Power supply

Abstract

To suppress occurrence of inrush current when attaching a terminal of an electric power unit to an auxiliary machinery.SOLUTION: An electric power unit mounted on a vehicle to supply an auxiliary machinery with electric power comprises: a battery; a terminal which is connected to the auxiliary machinery; a current sensor which detects discharge current of the battery; a main circuit which includes a main relay and connects through the main relay between the battery and the terminal; a bypass circuit which includes a sub relay, bypasses through the sub relay the main relay and has a high resistance value compared with the main circuit; a processing circuit which controls the main relay and the sub relay based on a detection current value by the current sensor. The processing circuit turns off, when the detection current value is a first specified value or less during parking of the vehicle, the main relay and turns on the sub relay.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a power supply device that supplies power to auxiliary equipment mounted on a vehicle. [Background technology]

[0002] Patent Document 1 describes a power supply device that supplies power to an auxiliary device mounted on a vehicle. This power supply device includes a battery, a terminal connected to the auxiliary device, a main circuit that connects between the battery and the terminal via a main relay, and a processing circuit that controls the main relay. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-199099 A Summary of the Invention [Problem to be solved by the invention]

[0004] Some of the auxiliary devices mounted on a vehicle are supplied with power from a battery even while the vehicle is parked. Therefore, if the vehicle is left unused for a long period of time, the voltage of the battery may drop, causing the battery to run out. In order to avoid such a situation, it is possible to electrically disconnect the terminals of the power supply device from the auxiliary devices before the vehicle is left unused for a long period of time. On the other hand, in recent years, lithium ion batteries are sometimes used as batteries instead of lead-acid batteries. The internal resistance of a lithium ion battery is significantly smaller than that of a lead-acid battery. Therefore, when a lithium ion battery is used as a battery instead of a lead-acid battery, if the terminals of the power supply device are electrically disconnected from the auxiliary devices and then reattached to the auxiliary devices, a sudden large current (so-called inrush current) may be generated, which may affect the auxiliary devices. Such a problem is not limited to a specific battery such as a lithium ion battery, and may occur similarly even when a battery with a relatively small internal resistance is used.

[0005] In consideration of the above circumstances, this specification provides a technique for suppressing the occurrence of inrush current when a terminal of a power supply device is attached to an auxiliary device. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a power supply device that supplies power to an auxiliary device mounted on a vehicle. The power supply device includes a battery, a terminal connected to the auxiliary device, a current sensor that detects a discharge current of the battery, a main circuit having a main relay and connecting the battery and the terminal via the main relay, a bypass circuit having a sub-relay that bypasses the main relay via the sub-relay and has a higher resistance than the main circuit, and a processing circuit that controls the main relay and the sub-relay based on a current value detected by the current sensor. The processing circuit is configured to turn off the main relay and turn on the sub-relay when the detected current value becomes equal to or less than a first predetermined value while the vehicle is parked.

[0007] For example, suppose that the terminals of the power supply device are electrically disconnected from the auxiliary equipment to prevent the battery from running out due to the vehicle being left unused for a long period of time. In this case, the supply of power from the power supply device to the auxiliary equipment is stopped, and the discharge current of the battery decreases. When the current value detected by the current sensor becomes equal to or less than a first predetermined value, the processing circuit turns off the main relay and turns on the sub-relay. Thereby, when the terminals of the power supply device are subsequently reattached to the auxiliary equipment, the battery and the auxiliary equipment are connected via a bypass circuit having a relatively high resistance. As a result, it is possible to suppress the generation of an inrush current when the terminals of the power supply device are attached to the auxiliary equipment. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle 100 and a power supply device 10. [Diagram 2]4 is a flow diagram showing a series of processes executed by the processing circuit 18 of the power supply device 10. [Diagram 3] 3 is a diagram showing an example of current values ​​detected by the current sensor 16 corresponding to changes in the state of the vehicle 100, the state of attachment of the terminal 14 of the power supply device 10 to the auxiliary device 102, and the on / off states of the main relay 22 and the sub-relay 26. Note that period E1 in Fig. 3 corresponds to the period immediately after the terminal 14 of the power supply device 10 is attached to the auxiliary device 102. The dotted line in period E1 in Fig. 3 indicates, as a comparative example, a case in which the battery 12 and the auxiliary device 102 are connected via the main circuit 20. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one embodiment of the present technology, the processing circuit may be configured to turn on the main relay and turn on the sub-relay when the detected current value becomes equal to or greater than a second predetermined value after turning off the main relay and turning on the sub-relay. With this configuration, after the inrush current is suppressed by the bypass circuit, power can be supplied from the battery to the auxiliary through the main circuit with a relatively low resistance. This makes it possible to prevent a portion of the power supplied from the battery to the auxiliary from being consumed by the high resistance of the bypass circuit. EXAMPLES

[0010] With reference to the drawings, a power supply device 10 according to an embodiment and a vehicle 100 in which the power supply device 10 is employed will be described. The power supply device 10 is a device that supplies power to an auxiliary device 102 mounted on the vehicle 100. The vehicle 100 referred to here is a so-called automobile, which is a vehicle that runs on a road surface. Here, the road surface is not limited to a so-called public road, but also includes private land and an indoor floor surface on which the vehicle 100 can run. Furthermore, the technology described in this embodiment is not limited to vehicles that run on a road surface, and can also be effectively adopted for vehicles that run on a track. The vehicle 100 is, for example, an engine vehicle, a hybrid vehicle, a fuel cell vehicle, an electric vehicle, a solar car, etc. Furthermore, the technology disclosed in this embodiment is not limited to the vehicle 100, but can be adopted in moving bodies such as ships and aircraft.

[0011] As shown in FIG. 1, the power supply device 10 includes a battery 12 and a terminal 14. The battery 12 is a secondary battery in which a plurality of battery cells are connected in series. The terminal 14 is provided exposed from the housing of the power supply device 10, and can be attached to the auxiliary device 102. When the terminal 14 is attached to the auxiliary device 102, the battery 12 and the auxiliary device 102 are electrically connected via the terminal 14 (and at least one of a main circuit 20 or a bypass circuit 24 described later). This allows the battery 12 to supply power to the auxiliary device 102, and the auxiliary device 102 can operate using the power. The auxiliary device 102 is, for example, a room lamp or a car navigation device. In addition, the specific number of the plurality of battery cells included in the battery 12 is not particularly limited, and may be at least one. Each of the plurality of battery cells is, for example, a lithium ion battery. However, each of the plurality of battery cells does not necessarily have to be a lithium ion battery, and may be another battery such as a nickel-metal hydride battery.

[0012] As shown in Fig. 1, the power supply device 10 further includes a current sensor 16 and a processing circuit 18. The current sensor 16 is connected in series with the battery 12 and can detect the current of the battery 12. The processing circuit 18 is communicatively connected to the current sensor 16 and can monitor the current of the battery 12 detected by the current sensor 16. The processing circuit 18 is configured to be always operable by power supplied from the battery 12, regardless of the state of the main switch of the vehicle 100. Therefore, the processing circuit 18 can monitor the current of the battery 12 even when the vehicle 100 is parked.

[0013] As shown in Fig. 1, the power supply device 10 further includes a main circuit 20. The main circuit 20 has a main relay 22. The main relay 22 is disposed between the battery 12 and the terminal 14, and can electrically connect and disconnect between the battery 12 and the auxiliary device 102 connected via the terminal 14. The on and off of the main relay 22 is controlled by the processing circuit 18. When the main relay 22 is turned on, the battery 12 and the auxiliary device 102 are electrically connected, and when the main relay 22 is turned off, the battery 12 and the auxiliary device 102 are electrically disconnected.

[0014] As shown in FIG. 1, the power supply device 10 further includes a bypass circuit 24. The bypass circuit 24 includes a sub-relay 26 and a resistor 28, and the sub-relay 26 and the resistor 28 are connected in series. Therefore, the bypass circuit 24 has a higher resistance than the main circuit 20. The bypass circuit 24 is disposed between the battery 12 and the terminal 14 and in parallel with the main circuit 20. That is, the bypass circuit 24 bypasses the main relay 22 via the sub-relay 26. Like the main relay 22, the sub-relay 26 can electrically connect and disconnect between the battery 12 and the auxiliary device 102 connected via the terminal 14. The on and off of the sub-relay 26 is controlled by the processing circuit 18. When the sub-relay 26 is turned on, the battery 12 and the auxiliary device 102 are electrically connected, and when the sub-relay 26 is turned off, the battery 12 and the auxiliary device 102 are electrically disconnected.

[0015] As described above, the on / off of the main relay 22 and the on / off of the sub-relay 26 are both controlled by the processing circuit 18. Therefore, the processing circuit 18 can switch between a state in which the battery 12 and the auxiliary device 102 are connected via the main circuit 20 and a state in which the battery 12 and the auxiliary device 102 are connected via the bypass circuit 24 by controlling the on / off of the two relays 22, 26. For example, when the vehicle 100 is running, the processing circuit 18 is configured to turn on the main relay 22 and turn off the sub-relay 26. As a result, when the vehicle 100 is running, the battery 12 and the auxiliary device 102 are connected via the main circuit 20.

[0016] Some of the auxiliary devices 102 mounted on the vehicle 100 are supplied with power from the battery 12 even while the vehicle 100 is parked. Therefore, if the vehicle 100 is left unused for a long period of time, the voltage of the battery 12 may drop, causing the battery to run out. In order to avoid such a situation, it is possible to detach the terminal 14 of the power supply device 10 from the auxiliary device 102 before the vehicle 100 is left unused for a long period of time. On the other hand, in recent years, as in this embodiment, a lithium ion battery is sometimes adopted as the battery 12 instead of a lead storage battery. The internal resistance of a lithium ion battery is significantly smaller than the internal resistance of a lead storage battery. Therefore, in the case where a lithium ion battery is adopted as the battery 12 instead of a lead storage battery, if the terminal 14 of the power supply device 10 is detached from the auxiliary device 102 and then reattached to the auxiliary device 102, a sudden large current (so-called inrush current) may be generated, which may affect the auxiliary device 102. This problem is not limited to the case where a lithium ion battery is used as battery 12, but can similarly occur even when a battery with a relatively low internal resistance is used.

[0017] In consideration of the above circumstances, the power supply device 10 of this embodiment is provided with a bypass circuit 24 having a sub-relay 26 that bypasses the main relay 22, in addition to the main circuit 20 that connects the battery 12 and the auxiliary equipment 102 via the main relay 22. The processing circuit 18 is configured to be able to identify appropriate timings for switching on and off each of the two relays 22, 26 when the vehicle 100 is parked, based on the current value detected by the current sensor 16. In this regard, a series of processes executed by the processing circuit 18 will be described together with changes in the current value detected by the current sensor 16 with reference to Figures 2 and 3.

[0018] As shown in FIG. 2, first, the processing circuit 18 judges whether the vehicle 100 is parked or not in response to, for example, an operation on a main switch (step S10). In this case, the processing circuit 18 of the power supply device 10 may receive, for example, a predetermined signal indicating that the vehicle 100 is parked from a higher-level control unit provided in the vehicle 100. Alternatively, the processing circuit 18 may judge whether the vehicle 100 is parked or not based on a current value detected by the current sensor 16. As shown in period A in FIG. 3, while the vehicle 100 is running, the battery 12 is repeatedly charged and discharged, so that the current value detected by the current sensor 16 fluctuates greatly. In contrast, as shown in period B in FIG. 3, while the vehicle 100 is parked, the battery 12 is not charged and supplies power only to the processing circuit 18 and (some) of the auxiliary equipment 102, so that the current value detected by the current sensor 16 is relatively stable. For this reason, the processing circuit 18 may judge that the vehicle 100 is parked when the fluctuation of the current value detected by the current sensor 16 is within a predetermined range.

[0019] Next, the processing circuit 18 judges whether the current value detected by the current sensor 16 is equal to or less than the first predetermined value P1 (step S12). When the battery 12 supplies power to both the processing circuit 18 and the auxiliary device 102, the current value detected by the current sensor 16 is stable at the first value A1, as shown in period B in FIG. 3. In contrast, when the terminal 14 of the power supply device 10 is electrically disconnected from the auxiliary device 102, the power supply from the battery 12 to the auxiliary device 102 is stopped, but the power supply from the battery 12 to the processing circuit 18 is continued. As a result, the current value detected by the current sensor 16 drops to or less than the first predetermined value P1, as shown in period C in FIG. 3. That is, the first predetermined value P1 indicates the maximum current value supplied from the battery 12 to the processing circuit 18 while the vehicle 100 is parked. Therefore, when the current detected by the current sensor 16 becomes equal to or less than the first predetermined value P1, the processing circuit 18 can determine that the terminal 14 of the power supply device 10 has been electrically disconnected from the auxiliary device 102. Note that the first predetermined value P1 does not necessarily have to coincide with the maximum current value supplied from the battery 12 to the processing circuit 18 while the vehicle 100 is parked, and may be set to a value larger than the maximum current value, for example.

[0020] If the answer is NO in step S12, the processing circuit 18 waits for a certain period of time (step S16) and then returns to the processing of step S12. As a result, while the terminal 14 of the power supply device 10 is connected to the auxiliary device 102, the processing of steps S12 and S16 is repeated at regular intervals. Although not particularly limited, the certain period of time is, for example, 1 hour, 12 hours, or 24 hours.

[0021] On the other hand, if the answer is YES in step S12, the processing circuit 18 turns on the sub-relay 26 (step S14). As a result, the battery 12 and the auxiliary device 102 are connected via both the main circuit 20 and the bypass circuit 24. At this time, the power supply from the battery 12 to the processing circuit 18 continues. After that, the processing circuit 18 turns off the main relay 22 (step S18). As a result, the battery 12 and the auxiliary device 102 are connected via the bypass circuit 24 instead of the main circuit 20. Note that the power supply from the battery 12 to the processing circuit 18 continues in the same manner as before the main relay 22 was turned off. Therefore, as shown in the period D in FIG. 3, the current detection value by the current sensor 16 continues to indicate a value equal to or less than the first predetermined value P1.

[0022] The order of the process of step S14 and the process of step S18 is not particularly limited. For example, the processing circuit 18 may simultaneously execute the process of step S14 and the process of step S18. That is, the processing circuit 18 may turn on the sub-relay 26 and turn off the main relay 22. Alternatively, the processing circuit 18 may execute the process of step S18 and then execute the process of step S14.

[0023] In this state, when the terminal 14 of the power supply device 10 is electrically reattached to the auxiliary device 102, the battery 12 and the auxiliary device 102 are electrically reconnected via the bypass circuit 24. At this time, a sudden large current (so-called inrush current) may occur, but the bypass circuit 24 has a higher resistance than the main circuit 20. Therefore, the occurrence of inrush current can be suppressed compared to when the battery 12 and the auxiliary device 102 are electrically connected via the main circuit 20 (period E1 in FIG. 3).

[0024] After the inrush current is alleviated, the processing circuit 18 judges whether the current value detected by the current sensor 16 is equal to or greater than the second predetermined value P2 (step S20). When the battery 12 and the auxiliary device 102 are electrically reconnected, the power supply from the battery 12 to the auxiliary device 102 is resumed. At this time, the power supply from the battery 12 to the processing circuit 18 is also continued. As a result, in a period E shown in FIG. 3, the current value detected by the current sensor 16 indicates the sum of the current value supplied from the battery 12 to the processing circuit 18 and the current value supplied from the battery 12 to the auxiliary device 102 while the vehicle 100 is parked. Therefore, the current value detected in the period E is significantly larger than the current values ​​detected in the periods C and D. Therefore, the second predetermined value P2 is set to a value larger than the first predetermined value P1.

[0025] When the battery 12 and the auxiliary device 102 are reconnected, the battery 12 and the auxiliary device 102 are connected via the bypass circuit 24 having a high resistance instead of the main circuit 20. Therefore, as shown in the period F in FIG. 3, the current value detected by the current sensor 16 is significantly smaller than the value when the battery 12 and the auxiliary device 102 are connected via the main circuit 20, that is, the current value detected in the period B. In detail, the current value detected in the period F is smaller than the current value detected in the period B according to the difference in resistance between the main circuit 20 and the bypass circuit 24. Therefore, it is preferable that the second predetermined value P2 is larger than the first predetermined value P1 and smaller than the first value A1. By setting the second predetermined value P2 in this manner, the processing circuit 18 can determine that the terminal 14 of the power supply device 10 has been electrically reattached to the auxiliary device 102 when the current detection value by the current sensor 16 becomes equal to or larger than the second predetermined value P2 (i.e., YES in step S20).

[0026] If the answer is YES in step S20, the processing circuit 18 turns on the main relay 22 (step S22). As a result, the battery 12 and the auxiliary device 102 are connected via both the main circuit 20 and the bypass circuit 24. At this time, power is supplied from the battery 12 to the auxiliary device 102 via both the main circuit 20 and the bypass circuit 24. Thereafter, the processing circuit 18 turns off the sub-relay 26 (step S26). As a result, the battery 12 and the auxiliary device 102 are connected via the main circuit 20 instead of the bypass circuit 24. At this time, power is supplied from the battery 12 to the auxiliary device 102 via the main circuit 20. As a result, as shown in a period F in FIG. 3, the current detection value by the current sensor 16 increases to a first value A1.

[0027] The order of the process of step S22 and the process of step S26 is not particularly limited. For example, the processing circuit 18 may execute the process of step S22 and the process of step S26 simultaneously. That is, the processing circuit 18 may turn on the main relay 22 and turn off the sub-relay 26.

[0028] If the result of step S20 is NO, the processing circuit 18 waits for a certain period of time (step S24) and then returns to the processing of step S20. As a result, the processing of steps S20 and S24 is repeated at regular intervals until the current value detected by the current sensor 16 stably indicates a value equal to or greater than the second predetermined value P2. Although not particularly limited, the certain period of time is, for example, 1 hour, 12 hours, or 24 hours.

[0029] As described above, the processing circuit 18 is configured to be able to identify appropriate timings for switching on and off each of the two relays 22, 26 based on the current value detected by the current sensor 16 while the vehicle 100 is parked. Specifically, when the current value detected by the current sensor 16 becomes equal to or less than the first predetermined value P1, the processing circuit 18 turns off the main relay 22 and turns on the sub-relay 26. With this configuration, when the terminal 14 of the power supply device 10 is subsequently reattached to the auxiliary device 102, the battery 12 and the auxiliary device 102 are connected via the bypass circuit 24 having a relatively high resistance. As a result, it is possible to suppress the generation of an inrush current when the terminal 14 of the power supply device 10 is attached to the auxiliary device 102 (see period E1 in FIG. 3).

[0030] In addition to the above, when the detected current value becomes equal to or greater than the second predetermined value after the main relay 22 is turned off and the sub-relay 26 is turned on, the processing circuit 18 turns on the main relay 22 and turns off the sub-relay 26. With this configuration, after the inrush current is suppressed by the bypass circuit 24, power can be supplied from the battery 12 to the auxiliary device 102 via the main circuit 20, which has a relatively low resistance. This makes it possible to prevent a portion of the power supplied from the battery 12 to the auxiliary device 102 from being consumed by the high resistance of the bypass circuit 24.

[0031] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical usefulness alone or in combination. [Explanation of symbols]

[0032] 10:Power supply 12:Battery 14: Terminal 16: Current sensor 18: Processing circuit 20: Main circuit 22: Main relay 24: Bypass circuit 26: Sub-relay 28:Resistor 100: Vehicle 102: Auxiliary equipment A1: First value P1: 1st predetermined value P2: Second predetermined value

Claims

1. A power supply device that supplies power to an auxiliary device mounted on a vehicle, Batteries and A terminal connected to the auxiliary equipment; a current sensor for detecting a discharge current of the battery; a main circuit having a main relay and connecting the battery and the terminal via the main relay; a bypass circuit having a sub-relay, bypassing the main relay via the sub-relay and having a resistance higher than that of the main circuit; a processing circuit for controlling the main relay and the sub-relay based on a current value detected by the current sensor; Equipped with the processing circuit is configured to turn off the main relay and turn on the sub-relay when the detected current value becomes equal to or less than a first predetermined value while the vehicle is parked. power supply.

2. 2. The power supply device according to claim 1, wherein the processing circuit is configured to turn on the main relay and turn off the sub-relay when the detected current value becomes equal to or greater than a second predetermined value after the processing circuit turns off the main relay and turns on the sub-relay.

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