JP2020124060A - Vehicular power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize backup of power supply to an auxiliary machine without adding a dedicated power source for backing up the auxiliary machine. SOLUTION: The high voltage battery 30 is a first minute battery 30A composed of a part of the battery cells C on the positive electrode terminal side of the high voltage battery 30 among the plurality of battery cells C, and another of the plurality of battery cells C. It is composed of a second battery 30B composed of a battery cell C. A first DCDC converter 31 that converts the output voltage of the first minute battery 30A into a voltage and outputs it to the auxiliary machine 41 is connected to the first minute battery 30A. A second DCDC converter 32 that converts the output voltage of the second battery 30B into a voltage and outputs the voltage to the auxiliary machine 41 is connected to the second battery 30B. The second battery 30B is connected to the protective auxiliary machine 41P of the auxiliary machines 41 without going through the first DCDC converter 31 and the second DCDC converter 32. [Selection diagram] Fig. 1

Description

The present invention relates to a power supply circuit for a vehicle.

Patent Document 1 discloses a power supply circuit applied to a hybrid vehicle including a motor generator as a drive source. The power supply circuit is provided with a high-voltage battery that exchanges electric power with the motor generator. A DCDC converter is connected to the high voltage battery to step down and output the output voltage of the high voltage battery. A low-voltage battery whose voltage is lower than that of the high-voltage battery is connected to the output side of the DCDC converter. Further, various auxiliary devices such as a vehicle interior light are connected to the output side of the DCDC converter and the low voltage battery. These auxiliary machines operate by receiving power supply from a DCDC converter or a low voltage battery.

JP, 2009-261091, A

In the vehicle power supply circuit as disclosed in Patent Document 1, it is conceivable to connect a backup power source to the auxiliary machine so that the auxiliary machine can operate even when the power supply from the DCDC converter or the low voltage battery is cut off. However, adding a power supply dedicated for backup is not preferable because it secures a space for installing the power supply and increases cost.

In order to solve the above problems, the present invention receives a high-voltage battery composed of a plurality of battery cells connected in series, a low-voltage battery whose voltage is lower than that of the high-voltage battery, and a power supply from the low-voltage battery. A vehicle power supply circuit including an operating auxiliary device, wherein the high-voltage battery is a first distribution battery including a part of battery cells on a positive electrode terminal side of the high-voltage battery among the plurality of battery cells, and A second divided battery composed of another battery cell of the plurality of battery cells, wherein the first divided battery converts the output voltage of the first divided battery into a voltage and outputs the voltage to the auxiliary device. A 1DCDC converter is connected, a second DCDC converter that converts the output voltage of the second split battery and outputs the voltage to the auxiliary device is connected to the second split battery, and the first split battery and the second split battery are connected. Among the batteries, the one whose output voltage is closer to the output voltage of the low-voltage battery is connected to the auxiliary device without passing through the first DCDC converter and the second DCDC converter.

According to the above configuration, in normal times when no abnormality has occurred, the auxiliary device operates by receiving power supply from any of the low voltage battery, the first DCDC converter, and the second DCDC converter. Even if the low-voltage battery, the first DCDC converter, and the second DCDC converter all malfunction and cannot receive power from them, the output voltage of the first and second sub-cells is low. Electric power can be supplied from the battery that is closer to the output voltage of the battery. That is, according to the above configuration, a part of the battery cells forming the high voltage battery functions as a backup power source for the auxiliary equipment. Therefore, the backup of the power supply to the auxiliary machine can be realized without adding a dedicated power source for the backup of the auxiliary machine.

1 is a schematic configuration diagram of a hybrid system and a power supply circuit according to a first embodiment. The schematic block diagram of the power supply circuit in 2nd Embodiment. The schematic block diagram of the power supply circuit in the example of a change.

<First Embodiment>
A first embodiment in which the vehicle power supply circuit of the present invention is applied to a hybrid system of a hybrid vehicle will be described. As shown in FIG. 1, the hybrid system includes an engine 10 as a drive source of the vehicle. The crankshaft 10a of the engine 10 is drivingly connected to the drive wheels via the transmission 11 and the like. The crankshaft 10 a of the engine 10 is drivingly connected to the first pulley 12. A transmission belt 13 is wound around the first pulley 12. Although illustration is omitted, the crankshaft 10a of the engine 10 is also drivingly connected to a hydraulic pump for generating hydraulic pressure, a compressor of an air conditioner, and the like via a belt, a pulley, a gear (sprocket), a chain, and the like. There is.

The hybrid system includes a motor generator 20 as a drive source separate from the engine 10. The motor generator 20 is a so-called three-phase AC motor. The output shaft 20a of the motor generator 20 is drivingly connected to the second pulley 14. The transmission belt 13 is wound around the second pulley 14. That is, the motor generator 20 is drivingly connected to the crankshaft 10 a of the engine 10 via the second pulley 14, the transmission belt 13, and the first pulley 12.

When the motor generator 20 functions as an electric motor, it gives a rotational torque to the second pulley 14, and the rotational torque is input to the crankshaft 10 a of the engine 10 via the transmission belt 13 and the first pulley 12. That is, in this case, the motor generator 20 assists the driving of the engine 10. On the other hand, when the motor generator 20 functions as a generator, the rotational torque of the crankshaft 10 a of the engine 10 is output from the motor generator 20 via the first pulley 12, the transmission belt 13, and the second pulley 14. It is input to the axis 20a. Then, the motor generator 20 generates electric power according to the rotation of the output shaft 20a.

A DC power supply circuit PS is connected to the motor generator 20 via an inverter 21. The inverter 21 is a so-called bidirectional inverter, which converts the AC voltage generated by the motor generator 20 into a DC voltage and outputs the DC voltage to the power supply circuit PS, and converts the DC voltage from the power supply circuit PS into an AC voltage to generate the motor generator 20. Output to. In FIG. 1, the inverter 21 is illustrated as being separate from the motor generator 20, but the inverter 21 may be built in the housing of the motor generator 20.

The power supply circuit PS includes a high voltage battery 30 configured by connecting a plurality of battery cells C (unit cells) in series. The nominal output voltage of the entire high voltage battery 30 is 48 to 52V. In this embodiment, the high voltage battery 30 is a lithium ion secondary battery.

The high voltage battery 30 is divided into a first distribution battery 30A composed of a part of the battery cells C on the positive electrode terminal side and a second distribution battery 30B composed of another battery cell C on the negative electrode terminal side. The first auxiliary battery 30A and the second auxiliary battery 30B are connected in series. The number of battery cells C forming each of the divided batteries is determined so that the nominal output voltage of the second divided battery 30B is close to 12V and the nominal output voltage of the first divided battery 30A is close to 36V. In this embodiment, the number of battery cells C of the second secondary battery 30B is set so that the nominal output voltage of the second secondary battery 30B exceeds 12V and is closest to 12V. The nominal output voltage of is about 13 to 15V.

Although illustration is omitted, the first auxiliary battery 30A has a built-in sensor that detects a current value flowing between the terminals of the first auxiliary battery 30A and a voltage value between the terminals. The sensor of the first auxiliary battery 30A outputs the detected value of the current value or the voltage value as the first auxiliary battery information IF1. Similarly, the second auxiliary battery 30B has a built-in sensor that detects a current value flowing between the terminals of the second auxiliary battery 30B and a voltage value between the terminals. The sensor of the second secondary battery 30B outputs the detected value of the current value or the voltage value as the second secondary battery information IF2.

The positive terminal of the first battery 30A is connected to the inverter 21 via the first relay R1 that switches between electrical conduction and interruption. In addition, the negative terminal of the second battery 30B is connected to the inverter 21 via the second relay R2 that switches between electrical conduction and interruption. That is, the inverter 21 sends and receives electric power to and from the entire high-voltage battery 30 including the first divided battery 30A and the second divided battery 30B.

The positive terminal of the first distribution battery 30A is connected to the high-potential-side input terminal of the first DCDC converter 31 via the above-described first relay R1. The negative terminal of the first distribution battery 30A is connected to the input terminal on the low potential side of the first DCDC converter 31 via the third relay R3 that switches between electrical conduction and interruption. Therefore, the potential difference according to the output voltage of the first battery 30A is input to the first DCDC converter 31. The first DCDC converter 31 is a step-down converter and steps down the input of the potential difference according to the output voltage of the first distribution battery 30A to a potential difference of 12 to 14 V and outputs it.

The output terminal on the low potential side of the first DCDC converter 31 is connected to the ground line. The positive terminal of the low voltage battery 40 is connected to the high-potential-side output terminal of the first DCDC converter 31. The negative terminal of the low voltage battery 40 is connected to the ground line. The low voltage battery 40 is a lead acid battery, and its nominal output voltage is about 12V.

A plurality of auxiliary machines 41 are connected to the high-potential-side output terminal of the first DCDC converter 31 in parallel with the low-voltage battery 40. That is, the positive electrode terminal of each auxiliary device 41 is connected to the positive electrode terminal of the low voltage battery 40, and the negative electrode terminal of each auxiliary device 41 is connected to the ground line. A part of the plurality of auxiliaries 41 is treated as a protection auxiliaries 41P that is protected so that it can function even when the power supply from the first DCDC converter 31, the low voltage battery 40, etc. is cut off. There is. Further, the protection auxiliary device 41P is configured such that the normal operating voltage includes the nominal output voltage of the second secondary battery 30B. In FIG. 1, only two auxiliary machines 41 are shown. Further, one of the two auxiliary machines 41 is shown as a protective auxiliary machine 41P.

The positive terminal of the second secondary battery 30B is connected to the high-potential-side input terminal of the second DCDC converter 32 via the third relay R3 described above. Further, the negative terminal of the second distribution battery 30B is connected to the low-potential-side input terminal of the second DCDC converter 32 via the second relay R2 described above. Therefore, the potential difference is input to the output voltage of the second battery 30B in the second DCDC converter 32. The second DCDC converter 32 is a step-down converter, which steps down the input of the potential difference corresponding to the output voltage of the second distribution battery 30B to a potential difference of 12 to 14 V and outputs it.

The output terminal on the low potential side of the second DCDC converter 32 is connected to the ground line. To the output terminal on the high potential side of the second DCDC converter 32, the positive terminal of the low voltage battery 40 and the positive terminal of each auxiliary machine 41 including the protective auxiliary machine 41P are connected.

The positive terminal of the second auxiliary battery 30B is connected to the positive terminal of the protection accessory 41P via the third relay R3 described above and not via the first DCDC converter 31 and the second DCDC converter 32. That is, the positive terminal of the second secondary battery 30B is directly connected to the protection auxiliary device 41P without a voltage conversion mechanism or the like. In this embodiment, the positive terminal to which the second auxiliary battery 30B is directly connected and the positive terminal to which the first DCDC converter 31 and the second DCDC converter 32 are connected are different terminals in the protection accessory 41P. There is. Then, the protective auxiliary device 41P has a built-in rectifier circuit so that current does not flow from one positive electrode terminal to the other positive electrode terminal.

The first relay R1, the second relay R2, the third relay R3, the first DCDC converter 31, and the second DCDC converter 32 in the power supply circuit PS are controlled by the electronic control device 50.

First battery information IF1 is input to electronic control unit 50 from a sensor incorporated in first battery 30A. The electronic control unit 50 calculates the charge capacity of the first auxiliary battery 30A based on the first auxiliary battery information IF1. Note that the charge capacity here indicates the ratio of the current charge amount to the charge amount when fully charged, and is calculated as a percentage, for example. In addition, the second battery information IF2 is input to the electronic control unit 50 from a sensor incorporated in the second battery 30B. The electronic control unit 50 calculates the charge capacity of the second secondary battery 30B based on the second secondary battery information IF2.

The electronic control unit 50 outputs the first control signal S1 for controlling the operation of the first DCDC converter 31 based on the calculated charge capacity of the first auxiliary battery 30A and the calculated charge capacity of the second auxiliary battery 30B. Output to. Similarly, the electronic control unit 50 outputs the second control signal S2 for controlling the operation of the second DCDC converter 32 based on the calculated charge capacity of the first auxiliary battery 30A and the calculated charge capacity of the second auxiliary battery 30B. To do.

The electronic control unit 50 outputs to the first relay R1 a first switching signal SW1 for switching between electrical conduction and interruption of the first relay R1. In addition, the electronic control unit 50 outputs a second switching signal SW2 for switching between electrical conduction and interruption of the second relay R2 to the second relay R2 and switches electrical conduction and interruption of the third relay R3. And outputs a third switching signal SW3 for switching to the third relay R3. The electronic control unit 50 controls each relay according to the presence/absence of an abnormality in the power supply circuit PS and the location of the abnormality.

The operation and effect of the first embodiment will be described.
First, a case where no abnormality has occurred in the power supply circuit PS and the power supply circuit PS is functioning normally will be described. When no abnormality is detected in the power supply circuit PS, the electronic control unit 50 switches all of the first relay R1 to the third relay R3 to the conductive state through the first switching signal SW1 to the third switching signal SW3. In this state, the power from the low voltage battery 40, the power from the first distribution battery 30A via the first DCDC converter 31 and the second power via the second DCDC converter 32 are supplied to each of the auxiliary devices 41 including the protection auxiliary device 41P. Electric power is supplied from the distribution battery 30B. Further, in addition to these, the protective auxiliary equipment 41P of each auxiliary equipment 41 is supplied with electric power from the second distribution battery 30B without passing through the first DCDC converter 31 and the second DCDC converter 32. Therefore, four systems of power can be supplied to the protection accessory 41P.

When no abnormality is detected in the power supply circuit PS, the electronic control unit 50 controls the first DCDC converter 31 and the second DCDC converter 32 through the first control signal S1 and the second control signal S2. Specifically, the electronic control unit 50 compares the charging capacity of the first auxiliary battery 30A and the charging capacity of the second auxiliary battery 30B to determine which is larger. Then, the electronic control unit 50 controls the output voltage of the first DCDC converter 31 to be higher than the output voltage of the second DCDC converter 32 when the charging capacity of the first battery 30A is larger. As a result, the rate of decrease of the charge capacity of the first auxiliary battery 30A becomes larger than the rate of decrease of the charge capacity of the second auxiliary battery 30B, and the charge capacity of the first auxiliary battery 30A approaches the charge capacity of the second auxiliary battery 30B. To go. On the other hand, the electronic control device 50 controls the output voltage of the second DCDC converter 32 to be higher than the output voltage of the first DCDC converter 31 when the charging capacity of the second battery 30B is larger. As a result, the rate of decrease of the charge capacity of the second auxiliary battery 30B becomes larger than the rate of decrease of the charge capacity of the first auxiliary battery 30A, and the charge capacity of the second auxiliary battery 30B approaches the charge capacity of the first auxiliary battery 30A. To go.

Next, a case where an abnormality has occurred in the power supply circuit PS will be described for each abnormality occurrence location. In addition, unless otherwise noted, it is assumed that the first relay R1 to the third relay R3 are controlled to be in the conductive state as in the case where no abnormality occurs.

-When the low-voltage battery 40 has an abnormality When the low-voltage battery 40 has an abnormality, electric power from the low-voltage battery 40 is not supplied to each auxiliary machine 41 including the protection auxiliary machine 41P. On the other hand, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with electric power from the first divided battery 30A via the first DCDC converter 31 and electric power from the second divided battery 30B via the second DCDC converter 32. It In addition to these, the power from the second distribution battery 30B is supplied to the protection auxiliary device 41P of each auxiliary device 41 without passing through the first DCDC converter 31 and the second DCDC converter 32. Therefore, the protection auxiliary device 41P is operable.

-When there is an abnormality in the high voltage battery 30 When an abnormality occurs in the high voltage battery 30, the electronic control unit 50 switches the first relay R1 and the second relay R2 through the first switching signal SW1 and the second switching signal SW2. Switch to the cutoff state. As a result, the high voltage battery 30 is in a state of being disconnected from the power supply circuit PS. In this state, electric power from the first auxiliary battery 30A and the second auxiliary battery 30B is not supplied to each auxiliary device 41 including the protective auxiliary device 41P. On the other hand, electric power from the low voltage battery 40 is supplied to each of the auxiliary machines 41 including the protective auxiliary machine 41P. Therefore, the protection auxiliary device 41P is operable.

When there is an abnormality in the conductive path from the first distribution battery 30A to the auxiliary device 41 via the first DCDC converter 31, and the conductive path from the second distribution battery 30B to the auxiliary device 41 via the second DCDC converter 32 As described above When such an abnormality occurs, at least one of the electric power from the first auxiliary battery 30A and the electric power from the second auxiliary battery 30B is not supplied to each auxiliary device 41 including the protective auxiliary device 41P. Depending on the location of the abnormality, for example, when the abnormality occurs immediately before the positive electrode terminal of the accessory 41, the accessory 41 is not supplied with power from the low voltage battery 40. On the other hand, the second secondary battery 30B is connected to the protection auxiliary device 41P independently of the above wirings. Therefore, electric power is supplied to the protective auxiliary device 41P from the second battery 30B, and the protective auxiliary device 41P can operate.

When there is an abnormality in the conductive path from the second battery 30B to the protective auxiliary equipment 41P directly without passing through each DCDC converter When the above abnormality occurs, the electronic control unit 50 The third relay R3 is switched to the cutoff state through the third switching signal SW3. As a result, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with electric power from the first auxiliary battery 30A via the first DCDC converter 31 and electric power from the second auxiliary battery 30B via the second DCDC converter 32. It will not be done. Further, since there is an abnormality in the wiring from the second auxiliary battery 30B directly to the auxiliary equipment 41, the direct electric power from the second auxiliary battery 30B is not supplied. On the other hand, electric power from the low voltage battery 40 is supplied to each of the auxiliary machines 41 including the protective auxiliary machine 41P. Therefore, the protection auxiliary device 41P is operable.

As described above, according to the power supply circuit PS of the first embodiment, even if various abnormalities occur in the power supply circuit PS, power can be supplied to the protection auxiliary device 41P, and the operation of the protection auxiliary device 41P can be performed. It can be continued. Moreover, in the power supply circuit PS of the first embodiment, the second secondary battery 30B of the high-voltage battery 30 also functions as a backup power supply for the protection accessory 41P. Therefore, backup of the power supply to the protection auxiliary device 41P can be realized without adding a dedicated power source for backup of the protection auxiliary device 41P.

<Second Embodiment>
A second embodiment in which the vehicle power supply circuit of the present invention is applied to a hybrid system of a hybrid vehicle will be described. In the following description, the same members as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. Further, the connection relationship between the first distribution battery 30A and the first DCDC converter 31, the connection relationship between the second distribution battery 30B and the second DCDC converter 32, and the connection relationship between the first DCDC converter 31, the auxiliary device 41, and the low-voltage battery 40 are: The description is omitted because it is the same as the first embodiment.

As shown in FIG. 2, the high-potential-side input terminal and the high-potential-side output terminal of the second DCDC converter 32 are connected via a diode 61. The diode 61 is connected so as to allow a current flow from the input side to the output side of the second DCDC converter and block a current flow from the output side to the input side. Thereby, the positive terminal of the second distribution battery 30B is connected to the output side of the second DCDC converter 32 not via the first DCDC converter 31 and the second DCDC converter 32 but via the third relay R3 and the diode 61. ..

The high-potential-side output terminal of the second DCDC converter 32 is connected to the positive terminal of the low-voltage battery 40 and the positive terminal of the auxiliary device 41 via a fourth relay R4 that switches between electrical conduction and interruption. That is, the low-voltage battery 40 and each auxiliary device 41 are connected in parallel to the high-potential-side output terminal of the second DCDC converter 32.

The connection node N1 between the high-potential-side output terminal of the second DCDC converter 32 and the fourth relay R4 is connected to the positive terminal of the protection accessory 41P. That is, the high-potential-side output terminal of the second DCDC converter 32 is connected to the positive electrode terminal of the protection auxiliary device 41P without passing through the fourth relay R4. Note that, similarly to the above-described first embodiment, the positive electrode terminal of the protection auxiliary device 41P to which the second DCDC converter 32 is connected is different from the positive electrode terminal of the protection auxiliary device 41P to which the first DCDC converter 31 and the like are connected. It has become a terminal.

The operation and effect of the second embodiment will be described.
First, a case where no abnormality has occurred in the power supply circuit PS and the power supply circuit PS is functioning normally will be described. When no abnormality is detected in the power supply circuit PS, the electronic control unit 50 switches all the first relays R1 to R4 to the conductive state through the first switching signal SW1 to the fourth switching signal SW4. In this state, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with the electric power from the low voltage battery 40 and the electric power from the first distribution battery 30A via the first DCDC converter 31. Further, the electric power from the second distribution battery 30B via the second DCDC converter 32 and the electric power from the second distribution battery 30B not via the second DCDC converter 32 merge at the output side of the second DCDC converter 32, and the merged power is , And is supplied to each auxiliary device 41 via the fourth relay R4. In addition to these, the power from the second auxiliary battery 30B, which has merged at the output side of the second DCDC converter 32, directly flows into the protection auxiliary device 41P of each auxiliary device 41 without passing through the fourth relay R4. Supplied. Therefore, four lines of power can be supplied to the protection accessory 41P. Note that the control of the first DCDC converter 31 and the second DCDC converter 32 in the second embodiment is the same as that in the first embodiment, so a description thereof will be omitted.

Next, a case where an abnormality has occurred in the power supply circuit PS will be described for each abnormality occurrence location. Unless otherwise specified, the first relay R1 to the fourth relay R4 are controlled to be in the conductive state, as in the case where no abnormality has occurred.

-When the low-voltage battery 40 has an abnormality When the low-voltage battery 40 has an abnormality, electric power from the low-voltage battery 40 is not supplied to each auxiliary machine 41 including the protection auxiliary machine 41P. On the other hand, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with electric power from the first auxiliary battery 30A via the first DCDC converter 31. Further, the electric power from the second distribution battery 30B via the second DCDC converter 32 and the electric power from the second distribution battery 30B not via the second DCDC converter 32 merge at the output side of the second DCDC converter 32, and the merged power is , And is supplied to each auxiliary device 41 via the fourth relay R4. In addition to these, the power from the second auxiliary battery 30B, which has merged at the output side of the second DCDC converter 32, directly flows into the protection auxiliary device 41P of each auxiliary device 41 without passing through the fourth relay R4. Supplied. Therefore, the protection auxiliary device 41P is operable.

-When there is an abnormality in the high voltage battery 30 When an abnormality occurs in the high voltage battery 30, the electronic control unit 50 switches the first relay R1 and the second relay R2 through the first switching signal SW1 and the second switching signal SW2. Switch to the cutoff state. As a result, the high voltage battery 30 is in a state of being disconnected from the power supply circuit PS. In this state, electric power from the first auxiliary battery 30A and the second auxiliary battery 30B is not supplied to each auxiliary device 41 including the protective auxiliary device 41P. On the other hand, electric power from the low voltage battery 40 is supplied to each of the auxiliary machines 41 including the protective auxiliary machine 41P. Therefore, the protection auxiliary device 41P is operable.

If there is an abnormality in the wiring from the first battery 30A to the auxiliary equipment 41 via the first DCDC converter 31, or the wiring from the connection node N1 to the auxiliary equipment 41 via the fourth relay R4, the above-mentioned abnormality occurs. In this case, at least one of the electric power from the first auxiliary battery 30A and the electric power from the second auxiliary battery 30B is not supplied to each auxiliary device 41 including the protective auxiliary device 41P. Depending on the location of the abnormality, for example, when the abnormality occurs immediately before the positive electrode terminal of the accessory 41, the accessory 41 is not supplied with power from the low voltage battery 40. On the other hand, the output terminal of the second DCDC converter 32 is independently connected to the protection auxiliary device 41P without the fourth relay R4. Therefore, the protective auxiliary device 41P is supplied with the electric power from the second auxiliary battery 30B, and the protective auxiliary device 41P can operate.

When Abnormality Occurs in the Second DCDC Converter 32 When an abnormality occurs in the second DCDC converter 32, each auxiliary machine 41 including the protective auxiliary machine 41P has a second DC battery 30B via the second DCDC converter 32. The power will not be supplied. On the other hand, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with the electric power of the first distribution battery 30A and the electric power from the low-voltage battery 40 via the first DCDC converter 31. In addition, since the second auxiliary battery 30B is connected to the output side of the second DCDC converter 32 without passing through the second DCDC converter 32, the second auxiliary battery 41P among the plurality of auxiliary devices 41 has a second auxiliary battery 41P. Electric power from the battery 30B is directly supplied. Therefore, the protection auxiliary device 41P is operable.

When there is an abnormality in the conductive path from the second battery 30B to the second auxiliary DCDC converter 32 and directly to the protection auxiliary equipment 41P without passing through the fourth relay R4. The electronic control unit 50 switches the third relay R3 to the cutoff state through the third switching signal SW3. As a result, each auxiliary machine 41 including the protective auxiliary machine 41P is supplied with electric power from the first auxiliary battery 30A via the first DCDC converter 31 and electric power from the second auxiliary battery 30B via the second DCDC converter 32. It will not be done. In addition, the electric power from the second battery 30B that does not pass through the second DCDC converter 32 is not supplied. On the other hand, electric power from the low voltage battery 40 is supplied to each of the auxiliary machines 41 including the protective auxiliary machine 41P. Therefore, the protection auxiliary device 41P is operable.

As described above, according to the power supply circuit PS of the second embodiment, even if various abnormalities occur in the power supply circuit PS, power can be supplied to the protection auxiliary device 41P, and the operation of the protection auxiliary device 41P can be performed. It can be continued. Moreover, in the power supply circuit PS of the second embodiment, the second secondary battery 30B of the high-voltage battery 30 also functions as a backup power source for the protection accessory 41P. Therefore, backup of the power supply to the protection auxiliary device 41P can be realized without adding a dedicated power source for backup of the protection auxiliary device 41P.

Each embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
The configuration of the hybrid system in each of the above embodiments is an example, and can be changed as appropriate. For example, the output shaft 20a of the motor generator 20 may be arranged coaxially with the crankshaft 10a of the engine 10, and both may be connected via a clutch or the like. Further, the crankshaft 10a of the engine 10 and the output shaft 20a of the motor generator 20 may be drivingly connected via a gear mechanism or the like. That is, as long as it is a hybrid system using the engine 10 and the motor generator 20 as a drive source, the technology relating to the power supply circuit PS of each of the above-described embodiments can be applied.

The type of the high voltage battery 30 is not limited to the lithium ion secondary battery. The high-voltage battery 30 may be any rechargeable battery, and may be, for example, a lead storage battery or a nickel-hydrogen storage battery.

The output voltage of the high voltage battery 30 can be changed as appropriate as long as it is higher than the output voltage of the low voltage battery 40. For example, the nominal output voltage of the high voltage battery 30 may be 24V or several hundreds of volts.

-The output voltage of the 1st divisional battery 30A and the 2nd divisional battery 30B which comprise the high voltage battery 30 can also be changed. For example, the nominal output voltage of secondary battery 30B may be correspondingly higher than the nominal output voltage of low voltage battery 40. If the protection auxiliary device 41P can withstand the output voltage of the second auxiliary battery 30B, the output voltage of the second auxiliary battery 30B may be directly supplied to the protection auxiliary device 41P, for example, a resistor or the like. Alternatively, the voltage may be adjusted by interposing the above, and then the voltage may be supplied to the protection auxiliary device 41P. Further, the nominal output voltage of second secondary battery 30B may be lower than the nominal output voltage of low voltage battery 40. In this case, the second DCDC converter 32 may be configured as a boost converter that boosts the output voltage of the second distribution battery 30B to about 12V and outputs the boosted voltage.

When the nominal output voltage of the first divided battery 30A is closer to the nominal output voltage of the low-voltage battery 40 among the first divided battery 30A and the second divided battery 30B, the positive terminal of the first divided battery 30A is It suffices to connect to the protection accessory 41P without the first DCDC converter 31 and the second DCDC converter 32.

The type of the low voltage battery 40 is not limited to the lead storage battery. The low-voltage battery 40 may be a rechargeable battery, and may be, for example, a lithium ion secondary battery or a nickel-hydrogen storage battery. The low voltage battery 40 may be of the same type as the high voltage battery 30.

-The nominal output voltage of the low voltage battery 40 can also be changed. The nominal output voltage of the low-voltage battery 40 may be 24V, 48V, or higher, as long as it is lower than the nominal output voltage of the high-voltage battery 30.

-In each embodiment, the 1st DCDC converter 31 was connected to each auxiliary machine 41 including protective auxiliary machine 41P, but if connected to at least protective auxiliary machine 41P, it will connect to some auxiliary machines 41. It does not have to be. Specifically, in the example shown in FIG. 3, the high-potential-side output terminal of the first DCDC converter 31 is connected to the positive electrode terminal of the protective auxiliary equipment 41P of the auxiliary equipment 41, and the output terminal of the other auxiliary equipment 41. Not connected to the positive terminal. On the other hand, the positive terminal of the second auxiliary battery 30B is connected to the positive terminal of each auxiliary machine 41 including the protective auxiliary machine 41P via the third relay R3 and the diode 61. Therefore, the auxiliary machine 41 to which the first DCDC converter 31 is not connected is supplied with the electric power from the second battery 30B, and the auxiliary machine 41 can operate. Further, in the protection auxiliary device 41P, for example, even if the power supply from the first auxiliary battery 30A via the first DCDC converter 31 is cut off, it is possible to receive the electric power from the second auxiliary battery 30B. Therefore, the backup of the power supply to the protection auxiliary equipment 41P can be realized. As described above, in addition to the power supply path from the first distribution battery 30A via the first DCDC converter 31 to the protection auxiliary device 41P, the protection auxiliary device 41P from the second distribution battery 30B does not include each DCDC converter. It suffices if a power supply route leading to is secured.

The circuit configuration of the power supply circuit PS described in the first embodiment, the second embodiment, and the modification example is merely a conceptual illustration, and a resistor for voltage adjustment, a backflow prevention, and the like may be provided as necessary. It is sufficient to add a diode, a relay for switching between electrical conduction and interruption, and the like.

-The control mode of each relay described in the first and second embodiments can be changed. It suffices if at least a path capable of supplying electric power to the protection accessory 41P is secured. However, it is preferable that each relay be controlled so that the location where the abnormality occurs is separated from the power supply path leading to the protection accessory 41P as much as possible.

10... Engine, 10a... Crankshaft, 11... Transmission, 12... First pulley, 13... Transmission belt, 20... Motor generator, 20a... Output shaft, 21... Inverter, 30... High voltage battery, 30A... First minute battery, 30B...Second battery, 31...First DCDC converter, 32...Second DCDC converter, 40...Low voltage battery, 41...Auxiliary equipment, 41P...Protective auxiliary equipment, 50...Electronic control device, 61...Diode, PS...Power supply circuit, C... Battery cell, IF1... First minute battery information, IF2... Second minute battery information, R1... First relay, R2... Second relay, R3... Third relay, N1... Connection node, S1... First control signal , S2... second control signal, SW1... first switching signal, SW2... second switching signal, SW3... third switching signal, SW4... fourth switching signal.

Claims (1)

A high-voltage battery composed of a plurality of battery cells connected in series,
A low-voltage battery whose voltage is lower than that of the high-voltage battery,
A power supply circuit for a vehicle, comprising: an auxiliary device that operates by receiving power supply from the low-voltage battery,
The high-voltage battery includes a first distribution battery including a part of battery cells on a positive electrode terminal side of the high-voltage battery among the plurality of battery cells, and a second battery cell including another battery cell among the plurality of battery cells. Consists of a split battery,
A first DCDC converter that converts the output voltage of the first auxiliary battery into a voltage and outputs the voltage to the auxiliary device is connected to the first auxiliary battery,
A second DCDC converter that converts the output voltage of the second secondary battery and outputs the voltage to the auxiliary device is connected to the second secondary battery,
The one of the first divided battery and the second divided battery whose output voltage is closer to the output voltage of the low-voltage battery is connected to the auxiliary device without passing through the first DCDC converter and the second DCDC converter. The power supply circuit for vehicles characterized by the following.