JP2007210554A - Vehicle power supply device and battery condition detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a battery condition of a vehicle in an AC impedance method, without mounting an additional AC source to the vehicle. <P>SOLUTION: This vehicle power supply device is provided with a battery 12 connected to an on-vehicle load 60 and with an alternator 34 connected to a drive source of the vehicle. The vehicle power supply device is further provided with a first current passage 50 for rectifying AC current generated by the alternator 34 via a rectifying circuit 36 and guiding the current to the battery 12 and with a second current passage 52 for guiding the AC current generated by the alternator 34 to the battery 12 without making the current go through the rectifying circuit 36. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle power supply device including a battery and an alternator, and a battery state detection device used in the power supply device.

Conventionally, a method for measuring the internal impedance of a lead storage battery using an AC impedance method or a method for determining deterioration of a lead storage battery is known (see, for example, Patent Document 1).
JP 2005-037380 A

  However, in order to detect the state of the battery of the vehicle in the vehicle usage state using the AC impedance method, an AC generation source must be newly installed in the vehicle, which is problematic from the viewpoint of layout and cost.

  Therefore, an object of the present invention is to provide a vehicle power supply device and a battery state detection device that can detect the state of a battery of a vehicle by an AC impedance method without newly installing an AC generation source in the vehicle.

To achieve the above object, according to a first aspect of the present invention, there is provided a vehicle power supply device including a battery connected to a vehicle-mounted load and an alternator connected to a drive source of the vehicle.
A first current path that rectifies the alternating current generated by the alternator through a rectifier circuit and guides it to the battery;
And a second path for guiding the alternating current generated by the alternator to the battery without passing through the rectifier circuit.

According to a second aspect of the present invention, in the vehicle power supply device according to the first aspect,
The second path is provided with switching means for switching a conduction / non-conduction state between the alternator and the battery.

3rd invention is the vehicle power supply device which concerns on 1st or 2nd invention,
A battery state detecting means for detecting the state of the battery is provided based on the impedance characteristic of the battery when the alternating current is guided through the second path.

A fourth invention is a vehicle power supply device according to the third invention,
The battery state detection means calculates the internal resistance of the battery by an AC impedance method.

5th invention is the battery state detection apparatus which detects the state of a vehicle-mounted battery,
Based on the AC output waveform generated by the alternator, an AC waveform application path for applying an AC waveform to the battery is provided,
The battery state is detected based on the impedance characteristics of the battery when an AC waveform is applied to the battery.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle power supply device and battery state detection apparatus which can detect the state of the battery of a vehicle by alternating current impedance method, without mounting an alternating current generation source in a vehicle newly are obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a system configuration diagram showing Embodiment 1 of a vehicle power supply device 10 according to the present invention. The vehicle power supply device 10 of this embodiment includes a battery 12. The battery 12 is a lead battery (main battery) having a voltage of about 12V. However, as the battery 12, other batteries such as a capacitive load such as a lithium ion battery, a fuel cell, and an electric double layer capacitor may be used.

  The battery 12 is connected to an AC generator 34 (hereinafter referred to as “alternator 34”) that generates power by rotating the engine. The amount of power generated by the alternator 34 is controlled according to the traveling state of the vehicle, for example, by an EFI / ECU that controls the engine. For example, when the vehicle is traveling normally or the engine is idling, the power generation voltage of the alternator 34 is adjusted to a value (for example, 14 V) that does not cause the battery 12 to discharge. Further, when the vehicle is decelerated (when the regenerative brake is activated), the power generation voltage of the alternator 34 is adjusted to a larger value than during steady running or idle running. Further, during vehicle acceleration, the power generation voltage of the alternator 34 is adjusted so that the integrated value of the input / output current of the battery 12 approaches the target value. The present invention does not specify the power generation control of the alternator 34, and can be applied to any form of power generation control.

  As shown in FIG. 1, the alternator 34 is configured to generate, for example, a three-phase alternating current. Specifically, as shown in FIG. 1, the alternator 34 has three coils 35a, 35b, and 35c arranged at intervals of 120 degrees, and generates a three-phase alternating current synchronized with the rotation of the engine. The three-phase alternating current is output as a direct current waveform to the direct current waveform output terminal 34b by a three-phase full-wave rectification action by a rectifier circuit (rectifier) 36 composed of six diodes. In the example shown in FIG. 1, a rectifier circuit 36 having a built-in filter for removing a noise component or the like of a direct current is provided in the previous stage of the direct current waveform output terminal 34b. The direct current waveform thus obtained is supplied to the battery 12 and various loads 60 through the direct current supply line 50.

  The DC current supply line 50 connects between the DC waveform output terminal (plus terminal) 34b of the alternator 34 and each terminal (plus terminal) of the battery 12 and various loads 60. The branch line 50a to the battery 12 is connected to the branch line 50a. A control relay 70B is provided. The various loads 60 include starters, transmissions, audio devices, air conditioners, headlamps, fog lamps, cornering signal lamps, corner lamps, and other lamps, car navigation, meters, defoggers, wipers, actuators that drive power windows, and the like. And various auxiliary machines (vehicle equipment). The wiring 53 connects between a battery state detection ECU 14 described later and an input terminal 34c of the alternator 34, and is connected to the alternator field coil 35d. The battery state detection ECU 14 varies the alternator output current by supplying the alternator field drive signal to the alternator field coil 35d via the wiring 53.

  As shown in FIG. 1, the alternator 34 of the present embodiment includes an AC waveform output terminal 34a that outputs an AC current in addition to the DC waveform output terminal 34b. For example, as shown in FIG. 1, the AC waveform output terminal 34 a is a terminal that takes out a three-phase AC generated by the three coils 35 a, 35 b, and 35 c from the connection portion of the two coils 35 a and 35 b. The alternating current waveform of the alternator 34 output from the alternating current waveform output terminal 34 a is supplied to the battery 12 via the alternating current supply line 52. Specifically, as shown in FIG. 1, the AC current supply line 52 is connected to an AC waveform output terminal 34a and a terminal (plus terminal) of the battery 12 via a capacitor 52a and a control relay 70A for removing a DC component. ). The alternating current supply line 52 is connected between the battery 12 and the control relay 70A in the direct current supply line 50 (branch line 50a). Therefore, in this embodiment, the battery 12 is configured so that a DC waveform or an AC waveform can be selectively applied to the battery 12 by controlling the two control relays 70A and 70B.

  Normally, the control relay 70A is in an off state, the control relay 70B is in an on state, and a direct current waveform is applied to the battery 12. In this state, the battery 12 can be charged by the electric power generated by the alternator 34, and various loads 60 can be operated by the electric power taken out from the battery 12.

  The vehicle power supply device 10 includes an electronic control unit 14 (hereinafter referred to as “battery state detection ECU 14”) that realizes a function of detecting the state of the battery 12. The electronic control unit 14 is configured around a CPU, and includes a ROM, a RAM, an I / O, and the like in which a program and data for realizing a battery detection function described in detail below are stored. The function of the battery state detection ECU 14 may be realized by another ECU (typically, an EFI / ECU).

  The battery state detection ECU 14 receives the battery current, the battery voltage, and the battery temperature. The battery current is detected by the current sensor 16. The current sensor 16 is attached to a positive terminal of the battery 12, for example, detects the charge / discharge current amount of the battery 12 at a predetermined sampling period, and supplies the signal to the battery state detection ECU 14. The current sensor 16 may convert, for example, a change amount of magnetic flux density generated in the core portion by the charge / discharge current amount into a voltage using a Hall IC, and output the voltage to the battery state detection ECU 14. The battery voltage is detected by a voltage sensor. The voltage sensor is attached to the plus terminal of the battery 12, detects the terminal voltage of the battery 12 at a predetermined sampling period, and supplies the signal to the battery state detection ECU 14.

  The battery temperature is detected by the battery temperature sensor 18. The battery temperature sensor 18 has a sensor unit made up of a thermistor, and is attached to, for example, the insulator side surface of the battery 12. To supply.

  The battery state detection ECU 14 detects the state of the battery 12 based on the battery current, the battery voltage, and the battery temperature that are thus input at predetermined intervals. The state of the battery 12 detected by the battery state detection ECU 14 can be used for determining the output timing of a warning display that prompts replacement of the battery 12, the control of the alternator 34, and the like. The state of the battery 12 includes the remaining capacity and the deterioration level of the battery 12, and in order to determine the state of the battery 12 with high accuracy, the internal resistance of the battery 12 needs to be detected with high accuracy.

  As a method for calculating the internal resistance of a battery, for example, as disclosed in Japanese Patent Application Laid-Open No. 2005-037380, a calculation method using an AC impedance method is known. This calculation method analyzes a response current (phase difference between an input signal and an output signal) by giving a minute sine wave voltage amplitude to a battery. Specifically, the measured impedance is plotted on a complex plane, and the internal resistance of the battery is obtained based on the diameter of the semicircular portion appearing in the Cole-Cole plot (impedance characteristic) obtained thereby.

  Although this AC impedance method is suitable in that the internal resistance of a general battery can be detected with high accuracy, it is not used as a method for calculating the battery 12 for a vehicle. This is because, in a vehicle, it is common to operate various loads 60 using a direct current, and therefore, there is no AC power supply in the vehicle. Therefore, conventionally, as a method for calculating the internal resistance of the vehicle battery, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-31170, there is a calculation method based on a direct current (charge / discharge current) flowing through the battery 12. It is common.

  In contrast, in this embodiment, as described below with reference to FIG. 2, the internal resistance of the battery 12 can be calculated by the AC impedance method by using the AC waveform of the alternator 34. To do.

  FIG. 2 is a flowchart showing the flow of the internal resistance detection process executed by the battery state detection ECU 14 of the present embodiment.

  In step 100, it is determined whether a condition for starting the internal resistance detection process is satisfied. For example, the start condition may be satisfied when the battery temperature is −10 ° C. or more and a predetermined time has elapsed after the ignition switch is turned on. Alternatively, the internal resistance detection process may be executed when a predetermined condition is satisfied while the vehicle is traveling (for example, when fully charged) or when the ignition switch is turned off. In addition, when it is executed when the ignition switch is turned off, the engine is continuously operated for a predetermined time.

  In step 110, the battery state detection ECU 14 forms a state in which the AC waveform from the alternator 34 is applied to the battery 12 in order to calculate the internal resistance of the battery 12 by the AC impedance method. Specifically, the battery state detection ECU 14 switches off the control relay 70B to cut off the direct current supply state to the battery 12, and switches on the control relay 70A to form the alternating current supply state to the battery 12. To do. In addition, since the control relay 70B is set to the branch line 50a, the power supply to the various loads 60 is not interrupted even when the control relay 70B is switched off. The state in which the AC waveform from the alternator 34 is applied to the battery 12 is maintained for a predetermined time until necessary data is obtained.

  In step 120, the battery state detection ECU 14 detects the internal resistance of the battery 12 by the AC impedance method based on the data acquired in step 110. In this example, the battery state detection ECU 14 has the impedance characteristic of the battery 12 derived based on the data acquired in step 110 and the same impedance measured when the battery 12 is in a new state (for example, at the time of vehicle shipment). The deterioration level of the battery 12 is estimated by comparing with the characteristics. When the deterioration level of the battery 12 becomes equal to or higher than a predetermined level, the battery state detection ECU 14 displays a warning for prompting the user to replace the battery 12 in the meter, or the low priority among the various loads 60. Necessary measures are taken such as limiting the operation with respect to a load (for example, a load not related to the running performance of the vehicle but related to the comfort of the vehicle, such as a seat heater).

  In step 130, the battery state detection ECU 14 cancels the state in which the AC waveform is applied to the battery 12 and returns to the normal state in which the DC waveform is applied to the battery 12 in order to end the measurement of the internal resistance of the battery 12. Let Specifically, the battery state detection ECU 14 switches off the control relay 70A to cut off the alternating current and switches on the control relay 70B.

  As described above, according to the present embodiment, by using the existing alternator 34 mounted on the vehicle, a state where an AC waveform is applied to the battery 12 is formed without setting a new AC power source. As a result, based on the impedance characteristics of the battery 12 when an AC waveform is applied to the battery 12, the internal resistance of the battery 12 can be calculated with high accuracy by the AC impedance method.

  FIG. 3 is a system configuration diagram illustrating the vehicle power supply device according to the second embodiment. Hereinafter, the same configurations as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The vehicle power supply device 10 of the present embodiment is mainly different from the first embodiment described above in that the control relay 70B is eliminated.

  Specifically, as shown in FIG. 3, the DC current supply line 50 is connected between the DC waveform output terminal (plus terminal) 34 b of the alternator 34 and each terminal (plus terminal) of the battery 12 and various loads 60. Connecting. As shown in FIG. 3, the AC current supply line 52 includes an AC waveform output terminal 34a and a terminal of the battery 12 through a capacitor 52a and a control relay 70A for removing a DC component, as shown in FIG. Connect to (plus terminal). Specifically, the alternating current supply line 52 connects the alternating current waveform output terminal 34a to the direct current supply line 50 via the capacitor 52a and the control relay 70A. Therefore, in the present embodiment, the battery 12 is configured to be able to selectively apply a DC waveform or an AC waveform (an AC waveform superimposed on the DC waveform) by controlling the control relay 70A.

  Therefore, also in the present embodiment, the internal resistance of the battery 12 can be calculated by the alternating current impedance method by using the alternating current waveform of the alternator 34 as in the first embodiment.

  FIG. 4 is a flowchart showing the flow of the internal resistance detection process executed by the battery state detection ECU 14 of the present embodiment.

  In step 200, it is determined whether or not a condition for starting the internal resistance detection process is satisfied.

  In step 210, the battery state detection ECU 14 forms a state in which the AC waveform from the alternator 34 is applied to the battery 12 so as to calculate the internal resistance of the battery 12 by the AC impedance method. Specifically, the battery state detection ECU 14 switches the control relay 70A from off to on. Thereby, the AC waveform superimposed on the DC waveform is applied to the battery 12. When the control relay 70A is switched on, the AC waveform superimposed on the DC waveform is also applied to the various loads 60. However, the filters 60 (that is, the AC waveform is removed). Thus, current is applied via a filter that extracts only the DC waveform), so that the operation of the various loads 60 is not adversely affected. Alternatively, the operation of the various loads 60 can be prevented from being adversely affected by adjusting the drive current of the alternator field coil 35d with the AC superimposed waveform. The state in which the AC waveform from the alternator 34 is applied to the battery 12 is maintained for a predetermined time until necessary data is obtained.

  In step 220, the battery state detection ECU 14 detects the internal resistance of the battery 12 by the AC impedance method based on the data acquired in step 210. In this example, the battery state detection ECU 14 is acquired in the same manner when the impedance characteristic of the battery 12 derived based on the data acquired in the above step 210 and when the battery 12 is in a new state (for example, at the time of vehicle shipment). The deterioration level of the battery 12 is estimated by comparing with the same impedance characteristic.

  In step 230, the battery state detection ECU 14 switches off the control relay 70A to end the measurement of the internal resistance of the battery 12. As a result, the state in which the AC waveform is applied to the battery 12 is released, and the normal state in which the DC waveform is applied to the battery 12 is restored.

  As described above, according to the present embodiment, similarly to the above-described first embodiment, the AC waveform is applied to the battery 12 without setting a new AC power source by using the existing alternator 34 mounted on the vehicle. As a result, based on the impedance characteristics of the battery 12 when an AC waveform is applied to the battery 12, the internal resistance of the battery 12 is calculated with high accuracy by the AC impedance method. be able to. Further, the cost can be reduced by omitting the control relay 70B.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, the embodiment described above relates to a power supply system that supplies electric power to various loads 60 from a single battery (lead battery 12), but the scope of application of the present invention is limited to this type of single power supply system. For example, the present invention is also applicable to a dual power supply system in which two batteries (for example, a lead battery and a lithium ion battery) having different rated voltages are set via a DC / DC converter. In this case, an alternating current waveform from the alternator 34 can be applied to the battery on the side where the alternator 34 exists via a DC / DC converter by the same circuit as described above. Further, an alternating current waveform from the alternator 34 is set by setting a separate and independent alternating current supply line not via the DC / DC converter for the battery existing on the opposite side of the alternator 34 via the DC / DC converter. Can be applied.

  In the above-described embodiment, the control relay is used as the switching means. However, a semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) may be used.

1 is a system configuration diagram showing an embodiment of a vehicle power supply device 10 according to the present invention. 3 is a flowchart illustrating a flow of an internal resistance detection process executed by a battery state detection ECU 14 according to the first embodiment. FIG. 4 is a system configuration diagram illustrating a vehicle power supply device according to a second embodiment. It is a flowchart which shows the flow of the internal resistance detection process performed by battery state detection ECU14 of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle power supply device 12 Lead battery 14 Battery state detection ECU
16 Current sensor 18 Battery temperature sensor 34 Alternator 36 Rectifier circuit 50 DC current path 52 AC current supply line 60 Various loads 70A Control relay 70B Control relay

Claims (5)

In a vehicle power supply device comprising a battery connected to an in-vehicle load and an alternator connected to a drive source of the vehicle,
A first current path that rectifies the alternating current generated by the alternator through a rectifier circuit and guides it to the battery;
A vehicle power supply device comprising: a second path that guides an alternating current generated by the alternator to a battery without passing through a rectifier circuit.   The vehicle power supply device according to claim 1, comprising switching means for switching a conduction / non-conduction state between the alternator and the battery in the second path.   The vehicle power supply device according to claim 1, further comprising a battery state detection unit that detects a state of the battery based on an impedance characteristic of the battery when the alternating current is guided through the second path.   The vehicle power supply device according to claim 3, wherein the battery state detection means calculates the internal resistance of the battery by an AC impedance method. In the battery state detection device that detects the state of the in-vehicle battery,
Based on the AC output waveform generated by the alternator, an AC waveform application path for applying an AC waveform to the battery is provided,
A battery state detection device that detects a state of a battery based on impedance characteristics of the battery when an AC waveform is applied to the battery.

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