JP2019006337A - On-vehicle electric system - Google Patents

Abstract

To enable charging of a first battery by a power generator with a motor function, make both the first battery and a second battery available as a power source for the power generator with the motor function, and further prevent breakage of a relay while enabling voltage guarantee of a first load connected to the first battery.SOLUTION: An on-vehicle electric system according to the present invention comprises: a relay; first and second batteries connected in parallel via the relay; a first load connected in parallel to the first battery without interposing the relay; a power generator with a motor function connected in parallel to the second battery without interposing the relay; and a control part that performs relay-off control of changing the relay to an off state in response to a condition that the current value of a current flowing to the relay becomes equal to or more than a threshold value, and performs control of reducing the current value within a time required for off, which is from start of the relay-off control to turning-off of the relay.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a relay, a first battery and a second battery connected in parallel via the relay, a first load connected in parallel to the first battery without passing through the relay, and a second battery without going through the relay. And in-vehicle electric system including a generator with a motor function connected in parallel.

  For example, some vehicles such as automobiles include a generator with motor function (ISG: Integrated Starter Generator) as a generator for charging an auxiliary battery for driving auxiliary machines. In addition to the power generation function that converts engine torque into electric power, the ISG can convert electric power into engine torque and use it to start the engine. Therefore, the functions of both the starter motor for starting the engine and the alternator that generates power using the engine torque can be integrated into the ISG.

  In a vehicle equipped with an ISG, the IGS can be used not only for engine start but also for engine torque assist during traveling. However, in such a case, if the power source of the ISG is only the auxiliary battery, the carry-out of electric power from the auxiliary battery accompanying torque assist becomes large, and it is difficult to guarantee the voltage of the auxiliary machines. Here, the voltage guarantee means that the input voltage of the auxiliary equipment is not lower than the minimum operation guarantee voltage determined for the auxiliary equipment.

Therefore, a traveling battery is provided as a torque assist power source separately from the auxiliary battery, and the auxiliary battery and the traveling battery are connected in parallel via a relay, resulting in high loads such as during torque assist. In the situation, it is effective to have a configuration in which the traveling battery and the auxiliary battery are disconnected by turning off the relay.
For example, in Patent Document 1 below, an electric motor that is mechanically connected to a drive shaft of an internal combustion engine and operates to assist torque of the internal combustion engine, a first battery that supplies electric power to the electric motor during torque assist execution, A second battery that supplies electric power to an electric load other than the motor during execution of torque assist, and a relay that connects the first battery and the second battery in parallel when torque assist is not executed and releases the parallel connection when torque assist is executed. A torque assist control device is disclosed.

JP 2013-256267 A

However, if the relay is turned off when the load is high, such as during torque assist, the relay may be turned off while a large current is flowing.
If the relay is turned off while a large current is flowing, the relay may be welded and damaged.

  Therefore, the present invention overcomes the above-mentioned problems, enables charging of the first battery by the generator with motor function, enables both the first battery and the second battery to be used as the power source of the generator with motor function, It is another object of the present invention to prevent damage to the relay while ensuring the voltage of the first load connected to the first battery.

  An in-vehicle electrical system according to the present invention includes a relay, a first battery and a second battery connected in parallel via the relay, a first load connected in parallel to the first battery without passing through the relay, A generator with a motor function that is connected in parallel with the second battery without passing through the relay, and a relay-off control that switches the relay to an off state in response to the current value of the current flowing through the relay being equal to or greater than a threshold value. And a control unit that performs control to reduce the current value within a time required to turn off the relay until the relay is turned off.

  The connection form of the relay, the first battery, the first load, the second battery, and the motor function generator allows the first battery to be charged by the motor function generator. Both can be used as the power source of the generator with a motor function, and the voltage of the first load connected to the first battery can be guaranteed by turning off the relay. Further, the above-described control unit can prevent the relay from being turned off in a state where a large current is flowing.

  The above-described in-vehicle electric system according to the present invention includes a second load connected in parallel with the second battery without the relay, and the control unit is larger than the case where the power consumption of the second load is small. In this case, it is possible to increase the threshold and control the power consumption of the second load to be lowered when the relay-off control is started.

  As a result, it is possible to set a high threshold according to the power consumption state of the second load, and when the power consumption of the second load is large, the current value of the relay current is lowered at the start of the relay-off control. It is possible to prevent the relay from being turned off in a state where the current is flowing.

  In the above-described in-vehicle electric system according to the present invention, the second load may be a vehicle room temperature control device.

  Since the vehicle room temperature control device has a relatively large power consumption, when the power consumption is lowered, the vehicle temperature control device contributes relatively greatly to the reduction in the current value of the relay current.

  In the above-described in-vehicle electric system according to the present invention, the control unit increases the threshold value when the power consumption of the first load is smaller than when it is large, and the relay off control is started when the relay off control is started. It is possible to adopt a configuration that performs control to increase the power consumption of one load.

  As a result, the same effect as when the power consumption on the second load side is reduced can be obtained.

  In the above-described in-vehicle electric system according to the present invention, when the upper limit value of the current allowed to flow through the relay is the maximum guaranteed current value, the minimum value of the threshold value is the motor within the time required for off. When the required driving force of the function generator maintains the maximum slope, the current value can be set to a value that does not exceed the maximum guaranteed current value.

  Thereby, for example, when the device as the second load is in the off state, or the device as the first load is in the maximum power consumption state, the current value after the relay off control is started can be reduced by adjusting the power consumption of those loads. Even in an impossible situation, the current value of the relay current can be prevented from exceeding the maximum guaranteed current value.

  The above-described in-vehicle electric system according to the present invention can be configured to include a diode that is connected in parallel to the relay and flows current from the second battery side to the first battery side.

  Thereby, even if the relay is OFF, it is possible to allow current to flow only from the motor function generator side to the first battery side via the diode.

  Another on-vehicle electric system according to the present invention includes a relay, a first battery and a second battery connected in parallel via the relay, and a first battery connected in parallel to the first battery without passing through the relay. One load, a generator with a motor function connected in parallel with the second battery without passing through the relay, and information indicating the required driving force of the generator with a motor function is acquired, and the magnitude of the required driving force And a controller that performs relay-off control for switching the relay to an OFF state based on the above.

  Even in the above-described other in-vehicle electrical system, when the relay is turned on, the first battery can be charged by the motor function generator, and both the first battery and the second battery are connected to the motor function generator. It can be used as a power source, and the voltage of the first load connected to the first battery can be guaranteed by turning off the relay. Then, the control unit can turn off the relay in advance in response to a case where the current value of the relay current is predicted to increase.

  According to the present invention, the first battery can be charged by the generator with motor function, and both the first battery and the second battery can be used as the power source of the generator with motor function, and further connected to the first battery. In addition, it is possible to prevent damage to the relay while ensuring the voltage of the first load.

It is a circuit block diagram showing an example of composition of an in-vehicle electric system as a first embodiment concerning the present invention. It is explanatory drawing of the effect | action by power consumption adjustment and threshold value adjustment as 1st embodiment. It is the flowchart which showed the procedure of the process which should be performed in order to implement | achieve the relay-off control method of 1st embodiment. It is the circuit block diagram which showed the structural example of the vehicle-mounted electrical system as 2nd embodiment. It is the circuit block diagram which showed the structural example of the vehicle-mounted electrical system as 3rd embodiment. It is the flowchart which showed the procedure of the process which should be performed in order to implement | achieve the relay-off control method as 3rd embodiment.

<1. First embodiment>
FIG. 1 is a circuit block diagram showing a configuration example of an in-vehicle electric system 1 as a first embodiment according to the present invention.
The in-vehicle electric system 1 according to the present embodiment is provided in a vehicle including an engine as a driving source for wheels. In this example, the vehicle is a vehicle having an idling stop function that stops the engine without depending on the engine stop operation when a predetermined condition including a vehicle speed condition is satisfied.

As shown in the figure, an in-vehicle electrical system 1 includes, for example, an auxiliary device 2 as various electric devices mounted on the vehicle, a first battery Bth used as a power source for the auxiliary device 2, and an ISG (Integrated) as a generator with a motor function. Starter Generator) 3, a second battery Bti used as a power source for ISG 3, a relay RL as an electromagnetic relay, and a specific load 4 as a specific electric load connected in parallel to ISG 3.
As illustrated, the first battery Bth and the second battery Bti are connected in parallel via a relay RL. The auxiliary machinery 2 is connected in parallel with the first battery Bth without going through the relay RL, and the specific load 4 is connected in parallel with the second battery Bti without going through the relay RL.
As the first battery Bth and the second battery Bti, for example, a nickel metal hydride battery or a lithium ion battery can be used. In this example, the rated output voltage is about 12V, for example.
A lead storage battery can be used for at least one of the first battery Bth and the second battery Bti.
In this example, the specific load 4 is a vehicle room temperature adjustment device that adjusts the temperature of the passenger compartment.

  In the in-vehicle electric system 1, the first battery Bth can be charged by the ISG 3 with the above-described electric circuit configuration (when the relay RL is on). Further, both the first battery Bth and the second battery Bti can be used as the power source of the ISG 3 (when the relay RL is on). Further, it is possible to guarantee the voltage of the auxiliary machinery 2 connected to the first battery Bth (when the relay RL is off).

  The in-vehicle electric system 1 includes a diode D1 connected in parallel to the relay RL. As illustrated, the diode D1 has an anode connected to the positive terminal of the second battery Bti and a cathode connected to the positive terminal of the first battery Bth. That is, the diode D1 allows a current to flow from the second battery Bti side to the first battery Bth side.

The ISG 3 is connected to the rotating shaft of the engine and serves as a starter motor that starts the engine by functioning as a motor (electric motor). Further, the ISG 3 can function as a generator that recovers the rotational energy of the engine as electric energy after the engine is started.
Further, the ISG 3 can perform engine torque assist by functioning as a motor.

The in-vehicle electrical system 1 includes a travel control unit 5 configured with a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 6, the relay control unit 7, the ISG drive unit 8 that drives the ISG 3 based on an instruction from the travel control unit 5, and the above-described control units (the travel control unit 5, the load control unit 6, the relay control unit 7 ) Are connected to each other so that mutual data communication is possible.
The mutual data communication of the travel control unit 5, the load control unit 6, and the relay control unit 7 is performed in a format according to a predetermined in-vehicle LAN (Local Area Network) standard such as CAN (Controller Area Network).

The traveling control unit 5 performs control related to traveling of the vehicle, and particularly in this example, performs control for realizing the idling stop function described above and control for engine torque assist by the ISG 3.
Specifically, the traveling control unit 5 causes the ISG driving unit 8 to function the ISG 3 as a starter motor when the engine is restarted due to the idling stop function. In addition, as a process related to torque assist, the traveling control unit 5 calculates a required driving force of the ISG 3 based on an accelerator pedal operation or the like (not shown) so that the ISG 3 expresses a driving force corresponding to the required driving force. Then, the ISG drive unit 8 is caused to output a drive signal corresponding to the required drive force.

The load control unit 6 controls the electrical equipment provided as the specific load 4.
In this example, the vehicle room temperature control device as the specific load 4 is controlled based on, for example, operation input or a detection signal of a sensor (not shown) (for example, an outside air temperature sensor or an inside air temperature sensor that detects the vehicle interior temperature).

The relay control unit 7 performs control related to ON / OFF of the relay RL.
Specifically, the relay control unit 7 of the present embodiment has various functions shown as a current detection unit 7a, an off control unit 7b, a threshold adjustment unit 7c, and a power adjustment instruction unit 7d in the drawing.
The current detector 7a detects the current value of the current flowing through the relay RL. Hereinafter, the current flowing through the relay RL may be referred to as “relay current Ir”.
The current detection unit 7a in this example detects a potential difference between a connection point potential between the relay RL and the first battery Bth and a connection point potential between the relay RL and the second battery Bti as a current value of the relay current Ir.
Note that the current detection unit 7a can be configured by an A / D converter that digitally samples both potentials and a difference detection circuit (that is, configured by hardware). Alternatively, the difference value calculation of both potentials may be realized by software processing.

  The off control unit 7b performs control to turn off the relay RL (relay off control) based on the current value of the relay current Ir detected by the current detection unit 7a and the threshold value THr when the relay RL is on. Specifically, relay-off control is performed in response to the current value of the relay current Ir becoming equal to or greater than the threshold value THr.

The threshold adjustment unit 7c adjusts the threshold THr used by the off control unit 7b in accordance with the power consumption of the specific load 4. Specifically, information correlating with the power consumption of the specific load 4 (hereinafter “power consumption correlation information”) is acquired from the load control unit 6 and the threshold value THr is adjusted based on the power consumption correlation information.
Here, as the power consumption correlation information, when the load control unit 6 calculates the power consumption of the specific load 4, information representing the power consumption may be used. Alternatively, in particular, when the specific load 4 is a vehicle room temperature controller as in this example, information indicating the magnitude of the output air volume can be used as power consumption correlation information. The power consumption correlation information may be information correlated with the magnitude of power consumption, and is not limited to information representing power consumption itself.

  Specifically, the threshold adjustment unit 7c adjusts the threshold THr to be larger when the power consumption of the specific load 4 is larger than when the power consumption of the specific load 4 is smaller as the adjustment of the threshold THr based on the power consumption correlation information.

  The power adjustment instruction unit 7d instructs the load control unit 6 to reduce the power consumption of the specific load 4 when the off control unit 7b starts the relay off control.

Here, the adjustment of the power consumption of the specific load 4 and the adjustment of the threshold value THr as described above are performed in order to extend the life of the relay RL by reducing the OFF frequency of the relay RL.
If the relay RL is turned off in a high load situation such as during engine torque assist using the ISG 3, the relay RL is turned off while a large current is flowing, and the relay RL may be welded and damaged. Considering this point, it is conceivable that the threshold THr used when the relay RL is turned off is set to a low value with a sufficient margin.
However, when the threshold value THr is set to a low value, the relay RL is frequently turned off, and the life of the relay RL may be reduced.

With reference to FIG. 2, the point that the life of the relay RL can be extended by adjusting the power consumption of the specific load 4 and adjusting the threshold value THr will be described.
First, with reference to FIG. 2A, how to determine the minimum value of the threshold value THr will be described. The minimum value of the threshold THr can be rephrased as the minimum value of the threshold THr that can be adjusted by the threshold adjuster 7c.

In FIG. 2A, “required drive force” in the figure illustrates the waveform of the required drive force of ISG 3 calculated by the travel control unit 5, and “specific load output” indicates the output state (power consumption) of the specific load 4. State). Here, the case where the gradient α of the required driving force is maximized is illustrated. That is, for example, when the accelerator pedal is suddenly depressed, the required driving force is raised at the fastest speed in the system.
In FIG. 2A, the vehicle room temperature control device as the specific load 4 is turned off, and the power consumption is substantially zero (substantially no power consumption state).

  The relay current Ir in FIG. 2A exemplifies a waveform corresponding to the case where the inclination α of the required driving force is maximized. The inclination angle of the waveform of the relay current Ir at this time becomes the maximum angle when the specific load 4 is substantially in the power non-consumption state (that is, when the threshold adjustment unit 7c adjusts the threshold value THr to the minimum value) (however, And assuming that there is no voltage fluctuation on the first battery Bth side).

  A maximum guaranteed current value Lmi represented by a broken line in the drawing represents an upper limit value of a current allowed to flow through the relay RL in order to prevent welding of the relay RL. That is, if the current value of the relay current Ir is equal to or less than the maximum guaranteed current value Lmi, it is guaranteed that no welding occurs in the relay RL even if the relay RL is turned off.

  As described above, the off control unit 7b performs the relay off control in response to the current value of the relay current Ir becoming equal to or greater than the threshold value THr. However, the relay RL is actually switched to the off state after the relay off control is started. It takes some time to complete. In the figure, the time required from the start of the relay-off control until the relay RL actually switches to the OFF state is indicated as “OFF required time”.

In this example, the minimum value of the threshold value THr is set as follows.
That is, the minimum value of the threshold THr is set as a value at which the current value of the relay current Ir does not exceed the maximum guaranteed current value Lmi even when the required driving force of the ISG 3 maintains the maximum inclination within the required time for turning off. ing.
Thereby, even when the specific load 4 is in the OFF state and the current value of the relay current Ir cannot be reduced due to the power consumption limitation of the specific load 4 described in detail below, the relay current Ir It can be guaranteed that the relay RL shifts to the off state before the current value exceeds the maximum guaranteed current value Lmi. That is, the relay RL is prevented from being turned off in a state where a large current exceeding the maximum guaranteed current value Lmi flows even in a situation where the relay current Ir cannot be reduced due to the power consumption limitation of the specific load 4. Can do.

FIG. 2B is an explanatory diagram of the effect of adjusting the power consumption of the specific load 4 and adjusting the threshold value THr according to the power consumption of the specific load 4.
When the power consumption of the specific load 4 is large, the threshold value adjustment unit 7c adjusts the threshold value THr to a value larger than the minimum value shown in FIG. 2A. FIG. 2B shows an example in which the power consumption of the specific load 4 is considerably large and the threshold value THr is adjusted to a value exceeding the maximum guaranteed current value Lmi.

  The power adjustment instruction unit 7d performs control to reduce the power consumption of the specific load 4 when the current value of the relay current Ir becomes equal to or greater than the threshold value THr and the off control unit 7b starts the relay off control. By performing this control, the current value of the relay current Ir decreases after the start of the relay-off control as shown in the figure. Then, the current value of the relay current Ir is reduced in this way, so that the end time of the required turn-off time can be reached in a state where the current value of the relay current Ir is equal to or less than the maximum guaranteed current value Lmi. That is, the relay RL can be shifted to an off state in a state where the current value of the relay current Ir is equal to or less than the maximum guaranteed current value Lmi, thereby preventing the relay RL from being damaged.

Here, in the present embodiment, the threshold THr is adjusted from the minimum value shown in FIG. 2A to a large value that exceeds the maximum guaranteed current value Lmi as shown in FIG. 2B by the threshold adjustment unit 7c. In the drawing, such an adjustment range of the threshold THr is represented by “X”.
In the present embodiment, the threshold value THr can be set to a value larger than the minimum value shown in FIG. 2A by reducing the relay current Ir by adjusting the power consumption of the specific load 4 as shown in FIG. 2B. Since the threshold THr can be increased in this way, the frequency with which the relay RL is turned off can be reduced, and thereby the life of the relay RL can be extended.

FIG. 3 is a flowchart showing processing to be executed by the relay control unit 7 in order to realize the functions as the off control unit 7b, the threshold adjustment unit 7c, and the power adjustment instruction unit 7d.
Note that each process shown in FIG. 3 is executed by the CPU of the relay control unit 7 according to a program stored in a predetermined storage device such as the ROM described above.

FIG. 3A shows a process for realizing the function as the off control unit 7b. In addition, the relay control part 7 repeatedly performs the process of FIG. 3A and FIG. 3B mentioned later by a predetermined | prescribed process cycle.
In FIG. 3A, the relay control unit 7 acquires the current value of the relay current Ir detected by the current detection unit 7a as the current value acquisition processing in step S101, and whether or not the acquired current value is equal to or greater than the threshold value THr in step S102. Determine.
If the current value is not equal to or greater than the threshold value THr, the relay controller 7 finishes the process shown in FIG. 3A. If the current value is equal to or greater than the threshold value THr, the relay control is performed in step S103, and the process shown in FIG.

FIG. 3B shows a process for realizing the function as the threshold adjustment unit 7c.
In step S201, the relay control unit 7 performs processing for acquiring power consumption correlation information from the load control unit 6, and in step S202 performs processing for updating to a threshold value THr corresponding to power consumption. That is, a value corresponding to the magnitude of power consumption of the specific load 4 obtained from the power consumption correlation information is obtained as a candidate value for the threshold THr, and the current threshold THr is updated with the candidate value. At this time, the relay control unit 7 obtains the candidate value based on, for example, a function or table information indicating a correspondence relationship between the power consumption of the specific load 4 and the threshold value THr. In the present embodiment, these functions and tables are set so that a large candidate value can be obtained when the power consumption of the specific load 4 is larger than when it is small. That is, the threshold value THr is updated to a large value when the power consumption is larger than when the power consumption is small.
The relay control unit 7 ends the process shown in FIG. 3B in response to performing the update process in step S202.

FIG. 3C shows a process for realizing the function as the power adjustment instruction unit 7d.
In FIG. 3C, the relay control unit 7 waits until the relay-off control is started in step S301, and when the relay-off control is started, starts the time count in step S302 and then performs the power adjustment instruction process in step S303. Do. That is, it instructs the load control unit 6 to reduce the power consumption of the specific load 4.

  In response to such a power adjustment instruction, if the vehicle room temperature control device as the specific load 4 is in the on state, the load control unit 6 reduces the power consumption of the specific load 4 by a predetermined control such as, for example, reducing the output air volume. Reduce. The control for reducing the power consumption of the specific load 4 may include a control for turning off the specific load 4 (making the power consumption zero).

In response to the execution of the instruction process in step S303, the relay control unit 7 waits for a predetermined time to elapse in step S304, and in response to the elapse of the predetermined time, the time count is reset in step S305, and then in step S306. The release instruction process is performed with. That is, an instruction for canceling the power consumption adjustment state of the specific load 4 (the power consumption restriction state in this embodiment) is issued to the load control unit 6.
Thereby, the operation state of the specific load 4 can be returned to the state before the adjustment instruction is executed in step S303.

  The relay control unit 7 ends the process shown in FIG. 3C in response to the execution of the instruction process in step S306.

<2. Second embodiment>
FIG. 4 is a circuit block diagram showing a configuration example of the in-vehicle electrical system 1A as the second embodiment.
In the following description, parts that are the same as the parts that have already been described are assigned the same reference numerals and description thereof is omitted.

The action of reducing the current value of the relay current Ir can also be realized by increasing the power consumption of the auxiliary machinery 2.
In the in-vehicle electrical system 1A of the second embodiment, an auxiliary machinery control unit 10 that controls the auxiliary machinery 2 is provided, and the relay control unit 7 supplies the auxiliary machinery control unit 10 with the power consumption of the auxiliary machinery 2. Instruct to raise. In this example, the auxiliary equipment control unit 10 includes a microcomputer having a ROM, a RAM, and a CPU, and can perform data communication with at least the relay control unit 7 via the bus 9. It is said that.

The relay control unit 7 included in the in-vehicle electrical system 1A includes a threshold adjustment unit 7cA instead of the threshold adjustment unit 7c, and a power adjustment instruction unit 7dA instead of the power adjustment instruction unit 7d.
Based on the power consumption correlation information acquired from the auxiliary machinery control unit 10, the threshold adjustment unit 7cA adjusts the threshold THr so as to increase the threshold THr when the power consumption of the auxiliary machinery 2 is smaller than when the power consumption is large. I do.
In addition, the power adjustment instruction unit 7dA instructs the auxiliary equipment control unit 10 to increase the power consumption of the auxiliary equipment 2 when the off control section 7b starts the relay-off control.

In this case, the relay control unit 7 performs processing similar to that shown in FIGS. 3B and 3C as processing for realizing the functions of the threshold adjustment unit 7cA and the power adjustment instruction unit 7b. However, in this case, what is acquired in step S201 in FIG. 3B is the power consumption correlation information for the auxiliary machinery 2. In the process of step S202, the power consumption of the auxiliary machinery 2 is large as the above-described threshold THr candidate value. When the value is smaller than the case, a large value is obtained.
In the process of FIG. 3C, the instruction target in steps S303 and S306 is the auxiliary machinery control unit 10, and in the process of step S303, an instruction to increase the power consumption of the auxiliary machinery 2 is issued.

  Also in the in-vehicle electrical system 1A of the second embodiment as described above, similarly to the in-vehicle electrical system 1, the control for reducing the current value of the relay current Ir is realized within the time required to turn off the relay RL. Then, the frequency of turning off the relay RL is reduced as in the first embodiment by adjusting the current value within the required turn-off time and adjusting the threshold value THr according to the power consumption of the accessories 2. However, it is possible to prevent the relay RL from being turned off when a large current is flowing.

  In the above description, the auxiliary machine 2 is controlled by the auxiliary machine control unit 10. However, depending on the type of the auxiliary machine 2, the auxiliary machine 2 may include a computer. In this case, the power adjustment instruction unit 7dA can also be configured to issue a power adjustment instruction to the computer.

  Here, in the second embodiment, as an example of the auxiliary machines 2 to be adjusted in power consumption, for example, an EOP (Electric Oil Pump) used as a radiator fan of an engine or a hydraulic oil discharge source of a transmission, etc. Can be mentioned.

In addition, the relay current Ir can be reduced by both the power consumption adjustment of the auxiliary machinery 2 and the power consumption adjustment of the specific load 4 described in the first embodiment. That is, the control for reducing the power consumption of the specific load 4 and increasing the power consumption of the auxiliary machinery 2 is performed in response to the start of the OFF control of the relay RL.
In this case, the threshold value THr is larger when the power consumption of the specific load 4 is large and the power consumption of the auxiliary machinery 2 is smaller than when the power consumption of the auxiliary machinery 2 is large. You just have to adjust it.

<3. Third Embodiment>
FIG. 5 is a circuit block diagram showing a configuration example of the in-vehicle electrical system 1B as the third embodiment.
The difference from the in-vehicle electrical system 1 of the first embodiment is that a relay control unit 7B is provided instead of the relay control unit 7.
The relay control unit 7B is different from the relay control unit 7 in that the current detection unit 7a, the threshold adjustment unit 7c, and the power adjustment instruction unit 7d are omitted, and an off control unit 7bB is provided instead of the off control unit 7b. Different.

Here, when the required driving force of the ISG 3 calculated by the traveling control unit 5 increases, the increase in the required driving force is reflected in the driving signal of the ISG 3 after the annealing time at a predetermined rate. In other words, a required time lag occurs between the increase in the required driving force and the increase in the current value of the relay current Ir. Therefore, by detecting an increase in the required driving force, it is possible to prefetch the increase in the current value of the relay current Ir.
In view of this point, in the third embodiment, the off control unit 7bB performs relay off control based on the magnitude of the required driving force of the ISG3.

FIG. 6 is a flowchart showing processing for realizing the relay-off control method as the third embodiment.
The processing shown in FIG. 6 is executed by the CPU in the relay control unit 7B in accordance with a program stored in a predetermined storage device such as a ROM, and is repeatedly performed at a predetermined processing cycle.

  In FIG. 6, the relay control unit 7 </ b> B performs a process for acquiring the required driving force of the ISG 3 in step S <b> 401. That is, a request for transmission of the required driving force of ISG 3 is made to the traveling control unit 5 to acquire the required driving force.

  In subsequent step S402, the relay control unit 7B determines whether or not the acquired requested driving force is equal to or greater than a predetermined threshold value THd. If the requested driving force is not equal to or greater than the threshold value THd, the process illustrated in FIG. If the required driving force is greater than or equal to the threshold value THd, relay off control is performed in step S403, and the process shown in FIG.

According to the above processing, the relay RL is turned off in advance in response to a case where it is predicted that the current value of the relay current Ir will increase to, for example, the maximum guaranteed current value Lmi from the magnitude of the required driving force. It is possible.
Therefore, it is possible to prevent the relay RL from being turned off while a large current is flowing.

<4. Summary of Embodiment>
As described above, the in-vehicle electrical system (1 or 1A) of the embodiment includes a relay (RL), a first battery (Bth) and a second battery (Bti) connected in parallel via the relay, and a relay. The first load (auxiliary device 2) connected in parallel with the first battery without using the relay, the generator with motor function (ISG3) connected in parallel with the second battery without using the relay, and the current flowing through the relay Control to perform relay-off control that switches the relay to the OFF state in response to the current value of the current having exceeded the threshold value, and control to decrease the current value within the required OFF time from the start of the relay-OFF control until the relay is turned OFF (Relay control unit 7 or 7A).

When the relay is turned on, the first battery can be charged by the motor function generator when the relay, the first battery, the first load, the second battery, and the motor function generator are connected. In addition, both the first battery and the second battery can be used as the power source of the generator with a motor function. Furthermore, the voltage of the first load connected to the first battery can be guaranteed by turning off the relay. The control unit can prevent the relay from being turned off while a large current is flowing.
Therefore, according to the on-vehicle electric system described above, the first battery can be charged by the generator with motor function, and both the first battery and the second battery can be used as the power source of the generator with motor function. It is possible to prevent damage to the relay while ensuring the voltage of the first load connected to one battery.

  Moreover, in-vehicle electric system (1) of embodiment is equipped with the 2nd load (specific load 4) connected in parallel with the 2nd battery without passing through a relay, and a control part has small power consumption of 2nd load. When the value is larger than the case, the threshold value is increased, and the control to reduce the power consumption of the second load is performed when the relay-off control is started.

As a result, it is possible to set a high threshold according to the power consumption state of the second load, and when the power consumption of the second load is large, the current value of the relay current is lowered at the start of the relay-off control. It is possible to prevent the relay from being turned off in a state where the current is flowing.
Since it is possible to set a high threshold as a threshold for turning off the relay, it is possible to reduce the on / off frequency of the relay. Therefore, according to the above configuration, it is possible to prevent the relay from being damaged when the relay is turned off in a state where a large current flows while extending the life of the relay.

  Furthermore, in the vehicle-mounted electric system of the embodiment, the second load is a vehicle room temperature adjustment device.

Since the vehicle room temperature control device consumes a relatively large amount of power, when the power consumption is lowered, it contributes relatively greatly to the reduction in the current value of the relay current.
Accordingly, the upper limit value of the threshold value can be increased, and the relay OFF frequency can be reduced, that is, the life of the relay can be extended.

  Furthermore, in the in-vehicle electrical system (1A) of the embodiment, the control unit increases the threshold when the power consumption of the first load is smaller than when it is large, and the first load is triggered by starting relay-off control. Control to increase the power consumption.

As a result, the same effect as when the power consumption on the second load side is reduced can be obtained.
Therefore, it is possible to extend the life of the relay by reducing the frequency with which the relay is turned off, and to prevent the relay from being damaged when the relay is turned off while a large current is flowing.

  In the in-vehicle electrical system of the embodiment, when the upper limit value of the current allowed to flow through the relay is the maximum guaranteed current value, the minimum value of the threshold is the value of the generator with motor function within the time required for off. When the required driving force maintains the maximum inclination, the current value is set to a value that does not exceed the maximum guaranteed current value.

Thereby, for example, when the device as the second load is in the off state, or the device as the first load is in the maximum power consumption state, the current value after the relay off control is started can be reduced by adjusting the power consumption of those loads. Even in an impossible situation, the current value of the relay current can be prevented from exceeding the maximum guaranteed current value.
Therefore, even if it is impossible to reduce the current value after the start of relay-off control by adjusting the power consumption of the load, the relay can be prevented from being damaged when the relay is turned off while a large current is flowing. Can do.

  Furthermore, the in-vehicle electrical system of the embodiment includes a diode that is connected in parallel to the relay and flows current from the second battery side to the first battery side.

Thereby, even if the relay is OFF, it is possible to allow current to flow only from the motor function generator side to the first battery side via the diode.
Therefore, even when the relay is off, the regenerative power by the generator with motor function and the charging power of the second battery can be supplied to the first battery side, the non-charging time of the first battery can be shortened, and the first load The voltage guarantee effect can be enhanced.

  Further, another on-vehicle electric system (1B) of the embodiment includes a relay (RL), a first battery (Bth) and a second battery (Bti) that are connected in parallel via the relay, and the first battery without the relay. The first load (auxiliary machine 2) connected in parallel with one battery, the generator with motor function (ISG3) connected in parallel with the second battery without a relay, and the required driving force of the generator with motor function And a control unit (relay control unit 7B) that performs relay-off control for switching the relay to an OFF state based on the magnitude of the required driving force.

Even in the above-described other in-vehicle electrical system, when the relay is turned on, the first battery can be charged by the motor function generator, and both the first battery and the second battery are connected to the motor function generator. It can be used as a power source, and the voltage of the first load connected to the first battery can be guaranteed by turning off the relay. Then, the control unit can turn off the relay in advance in response to a case where the current value of the relay current is predicted to increase.
Therefore, even with the other in-vehicle electric system, the first battery can be charged by the generator with motor function, and both the first battery and the second battery can be used as the power source of the generator with motor function. It is possible to prevent damage to the relay while ensuring the voltage of the first load connected to one battery.

The present invention is not limited to the specific examples described above, and various modifications can be considered.
For example, in the above description, the present invention is applied to a vehicle having an idling stop function. However, the present invention can also be suitably applied to a vehicle having no idling stop function.

  1, 1A, 1B In-vehicle electrical system, 2 Auxiliaries (first load), 3 ISG (generator with motor function), Bth 1st battery, Bti 2nd battery, RL relay, 4 Specific load (2nd load) , 6 Load control unit, 7, 7B, relay control unit, 7a current detection unit, 7b, 7bB off control unit, 7c, 7cA threshold adjustment unit, 7d, 7dA power adjustment instruction unit, 10 accessory control unit, D1 diode

Claims (7)

Relay,
A first battery and a second battery connected in parallel via the relay;
A first load connected in parallel with the first battery without the relay;
A generator with a motor function connected in parallel with the second battery without going through the relay;
Performing relay off control for switching the relay to an off state in response to the current value of the current flowing through the relay being equal to or greater than a threshold value, and within the required time from the start of the relay off control until the relay is turned off A vehicle-mounted electrical system comprising: a control unit that performs control to reduce the current value. A second load connected in parallel with the second battery without the relay,
The controller is
Increasing the threshold if the power consumption of the second load is greater than if it is small;
The in-vehicle electric system according to claim 1, wherein control for reducing power consumption of the second load is performed when the relay-off control is started. The in-vehicle electric system according to claim 2, wherein the second load is a vehicle room temperature control device. The controller is
Increasing the threshold when the power consumption of the first load is less than when large,
The in-vehicle electric system according to any one of claims 1 to 3, wherein control for increasing power consumption of the first load is performed when the relay-off control is started. When the maximum guaranteed current value is the upper limit value of the current allowed to flow through the relay,
The minimum value of the threshold is
5. The current value is set to a value that does not exceed the maximum guaranteed current value when the required driving force of the generator with a motor function maintains a maximum inclination within the required time for off. The vehicle-mounted electrical system in any one. The in-vehicle electric system according to any one of claims 1 to 5, further comprising a diode connected in parallel to the relay and configured to flow current from the second battery side to the first battery side. Relay,
A first battery and a second battery connected in parallel via the relay;
A first load connected in parallel with the first battery without the relay;
A generator with a motor function connected in parallel with the second battery without going through the relay;
A vehicle-mounted electrical system comprising: a controller that acquires information indicating the required driving force of the generator with motor function and performs relay-off control that switches the relay to an OFF state based on the magnitude of the required driving force.

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