JP3178139B2 - Control device for electric vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle equipped with a battery and its charging means, and more particularly to a control device for controlling charging of the battery.

[0002]

2. Description of the Related Art An electric vehicle is a vehicle driven by a motor. This motor is driven by electric power supplied from a vehicle-mounted battery. For example, when an AC motor is used as a motor, DC power output from a battery is converted into AC power by a circuit such as an inverter, and the motor is driven by the AC power. At this time, a desired output torque can be obtained from the motor by controlling the switching operation of each switching element constituting the inverter.

[0003] As an electric vehicle, a configuration in which a so-called engine-driven generator is further mounted is known. The engine-driven generator is a device that rotates the generator by the mechanical output of the engine and thereby obtains electric power. When an electric vehicle is configured as a so-called series hybrid vehicle, the power output of an engine-driven generator is supplied to the above-described traveling motor and battery. With such a device configuration,
Both the output of the engine-driven generator and the output of the battery can be used as the power for driving the motor, and the output of the engine-driven generator can be used for charging the battery.

[0004] As a device for controlling the charging of a battery by the output of an engine-driven generator, for example, Japanese Patent Laid-Open No. 55-1
There is an apparatus disclosed in Japanese Patent No. 57901. In this device, the state of charge (SOC) of the battery
) Is reduced, the engine-driven generator is started. When the engine-driven generator starts, the battery is charged by the output of the engine-driven generator, and reaches a full charge at a certain point. When the battery is fully charged, the engine-driven generator is stopped. According to such an apparatus configuration, the state of charge of the battery can always be maintained in a predetermined range.

[0005]

A battery mounted on an electric vehicle is, for example, a lead battery. As shown in FIG. 6, when the SOC increases, the freezing temperature _{TF of the} lead battery increases.
Has the property of decreasing. That is, when the SOC is high, the liquid inside the battery does not freeze until the temperature becomes relatively low, and conversely, when the SOC is low, the liquid may freeze even when the surrounding temperature is relatively high. . Specifically, S
In a state where the OC is about 30%, when the ambient temperature drops to −10 ° C., there is a possibility of freezing. Such a characteristic becomes a problem when the outside air temperature decreases in a state where the drive system of the electric vehicle is not moved, such as when the vehicle is parked.

An object of the present invention is to solve such a problem, and an object of the present invention is to prevent a vehicle-mounted battery from freezing when the vehicle is parked or the like.

[0007]

In order to achieve the above object, a control device according to the present invention comprises means for detecting an ambient temperature, means for detecting the SOC of a battery, and means for detecting the detected SO.
Means for determining a freezing temperature corresponding to C; means for determining whether or not the battery fluid may freeze based on the determined freezing temperature and the detected ambient temperature; Means for supplying charging power to the battery from a charging means such as an engine-driven generator when the battery is charged in advance to increase the SOC to prevent freezing of the battery liquid during parking or the like. And

Further, the control device according to the second aspect of the present invention corrects the detected ambient temperature based on a possibility of a change in the ambient temperature when determining whether there is a possibility that the liquid in the battery is frozen. Thus, the determination is made in consideration of the change in the ambient temperature.

[0009]

In the present invention, first, the ambient temperature and the SOC of the battery are detected. Next, a freezing temperature corresponding to the detected SOC is determined, and it is determined based on the determined freezing temperature and the detected ambient temperature whether or not the battery fluid may freeze. When it is determined that there is a possibility, the battery charging operation is performed, and the battery S
OC is increased. In the battery to which the present invention is applied,
The relationship between the SOC of the battery and the freezing temperature is such that the freezing temperature decreases as the SOC increases, as shown in FIG. 6, for example. When such a battery is charged by the above-described operation, the freezing temperature decreases as the SOC increases. Therefore, in the present invention, for example, when the vehicle is parked, the battery is prevented from freezing due to a low ambient temperature and a low SOC of the battery.

According to a second aspect of the present invention, when determining whether or not there is a possibility that the liquid in the battery may freeze, the detected ambient temperature is corrected based on the expected change in the ambient temperature. Will be For example, when the ambient temperature is expected to rise in the future, the ambient temperature used for the determination is corrected to be higher, and the determination is made in consideration of the change in the ambient temperature. By performing such a determination, a more accurate operation is realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the apparatus according to the first and second embodiments of the present invention. The configuration shown in this figure is a drive system of a series hybrid vehicle and its control system.

The drive system shown in FIG. 1 includes a motor 10. The motor 10 is a three-phase AC motor, and is driven by three-phase AC power supplied from an inverter 12. The inverter 12 converts DC power supplied from the main battery 14 or the engine generator 16 into three-phase AC power under the control of the vehicle ECU 18 and supplies the three-phase AC power to the motor 10. The mechanical output of the motor 10 is transmitted to the tire 24 via a transmission (T / M) 20, a differential gear (diff) 22 and the like. Thus, the driving force of the vehicle is generated.

On the other hand, the engine-driven generator 16 has an engine 26 and a generator 28. The engine 26
For example, the engine ECU 32 is controlled to rotate in a region where fuel consumption is good and emission is good. The engine 26 is connected to the generator 2 via a mechanism such as a speed increaser (not shown).
8. The generator 28 is an AC generator that rotates by the mechanical output of the engine 26, and its field current is controlled by a field controller 34. The AC output of the generator 28 is rectified by a rectifier 36 provided at a subsequent stage.

When a large amount of power is required on the motor 10 and inverter 12 side, the output cannot be satisfied only by the output power of the main battery 14, so that the rectified output of the rectifier 36 Will be used for driving. The SO of the main battery 14
When C is low, the rectified output of the rectifier 36 is used for charging the main battery 14.

Further, on the output side of the main battery 14 and the rectifier 36, a DC-DC converter 38 is provided. The DC-DC converter 38 is connected to the main battery 14 or the rectifier 3
6 are connected to different values (for example, 12
V) and converts it into a DC voltage and supplies it to onboard electrical accessories. The on-vehicle electrical accessories are, for example, members such as the vehicle ECU 18, the engine ECU 32, the field controller 34, and wipers and lamps (not shown).

The vehicle ECU 18 determines the rotational speed N of the motor 10.
, A vehicle signal indicating the amount of depression of an accelerator pedal, a brake pedal, and the like is input, and the inverter 12 is controlled based on the vehicle signal. That is, the vehicle ECU 18 controls the switching elements constituting the inverter 12 by using a PWM (pulse width modulation) signal so that the motor 10 generates an output torque corresponding to the accelerator pedal depression amount and the brake pedal depression amount. As a result, the output torque of the motor 10 becomes a torque corresponding to the value of the vehicle signal.

The vehicle ECU 18 exchanges information and commands with the engine ECU 32 and the field controller 34 while controlling the inverter 12. Engine ECU 32
Starts the engine 26 based on information supplied from the vehicle ECU 18 or in response to a command, and controls the throttle opening and the like. The field controller 34 controls the vehicle EC
The field current of the generator 28 is controlled to a predetermined value based on information supplied from U18 or according to a command. In addition,
The vehicle ECU 18 monitors the operation of the DC-DC converter 38.

In the apparatus configuration shown in FIG. 1, the operation of preventing the main battery from being frozen according to the characteristics of the present embodiment is as follows.
The vehicle ECU 18. At this time, the vehicle ECU 18 outputs the outside air temperature T, which is the output of the outside air temperature sensor 40, and the SOC meter 4
2 and the SOC of the main battery 14 and the ΔT table 4
4 is used.

FIG. 2 shows the flow of the freeze prevention operation according to the first embodiment of the present invention. The operation shown in this figure is a flow of processing of the vehicle ECU 18.

After an ignition switch (IG) (not shown) is turned off, the vehicle ECU 18 outputs an outside air temperature sensor 40
The outside air temperature T is input from (100). Next, the vehicle ECU
Numeral 18 inputs the SOC of the main battery 14 from the SOC meter 42 attached to the main battery 14 (102). Vehicle E
The CU 18 uses the main battery 1 input in step 102
Based on the SOC of 4, the freezing temperature _TF of the main battery 14 is determined (104).

That is, when a lead battery is used as the main battery 14, the SOC and the freezing temperature _TF have a relationship as shown in FIG. The vehicle ECU 18 uses this relationship to determine the freezing temperature _TF of the main battery 14 from the detected value of the SOC of the main battery 14.

The vehicle ECU 18 compares the freezing temperature _TF determined in step 104 with the outside temperature T input in step 100 (106). At that time, the vehicle E
The CU 18 corrects the outside air temperature T by a correction term ΔT. The correction term ΔT is information in consideration of a daily change of the outside air temperature T, a rapid cooling, and the like, that is, an estimated amount of the temperature change. The ΔT table 44 on the ROM or the backed-up RAM contains information for associating information such as latitude, longitude, altitude, date, time and the like with the correction term ΔT.
That is, the correction term ΔT is determined based on the position of the vehicle,
It is determined based on the current date and time. Vehicle ECU 18
Calculates the correction term ΔT in the ΔT table 4 shown in FIG.
4 is determined. In this example, the correction term ΔT
Is positive, a correction is made to allow for a temperature drop, and if negative, a correction is made to subtract the correction term ΔT from the outside air temperature T so that a correction is made to allow for a temperature rise. Correction term ΔT
May be set manually or input from an external device.

As described above, as a result of step 106 executed as a determination as to whether or not the freezing temperature _TF is equal to or higher than the corrected outside air temperature T-ΔT, if the former is determined to be equal to or higher than the latter, If the main battery 14 is left as it is, there is a possibility that the main battery 14 may be frozen. The vehicle ECU 18
When such a determination result is obtained, the engine ECU 3
And a command to the field controller 34 and the engine 2
6 and the generator 28 are started (108). Step 1
After execution of step 08, the process returns to step 100 and the above-described operation is repeated.

If it is determined in step 106 that the freezing temperature _TF is lower than the corrected outside air temperature T-ΔT, it is determined that there is no possibility that the main battery 14 will freeze even if the vehicle is left unattended. Can be. Therefore, the vehicle ECU 18
A command is given to the engine ECU 32 and the field controller 34 to stop the operation of the engine 26 and the generator 28 (110). After executing step 110, the vehicle ECU 18 executes various contactors (not shown) (for example, the inverter 1).
A termination work such as turning off a contactor provided in the preceding stage of Step 2 is performed (112).

As described above, according to the present embodiment, the outside air temperature T
In addition, since the SOC of the main battery 14 is detected and the engine 26 and the generator 28 are operated as necessary based on the detection result, the SOC of the rechargeable battery 14 is improved to an SOC that does not cause freezing. be able to. As a result, problems such as damage to the main battery 14 due to freezing are prevented.

Further, when determining whether there is a possibility of freezing of the main battery 14, that is, when executing step 106, an external correction term ΔT determined in accordance with the current position of the vehicle, the current date and time, and the like is used. Since the temperature T is corrected, it is possible to determine the possibility of freezing while anticipating a decrease or increase in the outside temperature T from the current time. Accordingly, the operation of preventing the main battery 14 from being frozen can be more suitably performed, and more accurate control can be realized.

In addition, in this embodiment, after the ignition switch is turned off, the main battery 14
, The device for keeping the main battery 14 warm and heated can be simplified. As a result, the vehicle weight can be reduced, and the power performance can be improved.

FIG. 3 shows an operation flow according to the second embodiment of the present invention. The operation shown in FIG.
Similar to the above, the operation of the vehicle ECU 18 is performed.

This embodiment differs from the first embodiment shown in FIG. 2 in that step 114 is executed before step 106 is executed. In step 114, it is determined whether or not the freezing temperature _TF obtained in step 104 is equal to or higher than the outside temperature T before correction. If this determination is made, step 108 is immediately executed.
Is executed, and if it is not established, the process proceeds to step 106.

Therefore, in this embodiment, the outside air temperature T
Is slightly lower than the freezing temperature T _{F, the} correction is performed by the correction term ΔT having a negative value, and the condition of step 106 is not satisfied by the correction, the engine 26 and the generator 28 operate. I do. As a result, the main battery 14 is less likely to freeze.

FIG. 4 shows the configuration of an apparatus according to a third embodiment of the present invention. In this figure, DC-DC
A power supply system from the converter 38 to the on-vehicle electric auxiliary machine is shown. That is, the DC-DC converter 38
An auxiliary battery 46 is connected to the output side of the vehicle EC.
U18, engine ECU 32 and field controller 34
The DC-DC converter 38 and the auxiliary battery 4
For example, a DC voltage of 12 V is supplied from 6.

This embodiment is characterized in that an SOC meter 48 is also provided for the auxiliary battery 46 and the vehicle ECU
18 is an auxiliary battery 4 based on the output of the SOC meter 48.
6 is performed as needed. FIG. 5 shows a flow of the operation of the vehicle ECU 18 in this embodiment.

As shown in FIG.
Executes steps 100 to 106 as in the first embodiment. When it is determined in step 106 that _TF ≧ T−ΔT, the process proceeds to step 108 as in the first embodiment,
The operation after step 100 is repeated. Step 1
If this condition is not satisfied in 06, vehicle ECU 18 executes steps 116 to 120.

In step 116, vehicle ECU 1
Reference numeral 8 denotes an auxiliary battery 4 from the SOC meter 48 on the auxiliary battery 46 side.
6 is input, and in step 118 this S
The freezing temperature T _F ′ of the auxiliary battery 46 is determined based on the OC. In step 120, the vehicle ECU 18 performs the determination related to the freezing temperature T _F ′ as in step 106. As a result of this determination, the freezing temperature T _F ′ of the auxiliary battery 46
Is determined to be equal to or higher than the corrected outside air temperature T-ΔT, that is, if it is determined that the auxiliary battery 46 has a possibility of freezing, step 108 is executed, and the auxiliary battery 46 -Is charged via the DC converter 38;
If this determination is not made in step 120, that is, the auxiliary battery 4
If it is determined that No. 6 does not freeze, step 110
And 112. In step 112, contactor 50 provided between main battery 14 and DC-DC converter 38 is turned off by vehicle ECU 18 together with another contactor (not shown).

Therefore, according to this embodiment, when the end work (112) is executed, the auxiliary battery 46
In a device configuration in which the power supply path to the battery is opened (for example, the contactor 50 is turned off), the auxiliary battery 46 can be prevented from freezing.

That is, in the device configuration shown in FIG. 1, the output of the main battery 14 is always the DC-DC converter 38.
Is connected to the input side. Therefore, the auxiliary battery 46 (not shown) is connected to the main battery 1 via the DC-DC converter 38.
4 or the output of the engine-driven generator 16 is always in a chargeable state. The auxiliary battery 46 is usually
Although it is configured as a lead battery like the main battery 14, it can be charged more quickly than the main battery 14 because of its small capacity. Therefore, in the configuration shown in FIG. 1, by executing the operation shown in FIG. 2 or FIG. 3, that is, the anti-freezing operation by charging the main battery 14, it is possible to simultaneously prevent the auxiliary battery 46 from being frozen. Can be.

On the other hand, in the apparatus configuration as shown in FIG. 4, once the end operation (112) is executed, the auxiliary battery 46 cannot be charged. Therefore,
If the ignition is turned off in a state where the SOC of the main battery 14 has not decreased but the SOC of the auxiliary battery 46 has decreased, step 11 is performed in a state where the SOC of the auxiliary battery 46 is low.
0 and 112 are executed, and in some cases, the auxiliary battery 46 may freeze. The operation shown in FIG. 5 enables the auxiliary battery 46 to be prevented from freezing even in the device configuration shown in FIG.

As described above, according to the present embodiment, the possibility of freezing of the auxiliary battery 46 can be reduced even in the apparatus configuration shown in FIG.

In the above description, the main battery 14 and the auxiliary battery 46 are treated as separate components. However, the present invention is also applicable to a case where the auxiliary battery 46 is configured as a part of the main battery 14, for example. . That is, the main battery 14 is usually configured by connecting a plurality of elements in series, and some of the elements can be used as the auxiliary battery 46. However, the present invention can be applied to such a configuration. Thus, freezing of both the main battery 14 and the auxiliary battery 46 can be prevented.

In the above description, the main battery 14 and the auxiliary battery 46 have been described as lead batteries, but the present invention is not limited to lead batteries. That is, the present invention can be applied to any type of battery as long as the battery has a characteristic that the freezing temperature _TF increases when the SOC decreases.

In addition, in the third embodiment, step 12
Although the step 108 is executed when the condition of 0 is satisfied, the charging may be performed by the output of the main battery 14 without operating the engine 26 and the generator 28.

[0043]

As described above, according to the present invention,
Whether the vehicle-mounted battery is likely to freeze is determined based on the detected ambient temperature and the detected freezing temperature based on the detected SOC, and the battery is charged if the possibility exists. Freezing of the battery can be suitably prevented when the vehicle is parked or the like. As a result, it is possible to preferably prevent the occurrence of troubles such as damage to the battery.

According to the second aspect of the present invention, the detected ambient temperature is corrected on the basis of the expected change in the ambient temperature, so that it is possible to determine whether or not the battery fluid may freeze. It can be executed precisely, and the effect according to the present invention can be made more remarkable. In addition, since the setting can be made based on the expected change used for the correction, the current position of the vehicle, the current date and time, more precise control according to the current position and the current date and time can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus according to first and second embodiments of the present invention.

FIG. 2 is a flowchart showing a flow of an operation of a vehicle ECU according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating a flow of an operation of a vehicle ECU according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an apparatus according to a third embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of an operation of the vehicle ECU in the embodiment.

FIG. 6 is a diagram showing the relationship between the SOC of the battery and the freezing temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Motor 12 Inverter 14 Main battery 16 Engine drive generator 18 Vehicle ECU 26 Engine 28 Generator 32 Engine ECU 34 Field controller 38 DC-DC converter 40 Outside air temperature sensor 42, 48 SOC meter 44 ΔT table 46 Auxiliary battery 50 Contactor T Outside temperature SOC State of charge _TF Freezing temperature of main battery _TF ′ Freezing temperature of auxiliary battery ΔT Correction term of outside temperature

Claims (2)

(57) [Claims] 1. An on-vehicle battery that has a liquid therein and whose freezing temperature decreases as the state of charge increases, and is mounted on an electric vehicle that has on-vehicle charging means for charging the battery. A control unit for controlling the supply of charging power, a unit for detecting an ambient temperature, a unit for detecting a state of charge of the battery, a unit for obtaining a freezing temperature corresponding to the detected state of charge, Means for determining whether or not the battery liquid may freeze based on the detected ambient temperature; and means for supplying charging power to the battery from the charging means when the possibility is determined. A control device, comprising: charging in advance to increase a state of charge to prevent freezing of a battery liquid during parking or the like. 2. The control device according to claim 1, wherein, when determining whether there is a possibility that the liquid in the battery is frozen, the detected ambient temperature is corrected based on an estimated change in the ambient temperature. A control device for performing the determination in consideration of a change in ambient temperature.