JP7119401B2 - FAILURE DIAGNOSIS DEVICE, POWER STORAGE DEVICE, FAILURE DIAGNOSIS METHOD - Google Patents

Description

The present invention relates to a technique for diagnosing a failure of a current interrupting device.

A lithium-ion secondary battery is equipped with a battery monitoring unit (hereinafter referred to as BMU) to prevent overcharge and overdischarge. The BMU monitors the state of the battery and, if an abnormality is detected, uses a current interrupting device such as a relay to interrupt the current flowing through the battery, thereby preventing the battery from being overcharged or overdischarged. . If such a current interrupter fails, it is not possible to prevent overvoltage or overdischarge of the battery. It is conceivable to diagnose device failures. However, in applications that require continuous power supply to the system, such as automobiles, the method of temporarily shutting off the power supply cannot be implemented.

Two current interrupters are connected in parallel, and when a certain amount of current is flowing while the vehicle is running, each current interrupter alternately opens and closes to detect changes in the voltage across the current interrupters. By using the method, it is possible to diagnose the failure of the current interrupting device while continuing to supply electric power. As a document disclosing a method for diagnosing a failure of two current interrupting devices connected in parallel, there is Patent Document 1 below, for example.

JP 2014-36556 A

However, in the above method, the failure is diagnosed by opening or closing the current interruption device while the vehicle is running. Therefore, if one of the current interrupters has an open failure due to vibrations while driving and the other current interrupter is opened for fault diagnosis, both current interrupters will be in an open state. The power supply is interrupted while driving. Moreover, the method of Patent Document 1 also has the same problem.
SUMMARY OF THE INVENTION The present invention has been completed based on the above circumstances, and it is an object of the present invention to perform failure diagnosis of a current interrupting device while avoiding interruption of power supply while a vehicle is running.

A fault diagnosis device disclosed in the present specification is a fault diagnosis device for diagnosing a fault in a pair of current interrupting devices connected in parallel and arranged in an electric path of a power storage element mounted in a vehicle. While the engine is stopped, a switching process is performed to switch one of the pair of current interrupting devices to be diagnosed from open to closed or vice versa and to close the other current interrupting device, wherein the switching process is performed. Thereafter, when a current larger than a threshold value is flowing through the current interrupting device, the voltage across the current interrupting device is detected, and based on the detected voltage across the current interrupting device, it is determined whether or not the current interrupting device is faulty.

The technology disclosed in this specification can be applied to a power storage device having the failure diagnosis device and a vehicle having the power storage device. Further, the present invention can be applied to a diagnosis method for diagnosing a failure of a current interrupting device arranged in an electric path of an electric storage device mounted on a vehicle.

According to the fault diagnosis device disclosed in this specification, it is possible to diagnose the fault of the current interrupting device while avoiding interruption of power supply while the vehicle is running.

The side view of the vehicle applied to Embodiment 1. Battery perspective view Battery exploded perspective view Block diagram showing the electrical configuration of the battery Flowchart showing the flow of failure diagnosis processing Diagram showing relay state transitions during fault diagnosis processing Graph showing waveform of cranking current at engine start Block diagram showing the electrical configuration of a battery connected to an assist motor A block diagram showing the electrical configuration of another embodiment of the battery A block diagram showing the electrical configuration of a power supply system combining a 12V system battery and a 48V system battery.

First, an overview of the failure diagnosis device disclosed in this embodiment will be described.
A fault diagnosis device for diagnosing a failure of a pair of current interrupting devices connected in parallel and arranged in an electric path of a power storage element mounted on a vehicle, wherein the pair of current interrupting devices is detected while the engine of the vehicle is stopped. A switching process is performed to switch one of the current interrupting devices to be diagnosed from open to closed or from closed to open, and to close the other current interrupting device. When the current is flowing, the voltage across the current interrupting device is detected, and based on the detected voltage across the current interrupting device, the presence or absence of failure of the current interrupting device is determined. In this configuration, switching of the current interrupting device for the purpose of fault diagnosis is performed while the engine is stopped, so the current interrupting device is not operated for the purpose of fault diagnosis while the vehicle is running. Therefore, it is possible to diagnose a failure of the current interruption device while avoiding interruption of power supply while the vehicle is running. Moreover, since the voltage across the current interrupting device is detected when a current larger than the threshold value is flowing through the current interrupting device, failure of the current interrupting device can be accurately diagnosed.

It is preferable that the voltage across the current interrupting device is detected during discharging of the storage element. When a power unit such as a motor or a compressor is connected as a load, a larger current flows during discharging than during charging, so the voltage across the fault diagnosis device can be measured with high accuracy. It is preferable that the voltage across the current interrupting device is detected during charging of the storage element. Since the current is more stable during charging than during discharging, it is easy to determine the timing of detecting the voltage across the current interrupter. Charging may be either charging by a vehicle generator such as an alternator mounted on the vehicle or charging by an external charger provided outside the vehicle.

The fault diagnosis device preferably executes the processes (1) to (3) each time the engine is stopped, thereby sequentially determining open faults and closed faults one by one for the pair of current interruption devices.
(1) Each time the engine stops, one of the pair of current interrupters to be diagnosed is alternately switched from open to closed or vice versa, and the other current interrupter is closed.
(2) detecting the voltage across the current interrupting device when a current greater than the threshold value is flowing after switching;
(3) Based on the detected voltage across both ends, it is determined whether or not there is a failure in the current interrupting device to be diagnosed.

In this configuration, out of a pair of current interrupting devices connected in parallel, one of the current interrupting devices to be diagnosed is alternately switched between open and closed to perform a fault diagnosis. Close. Therefore, there is little risk that the power supply to the vehicle will be interrupted during the diagnosis.

It is preferable to determine whether or not there is a failure in the current interrupting device to be diagnosed by comparing the voltage across the current interrupting device detected when the current greater than the threshold is flowing with the previous detected value. By comparing the detected value of this time with the detected value of the previous time, it is possible to accurately detect the presence or absence of a change in the voltage between both ends, so it is possible to accurately determine the presence or absence of a failure of the current interrupting device. Presence or absence of failure of the current interrupting device to be diagnosed by comparing the voltage across the current interrupting device detected when a current greater than the threshold is flowing with the voltage across the current interrupting device during normal operation. should be judged. By comparing the voltage across the current interrupter with that during normal operation, it is possible to determine whether the current interrupter is faulty.
The switching process may be performed while the vehicle is parked. In this configuration, since the switching process is performed while the vehicle is parked, the user does not hear the operating sound even if the operating sound occurs due to the switching.

The threshold may be set based on the peak value of the cranking current that flows when the engine is started. Since the cranking current is a large current, the change in the voltage across the current interrupting device is large. Therefore, the presence or absence of failure can be determined with high accuracy.

When the current interrupting device to be diagnosed is switched from closed to open in the switching process while the engine of the vehicle is stopped, the pair of currents connected in parallel while the vehicle is running after the voltage across both ends is detected. It is advisable to close both shut-off devices. With this configuration, for example, even if one of the current interrupting devices is unintentionally opened due to vibration or the like while the vehicle is running, electric power can be continuously supplied from the storage element to the vehicle while the vehicle is running.

When the fault diagnosis device determines that there is a fault, it is preferable to issue a warning to the vehicle. By issuing a warning, it is possible to inform the vehicle of the failure of the fault diagnosis device. The current interrupting device is preferably a relay having mechanical contacts. Since a relay is a mechanical contact, it has a larger conduction resistance when closed than a semiconductor switch such as an FET. Therefore, when the same current flows, the voltage across the switch is higher than that of the semiconductor switch, so the detection accuracy of the voltage across the switch is high. Therefore, the presence or absence of failure can be determined with high accuracy. By applying the present technology, it is possible to diagnose a failure of a current interrupting device, which has a high failure probability, while avoiding interruption of the power supply to the vehicle while the vehicle is running. The vehicle is preferably an idling stop vehicle. Cranking occurs frequently in idling stop vehicles. Therefore, there are many timings at which failure determination can be performed, and reliability is improved.

<Embodiment 1>
1. Description of Battery FIG. 1 is a side view of the vehicle, FIG. 2 is a perspective view of the battery, FIG. 3 is an exploded perspective view of the battery, and FIG. 4 is a block diagram showing the electrical configuration of the battery.

An automobile (hereinafter referred to as an example of a vehicle) 1 includes a battery (power storage device) 20 as shown in FIG. The battery 20 has a block-shaped battery case 21, as shown in FIG. . In the following description, when referring to FIGS. 2 and 3, the vertical direction of the battery case 21 when the battery case 21 is placed horizontally with respect to the installation surface without tilting is defined as the Y direction, and the long side of the battery case 21 is defined as the Y direction. The direction along the direction is defined as the X direction, and the depth direction of the battery case 21 is defined as the Z direction.

As shown in FIG. 3 , the battery case 21 includes a box-shaped case body 23 that opens upward, a positioning member 24 that positions the plurality of secondary batteries 31 , and an inner lid 25 that is attached to the top of the case body 23 . and an upper lid 26 attached to the upper portion of the inner lid 25. - 特許庁In the case main body 23, as shown in FIG. 3, a plurality of cell chambers 23A in which the secondary batteries 31 are individually accommodated are arranged side by side in the X direction.

As shown in FIG. 3 , the positioning member 24 has a plurality of bus bars 27 arranged on its upper surface, and the positioning member 24 is arranged above the plurality of secondary batteries 31 arranged in the case main body 23 . , a plurality of secondary batteries 31 are positioned and connected in series by a plurality of bus bars 27 .

As shown in FIG. 2, the inner lid 25 has a substantially rectangular shape in a plan view and has a height difference in the Y direction. A pair of terminal portions 22P and 22N are provided at both ends of the inner lid 25 in the X direction. The pair of terminal portions 22P and 22N are made of a metal such as a lead alloy, for example, 22P is a positive electrode side terminal portion and 22N is a negative electrode side terminal portion. A pair of terminal portions 22</b>P and 22</b>N are external terminals of the battery 20 .

As shown in FIG. 3, the inner lid 25 has an accommodating portion that accommodates the control board 28. By attaching the inner lid 25 to the case main body 23, the secondary battery 31 and the control board 28 are connected. It is supposed to be connected.

The electrical configuration of battery 20 will be described with reference to FIG. The battery 20 includes an assembled battery 30 , a current sensor 41 , a current cutoff circuit 45 , and a battery management device (BM) 50 that manages the assembled battery 30 . The battery management device 50 is an example of the "failure diagnosis device" of the present invention.

The assembled battery 30 is of a 12V system and is composed of a plurality of power storage elements (for example, lithium ion secondary batteries 31) connected in series. The assembled battery 30 , the current sensor 41 , and the current cutoff circuit 45 are connected in series via the energization path 35 . The current sensor 41 is arranged on the negative side, and the current interrupting circuit 45 is arranged on the positive side. The current sensor 41 is connected to the negative terminal portion 22N, and the current interrupting circuit 45 is connected to the positive terminal portion 22P.

As shown in FIG. 4, a starter motor 15 for starting an engine mounted on the vehicle 1 is connected to terminal portions 22P and 22N of the battery 20, and the starter motor 15 is supplied with electric power from the battery 20. drive. In addition to the starter motor 15, the battery 20 is connected to a vehicle load (not shown) such as electrical components and an alternator (not shown). The battery 20 is charged by the alternator when the alternator's power generation is greater than the power consumption of the vehicle load. Also, when the amount of power generated by the alternator is smaller than the power consumption of the vehicle load, the battery 20 discharges to make up for the shortage.

The current sensor 41 is provided inside the battery case 21 and detects the current I flowing through the secondary battery 31 . The current sensor 41 is electrically connected to the BM 50 via a signal line, and the output of the current sensor 41 is taken into the BM 50 .

The current cutoff circuit 45 is provided inside the battery case 21 . The current interrupting circuit 45 is arranged on the conducting path 35 of the assembled battery 30 and is composed of a pair of relays RL1 and RL2 connected in parallel. The reason why the two relays RL1 and RL2 are provided in parallel is to ensure redundancy so that power supply to the vehicle can be maintained even if one of the relays RL1 and RL2 fails. The relays RL1 and RL2 are examples of current interrupters.

The relays RL1 and RL2 are, for example, latch type relays, and mechanically open their contacts by electromagnetic action when receiving an open command from the BM50. Also, when receiving a close command, the contacts are mechanically closed by electromagnetic action.

The BM 50 can individually control the opening and closing of the relays RL1 and RL2 by individually sending open instructions and close instructions to the relays RL1 and RL2. By closing at least one of the two relays RL1 and RL2, the assembled battery 30 becomes energized. Also, by opening both the two relays RL1 and RL2, the power supply to the battery pack 30 is cut off. In the following description, the symbol RL is used when the two relays are not particularly distinguished.

The BM 50 includes a CPU 51 having an arithmetic function, a memory 53 storing various information, a communication section 55 and the like, and is provided on the control board 28 . A vehicle ECU (Electronic Control Unit) 10 mounted on the vehicle is connected to the communication unit 55 , and the BM 50 can receive information about the vehicle such as the operating state of the engine from the vehicle ECU 10 . ing.

BM 50 monitors the current of secondary battery 31 based on the output of current sensor 41 . The voltage of each secondary battery 31 and the total voltage of the assembled battery 30 are monitored based on the output of a voltage detection circuit (not shown). The temperature of the secondary battery 31 is monitored based on the output of a temperature sensor (not shown).

The BM 50 monitors the voltage, current, and abnormality of the secondary battery 31, and when detecting an abnormality, opens the two relays RL1 and RL2 to prevent the secondary battery 31 from entering a dangerous state. prevent.

The BM50 is connected to both ends of the relays RL1 and RL2 and to the end point A and the end point B by voltage measurement lines La and Lb, respectively, and detects the voltage across the relays RL1 and RL2 (voltage between two points AB) Vab. do.

2. Fault Diagnosis of Relays RL1 and RL2 The CPU 51 of the BM 50 switches the relay RL from open to closed or from closed to open while the vehicle is parked, and then detects the voltage Vab across the relay RL when the engine is started. Then, the CPU 51 diagnoses open failure and closed failure of the relay RL based on the detected both-end voltage Vab. An open failure is a failure that does not close and remains open even after receiving a close command. A closed failure is a failure in which even if an open command is received, it does not open and is stuck in the closed state.

The failure diagnosis processing of the relay RL will be specifically described below with reference to FIGS. 5 and 6. FIG. The failure diagnosis process shown in FIG. 5 is composed of steps S10 to S50, and is executed by the CPU 51 at the same time when the BM 50 is activated and starts monitoring the assembled battery 30, for example.

It is assumed that both the relay RL1 and the relay RL2 are in the closed state before the failure diagnosis processing. It is assumed that the failure diagnosis of the relay RL1 is performed in the first and second failure diagnosis processes, and the failure diagnosis of the relay RL2 is performed in the third and fourth failure diagnosis processes.

<First time (failure diagnosis of relay RL1)>
When the process starts, the BM 50 executes a process of detecting parking of the vehicle (S10). Parking is a state in which at least a drive unit such as an engine or a motor is stopped and the vehicle does not move for a predetermined time. Whether or not the vehicle is parked can be determined by determining whether or not the current value detected by the current sensor 41 has remained below a predetermined value for a predetermined time or longer. The predetermined value is set according to the amount of dark current (microcurrent) that flows only from the battery 20 to a specific load of the vehicle while the vehicle is parked, and is, for example, about 100 mA. In addition to this, for example, it is possible to determine whether or not communication with the vehicle ECU 10 has been stopped for a predetermined time or longer.

When the parking of the vehicle (first parking) is detected, the BM 50 next performs a process of switching between open and closed of one of the two relays RL1 and RL2 to be diagnosed, RL1 (S20).

In the process of S20 executed for the first time, an open command is transmitted from the BM 50 to the relay RL1. As a result, as shown in FIG. 6A, the relay RL1 is switched from closed to open if normal. No command is sent from BM 50 to relay RL2, and relay RL2 remains closed.

After switching the relay RL1, the BM 50 next executes a process of detecting the start of the engine (S30). Start of the engine can be detected based on whether the current value detected by the current sensor 41 is greater than a threshold value. The threshold value is set according to the magnitude of the peak value Ip of the cranking current flowing from the battery 20 to the starter motor 15 when the engine is cranked, and is about 800 A as an example.

During the period until the start of the engine is detected, the process of S30 is repeated to enter a standby state. When the engine start is detected, the BM 50 detects the voltage Vab across the pair of relays RL1 and RL2 (S40). Specifically, as shown in FIG. 7, the voltage Vab to detect

Assuming that the conduction resistance value (resistance value in the closed state) per relay is 200 μΩ, the resistance value between the two points AB is 200 μΩ when the relay RL1 is normally open. Therefore, if the relay RL1 is normally opened, the detected both-ends voltage Vab is 160 mV.

After detecting the voltage Vab across the terminals, the BM 50 next compares the voltage Vab across the terminals detected in S40 with the previous value to obtain a voltage difference, thereby executing a process of determining whether or not the relay RL1 is faulty. In the first determination, since the previous value does not exist, the relay RL1 failure determination is not performed, and the process of storing the voltage Vab detected in S40 in the memory 53 is performed. Thus, the first failure diagnosis process (S10-S50) is completed.

<Second time (failure diagnosis of relay RL1)>
After that, the second process is started, and the BM 50 executes the process of detecting parking of the vehicle (S10). After the engine is started, while the vehicle is running, the process of S10 (S10: NO) is repeated to enter a standby state.

When the vehicle shifts from running to parking (second parking), the BM 50 detects that the vehicle is parked, and performs processing for switching relay RL1 between open and closed (S20).

In the process of S20 executed for the second time, a close command is transmitted from the BM 50 to the relay RL1. As a result, as shown in FIG. 6B, the relay RL1 is switched from open to closed if normal. No command is sent from BM 50 to relay RL2, and relay RL2 remains closed.

After sending the switching command to the relay RL1, the BM 50 next executes a process of detecting the start of the engine (S30). During the period until the start of the engine is detected, the process of S30 is repeated to enter a standby state.

When the engine start is detected, the BM 50 detects the voltage Vab across the pair of relays RL1 and RL2 (S40). Assuming that the conduction resistance value for each relay is 200 μΩ, the resistance value between the two points AB is 100 μΩ when the relay RL1 operates normally and is closed. Therefore, when the relay RL1 is normally closed, the voltage Vab across the terminals detected when the engine is started is 80 mV.

After detecting the voltage Vab across the terminals, the BM 50 next executes a process of determining whether or not the relay RL1 is faulty based on the voltage Vab across the terminals detected in S40. Specifically, if the relay RL1 operates normally and is closed, the second detected voltage Vab is 80 mV, which is approximately 80 mV higher than the first detected voltage Vab. there is a difference.

Therefore, the voltage Vab detected in S40 is compared with the previous value, and if the absolute value of the voltage difference between the two voltages Vab is equal to or greater than a specified value (40 mV as an example), it is determined that the relay RL1 does not have an open failure. can.

If it is determined that there is no open failure, the process of storing the voltage Vab detected in S40 in the memory 53 is performed. Thus, the second failure diagnosis process (S10-S50) is completed. After that, the third failure diagnosis process is executed.

In the second failure diagnosis process, if the absolute value of the voltage difference between the two end-to-end voltages Vab is less than a specified value (eg, 40 mV), it is determined that the relay RL1 has an open failure. When it is determined that there is an open failure, warning processing such as notifying the vehicle ECU 10 of the abnormality from the BM 50 is executed.

<Third time (failure diagnosis of relay RL2)>
After that, the third process is started, and the BM 50 executes the process of detecting parking of the vehicle (S10). When the vehicle shifts from running to parking (third parking), the BM 50 detects that the vehicle is parked, and performs processing for switching relay RL2 between open and closed (S20).

In the process of S20 executed for the third time, an open command is transmitted from the BM 50 to the relay RL2. As a result, as shown in FIG. 6C, the relay RL2 is switched from closed to open if normal. No command is sent from BM 50 to relay RL1, and relay RL1 remains closed.

After sending the switching command to the relay RL2, the BM 50 next executes a process of detecting the start of the engine (S30). During the period until the start of the engine is detected, the process of S30 is repeated to enter a standby state.

When the engine start is detected, the BM 50 detects the voltage Vab across the pair of relays RL1 and RL2 (S40). When the relay RL2 operates normally and is open, the resistance value between the two points AB is 200 μΩ. Therefore, when the relay RL2 operates normally and is open, the voltage Vab across the terminals detected when the engine is started is 160 mV.

After detecting the voltage Vab across the terminals, the BM 50 next executes a process of determining whether or not the relay RL2 is faulty based on the voltage Vab across the terminals detected in S40. Specifically, if the relay RL2 operates normally and is open, the voltage across the terminals Vab detected for the third time is 160 mV, which is a voltage difference of about 80 mV from the voltage across the terminals Vab detected the second time. occurs.

Therefore, the voltage Vab detected in S40 is compared with the previous value, and if the absolute value of the voltage difference between the two voltages Vab is equal to or greater than a specified value (40 mV as an example), it is determined that the relay RL2 is not closed. can.

If it is determined that there is no closing failure, the process of storing the voltage Vab detected in S40 in the memory 53 is performed. Thus, the third failure diagnosis process (S10-S50) is completed. After that, the fourth failure diagnosis process is executed.

In the third failure diagnosis process, if the absolute value of the voltage difference between the two end-to-end voltages Vab is less than a specified value (eg, 40 mV), it is determined that the relay RL2 has a closed failure. When it is determined that there is a closed failure, warning processing such as notifying the vehicle ECU 10 of the abnormality from the BM 50 is executed.

<Fourth time (failure diagnosis of relay RL2)>
After that, the fourth process is started, and the BM 50 executes the process of detecting parking of the vehicle (S10). When the vehicle shifts from running to parking (fourth parking), the BM 50 detects that the vehicle is parked, and performs processing for switching relay RL2 between open and closed (S20).

In the process of S20 executed for the fourth time, a close command is transmitted from the BM 50 to the relay RL2. As a result, as shown in FIG. 6D, the relay RL2 is switched from open to closed if normal. No command is sent from BM 50 to relay RL1, and relay RL1 remains closed.

After sending the switching command to the relay RL2, the BM 50 next executes a process of detecting the start of the engine (S30). During the period until the start of the engine is detected, the process of S30 is repeated to enter a standby state.

When the engine start is detected, the BM 50 detects the voltage Vab across the pair of relays RL1 and RL2 (S40). When the relay RL2 operates normally and is closed, the resistance between the two points AB is 100 μΩ. Therefore, when the relay RL2 operates normally and is closed, the voltage Vab across the terminals detected when the engine is started is 80 mV.

After detecting the voltage Vab across the terminals, the BM 50 next executes a process of determining whether or not the relay RL2 is faulty based on the voltage Vab across the terminals detected in S40. Specifically, if the relay RL2 is normal, the fourth detected voltage Vab is 80 mV, and there is a voltage difference of about 80 mV from the third detected voltage Vab.

Therefore, the voltage Vab detected in S40 is compared with the previous value, and if the absolute value of the voltage difference between the two voltages Vab is equal to or greater than a specified value (40 mV as an example), it is determined that the relay RL2 does not have an open failure. can. If it is determined that there is no open failure, the process of storing the voltage Vab detected in S40 in the memory 53 is performed. Thus, the fourth failure diagnosis process (S10-S50) is completed.

In the fourth failure diagnosis process, if the absolute value of the voltage difference between the two end-to-end voltages Vab is less than a specified value (eg, 40 mV), it is determined that the relay RL2 has an open failure. When it is determined that there is an open failure, warning processing such as notifying the vehicle ECU 10 of the abnormality from the BM 50 is executed.

The first to fourth failure diagnosis processing constitutes one cycle. When the first cycle ends, the second cycle starts, and the first failure diagnosis process is executed in sequence in the same manner as in the first cycle.

Thus, in the first failure diagnosis process, after sending a command to open the relay RL1 while the vehicle is parked, the BM detects the voltage Vab across the pair of relays RL1 and RL2 when the engine is started.

Comparing the detected both-ends voltage Vab with the previous value (the both-ends voltage Vab detected in the fourth failure diagnosis process of the first cycle) to obtain a voltage difference, and comparing the absolute value of the obtained voltage difference with a specified value. Accordingly, the BM 50 determines whether the relay RL1 has a closing failure.

If it is determined that there is no closing failure, the process of storing the voltage Vab detected in S40 in the memory 53 is performed. On the other hand, when it is determined that there is a closing failure, warning processing such as notifying the vehicle ECU 10 of the abnormality from the BM 50 is executed.

The failure diagnosis process from the second time onward is the same as the failure diagnosis process of each time in the first cycle, and in the second failure diagnosis process, it is determined whether the relay RL1 has an open failure. In the third failure diagnosis process, it is determined whether the relay RL2 has a closing failure. In the fourth failure diagnosis process, it is determined whether the relay RL2 has an open failure.

As described above, each time the vehicle is parked, the BM 50 executes the following (1) to (3), thereby sequentially diagnosing the pair of relays RL1 and RL2 for an open failure and a closed failure. .

(1) Parking of the vehicle is detected, one of the pair of relays RL1 and RL2 to be diagnosed is alternately switched from open to closed or closed to open, and the other relay is closed (S20).
(2) After switching, when the engine is started, the voltage Vab across the relays RL1 and RL2 is detected (S40).
(3) Based on the detected both-ends voltage Vab, it is determined whether or not there is a failure in the relay RL to be diagnosed (S50).

3. Explanation of Effect In this configuration, switching of the relays RL1 and RL2 for the purpose of fault diagnosis is performed while the vehicle is parked, so the relays RL1 and RL2 are not operated for the purpose of fault diagnosis while the vehicle is running. Therefore, it is possible to diagnose the failure of the relays RL1 and RL2 while avoiding interruption of power supply while the vehicle is running. Therefore, it is possible to meet the requirements of functional safety (ISO26262 standard) required for automobiles.

Further, when the cranking current for starting the engine flows, the voltage Vab across the relays RL1 and RL2 is detected. Since the cranking current is a large current, the change in the both-ends voltage Vab is large. Therefore, it is possible to accurately determine whether or not the relays RL1 and RL2 have failed.

In this configuration, since the failure diagnosis is performed by alternately switching between open and closed of the pair of relays RL1 and RL2, one of the relays RL1 and RL2 is in the closed state even during the failure diagnosis. Therefore, even during the failure diagnosis, the risk of power supply to the vehicle being interrupted is small.

<Embodiment 2>
In the first embodiment, the BM 50 switches the relays RL1 and RL2 to be diagnosed from closed to open during parking in order to diagnose the closed failure of the relays RL1 and RL2. For example, in FIG. 6A, the relay RL1 is switched from closed to open when parking is detected in order to diagnose the closed failure of the relay RL1, and in FIG. 6C, the closed failure of the relay RL2 is diagnosed. Therefore, when parking is detected, the relay RL2 is switched from closed to open.

After switching the relays RL1 and RL2, when the engine is started, the voltage Vab across the relays RL1 and RL2 is detected and compared with the previous value to diagnose an open failure of the relays RL1 and RL2.

In the second embodiment, the BM 50 closes both the pair of relays RL1 and RL2 connected in parallel while the vehicle is running after the voltage across both ends is detected. Specifically, as shown in FIG. 6A, after switching the relay RL1 to open and diagnosing a closed failure of the relay RL1, when the vehicle shifts to the running state, the BM 50 closes the relay RL1. send a command for This causes relay RL1 to switch from open to closed, and both relays RL1 and RL2 are closed during running.

Further, as shown in FIG. 6C, after switching the relay RL2 to open and diagnosing a closed failure of the relay RL2, when the vehicle shifts to the running state, the BM 50 issues a close command to the relay RL2. send. This causes relay RL2 to switch from open to closed, and both relays RL1 and RL2 are closed during running.

The vehicle ECU 10 monitors the state of the engine. Therefore, the BM 50 can determine whether the vehicle 1 is running or not by receiving information about the state of the engine from the vehicle ECU 10 through communication.

In the second embodiment, by closing both of the two relays RL1 and RL2 while driving, for example, one of the pair of relays RL1 and RL2 may be unintentionally activated due to vibration or the like during driving. Even when the door is open to the full, the power supply from the battery 20 to the vehicle can be continued while the vehicle is running. Therefore, it is possible to meet the requirements of functional safety (ISO26262 standard) required for automobiles. In the second embodiment, both of the two relays RL1 and RL2 are closed while the vehicle is running. Therefore, as shown in FIGS. 6B and 6D, when diagnosing an open failure of the relays RL1 and RL2, there is no need to close the relays RL1 and RL2 again while the vehicle is parked. Occasionally, by detecting the voltage Vab across the relay RL and comparing it with the previous value, it is possible to diagnose the presence or absence of an open fault in the relays RL1 and RL2.

<Other embodiments>
The present invention is not limited to the embodiments explained by the above description and drawings, and for example, the following embodiments are also included in the technical scope of the present invention.

(1) In Embodiments 1 and 2, the relay RL was exemplified as an example of the current interrupting device, but a semiconductor switch such as an FET or a transistor may also be used. Moreover, although the lithium ion secondary battery is illustrated as an example of the storage element, the storage element may be another secondary battery, capacitor, or the like. The number of power storage elements does not need to be plural, and may be one.

(2) In Embodiments 1 and 2, an example was shown in which the switching process for switching the diagnosis target relay RL from open to closed or from closed to open was performed while the vehicle was parked. The execution timing of the switching process is not limited to when the vehicle is parked, and may be executed at any time as long as the engine is stopped. For example, it may be performed immediately after the engine is stopped.

(3) In the above embodiments 1 and 2, the relay RL is switched when the vehicle is parked, and then the voltage Vab across the relay RL detected when the engine is started is compared with the previous value to detect the failure of the relay RL. A method for determining the presence/absence is exemplified. Determination of the presence or absence of failure of the relay RL can be performed in addition to the method exemplified in the embodiment. The presence or absence of a failure may be determined by comparing with the voltage between both ends (Vab) detected when the engine is started. For example, as shown in FIG. 6B, when diagnosing an open failure of the relay RL1 by switching the relay RL1 to a closed state, if the relay RL1 does not have an open failure, the relay RL detected when the engine is started The voltage Vab across the terminal is 80 mV. Therefore, the presence or absence of a failure may be determined based on whether or not the voltage Vab that is actually detected is 80 mV.

(4) In the above embodiments 1 and 2, the relay RL is switched when the vehicle is parked, and then the voltage Vab across the relay RL detected when the engine is started is compared with the previous value to detect the failure of the relay RL. A method for determining the presence/absence is exemplified. The timing for detecting the voltage Vab across the relay RL may be when the engine is started after idling stop. That is, when the engine is started a plurality of times after detecting parking and switching the relay RL until the next parking of the vehicle, the voltage Vab across the relay RL may be detected at any timing. Idling stop is a system that automatically turns off the engine when the vehicle is stopped such as waiting at a traffic light, and restarts the engine when the vehicle starts moving.

(5) In the first and second embodiments, the relay RL is switched from open to closed or from closed to open while the vehicle is parked. After that, when a current of 800 A or more was flowing through the relay RL, the voltage Vab across the relay RL was detected, and open failure and close failure of the relay RL were diagnosed based on the detected voltage Vab across the relay RL. The current threshold that determines whether or not the voltage Vab can be detected is not limited to 800A. For example, if the conduction resistance of each relay RL is 800 μΩ and the minimum voltage that can be measured by the BM50 is 80 mV, when a current of 200 A or more flows, the voltage Vab across the two relays RL1 and RL2 when they are closed is 80 mV equals the lowest voltage that BM50 can measure. Therefore, the voltage Vab across the relay RL can be detected when a current of 200 A or more is flowing, with a threshold value of 200 A. In addition, when the conduction resistance of each relay RL is 800 μΩ and the minimum voltage measurable by BM50 is 40 mV, if a current of 100 A or more is flowing, the voltage across the two relays RL1 and RL2 when closed is Vab is 40 mV, equal to the lowest voltage that BM50 can measure. Therefore, the voltage Vab across the relay RL can be detected when a current of 100 A or more is flowing, with a threshold value of 100 A. As described above, the threshold can be determined based on whether the voltage Vab across the relay RL can be measured by the BM50.

Further, when a current larger than the threshold value is flowing through the relay RL, the voltage Vab across the relay RL can be detected at a timing other than when the engine is started, for example, when the vehicle 1 starts running or during running. good. As shown in FIG. 8, when the assist motor 16 for assisting the running of the vehicle 1 is connected to the battery 20, the relay RL may be detected. The current value to be compared with the threshold value is the total current flowing through the two relays RL1 and RL2. Current flowing, if both relays RL1 and RL2 are closed, is the sum of the currents flowing in the two closed relays RL1 and RL2.

(6) The timing of detecting the voltage Vab across the relay RL may be any time when a current larger than the threshold value is flowing through the relay RL, and may be during discharging or during charging. When a power device such as a motor or a compressor is connected to the battery 20 as a load, a larger current flows during discharging than during charging. Therefore, the voltage Vab across the relay RL is high, and measurement accuracy is high. . Therefore, when the measurement accuracy is given priority, it is preferable to detect the both-ends voltage Vab while the battery 20 is being discharged. During charging, the current is often more stable than during discharging, and the timing of detecting the voltage Vab across the relay RL is easy. Therefore, when priority is given to the detection timing, it is preferable to detect the both-ends voltage Vab while the battery 20 is being charged. Charging may be either charging by a vehicle generator such as an alternator mounted on the vehicle or charging by an external charger provided outside the vehicle. Whether the battery 20 is being discharged or being charged can be determined by the CPU 51 based on the polarity of the current detected by the current sensor 41 .

(7) In Embodiments 1 and 2, the current cutoff circuit 45 is composed of two relays RL1 and RL2 connected in parallel. As in the battery 100 shown in FIG. 9, the current cutoff circuit 145 may have a configuration in which a semiconductor switch 145A and a relay 145B are combined in parallel. If the current capacity of the semiconductor switch 145A is smaller than the current capacity of the relay 145B, a plurality of semiconductor switches 145A may be connected in parallel to compensate for the lack of current capacity.

(8) In Embodiments 1 and 2, the power supply system that supplies power to the starter motor 15 from the 12V system assembled battery 30 is exemplified. As shown in FIG. 10, the present technology transfers a 12V vehicle load U such as a cell motor and an assist motor from a battery system 200 that combines a 48V system battery 250 via a DC-DC converter 230 to a 12V system battery 210. On the other hand, it can be applied to the power supply system 200 that supplies electric power. Moreover, it can be applied to a power supply system in which a 12V system assembled battery and a 24V system assembled battery are combined.

(10) In addition, the technology disclosed in this specification can be applied to applications in which a current equal to or greater than a threshold flows through the current interrupting device. The batteries 20 and 100 and the power supply system 200 may be installed in HEVs (Hybrid Electric Vehicles), two-wheeled vehicles, railroad vehicles that generate a large amount of regenerative power, and the like, without being limited to automobiles as described above. When the present technology is applied to the batteries 20, 100 and the power supply system 200 mounted on an idling stop vehicle, cranking occurs frequently, so there are many timings at which failure detection can be performed, and the reliability of failure detection is improved. .

1... Automobile (an example of the "vehicle" of the present invention)
15... Starter motor 20... Battery (an example of the "power storage device" of the present invention)
30... Assembled battery 31... Secondary battery (an example of the "storage element" of the present invention)
41...Current sensor 45...Current interruption circuit 50...Battery management device (an example of the "failure diagnosis device" of the present invention)
RL1...Relay (an example of the "current interrupter" of the present invention)
RL2...Relay (an example of the "current interrupter" of the present invention)

Claims (16)

Diagnosing the failure of the first current interrupting device of a pair of current interrupting devices consisting of a first current interrupting device and a second current interrupting device arranged in an electricity path of a storage element mounted in a vehicle and connected in parallel. A fault diagnosis device that
performing a first switching process of switching the first current interrupting device from open to closed or vice versa and closing the second current interrupting device while the engine of the vehicle is stopped;
After the first switching process, when a current larger than a threshold value is flowing through the second current interrupting device, the voltage across the pair of current interrupting devices is detected, and the first current is detected based on the detected voltage across the current interrupting device. A failure diagnosis device that determines whether or not there is a failure in the disconnecting device. The failure diagnosis device according to claim 1,
After the failure determination of the first current interrupting device, the second current interrupting device is switched from open to closed or from closed to open while the engine of the vehicle is stopped, and the first current interrupting device whose failure has been determined is closed. 2 Perform switching processing,
After the second switching process, when a current larger than a threshold value is flowing through the first current interrupting device that has been determined to be faulty , the voltage across the current interrupting device is detected, and based on the detected voltage across the first current interrupting device, the 2 A fault diagnosis device that determines whether or not there is a fault in the current interrupter. The fault diagnosis device according to claim 1 or claim 2 ,
A fault diagnosis device that detects the voltage across the current interrupting device while the storage element is discharging. The fault diagnosis device according to claim 1 or claim 2 ,
A fault diagnosis device that detects the voltage across the current interrupting device while the storage element is being charged. The fault diagnosis device according to any one of claims 1 to 4 ,
The second switching process switches the second current interrupting device from open to closed or from closed to open while the engine of the vehicle is stopped after failure determination of the first current interrupting device, and switching the first current interrupting device, which has already been determined to be failure, to open. It is a process of closing the blocking device,
A fault diagnosis device that executes the first switching process or the second switching process while the vehicle is parked. The fault diagnosis device according to any one of claims 1 to 5 ,
The failure diagnosis device, wherein the threshold value is set based on a peak value of cranking current that flows when the engine is started. The fault diagnosis device according to any one of claims 1 to 6 ,
The fault diagnosis device executes the processes (1) to (3) four times as one cycle each time the engine stops,
In the first and second processes, open failure and closed failure are determined for one current interrupting device, and in the third and fourth processes, open failure and closed failure are determined for the other current interrupting device.
A fault diagnosis device for sequentially determining open faults and closed faults one by one for the pair of current interrupting devices.
(1) Each time the engine stops, one of the pair of current interrupters to be diagnosed is alternately switched from open to closed or vice versa, and the other current interrupter is closed.
(2) After switching, detecting the voltage across the current interrupting device when a current having a current value larger than the threshold value is flowing.
(3) Based on the detected voltage across both ends, it is determined whether or not there is a failure in the current interrupting device to be diagnosed. The fault diagnosis device according to claim 7 ,
Failure diagnosis for determining whether or not there is a failure in the current interrupting device to be diagnosed by comparing the voltage across the current interrupting device detected when a current greater than the threshold is flowing with the previously detected value. Device. The fault diagnosis device according to claim 7 ,
By comparing the voltage across the current interrupting device detected when a current greater than the threshold is flowing with the voltage across the current interrupting device during normal operation, the failure of the current interrupting device to be diagnosed is determined. Fault diagnosis device for determining presence/absence. The fault diagnosis device according to any one of claims 1 to 9 ,
The second switching process switches the second current interrupting device from open to closed or from closed to open while the engine of the vehicle is stopped after failure determination of the first current interrupting device, and switching the first current interrupting device, which has already been determined to be failure, to open. It is a process of closing the blocking device,
When the current interrupting device to be diagnosed is switched from closed to open in the first switching process or the second switching process while the engine of the vehicle is stopped,
A fault diagnosis device that closes both of the pair of current interrupters connected in parallel while the vehicle is running after the voltage across the terminals is detected. The fault diagnosis device according to any one of claims 1 to 10 ,
A fault diagnosis device that issues a warning to the vehicle when the current interruption device determines that there is a fault. The fault diagnosis device according to any one of claims 1 to 11 ,
The fault diagnosis device, wherein the current interrupting device is a relay having a mechanical contact. The fault diagnosis device according to any one of claims 1 to 12 ,
The failure diagnosis device, wherein the power storage element is a lithium ion secondary battery. The fault diagnosis device according to any one of claims 1 to 13 ,
The fault diagnosis device, wherein the vehicle is an idling stop vehicle. a storage element;
a fault diagnosis device according to any one of claims 1 to 14 ;
A power storage device including a case that accommodates the power storage element and the fault diagnosis device. A failure diagnosis method for diagnosing a failure of a pair of current interrupting devices connected in parallel and arranged in an electric path of a power storage element mounted on a vehicle,
While the engine of the vehicle is stopped, a first switching process is performed to switch one of the pair of current interrupting devices to be diagnosed from open to closed or vice versa and to close the other current interrupting device. ,
After the first switching process, a voltage across the current interrupting device is detected when a current larger than a threshold value is flowing through the current interrupting device, and failure of one of the current interrupting devices is detected based on the detected voltage across the current interrupting device. determine the presence or absence of
a second switching process of switching the other current interrupting device to be diagnosed among the pair of current interrupting devices from open to closed or vice versa and closing one of the current interrupting devices while the engine of the vehicle is stopped; do,
After the second switching process, when a current larger than a threshold value is flowing through the current interrupting device, a voltage across the current interrupting device is detected, and based on the detected voltage across the current interrupting device, failure of the other current interrupting device is detected. A failure diagnosis method for determining the presence or absence of

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