JP5326298B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to an in-vehicle battery that is charged by electric power generated by an in-vehicle generator in conjunction with an engine, electric power discharged from the in-vehicle battery, and plural for supplying electric power generated by the in-vehicle generator to each of a plurality of loads. The present invention relates to a vehicular power supply device including the switch circuit.

In the vehicle power supply device, when the power generated by the in-vehicle generator linked to the engine is supplied to each load mounted on the vehicle and charged to the in-vehicle battery, the power generated by the in-vehicle generator is insufficient, or When the engine is stopped, power is supplied from the in-vehicle battery to each load.
The number of electrical components (loads) mounted on vehicles is increasing steadily from the aspects of safety, convenience, comfort, and product power. Large-capacity electric loads such as wind defoggers and seat heaters for cold regions are adopted, and equipment that has been operated with hydraulic pressure or engine power is electrified to improve control performance and efficiency. Therefore, the importance of the power supply device for vehicles is increasing, and the number of electric wires (wire harnesses) for supplying power to each electrical component is increasing.

Patent Document 1 includes a main power switch for connecting an electric load and a DC power source, and an inrush current limiting circuit connected in parallel with the main power switch, and the inrush current limiting circuit is conducted before the main power switch. An inrush current limiting type power switch for a vehicle having a sub power switch and an inrush current limiting resistor connected in series with the sub power switch is disclosed. It comprises a diode connected in series with an inrush current limiting resistor in the forward direction, and determines whether or not the current value flowing through the diode exceeds a predetermined value when the main power switch and the sub power switch are off, When it is determined that it has exceeded, it is determined that the sub power switch has failed.
JP 2005-339470 A

Some loads mounted on vehicles have inductance, such as motors, and are low resistance when the filament is cold, and high resistance when the filament is red hot. There is such a load. In these loads, when the power switch is turned on and a current begins to flow, an excessive inrush current instantaneously flows. For this reason, as shown in FIG. 6 (a), when an inrush current C flows, the power supply voltage D drops momentarily. When this voltage drop is large, an ECU (Electronic Control) built in the vehicle and incorporating a microcomputer is used. Unit) etc. have a problem of malfunction.
In addition, when the number of electric wires (wire harnesses) that supply electric power to each electrical component increases, there is a problem that the weight and accommodation space cannot be ignored.

  The present invention has been made in view of the circumstances as described above, and can suppress inrush current when starting a load mounted on a vehicle, the power supply voltage does not decrease, and the weight of the electric wire and the accommodation space can be reduced. An object of the present invention is to provide a vehicular power supply device that can be reduced.

According to a first aspect of the present invention, there is provided a vehicular power supply device that includes a plurality of in-vehicle batteries that are charged by electric power generated by an in-vehicle generator in conjunction with an engine, electric power discharged from the in-vehicle battery, and electric power generated by the in-vehicle generator. In a vehicle power supply device comprising a plurality of switch circuits for supplying to each of the loads, a detection means for detecting a current value flowing through the switch circuit when the switch circuit is on, and the detection means Determining means for determining whether or not the determined current value is greater than or equal to a predetermined current value, and off means for turning off the switch circuit for a predetermined time when the determination means determines that the current value is greater than or equal to the predetermined current value. The switch circuit is a semiconductor relay having a current detection function, and the determination means determines whether or not the current value detected by the current detection function is equal to or greater than a predetermined current value. The semiconductor relay includes: a first switching element that turns on / off a current flowing through a load; a second switching element that turns on / off similarly to the first switching element; and the second switching element A current limiting circuit that limits the current flowing through the first switching element according to the current flowing through the first switching element, and a series circuit having a resistance through which the current that is limited by the current limiting circuit flows. circuit is connected in parallel, based on the voltage across the resistor, and configured characterized tare Rukoto to detect a current flowing through the first switching element.

In this vehicle power supply device, the in-vehicle battery is charged by the electric power generated by the in-vehicle generator in conjunction with the engine, and the plurality of switch circuits respectively supply the discharge power of the in-vehicle battery and the generated power of the in-vehicle generator to a plurality of loads. To supply. When the switch circuit is on, the detection means detects a current value flowing through the switch circuit, and the determination means determines whether or not the detected current value is equal to or greater than a predetermined current value. The off means turns off the switch circuit for a predetermined time when the determination means determines that the current value is equal to or greater than the predetermined current value.
The switch circuit is a semiconductor relay having a current detection function, and the determination unit determines whether or not the current value detected by the current detection function is equal to or greater than a predetermined current value.
In the semiconductor relay, the first switching element turns on / off the current flowing through the load. In the series circuit connected in parallel with the first switching element, the second switching element is turned on / off in the same manner as the first switching element, and the current limiting circuit supplies the current flowing through the second switching element to the first switching element. The current is limited according to the flowing current, and the limited current flows to the resistor. Based on the voltage across this resistor, the current flowing through the first switching element is detected.

According to a second aspect of the present invention, there is provided a vehicular power supply apparatus configured to turn off the switch circuit when the off means repeatedly performs the operation of turning off the switch circuit for a predetermined time for a predetermined number of times or a predetermined time. It is characterized by being.

  In this vehicular power supply device, the switch circuit is turned off when the turning-off means repeatedly performs the operation of turning the switch circuit off for a predetermined time for a predetermined number of times or a predetermined time.

The vehicle power supply device according to a third aspect is characterized in that the predetermined current value for each of the switch circuits is determined so as to change based on an elapsed time since the switch circuit is turned on.

  In this vehicle power supply device, the predetermined current value for each switch circuit changes based on the elapsed time since the switch circuit was turned on.

According to a fourth aspect of the present invention, there is provided a vehicular power supply apparatus, wherein the electric wire connecting the switch circuit and the load has a current value that flows until the electric wire smokes and a smoke generation characteristic that is determined by a flow time of the current more than a predetermined current value of the switch circuit. It is characterized by being.

  In this vehicle power supply device, the electric wire connected between the switch circuit and the load has a current value that flows until the electric wire smokes and a smoke generation characteristic that is determined by the flow time is equal to or greater than a predetermined current value of the switch circuit.

  According to the vehicle power supply device of the present invention, when starting a load mounted on the vehicle, the inrush current can be suppressed, the power supply voltage does not decrease, and the weight of the electric wire and the accommodation space can be reduced. Can be realized with a simple configuration.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a vehicle power supply device according to the present invention.
In this vehicular power supply device, an alternator (on-vehicle generator, AC generator) 1 generates power in conjunction with the engine 15. The electric power generated by the alternator 1 is rectified in the alternator 1 and then charged to the in-vehicle battery 4 through the fuse F0 in the relay box 11.
The voltage acquisition means 5 in the power supply ECU (Electronic Control Unit) 12 acquires the input / output voltage value of the in-vehicle battery 4.

  The output voltage of the alternator 1 and the output voltage of the in-vehicle battery 4 are supplied to the electric load 8 through the semiconductor relay (IPS; Intelligent Power Switch) 6, to the electric load 9 through the semiconductor relay 7, and to the electric load 10 through the semiconductor relay 13, for example. Each is applied. The output voltage of the alternator 1 and the output voltage of the in-vehicle battery 4 are also applied to other electric loads through the respective semiconductor relays.

The semiconductor relays 6, 7, 13 are operated by respective switches 6S, 7S, 13S. Each on / off signal by the switches 6S, 7S, 13S is given to the power supply ECU 12, and the power supply ECU 12 turns on / off the semiconductor relays 6, 7, 13 in accordance with the given on / off signals.
The semiconductor relays 6, 7, and 13 provide the power supply ECU 12 with a voltage corresponding to the flowing current. The power supply ECU 12 detects the value of current flowing through each of the semiconductor relays 6, 7, 13 based on the voltage applied from each of the semiconductor relays 6, 7, 13. The power supply ECU 12 stores a predetermined current value for turning off the semiconductor relays 6, 7, 13 for a predetermined time when the current value flowing through the semiconductor relays 6, 7, 13 is equal to or greater than that value. Is recorded.

  In the vehicle power supply device shown in FIG. 1, the current detection function of the semiconductor relays 6, 7, and 13 is used to omit the fuses for the electric loads 8, 9, and 10. As shown, fuses F1, F2, and F3 may be provided on the alternator 1 and the in-vehicle battery 4 side of the semiconductor relays 6, 7, and 13, respectively. By providing the fuses F1, F2, and F3, it is possible to prepare for the case where the semiconductor relays 6, 7, and 13 are damaged.

FIG. 3 is a circuit diagram showing a configuration example of the semiconductor relays 6, 7, and 13.
In this semiconductor relay, the power supply voltage from the alternator 1 and the in-vehicle battery 4 is applied to each drain of an N-channel power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 18 and an N-channel MOSFET 19, and the source of the FET 18 (first switching element) is It is connected to a load (for example, electrical loads 8, 9, 10). An N-channel MOSFET 20 and a resistor R2 are connected in series between the source of the FET 19 (second switching element) and the ground terminal.

The output terminal of the operational amplifier 17 (current limiting circuit) is connected to the gate of the FET 20 (current limiting circuit), the non-inverting input terminal of the operational amplifier 17 is connected to the drain of the FET 20 (source of the FET 19), and the inverting input terminal is connected to the source of the FET 18. It is connected.
The gates of the FETs 18 and 19 are supplied with the same on / off signal from the power supply ECU 12 through the resistor R1 and the voltage across the resistor R2 is supplied to the power supply ECU12.

This semiconductor relay operates so that the operational amplifier 17 and the FET 20 have the same non-inverting input terminal voltage and inverting input terminal voltage of the operational amplifier 17.
The inverting input terminal voltage is obtained by dividing the power supply voltage by the ON resistance and the load resistance of the FET 18 and is a voltage corresponding to the load resistance. Further, since the current flowing through the FET 18 and the load resistance changes according to the change in the load resistance, the inverting input terminal voltage is a voltage according to the current flowing through the FET 18.

On the other hand, the non-inverting input terminal voltage is obtained by dividing the power supply voltage by the on-resistance of the FET 19, the on-resistance of the FET 20, and the resistor R2, and is a voltage corresponding to the on-resistance of the FET 20 and the current flowing through the resistor R2.
The operational amplifier 17 adjusts the current flowing through the resistor R2 by adjusting the on-resistance of the FET 20 so that the non-inverting input terminal voltage matches the inverting input terminal voltage. The power supply ECU 12 detects the current flowing through the FET 18 based on the voltage value at both ends.

FIG. 4 is a circuit diagram showing another configuration example of the semiconductor relays 6, 7, and 13.
In this semiconductor relay, the power supply voltage from the alternator 1 and the in-vehicle battery 4 is applied to the drain of the N-channel power MOSFET 18, and the source of the FET 18 is connected to a load (for example, electric loads 8, 9, 10). An ON / OFF signal is supplied from the power supply ECU 12 to the gate of the FET 18 through the resistor R 1, and a drain-source voltage Vds of the FET 18 is supplied to the power supply ECU 12.
In this semiconductor relay, the on-resistance between the drain and source of the FET 18 can be considered constant. Therefore, the power supply ECU 12 can detect the current flowing through the FET 18 based on the voltage Vds generated from the current flowing between the drain and source of the FET 18.

FIG. 5 is a circuit diagram showing another configuration example of the semiconductor relays 6, 7, and 13.
In this semiconductor relay, the power supply voltage from the alternator 1 and the in-vehicle battery 4 is applied to the drain of the N-channel power MOSFET 18, and the source of the FET 18 is applied to a load (for example, an electrical load 8, 9, 10) through a resistor (shunt resistor) R3. It is connected. An ON / OFF signal is supplied from the power supply ECU 12 to the gate of the FET 18 through the resistor R1, and a voltage across the resistor R3 is supplied to the power supply ECU 12.
In this semiconductor relay, since the resistor R3 is constant, the power supply ECU 12 can detect the current flowing through the FET 18 based on the voltage generated by the current flowing through the resistor R3.

  In the vehicular power supply apparatus having such a configuration, the switches 6S, 7S, 13S of the electric loads 8, 9, 10 are operated, the semiconductor relays 6, 7, 13 are turned on, the current starts to flow, and the electric load 8 , 9, 10, the current becomes an inrush current. At that time, when the current value becomes equal to or greater than a predetermined current value (current threshold), the semiconductor relays 6, 7, and 13 are turned off for a predetermined time.

Therefore, as shown in FIG. 6B, the current E flowing through the semiconductor relays 6, 7 and 13 is from 0 to a predetermined current value (current threshold) in a time corresponding to the time constant of the electric load circuit. After increasing, it returns to 0, and after a predetermined time, the operation of increasing from 0 to a predetermined current value is repeated again. As a result, as shown in FIG. 6 (a), the power supply voltage D is not momentarily greatly reduced, and the power supply voltage F (FIG. 6 (b)) is kept stable although there is some ups and downs. Can do.
The predetermined current value is determined based on the inrush current value of the electric load and the current value when the electric load is operating stably. However, if the predetermined current value is too close to the inrush current value, the effect of limiting the current is weakened. If the predetermined current value is too close to the current value at the time of stable operation of the electric load, the delay until the stable operation is reached increases.

By the way, when the electric load is a headlamp, for example, when the inrush current is not suppressed, changes in the gate voltage, output voltage, current, and lamp illuminance of the IPS (semiconductor relay) change as shown in FIG. Get up. The rise time when the illuminance is 0 to 80% is about 250 ms (milliseconds). FIG. 7B shows the current rising portion of FIG. 7A enlarged in terms of time, and the illuminance has not yet risen.
Since the rise of illuminance is related to the amount of current flowing in the filament, if the inrush current is suppressed, the rise of illuminance may be delayed.

Therefore, when the current value of the IPS (semiconductor relay) exceeds a predetermined current value, the time for turning off the IPS was changed, and the rise of the illuminance of the lamp in each case was measured.
FIG. 8A is a waveform diagram showing changes in the gate voltage, output voltage, current, and lamp illuminance of the IPS when the time for turning off the IPS is 70 μs (microseconds). In FIG. 8B, the upper half is the same as FIG. 8A, and the lower half shows the rising part of the current in the upper half in terms of time. Before getting up. Here, from FIG. 8A, when the time for turning off the IPS is 70 μs, the rise time of the lamp illuminance is about 360 ms, and the time for repeating the operation for turning off the IPS (current limit operation time), that is, The time until the resistance value of the filament increased and the current value became less than the predetermined current value was 140 ms.

  FIG. 9A is a waveform diagram showing changes in the gate voltage, output voltage, current, and lamp illuminance of the IPS when the time for turning off the IPS is 20 μs. In FIG. 9B, the upper half is the same as FIG. 9A, and the lower half shows the rising part of the current in the upper half in terms of time. Before getting up. Here, from FIG. 9A, when the time for turning off the IPS is 20 μs, the rise time of the illuminance of the lamp is about 320 ms, and the time for repeating the operation of turning off the IPS (current limit operation time) is 80 ms. Met.

  FIG. 10 shows the measurement results when the IPS turn-off time (return time after cut-off) is 40 μs, 10 μs, and 8 μs together with the measurement results of FIGS. It is a summary table. The time for turning off the IPS is about 70 μs to 40 μs, the delay in the rise of the lamp illuminance is about 0.1 second, the time for turning off the IPS is about 20 μs to 8 μs, and the delay in the rise of the lamp illuminance is 0. It is about 05 seconds. Therefore, by selecting the time for turning off the IPS, the delay in the rise does not become a problem, but it can be seen that the delay in the rise is eliminated as the time for turning off the IPS is shortened.

  By the way, the electric wire has a smoke generation characteristic determined by the current value and the flow time until the electric wire smokes, but conventionally, a fuse is used to prevent overcurrent, and the fuse blows. It has a fusing characteristic determined by the value of the current flowing until and the time of flowing. Therefore, before the fuse is blown out, the electric wire does not emit smoke, and allowance is made so that the current value of the fuming characteristic sufficiently exceeds the current value of the blowing characteristic as shown in FIG. Electric wire A was used, and electric wire A was thicker and heavier than necessary because of such smoke generation characteristics.

  However, when the current value of the semiconductor relay (IPS) becomes equal to or higher than the predetermined current value, the semiconductor relay is turned off for a predetermined time to eliminate the need for a fuse and to be used as shown in FIG. The smoke generation characteristic of the electric wire B can be brought close to the load use condition, and the electric wire B can be made thinner and lighter. Further, even when a fuse is used, the current does not flow above a predetermined current value, so that the smoke generation characteristic of the electric wire B can be brought closer to the load use condition than before by using a fuse whose current value of the fusing characteristic is smaller.

Hereinafter, the operation of controlling the semiconductor relay of such a vehicle power supply apparatus will be described with reference to the flowchart of FIG.
When the switch (for example, 6S, 7S, 13S) is operated to turn on the semiconductor relay (of the Nth semiconductor relay), the power supply ECU 12 of the vehicle power supply apparatus is configured to include the flag and parameters Fa, Fb, Ta, Tb. After this is initialized, this subroutine is executed. The subroutine is executed without initialization except when the semiconductor relay is turned on after being operated.
First, the power supply ECU 12 determines whether or not the flag Fa is 0 (S1). If the flag Fa is not 0 (Fa = 1), the process returns to the next routine. If the flag Fa is 0, it is determined whether or not the flag Fb is 0 (S3).

If the flag Fb is 0 (S3), the power supply ECU 12 reads the current value I of the semiconductor relay (S5), and the read current value I is equal to or greater than a predetermined current value (current threshold) I1 of the semiconductor relay. It is determined whether or not there is (S7). If the current value I is not greater than or equal to the predetermined current value I1, the process returns and proceeds to the next routine.
If the current value I is equal to or greater than the predetermined current value I1 (S7), the power supply ECU 12 turns off the semiconductor relay (S9), sets the flag Fb to 1 (S11), and adds 1 to the parameter Ta (S13). 1 is added to the parameter Tb (S15).
If the flag Fb is not 0 (S3), the power supply ECU 12 adds 1 to the parameter Tb (S15).

Next, the power supply ECU 12 determines whether or not the parameter Ta is greater than or equal to a predetermined value T1 (S17). If it is not equal to or greater than the predetermined value T1, it determines whether or not the parameter Tb is greater than or equal to the predetermined value T2 (S17). S19).
Here, the predetermined value T2 corresponds to a predetermined time during which the semiconductor relay is turned off when the current value of the semiconductor relay becomes equal to or higher than the predetermined current value. The predetermined value T1 corresponds to a time for detecting that the operation of turning off the semiconductor relay is repeated more than expected due to a short circuit on the electric load side or the like, and T1 >> T2.

The power supply ECU 12 returns if the parameter Tb is not equal to or greater than the predetermined value T2 (S19), and proceeds to the next routine. If the parameter Tb is equal to or greater than the predetermined value T2 (S19), the semiconductor relay is turned on (S21), the flag Fb is set to 0 (S23), the parameter Tb is set to 0 (S25), and the process returns to the next routine. .
If the parameter Ta is equal to or greater than the predetermined value T1 (S17), the power supply ECU 12 repeats the operation of turning off the semiconductor relay more than expected (for example, several hundred times) due to a short circuit on the electric load side or the like. While Fa is set to 1 (S27), the occurrence of abnormality is displayed and the process returns to the next routine.

In the above-described embodiment, when the current value of the semiconductor relay becomes equal to or higher than that value, the predetermined current value for turning off the semiconductor relay for a predetermined time is constant as shown in FIG. As shown in FIG. 14, the predetermined current value can be determined so as to change based on the elapsed time since the semiconductor relay is turned on.
In this case, for example, if the predetermined current value is set to change based on the waveform of the inrush current obtained by actual measurement, the delay until the electric load reaches the stable operation can be reduced.

It is a block diagram which shows schematic structure of embodiment of the vehicle power supply device which concerns on this invention. It is a block diagram which shows the other schematic structure of embodiment of the vehicle power supply device which concerns on this invention. It is a circuit diagram which shows the structural example of a semiconductor relay. It is a circuit diagram which shows the other structural example of a semiconductor relay. It is a circuit diagram which shows the other structural example of a semiconductor relay. It is explanatory drawing which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a wave form diagram which shows the example of operation | movement of the conventional vehicle power supply device. It is a wave form diagram which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a wave form diagram which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a table | surface which shows the actual measurement result when changing time to turn off IPS. It is a characteristic view for demonstrating the example of an effect | action and effect of the vehicle power supply device which concerns on this invention. It is a flowchart which shows the operation | movement which controls the semiconductor relay of the vehicle power supply device which concerns on this invention. It is a wave form diagram which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a wave form diagram which shows the example of operation | movement of the vehicle power supply device which concerns on this invention.

Explanation of symbols

1 Alternator (on-vehicle generator, AC generator)
4 On-board battery 6, 7, 13 Semiconductor relay (switch circuit)
6s, 7s, 13s switch 8, 9, 10 Electric load 11 Relay box 12 Power supply ECU (detection means, determination means, off means)
14 memory 15 engine 17 operational amplifier (current limiting circuit)
18 N-channel power MOSFET (first switching element)
19 N-channel MOSFET (second switching element)
20 N-channel MOSFET (current limiting circuit)
F1, F2, F3 fuses R1, R2, R3 resistors

Claims (4)

An in-vehicle battery charged with electric power generated by an in-vehicle generator in conjunction with an engine, electric power discharged from the in-vehicle battery, and a plurality of switches for supplying electric power generated by the in-vehicle generator to a plurality of loads, respectively In a vehicle power supply device comprising a circuit,
Detection means for detecting a current value flowing through the switch circuit when the switch circuit is on; a determination means for determining whether the current value detected by the detection means is equal to or greater than a predetermined current value; An off means for turning off the switch circuit for a predetermined time when the determination means determines that the current value is equal to or greater than a predetermined current value ;
The switch circuit is a semiconductor relay having a current detection function, and the determination unit is configured to determine whether or not a current value detected by the current detection function is equal to or greater than a predetermined current value.
The semiconductor relay includes a first switching element that turns on / off a current flowing through a load, a second switching element that turns on / off in the same manner as the first switching element, and a current that flows through the second switching element. A current limiting circuit that limits current according to a current flowing through the element, and a series circuit having a resistance through which the current that is limited by the current limiting circuit flows, wherein the first switching element and the series circuit are connected in parallel, based on the voltage across the resistor, the vehicle power supply device according to claim configured tare Rukoto to detect a current flowing through the first switching element. When said off means is performed iteratively a predetermined number of times or for a predetermined time the operation of the switching circuit at a predetermined time off, claim 1 Symbol placement vehicle power is arranged to turn off the switch circuit apparatus. 3. The vehicle power supply device according to claim 1, wherein the predetermined current value for each of the switch circuits is determined so as to change based on an elapsed time since the switch circuit is turned on. Wires for connecting between the switch circuit and load, fuming characteristics wire is determined by the current value and flowing time flowing in until fuming, any one of claims 1 to 3 is not less than the predetermined current value of the switching circuit 1 The vehicle power supply device according to Item.

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