JP2004190626A - Power system controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an occupant of a vehicle from recognizing switch of two or more of secondary batteries having different characteristics when the secondary batteries are switched to be used. <P>SOLUTION: An idle stop control ECU 100 includes a circuit for switching so that the electric power is supplied to a starter 710 from a lithium ion battery 500 not from a lead-acid battery 400 by turning the electric current to a starter power supply switch relay 300 before stop of an engine 700 when an idle stop condition is established, a circuit for restarting the engine 700 by operating the starter 710 with the usage of the electric power supplied from the lithium ion battery 500 when an engine restart condition is established, and a circuit for switching so that the electric power is supplied to the starter 710 from the lead-acid battery 400 not from the lithium ion battery 500 by stopping supply of the electric current to the starter power supply switch relay 300 when a rotational frequency of the engine 700 is equal to or more than a predetermined rotational frequency. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control technology of a power supply for an automobile, and more particularly, to a switching control of two secondary batteries having different characteristics.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a 42V vehicle power supply system in which a 42V power supply is added to a conventional 14V power supply has been proposed in order to cope with the electrification and large capacity of onboard equipment such as an electric power steering and an electric air conditioner. Since the voltage of the 42V system power supply is three times that of the conventional 14V system, the current can be reduced to one third, and the loss can be reduced and the harness can be reduced in weight. In addition, it is easy to deal with a large capacity load. The capacity of the battery will be larger than before, and a nickel-metal hydride battery or a lithium-ion battery may be applied in the future in place of the current lead-acid battery.
[0003]
However, lamps and the like have disadvantages such as a shortened life when used at 42 V. Therefore, it is necessary to leave a conventional 14 V system as it is. Therefore, recently, a power supply system has been proposed which includes both a 42V-system main battery and a 14V-system sub-battery, and connects both of them with a DC / DC converter to control charging from the main battery to the sub-battery. Note that a 14V battery refers to a battery having a charging voltage of 14V and a discharging voltage of 12V. The 42V battery refers to a battery having a charging voltage of 42V and a discharging voltage of 36V.
[0004]
In addition, such a power supply system is applied to a vehicle having an idling stop function (a function for realizing good fuel economy by stopping an engine when the vehicle is temporarily stopped at a red light at an intersection or the like) to provide an idling stop function. During the operation, auxiliary equipment such as an air conditioner compressor, water pump, and power steering pump are operated by driving a motor generator with electric power supplied from a 42V main battery, and auxiliary equipment such as an electric air conditioner, a lamp, and an audio system. There is also a system in which power is reduced from a 42 V system main battery to 14 V by a DC / DC converter.
[0005]
When two power supplies having different characteristics are provided, a control device for controlling a 42V battery and a 14V battery is required. Japanese Patent Laying-Open No. 2001-239902 (Patent Document 1) discloses such a power supply control device. This control device operates a predetermined power load when the engine is stopped or the key switch is off when the remaining amount of the battery is measured, and operates the predetermined power load according to the priority of the power load. And a control unit configured to determine a plurality of thresholds of the remaining amount and to stop the operation in order from a power load having a lower priority as the remaining amount of the battery becomes smaller.
[0006]
According to this control device, the power load can be operated even when the engine is stopped or the key switch is turned off, and power is supplied only to a high-priority power load according to the remaining amount. A decrease in the amount can be prevented.
[0007]
[Patent Document 1]
JP 2001-239902 A
[Problems to be solved by the invention]
However, in the control device disclosed in Patent Literature 1, connection and disconnection between a power supply and a load are realized by a switch. If a switch is used to switch between a power supply and a load by using such a switch, or a switching relay is used to switch between two power supplies, the driver can hear a switching sound generated at the time of the switching. In particular, when an idling stop system is constructed using two power supplies having different characteristics and the two power supplies are switched and used by a relay, no engine sound or drive system vibration sound is generated at the time of idling stop, The switching sound is easily heard by the occupants of the vehicle.
[0009]
SUMMARY An advantage of some aspects of the invention is to provide a control device of a power supply system mounted on a vehicle, which is used by switching between power supplies having two or more different characteristics. An object of the present invention is to provide a control device of a power supply system that does not make a passenger of a vehicle aware of the switching when the vehicle is switched.
[0010]
[Means for Solving the Problems]
A control device according to a first aspect of the invention includes a plurality of secondary batteries having different characteristics and controls a power supply system used in a vehicle. The control device is configured to switch at a timing determined by the relay for switching the connection between the plurality of secondary batteries and the load mounted on the vehicle, a determination unit for determining the timing of switching the relay, and the timing determined by the determination unit. And control means for controlling the relay. The determining means includes a means for determining when the sound generated from the vehicle is loud as timing.
[0011]
According to the first invention, for example, in a power supply system composed of two batteries having different characteristics (42 V system and 14 V system, lithium ion battery, lead storage battery, etc.), the two or more batteries and vehicle auxiliary equipment The connection to the load is switched by a relay. The control means switches this relay at the timing determined by the determination means. The timing determined by the determination means is when the sound generated from the vehicle is loud. Therefore, when the control means switches the relay, the engine sound of the vehicle or the like is loud, and the switching noise of the relay is absorbed. As a result, it is possible to provide a power supply system control device that does not make the passenger of the vehicle aware of switching between two or more power supplies constituting the power supply system.
[0012]
In the control device according to the second invention, in addition to the configuration of the first invention, the determining means includes a means for determining when the engine of the vehicle is rotating as the timing.
[0013]
According to the second invention, when the engine of the vehicle is rotating and engine noise is generated, the connection between the two or more batteries and the load of the auxiliary equipment of the vehicle is switched by the relay. Therefore, the sound generated from the engine of the vehicle absorbs the sound of switching the relay.
[0014]
In the control device according to a third aspect of the present invention, in addition to the configuration of the first aspect, the determining means includes a means for determining before the automatic stop of the engine as the timing.
[0015]
According to the third invention, in a vehicle having an idle stop function for automatically stopping the engine when idling, before the engine of the vehicle is automatically stopped by the idle stop function, two or more batteries and loads of auxiliary equipment of the vehicle are reduced. Switch the connection with a relay. At this time, the relay is switched so that the engine is restarted by a specific battery. For this reason, a secondary battery suitable for restarting after the engine is automatically stopped can be used, and the sound generated from the engine of the vehicle absorbs the sound of switching the relay.
[0016]
In the control device according to a fourth aspect, in addition to the configuration of the third aspect, the relay includes a first battery used when starting the engine in conjunction with the ignition key, and the engine after being automatically stopped. And a relay for switching the connection between the second battery used when the engine is restarted and the engine starter. The judging means judges before the automatic stop of the engine as the timing for switching the connection destination of the starting device from the first battery to the second battery, and after restarting the engine, sets the connection destination of the starting device to the second battery. Means for determining the timing of switching from the battery to the first battery is included.
[0017]
According to the fourth invention, before the engine of the vehicle is automatically stopped by the idle stop function, the connection destination of the starter, which is the engine starter, is switched from the first battery (for example, a 12V lead storage battery) to the second battery. (For example, a 14 V lithium-ion battery), and after restarting the engine with the starter using the second battery, the connection destination of the starter is switched from the second battery to the first battery. For this reason, for the restart of the engine that is repeatedly executed after the engine is automatically stopped, a lithium ion battery suitable for such an application can be used, and a normal lead storage battery can be used for starting the engine by turning on the ignition. At the same time, the sound generated from the engine of the vehicle absorbs the sound of switching the switching relay between the starter, the first secondary battery, and the second secondary battery.
[0018]
In the control device according to the fifth invention, in addition to the configuration of the fourth invention, the relay connects the starting device to the first battery when the relay is not energized, and connects the starting device to the first battery when the relay is energized. A relay for switching to the second battery.
[0019]
According to the fifth aspect, after starting the engine by turning on the ignition, the relay is energized only during the idle stop period to connect the starter, which is the starting device, to the second secondary battery. In this way, the energization time can be shortened compared to a case where the relay is constantly energized and the starter as the starting device is connected to the second secondary battery after the ignition is turned on to start the engine, so that the energy efficiency is increased. The fuel efficiency of the vehicle is improved. Further, even when the relay is out of order, the vehicle can be operated normally as the starter is connected to the normal lead storage battery when power is not supplied.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed description thereof will not be repeated.
[0021]
Referring to FIG. 1, a control block diagram of a vehicle including an idling stop control ECU (Electronic Control Unit) which is a control device according to the present embodiment will be described. As shown in FIG. 1, the vehicle includes an idle stop control ECU 100 that realizes an idle stop function that automatically stops the engine when the vehicle stops at an intersection of a red light, an engine ECU 200 that controls the engine 700, A lead-acid battery 400 having a nominal voltage of 12 V, which is used during normal times, a lithium-ion battery 500 having a nominal voltage of 14.4 V, which is used only during the idle stop period, and a step-down converter for reducing power from the lithium-ion battery 500. A DC / DC converter 600 that supplies power to the lead-acid battery 400 and boosts the power from the lead-acid battery 400 to supply the lithium-ion battery 500, a starter 710 that is a starting device that cranks the engine 700, An alternator 720 for generating electric power by rotational force, The power supplied to starter 710 and a starter power supply changeover relay 300 to switch the power supply of the starter 710 to be supplied from one of the lead-acid battery 400 and the lithium ion battery 500.
[0022]
Further, the lead storage battery 400 includes a temperature sensor 410 for detecting the temperature of the lead storage battery 400 and a current sensor 420 for detecting the charge / discharge current of the lead storage battery 400. Lithium ion battery 500 includes a temperature sensor 510 for detecting the temperature of lithium ion battery 500, a current sensor 520 for detecting the charge / discharge current of the lithium ion battery, and a lithium ion battery relay 530. The idle stop control ECU 100 is connected to the engine ECU 200, and the engine ECU 200 implements a fuel cut for stopping the fuel supply to the engine 700 based on a signal received from the idle stop control ECU 100. The idle stop control ECU 100 switches the starter power supply switching relay 300 based on the satisfaction of the idle stop condition, the satisfaction of the engine restart condition, and the like, and supplies the power to the starter 710 from either the lead storage battery 400 or the lithium ion battery 500. Let it be supplied. Further, idle stop control ECU 100 receives the engine speed from engine ECU 200, and controls energization / de-energization of starter power supply switching relay 300 based on the engine speed.
[0023]
In this vehicle, when the driver turns the ignition key to the start position, electric power from the lead storage battery 400 is supplied to the starter 710 via the starter power supply switching relay 300, and the starter 710 starts the engine 700. During normal running, the generated power from alternator 720 is supplied to lead storage battery 400 and vehicle auxiliary equipment. When the SOC (State Of Charge) of lithium-ion battery 500 is low, lithium-ion battery 500 is charged via DC / DC converter 600. At the time of regenerative power generation, when engine ECU 200 detects that the vehicle is decelerating and other conditions are satisfied, fuel cut is performed, and regenerative power generation is performed by increasing the power generation voltage of alternator 710. The lithium-ion battery 500 is charged by the generated power.
[0024]
During idle stop, power is supplied from the lithium-ion battery 500 via the DC / DC converter 600 to the vehicle accessory and the electric oil pump of the automatic transmission. During the idle stop, the skid control computer keeps the hydraulic pressure of the wheel cylinders to prevent the vehicle from moving backward on an uphill road. When the engine is restarted, if the shift lever is in the D range, the engine 700 is restarted simultaneously with releasing the brake pedal. When the engine is restarted, the electric power of the lithium ion battery 500 is supplied to the starter 710, and the engine 700 is cranked by the starter 710.
[0025]
Thus, in this vehicle, when the engine is first started by the ignition key, power is supplied from the lead storage battery 400 to the starter 710, and when the engine is restarted after the idle stop, the starter 710 is connected to the lithium ion battery 500. The starter power supply switching relay 300 is controlled by the idle stop control ECU 100 so that power is supplied to the power supply.
[0026]
Referring to FIG. 2, a control structure of a program for executing a starter power supply switching process executed by idle stop control ECU 100 will be described.
[0027]
At step (hereinafter, step is abbreviated as S) 100, idle stop control ECU 100 determines whether or not an idle stop condition is satisfied. This determination is made based on the accelerator opening, the vehicle speed, the engine speed, the determination of the uphill road, the SOC of the lithium ion battery, and the like. If the idle stop condition is satisfied (YES in S100), the process proceeds to S200. If not (NO in S100), the process returns to S100 and waits until the idle stop condition is satisfied.
[0028]
In S200, idle stop control ECU 100 turns on the power supply to starter power supply switching relay 300. Starter power supply switching relay 300 is configured to supply electric power from lithium ion battery 500 to starter 700 in an energized state. At S300, idle stop control ECU 100 transmits a fuel cut execution request signal to the engine ECU. Thus, engine ECU 200 stops supplying fuel to engine 700, and engine 700 stops.
[0029]
In S400, idle stop control ECU 100 determines whether an engine restart condition has been satisfied. This condition is satisfied when the driver releases his / her foot from the brake pedal, performs a shift change, or when the SOC of the lithium-ion battery 500 has decreased. When the engine restart condition is satisfied (YES in S400), the process proceeds to S500. If not (NO in S400), the process returns to S400, and the idle stop is continued until the engine restart condition is satisfied.
[0030]
In S500, idle stop control ECU 100 uses starter 710 to restart engine 700 by starter 710. In S600, idle stop control ECU 100 determines whether or not the engine speed is 1000 rpm or more. If the engine speed is not less than 1000 rpm (YES in S600), the process proceeds to S700. If not (NO in S600), the process returns to S600, and waits until the engine speed becomes 1000 rpm or more.
[0031]
In S700, idle stop control ECU 100 turns off power supply to starter power supply switching relay 300.
[0032]
The operation of the vehicle including the idle stop control ECU 100 according to the present embodiment based on the above structure and flowchart will be described.
[0033]
When the vehicle stops at an intersection or the like at a red light and the brake pedal is depressed in the D range, an idle stop condition is satisfied (YES in S100). Electricity is supplied to starter power switching relay 300 by idle stop control ECU 100, and the relay is switched so that electric power from lithium ion battery 500 is supplied to starter 700 (S200). Fuel cut of engine 700 is performed by engine ECU 200, and engine 700 stops. That is, when the starter power switching relay 300 is switched, the engine 700 is rotating.
[0034]
As shown in FIG. 3, when the idle stop condition is satisfied and the fuel cut is started, the engine speed is rotating near the idle speed, and at that time, the power supply to the starter power supply switching relay 300 is started. , The relay switches. At this time, since the engine 700 is rotating, the sound generated from the engine 700 absorbs the switching sound of the starter power supply switching relay 300, and the occupant of the vehicle hardly hears the switching sound. Such a state continues during the idle stop period.
[0035]
When the starter power supply switching relay 300 is energized and the power from the lithium ion battery 500 is supplied to the starter 700 via the starter power supply switching relay 300, the driver restarts the engine by releasing the brake pedal or the like. When the start condition is satisfied (YES in S400), starter 710 starts engine 700 based on a control signal from idle stop control ECU 100. At this time, as shown in FIG. 3, since the engine restart condition is satisfied and the engine 700 is restarted, the engine 700 is cranked by the starter 710 and the engine 700 is started.
[0036]
When the engine speed becomes 1000 rpm or more (YES in S600), idle stop control ECU 100 switches the energized state of starter power supply switching relay 300 to the non-energized state (S700). That is, as shown in FIG. 3, when the engine speed becomes 1000 rpm or more, starter power supply switching relay 300 is switched from the energized state to the non-energized state. At this time, the rotation speed of the engine is sufficiently increased, and the sound generated by the engine absorbs the switching sound of the starter power supply switching relay 300.
[0037]
As described above, according to the idle stop control ECU according to the present embodiment, the starter power supply switching that switches between the lead storage battery used when the engine is started by the ignition key and the lithium ion battery used when the engine is restarted after the idle stop is performed. The switching of the relay is switched from the lead storage battery to the lithium ion battery before the idle stop condition is satisfied and the fuel cut is started, and when the engine speed becomes equal to or higher than the predetermined speed after the engine is restarted, the lithium ion battery is switched. To switch to lead-acid batteries. Therefore, when the starter power supply switching relay performs the switching operation, the engine is rotating, and the sound generated from the engine, the sound generated by the engine vibration or the vibration of the drive system to which the engine vibration propagated, etc. The switching sound of the starter power switching relay is absorbed. As a result, it is possible to prevent or (at least) suppress the occupant of the vehicle from recognizing that the power of the starter has been switched. In addition, it is conceivable that the starter power switching relay is always energized in order to set the starter power switching relay to the lithium ion battery side after the engine is started by the ignition key and until the ignition key is turned off. Then, the time for supplying power to the starter power supply switching relay becomes longer, which is not preferable in terms of energy efficiency. The idle stop control ECU according to the present embodiment minimizes the energization time to the starter power supply switching relay, so that energy efficiency can be increased and fuel efficiency of the vehicle can be improved.
[0038]
Note that the timing of switching the power supply of the starter may be a sound originating from a source other than the engine and a sound that stimulates the hearing of the occupant of the vehicle. For example, it may be a sound generated inside the vehicle by operating the air conditioner, or a sound generated from audio equipment.
[0039]
Further, at the timing of switching the power supply of the starter, the idle stop condition may be satisfied and the fuel cut may be performed at the same time.
[0040]
The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[Brief description of the drawings]
FIG. 1 is a control block diagram of a vehicle equipped with a control device according to the present embodiment.
FIG. 2 is a flowchart showing a control structure of a program executed by an idle stop control ECU shown in FIG.
FIG. 3 is a diagram showing a timing chart at the time of idling stop of the vehicle.
[Explanation of symbols]
100 Idle stop control ECU, 200 engine ECU, 300 starter power switching relay, 400 lead storage battery, 500 lithium ion battery, 600 DC / DC converter, 700 engine, 710 starter, 720 alternator.

Claims (5)

A control device for a power supply system including a plurality of secondary batteries having different characteristics and used for a vehicle,
A relay for switching a connection between the plurality of secondary batteries and a load mounted on the vehicle;
Determining means for determining the timing of switching the relay,
Control means for controlling the relay, so as to switch at the timing determined by the determination means,
The control device for a power supply system, wherein the determination unit includes a unit for determining when the sound generated from the vehicle is loud as the timing. The control device of the power supply system according to claim 1, wherein the determining unit includes a unit for determining when the engine of the vehicle is rotating as the timing. The vehicle has an idle stop function for automatically stopping the engine when idling,
The control device for a power supply system according to claim 1, wherein the determination unit includes a unit for determining before the automatic stop of the engine as the timing. The relay includes a first battery used when starting the engine in conjunction with an ignition key, a second battery used when restarting the engine after the automatic stop, and a starter for the engine. A relay for switching connections,
The determination means determines before the automatic stop of the engine as timing for switching the connection destination of the starting device from the first battery to the second battery, and determines after the restart of the engine the starting device. 4. The control device for a power supply system according to claim 3, further comprising: a unit configured to determine a connection destination of the first battery as the timing of switching from the second battery to the first battery. 5. The relay is a relay for switching the connection destination of the starting device to the first battery when the relay is de-energized, and the connection destination of the starting device to the second battery when energized. The control device of the power supply system according to the above.

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