JP2019088085A - Power supply system - Google Patents

Abstract

To provide a power supply system capable of avoiding an unintentional conduction state of a plurality of storage batteries when a system stops.SOLUTION: A power supply system comprises: first and second storage batteries connected in parallel with a generator and an electric load; first and second electric paths connecting the first and second storage batteries; a normally-closed type relay electrically connecting the first storage battery and the electric load; and a switch unit provided on respective electric paths. The switch unit comprise: a first switch provided at a first storage battery side and a second switch provided at a second storage battery side in the first electric path; a third switch provided at the first storage battery side and a fourth switch provided at the second storage battery side in the second electric path. The relay is connected with the third switch in parallel and with the fourth switch in series. The fourth switch of the second and fourth switches at the second storage battery side has a redundant section for interrupting a current flowing between the first and second storage batteries via the relay.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply system mounted on a vehicle or the like.

  As a power supply system mounted on a vehicle, a first storage battery (lead storage battery etc.) and a second storage battery (lithium ion storage battery etc.) are connected in parallel to a generator, and a first storage battery There is a system in which second storage batteries are connected in parallel (for example, Patent Document 1).

  In this on-vehicle power supply system, power is supplied to various electric loads while using two storage batteries properly, or storage batteries are selected to supply power from a generator.

  In such a power supply system, a plurality of semiconductor switches are provided to selectively use two storage batteries. In addition, bypass relays are provided in bypass paths that bypass each switch for dark current supply to the electric load at the time of system stop and fail safe treatment.

  At the time of system operation, by controlling the opening and closing of each switch by the control unit appropriately, the electrical connection state of the generator, the two storage batteries and the electric load is switched. When the system is stopped, the switch is opened to connect the storage battery and the electrical load via the bypass relay.

JP, 2015-93554, A

  Of the switches provided in the electrical path connecting the first storage battery and the second storage battery, when the switch connected in series with the bypass relay becomes unintentionally conductive when the system is stopped, the two storage batteries are electrically connected. I will. At this time, if an unintended current flows due to the potential difference between both storage batteries, overcharging and overdischarging may occur in both storage batteries. In addition, about the switch which is not connected in series with the bypass relay, even if the switch is unintentionally brought into conduction, such an abnormality may be less likely to occur.

  The present invention has been made in view of the above, and it is a main object of the present invention to provide a power supply system capable of preventing a plurality of storage batteries from being unintentionally turned on when the system is stopped.

In the first means, a first storage battery (11) and a second storage battery (12) connected in parallel to the generator (16) and the electric load (15), respectively.
An electrical path connecting the first storage battery and the second storage battery, a first electrical path (L1) and a second electrical path (L2) connected in parallel with each other,
A switch unit (SWU) provided on the first electrical path and the second electrical path to switch the electrical connection between the generator, the storage batteries, and the electrical load;
A normally closed relay (31) electrically connecting the first storage battery and the electrical load;
The switch unit is
A first switch (SW1) provided closer to the first storage battery than a first connection point with the generator in a portion parallel to the second electrical path of the first electrical path;
A second switch (SW2) provided closer to the second storage battery than the first connection point in a portion parallel to the second electrical path of the first electrical path;
A third switch (SW3) provided closer to the first storage battery than a second connection point (N2) with the electric load in a portion parallel to the first electric path in the second electric path;
And a fourth switch (SW4) provided closer to the second storage battery than the second connection point in a portion parallel to the first electrical path in the second electrical path,
The relay is connected in parallel to the third switch, and connected in series to the fourth switch,
Among the second switch and the fourth switch provided on the side of the second storage battery, the fourth switch is a redundancy that cuts off the current flowing between the first storage battery and the second storage battery via the relay. It has a redundant part (SW4a, SW4b, S3) for securing the property.

  When a normally closed relay electrically connecting the first storage battery and the electric load is connected in parallel to the third switch of the second electric path, each switch constituting the switch unit is turned off when the system is stopped Also, since the first storage battery and the electrical load are electrically connected via the relay, power can be supplied to the electrical load.

  However, in the configuration in which such a relay is provided, when the fourth switch connected in series with the relay unintentionally becomes conductive, the first storage battery is relayed via the relay (and the fourth switch). And the second storage battery are electrically connected. At this time, if there is a potential difference between the first storage battery and the second storage battery, an unintended current flows between the two batteries.

  When the system is stopped, the states of the switches constituting the switch unit can not be switched. Therefore, if such an unintended current flows, there is a risk that overcharging and overcharging may occur in both storage batteries. By the way, since the first electrical path is not provided with a normally closed relay for electrically connecting the first storage battery and the electrical load, it is considered that such an abnormality is less likely to occur compared to the second electrical path. .

  Therefore, in order to ensure redundancy for interrupting the current flowing between the first storage battery and the second storage battery via the relay in the fourth switch among the second switch and the fourth switch provided on the side of the second storage battery. Provided a redundant part of

  With such a configuration, it is possible to enhance the function of blocking unintended flow of current between the first storage battery and the second storage battery via the relay when the system is stopped. Further, among the second switch and the fourth switch provided on the side of the second storage battery, only the fourth switch of the second electric path is made to have a redundant portion, so that both the second switch and the fourth switch The configuration can be simplified as compared with the case where the switch has a redundant part.

  In the second means, each of the switches is configured using a semiconductor switch, and the redundant portion is connected in series by connecting the semiconductor switches in the fourth switch more than the second switches. It is provided.

  As described above, by connecting in series the semiconductor switches whose number is larger than that of the second switch, the redundant part can be provided in the fourth switch.

  In the third means, each of the switches is configured using a pair of semiconductor switches, and the pair of semiconductor switches are connected in series so that the directions of the parasitic diodes are opposite to each other. The redundant portion is provided by connecting in series another semiconductor switch to the pair of semiconductor switches on the second electric path side with respect to the connection point.

  When each switch is configured using a pair of semiconductor switches and connected in series so that the directions of the parasitic diodes of the pair of semiconductor switches are opposite to each other, the semiconductor switches can be turned off if the semiconductor switches are turned off. It is also possible to shut off the current component flowing through the switch specific diode component.

  However, if any abnormality occurs in the current interruption function of the switch, the current can not be completely interrupted even if the switch is turned off. Then, in the fourth switch, when such an abnormality occurs, the first storage battery and the second storage battery are in a conducting state, and the influence is the same as in the case where the same abnormality occurs in the other switches. Is considered to be larger.

  Therefore, as for the fourth switch, a redundant portion is provided by connecting another semiconductor switch in series to the pair of semiconductor switches. With such a configuration, even if an abnormality occurs in the current interrupting function of the pair of semiconductor switches in the fourth switch, another semiconductor switch connected in series with the pair of semiconductor switches is connected via the relay. The current flowing between the first storage battery and the second storage battery can be cut off.

  By the above, generation | occurrence | production of the malfunction which an unintended electric current flows between a 1st storage battery and a 2nd storage battery can be suppressed.

  In the fourth means, the semiconductor switch provided as the redundant portion is provided in a direction in which the direction of the parasitic diode cuts off the current flowing from the first storage battery to the second storage battery in the second electric path.

  Among the current flowing between the first storage battery and the second storage battery, the function of interrupting the current flowing from the first storage battery to the second storage battery can be enhanced.

  In a fifth means, the first storage battery is a lead storage battery, and the second storage battery is a lithium ion storage battery.

  It is possible to enhance the blocking function of unintended current flow between the lead storage battery and the lithium ion storage battery.

The electric circuit diagram showing the power supply system of a 1st embodiment. Explanatory drawing of the effect in the power supply system of 1st Embodiment. The electric circuit diagram which shows the power supply system of 2nd Embodiment.

  Hereinafter, embodiments will be described based on the drawings. In each of the following embodiments, in a vehicle traveling with an engine (internal combustion engine) as a drive source, an on-vehicle power supply system for supplying power to various devices of the vehicle is embodied. In addition, in the following each embodiment, the same code | symbol is attached | subjected to the mutually same or equal part in the figure, and the description is used about the part of the same code | symbol.

First Embodiment
As shown in FIG. 1, the power supply system is a dual power supply system having a lead storage battery 11 (first storage battery) and a lithium ion storage battery 12 (second storage battery) connected in parallel to the generator 16 and the electric load 15, respectively. is there.

  Hereinafter, the specific configuration of the power supply system will be described. Of the two storage batteries 11 and 12, the lithium ion storage battery 12 is housed in a housing case (not shown) and configured as a battery unit U integrated with a substrate. The battery unit U has output terminals P1, P2 and P3. Among them, the lead storage battery 11 and the starter 13 are connected to the output terminal P1, the generator 16 is connected to the output terminal P2, and electricity is output to the output terminal P3. The load 15 is connected.

  The electrical load 15 includes a constant voltage required load that is required to be stable so that the voltage of the supplied power fluctuates within a predetermined or at least a predetermined range, and a general load other than the constant voltage required load. . Specific examples of the constant voltage required load include navigation devices, audio devices, meter devices, and various ECUs such as engine ECUs. In this case, by suppressing the voltage fluctuation of the supplied power, the occurrence of unnecessary reset or the like in each of the above devices is suppressed, and stable operation can be realized. The constant voltage demand load may include a traveling system actuator such as an electric steering device or a brake device. Moreover, as a specific example of a general load, a seat heater, a heater for a rear window defroster, a headlight, a wiper for a front window, a blower fan for an air conditioner, and the like can be mentioned.

  The generator 16 is a generator with a motor function that has a three-phase AC motor and a motor control unit that controls the drive of the motor, and is configured as a mechanical-electrical integrated ISG (Integrated Starter Generator). The generator 16 has a power generation function that generates power (regeneration power) by rotation of an engine output shaft or an axle, and a power running function that applies a rotational force to the engine output shaft. The power running function of the generator 16 applies rotational power to the engine when restarting the automatically stopped engine during idling stop. The generator 16 supplies generated power to the storage batteries 11 and 12 and the electric load 15.

  Next, the electrical configuration of the battery unit U will be described.

  The battery unit U has a first electric path L1 and a second electric path L2 connected in parallel to each other as an in-unit electric path connecting the lead storage battery 11 and the lithium ion storage battery 12. Specifically, the first electric path L1 is an electric path connecting the output terminal P1 and the lithium ion storage battery 12. An output terminal P2 is connected to a connection point N1 which is an intermediate point of the first electric path L1. The generator 16 is connected to the connection point N1 on the first electric path L1.

  A switch configured of a plurality of switches SW1 to SW4 in each of the electric paths L1 and L2 in order to switch the electrical connection state of the generator 16, the storage batteries 11 and 12, and the electric load 15 with each other. A unit SWU is provided. Specifically, in the first electric path L1, the switch SW1 is provided closer to the lead storage battery 11 than the connection point N1. A switch SW2 is provided closer to the lithium ion storage battery 12 than the connection point N1. The electrical path between the first electrical path L1 and the N1-P2 is a large current path on the assumption that the input / output current to the generator 16 flows, and the storage batteries 11, 12 and the generator 16 are connected via this path. Mutual energization is performed.

  One end of the second electric path L2 is connected to the branch point N3 between the output terminal P1 and the switch SW1 on the first electric path L1, and the other end is the switch SW2 and the lithium ion storage battery on the first electric path L1. It is connected to a branch point N4 between T12 and T12.

  An output terminal P3 is connected to a connection point N2 which is an intermediate point of the second electric path L2. In the second electric path L2, the switch SW3 is provided closer to the lead storage battery 11 than the connection point N2. The switch SW4 is provided closer to the lithium ion storage battery 12 than the connection point N2.

  The electric path between the second electric path L2 and the N2-P3 is a small current path on the assumption that a small current flows compared to the first electric path L1 side (that is, the allowable current is smaller than that of the first electric path L1). A small current path is a small current path, and the storage batteries 11 and 12 supply power to the electric load 15 through this path.

  Further, the battery unit U is provided with a bypass path L3 connecting the output terminal P1 and the output terminal P3, and a bypass relay 31 is provided in the bypass path L3. That is, the bypass relay 31 is provided in parallel to the switch SW3. In FIG. 1, a normally closed mechanical relay switch is used as the bypass relay 31.

  The bypass path L3 is a small current path whose allowable current is smaller than that of the first electric path L1, similarly to the second electric path L2.

  In the operating state of the power supply system, the switch SW1 and the switch SW2 are selectively operated in the closed state, whereby at least one of the lead storage battery 11 and the lithium ion storage battery 12 and the generator 16 via the first electric path L1. Power is supplied between the Further, by selectively operating the switch SW3 and the switch SW4 in the closed state, energization between at least one of the lead storage battery 11 and the lithium ion storage battery 12 and the electrical load 15 is performed via the second electrical path L2. To be done.

  On the other hand, when the power supply system is stopped (the ignition switch of the vehicle is off), the switches SW1 to SW4 are off, but the bypass relay 31 is on. In such a situation, the generators 16, the storage batteries 11 and 12, and the various electric loads 15 are electrically disconnected from one another by the switches SW1 to SW4. Meanwhile, the lead storage battery 11 and the electrical load 15 are electrically connected via the bypass relay 31, and dark current is supplied from the lead storage battery 11 to the electrical load 15.

  When the switch SW4 connected in series with the bypass relay 31 is unintentionally brought into conduction when the power supply system is stopped, both the storage batteries 11 and 12 are brought into conduction through the bypass relay 31. At this time, if there is a potential difference between the two storage batteries 11 and 12, an unintended current flows between the two storage batteries 11 and 12.

  When the power supply system is stopped, the opening / closing operation of the switches SW1 to SW4 by the control unit 51 is not performed. Therefore, when an unintended current flows in the second electric path L2 when the system is stopped, there is a risk that overcharging or overcharging may occur in both the storage batteries 11, 12.

  Therefore, in the present embodiment, among the switches SW1 to SW4, the switch SW4 connected in series to the bypass relay 31 is for interrupting the current flowing between the lead storage battery 11 and the lithium ion storage battery 12 via the bypass relay 31. A redundant part is provided.

  Here, the configuration of each of the switches SW1 to SW4 will be specifically described. Each of the switches SW1 to SW4 is configured using a semiconductor switching element such as a MOSFET, and is a switch of a normally open type.

  The switch SW1 includes a switch portion 21 formed of semiconductor switching elements connected in series with the parasitic diodes in opposite directions, and a switch portion 22 formed of semiconductor switching elements in the same direction connected in the parasitic diode directions. , And these switch sections 21 and 22 are connected in parallel. The switches SW2 and SW3 also have the same configuration. That is, the switch SW2 is configured by connecting the switch units 23 and 24 in parallel. The switch SW3 is configured by connecting the switch units 25 and 26 in parallel.

  Each of the switch portions 21 to 26 described above has a pair of semiconductor switching elements in which the directions of the parasitic diodes are opposite to each other. Therefore, when the switches SW1 to SW3 are turned off (opened), that is, when the semiconductor switching elements are turned off, the current flowing through the parasitic diode can also be interrupted.

  The switch SW4 includes switch portions 27a, 27b, 28a, and 28b formed of semiconductor switching elements connected in series in which the directions of parasitic diodes are opposite to each other. Among these, the switch parts 27a and 28a are connected in parallel to constitute a switch SW4a. The switch portions 27b and 28b are connected in parallel to form a switch SW4b. The switch SW4 is configured by connecting the switches SW4a and SW4b in series.

  That is, in the switch unit SWU, the switches SW1 to SW3 are configured using four semiconductor switching elements. On the other hand, the switch SW4 is configured using eight semiconductor switching elements. Therefore, with regard to the switch SW4, even if there is an abnormality in which the switch SW4a becomes conductive, for example, when the system is stopped, the storage battery 11, 12 is electrically disconnected due to the switch SW4b being nonconductive. Can be in the

  That is, one of the switches SW4a and SW4b can open and close the second electric path L2, and from that intention, any one of the switches SW4a and SW4b provides redundancy to the switch SW4. It has become.

  The battery unit U includes a control unit 51 that controls on / off (opening and closing) of the switches SW1 to SW4 and the bypass relay 31. The control unit 51 is configured by a microcomputer including a CPU, a ROM, a RAM, an input / output interface and the like, and is mounted on, for example, the same substrate.

  The control unit 51 operates the switches SW1 to SW4 in the closed state and opens the bypass relay 31 in the system operation state according to the energization request to the electric load 15 and the generator 16. In this case, the control unit 51 outputs an on signal (high signal) as a switch command signal when closing any of the switches SW1 to SW4, and an off signal (low signal) as a switch command signal when opening the switches. Output). The control unit 51 outputs an on signal (high signal) as a relay command signal when opening the bypass relay 31 and outputs an off signal (low signal) as a relay command signal when closing the bypass relay 31.

  An ECU 100 outside the battery unit U is connected to the control unit 51 in the battery unit U. The control unit 51 and the ECU 100 are connected by a communication network such as CAN and can communicate with each other, and various data stored in the control unit 51 and the ECU 100 can be shared with each other. The ECU 100 is an upper control apparatus with respect to the control unit 51, and switches the switches SW1 to SW4 and the bypass relay with respect to the control unit 51 based on the storage state of the storage batteries 11 and 12 and the driving state of the vehicle. Output the command related to the switching control of 31. Thereby, in the present power supply system, charge and discharge are carried out selectively using the lead storage battery 11 and the lithium ion storage battery 12.

  Next, the operation and effect of the configuration of FIG. 1 will be described with reference to FIG. In the following description, it is assumed that there is some abnormality in the current interrupting function of the switch SW4a, and the switch SW4a becomes conductive when the system is stopped. Moreover, it is assumed that the voltage between terminals of the lead storage battery 11 is larger than the voltage between terminals of the lithium ion storage battery 12.

  As shown in FIG. 2, when the system is stopped, the switches SW1 to SW4 are turned off and the bypass relay 31 is turned on. Here, assuming that the switch SW4 is not provided with a redundant portion, and it is assumed that the switch SW4 is configured only by the switch SW4a, as shown by the arrows in the figure, the current A from the lead storage battery 11 to the lithium ion storage battery 12 Will flow. On the other hand, when the system is stopped, this current path can not be cut off, so that the lead storage battery 11 is overdischarged by continuing the discharge of the lead storage battery 11, and the charging of the lithium ion storage battery 12 is continued. There is a risk of overcharging.

  Further, the current A flows in a part of the bypass relay 31 and the second electric path L2 (a range from the connection point N2 to the lithium ion storage battery 12) due to the abnormality of the switch SW4a. The temperature of the substrate rises, and the influence may be exerted on each element on the same substrate.

  On the other hand, according to the configuration of the present embodiment of FIG. 1, even if there is an abnormality in the current interrupting function of the switch SW4a, the current A flowing through a part of the bypass relay 31 and the second electric path L2 is switched It can be shut off by SW4b.

  According to the above, the following excellent effects can be achieved.

  When connecting a normally closed bypass relay 31 electrically connecting the lead storage battery 11 to the electric load 15 in parallel with the switch SW3 of the second electric path L2, each switch SW1 configuring the switch unit SWU when the system is stopped Even when the switch SW4 is turned off, the lead storage battery 11 and the electrical load 15 are electrically connected to each other through the bypass relay 31, so that power can be supplied to the electrical load 15.

  However, in the configuration in which such a bypass relay 31 is provided, when the switch SW4 connected in series with the bypass relay 31 unintentionally becomes conductive, through the bypass relay 31 (switch SW4), The lead storage battery 11 and the lithium ion storage battery 12 are electrically connected. At this time, if there is a potential difference between the lead storage battery 11 and the lithium ion storage battery 12, unintended current flows in both the storage batteries 11, 12.

  When the system is stopped, the states of the switches SW1 to SW4 constituting the switch unit SWU can not be switched. Therefore, if such an unintended current flows, there is a risk that overcharging and overcharging may occur in both storage batteries 11 and 12.

  By the way, since the first electric path L1 is not provided with a normally closed relay (bypass relay) for electrically connecting the lead storage battery 11 and the electric load 15, such an electric relay is compared to the second electric path L2. It is thought that abnormalities do not easily occur.

  Therefore, among the switch SW2 and the switch SW4 provided on the side of the lithium ion storage battery 12, the switch SW4 ensures redundancy for interrupting the current flowing between the lead storage battery 11 and the lithium ion storage battery 12 via the bypass relay 31. It was made to have a redundant part for The switch SW4b is a redundant unit for the switch SW4a. The switch SW4a is a redundant part for the switch SW4b.

  With such a configuration, it is possible to enhance the function of blocking unintended flow of current between the lead storage battery 11 and the lithium ion storage battery 12 via the bypass relay 31 when the system is stopped. Further, among the switch SW2 and the switch SW4 provided on the side of the lithium ion storage battery 12, only the switch SW4 of the second electric path L2 has a redundant part, so both of the switch SW2 and the switch SW4 have redundant parts. The configuration can be simplified as compared to the case where it is provided.

  A redundant portion can be provided in the switch SW4 by connecting in series semiconductor switches that are larger than the switch SW2.

  -When the switches SW1 to SW4 constituting the switch unit SWU are configured using a pair of semiconductor switches and connected in series so that the directions of the parasitic diodes of the pair of semiconductor switches are opposite to each other, By turning off the semiconductor switch, the current component flowing through the diode component specific to the semiconductor switch can also be interrupted.

  However, if any abnormality occurs in the current interrupting function of each of the switches SW1 to SW4, the current can not be completely interrupted even if each of the switches SW1 to SW4 is turned off. Then, in the switch SW4, when such an abnormality occurs, the lead storage battery 11 and the lithium ion storage battery 12 are in a conducting state, and this is compared to the case where the same abnormality occurs in the other switches SW1 to SW3. The influence is considered to be greater.

  Therefore, with regard to the switch SW4, a redundant portion is provided by connecting another semiconductor switch in series to the pair of semiconductor switches. With such a configuration, even if an abnormality occurs in the current interrupting function of the pair of semiconductor switches for the switch SW4, another semiconductor switch connected in series to the pair of semiconductor switches may be connected via the bypass relay 31. Thus, the current flowing between the lead storage battery 11 and the lithium ion storage battery 12 can be cut off. By the above, generation | occurrence | production of the problem which the electric current which is not intended flows between the lead storage battery 11 and the lithium ion storage battery 12 can be suppressed.

  The semiconductor switch provided as the redundant portion in the switch SW4 is configured such that the direction of the parasitic diode in the second electric path L2 is the direction of blocking the current flowing from the lead storage battery 11 to the lithium ion storage battery 12. In this case, of the current flowing between the lead storage battery 11 and the lithium ion storage battery 12, the function of interrupting the current flowing from the lead storage battery 11 to the lithium ion storage battery 12 can be enhanced.

  -The interruption | blocking function of an unintended electric current flowing between the lead storage battery 11 and the lithium ion storage battery 12 can be heightened.

  -When the lithium ion storage battery 12 is configured as a substrate integrated battery unit U housed in the housing case, the bypass relay 31 and the second electric path L2 are caused due to an abnormality in the current interrupting function of the switch SW4. If current A flows to a part of them (a range from the connection point N2 to the lithium ion storage battery 12), the temperature of the substrate in the battery unit U rises, and the influence may be exerted on each element on the same substrate is there. On the other hand, when the above-mentioned redundant portion is provided in the switch SW4, the function of interrupting the current in the second electric path L2 connecting the lead storage battery 11 and the lithium ion storage battery 12 is enhanced, and such an abnormality occurs. Can be suppressed.

  The present invention is not limited to the contents described in the above embodiment, and may be implemented as follows. In the following description, the same components as those described above will be assigned the same reference numerals and detailed descriptions thereof will be omitted. Also, the embodiments can be combined with each other as appropriate, or alternatively selected.

Second Embodiment
The power supply system of 2nd Embodiment is shown in FIG. In FIG. 3, among the switches SW1 to SW4 of the switch unit SWU, the switches SW1 to SW3 have the same configuration as that of FIG. On the other hand, the switch SW4 is configured as follows.

  First, the switch parts 27 and 28 are respectively configured using three semiconductor switching elements S1, S2 and S3. At this time, the two semiconductor switching elements S1 and S2 are connected such that the parasitic diodes are in opposite directions. The direction of the parasitic diode of the remaining one semiconductor switching element S3 is set so as to cut off the current flowing from the lead storage battery 11 to the lithium ion storage battery 12 in the second electric path L2. And it connects in series in semiconductor switching element S1 side among a pair of semiconductor switching elements S1 and S2. In FIG. 3, the semiconductor switching element S3 is provided such that the cathode is on the side of the lead storage battery 11 and the anode is on the side of the lithium ion storage battery 12.

  With such a configuration, it is possible to enhance the effect of interrupting the current flowing from the lead storage battery 11 to the lithium ion storage battery 12 among the currents flowing between both the storage batteries 11 and 12. Therefore, at the time of the stop of the system, it is possible to suppress the occurrence of the inconvenience that the lithium ion storage battery 12 is overcharged by the unintended current.

  Further, in the case of the battery system of the configuration of FIG. 3, a redundant portion is provided in the switch SW4 using a smaller number of semiconductor switches as compared with the battery system of the configuration of FIG. Therefore, the configuration is more advantageous in simplification of the configuration and cost.

(Other embodiments)
In addition to the above-described configurations, a redundant portion can be provided in the switch SW4 by increasing the number of semiconductor switches constituting the switch SW4 more than the number of semiconductor switches constituting the switch SW2. For example, in FIG. 1, the switch SW2 is configured by a series connection of two semiconductor switching elements. In this case, a redundant portion is provided by configuring the switch SW4 by connecting at least three semiconductor switches in series. Also in this case, at least two semiconductor switches of the three semiconductor switches are connected in series so that the directions of the parasitic diodes are opposite to each other. A redundant portion can be provided by serially connecting the remaining semiconductor switches to the series connected body of the pair of semiconductor switches.

  In the above embodiments, when connecting two semiconductor switches in series in each of the switches SW1 to SW4, the anodes of the parasitic diodes are connected to face each other, but the cathodes of the parasitic diodes face each other. It may be connected.

  -In each said embodiment, MOSFET is used as a semiconductor switching element. Besides this, IGBTs, bipolar transistors, etc. can also be used as semiconductor switching elements. In the case of an IGBT or a bipolar transistor, when connecting a pair of semiconductor switching elements in series, the directions of reflux diodes connected in parallel to the respective semiconductor switching elements may be opposite to each other.

  -In the above, the semiconductor switching element provided in the switch SW4 as a redundant part may be provided in the direction to interrupt the current flowing from the lithium ion storage battery 12 to the lead storage battery 11. In this case, the function of interrupting the current flowing from the lithium ion storage battery 12 to the lead storage battery 11 among the currents flowing from both the storage batteries 11 and 12 is enhanced.

  In the above, the bypass relay 31 may be provided outside the battery unit U as long as it is connected in parallel to the switch SW3 and in series to the switch SW4.

  In the above, instead of the bypass relay 31, various types of normally closed switches can be used.

  -In the above, the example which comprised each switch SW1-SW4 with which switch unit SWU is comprised with a semiconductor switch was shown. Besides these, these switches SW1 to SW4 can also be configured using mechanical switches. Also in this case, by increasing the number of switch elements constituting the switch SW4 out of the switches SW2 and SW4 provided on the lithium ion storage battery 12 side, it is possible to provide a redundant portion in the switch SW4.

  11: Lead storage battery, 12: lithium ion storage battery, 15: electric load, 16: rotating electric machine, 31: bypass relay, L1: first electric path, L2: second electric path, S3: semiconductor switching element, SW1: switch, SW2 ... switch, SW3 ... switch, SW4 ... switch, SW4a ... switch, SW4b ... switch, SWU ... switch unit.

Claims (5)

A first storage battery (11) and a second storage battery (12) respectively connected in parallel to the generator (16) and the electric load (15);
An electrical path connecting the first storage battery and the second storage battery, a first electrical path (L1) and a second electrical path (L2) connected in parallel with each other,
A switch unit (SWU) provided on the first electrical path and the second electrical path to switch the electrical connection between the generator, the storage batteries, and the electrical load;
A normally closed relay (31) electrically connecting the first storage battery and the electrical load;
The switch unit is
A first switch (SW1) provided closer to the first storage battery than a first connection point with the generator in a portion parallel to the second electrical path of the first electrical path;
A second switch (SW2) provided closer to the second storage battery than the first connection point in a portion parallel to the second electrical path of the first electrical path;
A third switch (SW3) provided closer to the first storage battery than a second connection point (N2) with the electric load in a portion parallel to the first electric path in the second electric path;
And a fourth switch (SW4) provided closer to the second storage battery than the second connection point in a portion parallel to the first electrical path in the second electrical path,
The relay is connected in parallel to the third switch, and connected in series to the fourth switch,
Among the second switch and the fourth switch provided on the side of the second storage battery, the fourth switch is a redundancy that cuts off the current flowing between the first storage battery and the second storage battery via the relay. Power supply system characterized by having a redundant part (SW4a, SW4b, S3) for securing the power. Each of the switches is configured using a semiconductor switch,
2. The power supply system according to claim 1, wherein the redundant portion is provided by connecting in series the semiconductor switches whose number is larger than that of the second switch in the fourth switch. Each of the switches is configured using a pair of semiconductor switches, and the pair of semiconductor switches are connected in series so that the directions of the parasitic diodes are opposite to each other.
3. The semiconductor device according to claim 1, wherein the redundant portion is provided by connecting in series another semiconductor switch to the pair of semiconductor switches on the second electric path side with respect to the connection point. Power system.   The power supply system according to claim 3, wherein the semiconductor switch provided as the redundant portion is provided in a direction in which a direction of the parasitic diode cuts off a current flowing from the first storage battery to the second storage battery in the second electric path. .   The power supply system according to any one of claims 1 to 4, wherein the first storage battery is a lead storage battery, and the second storage battery is a lithium ion storage battery.

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