JP2007168638A - Load drive control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a power supply control to the other load to ensure power supply to an important load at the voltage drop of a battery. <P>SOLUTION: The load drive control device removes an important load related to traveling and safety, and has large power consumption. The load drive control device is equipped with a battery voltage detection means for measuring an output voltage of a battery mounted in a vehicle, a power supply control means for determining the ratio between a connection time of a load to the battery and a shut-off time according to the battery output voltage detected by the battery voltage detection means, and a load control means for connecting or shutting-off the load with or from the battery. The load control means is equipped with a pulse control means which classifies the load into a plurality of groups and sets them by making the cycle different for each group to be classified according to the cycle of the connection and shut-off with the battery, and determines timing for connecting or shutting off each load with or from the battery from the ratio between the connection time and the shut-off time determined by the power supply control means and the cycle set by the load control means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle load drive control device, and in particular, distributes power supplied from a battery according to a load.

In recent years, drive members mounted on automobiles tend to be electric, and the burden on the battery tends to increase. For example, in an automobile steering section, an electric steering device called electric power steering (EPS) is used instead of hydraulic power steering. Further, assist functions such as an electric brake and a collision accident prevention system including a so-called “pre-crash system” also increase an electric load. Furthermore, in addition to the EPS, the electric brake, and the collision accident prevention system, some important loads including an airbag system require a large amount of electric power instantaneously.
However, since there is a limit to the power supply amount of the battery that can be mounted on the vehicle, the power supply to the load is insufficient at the momentary peak power consumption, and the comfort of the vehicle is impaired.

For example, in Japanese Patent Application Laid-Open No. 2004-142661 (reference document 1), priority is given to electric loads, and power supply is reduced or cut off for loads with low priority. Power supply is secured.
However, even if the power supply is reduced according to the priority, the timing for reducing or shutting off the power supply to each load is not considered, so if the timing of power supply to multiple loads overlaps Voltage fluctuation increases. In addition, since the load target is not limited, there is a case where power supply is reduced or cut off even for a load with low power consumption, which is not very effective in reducing power supply.

JP 2004-142661 A

  The present invention has been made in view of the above problems. When the battery voltage drops, the power supply is controlled to such an extent that comfort can be maintained for loads other than the important load, and the power for driving the important load is controlled. It is an issue to be able to ensure.

In order to solve the above-mentioned problems, the present invention is a drive control device for a load that consumes a large amount of power while removing an important load related to running and safety,
Battery voltage detection means for measuring the output voltage of the battery mounted on the vehicle;
Power supply control means for determining a ratio between a connection time and a cut-off time of the load according to a battery output voltage detected by the battery voltage detection means,
Load control means for connecting or disconnecting the load and the battery based on a command of the supply control means;
The load control means classifies the load into a plurality of groups according to the cycle of connection and disconnection with the battery and sets the cycle different for each group classified,
Pulse control for determining the timing of connecting or disconnecting each load to the battery from the ratio between the connection time and the disconnection time of the load determined by the power supply control means and the period set by the load control means There is provided a vehicle load drive control device characterized by comprising means.

As described above, in the present invention, safety is ensured by first removing the important load related to running and safety from the load to be controlled for power supply. In addition, because it targets loads with high power consumption among loads other than critical loads, the effect of temporary interruption of power supply can be increased, and power to critical loads can be reduced even when the battery output voltage decreases. Can be secured.
Furthermore, the loads to be controlled are divided into groups according to the cycle of power supply and cut-off, and this cycle is set so that the time during which the power supply is cut off does not impair comfort, and the cycle of power supply of each group Therefore, the timing of power supply is shifted and voltage fluctuations can be suppressed.
In particular, in the present invention, as described above, both the connection / disconnection cycle with the battery set for each group and the ratio of connection / disconnection with the battery according to the output voltage of the battery are taken into account. Since pulse control is performed, voltage fluctuations can be suppressed without impairing comfort due to power supply control.

The load that is driven and controlled and that consumes a large amount of power is a load that includes a defogger, an air conditioner, and a heater and that can temporarily cut off power supply.
The air conditioner, heater, etc. are not directly related to the running system or safety system, but are intended to make the comfort in the passenger compartment comfortable. There is no problem with blocking. Moreover, since these devices consume a large amount of power, the effect of power supply control is great, and accordingly, the power supplied to the traveling system and safety loads can be efficiently secured.

In addition, since each group includes a plurality of loads, it is preferable that a time difference is provided in connection / cutoff timing for each load in each group by the load control means.
With the above configuration, since the timings of connection / cutoff of the plurality of electric loads included in each group to the battery do not overlap, a large fluctuation in the output voltage of the battery can be prevented.

As described above, in the present invention, safety is ensured by removing an important load related to traveling and safety from a load to be controlled for power supply. In addition, because it targets loads with high power consumption among loads other than critical loads, the effect of temporary interruption of power supply can be increased, and power to critical loads can be reduced even when the battery output voltage decreases. Can be secured.
Furthermore, the loads to be controlled are divided into groups according to the cycle of power supply and cut-off, and this cycle is set so that the time during which the power supply is cut off does not impair comfort, and the cycle of power supply of each group Therefore, the timing of power supply is shifted and voltage fluctuations can be suppressed.
In particular, in the present invention, as described above, both the connection / disconnection cycle with the battery set for each group and the ratio of connection / disconnection with the battery according to the output voltage of the battery are taken into account. Since pulse control is performed, voltage fluctuations can be suppressed without impairing comfort due to power supply control.
Furthermore, since the configuration is such that the connection / cutoff timings of the plurality of loads to / from the battery are not overlapped as much as possible, battery voltage fluctuations can be prevented.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a configuration of a load drive control device 10 of the present invention. In FIG. 1, the load drive control device 10 has a configuration in which one is connected to the battery 1 and the other is connected to the ECUs 2a to 2c. The battery 1 is directly connected to the ECUs 2d and 2e.

The ECUs 2a to 2c are loads excluding important loads related to running and safety. For example, air conditioning load such as air conditioner and electric heater, warm air load such as defogger and seat heater, auxiliary lighting load such as room lamp and fog lamp, headlight lighting load, accessory load, etc. Yes, it is a load that can temporarily cut off power supply. When the voltage drop of the battery 1 is large, the battery power supply system 10 restricts the power supply to these load ECUs 2a to 2c in order to secure the necessary power amount for the important load.
The ECUs 2d and 2e are important loads such as EPS, electric brakes, collision accident prevention systems, and airbag systems. These important loads are directly connected to the battery 1 because the power supply is not limited to ensure safety.

  The power supply is limited by pulse control that periodically connects or disconnects the ECUs 2 a to 2 c to the battery 1. There is a limit to the setting of the pulse control cycle (pulse cycle) for connecting / disconnecting the battery 1 depending on each load. For example, when performing pulse control on the light, the pulse cycle is such that the light is not turned on or off by humans. Otherwise comfort is lost. Loads with similar pulse periods are treated as one group. In FIG. 1, ECUs 2a1-2a3 are groups of loads with similar pulse periods, and ECUs 2b1-2b3 are groups of different pulse periods.

The load drive control device 10 includes a voltage sensor 21, a power supply control unit 22, and a load control unit 23. The load control unit 23 includes a switch command unit 31 and a latch relay 32.
The voltage sensor 21 constitutes battery voltage detection means for measuring the output voltage of the battery 1, and inputs the voltage value measured by the voltage sensor 21 to the power supply control means 22.
Based on the voltage value input from the voltage sensor 21, the power supply control unit 22 outputs to the load control unit 23 the ratio of the connection / cutoff time of the ECU to the battery 1 in order to limit the power supply to the ECUs 2 a to 2 c.
The load control means 23 is connected to each group of loads, and includes a switch command means 31 and a latch relay 32.
The switch command means 31a to 31c receive a command of the ratio of connection / cutoff time of the ECUs 2a to 2c to the battery 1 from the power supply control means 22, and determine the connection / cutoff timing of the ECUs 2a to 2c.
The latch relays 32a to 32c are connected between the battery 1 and the ECUs 2a to 2c for each of the ECUs 2a to 2c, receive signals from the switch command units 31a to 31c, and connect or disconnect the ECUs 2a to 2c to the battery 1.

FIG. 2 is an explanatory diagram of power pulse control. The power supply can be limited by setting the pulse period to Δt and alternately providing the connection time a and the cutoff time b to the battery 1 of the ECUs 2a to 2c. Here, assuming that the duty cycle d, which is the ratio between a and b, is defined as the following equation (1), assuming that the pulse period Δt = a + b, the power supply amount at the duty cycle d is d times that when pulse control is not performed. It becomes. By determining the duty ratio d, the amount of power supplied to the ECUs 2a to 2c can be determined.
d = a / Δt = a / (a + b) (1)

  FIG. 3 shows an example of how to determine the duty ratio d. The power supply control means 22 determines the value of the duty ratio d according to the output voltage value of the battery 1 measured by the voltage sensor 21. When the important load is not activated and the output voltage of the battery 1 does not drop, it is not necessary to limit the power supply to the load. Therefore, the duty ratio d is 1, and the power supply is not limited and is always power. Is supplied. When the threshold value 1 is set and the output voltage of the battery 1 is lower than the threshold value 1, the duty ratio d is set to 0.75, for example, so that the power supply amount is three-fourths that of the constant power supply. Similarly, threshold values 2 and 3 are set, and the duty ratio d is also changed by a decrease in the output voltage of the battery 1.

  When returning from the state where the power supply is limited to, for example, when shifting from the section A to the section B in FIG. 3, the values of the output voltage of the battery 1 are the same in both the sections A and B, but the duty ratio d From 0.25 to 0. That is, the duty ratio d is set to a value that is less likely to be supplied with voltage in the section B when power supply is restored. By setting the duty ratio d lower at the time of return than when the power supply is restricted, the power supply to the load is increased at the time of power supply return and the output voltage of the battery 1 is prevented from lowering.

  Although the duty ratio d is determined by the power supply control means 22 using the value of the output voltage of the battery 1, the output voltage value may show an abnormal value due to an instantaneous load fluctuation or noise. When such a voltage value is used, a value different from the duty ratio d that should be originally set is set, and the power supply to the ECUs 2a to 2c increases too much, and the output voltage of the battery 1 is further reduced, or the power supply is more than necessary. This will cause a loss of comfort. For this reason, it is preferable to calculate the average value of the output voltage value per specified time and use it to determine the duty ratio d.

FIG. 4 is an explanatory diagram of the timing of voltage supply. The ECUs 2a1 to 2a3, the ECUs 2b1 to 2b3, and the ECUs 2c1 to 2c3 form groups a, b, and c for each pulse period. The pulse period of the group a is Δta, the pulse period of the group b is Δtb, and the pulse period of the group c. Is Δtc. In each group, each ECU is connected to the battery 1 for the time t shown in the following expression (2) from the start of the period of each pulse cycle, and the other time is disconnected from the battery 1. Since the pulse period is different for each group, the connection time to the battery 1 is also different for each group. FIG. 4 is a timing chart of power supply when the duty ratio d is 0.5. Since the ECUs 2d and 2e are important loads, electric power is always supplied and power supply is not limited.
Thus, by limiting the power supply to the loads other than the important load by pulse control, sufficient power can be supplied to the important load, and the voltage drop of the battery 1 can be prevented.
t = d × Δtp (p is the type of load group) (2)

FIG. 5 is an explanatory diagram when a time difference is given to the connection / cutoff timing of each ECU in one group, and the duty ratio d is 0.5. A plurality of ECUs, which are loads, are connected to one group, and a time difference is given to the connection / cutoff timing of each ECU.
The connection time von to the battery 1 per pulse period Δtp for each ECU is as shown in Expression (3), and the cutoff time Voff from the battery 1 is as shown in Expression (4).
When there are n loads in the load group, equation (5)
As shown in FIG. 4, a time difference u corresponding to n−1 equal parts of the pulse period Δtp is provided.
von = a / (a + b) × Δtp (3)
voff = Δtp−von = b / (a + b) × Δtp (4)
u = Δtp / (n−1) (5)

By using the above equation (5), it is easy to program the timing of connection of loads, and even when considering an actual microcomputer, the on / off timings of the loads are unlikely to overlap. Further, the time difference u can be set to n−1 equal parts of the cutoff time Voff as shown in the equation (6).
u = voff / (n−1) = b / ((n−1) (a + b)) × Δtp (6)

When the loads of the ECUs 2a1 to 2a3 exist in the group a, the connection / cutoff timing of each load is as follows.
ECU2a1 connection: t, t + Δta, t + 2Δta, ...
Blocking: t + von, t + von + Δta, t + von + 2Δta, ...
ECU2a2 connection: t + u, t + Δta + u, t + 2Δta + u, ...
Blocking: t + von + u, t + von + Δta + u, t + von + 2Δta + u, ...
ECU2a3 connection: t + 2u, t + Δta + 2u, t + 2Δta + 2u, ...
Blocking: t + von + 2u, t + von + Δta + 2u, t + von + 2Δta + 2u, ...
If there are n loads,
Connection: t + (n−1) u, t + Δta + (n−1) u, t + 2Δta + (n−1) u,.
Blocking: t + von + (n−1) u, t + von + Δta + (n−1) u, t + von + 2Δta + (n−1) u,.
In this way, when there are a plurality of ECUs in the group, if there is a time difference between the connection and disconnection timings of the ECUs, the ECUs in the group will not be connected to or disconnected from the battery 1 at the same time. Is unlikely to occur.

FIG. 6 shows a pulse control flowchart.
In step S1, it is determined whether the ignition key is on or off. If the ignition key is on, the process proceeds to step S2. When the ignition key is off, the state of the ignition key is detected again.
In step S <b> 2, the output voltage of the battery 1 is measured by the voltage sensor 21.
In step S <b> 3, the power supply control unit 22 determines the duty ratio d from the output voltage of the battery 1 and transmits d to the load control unit 23.
In step S4, the switch command means 31 in the load control means 23 determines the connection / cutoff timing of the ECU from the battery 1 from the number of ECUs in the group and the duty ratio d.
In step S5, the latch relay 32 connects and disconnects the ECU 1 from the battery 1 at the timing determined in S4. After that, the process returns to S1, and if the ignition key is on, the operation from S2 is repeated.

  As described above, by using the load drive control device 10 of the present invention, the loads to be controlled are grouped according to the cycle of power supply and shutoff, and the time for shutting off the power supply in this cycle impairs comfort. Since the power supply period of each group is varied, the power supply time is shifted, and voltage fluctuations can be suppressed.

It is a block diagram which shows the structure of a load drive control apparatus. It is explanatory drawing of pulse control. It is explanatory drawing of how to determine the duty ratio d. It is explanatory drawing of the timing of connection and interruption | blocking to the battery of ECU. It is explanatory drawing of the timing of connection and interruption | blocking of ECU when several ECU is connected to a group. It is a flowchart of pulse control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Load drive control apparatus 21 Voltage sensor 22 Power supply control means 23 Load control means 31 Switch command means 32 Latch relay

Claims (3)

A drive control device for loads that consumes a large amount of power while removing important loads related to driving and safety,
Battery voltage detection means for measuring the output voltage of the battery mounted on the vehicle;
Power supply control means for determining a ratio between a connection time and a cut-off time of the load according to a battery output voltage detected by the battery voltage detection means,
Load control means for connecting or disconnecting the load and the battery based on a command of the supply control means;
The load control means classifies the load into a plurality of groups according to the cycle of connection and disconnection with the battery and sets the cycle different for each group classified,
Pulse control for determining the timing of connecting or disconnecting each load to the battery from the ratio between the connection time and the disconnection time of the load determined by the power supply control means and the period set by the load control means A vehicle load drive control device comprising: means.   2. The vehicle load drive control device according to claim 1, wherein the drive-controlled load with high power consumption is a load that includes a defogger, an air conditioner, and a heater and that can temporarily interrupt power supply.   3. The vehicle load drive control device according to claim 1, wherein each group includes a plurality of loads, and the load control unit sets a time difference in connection / cutoff timing for each load in each group.

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