JP2017136971A - Contactor failure determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it easier to identify a failure cause of a contactor.SOLUTION: A contactor failure determination device 10 determines a failure of a contactor group including: a positive electrode side contactor 30 provided on a positive electrode side power line L1 connecting a positive electrode of a battery 22 supplying electric power to load equipment and a positive electrode of the load equipment; and a negative electrode side contactor 32 provided on a negative electrode side power line L2 connecting a negative electrode of the battery 22 and a negative electrode of the load equipment. In the case where abnormality of a driving circuit voltage of any contactor occurs during a start-up of the load equipment, the contactor failure determination device 10 determines that there is a possibility that the contactor driven by a driving circuit has a failure caused by the driving circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a contactor failure determination device that determines whether or not a contactor group provided in a power supply line from a battery has a failure.

Conventionally, a contactor (positive electrode side) that connects / disconnects an electrical connection to a power line between a battery mounted as a driving power source of an electric vehicle such as an electric vehicle or a hybrid vehicle and a load device (for example, a driving motor). Contactor and negative electrode side contactor) are provided.
In addition, since the power supply for driving the electric vehicle is high voltage, a precharge contactor is provided in parallel with the positive contactor to suppress inrush current when the high voltage power supply is started (when the high voltage circuit is connected). .

  The above contactor group is a safety mechanism of the power supply circuit, and it is necessary to periodically check whether these contactors operate normally. For this reason, in general, the contactor is opened and closed at the start of the electric vehicle (when the high voltage circuit is connected) and at the end (when the high voltage circuit is disconnected) to determine whether the contactor has failed. Yes.

  For example, in Patent Document 1 below, when the ignition key position is switched from the OFF position to the ON position, the master control unit performs an HV battery abnormality diagnosis. Based on the combination of the power supply side voltage detected by the power supply side voltage sensor and the load side voltage detected by the load side voltage sensor, the master control unit has an error in either the system main relay, the high voltage fuse, or the stacked battery module. Whether or not has occurred is determined.

  Further, for example, the following Patent Document 2 is an invention relating to an electric power supply device in an electric motorcycle, and a main battery, a main contactor and a precharge contactor that connect and disconnect the main battery and an inverter circuit by turning on and off, and these A sub-battery that is a drive power source of the contactor, a BMU that drives and controls these contactors, and a voltage sensor that detects a voltage value of the sub-battery, and processes related to contactor failure determination are integrated by the BMU. .

JP 2001-327001 A JP2013-248971A

Generally, when a failure occurs in the contactor, the user brings the electric vehicle to a repair shop or the like for repair. Causes of contactor failure include contactor body failure, contactor drive circuit failure, and failure of a control unit (such as ECU) that controls the contactor (program bug, etc.). Although the presence or absence of a group failure can be determined, the cause of the failure cannot be determined.
Therefore, all the factors that cause the contactor failure must be examined during repair, and repair may take time.
The present invention has been made in view of such circumstances, and an object thereof is to make it easier to identify the cause of failure of a contactor.

In order to achieve the above-mentioned object, a contactor failure determination device according to claim 1 is a positive electrode provided on a positive power line connecting a positive electrode of a battery that supplies power to a load device and a positive electrode of the load device. A contactor failure determination device for determining a failure of a contactor group including a side contactor and a negative electrode side contactor provided on a negative electrode side power line connecting a negative electrode of the battery and a negative electrode of the load device, A driving circuit voltage detecting unit for detecting a driving circuit voltage of each contactor of the group, and when any of the driving circuit voltages is abnormal during activation of the load device, the driving circuit is driven by the driving circuit And a failure determination unit that determines that the contactor has a possibility of failure due to the driving circuit.
In the contactor failure determination device according to a second aspect of the present invention, the failure determination unit includes a battery voltage of the battery, and the contact between the positive power line and the negative power line on the load device side of the contactor group. When the time change rate of the absolute value of the difference from the load side voltage is equal to or greater than a predetermined value, it is determined that any of the contactor groups may have a failure, and the time change rate is equal to or greater than the predetermined value. If there is an abnormality in the driving circuit voltage at the determined timing, it is determined that the contactor driven by the driving circuit has a possibility of failure due to the driving circuit.
The contactor failure determination device according to a third aspect of the present invention is directed to any one of the contactor groups when the failure determination unit has no abnormality in the driving circuit voltage at a timing when the time change rate becomes a predetermined value or more. It is determined that there is a possibility of a failure caused by other than the driving circuit.
In the contactor failure determination device according to a fourth aspect of the present invention, the failure determination unit sequentially turns on and off the contactor group at the time of starting and ending the load device, and the load side voltage changes in a predetermined manner along with the on / off. In this case, it is determined that the contactor driven by the driving circuit is broken.

According to the first aspect of the present invention, if there is an abnormality in the drive circuit voltage of any of the contactors during startup of the load device, the contactor driven by the drive circuit may be damaged due to the drive circuit. Therefore, it is advantageous to identify the cause of the contactor failure at an early stage and enable quick repair. In addition, it is possible to detect the possibility of contactor failure during start-up of the load device, which is advantageous in detecting the possibility of contactor failure early compared to the case where failure determination is performed only at the time of start-up and termination. It becomes.
According to the second aspect of the present invention, when the time change rate of the absolute value of the difference between the battery voltage and the load side voltage is equal to or greater than a predetermined value, and the drive circuit voltage is abnormal at the same timing, Since it is determined that there is a possibility of the failure caused, it is advantageous for improving the accuracy of the failure determination.
According to the invention of claim 3, when the time change rate of the absolute value of the difference between the battery voltage and the load side voltage is not less than a predetermined value and there is no abnormality in the driving circuit voltage at the same timing, other than the driving circuit Therefore, it is possible to narrow down the cause of failure of the contactor to other than the drive circuit, which is advantageous in efficiently investigating the cause of failure.
According to the fourth aspect of the present invention, the contactor groups are sequentially turned on and off at the start and end of the load device, and the presence or absence of the failure is determined based on the change in the load side voltage accompanying the on / off, thereby preventing erroneous detection of the failure. This is advantageous.

It is explanatory drawing which shows the structure of the high voltage circuit 20 with which the contactor failure determination apparatus 10 was mounted. 3 is a circuit diagram illustrating a configuration example of a driving circuit voltage detection unit 102. FIG. 5 is a flowchart showing processing by a failure determination unit 104. It is a graph which shows an example of the time change of battery voltage VB and load side voltage VC.

Exemplary embodiments of a contactor failure determination device according to the present invention will be explained below in detail with reference to the accompanying drawings.
In the present embodiment, it is assumed that the load device is a drive motor that drives an electric vehicle (electric vehicle), and the battery is a drive battery for the electric vehicle.

FIG. 1 is an explanatory diagram showing a configuration of a high voltage circuit 20 on which the contactor failure determination device 10 is mounted.
The contactor failure determination device 10 according to the present embodiment is realized by performing a failure determination process, which will be described later, by a BMU (Battery Management Unit) 12 of an electric vehicle, and an electric vehicle driving power source (battery 22). It is mounted on the high-voltage circuit 20 including it.

The battery 22 is mounted as a driving power source for a driving motor 24 that is a load device in the electric vehicle, and supplies power to the driving motor 24.
The battery 22 is an assembled battery in which a plurality of battery cells are connected in series, and a direct current from the battery 22 is converted into an alternating current and supplied to the drive motor 24 in the positive power supply line L1 connected to the positive electrode. The negative electrode of the inverter 26 is connected to the negative power supply line L2 connected to the negative electrode of the inverter 26.
The battery 22 is a high voltage power supply, and in this embodiment, the battery voltage VB is assumed to be 300V, for example.
A battery voltmeter 40 that detects the battery voltage is connected to both ends of the battery 22. The detection value of the battery voltmeter 40 is output to the BMU 12.

The drive motor 24 is driven by the electric power supplied from the battery 22 and rotates the axle of the electric vehicle.
More specifically, an inverter 26 for converting a direct current supplied from the battery 22 into an alternating current is provided between the drive motor 24 and the battery 22. The drive motor 24 is connected to the alternating current by the inverter 26. The current converted to is supplied.

The inverter 26 includes a switching circuit, a capacitor, and the like. The switching circuit of the inverter 26 is controlled according to a required output to the drive motor 24 by an MCU (Motor Control Unit) (not shown).
Further, the capacitor of the inverter 26 is connected at both ends thereof to the positive power supply line L1 and the negative power supply line L2 on the battery 22 side from the switching circuit, and smoothes voltage fluctuations generated by switching in the switching circuit.
In addition, the inverter 26 is provided with a discharge resistor or the like for discharging the charge stored in the capacitor when the high-voltage circuit 20 of the vehicle is disconnected.

On the power supply lines L1 and L2 between the battery 22 and the inverter 26, a contactor group including a positive contactor 30, a negative contactor 32, and a precharge contactor 34 is provided.
More specifically, the positive electrode side contactor 30 is provided on the positive electrode side power supply line L1 connecting the positive electrode of the battery 22 and the positive electrode of the load device, and the negative electrode side contactor 32 connects the negative electrode of the battery 22 and the negative electrode of the load device. The precharge contactor 34 is provided in parallel with the positive electrode side contactor 30 on the positive electrode side power supply line L1.
In the present embodiment, the precharge contactor 34 is provided in parallel with the positive electrode side contactor 30, but the precharge contactor 34 may be provided in parallel with the negative electrode side contactor 32.

The positive electrode side contactor 30 and the negative electrode side contactor 32 are provided to connect and disconnect the electrical connection between the drive motor 24 and the battery 22 in the high voltage circuit 20. In the following description, the connection state of the high voltage circuit 20 refers to a state where both the positive contactor 30 and the negative contactor 32 are turned on and the drive motor 24 and the battery 22 are electrically connected.
The precharge contactor 34 is provided to prevent an inrush current from flowing through the capacitor in the inverter 26 when the high voltage circuit 20 is connected (starting up). More specifically, a precharge resistor 36 is connected in series to the precharge contactor 34. When the precharge contactor 34 and the negative contactor 32 are turned on, the current flowing through the circuit is limited.
When the high voltage circuit 20 is connected, first, the precharge contactor 34 and the negative contactor 32 are turned on to make the capacitor voltage equal to the battery voltage by the limited current (precharge). Thereafter, the positive contactor 30 is turned on and the precharge contactor 34 is turned off, and the connection process of the high voltage circuit 20 is completed.
The connection of the high voltage circuit 20 activates a high voltage system device, that is, a drive motor 24 that is a load device. That is, when the load device is activated, it means when the high voltage circuit 20 is in a connected state.

The contactor failure determination device 10 described above determines whether or not there is a failure in the contactor group including the positive contactor 30, the negative contactor 32, and the precharge contactor 34.
In the present embodiment, welding (closed sticking maintained in a closed state) will be mainly described as a contactor failure form. However, contactor failure forms include, for example, open sticking maintained in an open state, Also included are control failures (the state is not switched because the control signal is not transmitted but the control signal is not transmitted).

  A load-side voltmeter 42 that detects a voltage therebetween (hereinafter referred to as “load-side voltage”) is connected to the positive-side power line L1 and the negative-side power line L2 on the load device side of the contactor group. The detection value of the load side voltmeter 42 is output to the BMU 12.

The BMU 12 is a control unit that controls the battery 22, and includes a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an EEPROM that holds various data in a rewritable manner, a peripheral circuit, and the like. It is configured to include an interface unit that takes an interface.
The BMU 12 is connected to the activation switch 50 and the notification unit 52.
Activation switch 50 is provided in the driver's seat and accepts activation operation and termination operation of the electric vehicle.
The notification unit 52 notifies the user when the failure determination unit 104 described later determines that a failure has occurred in any of the contactor groups.
As the notification unit 52, various conventionally known notification devices such as a display, an indicator lamp, and a speaker can be used.

  The BMU 12, the contactor group described above, the start switch 50, and the notification unit 52 are driven by the electric power stored in the auxiliary battery 54 provided separately from the battery 22. The auxiliary battery 54 is provided to drive various auxiliary machines in the electric vehicle, and is a battery having a lower voltage (for example, 12V) than the battery 22. That is, the contactor failure determination device 10 is driven using a power supply system different from the high-voltage power supply system that receives power supply from the battery 22.

The BMU 12 includes a drive circuit voltage detection unit 102 that detects each drive circuit voltage of the contactor group, and the failure determination unit 104 is realized by the CPU executing the control program.
FIG. 2 is a circuit diagram illustrating a configuration example of the driving circuit voltage detection unit 102.
A contactor group including the positive electrode side contactor 30, the negative electrode side contactor 32, and the precharge contactor 34 is provided with a driving circuit voltage detection unit 102 as shown in FIG.
The on / off state of each contactor is switched depending on whether or not the coil 60 in the contactor is energized. One end of the coil 60 is connected to the auxiliary battery 54, and the other end is grounded via the transistor 62. When the BMU 12 energizes the transistor 62, current from the auxiliary battery 54 flows to the coil 60 and the contactor is turned on. Become.
The driving circuit voltage detection unit 102 detects the voltage upstream of the transistor 62 and can determine whether or not each driving circuit of the contactor group is operating normally.

The failure determination unit 104 determines whether or not there is a failure in the contactor group (the positive side contactor 30, the negative side contactor 32, and the precharge contactor 34). In particular, in the present embodiment, it is determined whether or not there is a possibility of failure due to the drive circuit of each contactor.
That is, the failure determination unit 104 sequentially turns on and off the contactor group at the time of starting and ending the load device, as in the case of the conventional contactor failure determination, and when the load side voltage VC changes in a predetermined manner along with the on / off. It is determined that a predetermined contactor has failed.
More specifically, the failure determination unit 104 turns off the negative electrode side contactor 32 from the state where both the positive electrode side contactor 30 and the negative electrode side contactor 32 are on at the end of the electric vehicle. If the load-side voltage VC is equal to or higher than the predetermined voltage V1 after turning off the negative-side contactor 32, it is determined that the positive-side contactor 30 has failed (welded) (end-of-life failure determination process).
In addition, failure determination unit 104 first turns on only precharge contactor 34 from the state in which all contactors are turned off when the electric vehicle is started. After the precharge contactor 34 is turned on, when the load side voltage VC becomes equal to or higher than an arbitrary predetermined voltage V2, it is determined that the negative side contactor 32 has failed (welded). When the load side voltage VC does not become equal to or higher than the predetermined voltage V2, the failure determination unit 104 turns off the precharge contactor 34 and then turns on the negative side contactor 32. After the negative electrode side contactor 32 is turned on, when the load side voltage VC becomes equal to or higher than an arbitrary predetermined voltage V3, it is determined that the precharge contactor 34 has failed (welding) (startup failure determination process). .
Note that the failure determination at the time of starting and ending the electric vehicle is not limited to the above-described procedure, and various conventionally known methods can be applied.

In addition to the processing at the time of start-up and end as described above, the failure determination unit 104 constantly monitors the drive circuit voltage of each contactor during the start-up of the load device, and when an abnormality occurs in the drive circuit voltage, It is determined that the contactor driven by the driving circuit has a possibility of failure due to the driving circuit.
In addition, the failure determination unit 104 improves the determination accuracy when the time change rate of the difference between the battery voltage VB of the battery 22 and the load-side voltage VC on the power supply line exceeds a predetermined value. If there is an abnormality in the drive circuit voltage at the timing when the difference becomes a predetermined value or more, the contactor driven by the drive circuit in which the abnormality has occurred is determined. It is determined that there is a possibility of failure due to the driving circuit. If there is no abnormality in the driving circuit voltage at the timing when the difference becomes equal to or greater than the predetermined value, it is determined that there is a possibility of failure in any of the contactor groups other than the driving circuit.

FIG. 3 is a flowchart showing processing by the failure determination unit 104, and shows a series of processing from the start to the end of the electric vehicle.
When the start switch 50 of the electric vehicle is turned on (step S300: Yes), the failure determination unit 104 performs the above-described start-up failure determination process (step S302). If there is a failure in the contactor to be determined (the negative side contactor 32 or the precharge contactor 34) (step S304: Yes), the process proceeds to step S320 and the cause of the failure is identified from the information recorded during the previous travel (step S304). S320).

If there is no failure in the contactor to be determined (step S304: No), the high voltage circuit 20 is connected and the load device (driving motor 24) is activated. The failure determination unit 104 determines whether or not the time change rate of the absolute value of the difference between the battery voltage VB of the battery 22 and the load side voltage VC on the power supply line is equal to or greater than a predetermined value A as shown in the following formula (1). Is determined (step S306).
The reason for monitoring the time change rate of the difference between the battery voltage VB and the load side voltage VC in this way is to avoid the influence of voltage fluctuation or the like due to regeneration of the electric vehicle.

FIG. 4 is a graph showing an example of a time change of the battery voltage VB and the load side voltage VC.
In the graph of FIG. 4, while the battery voltage VB is constant, the load side voltage VC fluctuates up and down greatly after time T1, and returns to substantially the same voltage as the battery voltage VB at time T2.
Such voltage fluctuation occurs when the contactor (the positive contactor 30 or the negative contactor 32) is temporarily turned off for some reason while the high voltage circuit 20 is energized and then turned on again. In this case, there is a high possibility that arc discharge occurs when the contactor returns from OFF to ON, and some of the nodes melt, that is, welding occurs.
That is, in step S306, the battery voltage VB and the load side voltage VC are monitored while the electric vehicle is traveling, thereby monitoring the possibility of welding sequentially.

If the time change rate is not equal to or greater than the predetermined value A (step S306: No), the process proceeds to step S314.
If the time change rate is greater than or equal to the predetermined value A (step S306: Yes), it is determined whether or not there is an abnormality in the drive circuit voltage detected by the drive circuit voltage detector 102 (step S308). As described above, the drive circuit voltage detection unit 102 always detects the drive circuit voltage and records it together with time information. For this reason, it is possible to read out the driving circuit voltage when the time change rate of the difference between the battery voltage VB and the load side voltage VC is equal to or greater than the predetermined value A, and determine whether or not it is normal. The abnormality of the driving circuit voltage includes a case where the difference from the normal voltage becomes a predetermined value or more.

When there is an abnormality in the driving circuit voltage detected by the driving circuit voltage detection unit 102 (step S308: Yes), the driving circuit failure information including the type and time of the contactor in which the voltage abnormality has occurred, the driving circuit voltage value, and the like Is recorded (step S310).
Further, when there is no abnormality in the driving circuit voltage (step S308: No), the voltage value abnormality including the time when the time change rate of the difference between the battery voltage VB and the load side voltage VC becomes equal to or greater than the predetermined value A or the like. Information is recorded (step S312).
Until the start switch 50 of the electric vehicle is turned off and the electric vehicle end process is performed (step S314: No), the process returns to step S306, and the subsequent processes are repeated.

When the start switch 50 of the electric vehicle is turned off (step S314: Yes), the failure determination unit 104 performs the above-described end-time failure determination process (step S316).
If there is no failure in the contactor to be determined (positive electrode side contactor 30) (step S318: No), the processing according to this flowchart is terminated as it is.
On the other hand, when there is a failure in the contactor to be determined (positive contactor 30) (step S318: Yes), the drive circuit voltage detection unit 102 reads the recorded information and identifies the cause of the failure (step S320). ).
That is, when the drive circuit failure information is recorded during traveling, it is determined that the cause of the contactor failure may be the drive circuit. Further, when the driving circuit failure information is not recorded, it is determined that there is a possibility that the failure cause of the contactor is other than the driving circuit. In particular, when voltage value abnormality information is recorded, it is possible to specify the time of occurrence of a failure.
And the alerting | reporting part 52 alert | reports that the failure has arisen in one of the contactor groups, and the cause of failure (step S322), and complete | finishes the process by this flowchart.

  In addition to the driving circuit, the cause of failure of the contactor includes a program of a contactor body and a control unit that controls the contactor. When the contactor main body is the cause, it can be specified when the user who has received the failure notification brings the electric vehicle to a dealer or the like and replaces the contactor. Further, when the drive circuit or the contactor body is not the cause, it can be specified that the cause is the control unit.

  In the present embodiment, the abnormality of the driving circuit voltage is confirmed when the time change rate of the difference between the battery voltage VB and the load-side voltage VC exceeds a predetermined value. However, the driving circuit voltage is constantly monitored. If there is an abnormality, it may be determined that there is a possibility of contactor failure. In addition, the user may be notified when the possibility of failure is detected without waiting for failure determination at the end or at startup.

As described above, according to the contactor failure determination device 10 according to the embodiment, when there is an abnormality in the drive circuit voltage of any contactor during the activation of the load device, the contactor failure determination apparatus 10 is driven by the drive circuit. Since it is determined that the contactor may have a failure due to the driving circuit, it is advantageous in identifying the cause of the contactor failure early and enabling quick repair. In addition, it is possible to detect the possibility of contactor failure during start-up of the load device, which is advantageous in detecting the possibility of contactor failure early compared to the case where failure determination is performed only at the time of start-up and termination. It becomes.
Further, according to the contactor failure determination device 10, when the time change rate of the absolute value of the difference between the battery voltage VB and the load-side voltage VC exceeds a predetermined value, and the drive circuit voltage is abnormal at the same timing, Since it is determined that there is a possibility of failure due to the drive circuit, it is advantageous in improving the accuracy of failure determination.
Further, according to the contactor failure determination device 10, when the time change rate of the absolute value of the difference between the battery voltage VB and the load side voltage VC is not less than a predetermined value and the drive circuit voltage is not abnormal at the same timing, Since it is determined that there is a possibility of a failure caused by other than the driving circuit, the failure cause of the contactor can be narrowed down to other than the driving circuit, which is advantageous in efficiently investigating the failure cause.
Further, according to the contactor failure determination device 10, the contactor groups are sequentially turned on and off at the time of starting and ending the load device, and the presence or absence of the failure is determined based on the change in the load side voltage accompanying the on / off. It is advantageous in preventing the above.

In this embodiment, since the processing unit related to the contactor failure determination is only the BMU 12, the reliability of the determination result is improved as compared to the case where a plurality of processing units such as MCU and ECU are related to the contactor failure determination. Can be made.
In the present embodiment, the BMU 12 has been described as realizing the contactor failure determination device 10, but other processing units mounted on the vehicle, for example, an ECU (Electronic Management Unit) that controls the entire electric vehicle or the MCU described above. You may implement | achieve the contactor failure determination apparatus 10 by.
Even in this case, it is preferable that only one processing unit is involved in the contactor failure determination.

  DESCRIPTION OF SYMBOLS 10 ... Contactor failure determination apparatus, 102 ... Drive circuit voltage detection part, 104 ... Failure determination part, 12 ... BMU, 20 ... High voltage circuit, 22 ... Battery, 24 ... Drive motor, 26 …… Inverter, 30 …… Positive side contactor, 32 …… Negative side contactor, 34 …… Precharge contactor, 36 …… Precharge resistor, 40 …… Battery voltmeter, 42 …… Load side voltmeter, 50 …… Start switch, 52 ... notification unit, 54 ... auxiliary battery, L1 ... positive power line, L2 ... negative power line

Claims (4)

A positive-side contactor provided on a positive-side power supply line that connects a positive electrode of a battery that supplies power to a load device and a positive electrode of the load device, and a negative-side power supply line that connects a negative electrode of the battery and a negative electrode of the load device A contactor failure determination device for determining a failure of a contactor group including a negative electrode side contactor provided on the top;
A driving circuit voltage detector for detecting a driving circuit voltage of each contactor of the contactor group;
Failure determination that determines that a contactor driven by the drive circuit may have a failure due to the drive circuit when any of the drive circuit voltages is abnormal during the activation of the load device And
A contactor failure determination device comprising: The failure determination unit is a time change of an absolute value of a difference between a battery voltage of the battery and a load side voltage between the positive side power line and the negative side power line on the load device side from the contactor group. When the rate exceeds a predetermined value, it is determined that any of the contactor groups may have a failure, and the drive circuit voltage is abnormal at the timing when the time change rate exceeds the predetermined value. The contactor driven by the driving circuit determines that there is a possibility of failure due to the driving circuit.
The contactor failure determination apparatus according to claim 1. If there is no abnormality in the driving circuit voltage at the timing when the time change rate becomes equal to or greater than a predetermined value, the failure determination unit may cause a failure caused by something other than the driving circuit in any of the contactors. Judge that there is
The contactor failure determination device according to claim 2, wherein: The failure determination unit sequentially turns on and off the contactor group at the time of starting and ending the load device, and a contactor driven by the driving circuit when the load side voltage changes in accordance with the on / off state Judge that it is malfunctioning,
The contactor failure determination device according to any one of claims 1 to 3, wherein

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