JP5188370B2 - Battery system - Google Patents

Description

  The present invention relates to a battery system in which a plurality of battery cells and a fuse are connected in series, and more particularly to a battery system capable of detecting an excessive current exceeding the maximum detection current of a current detection circuit.

A battery system in which a fuse is connected in series with a battery has been developed (see Patent Documents 1 and 2). In this battery system, when an overcurrent flows through the battery, the fuse is blown to protect the battery from the overcurrent. In a battery system mounted on a vehicle such as a hybrid car, the current supplied from the battery to the motor varies greatly depending on the traveling state of the vehicle. When the vehicle is accelerated rapidly, a large discharge current flows from the battery to the motor, a large charging current flows to the battery in the regenerative braking of the sudden brake, and no current flows to the battery when the motor does not assist driving. Thus, in a battery system mounted on a hybrid car or the like, the current for charging / discharging the battery varies greatly. For this reason, fuses are connected in series to protect the battery from overcurrent. This fuse generates heat due to the Joule heat of the flowing current and blows off to interrupt the current. The amount of heat generated by Joule heat of the fuse is proportional to the product of the square of the current, the electrical resistance, and time. For this reason, when a large current flows, the fuse is heated to a high temperature with a large Joule heat and blown. In a state where no current flows, the heat is radiated without being heated. In the state where the current fluctuates, the fuse is repeatedly heated and dissipated, and the generated Joule heat greatly fluctuates. Therefore, it is necessary that the fuse has a specification that does not easily blow in the operating current range and a specification that blows with an excessive current such as an external short circuit. However, a failure state such as an external short circuit may be caused by a short circuit with a specific resistance value. For this reason, the fuse may not be blown in a state where an excessive current that damages the battery flows.
JP 2003-169401 A JP 2001-327001 A

  The battery system described in the patent document can detect the blow of the fuse, but cannot protect the battery from an excessive current that does not blow the fuse. The battery system detects a current of a battery to be charged / discharged by connecting a current detection resistor in series with the battery. For example, a battery system mounted on a hybrid car detects the voltage of the current detection resistor so that the battery current can be detected in a range of ± 200 A. This battery system detects the current with high accuracy by integrating the charged and discharged current and calculating the remaining capacity. This current detection circuit limits the current detection range to the aforementioned range in order to detect current with high accuracy. Therefore, the excessive current that blows the fuse is outside the detection range of the current detection circuit, and the excessive current cannot be detected. For this reason, the conventional battery system cannot detect a state in which an excessive current that damages the battery flows and the fuse is not blown. For example, in the battery system described above, an excessive current exceeding ± 200 A that allows charging and discharging of the battery, and an excessive current that does not blow the fuse cannot be detected. Since this excessive current damages the battery, the safety of the battery can be improved by detecting that this excessive current has flowed.

  The present invention has been developed for the purpose of realizing this. An important object of the present invention is to provide a battery system capable of detecting an excessive current outside a detection range that cannot be detected by a current detection circuit while having a very simple circuit configuration.

Means for Solving the Problems and Effects of the Invention

The battery system according to the present invention includes a battery unit 1, 31 formed by connecting a plurality of rechargeable battery cells 2, a fuse 3, and a current detection resistor 4 at a connection point 7, and connecting the battery units 1, 31 in series. The voltage detection circuit 5 that detects the voltage of each battery cell 2 that constitutes the battery, the current detection circuit 6 that detects the current of the battery unit 1 by detecting the voltage of the current detection resistor 4, and the outputs of the battery units 1 and 31 And a contactor 9 provided on the side . Battery system further includes a resistor circuit 8 including a series circuit of a fuse 3 and the current detection resistor 4, the voltage detection circuit 5 for detecting a voltage of the battery cell 2, by detecting the voltage of the resistor circuit 8, the current An excessive current outside the detection range that is larger than the maximum current that can be detected by the detection circuit 6 is detected , and the contactor 9 is turned off when the voltage detection circuit 5 detects an excessive current exceeding a preset set value. The

  The battery system described above is characterized by being able to detect an excessive current outside the detection range that cannot be detected by the current detection circuit while having a very simple circuit configuration. For this reason, the battery system described above improves battery safety by detecting the excessive current even when excessive current that damages the battery flows and the fuse is not blown, which cannot be detected by the current detection circuit. There are features that can be done. Since an excessive current outside the detection range that cannot be detected by the current detection circuit can be detected, even when the fuse is not blown, control such as stopping subsequent use of the battery at the magnitude of the detected current can be realized.

The battery system of the present invention, a resistor circuit 8 may be a current series circuits of the detection resistor 4 and the fuse 3. The battery system that detects the voltage of the current detection resistor with the voltage detection circuit can accurately detect an excessive current outside the detection range. In addition, the battery system that detects the voltage of the fuse or the series circuit of the current detection resistor and the fuse can detect an excessive current outside the detection range, and can also detect a blown fuse.
Furthermore, in the battery system of the present invention, the resistance circuit 8 can include the battery cell 2.

  The battery system of the present invention can include an amplifier 11 that amplifies the voltage of the resistance circuit 8. This battery system can accurately detect an excessive current outside the detection range by amplifying a low voltage generated at both ends of the resistance circuit.

Furthermore, in the battery system of the present invention, the voltage detection circuit 5 includes a multiplexer 12 for switching the connection point 7 of the battery units 1 and 31 on the input side, and connects the output side of the amplifier 11 to the input side of the multiplexer 12. The multiplexer 12 switches between the output side of the amplifier 11 and the connection point 7 to detect the voltage of each battery cell 2 and the voltage of the resistance circuit 8 to detect an excessive current outside the detection range of the current detection circuit 6. Can do.
The above battery system can detect the voltage of the resistor circuit 8 by switching the multiplexer, and the amplifier 12 amplified by the amplifier is switched and detected by the multiplexer 12, so that an excessive current outside the detection range can be detected while making the circuit configuration extremely simple. It can be detected accurately.

In the battery system of the present invention, the voltage detection circuit 5 can detect the voltage at the connection point 7 with respect to the earth line 10 to detect the voltage of each battery cell 2 and the voltage of the resistance circuit 8.
In the battery system described above, the multiplexer can switch the input terminal on one side in order and detect the voltage of the battery cell and the voltage of the resistance circuit, so that the multiplexer can have a simple circuit configuration.

In the battery system of the present invention, the battery cell 2 can be a battery module formed by connecting a plurality of nickel metal hydride batteries in series.
This battery system can detect an excessive current outside the detection range while detecting the voltage of the battery module.

In the battery system of the present invention, the battery cell 2 can be either a lithium ion battery or a lithium polymer battery.
This battery system can detect an excessive current outside the detection range while detecting the voltage of each lithium ion battery or lithium polymer battery.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a battery system for embodying the technical idea of the present invention, and the present invention does not specify the battery system as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The battery system shown in FIGS. 1 and 2 is mounted on a vehicle such as a hybrid car, a fuel cell vehicle, and an electric vehicle, and drives a motor 22 connected as a load 20 to drive the vehicle. A motor 22 serving as a load 20 of the battery unit 1 is connected to the battery unit 1 via a DC / AC inverter 23. The DC / AC inverter 23 converts the direct current of the battery unit 1 into a three-phase alternating current, and controls the power supplied to the motor 22. The DC / AC inverter 23 is connected to a generator 24, and the battery unit 1 is charged with the power generated by the generator 24.

  The battery system in this figure detects a voltage of a battery unit 1 in which a plurality of rechargeable battery cells 2, a fuse 3 and a current detection resistor 4 are connected in series, and a battery cell 2 constituting the battery unit 1. A voltage detection circuit 5 and a current detection circuit 6 that amplifies the voltage of the current detection resistor 4 to detect the battery current are provided.

  The battery unit 1 supplies power to the DC / AC inverter 23 on the vehicle side via the contactor 9, and supplies power to the motor 22 from the DC / AC inverter 23. In order to supply a large amount of power to the motor 22, the battery unit 1 has a large number of rechargeable battery cells 2 connected in series to increase the output voltage. The battery cell 2 is a nickel metal hydride battery, a lithium ion battery, or a lithium polymer battery. The battery unit 1 in which the battery cell 2 is a nickel metal hydride battery connects a plurality of nickel metal hydride batteries in series to form a battery module, the battery module is the battery cell 2, and the voltage detection circuit 5 detects the voltage of each battery module. . A battery unit having a battery cell as a lithium ion battery or a lithium polymer battery detects the voltage of each lithium ion battery or lithium polymer battery with a voltage detection circuit.

  In the battery unit 1, each battery cell 2, the current detection resistor 4, and the fuse 3 are connected at a connection point 7 and are connected in series with each other. The battery unit 1 has an output voltage of 100 to 400 V, for example, depending on the number of connected battery cells 2 so that large power can be supplied to the motor 22. However, since the battery system can boost the voltage of the battery unit and supply power to the load, the number of battery cells connected in series can be reduced and the output voltage of the battery unit can be lowered.

  The battery system of FIG. 1 divides the battery unit 1 into a first block 1A and a second block 1B, and the first block 1A and the second block 1B are connected via a series circuit of a current detection resistor 4 and a fuse 3. Connected in series. In this battery system, the connection point 7 between the current detection resistor 4 and the battery cell 2 is an intermediate line between the first block 1A and the second block 1B. In this battery system, the current detection resistor 4 and the fuse 3 are connected between the first block 1A and the second block 1B. However, the current detection resistor and the fuse can be connected to the positive and negative output sides. . Moreover, it can also connect between the battery cells which comprise the 1st block and the 2nd block.

  In the battery system of FIG. 2, the battery unit 31 is configured by a set of battery blocks, and the negative side is the ground line 10. Further, the current detection resistor 4 and the fuse 3 are connected to the negative side of the battery unit 31. Although not shown, in the battery system, the current detection resistor and the fuse can be connected to the plus side, and the current detection resistor and the fuse can be connected to the plus side and the minus side.

  The current detection circuit 6 includes an amplifier 11 that amplifies a voltage induced in the current detection resistor 4 in a current range that allows charging and discharging of the battery. The amplifier 11 is a differential amplifier 11 </ b> A in which a pair of input terminals are connected to both ends of the current detection resistor 4. The differential amplifier 11 </ b> A amplifies a voltage generated at both ends of the current detection resistor 4 when a current flows, and outputs the amplified voltage to the multiplexer 12. The amplification factor of the differential amplifier 11A is specified from the electric resistance of the current detection resistor 4, the maximum current to be detected, and the maximum input voltage of the A / D converter 13. For example, when the electric resistance of the current detection resistor 4 is 0.5 mΩ, the maximum current detected by the current detection circuit 6 is ± 200 A, and the maximum input voltage of the A / D converter 13 is ± 5 V, the amplification factor of the differential amplifier 11 A Is 50. The differential amplifier 11A amplifies a voltage of 100 mV induced by flowing a current of 200 A through the current detection resistor 4 to 5 V and outputs the amplified voltage to the A / D converter 13. The current detection circuit 6 amplifies the voltage of the current detection resistor 4 by the differential amplifier 11A, inputs it from the multiplexer 12 to the A / D converter 13, converts it to a digital signal by the A / D converter 13, and supplies it to the arithmetic circuit 14. Calculate to detect current. The arithmetic circuit 14 calculates the voltage / electric resistance of the current detection resistor 4 to detect a current.

  The voltage detection circuit 5 detects the voltage of each battery cell 2 by detecting the voltage at the connection point 7 and also detects the voltage of the resistance circuit 8 including at least one of the current detection resistor 4 and the fuse 3. An excessive current outside the detection range that is larger than the maximum current that can be detected by the current detection circuit 6 is detected. The battery system shown in FIGS. 1 and 2 uses the resistor circuit 8 as a series circuit of the current detection resistor 4 and the fuse 3 to detect the voltage of the resistor circuit 8 and detect an excessive current outside the detection range. However, the current detection circuit can also detect an excessive current outside the detection range of the current detection circuit by detecting the voltage of the current detection resistor or fuse by using the resistance circuit as a current detection resistor or fuse. As shown in FIGS. 1 and 2, the battery system in which the resistance circuit 8 is a series circuit of the current detection resistor 4 and the fuse 3 is the fuse 3 and the current detection resistor necessary for detecting the voltage of the battery cell 2. 4 can detect an excessive current out of the detection range. For this reason, an excessive current outside the detection range that cannot be detected by the current detection circuit 6 can be detected with the circuit configuration for detecting the voltage of the battery cell 2 as it is.

  The voltage detection circuit 5 shown in FIGS. 1 and 2 switches the connection point 7 to detect the voltage of the battery cell 2 and the voltage of the resistance circuit 8, and the A / P connected to the output side of the multiplexer 12. A D converter 13, an arithmetic circuit 14 that calculates a digital signal output from the A / D converter 13, and a data transmission unit 15 that transmits information calculated by the arithmetic circuit 14 to the vehicle side. Further, an amplifier 11 for amplifying the voltage of the current detection resistor 4 which is the resistor circuit 8 is provided. The output of the amplifier 11 is input to the multiplexer 12, and the voltage of the current detection resistor 4 is detected.

  In the battery system of FIGS. 1 and 2, the output of the differential amplifier 11A is input to one input terminal of the multiplexer 12, and the A / D converter 13 and the arithmetic circuit 14 constituting the voltage detection circuit 5 are connected to the current detection circuit 6. It is used together. The multiplexer 12 switches the output of the differential amplifier 11 </ b> A and the connection point 7 of the battery unit 1 in order at a predetermined cycle and outputs the result to the A / D converter 13. The voltage detection circuit 5 detects the output of the differential amplifier 11A with respect to the earth line 10 to detect the current of the battery, and also detects the voltage at each connection point 7 with respect to the earth line 10 to detect the voltage of the battery cell 2. Then, an excessive current outside the detection range that cannot be detected by the current detection circuit 6 is detected.

  The A / D converter 13 converts an analog signal that is a voltage signal output from the multiplexer 12 into a digital signal and outputs the digital signal to the arithmetic circuit 14. The arithmetic circuit 14 calculates the voltage of the battery cell 2 from the digital voltage signal output from the A / D converter 13. The voltage of the battery cell 2 is calculated from the voltage difference between the positive and negative connection points 7 of each battery cell 2. The arithmetic circuit 14 detects an excessive current outside the detection range that cannot be detected by the current detection circuit 6 from the voltage of the resistance circuit 8. The arithmetic circuit 14 detects an excessive current outside the detection range from the electrical resistance of the resistance circuit 8, which is a series circuit of the current detection resistor 4 and the fuse 3, and the voltage of the resistance circuit 8. The arithmetic circuit 14 calculates [voltage of the resistance circuit 8] / [electric resistance of the resistance circuit 8] to detect an excessive current outside the detection range that cannot be detected by the current detection circuit 6. Since the electric resistance of the current detection resistor 4 and the fuse 3 is small, the electric resistance of the series circuit which is the resistor circuit 8 is also small. Therefore, even if an excessive current outside the detection range, for example, a very large current of 500 A, which cannot be detected by the current detection circuit 6 flows through the battery, it is induced in the resistance circuit 8 that is a series circuit of the current detection resistor 4 and the fuse 3. The voltage is small, and an excessive current outside the detection range is detected from this voltage. For example, in a battery system in which the electric resistance of the series circuit of the current detection resistor 4 and the fuse 3 is 1 mΩ, when an excessive current of 2000 A flows through the battery, the voltage induced in the resistor circuit 8 becomes 2V. Therefore, in the battery system using the A / D converter 13 that can convert the voltage range of ± 5 V into a digital signal, an excessive current outside the detection range up to 5000 A can be detected.

  Further, as shown in the figure, the voltage of the resistor circuit 8 is divided by the voltage dividing resistor 16 and is input from the multiplexer 12 to the A / D converter 13, whereby a larger excessive current can be detected. Further, even in a battery system in which the resistance of a resistor circuit composed of a series circuit of a current detection resistor and a fuse increases and the voltage of the resistor circuit with respect to an excessive current increases, the voltage of the resistor circuit is divided into an A / D converter. By inputting, it is possible to detect an excessive current outside a detection range that is considerably large and cannot be detected by the current detection circuit.

  Therefore, in the battery system of FIGS. 1 and 2, an excessive current that cannot be detected by the current detection circuit 6 flows to the battery, and the current detected from the voltage of the current detection resistor 4 in a state where the fuse 3 is not blown. The battery current can be controlled by specifying the damage of the battery. For example, when it is detected that an excessive current exceeding a preset value has flowed, the contactor 9 is switched off in a state where the fuse 3 is not blown, and charging / discharging of the battery is stopped, or via the data transmission unit 15 Then, a signal for stopping charging / discharging of the battery is transmitted to the vehicle side to stop charging / discharging of the battery.

1 is a circuit diagram of a battery system according to an embodiment of the present invention. It is a circuit diagram of the battery system concerning the other Example of this invention.

Explanation of symbols

1 ... Battery part 1A ... 1st block
DESCRIPTION OF SYMBOLS 1B ... 2nd block 2 ... Battery cell 3 ... Fuse 4 ... Current detection resistor 5 ... Voltage detection circuit 6 ... Current detection circuit 7 ... Connection point 8 ... Resistance circuit 9 ... Contactor 10 ... Earth line 11 ... Amplifier 11A ... Differential amplifier DESCRIPTION OF SYMBOLS 12 ... Multiplexer 13 ... A / D converter 14 ... Arithmetic circuit 15 ... Data transmission part 16 ... Voltage dividing resistor 20 ... Load 22 ... Motor 23 ... DC / AC inverter 24 ... Generator 31 ... Battery part

Claims (7)

A battery unit (1), (31) in which a plurality of rechargeable battery cells (2), a fuse (3) and a current detection resistor (4) are connected at a connection point (7) and connected in series. Battery part (1), a voltage detection circuit (5) for detecting the voltage of each battery cell (2) constituting the (31), and a battery part (1) by detecting the voltage of the current detection resistor (4) A battery system comprising a current detection circuit (6) for detecting the current of (31) and a contactor (9) provided on the output side of the battery unit (1), (31) ,
Furthermore, a resistance circuit including a series circuit of at least the fuse (3) and the current detection resistor (4),
The voltage detection circuit for detecting the voltage of the battery cell (2) (5), wherein by detecting the voltage of the resistor circuit (8), the current detection circuit (6) is out of a large detection range than the maximum current that can be detected Ri name so as to detect the excessive current,
Battery System The contactor (9), an excessive current exceeding the set value which is set in advance when detecting the voltage detection circuit (5), characterized in that it is turned off.   The battery system according to claim 1, wherein the resistance circuit (8) includes a battery cell (2).   The battery system according to claim 1, further comprising an amplifier (11) for amplifying the voltage of the resistance circuit (8). The voltage detection circuit (5) includes a multiplexer (12) for switching the connection point (7) of the battery units (1) and (31) on the input side, and the amplifier (11) includes a multiplexer (12 12) is connected to the input side, the multiplexer (12) switches between the output side of the amplifier (11) and the connection point (7), the voltage of each battery cell (2), the resistance circuit (8) The battery system according to claim 3 , wherein an excessive current outside the detection range of the current detection circuit (6) is detected by detecting the voltage of the current. Wherein the voltage detection circuit (5), in claim 4 for detecting the voltage and the voltage of the resistor circuit (8) for detecting and each battery cell voltage at the connection point (7) (2) with respect to a ground line (10) The battery system described.   The battery system according to claim 1, wherein the battery cell (2) is a battery module formed by connecting a plurality of nickel metal hydride batteries in series.   The battery system according to claim 1, wherein the battery cell (2) is one of a lithium ion battery and a lithium polymer battery.

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