JP2012083175A - Grounding detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grounding detecting device which detects grounding of a positive electrode bus bar or a negative electrode bus bar.SOLUTION: A grounding detecting device 100 includes: a first switch circuit 82 for performing connection/disconnection of a first path between a positive electrode bus bar 1 connected to a positive electrode side of secondary battery sections 30a, 30b and 30c and a ground potential position; a second switch circuit 84 for performing connection/disconnection of a second path between a negative electrode bus bar 2 connected to a negative electrode side of the secondary battery sections 30a, 30b and 30c and the ground potential position; and a grounding detecting section 90 for detecting grounding of the positive electrode bus bar 1 or the negative electrode bus bar 2 based on the current of the first path or the second path.

Description

  The present invention relates to a ground fault detection apparatus, and more particularly, to a ground fault detection apparatus that detects that a positive or negative bus is grounded.

  Energy is effectively used by using a power storage device such as a secondary battery. For example, in recent years, a photovoltaic power generation system has been actively developed as environmentally friendly clean energy, but since a photoelectric conversion module that converts sunlight into electric power does not have a storage function, it is combined with a secondary battery. Sometimes used. For example, energy is effectively used by charge / discharge control in which electric power generated by a photoelectric conversion module is once charged in a secondary battery and discharged from the secondary battery in response to a request from an external load or the like.

  As a technique related to the present invention, for example, Patent Document 1 discloses a solar battery, a plurality of secondary batteries charged with the solar battery, and a secondary battery connected between each secondary battery and the solar battery. A solar battery power supply device comprising: a charge switch for controlling charging of a secondary battery; a discharge switch connected between each secondary battery and a load; and a control circuit for controlling the charge switch and the discharge switch. It is disclosed. Here, the control circuit specifies the priority order of the secondary batteries to be charged by controlling a plurality of charge switches, charges the secondary battery with a higher priority before the secondary battery with a lower priority, It is disclosed that when a secondary battery having a higher rank is charged with a predetermined capacity, a secondary battery having a lower priority is charged.

JP 2003-111301 A

  By the way, there is a power supply system in which the positive bus connected to the positive terminal of the secondary battery and the negative bus connected to the negative terminal of the secondary battery are not grounded. In this case, when the positive bus or the negative bus has a ground fault, it may be impossible to supply a suitable power because the potential fluctuates. Therefore, it is desirable to detect the occurrence of a ground fault.

  The objective of this invention is providing the ground fault detection apparatus which detects generation | occurrence | production of a ground fault.

  A ground fault detection device according to the present invention includes a first switch circuit that connects / cuts off a first path between a positive electrode bus connected to a positive electrode side of a secondary battery unit and a ground potential location, and a negative electrode side of the secondary battery unit The second switch circuit for connecting / cutting off the second path between the negative electrode bus connected to the ground and the ground potential location, and the positive or negative bus is grounded based on the current in the first path or the second path And a ground fault detection unit for detecting.

  According to the ground fault detection device having the above configuration, it is possible to detect that the positive bus or the negative bus is grounded based on the current of the first path or the second path.

In embodiment which concerns on this invention, it is a figure which shows a ground fault detection apparatus, a control part, and the electric power supply system by which a ground fault is detected by a ground fault detection apparatus. In embodiment concerning this invention, it is a flowchart which shows the procedure in which a ground fault is detected by the ground fault detection apparatus. In embodiment which concerns on this invention, when a positive electrode bus line has a ground fault, it is a timing chart at the time of detecting that the ground fault has generate | occur | produced.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In the following description, the secondary battery is described as being a lithium ion secondary battery, but other storage batteries that can be charged and discharged may be used. For example, a nickel hydride secondary battery, a nickel cadmium storage battery, a lead storage battery, a metal lithium ion secondary battery, or the like may be used.

  Also, in the following, in all the drawings, the same symbols are attached to the same elements, and the duplicate description is omitted. In the description in the text, the symbols described before are used as necessary.

  FIG. 1 is a diagram illustrating a ground fault detection device 100, a control unit 70, and a power supply system 10 in which a ground fault is detected by the ground fault detection device 100. First, the power supply system 10 will be described, and then the ground fault detection device 100 and the control unit 70 will be described.

  The power supply system 10 includes a solar cell module 20, breaker units 25 a, 25 b, 25 c, secondary battery units 30 a, 30 b, 30 c, a switching device 40, and a load 75.

  The solar cell module 20 is a photoelectric conversion device that converts sunlight into electric power. The positive electrode side terminal of the solar cell module 20 is connected to the one side terminal 402 a of the charging switch circuit 402 by the positive electrode bus 1. The negative electrode side terminal of the solar cell module 20 is connected to the negative electrode side terminals 252b, 254b, 256b of the negative electrode side breakers 252, 254, 256 of the breaker portions 25a, 25b, 25c and the negative electrode side terminal of the load 75 by the negative electrode bus 2. ing. Note that the generated power generated by the solar cell module 20 is DC power.

  Each of the secondary battery units 30a, 30b, and 30c is configured by connecting a plurality of secondary batteries in series. Each secondary battery includes a negative electrode made of a carbon material, an electrolytic solution for moving lithium ions, and a positive electrode active material capable of reversing lithium ions.

  The positive electrode side terminal of the secondary battery unit 30a is connected to the parallel processing circuit unit 404 via the positive electrode side breaker 251 of the breaker unit 25a, and the negative electrode side terminal is connected to the negative electrode bus 2 via the negative electrode side breaker 252 of the breaker unit 25a. It is connected to the. Moreover, as FIG. 1 shows, the secondary battery part 30b and the secondary battery 30c also have the structure similar to the secondary battery 30a.

  The breaker units 25a, 25b, and 25c are devices that are controlled to be cut off by the control unit 70 when it is necessary to protect the secondary battery units 30a, 30b, and 30c.

  The breaker unit 25 a includes a positive electrode side breaker 251 and a negative electrode side breaker 252. The positive electrode side breaker 251 is a cutoff circuit in which one side terminal 251a is connected to the parallel processing circuit unit 404 and the other side terminal 251b is connected to the positive electrode side terminal of the secondary battery unit 30a. The negative electrode side breaker 252 is a cutoff circuit in which one side terminal 252a is connected to the negative electrode side terminal of the secondary battery part 30a and the other side terminal 252b is connected to the negative electrode bus 2. Moreover, as FIG. 1 shows, the breaker part 25b and the breaker part 25c also have the structure similar to the breaker part 25a.

  The switching device 40 includes a charging switch circuit 402, a parallel processing circuit unit 404, and a discharging switch circuit 406.

  The parallel processing circuit unit 404 includes switch circuits 41a, 41b, 41c and resistance elements 42a, 42b, 42c.

  In the switch circuit 41a, one terminal 410a is connected to the other terminal 402b of the charging switch circuit 402 and one terminal 406a of the discharging switch circuit 406, and the other terminal 411a is one terminal 251a of the positive circuit breaker 251. It is a switch connected to. The switch circuit 41a can be configured by using, for example, a field effect transistor (FET). In this case, a parasitic diode in which a cathode terminal is connected to one side terminal 402a and an anode terminal is connected to the other side terminal 402b. It is formed. Further, as shown in FIG. 1, the switch circuit 41b and the switch circuit 41c have the same configuration as the switch circuit 41a.

  The resistance element 42 a has one terminal connected to the other terminal 402 b of the charging switch circuit 402 and one terminal 406 a of the discharging switch circuit 406, and the other terminal connected to the one terminal 251 a of the positive breaker 251. Is done. That is, the resistance element 42a is connected in parallel to the switch circuit 41a. Further, the resistance element 42b and the resistance element 42c have the same configuration as the resistance element 41a.

  Here, the operation of the parallel processing circuit unit 404 will be described. During normal operation, the switch circuits 41a, 41b, and 41c are on / off controlled by the control unit 70 in accordance with the potential difference of the voltage on the positive terminal side. Yes. The on-resistance values of the switch circuits 41a, 41b, and 41c are smaller than the resistance values of the resistance elements 42a, 42b, and 42c, respectively. Therefore, when the charging switch circuit 402 is also turned on by the control unit 70, the generated power generated by the solar cell module 20 is recharged via the switch circuits 41a, 41b, and 41c, respectively. 30b and 30c are charged.

  For example, when the secondary battery unit 30b is replaced, a voltage difference is generated between the one side terminal 253a of the positive electrode side breaker 253 and the one side terminals 251a and 255a of the positive electrode side breakers 251 and 255. At this time, the control unit 70 switches off the switch circuit 41b. Thereby, the generated power generated by the solar cell module 20 is charged in the secondary battery units 30a and 30c via the switch circuits 41a and 41c, but not in the secondary battery 30b. And when the voltage of the secondary battery part 30b is smaller than the voltage of the secondary battery parts 30a and 30b, between the one side terminals 251a and 255a of the positive electrode side breakers 251 and 255 and the one side terminal 253a of the positive electrode side breaker 253. Therefore, a current flows toward the positive side breaker 253 via the resistance element 42a and the resistance element 42b, or the resistance element 42c and the resistance element 42b, and the voltage difference is reduced.

  In the charging switch circuit 402, one terminal 402a is connected to the positive terminal of the solar cell module 20 by the positive electrode bus 1, and the other terminal 402b is connected to the one terminal 410a, 41a, 41b, 41c of the switch circuit 41a, 41b, 41c by the positive electrode bus 1. 410b and 410c and one side terminals of the resistance elements 42a, 42b, and 42c and one side terminal 406a of the discharge switch circuit 406. Switching control of the charging switch circuit 402 is performed under the control of the control unit 70. The charging switch circuit 402 can be configured using, for example, a field effect transistor (FET). In this case, the anode terminal is connected to the other side terminal 402b, and the cathode terminal is connected to the one side terminal 402a. A parasitic diode is formed.

  The discharge switch circuit 406 has one terminal 406a that is connected to the positive bus 1, and the other terminal 402b of the charge switch circuit 402, one terminal 410a, 410b, 410c of the switch circuit 41a, 41b, 41c, and the resistor elements 42a, 42b, It is a switch connected to one side terminal of 42c. The discharge switch circuit 406 is a switch in which the other-side terminal 406b is connected to the load 75 by the positive bus 1. Switching control of the discharge switch circuit 406 is performed under the control of the control unit 70. Note that the discharge switch circuit 406 can be configured using, for example, a field effect transistor (FET). In this case, the cathode terminal is connected to the one-side terminal 406a, and the anode terminal is connected to the other-side terminal 406b. A parasitic diode is formed.

  The load 75 is a load device in which one side terminal is connected to the other side terminal 406 b of the discharging switch circuit 406 by the positive electrode bus 1 and the other side terminal is connected to the positive electrode bus 2. Here, the load 75 is a load that operates with DC power, and for example, a personal computer or the like can be used.

  Next, the ground fault detection apparatus 100 will be described. The ground fault detection device 100 includes a first resistance element 80, a first switch circuit 82, a ground fault detection unit 90, a second switch circuit 84, and a second resistance element 86.

  The first resistance element 80 is a resistance element having one terminal connected to the positive electrode bus 1 and the other terminal connected to the one terminal 82 a of the first switch circuit 82. Note that the resistance value of the first resistance element 80 is a value determined in advance in order to suppress the current value that flows when the negative electrode bus 2 is grounded.

  The first switch circuit 82 has one terminal 82 a connected to the other terminal of the first resistance element 80, and the other terminal 82 b connected to the one terminal 84 a of the second switch circuit 84 and one terminal of the ground fault detector 90. 90a. The first switch circuit 82 can be configured using, for example, a field effect transistor (FET). In this case, the anode terminal is connected to the one-side terminal 82a, and the cathode terminal is connected to the other-side terminal 82b. A parasitic diode is formed. Note that the switching control of the first switch circuit 82 is performed by the control unit 70.

  The second switch circuit 84 has one terminal 84 a connected to the other terminal 82 b of the first switch circuit 82 and one terminal 90 a of the ground fault detector 90, and the other terminal 84 b being one of the second resistance elements 86. Connected to the side terminal. The second switch circuit 84 can be configured using, for example, a field effect transistor (FET). In this case, the cathode terminal is connected to the one side terminal 84a, and the anode terminal is connected to the other side terminal 84b. A parasitic diode is formed. The switching control of the second switch circuit 84 is performed by the control unit 70.

  The second resistance element 86 is a resistance element having one terminal connected to the other terminal of the second switch circuit 84 and the other terminal connected to the negative electrode bus 2. The resistance value of the second resistance element 86 is a value determined in advance in order to suppress the current value that flows when the positive electrode bus 1 is grounded.

  The ground fault detector 90 includes an I / V conversion resistance element 91, a high frequency filter 92, a full-wave rectifier circuit 93, a low frequency filter 94, a comparator 95, a reference voltage circuit 96, and a resistance element. 97, a capacitance element 98, and a determination circuit 99. In the ground fault detector 90, one terminal 90a is connected to a connection point between the first switch circuit 82 and the second switch circuit 84, and the other terminal 90b is grounded.

  The I / V conversion resistance element 91 has one terminal connected to a connection point between the first switch circuit 82 and the second switch circuit 84 through the one terminal 90a, and the other terminal connected through the other terminal 90b. It is a resistance element that is grounded. The current flowing through the I / V conversion resistance element 91 is converted into a voltage by the resistance component.

  The high frequency filter 92 is a filter circuit in which two input side terminals are connected to both side terminals of the I / V conversion resistance element 91 and an output side terminal is connected to the input side terminal of the full-wave rectifier circuit 93. The high frequency filter 92 receives the voltage signal output from the I / V conversion resistance element 91 as an input, and functions as a filter that cuts a high frequency (for example, 15 kHz to 20 kHz) component of the voltage signal. To do.

  The full-wave rectifier circuit 93 is a rectifier circuit whose input side terminal is connected to the output side terminal of the high frequency filter 92 and whose output side terminal is connected to the input side terminal of the low frequency filter 94. The full-wave rectifier circuit 93 functions as a rectifier circuit that full-wave rectifies the voltage signal filtered by the high-frequency filter 92.

  The low frequency filter 94 is a filter circuit whose input side terminal is connected to the output side terminal of the full-wave rectifier circuit 93 and whose output side terminal is connected to the first input side terminal of the comparator 95. The low frequency filter 94 is a filter circuit that cuts a low frequency (for example, 100 Hz to 120 Hz) component of the voltage signal rectified by the full wave rectifier circuit 93.

  The reference voltage circuit 96 is a circuit in which one terminal is connected to the second input terminal of the comparator 95 and the other terminal is grounded. The reference voltage circuit 96 has a function of outputting a predetermined reference voltage value (threshold value) in order to detect that the positive bus 1 or the negative bus 2 is grounded.

  The comparator 95 has a first input side terminal connected to the output side terminal of the low frequency filter 94, a second input side terminal connected to one side terminal of the reference voltage circuit 96, and an output side terminal connected to one side of the resistance element 97. It is a comparison circuit connected with a side terminal. The comparator 95 has a function of comparing the voltage signal filtered by the low frequency filter 94 with the voltage value output by the reference voltage circuit 96. The comparator 95 outputs Low when the value of the voltage signal is larger than the reference voltage value, and outputs High when the value of the voltage signal is smaller than the reference voltage value.

  The resistance element 97 is a resistance element having one terminal connected to the output terminal of the comparator 95 and the other terminal connected to the one terminal of the capacitor 98 and the input terminal of the determination circuit 99.

  The capacitive element 98 is a capacitive element in which one terminal is connected to the other terminal of the resistance element 97 and the input terminal of the determination circuit 99, and the other terminal is grounded. Here, the resistor element 97 and the capacitor element 98 function together as a time constant circuit, and specifically, based on the change in the output value of the comparator 95, the resistance value of the resistor element 97 and the capacitance value of the capacitor element 98. It functions as a time constant circuit that changes the value with a time constant determined by.

  The determination circuit 99 is a circuit in which the input side terminal is connected to the other side terminal of the resistance element 97 and the one side terminal of the capacitive element 98, and the output side terminal is connected to the control unit 70. In the determination circuit 99, the output value of the time constant circuit formed by the resistance element 97 and the capacitance element 98 (the potential of the other side terminal of the resistance element 97 and the one side terminal of the capacitance element 98) is changed from Low to High. It is determined whether or not the changing time exceeds a predetermined determination time (for example, 2 seconds). When the change signal of the output value of the time constant circuit described above does not exceed the determination time, the determination circuit 99 determines that a ground fault has not occurred and outputs Low, and the change signal is the determination signal. It has a function of determining that a ground fault has occurred when the time is exceeded and outputting High.

  Next, the control unit 70 will be described. The control unit 70 includes a charge / discharge processing unit 702 and a ground fault handling unit 704. In addition, each structure of the control part 70 may be comprised with a hardware, and can also be comprised with software.

  The charge / discharge processing unit 702 has a function of performing on / off control of the charging switch circuit 402 and the discharging switch circuit 406. In addition, the charge / discharge processing unit 702 temporarily charges the secondary battery units 30a, 30b, and 30c with the generated power generated by the solar cell module 20, and uses the discharged power discharged from the secondary battery units 30a, 30b, and 30c. In order to supply the load 75, the charging switch circuit 402 and the discharging switch circuit 406 are turned on.

  Further, the charge / discharge processing unit 702 acquires the SOC of the secondary battery units 30a, 30b, and 30c, and at least one of the SOCs of the secondary battery units 30a, 30b, and 30c is greater than a predetermined overcharge reference value. The secondary battery units 30a, 30b, 30c have a function of turning off the charging switch circuit 402 in order to prevent the secondary battery units 30a, 30b, 30c from being overcharged.

  Further, the charge / discharge processing unit 702 acquires the SOC of the secondary battery units 30a, 30b, and 30c, and at least one of the SOCs of the secondary battery units 30a, 30b, and 30c becomes smaller than a predetermined overdischarge reference value. The secondary battery units 30a, 30b, 30c have a function of turning off the discharge switch circuit 406 in order to prevent the secondary battery units 30a, 30b, 30c from being overdischarged.

  The ground fault handling processing unit 704 has a function of controlling the first switch circuit 82, the second switch circuit 84, and the breaker units 25a, 25b, and 25c.

  The ground fault response processing unit 704 has a function of turning off the first switch circuit 82 and turning on the second switch circuit 84 in order to detect whether or not the positive bus 1 is grounded. Here, when the positive bus 1 is grounded, current flows from the ground side to the negative bus 2 via the I / V conversion resistance element 91, the second switch circuit 84, and the second resistance element 86. A current path is formed. When the positive bus 1 has a ground fault, the ground fault detection unit 90 detects that a ground fault has occurred, and the output signal of the determination circuit 99 becomes High. At this time, the ground fault handling unit 704 determines that the positive electrode bus 1 is grounded, and shuts off the breaker units 25a, 25b, and 25c.

  Further, the ground fault handling processing unit 704 turns on the first switch circuit 82 and turns off the second switch circuit 84 in order to detect whether or not the negative electrode bus 2 is grounded. Here, when the negative electrode bus 2 is grounded, a current flows from the positive electrode bus 1 side to the ground side via the first resistance element 80, the first switch circuit 82, and the I / V conversion resistance element 91. A current path is formed. When the negative electrode bus 2 is grounded, it is detected by the ground fault detection unit 90 that the ground fault is detected, and the output signal of the determination circuit 99 becomes High. At this time, the ground fault handling unit 704 determines that the negative electrode bus 2 is grounded, and shuts off the breaker units 25a, 25b, and 25c.

  Next, the operation of the above configuration will be described with reference to FIG. FIG. 2 is a flowchart showing a procedure for detecting a ground fault by the ground fault detection apparatus 100. First, the first switch circuit 82 and the second switch circuit 84 are turned off, and it is confirmed that no current flows through the I / V conversion resistance element 91 (S2). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. Thereby, an initial check is performed to confirm whether or not the ground fault detection device 100 is in a normal state.

  Next, the first switch circuit 82 is turned on (S4). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. Thereby, the detection of whether or not the negative electrode bus 2 is grounded is started. Next, it is determined whether or not 5 seconds have elapsed since the detection of the ground fault of the negative electrode bus 2 is started (S6). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. When it is determined that 5 seconds have elapsed since the detection of the ground fault of the negative electrode bus 2 is started, the process proceeds to S12.

  When it is determined that 5 seconds have not elapsed since the detection of the ground fault of the negative electrode bus 2 is started, it is determined whether or not the output signal of the determination circuit 99 is High (S8). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. When the output signal of the determination circuit 99 is Low, the process returns to S6 again.

  When the output signal of the determination circuit 99 is High, it is determined that the negative electrode bus 2 is grounded, and the breakers 25a, 25b, and 25c are shut off (S10). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70.

  In step S12, after 3 seconds have elapsed since the first switch circuit 82 was turned off (S12), the second switch circuit 84 is turned on (S14). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. Thereby, the ground fault detection regarding the negative electrode bus line 2 is finished, and detection of whether or not the positive electrode bus line 1 is grounded is started. The reason why the first switch circuit 82 is turned off and the second switch circuit 84 is turned on after 3 seconds have elapsed is immediately before the first switch circuit 82 is turned off. This is because it is necessary to determine whether or not the High signal has passed for 2 seconds or more when the output of the comparator 95 is switched from High to Low.

  Next, it is determined whether or not 5 seconds have elapsed since the detection of the ground fault of the positive bus 1 was started (S16). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. When it is determined that 5 seconds have elapsed since the detection of the ground fault of the positive bus 1 is started, the process proceeds to the END process.

  When it is determined that 5 seconds have not elapsed since the detection of the ground fault of the positive bus 1 is started, it is determined whether or not the output signal of the determination circuit 99 is High (S18). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70. When the output signal of the determination circuit 99 is Low, the process returns to S16 again.

  When the output signal of the determination circuit 99 is High, it is determined that the positive bus 1 is grounded, and the breakers 25a, 25b, and 25c are shut off (S18). This process is executed by the function of the ground fault handling processing unit 704 of the control unit 70.

  According to the above configuration, when the ground fault is generated based on the result of the ground fault detection performed by the ground fault detection device 100, the breaker units 25a, 25b, and 25c are blocked. Accordingly, when the positive electrode bus 1 or the negative electrode bus 2 is grounded, it is possible to prevent an electric shock even if a person touches the positive electrode bus 1 or the negative electrode bus 2.

  In addition, according to the above configuration, when the first switch circuit 82 is turned on and the second switch circuit 84 is turned off, the ground fault of the negative electrode bus 2 can be detected, and the first switch circuit 82 is turned on, When the second switch circuit 84 is turned on, the ground fault of the positive bus 1 can be detected. In addition, when a ground fault occurs between the plurality of secondary batteries connected in series in the secondary battery units 30a, 30b, and 30c instead of the positive electrode bus 1 or the negative electrode bus 2, the above-described positive electrode bus 1 It is detected that a ground fault has occurred in both cases of detecting a ground fault and detecting a ground fault of the negative electrode bus 2. As a result, even if a ground fault occurs between the plurality of secondary batteries, the breakers 25a, 25b, and 25c are blocked, so that a person should be in contact with the positive electrode bus 1 or the negative electrode bus 2 by any chance. It is possible to prevent an electric shock even when touched.

  Note that an example in which a ground fault is detected in the power supply system 10 with the above configuration will be described with reference to FIG. FIG. 3 is a timing chart when the occurrence of a ground fault is detected when the positive electrode bus 1 has a ground fault.

  First, the first switch circuit 82 is turned on for 5 seconds to determine whether or not the negative electrode bus 2 is grounded. At this time, since the ground fault has not occurred in the negative electrode bus 2, the voltage signal that is the output signal of the low frequency filter 94 does not exceed the reference voltage value (threshold value). For this reason, the output of the comparator 95 also remains Low.

  Then, after 3 seconds have passed since the first switch circuit 82 was turned off, the second switch circuit 84 is turned on for 5 seconds to determine whether or not the positive bus 1 is grounded. At this time, a ground fault has occurred in the positive electrode bus 1, and the period in which the voltage signal of the low frequency filter 94 exceeds the threshold continues for 2 seconds or more. As a result, the determination circuit 99 determines that a ground fault has occurred, and changes the output signal to the control unit 70 from Low to High. Therefore, the control unit 70 that has received the output signal can shut off the breaker units 25a, 25b, and 25c as a countermeasure when a ground fault occurs.

  In addition, the detection of the ground fault by the said structure is performed about once per day, for example. In this case, the ground fault is preferably detected when both the charging switch circuit 402 and the discharging switch circuit 406 are on. Therefore, the ground fault detection can be retried by providing an opportunity to detect the ground fault at a predetermined interval (for example, 10 minutes). Specifically, when the ground switch can be detected when both the charging switch circuit 402 and the discharging switch circuit 406 are on, the ground fault detection for the day is terminated. When one of the charging switch circuit 402 and the discharging switch circuit 406 is on and the other is off, the ground fault is detected once in that state, and then the other The ground fault detection can be retried until the switch circuit is turned on.

  DESCRIPTION OF SYMBOLS 1 Positive electrode bus, 2 Negative electrode bus, 10 Electric power supply system, 20 Solar cell module, 25a, 25b, 25c Breaker part, 30a, 30b, 30c Secondary battery part, 40 Switching apparatus, 41a, 41b, 41c Switch circuit, 42a, 42b, 42c resistance element, 70 control unit, 75 load, 80 first resistance element, 82 first switch circuit, 84 second switch circuit, 86 second resistance element, 90 ground fault detection unit, 91 I / V conversion resistance Element, 92 High frequency filter, 93 Full wave rectifier circuit, 94 Low frequency filter, 95 Comparator, 96 Reference voltage circuit, 97 Resistance element, 98 Capacitance element, 99 Judgment circuit, 100 Ground fault detection device, 251, 253, 255 Positive side breaker, 252, 254, 256 Negative side breaker, 402 Switch circuit for charging 404 parallel processing circuit unit, 406 discharge switch circuit, 702 charge / discharge processing unit, 704 ground fault handling unit.

Claims (5)

A first switch circuit for connecting / cutting off the first path between the positive electrode bus connected to the positive electrode side of the secondary battery unit and the ground potential location;
A second switch circuit for connecting / blocking a second path between the negative electrode bus connected to the negative electrode side of the secondary battery unit and the ground potential portion;
A ground fault detection device, comprising: a ground fault detection unit that detects that the positive bus or the negative bus is grounded based on the current of the first path or the second path. The ground fault detection device according to claim 1,
The ground fault detection device detects the ground fault based on the current in a state where only one of the first path and the second path is connected. The ground fault detection device according to claim 2,
In the secondary battery unit, a plurality of secondary batteries are connected in series,
The ground fault detector is
Based on the current of the first path in a state where the first path is connected and the current of the second path in a state where the second path is connected, between the plurality of secondary batteries. A ground fault detection device characterized by detecting a ground fault. In the ground fault detection apparatus of any one of Claims 1-3,
The ground fault detector is
When detecting a ground fault, a ground fault detection device that outputs a signal for shutting off a cutoff circuit connected in series with the secondary battery unit. In the ground fault detection apparatus according to any one of claims 1 to 4,
The ground fault detector is
An I / V converter that converts the current of the first path or the current of the second path into a voltage value;
A comparator that compares the output value of the I / V converter with the predetermined threshold;
A determination unit that determines that a ground fault has occurred when a time during which an output value of the I / V conversion unit exceeds the predetermined threshold continues for a predetermined time;
A ground fault detection device comprising:

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