JP2009213196A - Device for adjusting capacity of battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for adjusting the capacity of a battery pack, which can accurately detect the temperature of a switching circuit element due to be protected. <P>SOLUTION: In the device for adjusting the capacity of the battery pack, which is equipped with a resistor 71 for capacity adjustment that is connected in parallel with one or more batteries 11 constituting the battery pack 1 and the switching circuit element 72 that is connected in series to the resistor 71 for capacity adjustment and controls a current for capacity adjustment flowing to the resistor for capacity adjustment, a thermosensitive resistor element 73 is provided between the drive terminal of the switching circuit element 72 and one terminal of the switching circuit element concerned where the current for capacity adjustment flows. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an assembled battery capacity adjustment device.

  In an assembled battery in which a plurality of batteries are connected, if charge / discharge is repeated or left unattended, a capacity difference (remaining capacity difference) may occur due to variations in characteristics of each battery. When an assembled battery is used in a state where a capacity difference has occurred, depending on the battery, overcharging or overdischarging occurs, and the life of the entire assembled battery is shortened. For this reason, the capacity | capacitance of each battery is equalized by discharging the battery with a capacity | capacitance larger than others.

Such capacity adjustment is performed by flowing a current from a battery having a larger capacity than the others to a capacity adjustment resistor included in a capacity adjustment circuit provided in parallel with each battery. There is a possibility that a capacitance adjusting circuit element such as a transistor included in the adjusting circuit is adversely affected.

Patent Document 1 discloses a protection circuit that prevents overcharging of a secondary battery by providing a temperature-sensitive resistor element in the battery power circuit.

Japanese Utility Model Publication No. 6-31345

In Patent Document 1, a temperature-sensitive resistance element whose resistance increases as the temperature rises is provided on a power supply circuit, and by thermally coupling the temperature-sensitive resistance element and a transistor as a capacitance adjusting circuit element, When the temperature of the transistor rises, the resistance of the temperature sensitive resistance element is increased to suppress the current flowing from the power source to the transistor. If such a circuit is applied, the current flowing through the transistor is suppressed by increasing the resistance of the temperature-sensitive resistance element provided on the power supply circuit when the temperature of the transistor to be protected increases, thereby preventing further increase in the temperature of the transistor. The transistor as a protection target can be protected.

However, in a protection circuit in which a temperature-sensitive resistor element is provided in a battery power supply circuit, the temperature-sensitive element is provided on the power supply circuit and the transistor is provided on the control circuit. Unlike the actual temperature of the transistor to be protected, there is a problem that the protection target element such as a transistor cannot be properly protected.

The problem to be solved by the present invention is to provide an assembled battery capacity adjustment device capable of accurately detecting the temperature of a switching circuit element to be protected and reliably protecting the switching circuit element.

The present invention solves the above problem by providing a temperature-sensitive resistance element between the drive terminal of the switching element and one terminal through which the capacity adjustment current flows.

  According to the present invention, it is possible to accurately detect the temperature of the switching circuit element to be protected.

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

FIG. 1 is a block diagram showing an assembled battery system including a capacity adjustment device 7 according to this embodiment. The assembled battery 1 shown in the figure has a plurality of batteries 11 connected in series and an inverter 2 connected to both electrodes via a power supply line 9. The direct current supplied from the assembled battery 1 is converted into an alternating current by an inverter 2 that is a power converter and supplied to the alternating current motor 3 to drive the alternating current motor 3. In the figure, reference numeral 4 denotes a current detection sensor that detects a current flowing through the power supply line 9, and the detected current value is sent to the overall control device 6 that controls the entire assembled battery. Reference numeral 5 denotes a voltage detection sensor that detects a voltage across the terminals of the assembled battery 1, and the detected voltage value is sent to the overall control device 6. The overall control device 6 controls the inverter 2 based on the output current of the assembled battery 1 detected by the current sensor 4 and the voltage of the assembled battery 1 detected by the voltage sensor 5, and when the assembled battery 1 is overdischarged In the case of limiting the output power of the assembled battery 1 or overcharging, the input power of the assembled battery 1 is limited, and the capacity adjustment control circuit 75 is controlled to adjust the capacity of each battery 11. Details will be described later.

FIG. 5 is a perspective view showing the control circuit board 8 according to the present embodiment. The capacitance adjustment resistor 71 shown in FIG. 1, the integrated circuit chip 76 in which the capacitance adjustment control circuit 75 is built, and the overall control device 6 are shown. The integrated circuit chip 61 in which the battery pack is built is mounted on a printed wiring board 81, and the control circuit board 8 is attached to a predetermined location of a battery pack (not shown) in which the assembled battery 1 is housed. In addition, 82 in FIG. 5 is a connector, and each chip on the control circuit board 8 is connected to each battery 11 via this connector.

In FIG. 5, an integrated circuit chip 76 is provided corresponding to each capacitance adjusting resistor 71. However, since the plurality of integrated circuit chips 76 are functionally identical, they may be handled as one block. Therefore, in FIG. 1, the capacity adjustment control circuit 75 and the integrated circuit chip 76 are represented by one block.

Moreover, the assembled battery system shown in FIG. 1 is an example for demonstrating the capacity | capacitance adjustment apparatus 7 which concerns on this embodiment, Comprising: The some battery 11 is connected in series like this example, and the assembled battery 1 is comprised. In addition to the above, the assembled battery 1 may be configured by connecting a plurality of batteries 11 in series and / or in parallel. Further, when the power supply target of the assembled battery 1 is a DC motor, the inverter 2 can be omitted, and the power supply target can be a load other than the motor 3.

Returning to FIG. 1, each battery 11 is connected with a capacitance adjusting resistor 71 in parallel. A switching circuit element 72 made of an npn-type bipolar transistor is connected in series with the capacitance adjusting resistor 71. And a switching circuit element 72 form a capacity adjustment circuit, and the capacity adjustment circuit is connected in parallel with each battery 11. When the capacitance adjustment control circuit 75 causes an ON current to flow through the base of the npn-type bipolar transistor constituting the switching circuit element 72 for a predetermined time t (a predetermined voltage is applied between the base and the emitter), the transistor 72 is turned on. Thus, a current flows from the battery 11 to the capacity adjustment resistor 71 for a predetermined time t (referred to as capacity adjustment time), and this discharge causes the capacity of the battery 11 (that is, the remaining capacity of the battery 11, hereinafter simply referred to as capacity). ) Adjustments are made.

More specifically, the capacity adjustment control circuit 75 detects the open voltage of each battery 11 and transmits it to the overall control device 6, and the overall control device 6 determines the minimum open voltage among the open voltages of each battery 11 and each battery. The difference with the open circuit voltage of 11 is calculated. Since the open voltage of the battery has a correlation with the capacity of the battery, the overall control device 6 determines whether each battery 11 and the battery with the minimum open voltage are based on the difference between the open voltage of each battery 11 and the minimum open voltage. A capacity difference is calculated, and a capacity adjustment time, which is a time for passing a current through the capacity adjustment resistor 71 connected in parallel to each battery 11 to discharge the calculated capacity difference, is calculated and transmitted to the capacity adjustment control circuit 75. . The capacity adjustment control circuit 75 supplies an ON current to the base of the bipolar transistor for the capacity adjustment time sent from the overall control device 6, and the capacity of each battery 11 is set to the capacity of the battery 11 having the lowest capacity (that is, the open circuit voltage is minimum). By matching, the capacity of each battery 11 is made uniform. At this time, the current flowing through the capacitance adjusting resistor 71 is referred to as a capacitance adjusting current.

The switching circuit element 72 according to the present embodiment can use a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT) in addition to an npn bipolar transistor. In addition to providing one capacity adjustment resistor 71 for one battery 11, the capacity adjustment of the assembled battery 1 may be performed by providing one capacity adjustment resistor 71 for a plurality of batteries 11. it can.

In particular, in this example, a temperature-sensitive resistance element 73 is provided together with a voltage dividing resistor 74 between the base and emitter of the bipolar transistor constituting the switching circuit element 72. The temperature-sensitive resistance element 73 is an electrical resistor that reacts to a temperature change, and is an NTC (Negative Temperature Coefficient) thermistor having a negative temperature characteristic in which a resistance value decreases as the temperature rises, that is, a negative temperature coefficient. . Examples of the temperature sensitive resistance element 73 having negative temperature characteristics include those obtained by mixing and sintering oxides such as nickel, manganese, cobalt, and iron.

When a field effect transistor is used as the switching circuit element 72 instead of the bipolar transistor, a temperature sensitive resistance element 73 is connected between the gate and drain of the FET together with a voltage dividing resistor.

In this example, when an ON current is passed through the base of the switching circuit element 72 by the capacitance adjustment control circuit 75, when the temperature sensitive resistance element 73 is below a predetermined temperature, a voltage corresponding to the resistance value of the temperature sensitive resistance element 73 is switched. Since it occurs between the base and emitter of the circuit element 72, an ON current flows from the capacity adjustment control circuit 75 to the base via the resistor 74, whereby the switching circuit element 72 is turned ON and the capacity adjustment resistor 71 is transferred from the battery 11. Current for capacity adjustment flows.

On the other hand, when the temperature-sensitive resistance element 73 is heated and becomes higher than a predetermined temperature, the resistance value of the temperature-sensitive resistance element 73 decreases, so that the voltage between the base and the emitter of the switching circuit element 72 decreases to that extent. As a result, the ON current does not flow from the capacitance adjustment control circuit 75 to the base of the switching circuit element 72.

  In this example, the function of the temperature-sensitive resistance element 73 is used to detect the temperature of the switching circuit element 72 with the temperature-sensitive resistance element 73, and when the switching circuit element 72 reaches a predetermined temperature or more, the base is used. The flowing ON current is cut off, thereby preventing the switching circuit element 72 from being overheated.

  For this reason, the temperature characteristic of the temperature-sensitive resistance element 73 is such that when the detected temperature of the switching circuit element 72 is substantially equal to or lower than the allowable limit temperature of the switching circuit element 72, the base of the switching circuit element 72 is It is desirable that the ON current to be cut off.

  More specifically, in the capacitance adjusting device 7 shown in FIG. 5, when a capacitance adjusting current flows through the capacitance adjusting resistor 71, the capacitance adjusting resistor 71 generates heat, and as shown in FIG. This heat is transmitted to the capacity adjustment control circuit chip 76 mounted in the vicinity. Since the transistor constituting the switching circuit element 72 in the capacity adjustment control circuit chip 76 has a limit in heat resistance, when the switching circuit element 72 reaches a predetermined temperature, it is used for capacity adjustment until it is cooled. It is desirable to temporarily cut off the current.

  However, in the technology using the temperature-sensitive resistor element disclosed in the conventional patent document 1, the temperature-sensitive resistor element is provided on the power supply circuit (on the high voltage circuit), and the transistor is on the control circuit (low voltage circuit). Therefore, it is necessary to secure a sufficient distance to ensure insulation between the high voltage circuit and the low voltage circuit. For this reason, when the technique disclosed in Patent Document 1 is applied as a protection circuit for a transistor (switching circuit element), the temperature of the transistor is difficult to be transmitted to the temperature-sensitive resistance element, and it is difficult to protect the transistor. there were. Furthermore, since the temperature sensitive resistance element is provided on the power supply circuit, the current flowing through the temperature sensitive resistance element is large and the temperature sensitive resistance element itself generates heat, so that the resistance of the temperature sensitive resistance element depends only on the temperature of the transistor. There was also a problem that it was difficult to change.

  For this reason, in this example, the electric circuit element indicated by reference numeral 76 in FIG. That is, by forming the temperature-sensitive resistance element 73 as a semiconductor integrated circuit component together with the switching circuit element 72, the actual temperature of the switching circuit element 72 is directly transmitted to the temperature-sensitive resistance element 73. Can be detected. Further, since the current flowing through the temperature-sensitive resistance element 73 is only a small control current for driving the switching circuit element 72, heat generation due to the current flowing through the temperature-sensitive resistance element 73 is small. Thereby, since the actual temperature of the switching circuit element 72 can be accurately detected by the temperature-sensitive resistance element 73, it is not necessary to perform extra processing such as temperature correction.

  Even if the temperature-sensitive resistance element 73 is not chipped together with the switching circuit element 72, the actual temperature of the switching circuit element 72 is almost directly set by arranging the temperature-sensitive resistance element 73 at a position in contact with or close to the switching circuit element 72. Therefore, it is possible to obtain the same effect as that of a chip.

  By the way, as described above, while the base current of the switching circuit element 72 is cut off using the temperature sensitive resistance element 73, the capacity adjustment process of the battery 11 is interrupted, and the target capacity adjustment between the batteries 11 is achieved. Will not be. However, in this example, even if the switching circuit element 72 is turned off in order to protect the switching circuit element 72, the target capacity adjustment processing can be continued.

  Specifically, as shown in FIG. 1, a voltage detection circuit 77 for detecting a voltage between both terminals of the capacitance adjustment resistor 71 is connected, and the voltage value detected by the voltage detection circuit 77 is used as a capacitance adjustment control circuit 75. To detect the ON / OFF state of the switching circuit element 72, in other words, the energization state in which the capacity adjustment current flows through the capacity adjustment resistor 71.

  That is, the capacitance adjustment control circuit 75 is based on the voltage value across the terminals of the capacitance adjustment resistor 71 sent from the voltage detection circuit 77, in other words, the time Ton when the switching circuit element 72 is in the ON state, in other words, The time Ton during which the capacity adjustment current flows through the capacity adjustment resistor 71 is integrated. When the integration time of the time Ton becomes the capacity adjustment time, the capacity adjustment is completed (the switching circuit element 72 is turned off), so that the target capacity adjustment processing can be executed even when the switching circuit element 72 is turned off. It has become.

When the current from the battery 11 flows through the capacity adjustment resistor 71, the voltage value detected by the voltage detection circuit 77 is lower than the voltage value when the current does not flow (equal to the voltage across the terminals of the battery 11). Thus, it can be determined whether or not the capacitance adjustment current is flowing through the capacitance adjustment resistor 71. By using a clock circuit or the like, the time during which the capacitance adjustment current flows can be integrated.

  In the capacity adjusting device 7 shown in FIG. 1, the voltage detecting circuit 77 is connected so as to detect the voltage between both terminals of the capacity adjusting resistor 71. However, other than this configuration, for example, in FIGS. A voltage detection circuit 77 can also be connected as shown.

  2 and 3 are main circuit diagrams showing a connection structure of a voltage detection circuit 77 according to another embodiment.

In the example shown in FIG. 2, the voltage detection circuit 77 is connected so that the voltage between the collector and emitter of the switching circuit element 72 is detected. According to this example, when the current from the battery 11 flows through the capacity adjustment resistor 71, the voltage value between the collector and the emitter detected by the voltage detection circuit 77 is the voltage value when the current does not flow (battery 11). Therefore, it is possible to determine whether or not a capacity adjustment current is flowing through the capacity adjustment resistor 71. When a field effect transistor FET is used as the switching circuit element 72, a voltage detection circuit 77 is connected so as to detect a voltage between terminals of the source and drain of the FET.

In the example shown in FIG. 3, the voltage detection circuit 77 is connected so that the voltage between the base and the emitter of the switching circuit element 72 is detected. According to this example, when the current from the battery 11 flows through the capacity adjustment resistor 71, the voltage value between the base and the emitter detected by the voltage detection circuit 77 is compared with the voltage value when not flowing. Therefore, it is possible to determine whether or not a capacity adjustment current is flowing through the capacity adjustment resistor 71. When a field effect transistor FET is used as the switching circuit element 72, a voltage detection circuit 77 is connected so as to detect a voltage between terminals of the gate and drain of the FET.

  FIG. 4 is a flowchart showing the operation of the capacity adjustment device 7 according to the present embodiment. The capacity adjustment operation including the case where the capacity adjustment is interrupted by the temperature-sensitive resistance element 73 will be described with reference to FIG.

  First, when it is detected in step ST10 that the assembled battery system is in the capacity adjustment mode, in step ST20, the capacity adjustment control circuit 75 detects the inter-terminal voltage of the battery 11 with a voltage detection circuit (not shown), and controls this. It is sent to the control circuit 6. The overall control circuit 6 compares the voltage between the terminals of each battery 11 sent from the capacity adjustment control circuit 75, and targets the adjustment capacity for each battery 11, specifically, the capacity adjustment current to flow to the capacity adjustment resistor 71. The capacity adjustment time T is calculated.

  Next, in step ST30, the overall control circuit 6 sends the calculated target capacity adjustment time T for each battery 11 to the capacity adjustment control circuit 75, and the capacity adjustment control circuit 75 switches the switching circuit element corresponding to each battery 11. The capacity adjustment processing is started by controlling the ON current to flow through the base 72 for the target capacity adjustment time T.

  In step ST40, the voltage detection circuit 77 shown in FIG. 1 detects the voltage between both terminals of the capacitance adjustment resistor 71 and sends it to the capacitance adjustment control circuit 75. The capacity adjustment control circuit 75 detects the ON / OFF state of the switching circuit element 72 based on the detected voltage value. In the subsequent step ST50, the ON time Ton of the switching circuit element 72, that is, the time Ton when the capacitance adjustment current flows through the capacitance adjustment resistor 71 is sequentially integrated.

  In step ST60, the time Ton when the accumulated capacity adjustment current flows is compared with the target capacity adjustment time T at predetermined time intervals, and it is determined whether or not the accumulation time Ton has reached the target capacity adjustment time T. To do. When the integration time Ton has not reached the target capacity adjustment time T, the capacity adjustment process is continued, and when the integration time Ton reaches the target capacity adjustment time T, the process proceeds to step ST60.

  In step ST60, it is determined whether or not the capacity adjustment process has been completed for all the batteries 11, and the processes of steps ST20 to ST60 are executed for the battery 11 that has not been completed.

  As described above, according to the capacity adjustment device of the present embodiment, when the switching circuit element 72 reaches a predetermined temperature due to the heat generated by the capacity adjustment resistor 71 during the capacity adjustment processing, the temperature-sensitive resistance element 73 reacts to switch the switching circuit element. 72 is turned OFF, and the heat generation of the capacitance adjusting resistor 71 is temporarily stopped. Thereby, overheating of the switching circuit element 72 can be prevented.

  Further, since the temperature-sensitive resistance element 73 directly detects the temperature of the switching circuit element 72, it is possible to accurately prevent the switching element 72 to be protected from being overheated to a predetermined temperature or higher. As a result, since the switching circuit element 72 can be operated up to the heat resistant limit temperature, the capacity adjustment can be performed in a short time without inadvertently interrupting the capacity adjustment process.

  Further, since the voltage detection circuit 77 detects the ON state of the switching circuit element 72 and the energization state of the capacity adjustment resistor 71 and compares the integrated time Ton with the target capacity adjustment time T, the assembled battery 1 is configured. The capacity of each battery 11 can be adjusted appropriately.

It is a block diagram which shows the assembled battery system provided with the capacity | capacitance adjustment apparatus which concerns on embodiment of this invention. It is an electric circuit diagram which shows the principal part of the capacity | capacitance adjustment apparatus which concerns on other embodiment of this invention. It is an electric circuit diagram which shows the principal part of the capacity | capacitance adjustment apparatus which concerns on further another embodiment of this invention. It is a flowchart which shows operation | movement of the capacity | capacitance adjustment apparatus which concerns on embodiment of this invention. It is a perspective view which shows the control circuit board which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Assembled battery 11 ... Battery 2 ... Inverter 3 ... Motor 6 ... Overall control device 61 ... Integrated circuit chip 7 of overall control device ... Capacity adjustment device 71 ... Capacity adjustment resistor 72 ... Switching circuit element 73 ... Temperature sensitive resistance element 74 ... Resistance 75 ... Capacity adjustment control circuit 76 ... Integrated circuit chip of capacitance adjustment control circuit 77 ... Voltage detection circuit 8 ... Control circuit board 9 ... Power supply line

Claims (7)

A set comprising a capacity adjustment circuit formed of a capacity adjustment resistor and a switching circuit element connected in series to the capacity adjustment resistor, connected in parallel to each of one or a plurality of batteries constituting the battery pack In the battery capacity adjustment device,
A battery pack capacity adjustment device, wherein a temperature-sensitive resistance element is provided between a drive terminal of the switching circuit element and one terminal connected to the negative electrode of the battery of the switching circuit element. The capacity adjustment apparatus for an assembled battery according to claim 1,
The temperature adjusting resistor element has a negative temperature characteristic in which resistance decreases as the temperature rises. In the capacity adjustment apparatus of the assembled battery according to claim 1 or 2,
Detecting means for detecting an ON / OFF state of the switching circuit element;
The battery pack capacity adjustment device further comprising: a control unit that controls the capacity adjustment based on the ON / OFF state detected by the detection unit. The capacity adjustment apparatus of the assembled battery according to claim 3,
The control means integrates the ON state time of the switching circuit element detected by the detection means, and executes the capacity adjustment control until the integration time reaches a capacity adjustment time. Battery pack capacity adjustment device. In the capacity adjustment apparatus of the assembled battery according to claim 1 or 2,
Detecting means for detecting an energization state in which the capacity adjusting current flows through the capacity adjusting resistor;
A battery pack capacity adjustment apparatus, further comprising: a control unit that controls the capacity adjustment based on an energization state of the capacity adjustment resistor detected by the detection unit. In the capacity adjustment apparatus of the assembled battery according to claim 5,
The control means integrates the time of energization state of the capacity adjustment resistor detected by the detection means, and executes the capacity adjustment control until the integration time reaches the capacity adjustment time. The capacity adjustment device of the assembled battery. In the capacity adjustment apparatus of the assembled battery as described in any one of Claims 3-6,
The detection means includes
Voltage of the capacitance adjusting resistor,
At least a voltage between terminals of the switching circuit element through which the capacity adjustment current flows, or a voltage between a driving terminal of the switching circuit element and one terminal of the switching circuit element through which the capacity adjustment current flows. Any one of them is detected, and the battery pack capacity adjustment device.

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