terminal of the electrical component 26 as a third wiring. These energization lines 30 to 32 are connected to each other through a common connection point 33. The energizing line 32 is provided with a separation switch 34 such as an n-channel FET. By switching the separation switch 34 to the connected state, the first power supply system 21 and the second power supply system 27 can be electrically connected. On the other hand, the first power supply system 21 and the second power supply system 27 can be electrically disconnected by switching the separation switch 34 to the open state. That is, the electrical component 26 can be disconnected from the alternator 18 and the main battery 20 by opening the separation switch 34.

  Hereinafter, the operating state of the vehicle power supply device 10 will be described. The control unit 35 that controls the vehicle power supply device 10 includes a CPU that executes a program, a ROM that stores programs, a RAM that temporarily stores data, input / output ports connected to various sensors, actuators, and the like. Has been. Examples of sensors connected to the control unit 35 include a brake switch 36 that detects whether the brake pedal is depressed, an accelerator opening sensor 37 that detects the amount of depression of the accelerator pedal, and an inhibitor switch 38 that detects the operation position of the select lever. There is a vehicle speed sensor 39 for detecting the vehicle speed. Further, the control unit 35 includes a current sensor 40 as current detecting means for detecting the current value of the energization line 31, a voltage sensor 41 for detecting the voltage at the plus terminal of the alternator 18, and a voltage sensor for detecting the voltage at the connection point 33. 42 is connected.

  FIG. 2 is an explanatory diagram showing an operating state of the vehicle power supply device 10. FIG. 2 shows a state during acceleration of the vehicle where the accelerator pedal is depressed or during steady running, that is, a state where the alternator 18 is not driven to generate electricity. FIGS. 3A and 3B are explanatory views showing the operating state of the vehicle power supply device 10. FIGS. 3A and 3B show a state during deceleration of the vehicle in which the depression of the accelerator pedal is released, that is, a state where the alternator 18 is driven to generate electricity. In FIG. 2 and FIG. 3, the power supply state is represented using black arrows.

  First, the control unit 35 calculates the state of charge SOCm of the main battery 20 based on the voltage, charge / discharge current, and temperature of the main battery 20. As a calculation method of the state of charge SOCm, for example, a calculation method described in JP-A-2005-201743 can be used. In this calculation method, the state of charge SOCc based on the integrated value of the charge / discharge current and the state of charge SOCv based on the estimated open-circuit voltage are calculated, and the state of charge SOCm and SOCv are weighted and combined to calculate the state of charge SOCm. It is a method to do. The method for calculating the state of charge SOCm is not limited to the above-described method, and the state of charge SOCm may be calculated using another calculation method.

  As shown in FIG. 2, when the accelerator pedal is depressed (accelerator ON), the control unit 35 sets the target power generation current of the alternator 18 to “0”, and the alternator 18 stops power generation. At this time, as shown in FIG. 3, the separation switch 34 is held in the connected state by the control unit 35, and the main battery 20 and the sub battery 22 are connected to the electrical component 26. Here, the voltage range in which the storage capacity of the main battery 20 can be exhibited is designed to be higher than the voltage range in which the storage capacity of the sub battery 22 can be exhibited. For this reason, power is mainly supplied from the main battery 20 to the electrical component 26, while power supply from the sub battery 22 is suppressed. In this way, by suppressing charging / discharging of the sub-battery 22, it is possible to prevent deterioration of the sub-battery 22 made of a reserve type power storage unit or the like. In addition, since the cycle characteristics of the main battery 20 made of a rocking chair type power storage unit are good, the main battery 20 does not deteriorate significantly even if it is charged and discharged frequently.

  Further, when the depression of the accelerator pedal is released (accelerator OFF), the control unit 35 sets the target generated current of the alternator 18 according to the vehicle speed. Then, the control unit 35 adjusts the generated voltage of the alternator 18 so that the target generated current can be obtained. In the power generation control of the alternator 18, it is important to increase the power generation amount of the alternator 18. Therefore, when the state of charge SOCm falls within a predetermined range, the control unit 35 switches the separation switch 34 to the open state. Here, as shown in FIG. 3A, by opening the separation switch 34, the first power supply system 21 and the second power supply system 27 are electrically disconnected. In this way, by separating the alternator 18 and the main battery 20 from the second power supply system 27 by opening the separation switch 34, the power generation voltage of the alternator 18 is set exceeding the upper limit voltage (15V) of the second power supply system 27. It becomes possible. As a result, the power generation amount of the alternator 18 can be increased. Even when the separation switch 34 is opened, power is supplied from the sub-battery 22 to the electrical component 26, so that the electrical component 26 can continue to operate normally.

  On the other hand, when the state of charge SOCm is out of the predetermined range, that is, when the state of charge SOCm is decreasing or rising, the control unit 35 switches the separation switch 34 to the connected state. Here, as shown in FIG. 3B, by connecting the separation switch 34, the first power supply system 21 and the second power supply system 27 are electrically connected. That is, in order to protect the second power supply system 27 whose upper limit voltage is 15V, the power generation voltage of the alternator 18 is limited to 15V or less. However, when the state of charge SOCm is low, the open voltage of the main battery 20 is low, so that a predetermined target generated current (for example, 200 A) can be obtained without raising the generated voltage to 15V. As described above, when a necessary generated current can be obtained without opening the separation switch 34, the alternator 18 is driven to generate electricity while the separation switch 34 is connected to suppress charging / discharging of the sub-battery 22. Further, when the state of charge SOCm is rising, the open voltage of the main battery 20 is high, so that it is difficult to obtain a sufficient generated current even if the generated voltage is raised to 15 V or higher. As described above, when a necessary generated current cannot be obtained even if the generated voltage is raised, the alternator 18 is driven to generate power while the separation switch 34 is connected to suppress charging / discharging of the sub-battery 22.

  Thus, when controlling the vehicle power supply device 10, it is necessary to grasp the charge / discharge current of the main battery 20 in order to calculate the state of charge SOCm of the main battery 20. Further, when controlling the vehicle power supply device 10, it is necessary to grasp the generated current of the alternator 18 in order to control the generated voltage of the alternator 18 toward the target generated current. However, assembling the current sensor to both the alternator 18 and the main battery 20 has been a factor in increasing the cost of the vehicle power supply device 10. Therefore, the control unit 35 of the vehicular power supply apparatus 10 estimates the power generation current of the alternator 18 as follows in order to reduce the current sensors previously provided in the alternator 18.

Hereinafter, the estimation control of the generated current executed by the control unit 35 will be described. FIG. 4 is a schematic diagram showing the vehicle power supply device 10. As shown in FIG. 4, the control unit 35 opens the separation switch 34 and guides the generated current I ₁ of the alternator 18 to the main battery 20 in order to obtain the wiring resistance value R ₁ of the energization line 30. By opening the separation switch 34 in this way, the generated current I ₁ and the charge / discharge current I ₂ can be matched. Then, the control unit 35 functioning as a voltage detection means is based on the voltage V _{1 at} the plus terminal of the alternator 18 detected by the voltage sensor 41 and the voltage V ₂ at the connection point 33 detected by the voltage sensor 42. A voltage drop value Vd (= V ₁ −V ₂ ) of the energization line 30 is calculated. Subsequently, the control unit 35 functioning as a resistance calculating means, based on the charging / discharging current (current value) I ₂ from the current sensor 40 and the calculated voltage drop value Vd, the energization line 30 according to the following equation (1). to the calculated wiring resistance R _1. Needless to say, the charge / discharge current I ₂ from the current sensor 40, the voltage V ₁ from the voltage sensor 41, and the voltage V ₂ from the voltage sensor 42 are detected values obtained at the same timing.
R ₁ = Vd / I ₂ (1)

As described above, the wiring resistance value R ₁ of the current supply line 30 is calculated, the control unit 35 stores the wiring resistance value R ₁ as data to be used during the current calculation. Then, the control unit 35 functioning as current estimation means can estimate the generated current I ₁ according to the following equation (2) by obtaining the voltage drop value Vd of the energization line 30. Note that the wiring resistance value R ₁ is periodically calculated and updated because it fluctuates due to aging and temperature environment.
I ₁ = Vd / R ₁ (2)

As described above, since the separation switch 34 is opened so that the generated current I ₁ and the charge / discharge current I ₂ coincide with each other, the charge / discharge current I ₂ detected by the current sensor 40 is used to generate power. It becomes possible to accurately obtain the wiring resistance value R ₁ of the energization line 30 through which the current I ₁ flows. Thereby, it is possible to accurately estimate the generated current I ₁ only by detecting the voltage drop value Vd. Therefore, the current sensor 40 on the alternator 18 side can be reduced, and the cost of the vehicle power supply device 10 can be reduced. Moreover, because adopting the small rocking chair type power storage unit of the charging resistor to the main battery 20, it is possible to increase significantly the generated current I ₁ of the alternator 18. Further, since the disconnect the electrical equipment 26 and the sub-battery 22 by opening the isolation switch 34, it is possible to increase significantly the generated current I ₁ of the alternator 18. Thus, since the generated current I ₁ can be increased (for example, 200 A), the voltage drop value Vd can be increased to accurately calculate the wiring resistance value R ₁ . Thereby, it becomes possible to accurately estimate the generated current I _1. In addition, by reducing the number of current sensors on the alternator 18 side, it is possible to reduce the size of the vehicle power supply device 10. By mounting such a small vehicle power supply device 10 in the engine room, it is possible to improve the collision safety performance and the pedestrian protection performance. Furthermore, by reducing the number of current sensors on the alternator 18 side, the reliability of the vehicle power supply device 10 can be improved.

In the above description, the current sensor 40 is provided in the energization line 31 on the main battery 20 side. However, the present invention is not limited to this, and the current sensor 40 may be provided in the energization line 30 on the alternator 18 side. In this case, the voltage sensor 41 that has detected the voltage at the positive terminal of the alternator 18 is reduced, and a voltage sensor that detects the voltage at the positive terminal of the main battery 20 is added. Then, the control unit 35 calculates the voltage drop value of the energization line 31 based on the voltage from each voltage sensor. Further, the control unit 35 calculates the wiring resistance value of the energization line 31 based on the generated current I ₁ from the current sensor and the calculated voltage drop value of the energization line 31. As described above, since the wiring resistance value of the energization line 31 is obtained, the control unit 35 can estimate the charge / discharge current I ₂ only by detecting the voltage drop value of the energization line 31.

  In the above description, the current sensor 40 is provided in the energization line 31 on the main battery 20 side or the energization line 30 on the alternator 18 side. However, the present invention is not limited to this. The number of sensors 40 may be reduced. Here, FIG. 5 is a schematic view showing another vehicle power supply device 50. 5, parts that are the same as the parts shown in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted.

As shown in FIG. 5, the vehicle power supply device 50 is provided with a voltage sensor 51 that detects the voltage V <b> 3 of the positive terminal of the main battery 20. The alternator 18 incorporates a regulator 52 as a protection circuit, and the regulator 52 limits the generated current I ₁ of the alternator 18 to a predetermined upper limit current value I _max (for example, 200 A) or less. In order to estimate the power generation current I ₁ and the charge / discharge current I ₂ of the vehicle power supply device 50 as described above, the control unit 53 performs the estimation control of the power generation current I ₁ and the charge / discharge current I ₂ as follows.

First, the control unit 53 opens the separation switch 34 and guides the generated current I ₁ of the alternator 18 to the main battery 20 in order to obtain the wiring resistance value R ₁ of the energization line 30. By opening the separation switch 34 in this way, the generated current I ₁ and the charge / discharge current I ₂ can be matched. In this case, as the generated current I ₁ of the alternator 18 reaches the upper limit current value I _max, the power generation voltage of the alternator 18 is raised to the upper limit voltage. That is, the generated current I ₁ and the charge / discharge current I ₂ are in a state that matches the upper limit current value I _max .

Then, the control unit 53 functioning as the first voltage detection means is based on the voltage V _{1 at} the plus terminal of the alternator 18 detected by the voltage sensor 41 and the voltage V ₂ at the connection point 33 detected by the voltage sensor 42. Thus, the first voltage drop value Vd ₁ (= V ₁ −V ₂ ) of the energization line 30 is calculated. Similarly, the control unit 35 functioning as the second voltage detection means includes the voltage V ₂ at the connection point 33 detected by the voltage sensor 42 and the voltage V _{3 at} the positive terminal of the main battery 20 detected by the voltage sensor 51. Based on the above, the second voltage drop value Vd ₂ (= V ₂ −V ₃ ) of the energization line 31 is calculated.

Subsequently, the control unit 53 functioning as the first resistance calculating means, based on the upper limit current value I _max and the calculated voltage drop value Vd ₁ , according to the following formula (3), the first wiring resistance value of the energization line 30. R ₁ is calculated. Similarly, the control unit 35 functioning as the second resistance calculating means, based on the upper limit current value I _max and the calculated voltage drop value Vd ₂ , the second wiring resistance value of the energization line 31 according to the following equation (4). to calculate the R _2.
R ₁ = Vd ₁ / I _max (3)
R ₂ = Vd ₂ / I _max (4)

As described above, when the wiring resistance value R ₁ of the energization line 30 is calculated, the control unit 53 stores the wiring resistance value R ₁ as data used when calculating the current. Then, the control unit 53 functioning as the first current estimating means can estimate the generated current I ₁ according to the following equation (5) by obtaining the voltage drop value Vd ₁ of the energization line 30. Similarly, the wiring resistance value R ₂ of the current-carrying line 31 is calculated, the control unit 53 stores the wiring resistance value R ₂ as data used during the current calculation. Then, the control unit 53 functioning as the second current estimating means, by obtaining a voltage drop value Vd ₂ energization line 31, it is possible to estimate the charge and discharge current I ₂ according to the following equation (6). Since the wiring resistance values R ₁ and R ₂ fluctuate due to secular change and temperature environment, the wiring resistance values R ₁ and R ₂ are periodically calculated and updated.
I ₁ = Vd ₁ / R ₁ (5)
I ₂ = Vd ₂ / R ₂ (6)

As has been described, can be used the upper limit current value I _max is limited by the regulator 52 of the alternator 18, obtains the wiring resistance R ₁ of the current-carrying line 30 and the wiring resistance value R ₂ of the current-carrying line 31 It becomes. As a result, it is possible to estimate the generated current I ₁ only by detecting the voltage drop value Vd ₁ , so that it is possible to reduce the current sensor on the alternator 18 side. Furthermore, since the charge / discharge current I ₂ can be estimated only by detecting the voltage drop value Vd ₂ , the current sensor on the main battery 20 side can be reduced. Thus, since two current sensors can be reduced, it is possible to achieve a significant cost reduction of the vehicle power supply device 50. Moreover, because adopting the small rocking chair type power storage unit of the charging resistor to the main battery 20, it becomes possible to increase the generated current I ₁ of the alternator 18 to the upper limit current value I _max. Further, since the disconnect the electrical equipment 26 and the sub-battery 22, it becomes possible to increase the generated current I ₁ of the alternator 18 to the upper limit current value I _max by opening the isolation switch 34. Thus, since the generated current I ₁ can be raised to the upper limit current value I _max, it is possible to accurately calculate the wiring resistance values R ₁ and R ₂ by enlarging the voltage drop values Vd ₁ and Vd _2. Become. Thus, the generated current I ₁ and discharge current I ₂ becomes possible to accurately estimate. Further, by reducing the two current sensors, it is possible to achieve downsizing of the vehicle power supply device 50. By mounting such a small vehicle power supply device 50 in the engine room, it is possible to improve the collision safety performance and the pedestrian protection performance. Furthermore, the reliability of the vehicle power supply device 50 can be improved by reducing the two current sensors.

  Moreover, the structure of the vehicle power supply device 50 described above can be described as follows as claims. A power supply device for a vehicle comprising a generator, a power storage unit and an electrical load connected via a connection point, a first wiring connecting the connection point and the generator, the connection point and the power storage unit The first wiring of the first wiring when the power generation current of the generator is raised to a predetermined upper limit current value, the second wiring for connecting the connection point, the third wiring for connecting the connection point and the electrical load, First voltage detecting means for detecting a voltage drop value, and second voltage detecting means for detecting a second voltage drop value of the second wiring when the generated current of the generator is raised to a predetermined upper limit current value First resistance calculating means for calculating a first wiring resistance value of the first wiring based on the upper limit current value and the first voltage drop value; and the upper limit current value and the second voltage drop value. Based on the second resistance calculation, the second wiring resistance value of the second wiring is calculated. Means, first current estimating means for estimating a current value of the first wiring based on the first voltage drop value and the first wiring resistance value, the second voltage drop value and the second wiring resistance value. And a second current estimating means for estimating a current value of the second wiring based on the above.

  By the way, although the vehicle power supply devices 10 and 50 described above are provided with the first power supply system 21 and the second power supply system 27, they are not limited to the vehicle power supply devices 10 and 50 having this configuration. You may apply this invention with respect to the power supply device for vehicles. Here, FIG. 6 is a schematic diagram showing a vehicle power supply device 60 according to another embodiment of the present invention. 6, parts that are the same as the parts shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 6, the energization line 61 is connected to the plus terminal of the alternator 18 as the first wiring. In addition, an energization line 62 is connected to the plus terminal of the electrical component 26 as a third wiring. These energization lines 61 and 62 are connected to each other via a connection point 63. That is, the alternator 18 and the electrical component 26 are connected via the energization lines 61 and 62 that bypass the main battery 20. The energization line 61 is provided with a first switch SW1 made of an n-channel FET or the like. Further, the connection point 63 and the positive terminal of the main battery 20 are connected via an energization line 64 as a second wiring. Further, the negative terminal of the main battery 20 and the plus terminal of the alternator 18 are connected via an energization line 65. Thus, the main battery 20 and the alternator 18 are connected in series. The energization line 65 is provided with a second switch SW2 made of an n-channel FET or the like. Furthermore, a ground line 66 is connected to the energization line 65 between the switch SW2 and the main battery 20. A connection point 67 between the switch SW2 and the main battery 20 is grounded by the ground line 66. The ground line 66 is provided with a third switch SW3 made of an n-channel FET or the like. The energization line 68 connected to the positive terminal of the sub battery 22 is connected to the connection point 63. Furthermore, the energization line 69 connected to the negative terminal of the sub-battery 22 is grounded. In this way, the sub-battery 22 is connected in parallel to the main battery 20 and the alternator 18. The illustrated electrical component 26 includes a starter motor 17.

  In the vehicle power supply device 60 having such a configuration, the main battery 20 and the alternator 18 can be connected in series. Thereby, the main battery 20 can be deeply discharged without being restricted by the lower limit voltage of the sub battery 22 or the electrical component 26. That is, the power generation voltage of the alternator 18 is raised in accordance with the voltage drop of the main battery 20 under the state where the switches SW1 and SW3 are switched to the open state and the switch SW2 is switched to the connected state. Thereby, even when the main battery 20 is deeply discharged, the applied voltage to the sub-battery 22 and the electrical component 26 can be maintained at the lower limit voltage or more. Therefore, the storage capacity of the main battery 20 can be fully utilized, and the storage capacity usable in the vehicle power supply device 60 can be increased.

  In such a vehicle power supply device 60 as well, it is necessary to grasp the charge / discharge current of the main battery 20 and the generated current of the alternator 18. However, assembling the current sensor to both the alternator 18 and the main battery 20 has been a factor in increasing the cost of the vehicle power supply device 60. Therefore, the control unit 70 of the vehicle power supply device 60 estimates the power generation current of the alternator 18 as follows in order to reduce the current sensors provided in the alternator 18 so far.

Hereinafter, the estimation control of the generated current executed by the control unit 70 will be described. FIG. 7 is a schematic diagram showing the vehicle power supply device 60. As shown in FIG. 7, the vehicle power supply device 60 is provided with a voltage sensor 41 that detects the voltage V ₁ at the plus terminal of the alternator 18. The vehicle power supply device 60 is provided with a voltage sensor 42 that detects the voltage V ₂ at the connection point 63. Further, the vehicle power supply device 60 is provided with a current sensor 40 as current detection means for detecting the current value of the energization line 64.

First, the control unit 70 connects the switches SW1 and SW3 and opens the switch SW2. As a result, the generated current I ₁ of the alternator 18 is guided toward the main battery 20, so that the generated current I ₁ and the charge / discharge current I ₂ are substantially matched. As indicated by the broken arrow, the generated current I ₁ is also guided to the sub battery 22 and the electrical component 26 via the connection point 63, but the supply current to the sub battery 22 and the electrical component 26 is the main battery. Compared to 20 charge / discharge current I ₂ , it is significantly smaller. That is, since the main battery 20 is a rocking chair type power storage unit with a small charging resistance, a large amount of current is supplied to the main battery 20.

Then, the control unit 70 functioning as a voltage detection means is based on the voltage V _{1 at} the plus terminal of the alternator 18 detected by the voltage sensor 41 and the voltage V ₂ at the connection point 63 detected by the voltage sensor 42. A voltage drop value Vd (= V ₁ −V ₂ ) of the energization line 61 is calculated. Then, the control unit 70 that functions as a resistance calculation means, based on the charging and discharging current (current value) voltage drop value Vd and the calculated I ₂ from the current sensor 40, the current-carrying line 61 in accordance with the following equation (7) calculating the wiring resistance value _{R 1.} Needless to say, the charge / discharge current I ₂ from the current sensor 40, the voltage V ₁ from the voltage sensor 41, and the voltage V ₂ from the voltage sensor 42 are detected values obtained at the same timing.
R ₁ = Vd / I ₂ (7)

As described above, when the wiring resistance value R ₁ of the energization line 61 is calculated, the control unit 70 stores the wiring resistance value R ₁ as data used when calculating the current. Then, the control unit 70 functioning as current estimation means can estimate the generated current I ₁ according to the following equation (2) by obtaining the voltage drop value Vd of the energization line 61. Note that the wiring resistance value R ₁ is periodically calculated and updated because it fluctuates due to aging and temperature environment.
I ₁ = Vd / R ₁ (8)

As described so far, the generated current I ₁ and the charge / discharge current I ₂ can be substantially matched, and therefore the wiring resistance value of the energization line 61 using the charge / discharge current I ₂ detected by the current sensor 40. R ₁ can be obtained. As a result, it is possible to estimate the generated current I ₁ only by detecting the voltage drop value Vd. Therefore, the number of current sensors on the alternator 18 side can be reduced, and the cost of the vehicle power supply device 60 can be reduced. Moreover, because adopting the small rocking chair type power storage unit of the charging resistor to the main battery 20, it is possible to increase significantly the generated current I ₁ of the alternator 18. Thus, since the generated current I ₁ can be increased (for example, 200 A), the voltage drop value Vd can be increased to accurately calculate the wiring resistance value R ₁ . Thereby, it becomes possible to accurately estimate the generated current I _1. Further, by reducing the number of current sensors on the alternator 18 side, it is possible to achieve downsizing of the vehicle power supply device 60. By mounting such a small vehicle power supply device 60 in the engine room, it is possible to improve the collision safety performance and the pedestrian protection performance. Furthermore, by reducing the number of current sensors on the alternator 18 side, the reliability of the vehicle power supply device 60 can be improved.

In the above description, the current sensor 40 is provided in the energization line 64 on the main battery 20 side. However, the present invention is not limited to this, and the current sensor 40 may be provided in the energization line 61 on the alternator 18 side. In this case, the voltage sensor 41 that has detected the voltage at the positive terminal of the alternator 18 is reduced, and a voltage sensor that detects the voltage at the positive terminal of the main battery 20 is added. Then, the control unit 70 calculates the voltage drop value of the energization line 64 based on the voltage from each voltage sensor. Further, the control unit 70 calculates the wiring resistance value of the energization line 64 based on the generated current I ₁ from the current sensor 40 and the calculated voltage drop value of the energization line 64. As described above, since the wiring resistance value of the energization line 64 is obtained, the control unit 70 can estimate the charge / discharge current I ₂ only by detecting the voltage drop value of the energization line 31.

  In the above description, the current sensor 40 is provided in the energization line 64 on the main battery 20 side or the energization line 61 on the alternator 18 side, but the present invention is not limited to this. The number of sensors 40 may be reduced. Here, FIG. 8 is a schematic view showing another vehicle power supply device 80. 8, parts that are the same as the parts shown in FIG. 7 are given the same reference numerals, and descriptions thereof are omitted.

As shown in FIG. 8, the vehicle power supply device 80 is provided with a voltage sensor 51 that detects the voltage V <b> 3 of the positive terminal of the main battery 20. The alternator 18 incorporates a regulator 52 as a protection circuit, and the regulator 52 limits the generated current I ₁ of the alternator 18 to a predetermined upper limit current value I _max (for example, 200 A) or less. In order to estimate the generated current I ₁ and the charge / discharge current I ₂ of the vehicle power supply device 80 as described above, the control unit 81 executes the estimation control of the generated current I ₁ and the charge / discharge current I ₂ as follows.

First, the control unit 81 connects the switches SW1 and SW3 and opens the switch SW2. As a result, the generated current I ₁ of the alternator 18 is guided toward the main battery 20, so that the generated current I ₁ and the charge / discharge current I ₂ are substantially matched. In this case, as the generated current of the alternator 18 reaches the upper limit current value I _max, the power generation voltage of the alternator 18 is raised to the upper limit voltage. That is, the generated current I ₁ and the charge / discharge current I ₂ are in a state that matches the upper limit current value I _max .

The control unit 81 functioning as the first voltage detecting means is based on the voltage V _{1 at} the plus terminal of the alternator 18 detected by the voltage sensor 41 and the voltage V ₂ at the connection point 63 detected by the voltage sensor 42. Thus, the first voltage drop value Vd ₁ (= V ₁ −V ₂₎ of the energization line 61 is calculated. Similarly, the control unit 81 functioning as the second voltage detection means includes the voltage V ₂ at the connection point 63 detected by the voltage sensor 42, and the voltage V _{3 at} the positive terminal of the main battery 20 detected by the voltage sensor 51. Based on the above, the second voltage drop value Vd ₂ (= V ₂ −V ₃ ) of the energization line 64 is calculated.

Next, the control unit 81 functioning as the first resistance calculating means, based on the upper limit current value I _max and the calculated voltage drop value Vd ₁ , according to the following formula (9), the first wiring resistance value R of the energization line 61. ₁ is calculated. Similarly, the control unit 81 functioning as the second resistance calculating means, based on the upper limit current value I _max and the calculated voltage drop value Vd ₂ , the second wiring resistance value of the energization line 64 according to the following formula (10). to calculate the R _2.
R ₁ = Vd ₁ / I _max (9)
R ₂ = Vd ₂ / I _max (10)

As described above, when the wiring resistance value R ₁ of the energization line 61 is calculated, the control unit 81 stores the wiring resistance value R ₁ as data used when calculating the current. Then, the control unit 81 functioning as the first current estimating means can estimate the generated current I ₁ according to the following equation (11) by obtaining the voltage drop value Vd ₁ of the energization line 61. Similarly, the wiring resistance value R ₂ of the current-carrying line 64 is calculated, the control unit 81 stores the wiring resistance value R ₂ as data used during the current calculation. Then, the control unit 81 functioning as the second current estimating means can estimate the charge / discharge current I ₂ according to the following equation (12) by obtaining the voltage drop value Vd ₂ of the energization line 64. Since the wiring resistance values R ₁ and R ₂ fluctuate due to secular change and temperature environment, the wiring resistance values R ₁ and R ₂ are periodically calculated and updated.
I ₁ = Vd ₁ / R ₁ (11)
I ₂ = Vd ₂ / R ₂ (12)

As has been described, can be used the upper limit current value I _max is limited by the regulator 52 of the alternator 18, obtains the wiring resistance value R ₂ of the wiring resistance value R ₁ and the current-carrying line 64 conducting line 61 It becomes. As a result, it is possible to estimate the generated current I ₁ only by detecting the voltage drop value Vd ₁ , so that it is possible to reduce the current sensor on the alternator 18 side. Furthermore, since the charge / discharge current I ₂ can be estimated only by detecting the voltage drop value Vd ₂ , the current sensor on the main battery 20 side can be reduced. Thus, since two current sensors can be reduced, it is possible to achieve a significant cost reduction of the vehicle power supply device 80. Moreover, because adopting the small rocking chair type power storage unit of the charging resistor to the main battery 20, it becomes possible to increase the generated current I ₁ of the alternator 18 to the upper limit current value I _max. Thus, since the generated current I ₁ can be raised to the upper limit current value I _max, it is possible to accurately calculate the wiring resistance values R ₁ and R ₂ by enlarging the voltage drop values Vd ₁ and Vd _2. Become. Thus, the generated current I ₁ and discharge current I ₂ becomes possible to accurately estimate. Further, by reducing the two current sensors, it is possible to achieve downsizing of the vehicle power supply device 80. By mounting such a small vehicle power supply device 80 in the engine room, it is possible to improve the collision safety performance and the pedestrian protection performance. Furthermore, the reliability of the vehicle power supply device 80 can be improved by reducing the two current sensors.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the illustrated case, the present invention is applied to the vehicle power supply devices 10, 50, 60, and 80 of the vehicle 11 having only the engine 12 as a power source. However, the present invention is not limited to this, and the power source The present invention may be applied to a vehicle power supply device for a hybrid vehicle including the engine 12 and an electric motor. The illustrated vehicle power supply device 10, 50, 60, 80 includes a main battery 20 and a sub battery 22. However, the present invention is not limited to this, and the vehicle power supply device that does not include the sub battery 22 is used. The present invention may be applied to this.

  In the above description, the alternator 18 and the starter motor 17 are provided separately. However, an electric motor having the functions of the alternator 18 and the starter motor 17 may be provided. Furthermore, in the above description, the allowable voltage range of the first power supply system 21 is set to about 12 to 18 V, but is not limited to this voltage range. Similarly, the allowable voltage range of the second power supply system 27 is set to about 12 to 15 V, but is not limited to this voltage range.

10 Vehicle Power Supply 18 Alternator (generator)
20 Main battery (power storage unit)
23 Headlight (electric load)
24 Ignition coil (electric load)
25 Electronic control unit (electric load)
26 Electrical components (electric load)
30 Energizing line (first wiring)
31 Energizing line (second wiring)
32 Power line (third wiring)
33 Connection point 34 Separation switch 35 Control unit (voltage detection means, resistance calculation means, current estimation means)
40 Current sensor (current detection means)
60 Power supply device 61 for vehicle Current line (first wiring)
62 Power line (third wiring)
63 Connection point 64 Power line (second wiring)
70 Control unit (voltage detection means, resistance calculation means, current estimation means)
I ₁ Generated current (current value)
I ₂ charge / discharge current (current value)
I _max upper limit current value R ₁ wiring resistance value Vd voltage drop value

Claims (2)

A power supply device for a vehicle comprising a generator connected via a connection point, a first power storage unit and an electric load,
A first wiring connecting the connection point and the generator;
A second wiring connecting the connection point and the first power storage unit;
A third wiring connecting the connection point and the electrical load;
Current detecting means for detecting a current value of the first wiring,
Voltage detecting means for detecting a voltage drop value before Symbol second wiring,
Based on the said voltage drop value and the current value, the resistance calculation means for calculating a wiring resistance value before Symbol second wiring,
Current estimating means the basis voltage drop value and to said wiring resistance value, to estimate the current value of the detected have such pre-gastric Symbol second wiring by said current detecting means,
A separation switch provided in the third wiring and switched to an open state for disconnecting the electrical load from the generator and the first power storage unit;
A second power storage unit connected to the third wiring between the electric load and the separation switch,
The current detection means detects the current value used for calculation of the wiring resistance value under a state where the separation switch is switched to an open state,
The vehicle power supply apparatus , wherein the voltage detection means detects the voltage drop value used for calculating the wiring resistance value in a state where the separation switch is switched to an open state . A power supply device for a vehicle comprising a generator connected via a connection point, a first power storage unit and an electric load,
A first wiring connecting the connection point and the generator;
A second wiring connecting the connection point and the first power storage unit;
A third wiring connecting the connection point and the electrical load;
Current detecting means for detecting a current value before Symbol second wiring,
Voltage detecting means for detecting a voltage drop value of the first wiring,
Based on the said voltage drop value and the current value, the resistance calculation means for calculating a wiring resistance value of the first wiring,
Current estimating means for estimating a current value of the basis voltage drop between the said wiring resistance value, not detected by said current detecting means and the first wiring,
A separation switch provided in the third wiring and switched to an open state for disconnecting the electrical load from the generator and the first power storage unit;
A second power storage unit connected to the third wiring between the electric load and the separation switch,
The current detection means detects the current value used for calculation of the wiring resistance value under a state where the separation switch is switched to an open state,
The vehicle power supply apparatus , wherein the voltage detection means detects the voltage drop value used for calculating the wiring resistance value in a state where the separation switch is switched to an open state .

Images