JP5407024B2 - Secondary battery system - Google Patents

Description

  The present invention relates to a secondary battery system that detects a ground fault position of an assembled battery using a secondary battery.

  2. Description of the Related Art Conventionally, an assembled battery system that uses an assembled battery composed of a plurality of single cells using a sodium-sulfur battery (hereinafter referred to as “NAS battery”) as a single cell is known. For example, such an assembled battery system is used for power storage at night. In the assembled battery system, when a ground fault occurs in any single battery, the ground fault is detected by the ground fault detection device. When a ground fault is detected, the assembled battery system is stopped and a recovery operation is performed.

On the other hand, various types of battery ground fault detection devices are known. For example, it is disclosed that a ground fault is detected by alternately switching between a positive electrode and a negative electrode of a battery and grounding through a resistor, and measuring a voltage in a grounded state to obtain a ground fault resistance (for example, , See Patent Document 1). Further, it is disclosed that in an assembled battery in which a plurality of battery groups in which secondary batteries are connected in series are connected in parallel, the batteries are sequentially opened for each row to determine the presence or absence of a ground fault in the closed battery group. (For example, see Patent Document 2).
JP-A-5-273287 JP 7-325121 A

  However, when the ground fault detection device described in Patent Document 1 is applied to the above-described battery assembly system, it takes time to identify the ground fault location, and the recovery of the battery assembly system is delayed. Become.

  On the other hand, in the ground fault detection apparatus described in Patent Document 2, a circuit breaker must be provided for each battery group in order to specify the ground fault location. Therefore, it cannot be applied when the circuit breaker cannot be provided due to restrictions such as the design of the assembled battery.

  Accordingly, an object of the present invention is to provide a secondary battery system that can quickly identify the ground fault position of an assembled battery using a secondary battery.

A secondary battery system according to an aspect of the present invention equally divides an assembled battery in which two or more secondary batteries are connected in series, and a line voltage between a positive electrode and a negative electrode of the assembled battery with an intermediate point as a boundary. A ground fault detecting means for detecting a ground fault based on a current flowing through the ground fault detecting resistor, and a ground fault detecting resistor for grounding the intermediate point by the two voltage dividing resistances; And when the current flowing through the ground fault detection resistor flows toward the ground side, the ground fault location is determined as the negative electrode side inside the battery assembly, and the current flowing through the ground fault detection resistor is directed toward the battery assembly side. The ground fault location is determined to be the positive side inside the assembled battery.

  ADVANTAGE OF THE INVENTION According to this invention, the secondary battery system which can identify quickly the ground fault position of the assembled battery using a secondary battery can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram showing a configuration of a secondary battery system 1 according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part in subsequent figures, the detailed description is abbreviate | omitted, and a different part is mainly described. In the following embodiments, the same description is omitted.

  The secondary battery system 1 includes an assembled battery 2, a ground fault detector 3, an AC / DC converter 5 connected to the assembled battery 2, and two interruptions connected between the assembled battery 2 and the AC / DC converter 5. And 4.

  The assembled battery 2 supplies DC power to the AC / DC converter 5 during the day and charges DC power from the AC / DC converter 5 at night.

  The assembled battery 2 has a configuration in which four battery groups P11 to P16, P21 to P26, P31 to P36, and P41 to P46 are connected in parallel.

  The battery groups P11 to P16 have a configuration in which six unit cells P11, P12, P13, P14, P15, and P16 are connected in series. The battery groups P21 to P26 have a configuration in which six unit cells P21, P22, P23, P24, P25, and P26 are connected in series. The battery groups P31 to P36 have a configuration in which six unit cells P31, P32, P33, P34, P35, and P36 are connected in series. The battery groups P41 to P46 have a configuration in which six unit cells P41, P42, P43, P44, P45, and P46 are connected in series.

  The cells P11 to P46 are high-temperature operation type NAS batteries that operate at around 300 ° C.

  The ground fault detection device 3 includes two voltage dividing resistors 31A and 31B, a ground fault detection resistor 32, a ground fault detector 33, a current direction determination circuit 34, and a display circuit 35.

  The two voltage dividing resistors 31 </ b> A and 31 </ b> B are connected in series between the positive electrode and the negative electrode of the assembled battery 2. The two voltage dividing resistors 31A and 31B have the same resistance value. Therefore, the voltage of the assembled battery 2 is equally divided at the intermediate point that is the connection point of the two voltage dividing resistors 31A and 31B. That is, the potential at the intermediate point is an intermediate potential between the positive electrode potential and the negative electrode potential of the assembled battery 2.

  The ground fault detection resistor 32 has one terminal connected to an intermediate point between the two voltage dividing resistors 31A and 31B, and the other terminal grounded.

  The ground fault detector 33 measures the current flowing through the ground fault detection resistor 32. A ground fault is detected when the amount of current flowing through the ground fault detection resistor 32 exceeds a predetermined value.

  The current direction determination circuit 34 determines the direction of the current flowing through the ground fault detection resistor 32. The current direction determination circuit 34 specifies the ground fault location of the assembled battery 2 based on the determined current direction.

  When the ground fault detector 33 detects a ground fault, the display circuit 35 displays that a ground fault has occurred. At this time, the display circuit 35 also displays the ground fault location specified by the current direction determination circuit 34 at the same time.

  The AC / DC converter 5 converts the DC power supplied from the assembled battery 2 into AC power during the daytime and supplies it to the load, and converts AC power received from the power system on the power source side into DC power during the night. Then, the assembled battery 2 is charged.

  The circuit breaker 4 opens and closes the connection between the AC / DC converter 5 and the assembled battery 2. The two circuit breakers 4 are provided on the positive electrode side and the negative electrode side, respectively. The circuit breaker 4 is turned on when the secondary battery system 1 is used. The circuit breaker 4 is opened when it is disconnected from the secondary battery system 1 when, for example, a fault such as a ground fault occurs in the assembled battery 2.

  Next, with reference to FIG. 2, the ground fault location specifying method by the ground fault detection device 3 will be described.

  FIG. 2 is a circuit diagram for explaining a method for identifying a ground fault location by the ground fault detection device 3 of the present embodiment.

  A point FG indicates a ground fault location. The power supply PP represents all the cells that are on the positive electrode side of the ground fault location. The power supply PN represents all the cells that are on the negative electrode side of the ground fault location. The ground fault resistance GR represents the electrical resistance of the grounded location.

  For example, when the ground fault location has a ground fault between the unit cell P11 and the unit cell P12 shown in FIG. 1, the power source PP represents the unit cell P11, and the power source PN represents the unit cells P12 to P16. .

  Here, the voltage of the power source PP is e1, the voltage of the power source PN is e2, the resistance values of the voltage dividing resistors 31A and 31B are R, the resistance value of the ground fault resistor GR is r, the ground fault detection resistor 32 is R0, and the power source PP side The current flowing through the closed circuit is IG1, and the current flowing through the closed circuit on the power source PN side is IG2.

  At this time, the following equation is derived.

IG1 = e1 / (R + R0 + r) Formula (1)
IG2 = e2 / (R + R0 + r) Formula (2)
From the equations (1) and (2), the following equation is derived.

e1 / IG1 = e2 / IG2 Formula (3)
From the equation (3), the following can be understood.

  When the current direction of the ground fault detection resistor 32 is IG1 (when the current flows toward the ground side), since IG1> IG2, e1> e2. This indicates that the number of single cells located on the positive electrode side than the ground fault location is larger than the number of single cells located on the negative electrode side.

  Accordingly, the grounded unit cell is specified as one of the unit cells P14 to P16, P24 to P26, P34 to P36, and P44 to P46 in the range GN belonging to the negative electrode side.

  On the other hand, when the current direction of the ground fault detection resistor 32 is IG2 (when the current flows toward the assembled battery 2 side), since IG1 <IG2, e1 <e2. This indicates that the number of single cells located on the positive electrode side than the ground fault location is smaller than the number of single cells located on the negative electrode side.

  Therefore, the unit cell having a ground fault is specified as one of the unit cells P11 to P13, P21 to P23, P31 to P33, and P41 to P43 in the range GP belonging to the positive electrode side.

  According to the present embodiment, in the assembled battery system 1, the ground fault detection device 3 can quickly identify the ground fault location.

  Moreover, since it is not necessary to provide a circuit breaker, a changeover switch, etc. in order to detect a ground fault, the ground fault detection apparatus 3 can be used for various assembled battery systems, and is excellent in versatility.

  Furthermore, when detecting a ground fault, the ground fault detection device 3 does not need to perform a special operation (such as opening / closing of a circuit breaker or switching of a changeover switch), and thus can detect a ground fault immediately. .

  In the present embodiment, the assembled battery 2 has been described as having 24 single cells, but the present invention is not limited to this. The battery group constituting the assembled battery 2 may connect any number of unit cells in series. Any number of battery groups may be connected in parallel.

  In this embodiment, a NAS battery is used as the secondary battery, but other batteries may be used.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the structure of the secondary battery system 1 which concerns on embodiment of this invention. The circuit diagram for demonstrating the identification method of the ground fault location by the ground fault detection apparatus 3 of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Secondary battery system, 2 ... Collective battery, 3 ... Ground fault detection apparatus, 4 ... Circuit breaker, 5 ... AC / DC converter, 31A, 31B ... Voltage dividing resistance, 32 ... Ground fault detection resistance, 33 ... Ground fault detection 34, current direction determination circuit, 35 ... display circuit.

Claims (6)

An assembled battery in which two or more secondary batteries are connected in series;
Two voltage dividing resistors that equally divide the line voltage between the positive electrode and the negative electrode of the battery assembly at an intermediate point;
A ground fault detection resistor for grounding the intermediate point by the two voltage dividing resistors;
Ground fault detection means for detecting a ground fault based on the current flowing through the ground fault detection resistor;
When the current flowing through the ground fault detection resistor flows toward the ground side, the ground fault location is determined as the negative electrode side inside the battery assembly, and the current flowing through the ground fault detection resistor flows toward the battery assembly side. And a ground fault location determination means for determining a ground fault location as the positive electrode side inside the assembled battery. The secondary battery system according to claim 1, further comprising a ground fault display unit that displays that a ground fault has occurred when a ground fault is detected by the ground fault detection unit. The secondary battery system according to claim 2, further comprising a ground fault location display unit configured to display the ground fault location when the ground fault location is determined by the ground fault location determination unit. A ground fault detection device for detecting a ground fault of a secondary battery system including an assembled battery in which two or more secondary batteries are connected in series,
Two voltage dividing resistors that equally divide the line voltage between the positive electrode and the negative electrode of the battery assembly at an intermediate point;
A ground fault detection resistor for grounding the intermediate point by the two voltage dividing resistors;
Ground fault detection means for detecting a ground fault based on the current flowing through the ground fault detection resistor;
When the current flowing through the ground fault detection resistor flows toward the ground side, the ground fault location is determined as the negative electrode side inside the battery assembly, and the current flowing through the ground fault detection resistor flows toward the battery assembly side. A ground fault detection device for a secondary battery system, comprising: a ground fault location determination unit that determines a ground fault location as a positive electrode side inside the assembled battery. 5. The ground fault detection device for a secondary battery system according to claim 4, further comprising ground fault display means for displaying that a ground fault has occurred when a ground fault is detected by the ground fault detection means. The ground fault detection of the secondary battery system according to claim 4, further comprising a ground fault location display unit that displays the ground fault location when the ground fault location is determined by the ground fault location determination unit. apparatus.

Images