WO2018116741A1

WO2018116741A1 - Power supply system

Info

Publication number: WO2018116741A1
Application number: PCT/JP2017/042122
Authority: WO
Inventors: 祐樹前田; 大和宇都宮
Original assignee: 株式会社デンソー
Priority date: 2016-12-20
Filing date: 2017-11-23
Publication date: 2018-06-28
Also published as: JP2018102048A; JP6662282B2

Abstract

The power supply system is provided with: a voltage source (11, 12, 13, 17); electrical loads (16, 17) to which electric power is supplied from the voltage source; switch parts (21 through 24) for opening and closing electric paths (L1 through L4) connecting the voltage source to the electrical loads; a control unit (50) for outputting an open command and a close command to control the open switch parts; and current detection parts (41 through 44) for detecting currents flowing into the switch parts. The control unit receives detection signals from the current detection parts as input, determines whether or not an overcurrent is flowing in the switch parts on the basis of the detection signals when electric power is being supplied to the electrical loads, and outputs the open command on the basis of the determination to open the switch parts. The detection signals are input to the power supply system. The power supply system is provided with: a comparison circuit for comparing the detection signals with an overcurrent determination value and outputting an overcurrent signal on the basis of the comparison result; and a cutoff circuit unit (70) for opening the switch parts independently of the open command if the overcurrent signal is input thereto and cutting off the overcurrent.

Description

Power system

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2016-246539 filed on December 20, 2016, the contents of which are incorporated herein by reference.

This disclosure relates to a power supply system applied to a vehicle or the like.

Conventionally, in a power supply system including a storage battery and an electric load, various techniques for optimizing charge / discharge control in the storage battery have been proposed. For example, Patent Document 1 describes a power supply system including a first storage battery and a second storage battery that are connected in parallel to an electric load. In this power supply system, a switch is provided in each energization path that connects the electrical load to the first storage battery and the second storage battery, and charging / discharging of each storage battery is controlled by opening and closing each switch. Specifically, opening / closing control of each switch is performed by a control unit (microcomputer) based on the charging state of each rechargeable battery.

JP2012-130108A

By the way, in the above power supply system, when an overcurrent occurs, a shut-off process is performed as a fail-safe process by the control unit. For example, when a ground fault occurs in the electric load during power supply from the storage battery to the electric load, an overcurrent flows through the electrically conducting path. In such a case, the control unit determines that the overcurrent is flowing based on the detection signal output from the current detection unit, and opens the switch of the energization path through which the overcurrent flows, thereby overcurrent. Is shut off. However, in this case, when the fail-safe process is performed by the control unit, a determination process that the overcurrent generation state continues for a predetermined time is performed, which may cause a delay in opening the switch. In such a case, the overcurrent will flow in the power supply system for a longer time, which may cause inconvenience.

The present disclosure has been made in view of the above circumstances, and a main purpose thereof is to provide a power supply system that can quickly protect the power supply system when an overcurrent occurs.

In the first means,
A voltage source; an electric load supplied with electric power from the voltage source; an electric path connecting the voltage source and the electric load; an opening / closing part for opening or closing the electric path; and the opening / closing part A control unit that outputs an opening command to open and a closing command to close the opening and closing unit to control opening and closing of the opening and closing unit, and a current detection unit that detects a current flowing through the opening and closing unit,
The control unit receives a detection signal from the current detection unit, and overloads the switching unit based on the detection signal when the power is supplied from the voltage source to the electrical load through the switching unit. A power supply system that outputs the opening command based on the determination and opens the opening and closing unit,
A comparison circuit unit that receives a detection signal of the current detection unit, compares the detection signal with a predetermined overcurrent determination value, and outputs an overcurrent signal indicating the occurrence of overcurrent based on the comparison result When,
When the overcurrent signal is input, the open / close unit is opened independently of the open command output from the control unit, and a cutoff circuit unit that cuts off the overcurrent,
Is provided.

In the power supply system, power is supplied from the voltage source to the electric load by closing the open / close section provided in the electric path. During this power supply, an overcurrent may flow in the electrical path due to a ground fault or the like occurring in the electrical load. In such a case, the control unit determines that an overcurrent flows through the open / close unit based on the detection signal, and outputs the open command to open the open / close unit. However, in this case, in the shut-off process in the control unit, it is considered that it takes time until the switch is actually opened after an overcurrent occurs, resulting in inconvenience in the power supply system.

In this regard, in the above configuration, an overcurrent flows through the switching unit based on a detection signal input from the current detection unit using a comparison circuit unit or a shielding circuit unit (electric circuit) provided separately from the control unit. An overcurrent signal indicating the effect is output, and accordingly, the opening / closing part is opened independently of the opening command from the control part. That is, in this case, the overcurrent can be quickly cut off by detecting the overcurrent and opening the opening / closing unit by using a circuit unit of a different system different from the cut-off process by the control unit. Thereby, when an overcurrent occurs, the power supply system can be protected quickly.

The second means includes a drive circuit that inputs the opening command and the closing command from the control unit, and that opens and closes the opening / closing unit based on these commands, and the interruption circuit unit includes the overcurrent signal. Is input, the opening / closing part is opened by invalidating the closing drive signal output from the driving circuit to the opening / closing part.

According to the above configuration, even if a closing command is continuously output from the control unit after the occurrence of an overcurrent, the shut-off circuit unit invalidates the closing drive signal from the drive circuit, and accordingly the opening / closing unit is It is forcibly released. Therefore, it is possible to open the opening / closing unit without operating the opening / closing command of the control unit, and as a result, it is possible to respond quickly when an overcurrent occurs.

In the third means, a bypass switch that bypasses the open / close unit and connects the voltage source and the electric load is provided, and a bypass switch that opens or closes the bypass route, and the control unit issues the open command. A bypass circuit unit that closes the bypass switch based on the output, and the control unit determines that an overcurrent flows through the opening / closing unit based on the detection signal. And the opening / closing part is opened after the bypass switch is switched from the open state to the closed state, and when the overcurrent signal is input, the cutoff circuit part The opening / closing part is opened before switching from the open state to the closed state.

In the above power supply system, the bypass switch is closed when the opening / closing part is opened so that electric power can be always supplied to the electric load via the electric path or the bypass path. Furthermore, in order to prevent the supply of electric power to the electric load from being interrupted, an opening / closing part opening command is output, and the opening / closing part is opened after the bypass switch is switched from the open state to the closed state. However, in this case, the opening / closing part cannot be opened until the bypass switch is closed even in the interruption process associated with the occurrence of overcurrent. Therefore, there is a further concern about the influence of overcurrent.

In this regard, in the above configuration, when the overcurrent signal is input, the cutoff circuit unit opens the opening / closing unit before the bypass switch is switched from the open state to the closed state, so that the bypass switch is closed. The opening / closing part can be opened without waiting. Thereby, when an overcurrent occurs, the opening / closing part can be opened more quickly, and the power supply system can be suitably protected.

In the fourth means, the control section does not output the opening command of the opening / closing section when the opening / closing section is opened by the interrupting circuit section based on the overcurrent signal.

In the above power supply system, when an overcurrent occurs, the opening / closing part is opened by the cutoff circuit part earlier than the cutoff process by the control part. In this case, the bypass switch is opened when the opening / closing part is opened. However, after that, when the opening / closing unit opening command is output by the blocking process by the control unit, the bypass switch is closed. In such a case, although the overcurrent is once interrupted, it is considered that the overcurrent flows again to the power supply system, resulting in inconvenience.

In this configuration, when the opening / closing unit is opened based on the overcurrent signal, the control unit does not output the opening / closing unit opening command, so that the bypass switch is closed along with the opening / closing unit opening command. Can be avoided. Thereby, it is possible to prevent an overcurrent from unintentionally flowing to another path of the power supply system.

In the fifth means, the bypass switch is a mechanical relay.

In the case of mechanical relays, it takes time to open and close the contacts, and more time is required to switch the switch than a semiconductor switch. For this reason, when the bypass switch is a mechanical relay, there is a greater concern about the influence of overcurrent in the interruption process by the control unit. In this respect, in the above configuration, when an overcurrent occurs, the opening / closing part can be opened without waiting for the bypass switch of the mechanical relay to be closed, thereby further reducing the time until the opening part is opened. Can do.

In the sixth means, as the voltage source, a first storage battery and a second storage battery connected in parallel to each other are provided, and a current path between the first storage battery and the second storage battery is provided in series as the open / close section. 1 opening and closing part and 2nd opening and closing part, the 1st current detection part and the 2nd current detection part which detect the current which flows through each said opening and closing part, and the middle point between these 1st opening and closing part and the 2nd opening and closing part An electrical load is connected to the control unit, the control unit outputs the close command and the open command to the open / close units, respectively, to control the open / close of the open / close units, and the bypass path includes the first open / close unit. The bypass circuit unit is connected to the voltage source and the electrical load, and the bypass circuit unit is based on the opening command being output from the control unit to both of the switching units. Close the bypass switch. To.

According to the above configuration, even in a two-power supply system, the power supply system can be quickly shut down when an overcurrent occurs, and thus the power supply system can be properly protected.

In the seventh means, the detection signal input to the control unit is subjected to a first smoothing process that suppresses a change in the detection value of the current detection unit, and is input to the comparison circuit unit. The detection signal is obtained by performing a second smoothing process that suppresses a change in the detection value of the current detection unit, and the second smoothing process is smoother than the first smoothing process. The degree is set to be small.

In the annealing process for the detection value of the current detection unit, the smaller the degree of annealing, the better the response than when it is larger. In consideration of this point, the second smoothing process is set so that the degree of smoothing is smaller than that of the first smoothing process. Therefore, the detection signal input to the comparison circuit unit is sent to the control unit. The response is better than the input detection signal. Thereby, the comparison circuit unit can detect the overcurrent more quickly.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is an electric circuit diagram showing the power supply system of the first embodiment. FIG. 2 is a diagram for explaining opening and closing of a switch by a microcomputer. FIG. 3 is a diagram showing power supply from the storage battery to the electric load. FIG. 4 is a diagram showing a shut-off process when an overcurrent occurs in a conventional power supply system, FIG. 5 is a time chart of the interruption process when an overcurrent occurs in the conventional power supply system, FIG. 6 is a diagram illustrating forced interruption when an overcurrent occurs in the first embodiment. FIG. 7 is a flowchart showing processing in the microcomputer. FIG. 8 is a time chart of forced cutoff at the occurrence of overcurrent in the first embodiment. FIG. 9 is an electric circuit diagram showing the power supply system of the second embodiment.

(First embodiment)
Hereinafter, an embodiment embodying the present disclosure will be described with reference to the drawings. In the present embodiment, an in-vehicle power supply system that supplies power to various devices of the vehicle in a vehicle that runs using an engine (internal combustion engine) as a drive source is embodied.

As shown in FIG. 1, this power supply system is a dual power supply system having a lead storage battery 11 and a lithium ion storage battery 12 as a first storage battery and a second storage battery. Each storage battery 11 and 12 can be charged by an alternator 13 as a generator, and each storage battery 11 and 12 can supply power to a starter 14 and various

electric loads

15 and 16. It has become. In this system, the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the alternator 13, and the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the

electrical loads

15 and 16. In the present embodiment, each of the storage batteries 11 and 12 and the alternator 13 corresponds to a “voltage source”.

The lead storage battery 11 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 12 is a high-density storage battery that has less power loss during charging / discharging than the lead storage battery 11, and has a high output density and energy density. The lithium ion storage battery 12 may be a storage battery having higher energy efficiency during charging / discharging than the lead storage battery 11. Moreover, the lithium ion storage battery 12 is comprised as an assembled battery which has a some single cell, respectively. These storage batteries 11 and 12 have the same rated voltage, for example, 12V.

Although the detailed description by illustration is omitted, the lithium ion storage battery 12 is housed in a housing case and configured as a battery unit U integrated with a substrate. The battery unit U has output terminals T1, T2, and T0, of which the lead storage battery 11, the alternator 13, the starter 14, and the electric load 15 are connected to the output terminals T1 and T0, and the electric load is connected to the output terminal T2. 16 is connected.

The rotating shaft of the alternator 13 is connected to an engine output shaft (not shown) by a belt or the like, and the rotating shaft of the alternator 13 is rotated by the rotation of the engine output shaft. That is, the alternator 13 generates power (regenerative power generation) by rotating the engine output shaft and the axle.

The electric loads 15 and 16 have different requirements for the voltage of the supplied power supplied from the storage batteries 11 and 12. Among these, the electric load 16 includes a constant voltage required load that is required to be stable so that the voltage of the supplied power fluctuates within a predetermined range or at least within a predetermined range. On the other hand, the electric load 15 is a general electric load other than the constant voltage required load. It can be said that the electric load 16 is a protected load. In addition, it can be said that the electric load 16 is a load that does not allow a power supply failure, and the electric load 15 is a load that allows a power supply failure compared to the electric load 16.

Specific examples of the electrical load 16 that is a constant voltage required load include various ECUs such as a navigation device, an audio device, a meter device, and an engine ECU. In this case, by suppressing the voltage fluctuation of the supplied power, it is possible to suppress an unnecessary reset or the like in each of the above devices, and to realize a stable operation. As the electric load 16, a traveling system actuator such as an electric steering device or a brake device may be included. Specific examples of the electric load 15 include a seat heater, a heater for a defroster for a rear window, a headlight, a wiper for a front window, and a blower fan for an air conditioner.

Next, the electrical configuration of the battery unit U will be described. As shown in FIG. 1, the battery unit U has an energization path L1 that connects the output terminals T1 and T2 and an energization path that connects a connection point N1 on the energization path L1 and the lithium ion storage battery 12 as an in-unit electrical path. L2 is provided. Among these, the 1st switch 21 is provided in the electricity supply path | route L1, and the 2nd switch 22 is provided in the electricity supply path | route L2. In addition, if it says by the electrical path which connects the lead storage battery 11 and the lithium ion storage battery 12, the 1st switch 21 will be provided in the lead storage battery 11 side rather than the connection point N1, and the lithium ion storage battery 12 side from the connection point N1. The second switch 22 is provided.

Each of these

switches

21 and 22 includes, for example, 2 × n MOSFETs (semiconductor switching elements), and the parasitic diodes of the two sets of MOSFETs are connected in series so as to be opposite to each other. By this parasitic diode, when each

switch

21 and 22 is turned off, the current flowing through the path in which the switch is provided is completely cut off. Note that IGBTs, bipolar transistors, or the like can be used as the

switches

21 and 22 instead of MOSFETs. In the case where IGBTs or bipolar transistors are used as the

switches

21 and 22, reverse diodes may be connected in parallel to the

switches

21 and 22, respectively, instead of the parasitic diode.

The battery unit U is provided with a bypass path L0 that bypasses the first switch 21. The bypass path L0 is provided in parallel to the energization path L1 so as to connect the output terminal T0 and the connection point N1 on the energization path L1. That is, the lead storage battery 11 and the electrical load 16 can be connected by the bypass path L0 without going through the first switch 21. On the bypass path L0, a fuse 30 and a bypass switch 31 composed of a normally closed mechanical relay are provided in series. The fuse 30 is provided closer to the lead storage battery 11 than the bypass switch 31, that is, between the bypass switch 31 and the output terminal T0.

With this configuration, the lead storage battery 11 and the electrical load 16 are electrically connected even when the first switch 21 is turned off (opened) by closing the bypass switch 31. For example, dark current is supplied to the electric load 16 via the bypass switch 31 in a state where the power switch (ignition switch) of the vehicle is turned off. Note that the bypass path L0, the fuse 30 and the bypass switch 31 may be provided outside the battery unit U.

The battery unit U includes each of the

switches

21 and 22 and a microcomputer 50 (control unit) that controls on / off (opening / closing) of the bypass switch 31. The microcomputer 50 includes a CPU, a ROM, a RAM, an input / output interface, and the like. An ECU 100 outside the battery unit U is connected to the microcomputer 50. That is, the microcomputer 50 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 microcomputer 50 and the ECU 100 can be shared with each other.

The microcomputer 50 controls on / off of the

switches

21 and 22 and the bypass switch 31 based on the storage state of each of the storage batteries 11 and 12 and a command signal from the ECU 100 that is the host controller. Specifically, the microcomputer 50 controls opening and closing by outputting an opening command for opening the

switches

21 and 22 and a closing command for closing the

switches

21 and 22. Here, in terms of closing the switch, the microcomputer 50 outputs a close (ON) command to the drive circuit 52. Then, the drive circuit 52 outputs the gate signal of the corresponding switch, that is, the closing drive signal. Specifically, the corresponding switch is closed (turned on) by outputting the gate voltage boosted to 10 V, for example. Although FIG. 1 shows the open / close control for the second switch 22, the same applies to the first switch 21.

Thus, charging / discharging is performed by selectively using the lead storage battery 11 and the lithium ion storage battery 12 by the on / off control of the switch of the microcomputer 50. Further, the microcomputer 50 controls the electric load 16 (unprotected load) so that electric power is always supplied from each of the storage batteries 11 and 12. Therefore, when both the first switch 21 and the second switch 22 are in an open (off) state, the bypass switch 31 is closed.

Here, opening and closing of the switch will be described with reference to FIG. The microcomputer 50 outputs an open command or a close command to the drive circuit 52 of each

switch

21, 22 in order to open or close each

switch

21, 22. The

switches

21 and 22 are opened and closed by outputting a gate signal from the drive circuit 52 based on the open command or the close command. On the other hand, the opening / closing command of each switch output from the microcomputer 50 is also input to the NOR circuit C 1 that controls the opening / closing of the bypass switch 31. Specifically, an opening / closing command for the first switch 21 and an opening / closing command for the second switch 22 are input to the NOR circuit C1. If the signal output from the NOR circuit C1 is “1”, the bypass switch 31 is closed, and if it is “0”, the bypass switch 31 is opened.

In FIG. 2, “0” is input to the NOR circuit C1 when the commands of the

switches

21 and 22 are open commands, and “1” is input when the commands are close commands. Therefore, when the close command is output to at least one of the

switches

21 and 22, the bypass switch 31 is opened, and when the open command is output to both the

switches

21 and 22, the bypass switch 31 is open. Is closed. As described above, when the

switches

21 and 22 are opened (off) and the bypass switch 31 is closed (on), the first switch 21 and the first switch 21 are connected from the microcomputer 50 so that the power supply to the electric load 16 is not interrupted. The bypass switch 31 is closed based on the output of an open (off) command to both the two switches 22.

Furthermore, in this power supply system, in order to prevent the supply of power to the electric load 16 from being interrupted, the bypass switch 31 is released from the open state in response to the output of an open (off) command to both the

switches

21 and 22. After switching to the closed state, the

switches

21 and 22 are opened. That is, in this case, there is a delay from when the switch opening command is output until the switch is actually opened, and the drive circuit 52 is provided with a delay circuit (not shown). As a result, the closed state of the first switch 21 or the second switch 22 and the closed state of the bypass switch 31 overlap to prevent the power supply to the electrical load 16 from being interrupted.

The battery unit U includes a first current detection unit 41 that detects a current flowing through the first switch 21 and a second current detection unit 42 that detects a current flowing through the second switch 22. Specifically, the first current detection unit 41 is provided on the energization path L1, and the second current detection unit 42 is provided on the energization path L2. Note that the first current detection unit 41 may be provided between, for example, a pair of MOSFETs in the first switch 21. In this case, the first current detector 41 detects a current flowing between the MOSFETs. Similarly, the second current detection unit 42 may be provided for the second switch 22.

In the power supply system configured as described above, power can be supplied from at least one of the lead storage battery 11 and the lithium ion storage battery 12 to the electric load 16. FIG. 3 shows a case where power is supplied from the lithium ion storage battery 12 to the electric load 16, for example. In this case, the microcomputer 50 issues an off command to the first switch 21 so that the first switch 21 is in an open (off) state, and an on command is issued to the second switch 22. Thus, the second switch 22 is in a closed (on) state.

By the way, when a ground fault occurs at the electric load 16 when power is supplied to the electric load 16, for example, an overcurrent flows through the electrically conductive path. In the case of FIG. 3, overcurrent flows from the lithium ion storage battery 12 to the electric load 16 via the second switch 22, and the resistance of the switch and the electric path becomes a problem. When such an overcurrent abnormality occurs, fail safe processing (cut-off processing) by the microcomputer 50 is performed in the conventional power supply system. Such fail-safe processing will be described below.

In FIG. 1, first, a detection value (current value) output from the second current detection unit 42 is input as a detection signal to the microcomputer 50 via the first filter 51a. The first filter 51a is a low-pass filter, and here, a first smoothing process is performed to suppress a change in the detected value. Then, the microcomputer 50 determines that an overcurrent is flowing based on the input detection signal. Specifically, it is determined that an overcurrent flows when a state where the input current value (detection signal) is larger than the threshold value Th1 continues for a predetermined time. When the microcomputer 50 determines that an overcurrent is flowing, the microcomputer 50 outputs an open (off) command for the second switch 22 to the drive circuit 52.

Then, the bypass switch 31 is closed based on the output of the second switch 22 off command from the microcomputer 50 (FIG. 4). In this case, when the grounded electrical load 16 and the lead storage battery 11 are conducted, an overcurrent flows through the bypass path L0, and the fuse 30 is blown. As a result, the bypass path L0 is blocked. Further, the second switch 22 is opened (turned off) by closing the bypass switch 31 in a situation where an off command for the second switch 22 is output. Thereby, an overcurrent is interrupted in the power supply system.

Such fail-safe processing by the microcomputer 50 will be described with reference to the timing chart of FIG. In FIG. 5, it is assumed that a ground fault has occurred in the electric load 16 when power is supplied from the lithium ion storage battery 12 to the electric load 16. At the start of the timing chart, the first switch 21 is in the open state, The switch 22 is in a closed state. The current value of the second switch 22 in the figure indicates a value based on the detection signal input to the microcomputer 50. That is, the current value after the first annealing process is shown.

When a ground fault occurs at the electric load 16 at the timing t1, the current flowing through the second switch 22 increases. When the threshold Th1 is exceeded at the timing t2, it is determined whether or not an overcurrent is flowing. Specifically, it is determined that an overcurrent flows when a period in which the current value exceeds the threshold Th1 exceeds a predetermined time.

When it is determined that an overcurrent flows through the second switch 22 at timing t3, an open (off) command for the second switch 22 is output. At this time, energization of the relay coil is turned off as an opening command is output to both the first switch 21 and the second switch 22. Then, the bypass switch 31 is closed at timing t4. Thereafter, the second switch 22 is opened (off) due to the bypass switch 31 being closed. Specifically, it is detected that a current has flowed through the bypass path L0 as the bypass switch 31 is closed, and based on this, the second switch 22 is opened (timing t5).

In FIG. 5, in the fail safe process by the microcomputer 50, it takes time (several hundred ms) from timing t1 to t5 until the second switch 22 is opened after the ground fault occurs in the electric load 16. Specifically, the time from timing t1 to t5 is specifically the time from the occurrence of the ground fault to the time when the threshold Th1 is exceeded (timing t1 to t2), the time required to determine overcurrent (timing t2 to t3), the bypass switch 31 The connection time (timing t3 to t4) corresponds to the opening time of the second switch 22 (timing t4 to t5).

As described above, in the fail-safe process in the microcomputer 50, it is considered that there is a problem in the power supply system due to the time from when the overcurrent occurs until the power supply system is actually shut down. Furthermore, depending on the calculation load in the microcomputer 50, a delay may occur in the fail safe process itself such as overcurrent determination.

Therefore, in the power supply system according to the present embodiment, the detection signal of each of the

current detection units

41 and 42 is compared with a predetermined overcurrent determination value, and an overcurrent signal indicating the occurrence of overcurrent is based on the comparison result. And a shutoff circuit unit 70 that shuts off the overcurrent by opening the

switches

21 and 22 independently of the open command output from the microcomputer 50 when an overcurrent signal is input. And so on. That is, by using hardware configured by an electric circuit, the

switches

21 and 22 are opened independently of the fail-safe process by the microcomputer 50, and the power supply system is forcibly cut off.

Explain the forced shutdown by the above hardware. The currents flowing through the

switches

21 and 22 are detected by shunt resistors as the

current detectors

41 and 42, and are input to the

filters

51a and 51b via amplifiers. The detection values (current values) of the

current detection units

41 and 42 are input as detection signals to the comparison circuit unit 60 via the second filter 51b. The second filter 51b is a low-pass filter, and here, a second smoothing process is performed to suppress a change in the detected value. In the present embodiment, the degree of smoothing of the second smoothing process is set to be smaller than the degree of smoothing of the first smoothing process. That is, the detection signal (current value Ib) output from the second filter 51b has better responsiveness than the detection signal (current value Ia) output from the first filter 51a.

The comparison circuit unit 60 includes a comparator 61 and a latch circuit 62. In the comparator 61, the current value Ib that has been subjected to the second smoothing process is compared with the threshold value Th2. The threshold value Th <b> 2 is provided as an overcurrent determination value that can determine that an overcurrent is flowing, and is a value that takes into account the variation of the current detection unit in the normal current use region. Here, the threshold Th2 is set to several hundred A. In the present embodiment, the threshold value Th2 and the threshold value Th1 are the same value, but may be different values. For example, the threshold value Th2 may be a value greater than the threshold value Th1, and the threshold value Th2 may be a value smaller than the threshold value Th1. The comparator 61 outputs a high-state signal, that is, an overcurrent signal to the latch circuit 62 when the input current value Ib exceeds the threshold Th2.

The latch circuit 62 is configured by using, for example, a flip-flop circuit, and can hold a signal output from the comparator 61. Therefore, while the signal output from the comparator 61 is a high state signal, the high state signal is held. That is, when an overcurrent is detected, an overcurrent signal is output from the comparison circuit unit 60.

The overcurrent signal output from the comparison circuit unit 60 is input to the interruption circuit unit 70. The cutoff circuit unit 70 includes a cutoff circuit 71 and a bipolar transistor 72. The cutoff circuit 71 outputs the base signal of the bipolar transistor 72 based on the overcurrent signal. As a result, the bipolar transistor 72 is closed (turned on). The collector side of the bipolar transistor 72 is connected to the signal path of the gate signals of the

switches

21 and 22 output from the drive circuit 52. On the other hand, the emitter side is connected to the ground. Therefore, when an overcurrent signal is input to the cutoff circuit unit 70, the bipolar transistor 72 is turned on, and the voltage based on the closing drive signals of the

switches

21 and 22 falls to the ground level. That is, the close (on) command of each

switch

21 and 22 is forcibly invalidated (stopped). Thereby, each

switch

21 and 22 is opened, and an overcurrent is interrupted | blocked. In place of the bipolar transistor 72, an IGBT, a MOSFET, or the like can be used.

Further, the overcurrent signal output from the latch circuit 62 is reset by a reset signal from the microcomputer 50.

FIG. 6 shows an outline of forced cutoff in this embodiment. In FIG. 6, when a ground fault occurs in the electric load 16 when power is supplied from the lithium ion storage battery 12 to the electric load 16, the on-command of the second switch 22 output from the microcomputer 50 is stopped by the cutoff circuit unit 70. Thus, the second switch 22 is forcibly opened (off). That is, in this case, before the switching from the on command to the off command is performed by the fail safe process of the microcomputer 50, the second switch 22 is opened by the cutoff circuit unit 70. Therefore, the second switch 22 is opened while the bypass switch 31 is opened. Thereby, it is avoided that the fuse 30 is blown.

Although FIG. 6 shows the case where the second switch 22 is forcibly opened (turned off), the same applies to the first switch 21. That is, when a ground fault occurs in the electrical load 16 during power feeding from the lead storage battery 11 to the electrical load 16, the cutoff circuit unit 70 stops the ON command for the first switch 21 output from the microcomputer 50. The first switch 21 is forcibly opened (off).

On the other hand, in this embodiment, fail-safe processing by the microcomputer 50 is also performed in parallel with the forced cutoff by hardware. Here, processing executed by the microcomputer 50 will be described with reference to a flowchart of FIG. The process according to the flowchart of FIG. 7 is repeatedly executed at predetermined intervals.

First, in step S11, it is determined whether or not the ignition switch is on. If step S11 is YES, the process proceeds to step S12. If step S11 is NO, the process is terminated.

In step S12, it is determined whether or not a command to turn off the first switch 21 (open command) is output. In step S13, a command to open the second switch 22 (open command) is output. Determine whether or not. Here, in this power supply system, when the ignition switch is on, in principle, both the

switches

21 and 22 are not turned off, and at least one of them is turned on. Therefore, step S12 being YES means that the first switch 21 is in an off state and the second switch 22 is in an on state, and that step S13 is YES that the first switch 21 is in an on state, The second switch 22 is in an off state, and NO in step S13 means that the first switch 21 and the second switch 22 are in an on state.

That is, when step S12 is affirmed, power is being supplied from the lithium ion storage battery 12 to the electrical load 16, and when step S13 is affirmed, power is supplied from the lead storage battery 11 to the electrical load 16. When step S13 is negative, power is being supplied from the lead storage battery 11 and the lithium ion storage battery 12 to the electrical load 16.

In step S14, it is determined whether or not an overcurrent is detected. Specifically, it is determined whether or not the current value Ia detected by the second current detection unit 42 and input to the microcomputer 50 exceeds the threshold Th1 and continues for a predetermined time. If step S14 is YES, the command which turns off the 2nd switch 22 as a fail safe process is output (step S15). In subsequent step S16, the bypass switch 31 is closed.

In step S17, it is determined whether or not an overcurrent is detected. Specifically, it is determined whether or not the current value Ia detected by the first current detector 41 and input to the microcomputer 50 exceeds the threshold value Th1 and has continued for a predetermined time. If step S17 is YES, the command which turns off the 1st switch 21 as a fail safe process is output (step S18). In subsequent step S16, the bypass switch 31 is closed.

In step S19, it is determined whether or not an overcurrent is detected. Specifically, it is determined whether or not each current value Ia detected by each

current detection unit

41 and 42 and input to the microcomputer 50 exceeds the threshold Th1 and continues for a predetermined time. If step S19 is YES, that is, if at least one of the current values Ia exceeds the threshold Th1 and continues for a predetermined time, a command to turn off the first switch 21 and the second switch 22 as a fail-safe process is issued. Output (step S20). In subsequent step S15, the bypass switch 31 is closed.

On the other hand, if Steps S14, S17, and S19 are NO, this processing is terminated as it is. In the present embodiment, the overcurrent is detected by the comparison circuit unit 60 under the circumstances in which these steps S14, S17, and S19 are denied, that is, before the microcomputer 50 determines that the overcurrent is flowing. Then, the

switches

21 and 22 are opened by the cutoff circuit unit 70.

Here, after the overcurrent is cut off by the forced cut-off in the present embodiment, when a switch-off command is output as the fail-safe process (cut-off process) of the microcomputer 50, the bypass switch 31 is closed. . In this case, although the overcurrent is once interrupted, the overcurrent flows again through the power supply system, which is considered to cause inconvenience. For example, an overcurrent flows through the bypass path L0, and the fuse 30 is blown.

Therefore, in the present embodiment, after the

switches

21 and 22 are opened by the cutoff circuit unit 70, the bypass switch 31 is not closed. Specifically, the microcomputer 50 does not output an OFF command for the

switches

21 and 22 as fail-safe processing. More specifically, the latch circuit 62 outputs a signal indicating that the

switches

21 and 22 are forcibly opened to the microcomputer 50, and the microcomputer 50 continues to turn on the corresponding switch based on the signal. That is, the bypass switch 31 is prevented from being closed by preventing the off command from being output to both the

switches

21 and 22.

Subsequently, the forced cutoff in the present embodiment will be described using the timing chart of FIG. In FIG. 8, as in FIG. 5, it is assumed that a ground fault has occurred in the electric load 16 when power is supplied from the lithium ion storage battery 12 to the electric load 16. At the start of the timing chart, the first switch 21 is In the off state, the second switch 22 is in the on state. Note that the solid line of the current value of the second switch 22 in the figure indicates the value Ib based on the detection signal input to the comparison circuit unit 60. That is, the current value obtained by performing the second annealing process is shown. On the other hand, the alternate long and short dash line indicates the value Ia based on the detection signal input to the microcomputer 50 shown in FIG.

When a ground fault occurs at the electric load 16 at the timing t11, the current flowing through the second switch 22 increases. When the current value Ib exceeds the threshold Th2 at the timing t12, the output signal of the comparator 61 of the comparison circuit unit 60 is high. It becomes a state and is immediately output to the cutoff circuit unit 70 as an overcurrent signal.

Then, based on the overcurrent signal, the shutoff circuit unit 70 stops the second switch 22 closing (on) command at the timing t3, so that the second switch 22 is opened (off). Thereby, an overcurrent is interrupted and the power supply system is protected.

At this time, a signal indicating that the second switch 22 has been opened is input to the microcomputer 50, whereby the close (on) command for the second switch 22 is maintained. That is, the timing t13 is earlier than the timing t14 at which the microcomputer 50 determines that an overcurrent is flowing. Then, by keeping the second switch 22 closed (ON) command, the bypass switch 31 is kept open.

In FIG. 8, in the forced cutoff in the present embodiment, the time from when the ground fault occurs in the electrical load 16 until the second switch 22 is opened is the time (several hundred μs) from timing t11 to t13. Compared with the time 5 (several hundred ms) of the timing t1 to t5 of FIG. Specifically, by performing forced interruption using an electric circuit provided separately from the microcomputer 50, the overcurrent determination time (timing t2 to t3) in the microcomputer 50 and the connection time (timing of the bypass switch 31) Since t3 to t4) can be omitted, the time until the second switch 22 is opened can be suitably shortened. Further, since the detection signal (current value Ib) input to the comparison circuit unit 60 passes through the second filter 51b, the time from the occurrence of the ground fault to exceeding the threshold value Th1 (timing t11 to t12) is also shown in FIG. 5 is shorter than the timing t1 to t2.

As described above, the forced shutdown in the present embodiment can protect the power supply system more quickly than the fail-safe process by the microcomputer 50. In this case, the fail-safe process by the microcomputer 50 is a control that prioritizes certainty, whereas the forced interruption in the present embodiment can be regarded as a control that prioritizes rapidity.

Furthermore, in this embodiment, the overcurrent signal output from the latch circuit 62 is reset by the microcomputer 50. In the present embodiment, for example, after the power supply system is once shut down by forced shut-off, the overcurrent determination of the microcomputer 50 does not determine that overcurrent is flowing, that is, when the current value is determined to be normal. The overcurrent signal output from the latch circuit 62 may be reset. In this case, if it is not determined that overcurrent is flowing in the overcurrent determination of the microcomputer 50, the overcurrent generation can be regarded as temporary (mixed noise, etc.) and the forcibly opened switch is closed again. The power supply system can be restored. That is, in such a configuration, in addition to being able to quickly respond when an overcurrent occurs, it is possible to cope with a recovery from an erroneous determination of overcurrent.

According to the embodiment described above in detail, the following excellent effects can be obtained.

When an overcurrent occurs in the power supply system, the fail-safe process by the microcomputer 50 takes time for overcurrent determination and the like, and it is considered that a delay occurs in the opening of the switch, which may cause inconvenience associated with the overcurrent. In consideration of this point, the detection signal input from the

current detection units

41 and 42 is compared with a predetermined overcurrent determination value using the comparison circuit unit 60 and the cutoff circuit unit 70 (electric circuit) separately from the microcomputer 50. An overcurrent signal indicating the occurrence of overcurrent is output based on the comparison result, and the

switches

21 and 22 are opened independently of the opening command from the microcomputer 50 based on the overcurrent signal. In other words, in this case, for example, the time required for overcurrent determination in the microcomputer 50 (timing t2 to timing t3) is detected by detecting the overcurrent and opening the opening / closing section by a circuit unit of a different system different from the fail-safe process by the microcomputer 50. ) Can be omitted, and the overcurrent can be cut off quickly. Thereby, when an overcurrent occurs, the power supply system can be protected quickly.

According to the above configuration, even if a closing (on) command is continuously output from the microcomputer 50 after the occurrence of an overcurrent, the closing drive signal from the driving circuit 52 is invalidated by the cutoff circuit unit 70, Accordingly, the

switches

21 and 22 are forcibly opened. Therefore, the

switches

21 and 22 can be opened without operating the microcomputer open / close command, and as a result, it is possible to respond quickly when an overcurrent occurs.

Moreover, since the cutoff circuit unit 70 opens the

switches

21 and 22 before the bypass switch 31 is switched from the open state to the closed state when an overcurrent signal is input, the bypass switch 31 is closed. The

switches

21 and 22 can be opened without waiting for this. Furthermore, since the bypass switch 31 is a mechanical relay, the time required for relay connection (timing t3 to timing t4) can be saved. Thereby, an overcurrent can be interrupted more rapidly.

Further, when the

switches

21 and 22 are opened by the shut-off circuit unit 70, the microcomputer 50 does not output an open (off) command for the

switches

21 and 22. It can be avoided that 31 is closed. As a result, it is possible to prevent an overcurrent from unintentionally flowing to the bypass path L0 and to prevent the fuse 30 from being blown.

In the annealing process for the detection values of the

current detection units

41 and 42, the smaller the degree of annealing, the better the response than when the degree of annealing is larger. In consideration of this point, the second smoothing process in the second filter 51b is set to have a smaller smoothing degree than the first smoothing process in the first filter 51a. The detected signal (current value Ib) is more responsive than the detection signal (current value Ia) input to the microcomputer 50. Thereby, the comparison circuit unit 60 can detect the overcurrent more quickly.

(Second Embodiment)
Next, the second embodiment will be described focusing on differences from the first embodiment. Such a power supply system will be described with reference to FIG. In the figure, for convenience of explanation, the same reference numerals are given to the configuration similar to that of FIG. 1 and the description is omitted as appropriate. Further, the microcomputer 50, the comparison circuit unit 60, the cutoff circuit unit 70, etc. are not shown.

In the battery unit U shown in FIG. 9, the lead storage battery 11, the starter 14, and the electrical load 15 are connected to the output terminals T1 and T0, the ISG 17 (Integrated Starter Generator) as a generator is connected to the output terminal T2, and the output terminal An electric load 16 is connected to T3. The ISG 17 functions as a power generator that generates electric power (regenerative power generation) by rotating the engine output shaft, and also has a power running function that applies rotational force to the engine output shaft. In addition, when ISG17 exhibits a power running function (power running drive), electric power will be supplied from each storage battery 11 and 12, and ISG 17 in such a case can be regarded as an electric load. In FIG. 9, among the

electric loads

15 and 16, the electric load 16 includes a constant voltage request load. Note that another electrical load may be connected to the output terminal T2.

In the battery unit U, the first switch 21 is provided in the energization path L1, and the second switch 22 is provided in the energization path L2. One end of the branch path L3 is connected to a connection point N2 between the output terminal T1 and the first switch 21 in the energization path L1, and between the lithium ion storage battery 12 and the second switch 22 in the energization path L2. One end of the branch path L4 is connected to the connection point N4, and the other ends of the branch paths L3 and L4 are connected at an intermediate point N3. Further, the intermediate point N3 and the output terminal T3 are connected by the energization path L5.

The third switch 23 and the fourth switch 24 are provided on the branch paths L3 and L4, respectively. The third switch 23 and the fourth switch 24 are each composed of a semiconductor switch such as a MOSFET. Power can be supplied from the storage batteries 11 and 12 to the electric load 16 through the paths L3 to L5. The branch path L3 is provided with a third current detector 43 that detects a current flowing through the third switch 23, and the branch path L4 is provided with a fourth current detector 44 that detects a current flowing through the fourth switch 24. .

The battery unit U is provided with bypass paths L0 and L6 that allow the lead storage battery 11 to be connected to the electric load 16 without using the switches 21 to 24 in the unit. Specifically, the battery unit U is provided with a bypass path L0 that connects the output terminal T0 and the connection point N1 on the energization path L1, and a bypass path L6 that connects the connection point N1 and the output terminal T3. Is provided. A bypass switch 31 is provided on the bypass path L0, and a bypass switch 32 is provided on the bypass path L6. The bypass switches 31 and 32 are, for example, normally closed relay switches.

By closing both the bypass switches 31, 32, the lead storage battery 11 and the electric load 16 are electrically connected even if the switches 21 to 24 are all off.

The above switches 21 to 24 and bypass switches 31 and 32 are on / off controlled (open / close controlled) by the microcomputer 50. In this case, for example, on / off of each of the switches 21 to 24 is controlled based on the storage state of each of the storage batteries 11 and 12. Thereby, charging / discharging is implemented using the lead storage battery 11 and the lithium ion storage battery 12 selectively. The bypass switches 31 and 32 are basically kept open when the power supply system is in operation, and are switched to the closed state when the operation is stopped.

Also in the above power supply system, it is possible to perform forced shut-off by hardware (comparison circuit unit 60 and shut-off circuit unit 70). That is, based on the current values detected by the current detection units 41 to 44, the comparison circuit unit 60 detects an overcurrent, and the cutoff circuit unit 70 closes the switches 21 to 24 output from the microcomputer 50 ( By turning off the ON command, the switches 21 to 24 can be forcibly opened. In this case, the bypass switches 31 and 32 are maintained in the open (off) state by maintaining the close (on) commands of the switches 21 to 24. As a result, overcurrent can be interrupted more rapidly than the fail-safe process by the microcomputer 50 and without conducting the bypass paths L0 and L6, and the power supply system can be suitably protected.

(Other embodiments)
In the above-described embodiment, when the switch is forcibly opened by the shut-off circuit unit 70, the switch closing (ON) command output from the microcomputer 50 is continued. However, the present invention is not limited to this, and any configuration may be used as long as the bypass switch 31 is not closed after the switch is forcibly opened. For example, after the switch is forcibly opened, even when an open (off) command is output from the microcomputer 50, a process for invalidating the off command may be performed, or the fail safe process itself of the microcomputer 50 may be stopped. It is good.

In the above embodiment, the detection value detected by the current detection unit is input to the microcomputer 50 and the comparison circuit unit 60 via two

different filters

51a and 51b. It is good also as a structure input into the microcomputer 50 and the comparison circuit part 60, respectively. That is, in this case, the same annealing process is performed on the detection signal input to the microcomputer 50 and the signal input to the comparison circuit unit 60.

In the above embodiment, when the switch is forcibly opened by the cutoff circuit unit 70, the bypass switches 31 and 32 are not closed, but this may be changed. Since the comparison circuit unit 60 is configured with emphasis on responsiveness, a case where an overcurrent signal is erroneously output based on noise can be considered. In such a case, the switch is opened even though no overcurrent actually occurs. In consideration of this point, when the switch is forcibly opened by the cutoff circuit unit 70, the bypass switch 31 may be closed after a predetermined time has elapsed since the switch was opened. In such a configuration, for example, the maintenance of the switch closing (ON) command is canceled after a predetermined time has elapsed. By intentionally closing the bypass switch 31 in this manner, it can be determined whether or not the detection of the overcurrent in the comparison circuit unit 60 was a false detection. Furthermore, in the case of erroneous detection, the power supply to the electric load 16 can be resumed, that is, the power supply system can be restored.

-The forced shutdown in the above embodiment may be applied to other power supply systems. As another power supply system, for example, a power supply system having only a lead storage battery 11 as a voltage source and provided with a switch in a path connecting the lead storage battery 11 and the electric load 16 can be cited. Moreover, you may apply to the power supply system which has the lead storage battery 11 and a generator as a voltage source, and charges the lead storage battery 11 from a generator. Note that these power supply systems may not have a bypass path.

In the above embodiment, the lead storage battery 11 is provided as the storage battery and the lithium ion storage battery 12 is provided. However, this may be changed. For example, instead of the lithium ion storage battery 12, other high-density storage batteries such as nickel-hydrogen batteries may be used. In addition, a capacitor can be used as at least one of the storage batteries.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A voltage source (11, 12, 13, 17), an electric load (16, 17) supplied with electric power from the voltage source, and an electric path (L1 to L4) connecting the voltage source and the electric load. An open / close unit (21 to 24) that opens or closes the electrical path, and a control unit that outputs an open command to open the open / close unit and a close command to close the open / close unit to control opening / closing of the open / close unit (50) and a current detection unit (41 to 44) for detecting a current flowing through the opening / closing unit,
The control unit receives a detection signal from the current detection unit, and overloads the switching unit based on the detection signal when the power is supplied from the voltage source to the electrical load through the switching unit. A power supply system that outputs the opening command based on the determination and opens the opening and closing unit,
A comparison circuit unit that receives a detection signal of the current detection unit, compares the detection signal with a predetermined overcurrent determination value, and outputs an overcurrent signal indicating the occurrence of overcurrent based on the comparison result (60)
When the overcurrent signal is input, a shut-off circuit unit (70) that opens the open / close unit independently of an open command output from the control unit and interrupts the overcurrent;
Power supply system comprising.
A drive circuit (52) for inputting the opening command and the closing command from the control unit and driving the opening / closing unit to open and close based on each command,
The said interruption | blocking circuit part opens the said opening / closing part by invalidating the closing drive signal output with respect to the said opening / closing part from the said drive circuit, when the said overcurrent signal is input. Power system.
A bypass switch (31, 32) provided in a bypass path (L0, L6) for connecting the voltage source and the electric load by bypassing the opening / closing section, and opening or closing the bypass path;
A bypass circuit section (C1) for closing the bypass switch based on the output of the opening command from the control section,
The control unit outputs the opening command when it is determined that an overcurrent flows through the opening / closing unit based on the detection signal, and the opening / closing is performed after the bypass switch is switched from an open state to a closed state. To open the part,
3. The power supply system according to claim 1, wherein, when the overcurrent signal is input, the shut-off circuit unit opens the opening / closing unit before the bypass switch is switched from an open state to a closed state.
4. The power supply system according to claim 3, wherein the control unit does not output the opening command of the opening / closing unit when the opening / closing unit is opened by the interrupting circuit unit based on the overcurrent signal.
The power supply system according to claim 3 or 4, wherein the bypass switch is a mechanical relay.
The voltage source includes a first storage battery (11) and a second storage battery (12) that are connected in parallel to each other, and is provided in series in the energization path between the first storage battery and the second storage battery as the open / close section. 1 opening / closing part (21, 23) and 2nd opening / closing part (22, 24), the 1st electric current detection part (41, 43) and the 2nd electric current detection part (42, 44) which detect the electric current which flows through each said opening / closing part. And an electrical load is connected to an intermediate point between the first opening and closing part and the second opening and closing part,
The control unit outputs the close command and the open command to the open / close units, and controls the open / close of the open / close units.
The bypass path connects the voltage source and the electric load by bypassing the first opening / closing part,
The power supply according to any one of claims 3 to 5, wherein the bypass circuit section closes the bypass switch based on the opening command being output from the control section to both of the opening / closing sections. system.
The detection signal input to the control unit is obtained by performing a first smoothing process that suppresses a change in the detection value of the current detection unit. The detection signal input to the comparison circuit unit is the current signal. The second smoothing process for suppressing the change in the detection value of the detection unit is performed,
The power supply system according to any one of claims 1 to 6, wherein the second smoothing process is set to have a smaller smoothing degree than the first smoothing process.