JP2010115078A - Method of controlling battery discharge and discharge control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling battery discharge capable of preventing over discharge of batteries. <P>SOLUTION: The method includes steps of: calculating load rates, based on discharge currents from DC power supplies 1 composed by connecting the same kind of batteries in parallel; detecting battery voltages of the DC power supplies; clocking the elapsed time after discharging the DC power supplies is started; and using the calculated load rates, the detected battery voltages, and the clocked elapsed time to refer to a discharge current vs. discharge termination voltage characteristic table 21, where discharge currents of single discharge characteristics of the batteries are correlated with discharge termination voltages, a load rate vs. discharge current characteristic table 22, where the load rates when the number of parallel batteries is set to 1 are correlated with the discharge currents, and a load rate vs. discharge allowable time characteristic table 23, where the load rate for each number of parallel batteries is correlated with discharge allowable time, to predict the number of parallel batteries and to set the discharge termination voltage of an appropriate value, based on the predicted number of parallel batteries. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery discharge control method and a discharge control apparatus.

  The battery has a discharge end voltage that is the lowest voltage that can be safely discharged. This discharge end voltage varies depending on the magnitude of the discharge current. Generally, the smaller the discharge current, the higher the discharge end voltage. When a DC power source is configured by connecting batteries in parallel, the discharge current increases as I, I / 2,... Therefore, it is necessary to increase the end-of-discharge voltage as the number of parallel batteries increases.

  FIG. 10 is a block diagram showing the configuration of a conventional discharge control device. The discharge control device includes a DC power source 1, a load disconnect switch 2, and a control unit 4a. The DC power supply 1 is configured by connecting batteries in parallel (the number of parallel batteries = n). The output of the DC power source 1 is supplied to the load L via the load disconnection switch 2.

  The load separation switch 2 opens and closes in response to a control signal from the control unit 4a, and controls the supply of the output of the DC power source 1 to the load L. The control unit 4a detects the voltage of the DC power source 1 and outputs a control signal to the load disconnect switch 2 when the detected voltage reaches the discharge end voltage to disconnect the load L. Thereby, overdischarge of the battery is prevented.

  FIG. 11 is a block diagram showing the configuration of another conventional discharge control device. This discharge control device is further provided with a current detector 3 and a battery parallel number setting switch 5 in addition to the configuration of the discharge control device shown in FIG. The current detector 3 detects the magnitude of the discharge current (load current) of the DC power source 1 and sends the detected current value to the control unit 4b. The battery parallel number setting switch 5 sets the battery parallel number of the DC power supply 1 and outputs the set battery parallel number to the control unit 4b.

  The control unit 4b calculates the discharge current flowing through one battery by dividing the current value from the current detector 3 by the battery parallel number from the battery parallel number setting switch 5. The control unit 4b detects the voltage of the DC power source 1, and outputs a control signal to the load disconnection switch 2 to disconnect the load L when the detected voltage becomes equal to or lower than the discharge end voltage corresponding to the calculated discharge current. . Thereby, overdischarge of the battery is prevented.

  Patent Document 1 simulates a discharge characteristic curve from input data, displays an alarm when the voltage is assumed to be within the allowable minimum voltage within a specified discharge time, and terminates the discharge determined from the simulated discharge characteristic curve. Disclosed is a storage battery dischargeable time prediction calculation device that displays an alarm a certain time before reaching a voltage and automatically trips the storage battery circuit when the discharge end voltage is reached. This device extracts a storage battery discharge characteristic curve that most closely approximates the storage battery operating state from the output of a comparison device that extracts and converts the DC power supply device data input and conversion characteristics corresponding to the input constant, and an arithmetic unit A device for calculating the time until the allowable minimum voltage is reached and displaying the result on the screen and a command device for tripping the storage battery from the circuit when the discharge end voltage is reached are provided.

Patent Document 2 discloses a method that can easily and almost accurately estimate the discharge characteristics and remaining discharge capacity of a storage battery. In this method, when estimating a discharge characteristic that is a relation between a discharge time and a discharge voltage of a storage battery used for backup of the power supply device during the backup of the power supply device, the discharge voltage of the storage battery is determined at least two times during the backup of the power supply device. Measurement is performed at the time point, and the discharge characteristics are estimated by approximating the curve with a second-order curve passing through the discharge voltage and the discharge end voltage at the two time points. The remaining discharge time of the storage battery is estimated using the discharge characteristic approximated by a curve.
Japanese Patent Laid-Open No. 9-329652 JP 2005-37234 A

However, in the conventional discharge control device, since the control unit 4a cannot recognize the number of parallel batteries, the discharge end voltage becomes a constant value regardless of the number of parallel batteries. If the end-of-discharge voltage is set to the voltage V ₁ when the number of parallel batteries = 1, with a DC power supply having n parallel batteries (n> 1), the battery discharge is the original as shown in FIG. Since it is stopped at a voltage V ₁ lower than the discharge end voltage V _n , overdischarge occurs.

On the other hand, when the end-of-discharge voltage is set to the voltage V _n when the number of parallel-connected batteries is n with a DC power supply with the number of parallel battery = 1, as shown in FIG. 13, the battery is discharged at the original discharge end voltage V _{1. Is} stopped at a higher voltage Vn. In this case, overdischarge can be prevented, but the discharge is completed in a time shorter than the discharge time that can be secured originally, and the battery performance cannot be sufficiently exhibited.

  By setting the battery parallel number setting switch 5 in accordance with the number of parallel batteries constituting the DC power supply 1, the control unit 4b recognizes the number of parallel batteries and thereby discharges at a discharge end voltage suitable for the DC power supply 1. Can be stopped. However, if the setting of the battery parallel number setting switch 5 is mistaken due to an operation mistake, the above-described problem occurs.

  An object of the present invention is to provide a battery discharge control method and a discharge control device that can automatically set an appropriate discharge end voltage to prevent overdischarge of the battery.

  In order to solve the above-described problem, a battery discharge control method according to claim 1 is a method of calculating a load factor based on a discharge current from a DC power source configured by connecting the same type of batteries in parallel; A step of detecting a battery voltage of the power source, a step of measuring an elapsed time from when the discharge of the DC power source is started, the calculated load factor, the detected battery voltage, and the elapsed time measured. The discharge current-discharge end voltage characteristic table in which the discharge current and discharge end voltage of the single discharge characteristic of the battery are associated with each other, and the load factor and discharge current when the number of parallel batteries is 1 are associated with each other. The load factor-discharge current characteristic table and the load factor-dischargeable time characteristic table in which the load factor for each parallel number of the batteries and the dischargeable time are associated with each other are referred to. Predicting the number of parallel Teri, characterized in that it comprises a step of setting the final discharge voltage of an appropriate value based on the number of parallel predicted.

  The battery discharge control device according to claim 2 is a DC power source configured by connecting batteries of the same type in parallel, a load factor calculating unit that calculates a load factor based on a discharge current from the DC power source, and the DC A battery voltage detection unit that detects a battery voltage of the power supply, a timer that measures an elapsed time from when the discharge of the DC power supply is started, and a discharge current and a discharge end voltage of the single discharge characteristic of the battery are associated with each other. Discharge current-end-of-discharge voltage characteristic table, load factor-discharge current characteristic table in which the load factor and discharge current when the parallel number of the batteries is 1 and the load factor for each parallel number of the batteries are dischargeable A storage unit storing a load factor-dischargeable time characteristic table corresponding to time, a load factor calculated by the load factor calculation unit, and a battery detected by the battery voltage detection unit The battery is connected in parallel with reference to the discharge current-discharge end voltage characteristic table, the load factor-discharge current characteristic table, and the load factor-dischargeable time characteristic table using the pressure and the elapsed time measured by the timer. An arithmetic processing unit that predicts the number and sets an appropriate discharge end voltage based on the predicted parallel number.

  According to the present invention, the battery parallel number is predicted from the discharge current and the dischargeable time based on each table, and an appropriate discharge end voltage is set based on the predicted parallel number. Can be prevented. Moreover, the electric power from a battery can be taken out effectively.

  Hereinafter, a battery discharge control method and a discharge control apparatus according to embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the battery discharge control apparatus according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the component same as the structure of the conventional discharge control apparatus shown in FIG. 10, and the description is abbreviate | omitted.

  The discharge control device includes a DC power source 1, a load disconnect switch 2, a current detector 3, and a control unit 4. The DC power supply 1 is configured by connecting batteries in parallel (the number of parallel batteries = n). Each battery is the same type of battery.

  The current detector 3 detects the magnitude of the discharge current (load current) of the DC power supply 1 and outputs the detected current value to the control unit 4. The control unit 4 controls the entire discharge control device. FIG. 2 is a block diagram showing a detailed configuration of the control unit 4. The control unit 4 includes a storage unit 11, a load factor calculation unit 12, a battery voltage detection unit 13, a timer 14, and an arithmetic processing unit 15.

  The storage unit 11 stores a discharge current-discharge end voltage characteristic table 21, a load factor-discharge current characteristic table 22, and a load factor-dischargeable time characteristic table 23. As shown in FIG. 3, the discharge current-discharge end voltage characteristic table 21 defines a relationship in which a discharge current of a single battery discharge characteristic (discharge characteristic of one battery) and a discharge end voltage are associated with each other. Yes. The contents of the discharge current-end-of-discharge voltage characteristic table 21 are determined from the specifications of the single discharge characteristics of the battery.

  In the load factor-discharge current characteristic table 22, as shown in FIG. 4, a relationship in which the load factor and the discharge current are associated with each other when the number of parallel batteries = 1 is defined. The load factor is expressed as (load current / rated load current) × 100%. The content of the load factor-discharge current characteristic table 22 is determined by calculation or by measurement with an actual machine.

  In the load factor-dischargeable time characteristic table 23, as shown in FIG. 5, the load factor when the number of parallel batteries = 1, 2,..., N and the time until discharge ends (dischargeable time) are shown. Corresponding relationships are defined. The contents of the load factor-dischargeable time characteristic table 23 are determined by calculation or by measurement with an actual machine.

  The load factor calculation unit 12 calculates a load factor based on the current value sent from the current detector 3 and the rated load current value stored in advance in itself, and the calculated load factor is calculated by an arithmetic processing unit. 15 is output.

  The battery voltage detection unit 13 constantly detects the battery voltage output from the DC power supply 1 and outputs the detected battery voltage to the arithmetic processing unit 15. The timer 14 starts measuring time when activated by the arithmetic processing unit 15. The elapsed time counted by the timer 14 is read by the arithmetic processing unit 15.

  The arithmetic processing unit 15 sends the discharge current-discharge end voltage characteristic table 21, the load factor-discharge current characteristic table 22 and the load factor-dischargeable time characteristic table 23, and the load factor calculation unit 12 stored in the storage unit 11. Based on the received load factor, the battery voltage sent from the battery voltage detector 13, and the elapsed time sent from the timer 14, a process for predicting the battery parallel number is executed.

  Next, the operation of the discharge control apparatus according to the first embodiment configured as described above will be described with reference to the flowchart shown in FIG. 6 focusing on the parallel number prediction process for predicting the battery parallel number. The battery discharge is assumed to start from a fully charged state.

  First, in the parallel number prediction process, the arithmetic processing unit 15 outputs a start command to the timer 14, and the timer 14 is started and starts measuring time (step S10). Then, the battery parallel number n is set to 1 (step S11). Since the number of parallel batteries is unknown in the initial state, the arithmetic processing unit 15 assumes that the number of parallel batteries is 1.

  Next, the load factor calculation unit 12 calculates a load factor based on the current value sent from the current detector 3 and the rated load current value stored in advance in the self, and sends the load factor to the arithmetic processing unit 15. Output (step S12).

  Next, the discharge current when the number of parallel batteries is n is obtained from the load factor (step S13). That is, the arithmetic processing unit 15 refers to the load factor-discharge current characteristic table 22 stored in the storage unit 11 and obtains a discharge current corresponding to the load factor sent from the load factor calculating unit 12.

  Next, the dischargeable time when the number of parallel batteries is n is obtained from the load factor (step S14). That is, the arithmetic processing unit 15 refers to the load factor-dischargeable time characteristic table 23 stored in the storage unit 11 and corresponds to the battery parallel number n and the load factor sent from the load factor calculating unit 12. Obtain the dischargeable time.

  Next, the arithmetic processing unit 15 refers to the discharge current-discharge end voltage characteristic table 21 stored in the storage unit 11, obtains the discharge end voltage corresponding to the discharge current obtained in step S13, and determines the battery voltage detection unit. It is determined whether the battery voltage sent from 13 is lower than the determined discharge end voltage (step S15).

  In step S15, when the battery voltage is lower than the discharge end voltage, the discharge is stopped (step S16). That is, since the arithmetic processing unit 15 outputs a control signal to the load separation switch 2, the load separation switch 2 is opened, and discharging of the battery is stopped.

  The arithmetic processing unit 15 sets n at that time as the battery parallel number (step S17). Thereby, since the control part 4 can recognize the battery parallel number, it can stop discharge with the discharge final voltage suitable for the DC power supply 1 after that. Then, the parallel number prediction process ends.

  On the other hand, when the battery voltage is not lower than the discharge start voltage in step S15, the arithmetic processing unit 15 reads the elapsed time from the timer 14 and determines whether or not the read elapsed time has exceeded the dischargeable time (step S15). S18). If the elapsed time does not exceed the dischargeable time, the process returns to step S15 and the above-described processing is repeated.

  On the other hand, when the elapsed time exceeds the dischargeable time in step S18, the battery parallel number n is incremented by 1 (step S19). Then, it returns to step S13 and the process mentioned above is repeated.

  Next, a specific example of the battery parallel number prediction realized by the process shown in the flowchart of FIG. 6 will be described.

Initially, since the battery parallel number is unknown, it is assumed that the battery parallel number = 1. When the load factor is x _i (i = 0, 1,..., Max−1, max), the discharge current = I _i with reference to the load factor-discharge current characteristic table 22 shown in FIG. Therefore, the discharge current shown in FIG. 3 - with reference to the discharge end voltage characteristic table 21, the discharge termination voltage = V _i. Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 5, the dischargeable time = t _{1 · i} . If the battery voltage drops to the discharge end voltage V _i by the time t _{1 · i} from the start of discharge, the discharge is stopped. In this case, the predicted number of parallel batteries = 1.

If the elapsed time from the start of discharge exceeds t _{1 · i} , the battery parallel number = 1 and the dischargeable time is exceeded, and it is estimated that the battery parallel number = 2 or more. Assume. At the same time, since the discharge current is ½ of the number of parallel batteries = 1, the discharge current = I _i / 2. Therefore, with reference to the discharge current-discharge end voltage characteristic table 21 shown in FIG. 3, the discharge end voltage when the discharge current = I _i / 2 is obtained (here, the end of discharge when the number of parallel batteries = 2). Voltage = V _i2 ).

Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 5, the dischargeable time = t _2i2 . If the battery voltage falls to the discharge end voltage V _i2 before the time t _2i2 elapses from the start of discharge, the discharge is _stopped . In this case, the predicted number of parallel batteries is 2.

When the elapsed time from the start of discharge exceeds t _2i2 , it is _assumed that the battery parallel number = 2 and the dischargeable time is exceeded, and it is estimated that the battery parallel number = 3 or more. Therefore, it is assumed that the battery parallel number = 3. . At the same time, since the discharge current is 1/3 of the number of parallel batteries = 1, the discharge current = I _i / 3. Therefore, with reference to the discharge current-discharge end voltage characteristic table 21 shown in FIG. 3, the discharge end voltage when discharge current = I _i / 3 is obtained (here, the end of discharge when the number of parallel batteries = 3). Voltage = V _i3 ).

Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 5, the dischargeable time = t _3i3 . When the battery voltage drops to the discharge end voltage V _i by the time t _3i3 elapses from the start of discharge, the discharge is _stopped . In this case, the predicted number of parallel batteries is 3.

Similarly, every time the elapsed time from the start of discharge exceeds t _3i3 , t _4i4 ,..., The predicted number of the battery parallel number is incremented by 1, and the discharge is _stopped by the value obtained by dividing the discharge current by the battery parallel number n. The voltage and the dischargeable time are predicted, and the battery parallel number is predicted based on whether the battery voltage reaches the discharge end voltage within the dischargeable time. And the discharge end voltage according to the estimated number of parallel batteries is set.

  Next, a specific example of battery parallel number prediction will be described using actual numerical values. FIG. 7 is a diagram showing a specific example of a discharge current-discharge end voltage characteristic table 21 representing a discharge current-discharge end voltage characteristic of a battery unit of a manufacturer. In FIG. 7, the discharge current is shown in four sections, but it is not always necessary to have four sections.

  FIG. 8 is a diagram showing a specific example of a load factor-discharge current characteristic table 22 representing a load factor-discharge current characteristic when the number of parallel batteries of a certain device (load) = 1. Further, FIG. 9 is a diagram showing a specific example of the load factor-dischargeable time characteristic table 23 representing the load factor-dischargeable time when the number of parallel batteries = 1, 2, 3, 4.

  Here, it is assumed that the load factor is 100%. Initially, since the number of parallel batteries is unknown, it is assumed that the number of parallel batteries = 1. Since the load factor is 100%, the discharge current is 21.6 A with reference to the load factor-discharge current characteristic table 22 shown in FIG. For this reason, with reference to the discharge current-discharge end voltage characteristic table 21 shown in FIG. 7, the discharge end voltage = 10.0V. Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 9, the dischargeable time = 5 minutes.

  If the battery voltage drops to a discharge end voltage of 10.0 V before 5 minutes have elapsed from the start of discharge, the discharge is stopped. In this case, the predicted number of parallel batteries = 1.

  When the elapsed time from the start of discharge exceeds 5 minutes, it is assumed that the battery parallel number = 1 and the dischargeable time is exceeded and the battery parallel number = 2 or more, so it is assumed that the battery parallel number = 2. . At the same time, since the discharge current is ½ of the number of parallel batteries = 1, the discharge current = 10.8 A. For this reason, referring to the discharge current-discharge end voltage characteristic table 21 shown in FIG. 7, when the discharge end voltage at the time of discharge current = 10.8 A is obtained, the discharge end voltage = 10.32V. Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 9, the dischargeable time = 10 minutes.

  If the battery voltage drops to a discharge end voltage of 10.32 V by 10 minutes after the start of discharge, the discharge is stopped. In this case, the predicted number of parallel batteries = 2.

  If the elapsed time from the start of discharge exceeds 10 minutes, it is assumed that the battery parallel number = 2 exceeds the time that can be discharged, and the battery parallel number = 3 or more, so it is assumed that the battery parallel number = 3. To do. At the same time, since the discharge current is 1/3 of the case where the number of parallel batteries = 1, the discharge current = 21.6 / 3 = 7.2A. For this reason, referring to the discharge current-discharge end voltage characteristic table 21 shown in FIG. 7, when the discharge end voltage when the discharge current = 7.2 A is obtained, the discharge end voltage = 10.32V. Further, referring to the load factor-dischargeable time characteristic table 23 shown in FIG. 9, dischargeable time = 16 minutes.

  The discharge is stopped when the battery voltage drops to 10.32 V until the end of 16 minutes from the start of the discharge. In this case, the predicted number of parallel batteries = 3. Hereinafter, similarly, the battery parallel number is predicted, and the discharge end voltage is set according to the predicted battery parallel number.

It is a block diagram which shows the structure of the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a block diagram which shows the detailed structure of the control part of the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the discharge current-discharge end voltage characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the load factor-discharge current characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the load factor-dischargeable time characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a flowchart which shows operation | movement of the discharge control apparatus which concerns on Example 1 of this invention centering on the parallel number prediction process which estimates a battery parallel number. It is a figure which shows the specific example of the discharge current-discharge end voltage characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the specific example of the load factor-discharge current characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the specific example of the load factor-dischargeable time characteristic table used with the discharge control apparatus of the battery which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the conventional discharge control apparatus. It is a block diagram which shows the structure of the other conventional discharge control apparatus. It is a figure for demonstrating operation | movement of the conventional discharge control apparatus. It is a figure for demonstrating operation | movement of the conventional discharge control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Load isolation | separation switch 3 Current detector 4 Control part 11 Memory | storage part 12 Load factor calculation part 13 Battery voltage detection part 14 Timer 15 Arithmetic processing part 21 Discharge current-discharge end voltage characteristic table 22 Load ratio-discharge current characteristic table 23 Load factor-dischargeable time characteristics table L Load

Claims (2)

Calculating a load factor based on a discharge current from a DC power source configured by connecting the same type of batteries in parallel;
Detecting a battery voltage of the DC power supply;
Measuring the elapsed time since the discharge of the DC power supply was started;
A discharge current-discharge end voltage characteristic table in which the discharge current of the single discharge characteristic of the battery and the discharge end voltage are associated with each other using the calculated load factor, the detected battery voltage, and the elapsed time measured. The load factor corresponding to the load factor and the discharge current when the parallel number of the batteries is 1, the discharge factor characteristic table and the load factor corresponding to the load factor and the dischargeable time for each parallel number of the battery Predicting the parallel number of the batteries with reference to a dischargeable time characteristic table, and setting an appropriate value of the discharge end voltage based on the predicted parallel number;
A battery discharge control method comprising: A DC power source configured by connecting the same type of batteries in parallel;
A load factor calculation unit for calculating a load factor based on a discharge current from the DC power supply;
A battery voltage detector for detecting a battery voltage of the DC power supply;
A timer for measuring the elapsed time from when the discharge of the DC power supply is started;
Discharge current corresponding to discharge current and discharge end voltage of the single discharge characteristics of the battery-discharge end voltage characteristic table, load ratio corresponding to load ratio and discharge current when the number of parallel batteries is 1- A storage unit storing a discharge current characteristic table and a load factor-dischargeable time characteristic table in which a load factor and a dischargeable time for each parallel number of the batteries are associated;
Using the load factor calculated by the load factor calculator, the battery voltage detected by the battery voltage detector and the elapsed time measured by the timer, the discharge current-end-of-discharge voltage characteristic table, the load factor- An arithmetic processing unit that predicts the parallel number of the batteries with reference to a discharge current characteristic table and the load factor-dischargeable time characteristic table, and sets an appropriate value of the discharge end voltage based on the predicted parallel number;
A battery discharge control device comprising:

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