JP2006188229A - Electric power distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power distribution system capable of reducing unnecessary dark current. <P>SOLUTION: A master CPU (20a) does not immediately transmits an activation signal to a slave CPU (20b) even if it receives a predetermined instruction signal at off of an ignition switch. At this time, electric power required for an electronic control unit (8c) is fed to a converter (10) for feeding a stand-by current. The master CPU (20a) transmits an activation requirement signal to a controller (12) so as to activate an always feed converter (9). The controller (12) transmits an activation finishing signal to the master CPU (20a) after it activates the always feeding converter (9). The master CPU (20a) firstly transmits the activation signal to the slave CPU (20b) after it receives the activation finishing signal. Thereby, all electronic control units (8c-8f) are fed with the electric power from the always feeding converter (9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power distribution system that can be mounted on various vehicles including automobiles, and more particularly to a power distribution system that distributes and supplies power to various electric loads in the vehicle.

  As an example of a conventional vehicle, there is an automobile (that is, a so-called 14V car) equipped with a power supply unit of 14V output having an alternator and a chargeable / dischargeable 12V (volt) battery. The power distribution system applied to the 14V vehicle includes an electrical connection box that receives a high voltage (for example, 14V) power supply from a power supply unit, and a plurality of electrical connection boxes electrically connected to the electrical connection box via a plurality of power lines. With an electronic control unit. Each electronic control unit incorporates a series regulator that receives supply of high-voltage power distributed from the electrical junction box via the power line. In this power distribution system, the high voltage power of the electrical junction box is converted into low voltage (for example, 5V) power by each series regulator acting as voltage conversion means, and the converted low voltage power is converted into each electronic control. It is supplied to a plurality of electrical loads electrically connected to the unit (see Patent Document 1 below).

By the way, in recent years, development of a high-voltage automobile (that is, a so-called 42V car), which is advantageous in fuel efficiency, equipped with a motor / generator and a power supply unit of 42V output having a 36V battery that can be charged / discharged is progressing. When the power distribution system described above is applied to this 42V vehicle, the conversion efficiency is very poor and a large amount of heat is generated. This is mainly because the difference between the input voltage value and the output voltage value of the series regulator is large. Specifically, assuming that the output voltage of the series regulator (that is, the voltage for the electric load) is 5V, for example, the conversion efficiency of the series regulator in a 14V vehicle is calculated by the equation (100% − ((14V−5V) ÷ 14V × 100 %)) Is approximately 35.7%, whereas the conversion efficiency of the series regulator in 42V vehicles is approximately 11.9% according to the calculation formula (100%-((42V-5V) ÷ 42V × 100%)). It becomes. That is, assuming that the output voltage of the series regulator is constant, the higher the input voltage to the series regulator, the lower the conversion efficiency, and this generates heat in each element in the series regulator. Therefore, it is conceivable that a switching regulator is incorporated in each electronic control unit instead of the series regulator as a voltage conversion means having a higher conversion efficiency than the series regulator.
Japanese Patent Laid-Open No. 10-84626

  However, a switching regulator that supplies power to an electric load whose power consumption varies greatly between a start state and a standby state, such as an electronic control unit for a keyless entry system, is used when the electric load is heavy (that is, the load current is large). If it is designed so that the conversion efficiency is improved in the starting state), the conversion efficiency is low when the electrical load is light (that is, in the standby state where the load current is very small). In such a switching regulator, even when a minute load current (that is, a standby current) is supplied to the electric load in the standby state, a large amount of unnecessary dark current is generated due to the poor conversion efficiency. Since consumption is large, it is not preferable. To solve this problem, all electronic control units that require standby current are provided with standby current supply means. When the ignition switch is on (ie, in the start-up state), power is supplied by the switching regulator, and when the ignition switch is off. It is conceivable to provide a power distribution system in which power is supplied by standby current supply means in the standby state.

  However, in such a power distribution system, it is necessary to provide an expensive switching regulator in each electronic control unit, and it is necessary to further provide standby current supply means in all electronic control units that require standby current. However, there is a problem that it becomes an expensive power distribution system.

  FIG. 9 shows a power distribution system disclosed in Japanese Patent Laid-Open No. 10-84626. As shown in FIG. 9, voltage conversion means 52 is provided in an electric connection box 51 that receives a high voltage power supply from a power supply unit 50, and this voltage conversion means 52 converts high voltage power to a low voltage (for example, 5 V). ), And the low-voltage power is distributed and supplied to each electronic control unit 53 in a lump. According to this, since it is sufficient to provide at least one voltage conversion means 52, a low-cost power distribution system can be constructed.

  However, in the conventional power distribution system shown in FIG. 9, when power is supplied to an electric load arranged far from the voltage converting means 52, a voltage drop is likely to occur, and the electric load is not supplied far away. Considering the arrangement of the voltage conversion means 52, the number of voltage conversion means 52 increases as a result, resulting in an increase in cost. Furthermore, the voltage conversion means 52 must be designed so that the output voltage accuracy, temperature characteristics, etc. of the voltage conversion means 52 are matched to the most demanding electric load among a plurality of electric loads. Designing the voltage conversion means to satisfy strict requirements leads to an increase in the cost of the power distribution system.

  In addition, since the output of the voltage conversion means 52 is likely to fluctuate due to an increase or decrease in load current, it is difficult to supply accurate power to a plurality of electric loads. When power is supplied from the voltage conversion means 52 to an electrical load whose power consumption varies greatly between the start state and the standby state, such as an electronic control unit for a keyless entry system, the voltage conversion is performed when the load current is in the start state. When the conversion efficiency of the means 52 is designed to be improved, the conversion efficiency in the standby state where the load current is very small is poor. In such a voltage conversion means 52, even when a small standby current is supplied to the electric load in the standby state, there is a large amount of unnecessary dark current due to the poor conversion efficiency, thereby increasing the power consumption of the battery. Therefore, it is not preferable.

  The present invention has been made in view of the above-described problems, and in particular, an object thereof is to provide a power distribution system that can reduce unnecessary dark current.

In order to achieve the aforementioned object, the power distribution system of the present invention comprises:
A power distribution system for automobiles equipped with a high-voltage power supply unit,
An upstream power distribution unit connected to the power supply unit via a high voltage power line and receiving a high voltage power supply from the power supply unit;
A plurality of intermediate voltage power lines are connected to the upstream power distribution unit, respectively, to receive power supply of an intermediate voltage lower than the high voltage from the upstream power distribution unit, and from the intermediate voltage by the voltage conversion unit A plurality of downstream power distribution units that convert the voltage to a low load voltage and supply electric power to each electric load,
A converter for constant supply, provided in the upstream power distribution unit, for converting the high voltage into the intermediate voltage and supplying electric power of the intermediate voltage to the intermediate voltage power line;
Standby current supply that is connected in parallel to the constant supply converter in the upstream power distribution unit, converts the high voltage to the intermediate voltage, and supplies the intermediate voltage power to one of the plurality of intermediate voltage power lines Converter for
A controller that is provided in the upstream power distribution unit and controls switching of each of the constant supply converter and the standby current supply converter;
A master CPU provided in a downstream power distribution unit capable of supplying power from the standby current supply converter via an intermediate voltage power line, and constituting at least a part of the electric load;
A slave CPU that is provided in a downstream power distribution unit other than the downstream power distribution unit including the master CPU, and forms at least a part of the electric load;
In-vehicle LAN for transmitting signals between the controller, master CPU and slave CPU,
With
The constant supply converter can convert input / output power when the electric load is heavy with higher conversion efficiency than the standby current supply converter, while the standby current supply converter It is possible to perform conversion of input / output power when the power is light with a higher conversion efficiency than the constant supply converter,
The master CPU activates the constant supply converter to the controller in accordance with a predetermined command signal input when the downstream power distribution unit having the master CPU is supplied with power from the standby current supply converter. When the controller receives the start request signal, the controller sends the start signal to the master CPU after starting the constant supply converter instead of the standby current supply converter. Then, the master CPU that has received the activated signal transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with power from the always-supply converter, and the electric load is Each is driven.

Further, the power distribution system of the present invention is as described in claim 2,
A power distribution system for automobiles equipped with a high-voltage power supply unit,
An upstream power distribution unit connected to the power supply unit via a high voltage power line and receiving a high voltage power supply from the power supply unit;
A plurality of intermediate voltage power lines are connected to the upstream power distribution unit, respectively, to receive power supply of an intermediate voltage lower than the high voltage from the upstream power distribution unit, and from the intermediate voltage by the voltage conversion unit A plurality of downstream power distribution units that convert the voltage to a low load voltage and supply electric power to each electric load,
A converter for constant supply, provided in the upstream power distribution unit, for converting the high voltage into the intermediate voltage and supplying electric power of the intermediate voltage to the intermediate voltage power line;
Standby current supply that is connected in parallel to the constant supply converter in the upstream power distribution unit, converts the high voltage to the intermediate voltage, and supplies the intermediate voltage power to one of the plurality of intermediate voltage power lines Converter for
A controller that is provided in the upstream power distribution unit and controls switching of each of the constant supply converter and the standby current supply converter;
A master CPU provided in a downstream power distribution unit capable of supplying power from the standby current supply converter via an intermediate voltage power line, and constituting at least a part of the electric load;
A timer circuit which is connected to the master CPU and stores a predetermined time required for the always-supply converter to change from a stopped state to a started state;
A slave CPU that is provided in a downstream power distribution unit other than the downstream power distribution unit including the master CPU, and forms at least a part of the electric load;
In-vehicle LAN for transmitting signals between the controller, master CPU and slave CPU,
With
The constant supply converter can convert input / output power when the electric load is heavy with higher conversion efficiency than the standby current supply converter, while the standby current supply converter It is possible to perform conversion of input / output power when the power is light with a higher conversion efficiency than the constant supply converter,
The controller activates the constant supply converter instead of the standby current supply converter in accordance with a predetermined command signal input to the controller and the timer circuit when the standby current supply converter is driven. When the command signal is input, the timer circuit counts until the predetermined time is reached, and transmits the activated signal to the master CPU when the predetermined time is reached, and receives the activated signal. The CPU transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with electric power from the constant supply converter and the electric loads are respectively driven.

  Examples of the downstream power distribution unit in the power distribution system according to claim 1 and claim 2 include various lamp lighting electronic control units, centralized door lock system electronic control units, keyless entry system electronic control units, An electronic control unit for a power seat, an electronic control unit for an anti-theft system, etc. These electronic control units must supply power to the standby electric load even when the ignition switch is turned off, for example, and in the conventional power distribution system, unnecessary dark current is generated due to the standby electric load. . The present invention is extremely effective in reducing this unnecessary dark current.

  That is, according to the power distribution system of claim 1, power is supplied from the standby current supply converter only to the downstream power distribution unit having the master CPU among the plurality of downstream power distribution units in which the electric load is in the standby state. What is necessary is just to supply, and since it is not necessary to supply electric power to other downstream electric power distribution parts, an unnecessary dark current can be reduced. When the electrical load is in the standby state as described above, for example, an unlocking operation is performed in a keyless entry system, and a predetermined command signal generated by the unlocking operation is input, so that the master CPU supplies the controller for constant supply to the controller. Sends a start request signal to start, sends a start signal to the master CPU after the controller has started the always-on converter, and the master CPU sends a start signal to the slave CPU, so that all downstream Since the electric power distribution unit is supplied with electric power from the constant supply converter and the electric loads are respectively driven, the electric power supply can be smoothly switched from the standby current supply converter to the constant supply converter. Therefore, the standby current supply converter only has to supply power until the constant supply converter is started only for driving the electric load of the downstream power distribution unit having the master CPU. And unnecessary dark current can be reduced. In addition, the converter for constant supply uses a converter with good input / output power conversion efficiency when the electrical load is heavy, and the converter for standby current supply uses a converter with good input / output power conversion efficiency when the electrical load is light. Therefore, the power consumption of the entire system can be reduced, and unnecessary dark current can be further reduced.

  Further, according to the power distribution system of the second aspect, as in the power distribution system of the first aspect, the downstream side having the master CPU among the plurality of downstream power distribution units in which the electric load is in the standby state. It is only necessary to supply power from the standby current supply converter only to the power distribution unit, and it is not necessary to supply power to other downstream power distribution units, so unnecessary dark current can be reduced. Thus, when the electric load is in the standby state, for example, an unlocking operation is performed in a keyless entry system, and a predetermined command signal generated thereby is directly input to the controller and the timer circuit simultaneously. In response to the input of this command signal, the controller activates the converter for constant supply, but the timer circuit starts counting without immediately activating the master CPU, and when the timer circuit reaches a predetermined time, the timer circuit sends the activated signal to the master CPU. Send. As a result, the downstream power distribution unit having the master CPU is supplied with electric power from the constant supply converter, and the electric load is driven. Then, the master CPU transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with power from the constant supply converter, and the electric loads are respectively driven. Thus, the power supply is smoothly switched from the standby current supply converter to the constant supply converter without any trouble. Therefore, the standby current supply converter does not need to supply power to all the electric loads of the downstream power distribution unit having the master CPU, so that the power capacity of the standby current supply converter can be further reduced and unnecessary dark current can be obtained. Can be further reduced. In addition, the converter for constant supply uses a converter with good input / output power conversion efficiency when the electrical load is heavy, and the converter for standby current supply uses a converter with good input / output power conversion efficiency when the electrical load is light. Therefore, the power consumption of the entire system can be reduced, and unnecessary dark current can be further reduced.

  The power distribution system according to claim 3 is characterized in that the voltage conversion means of each downstream power distribution unit is a series regulator.

  According to the power distribution system of the third aspect, since the series regulator generates and supplies an accurate electric load voltage to each electric load, a strict supply output accuracy is not required for the constant supply converter. Each series regulator should have a temperature characteristic and accuracy required for the electric load in charge.

  According to the power distribution system of the first aspect, power is supplied from the standby current supply converter only to the downstream power distribution unit having the master CPU among the plurality of downstream power distribution units in which the electric load is in the standby state. What is necessary is that it is not necessary to supply power to the other downstream power distribution units, and therefore unnecessary dark current can be reduced. When the electrical load is in the standby state as described above, for example, an unlocking operation is performed in a keyless entry system, and a predetermined command signal generated by the unlocking operation is input, so that the master CPU supplies the controller for constant supply to the controller. Sends a start request signal to start, sends a start signal to the master CPU after the controller has started the always-on converter, and the master CPU sends a start signal to the slave CPU, so that all downstream Since the electric power distribution unit is supplied with electric power from the constant supply converter and the electric loads are respectively driven, the electric power supply can be smoothly switched from the standby current supply converter to the constant supply converter. Therefore, the standby current supply converter only has to supply power until the constant supply converter is started only for driving the electric load of the downstream power distribution unit having the master CPU. And unnecessary dark current can be reduced. In addition, the converter for constant supply uses a converter with good input / output power conversion efficiency when the electrical load is heavy, and the converter for standby current supply uses a converter with good input / output power conversion efficiency when the electrical load is light. Therefore, the power consumption of the entire system can be reduced, and unnecessary dark current can be further reduced.

  Further, according to the power distribution system of the second aspect, as in the power distribution system of the first aspect, the downstream side having the master CPU among the plurality of downstream power distribution units in which the electric load is in the standby state. It is only necessary to supply power from the standby current supply converter only to the power distribution unit, and it is not necessary to supply power to other downstream power distribution units, so unnecessary dark current can be reduced. Thus, when the electric load is in the standby state, for example, an unlocking operation is performed in a keyless entry system, and a predetermined command signal generated thereby is directly input to the controller and the timer circuit simultaneously. When this command signal is input, the controller always starts the converter for supply, but the timer circuit starts counting the time without starting the master CPU immediately, and when the timer circuit reaches a predetermined time, the timer circuit Is transmitted to the master CPU. As a result, the downstream power distribution unit having the master CPU is supplied with electric power from the constant supply converter, and the electric load is driven. Then, the master CPU transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with power from the constant supply converter, and the electric loads are respectively driven. Thus, the power supply is smoothly switched from the standby current supply converter to the constant supply converter without any trouble. Therefore, the standby current supply converter does not need to supply power to all the electric loads of the downstream power distribution unit having the master CPU, so that the power capacity of the standby current supply converter can be further reduced and unnecessary dark current can be obtained. Can be further reduced. In addition, the converter for constant supply uses a converter with good input / output power conversion efficiency when the electrical load is heavy, and the converter for standby current supply uses a converter with good input / output power conversion efficiency when the electrical load is light. Therefore, the power consumption of the entire system can be reduced, and unnecessary dark current can be further reduced.

  According to the power distribution system of the third aspect, since the series regulator generates and supplies an accurate electric load voltage to each electric load, a strict supply output accuracy is not required for the constant supply converter. Each series regulator should have a temperature characteristic and accuracy required for the electric load in charge. In addition, the converter for constant supply uses a converter with good input / output power conversion efficiency when the electrical load is heavy, and the converter for standby current supply uses a converter with good input / output power conversion efficiency when the electrical load is light. Therefore, the power consumption of the entire system can be reduced, and unnecessary dark current can be further reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to the invention will be described in detail with reference to the drawings. 1 to 6 show a first embodiment of the present invention, and in particular, an example in which the present invention is applied to a high-voltage automobile (that is, a so-called 42V car) equipped with a power supply unit of 42V output. FIG. 1 is a block circuit diagram showing a schematic configuration of a power distribution system 1 of the present invention, FIG. 2 is a block circuit diagram showing a main part in the electrical junction box (ie, Junction Block) 7 of FIG. 1, and FIG. FIG. 4 is a diagram showing output waveforms and timing charts for explaining switching of outputs of the constant supply converter 9 and the standby current supply converter 10, FIG. 4 is a characteristic diagram showing conversion efficiency with respect to load current, and FIG. 5 is a diagram of FIG. FIG. 6 is a block circuit diagram for explaining the power distribution system 1 in more detail, and FIG. 6 is a diagram showing an output waveform and a timing chart for explaining the operation of the power distribution system 1 of FIG.

  As shown in FIG. 1, the power distribution system 1 includes a power supply unit 4, and the power supply unit 4 includes a battery 2 that can be charged and discharged and a motor / generator 3 that generates electric power by rotating the engine. The power supply unit 4 supplies a high-voltage power of 42 V to the three blocks 6 a, 6 b, and 6 c through the high-voltage power lines 5. The block 6a corresponds to, for example, an engine room, the block 6b corresponds to, for example, a passenger compartment, and the block 6c corresponds to, for example, a trunk room. In each of the blocks 6a, 6b, and 6c, for example, an electrical junction box that functions as an upstream power distribution unit and a plurality of electronic control units (that is, Electronic Control Units) that function as downstream power distribution units are provided. . In FIG. 1, the electric junction box 7 and the electronic control units 8a, 8b,..., 8n are shown as an example in the block 6b. However, one electrical junction box 7 is provided for all the blocks 6a, 6b, 6c, and the electrical junction box 7 is connected to a plurality of electronic control units in each block 6a, 6b, 6c. May be. The electric connection box 7 incorporates a constant supply converter 9 and a standby current supply converter 10, and both the constant supply converter 9 and the standby current supply converter 10 are led to a high voltage power supply of 42V. ing.

  The constant supply converter 9 is a DC / DC converter (that is, a DC-DC converter) having good conversion efficiency when the electric load is heavy. For example, a switching regulator may be used as the constant supply converter 9. The constant supply converter 9 converts a high-voltage power supply of 42V into an intermediate voltage (for example, 14V) higher than an electric load voltage (for example, 5V). The output of the constant supply converter 9 is supplied to all the electronic control units 8 a to 8 n via the intermediate voltage power line 11. The standby current supply converter 10 uses a DC / DC converter with good conversion efficiency when the electrical load is light. For example, a series regulator may be used as the standby current supply converter 10. The standby current supply converter 10 converts a high-voltage power supply of 42V into an intermediate voltage (for example, 14V) higher than an electric load voltage (for example, 5V). The output of the standby current supply converter 10 is supplied via an intermediate voltage power line 11 to an electronic control unit 8b that must supply power to an electric load in a standby state even when an ignition switch (not shown) is turned off, for example. Examples of such electronic control unit 8b include various lamp lighting electronic control units, centralized door lock system electronic control units, keyless entry system electronic control units, power seat electronic control units, and anti-theft system electronic devices. A control unit, etc.

  As shown in FIG. 2, a controller 12 is built in the electrical connection box 7, and the controller 12 controls the driving of the constant supply converter 9 and the standby current supply converter 10. The controller 12 controls the constant supply converter 9 and the standby current supply converter 10 based on, for example, on / off of an ignition switch (not shown) or the detection output of the current detection sensor 13. The current detection sensor 13 targets the intermediate voltage power line 11 that performs a common output of the converter 9 for continuous supply and the converter 10 for standby current supply.

  Returning to FIG. 1, a plurality of electric loads (not shown) are connected to the electronic control units 8a to 8n, and the electronic control units 8a to 8n control the connected electric loads. Each electronic control unit 8 a to 8 n has a built-in series regulator 14, and an intermediate voltage of 14 V is led from each electrical connection box 7 to each series regulator 14. Each series regulator 14 has a known configuration in which, for example, an operational amplifier is used to feed back fluctuations in the load voltage to stabilize the output voltage, and the intermediate voltage of 14V is converted to an electric load voltage of 5V. The output of each series regulator 14 is supplied to a plurality of electric loads (not shown) that the series regulator 14 takes charge of.

  Here, operation | movement of the electric power distribution system 1 demonstrated above is demonstrated based on FIG. When an ignition switch (not shown) is turned on, the constant supply converter 9 is driven by the control of the controller 12, and the constant supply converter 9 converts the high voltage of 42V of the power supply unit 4 into an intermediate voltage of 14V. The intermediate voltage of 14V is supplied to the electronic control units 8a to 8n, and the series regulator 14 of each electronic control unit 8a to 8n converts the intermediate voltage of 14V into a voltage for electric load of 5V to each electric load (not shown). ).

  When the ignition switch (not shown) is switched from on to off, the load current is gradually reduced, and when the current detection sensor 13 detects that the load current has dropped below the set threshold value (predetermined value), The controller 12 stops the constant supply converter 9 and starts the standby current supply converter 10. As a result, the voltage supply source to the electronic control unit 8b is changed from the constant supply converter 9 to the standby current supply converter 10.

  Incidentally, a large load current may be required even when an ignition switch (not shown) is turned off. For example, a large load current is required for the electronic control unit 8b for starting the central door lock system, starting the keyless entry system, driving the power seat, lighting various lamps, starting the anti-theft system, and the like. When the ignition switch is off, for example, when the current detection sensor 13 detects that a large load current flows due to power seat driving and has risen above the set threshold value, the controller 12 causes the standby current supply converter 10 to operate. Is stopped and the constant supply converter 9 is driven. As a result, the voltage supply source to the electronic control unit 8b is changed from the constant supply converter 9 to the standby current supply converter 10. When the current detection sensor 13 detects that the increased load current has fallen below the threshold value, the controller 12 stops the constant supply converter 9 and the standby current supply converter 10 is driven again.

  When an ignition switch (not shown) is switched from OFF to ON, the controller 12 stops driving the standby current supply converter 10 regardless of the detection current value of the current detection sensor 13, and the constant supply converter 9 is driven. Be started. That is, a voltage is supplied from the constant supply converter 9 to the electronic control units 8a to 8n.

  In this power distribution system 1, the constant supply converter 9 supplies a voltage value (14V) higher than the load voltage value (5V) to the electronic control units 8a to 8n. Therefore, it is only necessary to install a minimum number of converters 9 for continuous supply. In addition, since the series regulator 14 generates and supplies an accurate load voltage to each electric load (not shown), the constant supply converter 9 does not require strict supply output accuracy. Etc. may be small. Since each electronic control unit 8a-8n is provided with a series regulator 14, each series regulator 14 can be prepared with temperature characteristics and accuracy required for the electric load (not shown) in charge. good.

  Therefore, the number of constant supply converters 9 can be reduced, and both the constant supply converter 9 and the standby current supply converter 10 do not require strict supply output accuracy, and moreover, expensive switching is required for each electronic control unit. By using the inexpensive series regulator 14 instead of the regulator, the power distribution system 1 can be configured at low cost. Further, the converter 9 for continuous supply and the converter 10 for supplying standby current in the electrical junction box 7 have a configuration with good conversion efficiency according to the load currents in charge, and the converters 9 and 10 have converted to an intermediate voltage value. Since each of the series regulators 14 converts the voltage into a load voltage value, as shown in FIG. 4, the voltage conversion efficiency and heat generation of the entire system can be improved, and the fuel consumption can be improved.

  Further, since the series regulator 14 generates an accurate load voltage and supplies it to each electric load (not shown), it is not necessary to shield the intermediate voltage power line 11 from the constant supply converter 9 to the series regulator 14. .

  Further, the electrical junction box 7 is provided with a converter 10 for supplying standby current that converts the high voltage power source of the power supply unit 4 into an intermediate voltage when the electrical load is light. Since power is supplied to the electronic control unit 8b by the supply converter 9, since the standby current can be supplied collectively by the standby current supply converter 10 having high conversion efficiency when the electrical load is light, The current is suppressed as much as possible, and the battery can be prevented from running out.

  Further, a current detection sensor 13 for detecting a supply current value from the electrical connection box 7 to each electronic control unit is provided. As a result, when the ignition switch is turned off and the current value detected by the current detection sensor 13 is equal to or greater than a predetermined value, power is supplied with the constant supply converter 9 in the operating state. When the ignition switch is turned off and the current value detected by the current detection sensor 13 is less than a predetermined value, the constant supply converter 9 is stopped and power is supplied only by the standby current supply converter 10. Therefore, since the converters 9 and 10 are switched based on the detected current value of the current detection sensor 13 even when the ignition switch is off, converter switching control based on the actual current value level is possible.

  Further, since the intermediate voltage has a voltage value of 14 V that is lower than the power supply voltage (42 V) and higher than the electric load voltage (5 V), the converter 9 for constant supply with good conversion efficiency when the electric load is heavy causes the electric load voltage. Therefore, the voltage conversion efficiency of the entire system can be improved and the heat generation can be reduced, and the fuel consumption can be improved. The intermediate voltage value is preferably set to any value between 6V and 14V. However, the intermediate voltage value needs to be a voltage value that does not cause inconvenience due to a voltage drop to the remote series regulator 14. When the intermediate voltage value is set so that the difference between the input voltage value and the output voltage value of the series regulator 14 is small, the heat generation of the series regulator 14 can be suppressed small, and the size of the series regulator 14 can be reduced. On the other hand, when the intermediate voltage value is set to 14V as in the present embodiment, a general-purpose electronic control unit can be used as a downstream power distribution unit or a power source for a general-purpose 14V-compatible electrical component. The power distribution system 1 can be configured at a low cost.

  As described above, the electronic control unit 8b in FIG. 1 is an electronic control unit that must supply power to an electric load in a standby state even when, for example, an ignition switch (not shown) is turned off. Therefore, the output of the standby current supply converter 10 is supplied to the electronic control unit 8 b via the intermediate voltage power line 11. The electronic control unit 8b is an electronic control unit in which the power consumption of the electric load changes greatly between the activated state and the standby state. As described above, the current detection sensor 13 detects an increase / decrease in the value of the load current flowing through the intermediate voltage power line 11 with respect to the set threshold value, and the controller 12 and the standby current supply are always supplied by the controller 12 according to the detection result. The drive of the converter 10 can be appropriately switched and controlled. However, when there are a plurality of electronic control units such as the electronic control unit 8b, there is a possibility that a large burden may be imposed by dealing with the power consumption that changes greatly due to the transition of the electric load from the standby state to the activated state even for a moment. In consideration of a certain standby current supply converter 10, in the present invention, standby current supply is performed when switching from the standby current supply converter 10 to the constant supply converter 9 so that the detection by the current detection sensor 13 does not have to be relied upon. The power distribution system 1 is configured so that the converter 10 is not burdened as much as possible. Details of such a power distribution system 1 will be described with reference to FIGS. 5 and 6. Further, reduction of dark current by the power distribution system 1 will be described with reference to FIGS. 5 and 6.

  As shown in FIG. 5, a plurality of electronic control units (that is, Electronic Control Units) 8c to 8f serving as downstream power distribution units are electrically connected to the power supply unit 4 and the electrical connection box 7 serving as an upstream power distribution unit. It is connected. These electronic control units 8c to 8f are electronic control units in which the power consumption of the electric load varies greatly between the activated state and the standby state in the same manner as the electronic control unit 8b in FIG. 1, and the central door lock system 16 and the keyless entry system. FIG. In FIG. 5, the passenger seat ECU corresponds to the electronic control unit 8c, the passenger seat ECU corresponds to the electronic control unit 8d, the rear seat left ECU corresponds to the electronic control unit 8e, and the rear seat right ECU is electronically controlled. It corresponds to the unit 8f. The intermediate voltage power line 11 that performs the common output of the constant supply converter 9 and the standby current supply converter 10 is connected to at least the electronic control unit 8c.

  The controller 12 in the electrical junction box 7 also functions as an electrical junction box ECU for controlling a LAN (ie, a local area network) 18 so that all the electronic control units 8a to 8n are connected to the LAN and can communicate with each other. It has become. A plurality of fuses are inserted in the high voltage power line 5 and the intermediate voltage power line 11 for circuit protection. Each electronic control unit 8c to 8f is provided with a master CPU 20a, a slave CPU 20b, a driver circuit 22, and the like as electric loads. The master CPU 20a is connected to the central door lock system 16 and the keyless entry system 17 via signal lines so as to receive a predetermined command signal generated by the unlock operation in the central door lock system 16 or the unlock operation in the keyless entry system 17. It is connected. The driver circuit 22 drives a motor for performing a lock / unlock operation of the vehicle door according to a command signal from the master CPU 20a or the slave CPU 20b.

  Next, the operation when the ignition switch (not shown) of the power distribution system 1 of FIG. 5 is turned off will be described with reference to FIG. When the ignition switch is off, only the electronic control unit 8c having the master CPU 20a is supplied with power necessary for the standby state from the standby current supply converter 10. Electric power is not supplied to the other electronic control units 8d to 8f. Therefore, unnecessary dark current can be reduced. Even if the master CPU 20a receives a predetermined command signal generated by the unlocking operation in the central door lock system 16 or the unlocking operation in the keyless entry system 17, the master CPU 20a does not immediately transmit an activation signal to the slave CPU 20b. At this time, the electric power necessary for the electronic control unit 8c is supplied by the standby current supply converter 10, and the master CPU 20a transmits a command signal to the driver circuit 22 to drive the motor to perform the door unlocking operation. . Then, the master CPU 20a transmits an activation request signal to the controller 12 via the LAN 18 so as to activate the constant supply converter 9. The controller 12 transmits the activated signal to the master CPU 20a via the LAN 18 after activating the constant supply converter 9. Only after receiving this activated signal, the master CPU 20a transmits an activated signal to the slave CPU 20b via the LAN 18. Thereby, all the electronic control units 8c to 8f are supplied with electric power from the converter 9 for constant supply, and the slave CPU 20b also sends a command signal to the driver circuit 22 to drive the motor to perform the door unlocking operation. In this way, the power supply can be smoothly switched from the standby current supply converter 10 to the constant supply converter 9 without hindrance. Therefore, the standby current supply converter 10 only has to supply power until the constant supply converter 9 is started only for driving the electric load of the electronic control unit 8c having the master CPU 20a. The power capacity can be reduced and unnecessary dark current can be reduced.

  Further, since the series regulator 14 generates and supplies a highly accurate electric load voltage (for example, 5 V) to each electric load, strict supply output accuracy is not required for the constant supply converter 9. Each series regulator 14 may be prepared with temperature characteristics and accuracy required for the electric load in charge. In addition, the constant supply converter 9 adopts a converter with good input / output power conversion efficiency when the electric load is heavy, and the standby current supply converter 10 has good input / output power conversion efficiency when the electric load is light. Since it is employed, the power consumption of the entire power distribution system 1 can be reduced, and unnecessary dark current can be further reduced.

  7 and 8 show a second embodiment of the present invention. FIG. 7 is a block circuit diagram for explaining the power distribution system 1 ′ of the present invention in detail, and FIG. 8 is a diagram showing an output waveform and a timing chart for explaining the operation of the power distribution system 1 ′ of FIG. is there. In the power distribution system 1 ′ of the second embodiment, a timer circuit 24 is newly added as compared with the power distribution system 1 of the first embodiment. The timer circuit 24 is provided in the electronic control unit 8c ′, receives power from the output of the series regulator 14 of the electronic control unit 8c ′, and transmits a started signal to the master CPU 20a via a signal line. Connected. The controller 12 and the timer circuit 24 are connected to the central door lock system 16 and the keyless entry system 17 via signal lines, respectively, so that predetermined command signals can be received from the central door lock system 16 and the keyless entry system 17. The timer circuit 24 stores a predetermined time required for the constant supply converter 9 to reach a fully activated state from a stopped state. The other configuration is substantially the same as the configuration of the first embodiment, and the description thereof is omitted to avoid redundant description. In addition, the same code | symbol as 1st Embodiment is attached | subjected to the same structure location in a figure, and it aims at clarification.

  Next, the operation when the ignition switch (not shown) of the power distribution system 1 ′ in FIG. 7 is turned off will be described with reference to FIG. 8. When the ignition switch is off, only the electronic control unit 8c 'having the master CPU 20a is supplied with power necessary for the standby state from the standby current supply converter 10. Electric power is not supplied to the other electronic control units 8d to 8f. Therefore, unnecessary dark current can be reduced. The controller 12 and the timer circuit 24 simultaneously receive a predetermined command signal generated by the unlocking operation in the central door lock system 16 or the unlocking operation in the keyless entry system 17. When this command signal is received (ie, input), the controller 12 activates the converter 9 for continuous supply, but the timer circuit 24 does not activate the master CPU 20a immediately but starts counting time, and at a minimum, it is predetermined. Count until time. Then, when it reaches a time (that is, a predetermined time) that the converter 9 for continuous supply can be sufficiently activated, the timer circuit 24 transmits an activated signal to the master CPU 20a. As a result, necessary electric power is supplied from the constant supply converter 9 to the electronic control unit 8c 'having the master CPU 20a. The master CPU 20a transmits a command signal to the driver circuit 22 to drive the motor to perform the door unlocking operation. The master CPU 20a transmits an activation signal to the slave CPU 20b via the LAN 18. Thereby, all the electronic control units 8c 'to 8f are supplied with electric power from the converter 9 for continuous supply, and the slave CPU 20b also sends a command signal to the driver circuit 22 to drive the motor to perform the door unlocking operation. In this way, the power supply can be smoothly switched from the standby current supply converter 10 to the constant supply converter 9 without hindrance. Therefore, the standby current supply converter 10 does not need to supply power to all the electric loads of the electronic control unit 8c ′ having the master CPU 20a, so that the power capacity of the standby current supply converter 10 can be further reduced and is unnecessary. Dark current can be further reduced.

  Further, since the series regulator 14 generates and supplies a highly accurate electric load voltage (for example, 5 V) to each electric load, strict supply output accuracy is not required for the constant supply converter 9. Each series regulator 14 may be prepared with temperature characteristics and accuracy required for the electric load in charge. In addition, the constant supply converter 9 adopts a converter with good input / output power conversion efficiency when the electric load is heavy, and the standby current supply converter 10 has good input / output power conversion efficiency when the electric load is light. Since it is employed, the power consumption of the entire power distribution system 1 ′ can be reduced, and unnecessary dark current can be further reduced.

  The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like can be made as appropriate. In addition, the shape, form, number, location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

1 is a block circuit diagram illustrating a schematic configuration of a power distribution system according to a first embodiment of the present invention. It is a block circuit diagram which shows the principal part in the electrical-connection box of FIG. FIG. 3 is a diagram illustrating an output waveform and a timing chart for explaining switching of outputs of a constant supply converter and a standby current supply converter of FIG. 2. It is a characteristic diagram which shows the conversion efficiency with respect to load current. It is a block circuit diagram for demonstrating in more detail 1st Embodiment of the power distribution system of FIG. It is a figure which shows the output waveform and timing chart for demonstrating operation | movement of the power distribution system of FIG. It is a block circuit diagram for demonstrating in detail 2nd Embodiment of the power distribution system of this invention. It is a figure which shows the output waveform and timing chart for demonstrating operation | movement of the electric power distribution system of FIG. It is a figure which shows the electric power distribution system currently disclosed by Unexamined-Japanese-Patent No. 10-84626.

Explanation of symbols

1, 1 'Power distribution system 4 Power supply section 5 High voltage power line 7 Electrical junction box (upstream power distribution section)
8a to 8n Electronic control unit (downstream power distribution unit)
9 Converter for constant supply 10 Converter for standby current supply 11 Intermediate voltage power line 12 Controller 13 Current detection sensor 14 Series regulator 20a Master CPU
20b Slave CPU
24 Timer circuit

Claims (3)

A power distribution system for automobiles equipped with a high-voltage power supply unit,
An upstream power distribution unit connected to the power supply unit via a high voltage power line and receiving a high voltage power supply from the power supply unit;
A plurality of intermediate voltage power lines are connected to the upstream power distribution unit, respectively, to receive power supply of an intermediate voltage lower than the high voltage from the upstream power distribution unit, and from the intermediate voltage by the voltage conversion unit A plurality of downstream power distribution units that convert the voltage to a low load voltage and supply electric power to each electric load,
A converter for constant supply, provided in the upstream power distribution unit, for converting the high voltage into the intermediate voltage and supplying electric power of the intermediate voltage to the intermediate voltage power line;
Standby current supply that is connected in parallel to the constant supply converter in the upstream power distribution unit, converts the high voltage to the intermediate voltage, and supplies the intermediate voltage power to one of the plurality of intermediate voltage power lines Converter for
A controller that is provided in the upstream power distribution unit and controls switching of each of the constant supply converter and the standby current supply converter;
A master CPU provided in a downstream power distribution unit capable of supplying power from the standby current supply converter via an intermediate voltage power line, and constituting at least a part of the electric load;
A slave CPU that is provided in a downstream power distribution unit other than the downstream power distribution unit including the master CPU, and forms at least a part of the electric load;
In-vehicle LAN for transmitting signals between the controller, master CPU and slave CPU,
With
The constant supply converter can convert input / output power when the electric load is heavy with higher conversion efficiency than the standby current supply converter, while the standby current supply converter It is possible to perform conversion of input / output power when the power is light with a higher conversion efficiency than the constant supply converter,
The master CPU activates the constant supply converter to the controller in accordance with a predetermined command signal input when the downstream power distribution unit having the master CPU is supplied with power from the standby current supply converter. When the controller receives the start request signal, the controller sends the start signal to the master CPU after starting the constant supply converter instead of the standby current supply converter. Then, the master CPU that has received the activated signal transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with power from the always-supply converter, and the electric load is A power distribution system, each driven. A power distribution system for automobiles equipped with a high-voltage power supply unit,
An upstream power distribution unit connected to the power supply unit via a high voltage power line and receiving a high voltage power supply from the power supply unit;
A plurality of intermediate voltage power lines are connected to the upstream power distribution unit, respectively, to receive power supply of an intermediate voltage lower than the high voltage from the upstream power distribution unit, and from the intermediate voltage by the voltage conversion unit A plurality of downstream power distribution units that convert the voltage to a low load voltage and supply electric power to each electric load,
A converter for constant supply, provided in the upstream power distribution unit, for converting the high voltage into the intermediate voltage and supplying electric power of the intermediate voltage to the intermediate voltage power line;
Standby current supply that is connected in parallel to the constant supply converter in the upstream power distribution unit, converts the high voltage to the intermediate voltage, and supplies the intermediate voltage power to one of the plurality of intermediate voltage power lines Converter for
A controller that is provided in the upstream power distribution unit and controls switching of each of the constant supply converter and the standby current supply converter;
A master CPU provided in a downstream power distribution unit capable of supplying power from the standby current supply converter via an intermediate voltage power line, and constituting at least a part of the electric load;
A timer circuit which is connected to the master CPU and stores a predetermined time required for the always-supply converter to change from a stopped state to a started state;
A slave CPU that is provided in a downstream power distribution unit other than the downstream power distribution unit including the master CPU, and forms at least a part of the electric load;
In-vehicle LAN for transmitting signals between the controller, master CPU and slave CPU,
With
The constant supply converter can convert input / output power when the electric load is heavy with higher conversion efficiency than the standby current supply converter, while the standby current supply converter It is possible to perform conversion of input / output power when the power is light with a higher conversion efficiency than the constant supply converter,
The controller activates the constant supply converter instead of the standby current supply converter in accordance with a predetermined command signal input to the controller and the timer circuit when the standby current supply converter is driven. When the command signal is input, the timer circuit counts until the predetermined time is reached, and transmits the activated signal to the master CPU when the predetermined time is reached, and receives the activated signal. The CPU transmits an activation signal to the slave CPU, whereby all the downstream power distribution units are supplied with power from the constant supply converter and the electric loads are respectively driven. system.   The power distribution system according to claim 1 or 2, wherein the voltage conversion means of each of the downstream power distribution units is a series regulator.

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