JP2008067421A - Suppliable current prediction device and power supply controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suppliable current prediction device which enhances prediction precision of the value of a current suppliable through a battery. <P>SOLUTION: The suppliable current prediction device calculates the voltage/current characteristics of a battery 10 based on sampled voltage value and current value of the battery 10 connected to electric loads 41-44, and predicts the value of a current suppliable through the battery 10 based on the calculated voltage/current characteristics. The suppliable current prediction device comprises a reference table (20) storing the number of revolutions of an engine 61, and the maximum output current value of an onboard generator 51 corresponding to the temperature of the onboard generator 51 interlocked with the engine 61, a means (24) for acquiring the maximum output current value with reference to the reference table (20) based on the number of revolutions detected by a number-of-revolutions detector 62, and the temperature detected by a temperature detector 51, and a means 24 for predicting a suppliable current value based on the maximum output current value and the voltage/current characteristics thus acquired. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a suppliable current prediction device that predicts a suppliable current value based on a voltage value and a current value of a vehicle battery connected to an electric load, and a suppliable current predicted by the suppliable current prediction device. The present invention relates to a power supply control device that controls electric power supplied to an electric load through a battery based on a value.

  Electric loads mounted on vehicles tend to increase year by year. Large-capacity electric loads such as wind defoggers and seat heaters for cold regions are adopted, and equipment that has been operated with hydraulic pressure or engine power is electrified to improve control performance and efficiency. It is out. Electric loads that require high reliability such as electric brakes and electric power steering devices (EPS) have also been adopted.

In response to such an increase in electric load, it is necessary to increase the capacity of the on-vehicle generator and the battery, but there are limitations in terms of mounting conditions and cost. For this reason, when an excessive load power is generated, the voltage of the power supply system may greatly decrease due to the discharge from the battery. Further, when the battery is over-discharged to a voltage lower than the end-of-discharge voltage, the deterioration of the electrode progresses and the life may be shortened.
Patent Document 1 discloses a power supply device that detects a state of a battery, predicts a voltage drop when a large current flows, and restricts a load according to its importance when the voltage drops below a reference value.
JP 2004-194364 A JP 2000-326805 A

  In the power supply device disclosed in Patent Document 1, the maximum output current of the generator is taken into account when detecting the state of the battery and predicting the voltage drop when a large current flows. However, it is only described that "the maximum output of the generator is generally determined by the rotational speed, and the maximum output current of the generator is obtained by inputting the rotational speed information" (paragraph [0028]). Because the factor that determines the maximum output current of the generator is limited to the rotational speed, there is a problem that the prediction of the voltage drop becomes inaccurate. Also, no consideration is given to a load whose importance changes depending on the traveling speed of the vehicle.

  The present invention has been made in view of the above-described circumstances. In the first and second inventions, an object of the present invention is to provide a supplyable current prediction apparatus that improves the prediction accuracy of a supplyable current value through a battery.

  In the third and fifth inventions, an object is to provide a power supply control device for controlling the power supplied to the electric load through the battery based on the suppliable current value predicted by the suppliable current predicting device according to the first or second invention. And

  In the fourth aspect of the invention, the power supplied to the electric load through the battery is determined based on the supplyable current value predicted by the supplyable current prediction apparatus according to the first or second aspect of the invention and the importance of the electric load that changes depending on the traveling speed of the vehicle. It is an object of the present invention to provide a power supply control device that performs control based on the above.

  A suppliable current prediction apparatus according to a first aspect of the invention is based on means for sampling a voltage value and a current value of a battery for a vehicle to which a plurality of electric loads are connected, and the voltage value and current value sampled by the means. Means for calculating a voltage / current characteristic of a battery, and a supplyable current prediction device for predicting a supplyable current value that can be supplied through the battery based on the voltage / current characteristic calculated by the means, wherein the number of revolutions of the engine A rotational speed detector that detects the temperature, a temperature detector that detects the temperature of the in-vehicle generator linked to the engine, and a reference that stores the maximum output current value of the in-vehicle generator according to the rotational speed and temperature A table, and means for obtaining a maximum output current value with reference to the reference table based on the rotation speed detected by the rotation speed detector and the temperature detected by the temperature detector; Maximum output current value which the unit has acquired, and based on the voltage-current characteristic, characterized by comprising a prediction means for predicting a suppliable current value.

  In this suppliable current prediction device, the voltage value and current value of a battery for a vehicle to which a plurality of electric loads are connected are sampled, and based on the sampled voltage value and current value, the voltage-current characteristic of the battery is calculated, Based on the calculated voltage-current characteristics, a supplyable current value that can be supplied through the battery is predicted. The rotational speed detector detects the rotational speed of the engine, and the temperature detector detects the temperature of the on-vehicle generator linked to the engine. The reference table stores the maximum output current value of the on-vehicle generator according to the engine speed and the temperature of the on-vehicle generator, and the means for obtaining the rotation number detected by the rotation detector and the temperature detector Based on the detected temperature, the maximum output current value is acquired by referring to the reference table. The predicting means predicts a suppliable current value based on the acquired maximum output current value and voltage-current characteristics.

  In the suppliable current predicting apparatus according to a second aspect of the present invention, the predicting means includes a lower limit voltage value of the battery determined based on a voltage value required by the electric load and a voltage-current characteristic of the battery. A current value when the voltage value is the lower limit voltage value is calculated, and a suppliable current value is predicted by adding the calculated current value and the maximum output current value.

  In this suppliable current predicting device, the predicting means is configured such that the battery voltage value is the lower limit voltage value based on the lower limit voltage value of the battery determined based on each required voltage value and the calculated voltage-current characteristic. A current value at a certain time is calculated, and a suppliable current value is predicted by adding the calculated current value and the maximum output current value.

  A power supply control device according to a third aspect of the present invention is a power supply control device that controls electric power supplied to a plurality of electric loads through a vehicle battery. Means for determining whether or not the supplyable current value predicted by the current prediction device is smaller than a predetermined current value; and when determining that the means is small, selectively supplying power to the electric load for a predetermined time. And a stop / limit means for stopping or limiting.

  In this power supply control device, power supplied to a plurality of electric loads through a vehicle battery is controlled. It is determined whether or not the suppliable current value predicted by the suppliable current predicting device is smaller than a predetermined current value. When it is determined that the suppliable current value is small, the supply of power to the electric load is selectively stopped or limited for a predetermined time. .

  The power control apparatus according to the fourth aspect of the present invention further comprises means for comparing the rotational speed detected by the rotational speed detector for detecting the rotational speed of the engine with a predetermined rotational speed, wherein the stop / limit means is a comparison of the means. According to a result, it is comprised so that supply of the electric power to the electric load may be selectively stopped or restricted.

  In this power supply control device, the rotational speed detected by the rotational speed detector that detects the rotational speed of the engine is compared with a predetermined rotational speed, and the supply of electric power to the electric load is selectively stopped according to the comparison result. Or restrict.

  According to a fifth aspect of the present invention, there is provided the power supply control device, wherein the rotation speed detector for detecting the rotation speed of the engine detects when the stop / limit means selectively stops or restricts the supply of power to the electric load. Means for determining whether or not the engine is idling based on the determined engine speed, and means for increasing the engine speed by a predetermined amount when it is determined that the engine is idling. It is further provided with the feature.

  In this power supply control device, when the stop / limit means selectively stops or restricts the supply of electric power to the electric load, the means for determining is detected by the engine speed detector that detects the engine speed. Based on the rotational speed, it is determined whether or not the engine is idling. When it is determined that the engine is idling, a means for increasing the engine increases the rotational speed of the engine by a predetermined amount.

  According to the suppliable current predicting apparatus according to the first and second inventions, the maximum output current value is obtained by referring to the reference table based on the rotational speed detected by the rotational speed detector and the temperature detected by the temperature detector. Since the suppliable current value is predicted based on the acquired maximum output current value and voltage-current characteristics, it is possible to realize a suppliable current predicting apparatus that improves the prediction accuracy of the suppliable current value through the battery.

  According to the power supply control device according to the third and fifth inventions, the power supplied to the electric load through the battery is controlled based on the supplyable current value predicted by the supplyable current prediction device according to the first or second invention. A power supply control device can be realized.

  According to the power supply control device of the fourth aspect of the invention, the supply of electric power to the electric load is selectively stopped or restricted according to the comparison result between the engine speed and the predetermined engine speed. A power supply control device that controls the power to be supplied based on the suppliable current value predicted by the suppliable current predicting device according to the first or second invention and the importance of the electric load that changes according to the traveling speed of the vehicle is realized. can do.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a supplyable current prediction apparatus and a power supply control apparatus according to the present invention.
In this power supply control apparatus, an electric load such as an air conditioner (air conditioner) / heater 41, a headlight 42, a fog lamp 43 and a defogger 44 is connected to a battery 10 and an alternator (on-vehicle generator, alternator) via a power supply control ECU 20. ) Power is supplied from 50.

  The battery 10 is a storage battery having two working electrodes, and one terminal is connected to the power supply control ECU 20 and the other terminal is grounded. The alternator 50 charges the battery 10 appropriately in conjunction with the engine 61. Normally, electric power is supplied from the alternator 50 to each electric load, and electric power is supplied from the battery 10 when the engine 61 is stopped or when a large load electric power exceeding the output of the alternator 50 is required.

The engine 61 is provided with a rotation speed detector 62 for detecting the rotation speed. The rotation speed detected by the rotation speed detector 62 is supplied to the power supply control ECU 20 and the engine control unit 60 and used for controlling the engine 61. Is done. Since the alternator 50 rotates in conjunction with the engine 61 and the rotation speeds of the alternator 50 and the engine 61 correspond one-to-one, the rotation speed of the engine 61 given to the power control ECU 20 is the rotation of the alternator 50. Used as a number.
The alternator 50 is provided with a temperature detector 51 for detecting the temperature, and the temperature detected by the temperature detector 51 is given to the power supply control ECU 20.
An instruction signal for increasing or decreasing (recovering) the rotational speed of the engine 61 is given from the power supply control ECU 20 to the engine control unit 60.

The voltage detection unit 21 detects the voltage value Vb between the two electrodes of the battery 10 and supplies it to the power supply control ECU 20.
The current detection unit 22 detects the current value Ib flowing through the battery 10 and provides it to the power supply control ECU 20.
The power supply control ECU 20 corresponds to a power supply control device according to the present invention, and includes a voltage-current characteristic calculation unit 23, a suppliable current prediction unit 24, and a switching unit 25. In the present embodiment, the power supply control ECU 20 includes a suppliable current prediction device including a voltage / current characteristic calculation unit 23 and a suppliable current prediction unit 24.

Here, as shown in FIG. 2, the internal resistance of the battery 10 is Rb, the current flowing out of the battery 10 is Ib, the open voltage when no current flows from the battery 10 is Vbo, and the (output) voltage value of the battery 10 is Vb, the output current of the alternator 50 is Ialt, and the total current (suppliable current) flowing through the electric loads 41, 42,. The output voltage of the alternator 50 is rectified and adjusted to a constant voltage Va.
At this time, the minimum voltage value Vmin (lower limit voltage value) that the battery 10 needs to output is
Vmin <Vb = Vbo-Rb.times.Ib = Vbo-Rb (Iload-Ialt) (1)
∴Iload <(Vbo-Vmin) / Rb + Ialt
<(Vbo-Vmin) / Rb + f (n, t) (2)
Thus, the maximum value of the suppliable current value Iload can be obtained by equation (2).

Here, f (n, t) is the maximum output current value of the alternator 50 determined by the rotational speed n of the alternator 50 and the temperature t.
In addition, the minimum voltage at which all devices in each system of the electrical load can operate is the safety system (airbag, tire pressure sensor, wiper, etc.);
Comfortable system (air conditioner, navigation device, audio device, massage seat, etc.); Ea
Security system (immobilizer, etc.); Ese
Traveling system (electric power steering device, air suspension, etc.); Er
Body system (doors, power windows, sunroofs, etc.); Eb
Then, the voltage value Vmin that the battery 10 needs to output at least is determined by Vmin = Max [Esa, Er] because the safety system and the traveling system cannot be turned off.

The voltage-current characteristic calculation unit 23 samples the voltage value Vb of the battery 10 given from the voltage detection unit 21 and the current value Ib of the battery 10 given from the current detection unit 22, and the sampled voltage value Vb and current value are sampled. Based on Ib, the voltage-current characteristic of the battery 10 as shown in FIG. 5 is calculated. Specifically, the sampled voltage value Vb and current value Ib are statistically processed (here, the least square method), and the voltage-current characteristic is linearly approximated as shown in equation (3), which is a parameter of the approximate expression. The slope Rb (internal resistance) and the intercept Vbo (open voltage) are calculated.
V = -Rb * I + Vbo (3)

The suppliable current predicting unit 24 predicts the suppliable current Iload based on the voltage / current characteristic calculated by the voltage / current characteristic calculating unit 23 using the equation (2).
The switching unit 25 is disposed between the battery 10 and each electric load (air conditioner / heater 41, headlight 42, fog lamp 43, defogger 44, etc.), and each electric load is turned on / off (partial on / off is also performed). It is comprised by each relay device for controlling. Each electric load is supplied with electric power from the battery 10 via the switching unit 25. Note that the configuration of the switching unit 25 is not limited to the relay device, and connection / disconnection of each electric load to the battery 10 may be controlled by communication.

The power supply control ECU 20 is configured by a microcomputer except for the switching unit 25, and the maximum output current value f (n) of the alternator 50 described above is stored in a memory (not shown) as shown in FIG. , T) is stored. The maximum output current value f (n, t) becomes smaller (larger) as the temperature t becomes higher (lower).
The alternator 50 has an external load characteristic as shown in FIG. 7B, and outputs a larger current as the rotational speed is higher. However, the output voltage is adjusted to a substantially constant voltage Va.

Here, each voltage-current characteristic of the battery 10, the alternator 50, and the electric loads 41, 42... (Resistances R of all electric loads connected in parallel) is as shown in FIG. (A) is when the power generation amount of the alternator 50 is small, and (b) is when the power generation amount of the alternator 50 is large.
In FIG. 6, a point P is an equilibrium point between the battery 10 and the electric loads 41, 42... When the alternator 50 is not present, and a point Q is when the battery 10 is not present. , An equilibrium point of the alternator 50 and the electric loads 41, 42. Point S is an equilibrium point of the battery 10 when the actual battery 10, the alternator 50, and the electric loads 41, 42,.

  If the point P indicating the current value actually required by the electric loads 41, 42,... Is on the right side of the point Q indicating the current value supplied by the alternator 50, the battery 10 is supplied with the current supplied by the alternator 50. The shortage (Id) is discharged. If the point P is on the left side of the point Q, the battery 10 is charged with a surplus current (Ic) supplied by the alternator 50.

Hereinafter, the processing procedure of the supplyable current prediction apparatus and the power supply control apparatus having such a configuration will be described with reference to the flowcharts of FIGS.
First, when an ignition key (hereinafter referred to as IG key) is turned on (S1), the power supply control ECU 20 resets the flag F and the parameter k (F = 0, k = 0) (S3). Next, the voltage / current characteristic calculator 23 samples the voltage value Vb and the current value Ib of the battery 10 (S5), and determines whether or not the parameter k is equal to or greater than a predetermined number (N-1) (S7).
If the parameter k is not equal to or greater than the predetermined number (N-1) (S7), the voltage-current characteristic calculation unit 23 adds 1 to the parameter k (S39), and then starts measuring time (S41), and the predetermined time T1. When the time measurement is completed (S43), the time measurement is reset (S45), and the voltage value Vb and the current value Ib are sampled again (S5).

  If the parameter k is equal to or greater than the predetermined number (N-1) (S7), the voltage-current characteristic calculation unit 23 resets the parameter k assuming that the number of samples has reached the predetermined number N (S9). Next, the voltage value Vb and the current value Ib of the battery 10 sampled by the predetermined number N are statistically processed (linear approximation) to calculate an expression Vb = Vbo−Rb Ib indicating the voltage-current characteristics as shown in FIG. Voltage-current characteristics (slope Rb and intercept Vbo) are calculated (S11).

Next, in the power supply control ECU 20, the suppliable current prediction unit 24 acquires the engine speed n and the temperature t of the alternator 50 (S13). Next, referring to a table (FIG. 7A) showing the maximum output current value f (n, t) of the alternator 50, the maximum output current value f (n corresponding to the acquired rotation speed n and temperature t (S13). , T) is acquired (S14).
Next, the suppliable current predictor 24 predicts the maximum value Ip of the suppliable current value Iload based on the known intercept Vbo, voltage value Vmin, slope Rb, and maximum output current value f (n, t). The
Ip = (Vbo-Vmin) / Rb + f (n, t) (2)
(S15).

Next, the suppliable current prediction unit 24 determines whether or not the calculated predicted value Ip (S15) is larger than the predetermined current value Ith (S17). If it is larger, the voltage value Vb and the current value Ib are again set. Sampling is performed (S5). The predetermined current value Ith is a value determined based on the current value of all the electric loads 41, 42... + The inrush current value (such as a built-in motor).
When the suppliable current prediction unit 24 determines that the predicted value Ip is not greater than the predetermined current value Ith (S17), the power supply control ECU 20 causes the switching unit 25 to load the electric load 41 corresponding to the load current (Ith−Ip). After the power switch of 42... Is cut (load control) (S19), the timing is started (S21). The power switch includes a power switch for partially limiting the power supply of the load.

The suppliable current prediction unit 24 compares the rotational speed detected by the rotational speed detector 62 with a predetermined rotational speed when the switching unit 25 cuts off the power switch of the electric loads 41, 42... (S19). Thus, when the vehicle is traveling at a high speed and when the vehicle is traveling at a low speed, the priority for cutting is determined according to the determination result.
For example, the headlight 42 is not included in the operation target of the power switch during high-speed driving (priority is not assigned), but the priority is given to operate the power switch from high to low during low-speed driving. .

The defogger 44 is given a priority for cutting off the power switch regardless of whether the vehicle is traveling at high speed or low speed.
The fog lamp 43 is not included in the operation target of the power switch during high-speed traveling (priority is not assigned), but is given priority for disconnecting the power switch during low-speed traveling.
The air conditioner / heater 41 is given a priority order to turn off the power switch regardless of whether it is traveling at high speed or low speed.

Next, the suppliable current prediction unit 24 determines whether or not the engine 61 is idling based on the acquired rotation speed n (S13) of the engine 61 (S23). Is set (F = 1) or not (S47). If the flag F is not set, the engine control unit 60 is instructed to increase the rotational speed n of the engine 61 by a predetermined rotational speed (S49), then the flag F is set (S51), and time measurement is started (S21). It is determined whether or not the measurement of the predetermined time T2 from () has ended (S27).
If the flag F is set (S47), the suppliable current prediction unit 24 determines whether or not the time measurement for the predetermined time T2 from the time measurement start (S21) has ended (S27).

  The supplyable current prediction unit 24 determines whether or not the flag F is set if the engine 61 is not idling (S23) (S25). If the flag F is not set, the time measurement starts (S21). It is determined whether or not the measurement of the predetermined time T2 from the end has been completed (S27). If the flag F is set, the engine controller 60 is instructed to restore the engine speed n of the engine 61 that has been increased by a predetermined engine speed (S53), and then the flag F is reset (S55). It is determined whether or not the time measurement for a predetermined time T2 from the time measurement start (S21) has ended (S27).

The supplyable current prediction unit 24 determines whether or not the engine 61 is idling (S23) if the time measurement for the predetermined time T2 from the start of the time measurement (S21) has not ended (S27).
The power supply control ECU 20 resets the time measurement (S29) when the time measurement for the predetermined time T2 is completed in the suppliable current prediction unit 24 (S27), and then the electric load 41 disconnected in the switching unit 25 is obtained. , 42... Are connected and restored (load control) (S31).

Next, the power supply control ECU 20 determines whether or not the suppliable current prediction unit 24 sets the flag F (S33). If the flag F is set, the power supply control ECU 20 sends the predetermined number of rotations to the engine control unit 60. An instruction is given to restore the engine speed n of the engine 61 that has been raised (S35). Next, after resetting the flag F (S37), the voltage value Vb and the current value Ib of the battery 10 are sampled (S5).
If the flag F is not set (S33), the supplyable current prediction unit 24 samples the voltage value Vb and current value Ib of the battery 10 as it is (S5).

It is a block diagram which shows schematic structure of embodiment of the supplyable current prediction apparatus and power supply control apparatus which concern on this invention. It is a circuit diagram which shows the outline | summary connection example of a battery, an alternator, and an electrical load. It is a flowchart which shows the process sequence of the supplyable current prediction apparatus and power supply control apparatus which concern on this invention. It is a flowchart which shows the process sequence of the supplyable current prediction apparatus and power supply control apparatus which concern on this invention. It is a characteristic view which shows the voltage-current characteristic of a battery. It is a characteristic view which shows each voltage-current characteristic of a battery, an alternator, and an electric load. It is a characteristic view which shows each example of the maximum output current value (a) of an alternator, and an external load characteristic (b).

Explanation of symbols

10 battery 20 power control ECU
DESCRIPTION OF SYMBOLS 21 Voltage detection part 22 Current detection part 23 Voltage current characteristic calculation part 24 Supplyable current prediction part 25 Switching part 41 Air conditioner / heater (electric load)
42 Headlight (electric load)
43 Fog lamp (electric load)
44 Defogah (electric load)
50 Alternator (on-vehicle generator, AC generator)
51 Temperature Detector 60 Engine Control Unit 61 Engine 62 Revolution Detector

Claims (5)

Means for sampling a voltage value and a current value of a battery for a vehicle to which a plurality of electric loads are connected; and means for calculating a voltage-current characteristic of the battery based on the voltage value and the current value sampled by the means. , A supplyable current prediction device for predicting a supplyable current value that can be supplied through the battery based on the voltage-current characteristic calculated by the means,
A rotational speed detector for detecting the rotational speed of the engine, a temperature detector for detecting the temperature of the in-vehicle generator linked to the engine, and the maximum output current value of the in-vehicle generator according to the rotational speed and temperature are stored. A reference table, means for obtaining a maximum output current value by referring to the reference table based on the number of revolutions detected by the revolution number detector and the temperature detected by the temperature detector; A suppliable current prediction apparatus comprising: a predicting unit that predicts a suppliable current value based on the acquired maximum output current value and the voltage-current characteristic.   The prediction means is a current when the voltage value of the battery is the lower limit voltage value based on the lower limit voltage value of the battery determined based on the voltage value required by the electric load and the voltage-current characteristic. The supplyable current prediction apparatus according to claim 1, wherein a supplyable current value is predicted by calculating a value and adding the calculated current value and the maximum output current value. In a power supply control device that controls electric power supplied to a plurality of electric loads through a vehicle battery,
The suppliable current predicting device according to claim 1, means for determining whether or not the suppliable current value predicted by the suppliable current predicting device is smaller than a predetermined current value, and the means is small A power supply control device comprising: a stop / restriction unit that selectively stops or restricts the supply of power to the electric load for a predetermined time when it is determined.   A means for comparing the rotation speed detected by the rotation speed detector for detecting the rotation speed of the engine with a predetermined rotation speed is further provided, and the stop / limit means applies the electric load to the electric load according to the comparison result of the means. 4. The power supply control device according to claim 3, wherein the power supply control device is configured to selectively stop or limit the supply of electric power.   When the stop / limit means selectively stops or restricts the supply of electric power to the electric load, the engine is idled based on the rotation speed detected by the rotation speed detector that detects the rotation speed of the engine. The power supply according to claim 3 or 4, further comprising: means for determining whether or not the engine is idling; and means for increasing the engine speed by a predetermined amount when it is determined that the means is idling. Control device.

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