Power supply system

Abstract

To identify a battery unit whose insulation resistance has lowered, without installing an insulation resistance detector for each battery unit.SOLUTION: A plurality of battery units Bu is connected in parallel to the cathode power line PL and anode power line PN of a power supply system 1 via a first relay 3. Each battery unit Bu is connected via a second relay 4 to a ground line SL that determines the potential that constitutes the basis of circuit operation of the battery units Bu. An insulation resistance detector 5 detects a decline in insulation resistance of the power supply system 1 (a circuit including the cathode power line PL and anode power line PN). When a decline in insulation resistance is detected, a control device 6 sequentially turns off the first relay 3 and second relay 4 of the battery units Bu, thereby identifying a battery unit Bu whose insulation resistance has lowered.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power supply system.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2016-219229 (Patent Document 1) discloses a power supply device including a battery group in which a plurality of battery bodies each having a positive electrode switch connected to the positive electrode side of a secondary battery and a negative electrode switch connected to the negative electrode side are connected in parallel. The power supply device of this Patent Document 1 includes insulation resistance detection means for detecting the insulation resistance of each battery body. Then, by comparing the switching commands of the positive electrode switch and the negative electrode switch with the insulation resistance of each battery body, abnormalities of the positive electrode side switch and the negative electrode side switch are diagnosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a power supply device, it is desirable to detect a decrease in insulation resistance (leakage). Further, in a power supply device in which a plurality of battery bodies (battery units) are connected in parallel, when a decrease in insulation resistance is detected, it is desirable to identify the battery unit in which the insulation resistance has decreased (the battery unit in which leakage has occurred). In the power supply device of Patent Document 1, since insulation resistance detection means (insulation resistance detectors) are provided for each battery unit, it is easy to identify the battery unit in which the insulation resistance has decreased. However, as many insulation resistance detectors as the number of battery units are required.

[0005] An object of the present disclosure is to make it possible to identify a battery unit in which the insulation resistance has decreased without providing an insulation resistance detector for each battery unit.

Means for Solving the Problems

[0006] The power supply system of the present disclosure is a power supply system having a positive power line and a negative power line, in which a plurality of battery units are connected in parallel. The power supply system includes a first relay disposed between the positive terminal of the battery unit and the positive power line and between the negative terminal of the battery unit and the negative power line, a second relay disposed between the ground line that determines the reference potential of the circuit operation of the battery unit and the battery unit, an insulation resistance detector connected to the positive power line and the negative power line to detect the insulation resistance of the power supply system, and a control device that controls the opening and closing of the first relay and the second relay. The first relay and the second relay are provided for each of the battery units. When a decrease in the insulation resistance of the power supply system is detected, the control device sequentially opens the first relay and the second relay of the battery unit to identify the battery unit with the decreased insulation resistance.

[0007] According to this configuration, the power supply system is composed of a plurality of battery units connected in parallel. Each battery unit includes a first relay disposed between the positive terminal and the positive power line of the power supply system and between the negative terminal and the negative power line of the power supply system. Each battery unit includes a second relay disposed between the ground line that determines the reference potential of the circuit operation of the battery unit and the battery unit. An insulation resistance detector connected to the positive power line and the negative power line detects the insulation resistance of the power supply system. The control device controls the opening and closing of the first relay and the second relay.

[0008] When a decrease in the insulation resistance of the power supply system is detected by the insulation resistance detector, the control device sequentially opens the first relay and the second relay of the battery unit to identify the battery unit with the decreased insulation resistance. Therefore, it is possible to identify the battery unit with the decreased insulation resistance without providing an insulation resistance detector for each battery unit.

[0009] When the control device opens the first relay and the second relay of the battery unit, if the insulation resistance detected by the insulation resistance detector becomes normal, the control device may specify that the insulation resistance of the battery unit is decreased.

[0010] Preferably, the battery unit includes a battery pack and a booster for boosting the voltage of the battery pack, and a first relay may be disposed between the positive power line and the negative power line and the booster.

[0011] According to this configuration, the voltage boosted by the booster can be output from the power supply system.

[0012] Preferably, the first relay and the second relay of the battery unit identified as having a reduced insulation resistance may be opened to electrically disconnect the battery unit from the power supply system and operate the power supply system.

[0013] According to this configuration, it is possible to electrically disconnect a battery unit with an abnormal insulation resistance and continue the operation of the power supply system.

Advantages of the Invention

[0014] According to the present disclosure, it is possible to identify a battery unit with a reduced insulation resistance without providing an insulation resistance detector for each battery unit.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0016] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the figures, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0017] FIG. 1 is a diagram showing a schematic configuration of a power supply system 1 according to an embodiment of the present disclosure. Referring to FIG. 1, the power supply system 1 includes a plurality of battery units Bu (Bu1 to Bun: n is a positive integer), a positive power line PL, a negative power line PN, an insulation resistance detector 5, and a control device 6. The number (n) of battery units Bu constituting the power supply system 1 is arbitrary, and may be 10, or may be 100.

[0018] The battery unit Bu includes a battery pack 10 and a PCU (Power Control Unit) 20. The battery pack 10 includes a battery module in which a plurality of single batteries (battery cells) are electrically connected in series, a BMS (Battery Management System), and a main relay. The single battery may be, for example, a lithium-ion secondary battery. The BMS performs charge and discharge control of the battery module, equalization of the voltages of the battery cells, etc., and may be composed of, for example, a monitoring unit (voltage sensor, current sensor, temperature sensor, etc.) and a battery ECU (Electronic Control Unit). The main relay connects / disconnects the battery module and an external circuit (in this embodiment, the PCU 20). The battery pack 10 may be a repurposed drive (high-voltage) battery pack (battery) mounted on an electric vehicle.

[0019] In the present embodiment, the PCU 20 is composed of a DC / DC converter and an ECU that controls the DC / DC converter, and is a booster that boosts the voltage of the battery pack 10 (battery module).

[0020] The positive electrode terminal of the battery unit Bu (the positive electrode terminal of the PCU 20) is connected to the positive power line PL, and the negative electrode terminal of the battery unit Bu (the negative electrode terminal of the PCU 20) is connected to the negative power line PN. A first relay 3 (3-1 to 3-n) is arranged between the positive electrode terminal and the positive power line PL, and between the negative electrode terminal and the negative power line PN. When the first relay 3 is closed (ON), the battery unit Bu, the positive power line PL, and the negative power line PN are electrically connected. When the first relay 3 is opened (OFF), the battery unit Bu, the positive power line PL, and the negative power line PM are electrically disconnected.

[0021] A plurality of battery units Bu1 to Bun are electrically connected in parallel to the positive power line PL and the negative power line PN. Also, first relays 3-1 to 3-n are provided for each of the battery units Bu1 to Bun.

[0022] A plurality of battery units Bu1 to BUn are connected to the control ground line SL. The control ground line SL is a wiring that determines the potential serving as a reference for the operation of the circuit of the battery unit Bu (PCU 20, BMS of the battery pack 10, drive circuit of the main relay, etc.). Each of the battery units Bu1 to Bun is connected to the ground line SL via a second relay 4 (4-1 to 4-n9). When the second relay 4 is closed (ON), the battery unit Bu and the ground line SL are electrically connected. When the second relay 4 is opened (OFF), the battery unit Bu and the ground line SL are electrically disconnected. Note that the ground line SL may be connected to the housing (frame) of the power supply system 1.

[0023] The positive power line PL and the negative power line PN are connected to a load and also connected to an insulation resistance detector 5. The load may be, for example, an inverter that converts the DC power of the power supply system 1 into AC power. Thereby, the power supply system 1 can be used as an AC power supply. Also, the positive power line PL and the negative power line PN may be connected to an external power source (for example, a power grid), and the battery unit Bu (battery pack 10) may be configured to be chargeable.

[0024] The insulation resistance detector 5 detects a decrease in the insulation resistance (leakage) of the power supply system 1, and is, for example, an insulation resistance detector for a DC non-grounded circuit. In the present embodiment, the insulation resistance detector 5 connects the positive power line PL and the negative power line PN to the ground via a large resistor. When the insulation resistance of the power supply system 1 (the circuit including the positive power line PL and the negative power line PN) decreases, the current flowing through the insulation resistance detector 5 increases, so the value of the insulation resistance of the power supply system 1 can be detected based on the magnitude of the current. The insulation resistance detector 5 outputs the value of the insulation resistance of the power supply system 1 to the control device 6.

[0025] The control device 6 controls the opening and closing of the first relay 3 and the second relay 4. The control device 6 may be an ECU composed of a processor, a memory, etc. The control device 6 closes (turns ON) the first relay 3 and the second relay 4 of the battery unit Bu used for the power supply system 1, closes (turns ON) the main relay of the battery pack 10, and boosts the voltage of the battery pack 10 by the PCU 20 to output power. Also, when charging the battery unit Bu (battery pack 10), the first relay 3 and the second relay are closed (turned ON), the main relay of the battery pack 10 is closed (turned ON), and the PCU 20 controls the externally supplied power to the charging voltage of the battery pack 10 to perform charging.

[0026] In the power supply system 1, the insulation resistance of the battery unit Bu may decrease and leakage may occur. When leakage occurs, it is desirable to identify the leakage location (the location where the insulation resistance has decreased). A decrease in the insulation resistance of the battery unit Bu can be detected when the value of the insulation resistance detected by the insulation resistance detector 5 becomes equal to or less than a predetermined value.

[0027] FIG. 2 is a diagram showing a schematic configuration of the power supply system 1A in the comparative example. In the power supply system 1A of the comparative example, each of the battery units Bu1 to Bun is directly connected to the ground line SL without passing through a relay. The other configurations are the same as those of the power supply system 1.

[0028] In the power supply system 1A of the comparative example, for example, assume that during the use of all battery units Bu, leakage occurs in the battery unit Bu2, and the insulation resistance detected by the insulation resistance detector 5 becomes equal to or lower than a predetermined value. In order to attempt to identify the location of the leakage, the first relays 3-1 to 3-n of each battery unit Bu1 to Bun are sequentially opened (turned OFF) to disconnect each battery unit Bu to Bun from the power supply system 1 (the positive power line PL and the negative power line PN). For example, as shown in FIG. 2, the first relay 3-2 of the battery unit Bu2 in which leakage has occurred (the insulation resistance has decreased) is opened (turned OFF), and the other first relays 3 are closed (turned ON) to disconnect the battery unit Bu2 from the power supply system 1A. In this case, as indicated by the dashed-dotted line, current flows from the ground line SL into the battery unit Bu2, and the leakage current ID of the battery unit Bu2 does not decrease enough to detect the leakage. Therefore, the value of the insulation resistance detected by the insulation resistance detector 5 does not change, and even if the battery unit Bu2 is disconnected from the power supply system 1, the location of the decrease in the insulation resistance cannot be identified.

[0029] In the present embodiment, by providing the second relay 4 that cuts off the electrical connection between the battery unit Bu and the ground line SL, it becomes possible to identify the location where the insulation resistance has decreased (the location of the leakage).

[0030] FIG. 3 is a diagram for explaining a state in which a leakage current has occurred in the power supply system 1 according to the present embodiment. In FIG. 3, during the use of all the battery units Bu, the insulation resistance of the battery unit Bu has decreased and a leakage current has occurred, and the insulation resistance detected by the insulation resistance detector 5 has become equal to or less than a predetermined value. When the insulation resistance detected by the insulation resistance detector 5 becomes equal to or less than the predetermined value, the first relays 3-1 to 3-n and the second relays 4-1 to 4-n of the respective battery units Bu1 to Bun are sequentially opened (turned OFF), and the respective battery units Bu to Bun are disconnected from the positive power line PL, the negative power line PN, and the ground line SL. The first relay 3-2 and the second relay 4-2 of the battery unit Bu2 are opened (turned OFF), and the battery unit Bu2 is disconnected from the power supply system 1. By opening (turning OFF) the second relay 4-2, the battery unit Bu and the ground line SL are electrically disconnected, so that the flow of current from the ground line SL into the battery unit Bu2 can be suppressed. For this reason, the leakage current ID from the battery unit Bu2 does not occur, the value of the insulation resistance detected by the insulation resistance detector 5 becomes larger than the predetermined value, and the insulation resistance returns to a normal value. Therefore, it is possible to specify that leakage (decrease in insulation resistance) has occurred in the battery unit Bu2.

[0031] FIG. 4 is a flowchart showing an example of insulation abnormality location identification processing executed by the control device 6. This flowchart shows an example of insulation abnormality identification processing when all the battery units Bu are in use. This flowchart is executed when the value of the insulation resistance detected by the insulation resistance detector 5 becomes equal to or less than a predetermined value, a leakage current occurs in any of the battery units Bu, and a decrease in the insulation resistance (abnormality of the insulation resistance) of the power supply system 1 occurs.

[0032] First, in step (hereinafter, steps are abbreviated as "S") 10, after setting k to 0, proceed to S11. In S11, a new k is obtained by adding 1 to k (k←k + 1). When S11 is processed for the first time, k = 1. In the subsequent S12, the first relay 3 - k and the second relay 4 - k are turned off, and the other first relay 3 and second relay 4 are turned on. When S12 is processed for the first time, the first relay 3 - 1 and the second relay 4 - are turned off, and the other first relay 3 and second relay 4 are turned on.

[0033] In the subsequent S13, it is determined whether the insulation resistance detected by the insulation resistance detector 5 has returned to normal. If the value of the insulation resistance detected by the insulation resistance detector 5 is less than or equal to a predetermined value, the insulation resistance has not returned to normal, so a negative determination is made and the process proceeds to S14. If the value of the insulation resistance detected by the insulation resistance detector 5 is greater than the predetermined value, it is determined that the insulation resistance has returned to normal, so a positive determination is made and the process proceeds to S15.

[0034] In S14, it is determined whether k is greater than or equal to n. If k is less than n, a negative determination is made and the process returns to S11. In the subsequent S11, 1 is added to k, and the processing after S12 is repeated. As a result, the first relay 3 and the second relay of the battery unit Bu are sequentially turned off, and it is determined whether the insulation resistance is normal. If k is greater than or equal to n, a positive determination is made and the process proceeds to S16. In S16, it is determined that the abnormal location of the insulation resistance (the location where the insulation resistance has decreased: the leakage location) cannot be identified, and this routine is terminated.

[0035] In S15, in S12, it is identified that an abnormality (for example, leakage) of the insulation resistance has occurred in the battery unit Buk in which the first relay 3 - k and the second relay 4 - k are turned off, and this routine is terminated.

[0036] When the battery unit Bu with insulation abnormality can be identified, the power supply system 1 may disconnect the battery unit Bu in which the abnormality of the insulation resistance is identified from the power supply system 1 (while maintaining the opening (OFF) of the first relay 3 and the second relay 4 of the battery unit Bu) and continue the operation of the power supply system 1. When the location of the insulation resistance abnormality cannot be identified (when S16 is processed), it is preferable to stop the operation of the power supply system 1.

[0037] According to the present embodiment, each of the battery units Bu1 to Bun includes first relays 3-1 to 3-n arranged between the positive electrode terminal and the positive power line PL of the power supply system 1 and between the negative electrode terminal and the negative power line PN of the power supply system 1. Each of the battery units Bu1 to Bun includes second relays 4-1 to 4-n arranged between the ground line SL that determines the reference potential of the circuit operation of the battery unit Bu and the battery unit Bu. An insulation resistance detector 5 connected to the positive power line PL and the negative power line PN detects the insulation resistance of the power supply system 1. When the control device 6 detects a decrease in the insulation resistance of the power supply system 1 by the insulation resistance detector 5, the control device 6 sequentially opens (turns OFF) the first relay 3 and the second relay 4 of the battery unit Bu to identify the battery unit Bu in which the insulation resistance has decreased. Therefore, it is possible to identify the battery unit Bu in which the insulation resistance has decreased without providing an insulation resistance detector 5 for each battery unit Bu.

[0038] When the control device opens (turns OFF) the first relay 3 and the second relay 4 of the battery unit Bu, if the insulation resistance detected by the insulation resistance detector 5 returns to normal, it can be determined that the insulation resistance of the battery unit Bu has decreased.

[0039] In the above embodiment, the battery unit Bu includes the PCU 20 that boosts the voltage of the battery pack 10. However, the configuration may be such that the PCU 20 is not provided and the positive electrode terminal and the negative electrode terminal of the battery pack 10 are connected to the positive power line PL and the negative power line PN.

[0040] In the flowchart of FIG. 4, an example in which the power supply system 1 is operated using all the battery units Bu has been described. However, when the power supply system 1 is operated using some of the battery units Bu, when a decrease in the insulation resistance of the power supply system 1 occurs, it is also possible to identify the abnormal location (the location where leakage occurs) of the insulation resistance. In this case, with the first relays 3 and the second relays of the unused battery units Bu maintained in the open (OFF) state, the first relays 3 and the second relays 4 of the used battery units Bu (the battery units Bu connected to the positive power line PL and the negative power line PN) are sequentially opened (turned OFF), and the battery unit Bu with the decreased insulation resistance may be identified. Note that the order in which the first relays 3 and the second relays 4 are opened (turned OFF) may be arbitrary.

[0041] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above-described embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0042] 1, 1A Power supply system, 3 First relay, 4 Second relay, 5 Insulation resistance detector, 6 Control device, 10 Battery pack, 20 PCU, PL Positive power line, PN Negative power line, SL Ground line.

Claims

1. A power supply system having a positive power line and a negative power line, in which a plurality of battery units are connected in parallel, a first relay disposed between the positive electrode terminal of the battery unit and the positive power line, and between the negative electrode terminal of the battery unit and the negative power line; a second relay disposed between the ground line that determines the potential serving as the reference for the circuit operation of the battery unit and the battery unit; an insulation resistance detector connected to the positive power line and the negative power line to detect the insulation resistance of the power supply system; a control device that controls the opening and closing of the first relay and the second relay, and the first relay and the second relay are provided for each of the battery units, wherein the control device when a decrease in the insulation resistance of the power supply system is detected, sequentially opens the first relay and the second relay of the battery unit to identify the battery unit in which the insulation resistance has decreased. A power supply system.

2. The control device when the first relay and the second relay of the battery unit are opened and the insulation resistance returns to normal, identifies that the insulation resistance of the battery unit has decreased. The power supply system according to claim 1.

3. The battery unit includes a battery pack and a booster that boosts the voltage of the battery pack, wherein the first relay is disposed between the positive power line and the negative power line and the booster. The power supply system according to claim 1 or claim 2.

4. Open the first relay and the second relay of the battery unit in which the insulation resistance has been identified as decreased to electrically disconnect the battery unit from the power supply system and operate the power supply system. The power supply system according to claim 2.

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