JP2020098140A - Switch fault detection device - Google Patents

Abstract

To enable performing fault diagnosis of a switch in a connected state of a battery and a load, while suppressing power consumption, in a circuit on which a plurality of switches are arranged in parallel between the battery and the load.SOLUTION: A switch fault detection device connected between a battery and a load comprises: a plurality of switches; a first branch path which connects the battery to a first end of a respective switch, and includes a plane surface part; a second branch path which connects the load to a second end of a respective switch; a non-contact type current sensor disposed at a position overlapped with the plane surface part of the first branch path in plan view; and a control unit which selects an inspection object switch from the plurality of switches, and performs fault detection of the inspection object switch, on the basis of changes in a measurement value of the non-contact type current sensor when switching between ON and OFF states of the inspection object switch, while maintaining the ON state of the other switches.SELECTED DRAWING: Figure 1

Description

The present invention relates to a switch failure detection device connected between a battery and a load.

For example, in a vehicle equipped with a load related to safety such as an advanced driver assistance system (ADAS), a backup battery is provided so that the load can be supplied even if the main battery fails. A sub battery is provided.

Generally, the main battery and the sub-battery are connected in parallel to the load, but when the main battery fails, for example, when the ground fault occurs, it is necessary to electrically disconnect the main battery from the load. For this reason, a switch is provided between the main battery and the load. Normally, this switch is turned off when a main battery failure is detected in the on state, but it is reliably switched off when necessary. It is required to be carried out while and are electrically connected.

Patent Document 1 describes a device that diagnoses a failure of a switch that connects a battery and a load in a state where the battery and the load are connected. As shown in FIG. 7, in this device, a sub battery 520 is connected in parallel to a main battery 510 that supplies power to a load 530, and a first switch 551 and a second switch 551 are connected between the battery 510 and the load 530. They are connected by a parallel circuit of 552.

The first switch 551 is connected to a resistor R1 whose one end is grounded, and is also connected to a diode D1 that blocks a current flowing from the load 530. The second switch 552 is connected to the resistor R2 whose one end is grounded, and is also connected to the diode D2 that blocks the current flowing from the load 530.

The control unit 540 controls ON/OFF of the first switch 551 and the second switch 552, measures the voltage generated in the resistors R1 and R2, and diagnoses the failure of the first switch 551 and the second switch 552. Specifically, the on/off state of the first switch 551 is changed while the second switch 552 is in the on state, the failure of the first switch 551 is diagnosed based on the voltage generated in the resistor R1, and the first switch 551 is in the on state. Then, the on/off of the second switch 552 is changed, and the failure of the second switch 552 is diagnosed based on the voltage generated in the resistor R2.

JP, 2005-095442, A

According to the invention described in Patent Document 1, the failure diagnosis of the switches 551 and 552 can be performed in a state where the battery 510 and the load 530 are connected. However, during connection between the battery 510 and the load 530, current always flows from the battery 510 to at least one of the resistors R1 and R2, and extra power is consumed.

Therefore, the present invention enables a switch failure diagnosis to be performed in a state where a battery and a load are connected while suppressing power consumption in a circuit in which a plurality of switches are provided in parallel between the battery and the load. The purpose is to

In order to solve the above problems, a switch failure detection device of the present invention is a switch failure detection device connected between a battery and a load, wherein the switch failure detection device includes a plurality of switches, the battery, and a first end of each switch. And a second branch path connecting the load and the second end of each switch, and a position that overlaps the plane section of the first branch path in plan view. The non-contact type current sensor arranged in the, and the non-contact type when the inspection target switch is selected from the plurality of switches, and the on-off of the inspection target switch is switched while maintaining the ON state of other switches. And a control unit that determines a failure of the switch to be inspected based on a change in the measured value of the current sensor.
Here, the non-contact current sensor uses a coreless magnetic sensor, and can have magnetic flux density sensitivity in parallel with the sensor surface.
In addition, the control unit determines that the inspection target switch is defective when the measurement value of the non-contact current sensor does not change by a predetermined reference or more when the inspection target switch is turned off. You can
In addition, a substrate on which the non-contact type current sensor is arranged may be further provided, and the first branch path may be configured by a bus bar, and the non-contact type current sensor may be covered above the substrate.
Alternatively, it may further include a substrate on which the non-contact type current sensor is arranged on one surface, and the first branch path may be formed in a wiring pattern on the other surface of the substrate.
Further, the non-contact type current sensor may be arranged at a position overlapping with a region where the shortest path between the battery and each switch intersects in the first branch path in a plan view.

According to the present invention, in a circuit in which a plurality of switches are provided in parallel between a battery and a load, it is possible to perform switch failure diagnosis while connecting the battery and the load while suppressing power consumption. ..

It is a block diagram which shows typically the structure of the switch failure detection apparatus which concerns on this embodiment. It is a figure explaining the arrangement location of a non-contact type current sensor. 7 is a flowchart illustrating a switch failure diagnosis operation performed by the control unit. It is a figure explaining the electric current path in a conduction state and an interruption state. It is a block diagram showing another example of a switch. It is a figure which shows the example of a branch path at the time of providing two switches. It is a block diagram which shows the conventional switch failure diagnostic apparatus.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing the configuration of a switch failure detection device 100 according to this embodiment. As shown in the figure, the switch failure detection device 100 is connected between the main battery 510 and the load 530. In the example of this figure, the sub-battery 520 is connected in parallel on the load 530 side, but the present invention can be applied even if the sub-battery 520 is omitted.

The switch failure detection device 100 includes a first switch 111, a second switch 112, a third switch 113, a first branch path 121, a second branch path 122, a non-contact current sensor 130, and a controller 140.

The first switch 111, the second switch 112, and the third switch 113 are arranged, for example, on a substrate and are connected in parallel by a first branch path 121 and a second branch path 122. Hereinafter, the first switch 111, the second switch 112, and the third switch 113 connected in parallel are collectively referred to as a switch 110 unless it is necessary to distinguish them.

The switch 110 is composed of a pair of N-channel MOSFETs. Specifically, the first switch 111 is composed of FETa1 and FETb1 whose sources are connected to each other and their gates are connected to each other, and the second switch 112 is composed of FETa2 and FETb2 whose sources are connected to each other and their gates are connected to each other. The third switch 113 is composed of FETa3 and FETb3 whose sources are connected to each other and whose gates are connected to each other. Therefore, the two MOSFETs forming each switch 110 are switched on and off at the same time.

The drains of the FETa1, FETa2, and FETa3 are connected to the first branch path 121, and the drains of the FETb1, FETb2, and FETb3 are connected to the second branch path 122.

The first branch path 121 is formed to include a planar portion having a certain width, and has a side connected to the main battery 510 and a side connected to the switch 110. In plan view, a convex shape is formed on the side connected to the main battery 510, and the main battery 510 is connected to this convex portion. The side connected to the switch 110 has a comb shape having teeth corresponding to the number of switches 110, and the drains of the FETa1, FETa2, and FETa3 are connected to the respective tooth portions.

The second branch path 122 also has a certain width, and has a side connected to the load 530 and a side connected to the switch 110. A convex shape is formed on the side connected to the load 530, and the load 530 and the sub-battery 520 are connected to this convex portion. The side connected to the switch 110 has a comb shape having teeth corresponding to the number of the switches 110, and the drains of the FETb1, FETb2, and FETb3 are connected to the respective tooth portions.

However, the first branch path 121 and the second branch path 122 need only have a shape that connects the switch 110 to the main battery 510 or the load 530, and may not have a convex portion or a comb portion.

The 1st branch path 121 and the 2nd branch path 122 can be comprised by the bus bar of a metal plate, for example. Alternatively, the wiring pattern may be formed on the substrate.

The non-contact current sensor 130 is an element that measures a current in a non-contact manner with a current path of a measurement target. For example, an element that measures a current based on the magnetic flux density detected using a coreless magnetic sensor such as a Hall IC can be used, and a current sensor having a magnetic flux density sensitivity parallel to the element surface is particularly preferable.

The non-contact type current sensor 130 is arranged near the first branch path 121. Specifically, it is a position that overlaps with the plane portion of the first branch path 121 in a plan view, and the position where the shortest path between the main battery 510 connection portion of the convex portion and the switch 110 connection portion of each comb-shaped tooth portion intersects. Place as a guide. Therefore, the first branch path 121 is formed such that this area is flat. As a result, the non-contact type current sensor 130 can detect the change in the current distribution (magnetic flux density) in the plane portion with high sensitivity.

For example, when the first branch path 121 and the second branch path 122 are configured by bus bars, the first branch path 121 is arranged above the substrate 150 as shown in the schematic side view of FIG. The non-contact type current sensor 130 is arranged on the upper surface of the substrate 150, that is, the surface corresponding to the bus bar. When the first branch path 121 and the second branch path 122 are formed on the front surface of the substrate 150 by a wiring pattern, as shown in the schematic side view of FIG. The current sensor 130 is arranged. The non-contact type current sensor 130 may be arranged on the second branch path 122 side.

The control unit 140 can be configured by a microcomputer or the like, performs switching control of the switch 110, and performs failure diagnosis of the switch 110 based on a change in the measurement value of the non-contact current sensor 130. Therefore, the control unit 140 connects each common gate of the switch 110 and the non-contact type current sensor 130.

The failure diagnosis operation of the switch 110 performed by the control unit 140 will be described with reference to the flowchart of FIG. The failure diagnosis operation of the switch 110 can be performed in a state where the power supply from the main battery 510 to the load 530 is continued.

First, all the switches 110 are turned on (S101). However, all the switches 110 are normally on. Then, the non-contact current sensor 130 starts measuring the current flowing through the first branch path 121 (S102).

Next, one of the switches 110 is selected as the inspection target switch (S103), and the inspection target switch 110 is turned off (S104). Since the switches 110 other than the inspection target are in the ON state, the connection state between the main battery 510 and the load 530 is maintained. The switches to be inspected can be selected in a predetermined order, for example.

The control unit 140 determines whether or not the current value measured by the non-contact current sensor 130 has changed by a predetermined reference value or more in synchronization with the turning off of the switch 110 (S105). As a result, when the change is equal to or more than the predetermined reference (S105: Yes), it is determined that the switch 110 to be inspected is not stuck on (S106). On the other hand, when there is no change equal to or greater than the predetermined reference (S105: No), it is determined that the switch 110 to be inspected is stuck on (S107).

This is because, as shown in FIGS. 4A to 4C, the current distribution state in which the path corresponding to each switch 110 is in the conductive state and the current distribution status in the case where any one of the paths is cut off are different. This is what was used. In the present embodiment, a change in the magnetic flux density based on a change in the current distribution state is detected by the non-contact type current sensor 130 having a sensitivity on the plane parallel to the plane through which the current flows.

Here, it has been confirmed by simulation that the change in the current distribution state significantly affects the current measurement value of the non-contact current sensor 130. In addition, it is desirable that the non-contact current sensor 130 is arranged at a position where the amount of change in the measured value becomes the largest due to the interruption of the current path.

When the determination of the inspection target switch 110 is completed, the inspection target switch 110 is turned back on (S108). It is also possible to detect the OFF fixation of the switch 110 to be inspected based on the change in the current value when the switch 110 to be inspected is switched from OFF to ON.

If there is an undetermined switch 110 (S109: No), it is selected as a switch to be inspected (S103), and the subsequent determination process is repeated. When the determination is completed for all the switches 110 (S109: Yes), this operation ends.

The present invention is not limited to the above embodiment. For example, the switch 110 is not limited to the configuration in which the sources of the pair of N-channel MOSFETs are connected to each other. For example, as shown in FIG. 5, one N-channel MOSFET may be used. Alternatively, a P-channel MOSFET or a micro relay having a relay contact may be used.

Further, the number of switches 110 provided in parallel is not limited to three. In order to detect a failure while maintaining the electrical connection between the main battery 510 and the load 530, two or more switches 110 may be provided in parallel. FIGS. 6A and 6B show examples of the shape of the first branch path 121 when the number of the switches 110 is two. In either case, the non-contact type current sensor 130 is arranged at the branch portion.

As described above, according to the switch failure detection device 100 of the present embodiment, the configuration in which the current is passed through the resistor for voltage detection is abolished, and the non-contact type current sensor 130 is arranged in the branch path portion connected to the switch 110. Since the change in the current due to the switching of the switch is detected, it is possible to perform the failure diagnosis of the switch with the battery and the load connected while suppressing the power consumption.

100 Switch Failure Detection Device 110 Switch 121 First Branch Path 122 Second Branch Path 130 Non-contact Current Sensor 140 Control Unit 150 Substrate 510 Main Battery 520 Sub Battery 530 Load 540 Control Unit

Claims (6)

A switch failure detection device connected between a battery and a load,
Multiple switches,
A first branch path connecting the battery and a first end of each switch and having a flat portion;
A second branch path connecting the load and a second end of each switch;
A non-contact type current sensor arranged at a position overlapping the planar portion of the first branch path in plan view,
Selecting a test target switch from the plurality of switches, while maintaining the other switch on state, based on the change in the measurement value of the non-contact current sensor when switching the test target switch on and off A control unit for determining a failure of the switch to be inspected,
A switch failure detection device comprising: The switch failure detection device according to claim 1, wherein the non-contact type current sensor uses a coreless magnetic sensor and has magnetic flux density sensitivity parallel to a sensor surface. The control unit determines that the switch to be inspected has failed if the measurement value of the non-contact current sensor does not change more than a predetermined reference value when the switch to be inspected is turned off. The switch failure detection device according to claim 1 or 2. Further comprising a substrate on which the non-contact type current sensor is arranged,
The switch failure detection device according to claim 1, wherein the first branch path is configured by a bus bar and covers the non-contact type current sensor above the substrate. Further comprising a substrate on which the non-contact type current sensor is arranged on one surface,
The switch failure detection device according to claim 1, wherein the first branch path is formed as a wiring pattern on the other surface of the substrate. The non-contact type current sensor is arranged at a position where it overlaps in a plan view in an area where the shortest path between the battery and each switch intersects in the first branch path. 2. A switch failure detection device according to item 1.

Images