JPH06207973A - Battery remaining capacity measuring device - Google Patents

Abstract

PURPOSE:To compensate for temperature accordingly to the characteristics of individual current sensors and improve measuring accuracy of remaining capacity by catching the outputs of current sensors at the time when driving power is given, as actual offset values prior to running or charging and correcting the offset so that the sensor outputs at the moment become 0. CONSTITUTION:At every start of running, a breaker switch 8 is closed under the control of a CPU 2. Prior to connecting a main battery 1 to the driver 9 of a motor M, the driving power is given to a current sensor 13 and the offset is corrected every time so that the sensor 13 output becomes 0 when the driving power is given. Prior to every charging of the battery 1 with a charger 11 under the control of the CPU 2, driving power is given to the current sensor 12 and the offset is corrected every time so that the sensor 12 output becomes 0 when the driving power is given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery remaining capacity measuring device for measuring the remaining capacity of a battery.

[0002]

2. Description of the Related Art Generally, in an electric vehicle, the remaining capacity of a battery, which is a power source for the power source, is constantly measured so that the remaining driving capacity or the remaining driving time of the vehicle can be grasped. It has to be displayed.

In a conventional battery remaining capacity measuring apparatus, a known battery discharge characteristic at room temperature, which indicates the remaining capacity at that time with respect to the open circuit voltage of the battery, is converted into data in advance and stored in a memory, and the actual load is measured. The discharge current of the battery at that time and the terminal voltage of the battery at that time are respectively detected to obtain the open circuit voltage (internal electromotive force) of the battery by a predetermined arithmetic processing, and the value is calculated from the memory according to the value of the obtained open circuit voltage. The remaining capacity of the corresponding battery is read out (see Japanese Patent Laid-Open No. 3-180784).

In this case, since the open circuit voltage of the battery changes depending on the temperature, when the arithmetic processing unit A / D-converts the detected battery discharge current and the terminal voltage and reads them, the resistance depends on the temperature. Temperature compensation is performed by appropriately changing the comparison reference voltage supplied to the A / D converter by a circuit using an element whose value changes, and calculating the open circuit voltage from each A / D converted digital value at that time. It is carried out.

However, in such a structure, the entire structure becomes complicated, and the remaining capacity is obtained at a rate according to the preset discharge characteristics of the battery. The remaining capacity cannot be accurately measured.

Conventionally, the charge and discharge currents of a battery are detected by a current sensor, and the remaining capacity of the battery is obtained by calculation processing by integrating the charge amount and the discharge amount. In that case, In order to measure the remaining capacity of the battery with high accuracy, there is a large proportion that depends on the detection accuracy of the current sensor.

When the charge and discharge currents of a battery are detected by a current sensor using a Hall element, the current sensor is easily affected by fluctuations in ambient temperature, and temperature fluctuations cause sensor errors, especially when batteries are installed in automobiles. In this case, the change in the traveling environment is remarkable, and the temperature variation is wide, for example, about -20 ° C to + 60 ° C, and it is necessary to perform temperature compensation of the sensor output.

Therefore, conventionally, the offset values at various temperatures are previously set to one ratio and stored in the memory, and the offset value according to the measured temperature at the time of current detection is read from the memory and the current at that time is read. By performing offset correction of the detected value, temperature compensation of the current sensor output is performed.

[0009]

The problem to be solved is to detect the charging / discharging current of the battery by the current sensor and to integrate the charging amount and the discharging amount of the battery so that the remaining capacity of the battery is calculated. When asking for
When the offset value according to the temperature at the time of current detection is read from the memory and the offset correction of the current detection value at that time is performed, the content of the offset correction is only one, and it depends on the characteristics of each current sensor. In addition, it is impossible to perform proper temperature compensation, and the remaining capacity measurement accuracy deteriorates.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a battery remaining capacity measuring device which detects a battery discharge current by a current sensor and integrates the discharged amount to obtain the battery remaining capacity. When starting a device to be used as a power source, the current sensor output is applied to the current sensor before the battery is applied to the device, and the output of the current sensor when the drive power is applied is actually offset. The value is regarded as a value, and the offset correction is performed so that the sensor output at that time becomes zero.

Further, the present invention is a battery remaining capacity measuring device in which a current sensor detects a charging current of a battery and accumulates the charging amount to obtain the remaining capacity of the battery. The power supply for driving the current sensor is applied prior to the start of battery charging by the, and the output of the current sensor when the power supply for driving the current sensor is applied is taken as the actual offset value. The offset correction is performed so that the sensor output at that time becomes zero.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a drive motor M for an electric vehicle.
2 shows an example of the configuration of the power supply circuit system of FIG.

The operating state of the power supply circuit system will be described below.

FIG. 2 shows the towing of the operation of each part when the automobile is running.

When the main switch M.SW is closed at time t1 when the vehicle is traveling, the 12V auxiliary battery 3 is put into the controller 2. Controller 2
Turns on the DC / DC converter 5 by energizing the relay 4 to close its relay contact R1-a after a lapse of time of about 100 mS. As a result, the DC / DC converter 5 reduces the voltage of the main battery 1 of 60V to 12V, applies the converted voltage of 12V to the auxiliary battery 3, and supplies the power. Next, the controller 2 detects the terminal voltage of the main battery 1 detected by the voltmeter 6 and the DC / DC converter 5
After checking the output voltage of 1 to check if there is no abnormality, if there is no abnormality, the relay 7 is energized to close the relay contact R2-a at time t4, and then the predetermined value set by the internal timer. After a lapse of time, an electromagnetic breaker switch 8 provided in the main power supply circuit at time t5
To turn on. As a result, the main battery 1 is put into the driver 9 and the motor M becomes drivable.

By closing the relay contact R2-a prior to turning on the breaker switch 8 provided in the main power circuit, an excessive rush current flows into the surge absorbing resistor R and is absorbed. After that, the breaker switch 8 is turned on to protect the contact.

When the driving of the automobile is completed and the main switch M.SW is opened, the driver 9 is turned off and the relay 7 is deenergized and the relay contact R2 is controlled under the control of the controller 2. -A and the breaker switch 8 are opened, then the relay 4 is de-energized and the relay contact R1-a is opened, and the DC / DC converter 5 is turned off.

FIG. 3 shows the operation of each part when the main battery 1 is charged.

When charging the main battery 1 when the main switch M.SW is opened and the vehicle is in a stopped state, when the power plug 10 is inserted into an AC 100V outlet at time t1, the charger 11 causes the main battery 1 to be charged. Output voltage 5 of the first stage to the extent that current is not supplied to
It rises to 0V. As the main battery 1, when it is in a fully charged state, the terminal voltage becomes 65V,
When it is half charged, the terminal voltage is 62.
It becomes 5V, and when it is in an empty charge state, the terminal voltage is 5V.
It is over 5V. Then, at time t2 when the output voltage of the charger 11 rises to 50V, the DC / DC converter 5 is turned on, and the output thereof rises to a predetermined level t.
An output voltage of 12 V is applied from the DC / DC converter 5 to the controller 2 at three points. Next, the controller 2 includes the charger 11 and the DC / DC converter 5
After checking that both of them are in the ON state, the output voltage of the charger 11 is gradually increased to 85V to start charging the main battery 1 at time t5, and constant current control is performed to perform constant current control. Charge 1

In the present invention, in the power supply circuit system of the drive motor M in such an electric vehicle, the current sensor 12 is provided in the charging circuit of the main battery 1 by the charger 11.
And a current sensor 13 provided in the main power supply circuit to which the main battery 1 is connected during traveling, and the controller 2 integrates the charging current of the main battery 1 detected by the current sensor 12 to obtain the charge amount and the current sensor. The remaining capacity of the main battery 1 is obtained from the discharge amount obtained by integrating the discharge current of the main battery 1 detected by 13.

That is, the controller 2 reads the sensor output from the current sensor 12 at the time of charging the main battery 1, detects the value of the charging current of the main battery 1, integrates the charging amount, and integrates it. The result of adding the charge amount to the remaining capacity of the main battery 1 before the charge is stored in the internal memory. Then, the controller 2 reads the sensor output from the current sensor 13 to detect the value of the discharge current of the main battery 1 during the subsequent traveling of the vehicle, integrates the discharge amount, and is stored in the internal memory. The remaining capacity of the main battery 1 is sequentially obtained by subtracting the discharge amount accumulated up to the charge amount.

At this time, as described above, in order to accurately determine the remaining capacity of the main battery 1, the current sensors 12, 13 are used.
It is necessary to perform temperature compensation of each sensor output in.

For example, when the change of the running environment of the automobile is remarkable and the temperature fluctuation is in the range of, for example, -20 ° C to + 60 ° C, it is necessary to consider the temperature fluctuation of 80 degrees as a sensor error.

FIG. 6 shows the input / output characteristics of the current sensor.

Now, for example, when the input current I of the current sensor 13 changes in the range of -50A to + 100A while the automobile is running, the fluctuation range of the input current I becomes 150A and the fluctuation range of the output voltage E becomes 4A. .5V-0.5V = 4
V, and the output voltage E at that time is given by the following equation.

E = (4V / 150A) I + a (1) where α is an offset voltage, where α (s) is the offset voltage at room temperature (20 ° C.) and α is the offset voltage at t ° C. When (t), α = α (s) + α
(T). Further, α (s) is about 1.833 V, but there are variations depending on each sensor.

Similarly, when the main battery 1 is charged and the input current I of the current sensor 12 changes in the range of -10A to + 20A, the output voltage E of the current sensor 12 is given by the following equation.

E = (4V / 30A) I + α (2)

Therefore, α in equations (1) and (2)
Since the term varies depending on the variation of each sensor and the temperature change, it is necessary to perform the offset correction.

Therefore, in the present invention, every time the vehicle starts to run, the breaker switch 8 is closed and the main battery 1 is put into the driver 2 of the motor M under the control of the controller 2 at the time of running. Prior to this, the current sensor 13 is supplied with its driving power supply, and offset correction is performed each time such that the sensor output when the driving power supply is supplied becomes zero.

Further, according to the present invention, each time the main battery 1 is charged, the current sensor is charged under the control of the controller 2 before the main battery 1 is charged by the charger 11 at the time of charging. 12 is supplied with the driving power supply, and offset correction is performed each time such that the sensor output when the driving power supply is supplied becomes zero.

Specifically, as shown in FIG. 2, at the time of t1 when the main switch M · SW is closed and the auxiliary battery 3 is put into the controller 2 when the vehicle is traveling, a command from the controller 2 is issued. The power supply for driving is supplied to the current sensor 13, and the controller 2 outputs the output voltage of the current sensor 13 at time t2 when the current power supply 13 is turned on and the operating state of the current sensor 13 rises after about 10 ms. The value is read and stored as an offset value in the internal memory until time t3 when the DC / DC converter 5 is turned on.

Then, after the time t5 when the breaker switch 8 is closed and the main battery 1 is turned on to the driver 9 of the motor M, the controller 2 outputs each output voltage value sequentially read from the current sensor 13 at a predetermined cycle. Then, the offset value stored in advance is subtracted to correct the offset of the sensor output.

FIG. 4 shows a flow of control contents in the controller 2 until the main battery 1 is put into the drive motor M of the vehicle while the vehicle is running.

Further, as shown in FIG. 3, when the main battery 1 is charged, the output voltage of the DC / DC converter 5 rises to a predetermined level and the controller 2 is turned on.
At time t3, the power supply for driving is supplied to the current sensor 12 according to a command from the controller 2, and when the power supply for driving the current sensor 12 is turned on, the current sensor 12 is activated after a lapse of time of about 10 mS. Then, the controller 2 reads the output voltage value of the current sensor 12 and stores it in the internal memory as an offset correction value until time t5 when the charging of the main battery 1 by the charger 11 is started.

Then, the controller 2 calculates each output voltage value sequentially read from the current sensor 12 at a predetermined cycle when the main battery 1 is charged after the time t5.
The offset value of the sensor output is corrected by subtracting the previously stored offset value.

FIG. 5 shows a flow of control contents by the controller 2 until the charging of the main battery 1 is started.

Here, the controller 2 checks whether or not the charger 11 or the DC / DC converter 5 has risen to the ON state, and when it does not rise, the charger 11 or the DC / DC converter 5 is judged to be abnormal. It is considered that it has come, and abnormal processing such as issuing an alarm to that effect is executed.

Further, the controller 2 reads the terminal voltage of the main battery 1 and checks whether it is 50 V or less, and if it is 50 V or less, it is considered that the main battery 1 is short-circuited. , Execute abnormal processing such as issuing an alarm to that effect.

As described above, according to the present invention, every time when the running of the automobile or the charging of the main battery 1 is started,
An offset that is caused by variations in individual sensors in the current sensor 13 or 12 that detects the discharge current or the charging current of the main battery 1 without causing any trouble in the control of running or charging, and that depends on the temperature at the time of detection. The value can be actually obtained each time, and the offset correction of the sensor output after the start can be properly performed.

Therefore, only the temperature variation during the running of the automobile or the charging of the main battery 1 is the error factor of the sensor output, but in reality, the temperature variation during the running is small in the operating temperature range. Therefore, the remaining capacity of the main battery 1 can be accurately obtained.

In particular, since an automobile rarely travels without stopping all day long, the offset value of the current sensor 13 is obtained each time the vehicle restarts after the stop, and the sensor corresponding to the temperature change is obtained. The output offset correction can be frequently performed.

Even while the vehicle is running, the controller 2 monitors the driving state of the vehicle and detects that the vehicle is temporarily stopped by waiting for a signal,
At the time of detection, the main battery 1 may be removed from the driver 9 of the motor M, and the above-described control for starting traveling may be performed to obtain the offset value of the current sensor 13 at that time. It is possible.

In this case, the change may not be corrected immediately, but the temperature change of the internal thermometer may be checked to determine whether or not to correct.

[0045]

As described above, in the battery remaining capacity measuring device according to the present invention, the discharge current of the battery is detected by the current sensor and the discharge amount is integrated, and the charge current of the battery is detected by the current sensor. Then, when calculating the remaining capacity of the battery by integrating the charged amount, the offset correction of the sensor output according to the variation of the characteristics of each current sensor and according to the temperature at that time should be made appropriate in practice. Therefore, there is an advantage that the remaining capacity of the battery can be accurately measured.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an example of a power supply circuit system of a drive motor in an electric vehicle.

FIG. 2 is a timing chart of the operation of each part when the vehicle is traveling.

FIG. 3 is a timing chart of the operation of each part during charging of the main battery.

FIG. 4 is a flowchart showing the control contents of the controller until the main battery is inserted into the drive motor of the automobile while it is traveling.

FIG. 5 is a flowchart showing the control contents by the controller until the charging of the main battery is started.

FIG. 6 is a diagram showing input / output characteristics of a current sensor.

[Explanation of symbols]

 1 Main Battery 2 Controller 3 Auxiliary Battery 5 DC / DC Converter 8 Breaker Switch 9 Driver 11 Charger 12 Current Sensor 13 Current Sensor

Claims (2)

[Claims] 1. A battery remaining capacity measuring device, wherein a current sensor detects a discharge current of a battery and integrates the discharge amount to obtain the remaining capacity of the battery, and when starting equipment using the battery as a power source, Offset correction is performed so that the output of the current sensor when the power supply for driving the current sensor is applied and the output of the current sensor becomes zero before the battery is input to the device. A method for measuring the remaining capacity of a battery, characterized in that a means for causing the remaining capacity is taken. 2. A battery remaining capacity measuring device in which a battery current is detected by a current sensor and the remaining capacity of the battery is obtained by integrating the charged amount of the battery. When charging the battery, the battery is charged by a charger. Means for supplying the current sensor with its driving power source prior to the start of the current sensor, and means for performing offset correction so that the output of the current sensor when the current sensor is supplied with the driving power source becomes zero. A battery remaining capacity measuring device characterized by being adapted to take.