JP2005304276A - Battery management device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery management device that can perform discharging quickly to balance each battery 1 by enabling the discharge to be performed, even after the selection of each battery 1 is finished. <P>SOLUTION: A battery pack, which comprises a plurality of batteries 1 connected in series, is provided with a battery-selecting circuit that selects each battery 1 via a pulse transformer 3, based on battery selection signals and trigger signals form a microcomputer 4 and a battery voltage-detecting circuit that inputs the voltage of each battery 1 selected by this battery-selecting circuit to the microcomputer 4. Each battery 1 is provided with a discharging circuit 5 that discharges the batteries 1 selected by the battery selecting circuit and an integrating capacitor C<SB>I</SB>that discharges the batteries 1 by the discharging circuit 5, even after the selection of the batteries 1 is finished. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery management device that manages an assembled battery.

  For battery packs used in batteries such as electric vehicles and hybrid electric vehicles, the voltage of each battery connected in series is monitored by a microcomputer, and the battery management is balanced by discharging batteries with abnormally high voltages. An apparatus may be provided. A conventional configuration example of such a battery management apparatus is shown in FIG.

In this conventional example, each battery 1 consists of a nonaqueous electrolyte secondary battery, and many batteries 1 are connected in series. Each of these batteries 1 is connected to the primary winding of the pulse transformer 3 via the selection maintaining circuit 2. The selection maintaining circuit 2 operates as a blocking oscillator together with the pulse transformer 3, and the voltage of the battery 1 is applied to the primary winding of the pulse transformer 3 only when the FET _{1 of the} selection maintaining circuit 2 is ON. It has become. The pulse transformer 3 is an isolation transformer for insulating and transmitting the voltage of the battery 1 from the battery 1 side to the microcomputer 4 side.

One end of each secondary winding of the pulse transformer 3 connected to each battery 1 is grounded via the FET ₂ . The other end of the secondary winding of the pulse transformer 3 is connected to one analog input terminal A _IN of the microcomputer 4 collectively, the power supply V _DD through a single FET ₃ Connected and grounded through a single FET ₄ . Each FET ₂ has a gate terminal connected to a corresponding digital output terminal D _{1 to} D _n (n is the number of batteries 1) of the microcomputer 4, and the digital output terminals D _{1 to} D _n are at the H level (battery selection). Signal) is turned ON. Further, the FET ₃ is turned on when the digital output terminal _DT bar of the microcomputer 4 becomes L level (trigger signal), and the FET ₄ is turned on when the digital output terminal _DD becomes H level (discharge instruction signal). Become.

In the battery management device, the microcomputer 4 outputs _{one of the} digital output terminals D _{1 to} D _n to the H level and outputs a battery selection signal, thereby turning on the FET ₂ of the pulse transformer 3 connected to the corresponding battery 1. Thus, the battery 1 is selected. When two or more digital output terminals D _{1 to} D _n are simultaneously set to the H level, a plurality of batteries 1 are selected at the same time. When the microcomputer 4 selects the battery 1 and the digital output terminal _DT bar is set to L level for a short time to output a short pulse-like trigger signal, the FET ₃ is turned ON only during this period, and the selected battery is selected. A short-time current flows only in the secondary winding of one pulse transformer 3. Then, a voltage is induced in the primary winding of the pulse transformer 3, the selection maintaining circuit 2 of the selected battery 1 performs a single oscillation operation as a blocking oscillator, and a predetermined selection is made even after the trigger signal is not output. The ON state of FET ₁ lasts for the maintenance time. When FET _{1 of the} selection maintaining circuit 2 is turned on, FET ₂ is also turned on by the battery selection signal, so that the pulse transformer 3 transmits the voltage of the battery 1 to the analog input terminal _AIN of the microcomputer 4. To do. Therefore, when the microcomputer 4 outputs the trigger signal in a state where the battery 1 is selected, the voltage of the selected battery 1 is output from the analog input terminal _AIN during the selection maintaining time within the selection period after the trigger signal. Can be entered.

  The microcomputer 4 detects the voltages of these batteries 1 in order by outputting a trigger signal at the initial stage of each selection while sequentially selecting the batteries 1 of the assembled battery as described above. When all the batteries 1 have been selected in this way, the selection is performed again from the first battery 1 again, and the voltage of each battery 1 is monitored as needed by repeating this selection scanning process.

If the microcomputer 4 determines that the voltage of any battery 1 is abnormally high by detecting the voltage of the battery 1 in this manner, a trigger signal within the selection period of the abnormal battery 1 is detected. The digital output terminal _{DD is set} to the H level for a period sufficiently longer than the selection maintaining time immediately after the completion of the output, and a discharge instruction signal is output. Then, the FET ₄ is turned on while the discharge instruction signal is output, and the secondary side of the pulse transformer 3 of the selected battery 1 is grounded and short-circuited. Therefore, the selection is performed immediately after the trigger signal output is completed. The FET ₁ is turned ON only for the maintenance time, and a discharge current can flow from the battery 1 through the pulse transformer 3. Then, if this abnormal discharge process is performed only on the abnormal battery 1 during the selective scanning process for each battery 1, the voltage of the battery 1 decreases to a normal value as the selection operation process is repeated. It is possible to balance each battery 1 of the assembled battery. Since the voltage of the battery 1 cannot be detected during the discharge process, the battery 1 is selected and the trigger signal is output every time the selective scanning process is repeated, for example. What is necessary is just to judge that this voltage returned to normal by inserting the detection process of the normal voltage which does not output a discharge instruction | indication signal after completion suitably.

If the battery management device detects the voltage of each battery 1 only at the time of selection as described above, the path for inputting this voltage to the microcomputer 4 can be extremely reduced (in the example of FIG. The analog input terminal _AIN is sufficient), the number of A-D conversion circuits to be used can be greatly reduced, and even when the number of batteries 1 is large, the number of microcomputers 4 to be used is reduced. (In the example of FIG. 3, one microcomputer 4 is sufficient).

  However, since the conventional battery management apparatus discharges while the selective scanning process of the battery 1 is repeated in this way, only when the battery 1 is selected, the predetermined selection maintenance during the selection period is performed. Discharging is performed only in time, and during repetition of the selective scanning process, discharging is intermittently performed for a short time with a duty ratio smaller than a fraction of the number of all the batteries 1, There has been a problem that it takes a long time to perform the required amount of discharge.

  The present invention is intended to solve the problem that it takes a long time for discharging to balance each battery by allowing the discharge to be performed after each battery has completed selection.

  According to a first aspect of the present invention, in a battery management apparatus that manages an assembled battery in which a plurality of batteries are connected, a battery selection circuit that selects each battery based on a selection signal from a microcomputer, and each battery selected by the battery selection circuit A battery voltage detection circuit for inputting the voltage of the battery to the microcomputer, a battery discharge circuit for discharging the battery selected by the battery selection circuit for each battery, and the battery after the selection of the battery is completed. And a discharge maintaining circuit for discharging the discharge circuit.

  The invention according to claim 2 is characterized in that the discharge maintaining circuit maintains the discharge of the battery only for a predetermined discharge maintaining time after the selection of the battery is completed.

  According to the first aspect of the present invention, since the discharge maintaining circuit can discharge the battery with the battery discharge circuit after the selection of the battery is completed, the battery is selected regardless of the period during which the battery is selected, that is, the other battery is selected. It becomes possible to discharge over a long period of time even during the period during which the discharge is performed. For this reason, it is possible to quickly discharge a specific battery, and this does not hinder the process of detecting the voltage of another battery.

  The battery discharge circuit basically only needs to discharge when the microcomputer selects a battery and when a separate discharge is instructed. However, the battery discharge circuit always discharges when selecting the battery. You can also do it. In the case of always discharging when selecting a battery, all the batteries will be discharged during the repetition of the selective scanning process for detecting the voltage of each battery, but the number of batteries is large, By making the discharge after selection completion by the discharge sustaining circuit relatively short time, it is possible for each battery to be a short time discharge with a small duty ratio, so that almost no waste of power is caused by this. can do. In this case, in order to discharge one or a plurality of specific batteries, it is only necessary to temporarily interrupt the selective scanning process for all the batteries and select only these batteries simultaneously or sequentially. Even when the batteries are selected in order, the discharge of each battery is maintained during the selection period of the other batteries, so that the discharge can be performed quickly. In addition, the interruption time of the selective scanning process can also be shortened.

  Further, this battery discharge circuit may or may not discharge during the battery selection period. If no discharge is performed during the battery selection period, the discharge sustaining circuit discharges only after this selection.

  According to the invention of claim 2, the discharge of the battery is automatically stopped when the discharge maintaining time elapses after the selection is completed. Therefore, for example, when the discharge is always performed when the battery is selected, the discharge after the selection by the discharge maintaining circuit can be limited to a relatively short time. That is, when the discharge sustaining circuit is such that once it starts discharging, it is necessary to instruct to stop the discharge in order to limit this discharge to a relatively short time. If this discharge is limited to the discharge maintenance time, such an instruction to stop the discharge becomes unnecessary. In order to maintain the discharge permanently, it is necessary to continue supplying power to store this state in a flip-flop circuit or the like. However, if it is sufficient to maintain only the discharge maintenance time, for example, a transistor and an integration capacitor The discharge sustaining circuit can be configured with a simple circuit using the above. Here, maintaining the discharge only for a predetermined discharge maintenance time is not limited to the case where the discharge current is suddenly interrupted after the discharge maintenance time has elapsed, but also when the discharge current is gradually attenuated and does not flow after the discharge maintenance time has elapsed. Including.

  However, even if a battery is selected, if the discharge is not performed unless a discharge is instructed, this discharge is limited to a relatively short time even if the discharge sustaining circuit maintains the discharge permanently. There is no need to instruct to stop discharging unless it is necessary to perform the discharge, and discharge that has been maintained since the previous selection can be stopped by not instructing discharge at the next selection of the battery.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS. 1 to 2, the same reference numerals are given to the constituent members having the same functions as those of the conventional example shown in FIG.

As in the conventional example shown in FIG. 3, the present embodiment is a battery management device that manages an assembled battery in which a number of batteries 1 made of nonaqueous electrolyte secondary batteries are connected in series by a single microcomputer 4. The microcomputer 4 selects each battery 1 to detect a voltage, and discharges the battery 1 having an abnormal voltage so that the battery 1 of the assembled battery is balanced. is there. However, in the battery management device of this embodiment, as shown in FIG. 1, a discharge circuit 5 is connected to each battery 1. Therefore, the discharge current of each battery 1 flows through the discharge circuit 5 on the battery 1 side rather than the pulse transformer 3 instead of the microcomputer 4 side via the pulse transformer 3. Accordingly, the FET ₄ for flowing a discharge current shown in the conventional example of FIG. 3 is not used. Since each battery 1 is always discharged through the discharge circuit 5 at the time of selection, the microcomputer 4 does not need to output a discharge instruction signal. digital output terminal D _D not also provided.

The discharge circuit 5, when the discharge transistor Q _D is turned ON, a circuit the discharge current now flows through the discharge resistor R _D and the discharge transistor Q _D from the battery 1. Then, the discharge transistor _{Q D} is turned ON by the FET ₁ of the selected sustain circuit 2 the cell 1 is selected and turned ON. Further, this discharge transistor Q _D, since the integrating capacitor C _I is connected, also returns to OFF after becoming not output a trigger signal after a lapse of FET ₁ is selected maintenance time, not be immediately turned OFF Then, it gradually returns to OFF over a predetermined discharge maintenance time.

As a result, when the microcomputer 4 outputs any battery selection signal by setting any _{one of the} digital output terminals D _{1 to} D _n to the H level, when the corresponding one battery 1 is selected, the pulse transformer of the battery 1 is selected. 3 secondary side FET ₂ is turned ON. Next, when the FET ₃ is turned on by outputting a trigger signal with the digital output terminal _DT bar at the L level, a voltage is induced in the primary winding of the pulse transformer 3 and the FET _{1 of the} selection maintaining circuit 2 is turned on. Become. Further, by the FET ₁ is ON, the discharge transistor _{Q D} of the discharge circuit 5 is also turned ON, the discharge current from the battery 1 starts to flow in the discharge circuit 5. If the ON state of the FET ₁ is maintained for a predetermined selection maintaining time even after the trigger signal is not output due to the single oscillation operation of the selection maintaining circuit 2, the voltage of the battery 1 causes the pulse transformer 3 to pass through during this period. while being transmitted to the analog input terminal a _iN of the microcomputer 4 through even discharge circuit 5, the discharge transistor Q _D is kept in the oN state, the discharge is continued. In this embodiment, since the actual battery 1 is selected by a combination of the battery selection signal and the trigger signal, the period during which the original battery 1 is selected is the period during which the FET ₁ is ON. Become.

Here, if the discharge stops as the selection maintaining time elapses, the same discharge as in the conventional example is performed. However, in the present embodiment, even FET ₁ elapses selected maintaining time is returned to OFF, ON state to the active state of the integrating capacitor C by _I for a predetermined sustaining time discharge transistor Q _D of the discharge circuit 5 is maintained Therefore, the discharge current flows while being attenuated. Therefore, even if the selection of the previous battery 1 is completed and the next battery 1 is selected, the discharge current from the previous battery 1 continues to flow to the discharge circuit 5 until the discharge maintenance time elapses. As described above, a larger amount of discharge current can be discharged than when the discharge is performed only during the selection maintaining time during the selection period. Moreover, the discharge circuit 5 is not shared on the microcomputer 4 side as in the conventional example, but is provided for each battery 1, so that the next battery 1 is selected during the discharge of the previous battery 1. Thus, the voltage can be detected. Furthermore, it is possible to simultaneously select a plurality of batteries 1 and discharge these batteries 1 simultaneously.

  With the above configuration, the battery management device of the present embodiment detects the voltages of these batteries 1 by selective scanning processing that sequentially selects each battery 1, and determines that the voltage of any one of the batteries 1 is abnormally high In this case, the selective scanning process is temporarily interrupted, and only the battery 1 is repeatedly selected, so that the discharge current can continuously flow through the discharge circuit 5. In particular, when there are a plurality of batteries 1 whose voltages are determined to be abnormally high, if only these batteries 1 are selected simultaneously or sequentially, the discharge currents of the plurality of batteries 1 are continuously supplied to the discharge circuits 5 simultaneously. Therefore, the discharge can be completed in a short time and the selective scanning process can be restarted at an early stage. In addition, during the cycle of the selective scanning process, by appropriately selecting the battery 1 that is originally selected only once, the battery 1 is discharged in a large amount of time during the selective scanning process. (The duty ratio of the discharge increases), thereby eliminating the need to interrupt the selective scanning process.

  In addition, in the battery management apparatus of this embodiment, since the discharge is performed only by selecting the battery 1 and sending a trigger signal, the selective scanning process for detecting the voltage of each battery 1 is performed. Each time these batteries 1 are selected, they are discharged for a time slightly longer than the discharge maintaining time. However, if the number of batteries 1 is sufficiently large, the selective scanning process can be repeated by making the discharge maintaining time sufficiently shorter than the scanning period for making a full selection of all the batteries 1. Thus, the duty ratio during the period during which discharge is performed can be reduced, and waste of electric power due to this can be hardly generated. In addition, when repeatedly selecting only a plurality of batteries 1 whose voltages are abnormally high in order, by making the discharge maintenance time longer than a period for making a round of selection of the plurality of batteries 1, It becomes possible to discharge efficiently.

  As described above, according to the battery management apparatus of the present embodiment, the discharge circuit 5 can continue to flow the discharge current even after the selection of the battery 1 is completed, so the discharge of the battery 1 for balancing the assembled battery Can be done quickly.

In the present embodiment having the above configuration, the FET _{2 that} is turned on by the battery selection signal from the microcomputer 4, the FET _{3 that} is turned on by the trigger signal, the pulse transformer 3, and the selection maintaining circuit 2 including the pulse transformer 3. The blocking oscillation circuit becomes a battery selection circuit for selecting the battery 1, and the pulse transformer 3 for transmitting the voltage of the battery 1 selected by the battery selection circuit to the analog input terminal _AIN of the microcomputer 4 detects the battery voltage. It becomes a circuit. Moreover, the discharge circuit 5 with the exception of the integrating capacitor C _I becomes a battery discharge circuit, circuit connected to the integrating capacitor C _I to the discharge circuit 5 is sustaining circuit.

In the above embodiment, the case where one pulse transformer 3 is provided for each battery 1 is shown. However, as shown in FIG. 2, the polarity of each pulse transformer 3 is reversed between adjacent batteries 1 and 1. By using it, one pulse transformer 3 can be shared by the two batteries 1 and 1, and the number of these pulse transformers 3 can be halved. However, in this case, an analog input terminal _AIN1 for inputting one voltage of each of the two batteries 1, 1 sharing the pulse transformer 3, and an analog input terminal for inputting the other voltage A _IN2 and the microcomputer 4 must be provided separately. The trigger signal is also output separately from the digital output terminal D _T1 bar and the digital output terminal D _T2 bar, and the FET ₃₁ and the FET ₃₂ are used to connect one end and the other end of the secondary winding of the pulse transformer 3 to the power source V _DD. Must be connected to. Moreover, the two batteries 1 and 1 connected to the same pulse transformer 3 cannot be selected at the same time because the trigger signal has a reverse polarity. Therefore, when the batteries 1 and 1 connected to the same pulse transformer 3 are discharged together as described above, they are alternately selected, but the other one of the discharges of the batteries 1 is selected. It can be performed continuously continuously.

  Further, in the above embodiment, the selection state of the battery 1 is maintained for a predetermined selection maintaining time determined by the time constant by causing the blocking oscillation circuit including the selection maintaining circuit 2 and the pulse transformer 3 to oscillate once by the trigger signal. For example, the battery 1 may be in a selected state only during a period from when a trigger signal for selection setting is sent using a memory circuit such as a flip-flop circuit to when a trigger signal for deselection is sent. Furthermore, in the above embodiment, since the battery selection circuit and the battery voltage detection circuit share the same pulse transformer 3, it is necessary to maintain the selection state of the battery 1 using such a trigger signal. For example, when the battery selection circuit is configured by providing a pulse transformer different from the pulse transformer 3 of the battery voltage detection circuit, the original selection of the battery 1 is possible only by the battery selection signal, and it is necessary to use a trigger signal. Disappear.

  Further, in the above embodiment, the case where the discharge is performed even when the battery 1 is selected only for the detection of the voltage is shown. However, even if the battery 1 is selected, the discharge is performed unless the discharge is instructed. It can also be prevented. In this case, the selective scanning process for selecting each battery 1 in order is repeatedly performed to detect the voltage as needed, and the discharge can be performed only when a specific battery 1 is selected. That is, in this case, the predetermined discharge maintaining time can be made longer than the scanning period for completing the selection of all the batteries 1 or the discharge can be maintained permanently. The discharge can be continuously maintained even while the battery 1 is selected. However, when the discharge is maintained permanently, when the voltage of the battery 1 returns to normal, an instruction to stop the discharge is performed, or the discharge is not instructed at the next selection, It is necessary to stop this discharge. By the way, if the battery 1 is discharged during the selective scanning process in this way, the voltage of the battery 1 cannot be detected. For example, the battery 1 is repeated every time the selective scanning process is repeated several times. If the normal voltage is detected by temporarily interrupting the discharge, it can be determined that the voltage has returned to normal. Further, if the selection period is sufficiently long, the voltage can be detected in the first half and the discharge can be instructed in the second half. The selection period of the battery 1 can be lengthened or continuously selected. It is also possible to instruct discharge in the second half of this selection period or the second selection period. However, since it is impossible to instruct such discharge through the pulse transformer 3 of the battery voltage detection circuit, it is necessary to instruct the discharge from the microcomputer 4 to the discharge circuit 5 through another pulse transformer, for example. There is.

  Moreover, although the case where the pulse transformer 3 was used was shown in the said embodiment, if there is no trouble in reliability etc., isolation can also be performed using a photocoupler etc. However, although the pulse transformer 3 can perform bidirectional transmission, the photocoupler can perform only one-way transmission. Therefore, the battery selection circuit and the battery voltage detection circuit cannot share the same photocoupler. However, if isolation is unnecessary, the battery selection circuit, the battery voltage detection circuit, the battery discharge circuit, etc. can be obtained by using only a switch circuit such as an FET or a resistor without using such a pulse transformer 3 or a photocoupler. Can also be configured.

In the above embodiment, the microcomputer 4 has an analog input interface with a built-in A / D conversion circuit. However, input is performed from a digital input terminal via an external A / D conversion circuit. It can also be done. Further, in the above embodiment, there has been shown a case _where there are n batteries 1 and the microcomputer 4 has n digital output terminals D _{1 to} D _n for selecting these batteries 1. When 4 does not select a plurality of batteries 1 at the same time, n digital output terminals D _{1 to} D _n and each FET ₂ are connected via a decoder (demultiplexer) to obtain 2 Selection control of the ⁿ batteries 1 can be performed. In this case, the microcomputer 4 selects only one battery 1 corresponding to the binary number by outputting the binary number from the digital output terminals D _{1 to} D _n .

  Moreover, although the said embodiment demonstrated the battery management apparatus which manages the assembled battery of a nonaqueous electrolyte secondary battery, the kind of battery used for an assembled battery is arbitrary. Further, the assembled battery is not limited to all batteries connected in series, but may be a battery connected in parallel or a combination of series connection and parallel connection. Furthermore, each battery of this assembled battery is not limited to a single battery, and may be a battery in which a plurality of single batteries are connected internally.

1 is a circuit diagram illustrating a configuration of a battery management apparatus according to an embodiment of the present invention. FIG. 10 is a circuit diagram illustrating another configuration of a battery management apparatus that shares an embodiment of the present invention and shares a pulse transformer. It is a circuit diagram which shows a prior art example and shows the structure of a battery management apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Selection maintenance circuit 3 Pulse transformer 4 Microcomputer 5 Discharge circuit

Claims (2)

In a battery management device that manages an assembled battery in which a plurality of batteries are connected,
A battery selection circuit for selecting each battery based on a selection signal from the microcomputer, and a battery voltage detection circuit for inputting the voltage of each battery selected by the battery selection circuit to the microcomputer;
A battery comprising: a battery discharge circuit for discharging the battery selected by the battery selection circuit for each battery; and a discharge maintaining circuit for discharging the battery by the battery discharge circuit after the selection of the battery is completed. Management device.   2. The battery management apparatus according to claim 1, wherein the discharge maintaining circuit maintains the discharge of the battery only for a predetermined discharge maintaining time after the selection of the battery is completed.

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