JP2003274502A - Power input control circuit for vehicule electric system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress overheating of a circuit or peripheral components thereof caused by frequent power input operations, in a vehicule electric system. <P>SOLUTION: A power input determining section 14 obtains the hydraulic fluid temperature change from the temperature of the hydraulic fluid detected at a prescribed timing by a hydraulic temperature sensor 16, and determines whether to input power based on the temperature change. When the power input determining section 14 determines that power can be input, it outputs a control signal for power input, in other words, closing a subrelay 54; while if it determines that power cannot be input, it does not immediately perform power input, but inputs power after waiting for a prescribed period of time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for controlling power-on of an electric system such as a vehicle drive motor control system mounted on a vehicle, and more particularly to suppressing a temperature rise of a circuit of the electric system or its peripheral parts. About possible technology.

[0002]

2. Description of the Related Art FIG. 5 shows a main power supply circuit 40 of an electromotive force control system for a drive motor of an electric vehicle. The main power supply circuit 40 shown in FIG. 5 is a power supply battery 4 configured as an assembled battery.
2, a storage battery 44 capable of storing the electric power from the power supply battery 42,
A main connection path 48 connecting the power battery 42 and the storage battery 44,
A main relay 50 that opens and closes the main connection path 48, a bypass path 52 that bypasses the main relay 50, and a bypass path 52.
A sub-relay 54 for opening and closing, and a resistor 56 also provided in series with the sub-relay 54 in the bypass path 52,
including.

The capacitor 44 has a load 58 connected to it.
It has a function of reducing voltage fluctuations in a DC / DC converter, an inverter, a drive motor, etc.
At the beginning of use of the drive motor, the storage battery 44
Receives electric power from the power supply battery 42 and stores electric charge.
The power supply at this time is performed via the main connection path 48 or the bypass path 52. Sub relay 54, resistor 56,
The bypass path 52 cooperates with the main relay 50 and has a function of suppressing an excessive current supply to the main relay 50 at the start of power supply (particularly at the beginning of power supply), and is referred to as a precharge circuit 60. It

Now, the operation and action of the conventional precharge circuit 60 will be described with reference to FIG. Figure 6
Indicates the change over time of the current Ip (FIG. 5) supplied to the battery 44 at the beginning of power supply, the horizontal axis indicates time, and the vertical axis indicates current value. Further, in FIG. 6, the broken line indicates that power is supplied from the power supply battery 42 to the storage battery 44 only by the main connection path 48 without the precharge circuit 60 (this is because the main relay 50 remains open when the sub relay 54 remains open).
Corresponding to the case of closing the current Ip), and the solid line is used with the precharge circuit 60, that is, by the main connecting path 48 and the bypass path 52.
2 shows a change over time in the current Ip when electric power is supplied from 2 to the battery 44.

When electric power is supplied from the power source battery 42 to the battery 44 by only the main connecting path 48, the main relay 5
When 0 is closed, the current Ip rises sharply, and a very large current (rush current) flows through the main connecting path 48 including the main relay 50. In this case, the fuse may be blown or the main relay 50 (for example, the electrode portion thereof) may be damaged.

In order to avoid such a problem, a precharge circuit 60 is conventionally provided in this type of circuit. The precharge circuit 60 functions as a power supply path before power is supplied by the main connection path 48. In this circuit, the sub relay 54 is first closed before the main relay 50 is closed (that is, in the state where the main relay 50 is open). Then, the power from the power supply battery 42 is supplied through the precharge circuit 60. At this time, the resistor 56 provided in the precharge circuit 60 suppresses an increase in the current value Ip as compared with the conventional case as shown by the solid line in FIG. 6 (the maximum value of the current Ip at this time is shown in FIG. 6). Ip1). Then, when the current Ip becomes sufficiently small, the main relay 50 is closed. Then,
Since the electric power is already stored in the storage battery 44 through the precharge circuit 60, the increase in the current Ip is suppressed (the maximum value of the current Ip at this time is Ip2 in FIG. 6). As for the sub relay 54, the main relay 50 is the main connection path 4
After closing 8, open the bypass.

[0007]

In the precharge circuit 60, the current value Ip corresponding to the power loss due to the resistor 56 is generated.
Rise is suppressed. This power loss is due to resistor 56
At that time, electric power is converted into heat energy. For this reason, the temperature of the resistor 56 and its peripheral components increases every time the precharge, that is, the current is applied to the resistor 56. Normally, the precharge circuit 60
Are opened after the end of precharging, and the energization of the resistor 56 is stopped, so that they are cooled by the surrounding environment with the lapse of time, and their temperatures gradually decrease. However, if the operator frequently gives a power-on instruction (for example, an ignition key ON operation) for some reason, and the sub-relay 54 is opened / closed, that is, the resistor 56 is frequently energized in accordance with the instruction, Since a sufficient cooling period cannot be taken, the temperature rise of the resistor 56 and its peripheral components becomes large, which is not preferable from the viewpoint of ensuring performance in the precharge circuit 60, the main power supply circuit 40, other peripheral circuits or peripheral components. There was a case where it ended up.

[0008]

A power-on control circuit for an electric system for a vehicle according to the present invention includes a temperature change acquisition means for acquiring a temperature change of a working fluid for a vehicle, and a power-on instruction signal when the power-on instruction signal is acquired. And a power-on / no-on determination means for determining whether to turn on the power of the vehicle electrical system based on the temperature change.

Here, the vehicle hydraulic fluid is a fluid used for traveling of the vehicle or driving of a drive system such as an engine or a motor, for example, for transmission of energy, lubrication of sliding parts, etc., and the ambient temperature during use. It is desirable for the liquid to rise to a higher temperature. Suitable working fluids are, for example, radiator cooling water, engine oil, motor oil, and the like. The temperatures of these hydraulic fluids change with time. For example, when the system in which the hydraulic fluid is used stops operating, the temperature of the hydraulic fluid gradually decreases from the temperature during operation due to cooling by the surrounding environment. That is, if the temperature change characteristic of the hydraulic fluid is acquired in advance, the elapsed time can be estimated from the temperature change. The power-on control circuit according to the present invention realizes power-on control according to the frequency of power-on (time interval of power-on) by utilizing the time-dependent characteristic of the working fluid temperature. More specifically, for example, when the power-on control circuit can determine from the temperature change of the hydraulic fluid that the time sufficient for cooling the circuit element or its peripheral parts has not elapsed since the previous power-on, , Even if the next power-on instruction is issued, the power is not turned on. Conversely, if it can be determined that the time sufficient for cooling has passed since the previous power-on, the power is turned on according to the power-on instruction. Input. As the temperature change used as an index for determining whether or not the power can be turned on, for example, a temperature difference in a predetermined time, a temperature change rate per unit time, or the like can be used.

Further, in the power-on control circuit according to the present invention, the temperature change acquisition means includes the temperature of the vehicle hydraulic fluid acquired at the timing corresponding to the power-on period,
It is preferable to acquire the temperature change as a temperature difference between the temperature of the vehicle hydraulic fluid acquired in response to the next power-on instruction. The timing corresponding to the power-on period means the timing before the substantial temperature change of the hydraulic fluid is started after the power is turned off, and includes the timing during the period when the power is on and immediately after the power is turned on. ,
The timing is preferably when the power is turned off or immediately before that.

The power-on control circuit according to the present invention further comprises storage means for storing power-on / no-go determination information indicating whether power can be turned on with respect to a change in temperature of the vehicle hydraulic fluid. It is preferable to determine whether or not the power is turned on with reference to the availability determination information. This makes it possible to determine whether or not the power can be turned on more easily and more accurately.

In the power-on control circuit according to the present invention, the storage means stores a plurality of different power-on / no-go determination information, and the power-on / no-power determination means, based on the environmental temperature of the vehicle working fluid, It is preferable to select the input availability determination information to be referred to. The temperature change of the hydraulic fluid for vehicles is
Depends on the temperature of the surrounding environment. For example, when the temperature of the ambient environment is high (for example, in summer), the temperature drop of the hydraulic fluid is more gradual, and when the temperature of the ambient environment is low (for example, in winter), the temperature drop of the hydraulic fluid is faster than that in summer. Is. Therefore, it is possible to more accurately determine whether the power can be turned on by selecting the turn-on / off determination information that is more suitable for the ambient temperature.

Further, in the power-on control circuit according to the present invention, it is preferable that the power-on / no-on determination means determines whether or not the power can be turned on based on temperature changes of a plurality of different vehicle hydraulic fluids. By doing this,
It is possible to more accurately determine whether power can be turned on.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A power-on control circuit for an electric system for a vehicle according to an embodiment of the present invention will be described below with reference to the drawings. The power-on control circuit 10 according to the present embodiment is configured as a power-on control circuit of the electromotive force control system for a drive motor of an electric vehicle shown in FIG. FIG. 1 is a block diagram showing a main power supply circuit 40 of an electromotive force control system for a drive motor of an electric vehicle and a power-on control circuit 10 for controlling power-on of the main power supply circuit 40. FIG. It is a figure which shows the time-dependent change of temperature.

As shown in FIG. 1, the main power supply circuit 40 has a structure similar to that shown in FIG. 5, and operates as described above. Therefore, detailed description of the main power supply circuit 40 itself is omitted.

Power-on control circuit (eg ECU) 10
Is an ignition key 12 as a power-on instruction means.
A power-on availability determination unit 14 that obtains a power-on instruction signal from (IGN) and uses the signal as a trigger to determine power-on availability. The power-on availability determination unit 14 acquires the temperature change of the hydraulic fluid from the temperature of the hydraulic fluid detected by the hydraulic fluid temperature sensor 16 at a predetermined timing, and determines the power availability based on the temperature change. When it is determined that the power can be turned on based on the temperature change, the power-on availability determination unit 14 outputs a control signal for executing the power-on operation, that is, the closing operation of the sub-relay 54, and on the other hand, determines that the power-on is impossible. In that case, the power-on operation is not performed immediately, but the power-on operation is executed after waiting for a predetermined time. This waiting time may be a predetermined fixed time or may be variably set according to the acquired temperature change (for example, the waiting time becomes longer as the temperature change increases). In this case, since the standby time is variably set, the storage unit 20 may store information indicating the standby time corresponding to each value of the temperature change.

The storage unit 20 stores a plurality of turn-on / off determination information 18 indicating whether or not the power can be turned on with respect to a temperature change. Here, the number (for example, two) of the supply possibility determination information 18 corresponding to the environmental temperature is stored for each of the plurality of hydraulic fluids. Then, the power-on availability determination unit 14 determines the power-on availability for each of the plurality of hydraulic fluids with reference to the power-on availability determination information 18, and determines the power on-ability based on the results. For example, the determination result of whether or not the power can be turned on is obtained for each of the odd-numbered types of hydraulic fluid, and the one with the larger number of the acceptable and the ineffective is adopted as the determination result.

Discrimination information 1 on whether or not to input the information, which is referred to in the discrimination.
8 is selected based on the environmental temperature acquired from the environmental temperature sensor (for example, the outside air temperature sensor) 22. For example, when a plurality of charging possibility determination information 18 are stored according to the environmental temperature range, the charging permission determination information 18 is selected depending on which environmental temperature range the environmental temperature with respect to the predetermined temperature is.

Here, an example of the change with time of the working fluid temperature will be described with reference to FIG. In the summer (solid line), the temperature of the working fluid decreases gradually due to the high environmental temperature. In winter (broken line), the low environmental temperature causes
The hydraulic fluid temperature drops more rapidly than in summer. As is clear from FIG. 2, the difference in temperature at the same time is as follows:
It becomes larger in winter, and the amount of temperature change per unit time also becomes larger in winter. As described above, since the temperature change characteristics of the hydraulic fluid differ depending on the environmental temperature, by using the determination criterion (that is, the power availability determination information 18) that is more suitable for the ambient temperature, it is possible to more accurately determine whether power can be turned on. .

Next, with reference to FIG. 3, an example of a more specific operation of power-on control by the power-on control circuit 10 will be described. FIG. 3 is a flowchart showing an example of power-on control by the power-on control circuit 10.

When the power-on control circuit 10 receives a power-off instruction signal from the ignition key 12 (step S10), it obtains the temperature of the hydraulic fluid (hereinafter referred to as the power-off temperature Te) from the hydraulic fluid temperature sensor 16. Then, this is stored in the storage unit 20 (step S12), and the power-off operation is executed (step S14). Here, the temperature T at power-off
e corresponds to the temperature of the hydraulic fluid acquired at the timing corresponding to the power-on period.

Thereafter, when the power-on control circuit 10 receives a power-on instruction signal from the ignition key 12 (step S16), first, the temperature of the hydraulic fluid from the hydraulic fluid temperature sensor 16 (hereinafter referred to as the power-on instruction temperature Ts Note)
Is acquired and stored in the storage unit 20 (step S1).
8). Next, the power-on control circuit 10 acquires the environmental temperature from the environmental temperature sensor 22 (step S20), and determines the power-on / no-go discrimination information 18 to be referred to based on the environmental temperature (step S22). Next, the power-on control circuit 10 acquires the power-off temperature Te and the power-on instruction temperature Ts from the storage unit 20, and as a temperature change between them, a temperature difference ΔT1 (that is, the difference between Te and Ts or its absolute value). Value) is calculated (step S24). Next, the power-on control circuit 10 compares the calculated temperature difference ΔT1 with the threshold Th1 for determining whether or not the power-on / no-go is included in the power-on / no-go determination information 18 to determine whether to turn on the power. For example, when the temperature difference ΔT1 is equal to or larger than the threshold Th1, it is determined that the power can be turned on,
When the temperature difference ΔT1 is lower than the threshold Th1, it is determined that the power cannot be turned on (step S26). Then, the power-on control described above is executed based on the result of the determination (step S28). In this case, the threshold value Th1 is set as a temperature difference corresponding to the elapsed time required for the temperature of the heat generating element of the circuit and its peripheral components to decrease to the minimum required time, since the elapsed time from the previous power-on period is long. It Therefore, when the temperature difference ΔT1 is smaller than the threshold value Th1, that is, when the time elapsed from the previous power-on period is short, power-on is restricted, and overheating of the circuit and its peripheral components due to frequent power-on is suppressed.

Next, another example of a more specific operation of the power-on control by the power-on control circuit 10 will be described with reference to FIG. FIG. 4 is a flowchart showing another example of power-on control by the power-on control circuit 10.

In the example of FIG. 3, the power-on control circuit 10 is
The temperature change was acquired as the temperature difference between the temperature of the hydraulic fluid at the timing corresponding to the previous power-on period (that is, the power-off temperature Te) and the power-on instruction temperature Ts.
In the above example, the temperature difference per predetermined time at the time of power-on instruction is acquired as the temperature change which is the basis for determining whether to turn on the power. Therefore, in this example, it is not necessary to store the data acquired during the previous power-on period.

As shown in FIG. 4, the power-on control circuit 10
When receiving the power-on instruction signal from the ignition key 12 (step S40), first, the temperature of the hydraulic fluid from the hydraulic fluid temperature sensor 16 (hereinafter, the temperature acquired at this timing is referred to as the first temperature Ts1) is detected. It is acquired and stored in the storage unit 20 (step S42). Further, the power-on control circuit 10 acquires the environmental temperature from the environmental temperature sensor 22 (step S44), and determines the power-on / no-go determination information 18 to be referred to based on the environmental temperature (step S4).
6). Next, the power-on control circuit 10 determines the timing at which the temperature of the hydraulic fluid was acquired last time (that is, the first temperature Ts1).
(Predetermined time Δ)
The temperature of the hydraulic fluid at the timing when t has elapsed (hereinafter, this temperature is referred to as the second temperature Ts2) is acquired and stored in the storage unit 20 (step S48). Next, the power-on control circuit 10 reads the first temperature Ts1 from the storage unit 20.
And the second temperature Ts2 are acquired, and their difference ΔT2
(That is, the difference between Ts1 and Ts2 or its absolute value)
The temperature change is calculated as (step S50). Next, the power-on control circuit 10 calculates the temperature difference ΔT2 and the threshold Th2 for determining whether or not the temperature is included in the power-on / no-go determination information 18.
Is compared to determine whether or not the power can be turned on. For example, when the temperature difference ΔT2 is equal to or larger than the threshold Th2, it is determined that the power cannot be turned on, and when the temperature difference ΔT2 is lower than the threshold Th2, it is determined that the power can be turned on (step S52). And
The power-on control described above is executed based on the result of the determination (step S54).

It should be noted here that the temperature difference ΔT2 in the example of FIG. 4 is an amount proportional to the amount of temperature change per unit time. As can be seen from FIG. 2, the amount of temperature change per unit time (that is, the absolute value of the slope of the graph in FIG. 2) decreases with the passage of time. Using this characteristic, in the example of FIG. 4, the temperature difference ΔT2 per predetermined time
The elapsed time is estimated from. Therefore, the threshold Th
2 is the temperature change rate (that is, the predetermined time Δ) corresponding to the elapsed time required for the temperature of the heat-generating element of the circuit and its peripheral components to decrease to the minimum necessary temperature from the previous power-on period.
The amount of temperature change per t) is set. Then, when the temperature difference ΔT2 is larger than the threshold value Th2, that is, when the elapsed time from the previous power-on period is short, power-on is regulated, and overheating of the circuit and its peripheral components due to frequent power-on is suppressed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the power-on control circuit according to the present invention is not limited to a precharge circuit including a resistor, but includes a component whose operation / stop is switched by a power-on instruction and which causes overheating due to frequent power-on. It can be applied to a circuit. Also, as the input availability determination information,
It is also possible to use a flag (for example, power can be turned on: 1, power cannot be turned on: 0) indicating whether or not the temperature difference (for example, ΔT1 and ΔT2 described above) is determined.

[0028]

As described above, according to the present invention,
Overheating of the circuit or its peripheral parts due to frequent power-on is suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power-on control circuit according to an embodiment of the present invention.

FIG. 2 is a graph showing changes over time in the temperature of the vehicle hydraulic fluid during summer and winter.

FIG. 3 is a flowchart showing an example of the operation of the power-on control circuit according to the embodiment of the present invention.

FIG. 4 is a flowchart showing another example of the operation of the power-on control circuit according to the embodiment of the present invention.

FIG. 5 is a configuration diagram of a main power supply circuit of a conventional electromotive force control system for a drive motor of an electric vehicle.

FIG. 6 is a diagram showing a change with time of a current flowing into a capacitor of the conventional main power supply circuit shown in FIG.

[Explanation of symbols]

10 power-on control circuit, 12 ignition key,
14 power-on / no-power determination unit, 16 hydraulic fluid temperature sensor,
18 input permission / prohibition determination information, 20 storage unit, 22 environment temperature sensor, 40 main power circuit, 42 power battery, 44 battery, 48 main connection path, 50 main relay, 52 bypass path, 54 sub relay, 56 resistor, 58 load,
60 Precharge circuit.

Claims (6)

[Claims] 1. A temperature change acquisition means for acquiring a temperature change of a hydraulic fluid for a vehicle, and a power supply enable / disable determination for determining whether or not the power supply of a vehicle electrical system can be turned on based on the temperature change by acquiring a power supply instruction signal. And a power-on control circuit for the electric system for the vehicle, which comprises: 2. The temperature change acquisition means, the temperature of the vehicle hydraulic fluid acquired at the timing corresponding to the power-on period, and the temperature of the vehicle hydraulic fluid acquired in response to the next power-on instruction. 2. The power-on control circuit according to claim 1, wherein the temperature change is obtained as a temperature difference between 3. A storage means for storing power-on availability determination information indicating whether power-on is possible with respect to a temperature change of the vehicle hydraulic fluid, wherein the power-on availability determination means refers to the power-on availability determination information to power on. The power-on control circuit according to claim 1 or 2, which determines whether or not 4. The storage means stores a plurality of different thrown-on / no-go determination information, and the power-on / no-go determination means selects the thrown-on / no-go determination information to be referred to based on the environmental temperature of the vehicle hydraulic fluid. The power-on control circuit according to claim 3, wherein. 5. The power supply according to any one of claims 1 to 4, wherein the power-on / no-power determination unit determines whether or not the power can be turned on based on temperature changes of a plurality of different vehicle hydraulic fluids. Closing control circuit. 6. An electric system for a vehicle whose power-on is controlled by the power-on control circuit according to any one of claims 1 to 5.