JPH11178228A - Power supply unit for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit for electric vehicle having little power supply loss and can improve reliability in charging a main battery for an electric vehicle through a commercial power source more sharply than a conventional type. SOLUTION: A low-voltage output part 42, which is capable of feeding power supply voltage to a battery controller 3, is newly formed at a DC power source 4 for conducting feeding to a main battery 1 from a commercial power source. A the time of charging the main battery 1, the low-voltage output party 42 applies power supply voltage to the battery controller 3 with priority given over applying power supply voltage to the battery controller 3 from an auxiliary battery 2. It is thus possible to prevent the auxiliary battery 2 from being exhausted, and the operation of battery controller 3 from becoming more unstable than it, even at long charging, such as uniform charging of the main battery 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply for an electric vehicle.

[0002]

2. Description of the Related Art In an electric vehicle, there is known a two-battery type power supply configuration in which a low-voltage auxiliary battery for driving a control device and on-vehicle auxiliary equipment is provided in addition to a high-voltage main battery for supplying power to a traveling motor. ing. The main battery is charged by a vehicle-mounted engine or a commercial power supply, but a hybrid electric vehicle using a vehicle-mounted engine is also charged by a commercial power supply in some cases.

A charging method using a commercial power supply in an electric vehicle having a two-battery power supply configuration will be described with reference to FIG.
1 is a high voltage (288) power supply to a traveling motor (not shown).
V) main battery 2, and a low voltage (12) for supplying power to an on-vehicle auxiliary device such as a fan motor M for driving a battery cooling fan.
V) Auxiliary battery 3, a battery ECU (battery controller) that is supplied with a power supply voltage by the auxiliary battery 2 and controls charging and discharging of the main battery 1 while monitoring the main battery 1, and 4 converts commercial power to high-voltage DC power A DC power supply device 5 having a high-voltage output unit 41 for converting and supplying power to the main battery 1 is a DC-DC power supply device 5 for supplying power from the main battery 1 and charging the auxiliary battery 2.
A converter 6 is a relay for opening and closing power supply from the auxiliary battery 2 to the fan motor M, and a relay 7 is for opening and closing power supply from the high voltage output unit 11 to the main battery 1.

A high-voltage output section 41 of a DC power supply 4 usually provided outside the vehicle supplies power to the main battery 1 through a relay 7, and the main battery 1 supplies power to an auxiliary battery 2 through a DC-DC converter 5. The auxiliary battery 2 supplies power to the fan motor M through the relay 6 and the ignition switch I
A power supply voltage is applied to the battery ECU 3 through G.

[0005]

However, in the above-described electric vehicle having the conventional two-battery power supply configuration, when the main battery 1 is equally charged by the DC power supply 4, the auxiliary battery 2 is used for a long time. Battery E
Since the power supply must be supplied to the CU 3, there is a possibility that the power supply voltage of the battery ECU 3 decreases due to the consumption of the auxiliary battery 2 and the operation thereof becomes unstable. In addition, there is a possibility that the battery ECU 3 may be dropped by accidentally dropping a switch means such as an ignition switch for opening and closing the power supply from the auxiliary battery 2 to the battery ECU 3. In the charging operation of the main battery 1 described above, the charging current may be controlled with reference to the past charging history. There is a possibility that the battery 1 may be overcharged.

Of course, the consumption of the auxiliary battery 2 is
The auxiliary battery 2 can be charged by detecting the CU 3 and driving the DC-DC converter 5. However, in this case, the power supply voltage of the battery ECU 3 changes suddenly, Since the charging current changes suddenly, the control becomes complicated, and the power supply from the DC-DC converter converts the commercial power to high-voltage DC power, and further converts this high-voltage DC power to low-voltage DC power. The DC power supply 4 is installed in a service center, for example, where the auxiliary battery 2 and the main battery 1 are installed.
In both cases, consider the case where a worn-out electric vehicle is brought in. In charging the main battery 1 in this case, the DC power supply 4 itself must independently control the charging of the main battery 1 because the battery ECU 3 does not start up because the auxiliary battery 2 has been exhausted conventionally. . However, during the charging operation of the main battery 1, the battery ECU
Although it is preferable to refer to the charging / discharging history and the specific information of the main battery 1 stored in the main battery 1 up to this point, when the DC power supply 4 itself performs the operation, There is a problem that detailed charging control cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the reliability of the charging operation of the main battery of an electric vehicle using a commercial power source can be significantly improved by a simple configuration with a small power loss. It is an object of the present invention to provide a power supply device for an electric vehicle.

[0008]

According to the first aspect of the present invention, a low-voltage output unit capable of supplying a power supply voltage to a battery controller is newly provided in a DC power supply for supplying power to a main battery from a commercial power supply. . Further, the low-voltage output unit applies the power supply voltage to the battery controller prior to the application of the power supply voltage from the auxiliary battery to the battery controller when charging the main battery.

In this way, even during long-time charging such as equal charging of the main battery, the auxiliary battery is not consumed and the operation of the battery controller does not become unstable. Further, even when the power supply from the auxiliary battery to the battery controller is interrupted for some reason, or when the power supply from the DC power supply to the battery controller is interrupted for some reason, the battery controller can be operated without any trouble. .

Further, even when the auxiliary battery is severely consumed, the charging of the main battery can be controlled by the battery controller without any problem. Further, since it is not necessary to perform two-stage power conversion for charging the auxiliary battery, it is also possible to improve the power usage efficiency when charging the main battery. In the automotive power supply, the auxiliary battery and the low-voltage output section of the DC power supply supply power to the power supply terminal of the battery controller through different diodes, respectively, and further set the output voltage of the low-voltage output section higher than that of the auxiliary battery. With this configuration, the priority power supply of the low-voltage output unit described in claim 1 can be realized only by adding a simple configuration of adding a pair of diodes, and furthermore, the power supply voltage from one of them is suddenly cut off,
According to the third aspect of the present invention, in the power supply device for an electric vehicle according to the second aspect, the main battery may further include: At least when the battery temperature at the time of charging is equal to or higher than a predetermined value, air is cooled by the cooling fan.

In this configuration, in particular, the fan motor is supplied with power from the low-voltage output unit when the main battery is charged by the high-voltage output unit of the DC power supply, and when the power supply from the low-voltage output unit to the fan motor is started, the fan motor is supplied from the auxiliary motor. Power is supplied to With this configuration, even when the output impedance of the low-voltage output unit is high, the output voltage of the low-voltage output unit is greatly reduced due to the large startup current at the time of large startup of the fan motor, and the voltage applied to the battery controller is reduced. Can be eliminated.

According to a fourth aspect of the present invention, in the power supply device for an electric vehicle according to the second aspect, the main battery is air-cooled by a cooling fan when at least a battery temperature at the time of charging is higher than a predetermined value. Is driven by the low-voltage output unit during charging by the high-voltage output unit, and is driven by the auxiliary battery during vehicle running.

In this configuration, particularly when the voltage of the auxiliary battery is low when charging the main battery in the high voltage output section,
The switch means on the path for supplying power from the auxiliary battery to the fan motor is turned on. With this configuration, the auxiliary battery can be charged by the low-voltage output section by flowing backward in the above-described path, and simplification of wiring can be realized. This auxiliary equipment charging is performed completely separately from the main battery charging by the high-voltage output unit, so that it does not have a potential effect on the main battery charging, and is further performed by one-step power conversion from the commercial power supply by the low-voltage output unit. Since it can supply power to the auxiliary battery,
Low power loss.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples. The electric vehicle of the present invention may be a pure electric vehicle having no engine or a hybrid vehicle using an engine.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the power supply device for an electric vehicle according to the present invention will be described with reference to the drawings. (Circuit Description) The circuit configuration of this electric vehicle power supply device will be described with reference to FIG. 1 is a high-voltage (288 V) main battery that supplies power to a traveling motor (not shown), 2 is a low-voltage (12 V) auxiliary battery that supplies power to vehicle-mounted auxiliary equipment such as a fan motor M for driving a battery cooling fan, and 3. Is a battery ECU (battery controller) that is supplied with a power supply voltage from the auxiliary battery 2 and controls charging and discharging of the main battery 1 while monitoring the main battery 1, 4 is a DC power supply device, and 6 is a power supply from the auxiliary battery 2 to the fan motor M A relay 7 for opening and closing power supply is a relay for opening and closing power supply from the high voltage output unit 11 to the main battery 1.

The DC power supply unit 4 converts a commercial power supply into a high-voltage (about 290 V) DC power and feeds it to the main battery 1.
V) and a low-voltage output section 42 for converting the DC power into power and supplying power to the auxiliary battery 2. Since the high-voltage output unit 41 and the low-voltage output unit 42 are known as DC-DC converters, detailed description thereof will be omitted.

The battery ECU 3 includes a microcomputer device 31, a power supply circuit 32 for applying a power supply voltage to the microcomputer device 31, and a high power supply terminal 3 reaching the power supply circuit 32 from the low voltage output section 42.
A power supply path to the power supply circuit 20; and a diode 34 provided in a power supply path from the auxiliary battery 2 to the high-level power supply terminal 320 of the power supply circuit 32 through the ignition switch IG. Microcomputer device 31
Monitors the voltage of the main battery 1 and the auxiliary battery 2 and controls the opening and closing of the relays 6 and 7 based on the monitoring. In this embodiment, in order to reduce the cost and the weight of the vehicle, only the DC power supply device 4 serving as the DC power supply according to the present invention is fixed to the ground (service station) side.
Other circuits and devices are mounted on the electric vehicle. Of course, it goes without saying that the DC power supply 4 may be always mounted on the electric vehicle.

(Explanation of Charging Operation) The charging operation of the main battery 1 by the DC power supply device 4, which is a characteristic operation of this device, will be described below. First, the high voltage output unit 41
Are connected to both ends of the main battery 1 through the relay 7, and both ends of the low voltage output section 42 are connected to the ground line of the battery ECU 3 and the anode of the diode 33. Further, the high output line of the low voltage output section 42 is connected to the high power input terminal of the fan motor M which is a DC motor. Further, the ignition switch IG is turned on, and the battery ECU 3 is started.

Next, when the connector of the DC power supply 4 is connected to the commercial power supply, a power reception completion signal is sent to the battery ECU 3, which turns on the relay 6 and outputs a high voltage output 41 to the DC power supply 4. The high-voltage output and the low-voltage output from the low-voltage output unit 42 are commanded. Thereby, the main battery 1 is charged by the high-voltage output unit 41,
The fan motor M is started, and the battery ECU 3 is supplied with the power supply voltage from the low voltage output unit 42. It should be noted that the low pressure output section 42
Is about 14 V, which is set slightly higher than the full charge voltage of the auxiliary battery 2.

A large starting current flows through the fan motor M, and the voltage at the high power input terminal of the fan motor M decreases. However, when the voltage at the high power input terminal of the fan motor M decreases, the auxiliary battery Since the power is supplied from the power supply 2 to the fan motor M, a decrease in the output voltage of the low-voltage output unit 42 is suppressed. Further, in this embodiment, the battery EC
Since U3 is supplied with power from both the auxiliary battery 2 and the low-voltage output unit 42, it is possible to properly prevent the power supply voltage of the microcomputer device 31 from being lowered due to the voltage drop of the low-voltage output unit 42.

The battery ECU 3 is shut off after the start of the fan motor M, but the battery ECU 3 monitors the capacity of the auxiliary battery 2 and, when the capacity drops below a predetermined value, turns on the relay 6 to turn on the low voltage output section. When the capacity of the auxiliary battery 2 recovers to a predetermined value or more, the relay 6 is turned off and the charging of the auxiliary battery 2 by the low voltage output unit 42 is stopped.

Thereafter, when the terminal voltage of the main battery 1 reaches a certain voltage, the relay 7 is cut off to terminate the charging operation. (Modification 1) In the above-described embodiment, the relay 6 is turned on only when the fan motor M is started and when the voltage of the auxiliary battery 2 drops, but is always turned on during the charging period of the main battery 1 by the high voltage output unit 41. You may. By doing so, the auxiliary battery 2 can also be charged. However, in this case, the output voltage of the low-voltage output unit 42 is almost equal to the voltage of the high-order power supply input terminal when the fan battery M is operating, so that the auxiliary battery 2 is not overcharged. The level must be equal to the charging voltage. (Modification 2) In the above embodiment, the relay 6 is turned on only when the fan motor M is started and when the voltage of the auxiliary battery 2 drops,
In the above modification, the relay 6 is always turned on during the charging period of the main battery 1 by the high voltage output unit 41. In this embodiment, the relay 6 is turned on when the fan motor M is started, and thereafter, the charging of the auxiliary battery 2 is performed. Turns off when the state reaches a predetermined level. By doing so, the output voltage of the low-voltage output unit 42 can be set higher than in the case of the first modification, and the auxiliary battery 2 can be charged, which is simple.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a power supply device for an electric vehicle according to the present invention.

FIG. 2 is a block circuit diagram showing a conventional electric vehicle power supply device.

[Explanation of symbols]

1 is a main battery, 2 is an auxiliary battery, 3 is a battery controller (battery ECU), 4 is a DC power supply (DC power supply),
6 is a relay (switching means).

Claims (4)

[Claims] 1. A high-voltage main battery for supplying power to a traveling motor, a low-voltage auxiliary battery for supplying power to an on-vehicle auxiliary device, and a power supply voltage supplied by the auxiliary battery to monitor and charge / discharge the main battery while monitoring the main battery. A battery controller for controlling, and a DC power supply having a high-voltage output unit for converting commercial power to high-voltage DC power and supplying power to the main battery. A low-voltage output unit that converts power supply power into low-voltage DC power and applies a power supply voltage to the battery controller in preference to a power supply voltage application from the auxiliary battery to the battery controller when the main battery is charged by the DC power supply. A power supply device for an electric vehicle, comprising: 2. The power supply device for an electric vehicle according to claim 1, wherein a diode interposed between the auxiliary battery and a power input terminal of the battery controller so as to apply the power supply voltage, and the DC power supply. A diode interposed between the low-voltage output unit and a power input terminal of the battery controller so as to be capable of applying the power supply voltage, wherein the low-voltage output unit of the DC power supply has an allowable range of the battery controller. And outputting a power supply voltage higher than the auxiliary battery to the battery controller. 3. The electric vehicle power supply device according to claim 2, further comprising a fan motor for driving a cooling fan for cooling the main battery by air, wherein the fan motor is provided by a high voltage output unit of the DC power supply. An electric vehicle power supply device, wherein power is supplied from the low-voltage output unit when the main battery is charged, and power is supplied from the auxiliary battery to the fan motor when the low-voltage output unit starts supplying power to the fan motor. . 4. The power supply device for an electric vehicle according to claim 2, further comprising a fan motor for driving a cooling fan for air-cooling said main battery, wherein said fan motor is provided by a high-voltage output unit of said DC power supply. When the main battery is charged, power is supplied from the low-voltage output unit. The auxiliary battery supplies power to the fan motor through the switching means. The battery controller monitors the auxiliary battery and reduces the voltage of the auxiliary battery. A power supply device for an electric vehicle, characterized in that control is performed to turn on the switch means and charge the auxiliary battery with the low-voltage output unit.