JP2006090848A - Battery condition detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery condition detector for accurately grasping the condition of a battery at all times. <P>SOLUTION: A CPU 23a uses a temperature sensor 27 to causes a battery 13 to discharge electricity into a high-rate discharge circuit 25 correspondently to a change in battery temperature. Further, the CPU 23a measures a terminal voltage and discharge current of the battery 13 in process of its discharge to detect the condition of the battery based on the measured terminal voltage and discharge current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery state detection device, and more particularly to a battery state detection device that detects a battery state.

  For example, taking a battery mounted on a vehicle as an example, an electric vehicle using a motor as the only propulsion drive source corresponds to gasoline in a vehicle using a general engine as the propulsion drive source. For this reason, it is very important to detect the state of the battery in order to ensure normal traveling of the vehicle.

  By the way, in an in-vehicle battery, discharge is performed through a starter motor when the engine is started. At this time, the current increases in a short time to a very large maximum current value, which is generally called an inrush current, compared to the steady current value of the starter motor. However, a discharge current that decreases in a short time from the maximum current to the steady current value flows. In general, such a discharge is called a high rate discharge.

  Therefore, if the discharge current of the battery and the corresponding terminal voltage of the battery are measured during high rate discharge, the change of the terminal voltage with respect to the change of the discharge current in a wide range from 0 to the maximum current value can be measured. The state of the battery can be detected based on the discharge current and terminal voltage measured during the high rate discharge.

  Specifically, for example, the internal resistance of the battery, the dischargeable capacity, and the like can be detected. The internal resistance described above increases with the progress of battery deterioration, and thus the battery deterioration can be grasped. On the other hand, the dischargeable capacity is obtained by subtracting the capacity that cannot be discharged due to the voltage drop generated by the internal resistance of the battery from the charge capacity of the battery, so that it can be determined whether or not the load can be driven reliably. it can. That is, the battery state can be detected by obtaining the internal resistance and the dischargeable capacity.

  In addition, as shown in Non-Patent Document 1, a method for detecting the state of a battery, such as one that measures the conductance of a battery by pulse discharge and measures whether or not the battery has deteriorated by measuring the conductance, is a conventional method. Many things are considered.

  By the way, the charge capacity and the internal resistance of the battery are affected by the ambient temperature. This is because the battery temperature changes under the influence of the ambient temperature, and the state of the battery changes according to the change in the battery temperature. In particular, in a vehicle, the ambient temperature of the battery may change abruptly, such as when the engine is started, and the state of the battery may also change in response to this sudden change in ambient temperature.

However, conventionally, for example, only a device that performs temperature correction when detecting a battery state has been proposed (for example, Patent Documents 1 and 2). The invention described in Patent Document 1 can perform accurate detection considering the battery temperature at the time of detecting the battery state. However, when a sudden battery temperature change occurs after the detection, there is a problem that an accurate battery state cannot be grasped until the next detection is performed.
JP-A-9-33621 JP 2003-45503 A "Development of test vehicle battery" FGUARDTM "with built-in tester function" (FB Technical News No.59)

  Accordingly, the present invention focuses on the above-described problems, and an object thereof is to provide a battery state detection device that can always accurately grasp the state of the battery.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a battery state detection device including a state detection unit for detecting a battery state, a temperature detection unit for detecting the temperature of the battery, and a battery temperature. The battery state detection apparatus includes a control unit that causes the state detection unit to detect a battery state in response to a change in the battery level.

  According to the first aspect of the present invention, the state detecting means detects the battery state. The temperature detecting means measures the temperature of the battery. The control means causes the state detection means to detect the battery state according to the change in the battery temperature. Therefore, the battery state can be detected when the battery temperature changes and the battery state changes.

  Invention of Claim 2 is a battery state detection apparatus of Claim 1, Comprising: The discharge circuit which discharges the said battery at arbitrary time is further provided, The said state detection means is the terminal voltage of the said battery during discharge, and The discharge current is measured, and the battery state is detected based on the measured terminal voltage and discharge current, and the control means causes the discharge circuit to discharge from the battery according to a change in the battery temperature, and the state The present invention resides in a battery state detection device characterized by causing a detection means to detect a battery state.

  According to the invention described in claim 2, the discharge circuit discharges the battery at an arbitrary time. The state detection means measures the terminal voltage and discharge current of the battery being discharged, and detects the battery state based on the measured terminal voltage and discharge current. The control means causes the discharge circuit to discharge the battery according to the change in the battery temperature, and causes the state detection means to detect the battery state. Therefore, when the battery temperature changes and the battery state changes, the discharge circuit discharges the battery, and the battery state can be detected based on the terminal voltage and discharge current measured during the discharge.

  The invention according to claim 3 is the battery state detection device according to claim 2, wherein the discharge circuit discharges the battery at a high rate at an arbitrary time point.

  In the invention according to claim 3, the discharge circuit discharges the battery at an arbitrary time. Therefore, the battery state can be detected based on the change in the terminal voltage with respect to the change in the discharge current in a wide range.

  A fourth aspect of the present invention is the battery state detection device according to any one of the first to third aspects, wherein the control means is configured such that a difference between the battery temperature at the previous state detection and the current battery temperature is a predetermined value. When it becomes above, it exists in the battery state detection apparatus characterized by making the said state detection means detect a battery state, assuming that the said battery temperature has changed.

  According to the fourth aspect of the present invention, the control means determines that the battery temperature has changed when the difference between the battery temperature at the previous state detection and the current battery temperature is equal to or greater than a predetermined value. To detect battery status. Therefore, when the battery temperature changes by a predetermined value or more from the previous state detection and the battery state changes, the discharge circuit discharges the battery and the battery voltage is measured based on the terminal voltage and discharge current measured during the discharge. The state can be detected.

  As described above, according to the first aspect of the present invention, since the battery state can be detected when the battery temperature changes and the battery state changes, the battery state can be always accurately grasped. It is possible to obtain a battery state detection device capable of

  According to the invention described in claim 2, when the battery temperature changes and the battery state changes, the battery is discharged to the discharge circuit, and the battery state is determined based on the terminal voltage and the discharge current measured during the discharge. Therefore, it is possible to obtain a battery state detection device that can always accurately grasp the state of the battery.

  According to the third aspect of the invention, since the battery state can be detected based on the change in the terminal voltage with respect to the change in the discharge current in a wide range, the battery state detection that can accurately grasp the state of the battery. A device can be obtained.

  According to the fourth aspect of the present invention, when the battery temperature changes by a predetermined value or more from the previous state detection and the battery state changes, the discharge circuit discharges the battery and the terminal voltage measured during the discharge Since the battery state can be detected on the basis of the discharge current, a battery state detection device that can always accurately grasp the state of the battery can be obtained.

  Hereinafter, the battery state detection apparatus of this invention is demonstrated based on drawing. FIG. 1 is a block diagram showing an embodiment of a battery state detection device of the present invention. The apparatus of this embodiment indicated by reference numeral 1 in the figure is mounted on a vehicle having a motor generator 5 in addition to the engine 3.

  The vehicle travels by transmitting the output of the engine 3 from the drive shaft 7 to the wheels 11 via the differential case 9. In addition, this vehicle is configured to cause the motor generator 5 to function as a generator (generator) during deceleration or braking and to convert the kinetic energy into electric energy to charge the battery 13. The battery 13 here refers to a secondary battery such as a lead acid battery, a nickel metal hydride battery, or a lithium ion battery.

  Further, the battery state detection device is provided with a high rate discharge circuit 25 (discharge circuit) connected in parallel to the motor generator 5. The high-rate discharge circuit 25 includes a load circuit composed of, for example, a capacitor and a resistor, and a switch for connecting the load circuit to the battery 13. In the above-described high rate discharge circuit 25, when the switch is turned on and the load circuit is connected to the battery 13, the discharge current of the battery 12 increases in a short time to a value corresponding to the load circuit, and then decreases in a short time. . Therefore, it can be regarded as a large inrush current until the reduction of the discharge current is completed in a short time, and the discharge by the high rate discharge circuit 25 can be regarded as a high rate discharge.

  Here, the high rate discharge is generally called an inrush current, and increases to a very large current in a short time compared to the steady current value (0 A in the case of the high rate discharge circuit 25). This is a discharge in which a discharge current that decreases to a value in a short time flows. The above short time is a time that allows the growth of polarization to be approximated with a high correlation with the discharge current, and the large current is a voltage growth accuracy that takes into account voltage detection accuracy and current detection accuracy. It is a current that can be measured. Specifically, in the case of a lead battery, a short time can be, for example, 400 msec or less, and a large maximum current can be, for example, 3 C or more.

  Returning to the description of the configuration, the device 1 of the present embodiment is also connected in series to the battery 13, a current sensor 15 that detects the discharge current of the battery 13, and a resistance of about 1 M ohm connected in parallel to the battery 13. The voltage sensor 17 has a value and detects the terminal voltage of the battery 13, and the temperature sensor 27 (= temperature detection means) that detects the battery temperature of the battery 13.

  In addition, the apparatus 1 of the present embodiment includes a microcomputer (hereinafter, referred to as the microcomputer) in which the outputs of the current sensor 15 and the voltage sensor 17 described above are captured after A / D conversion in the interface circuit (hereinafter abbreviated as “I / F”) 21. Abbreviated as “microcomputer”) 23.

  The microcomputer 23 includes a CPU 23a, a RAM 23b, and a ROM 23c, and the CPU 23a is connected to the I / F 21 in addition to the RAM 23b and the ROM 23c. In addition, a starter switch, an ignition switch, an accessory switch, a switch for an electrical component (load) other than the motor generator 5 described above are further connected.

  The RAM 23b has a data area for storing various data and a work area used for various processing operations, and the ROM 23c stores a control program for causing the CPU 23a to perform various processing operations.

  Note that the current values and voltage values that are the outputs of the current sensor 15 and the voltage sensor 17 described above are sampled at high speed in a short cycle, and are taken into the CPU 23a of the microcomputer 23 via the I / F 21. The voltage value is used for various processes.

  The operation of the battery state detection device having the above-described configuration will be described below with reference to the flowchart of FIG. 2 showing the processing procedure of the CPU 23a. The CPU 23a intermittently samples the output of the temperature sensor 27 and determines whether or not the battery temperature has changed (step S1). If there is no change in the battery temperature (N in Step S1), the CPU 23a immediately returns to Step S1.

  On the other hand, for example, when the difference between the battery temperature when the previous battery state was detected and the current battery temperature is greater than or equal to a predetermined value, the CPU 23a determines that the battery temperature has changed (in step S1). Y) The load circuit in the high rate discharge circuit 25 is connected to the battery 13 to cause the battery 13 to perform high rate discharge (step S2).

  Next, the CPU 23a samples the outputs of the current sensor 15 and the voltage sensor 17 at a high speed, and measures the terminal voltage and the discharge current during high rate discharge (step S3). Thereafter, the CPU 23a detects, for example, an internal resistance and a dischargeable capacity based on the measured terminal voltage and discharge current, detects the battery state (step S4), and returns to step S1 again. As is clear from the above operation, the CPU 23a constitutes a control means and a state detection means in the claims.

  According to the battery state detection device described above, when the battery temperature changes by a predetermined value or more from the previous state detection and the state of the battery changes, the high-rate discharge circuit 27 discharges the battery 13 and during the discharge. Since the battery state can be detected based on the measured terminal voltage and discharge current, the state of the battery can always be accurately grasped.

  Note that, according to the above-described embodiment, the battery state is detected only at the timing when the temperature changes. However, it is also possible to detect the battery state at regular time intervals and detect the battery state even if the fixed time has not elapsed when there is a temperature change.

  The temperature sensor 27 that detects the battery temperature described above may be a sensor that directly detects the battery temperature or a sensor that indirectly detects the ambient temperature in the vicinity of the battery 13 as the battery temperature.

It is a block diagram which shows one Embodiment of the battery state detection apparatus of this invention. It is a flowchart which shows the process sequence of CPU23a which comprises the battery state detection apparatus of FIG.

Explanation of symbols

23a CPU (state detection means, control means)
25 High rate discharge circuit (discharge circuit)
27 Temperature sensor (temperature detection means)

Claims (4)

A battery state detection device comprising state detection means for detecting a battery state,
Temperature detecting means for detecting the temperature of the battery;
A battery state detection apparatus comprising: control means for causing the state detection means to detect a battery state in response to a change in battery temperature. The battery state detection device according to claim 1,
A discharge circuit for discharging the battery at an arbitrary time;
The state detection means measures the terminal voltage and discharge current of the battery being discharged, and detects the battery state based on the measured terminal voltage and discharge current,
The control means causes the discharge circuit to discharge from the battery in accordance with a change in the battery temperature, and causes the state detection means to detect a battery state. The battery state detection device according to claim 2,
The battery state detection device, wherein the discharge circuit discharges the battery at a high rate at an arbitrary time. The battery state detection device according to any one of claims 1 to 3,
When the difference between the battery temperature at the time of the previous state detection and the current battery temperature is equal to or greater than a predetermined value, the control unit causes the state detection unit to detect the battery state, assuming that the battery temperature has changed. A battery state detecting device.

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