JP2002107428A - Current/frequency converter and chargeable battery and chargeable battery pack having the same built-in - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a C/F converter having a large dynamic range and a good linearity, and to provide a chargeable battery and a chargeable battery pack capable of highly accurately calculating the present discharge current value, the amount of an accumulated discharge and the like using an A/D conversion circuit by means of this converter. SOLUTION: A correction circuit is provided for a current to current conversion having a characteristic for correcting a non-linear area by a straight line or by an approximately straight line for a current frequency conversion characteristic having the non-linear area for an increase in an input current to a mirror integrating circuit. Inputting the current for the frequency conversion into the mirror integrating circuit through the correction circuit allows the frequency conversion having a high accuracy in a wide range of detecting current values. For the rechargeable battery or the rechargeable battery pack using such a C/F converter, the number of pulses corresponding to the number of completion of integration in an integrating capacitor in the mirror integrating circuit is indicated as the count value for a counter, so that it is possible to calculate the current value corresponding to the amount of a charge including a transient current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current / frequency converter (hereinafter referred to as C / F converter) and a rechargeable battery or rechargeable battery pack containing the same.
In a lithium-ion secondary storage battery (hereinafter referred to as a lithium battery) having a controller for charge / discharge control or its rechargeable battery pack, the current discharge current value, integrated discharge amount, and the like are measured using an A / D conversion circuit using a C / F converter. The present invention relates to a rechargeable battery and a rechargeable battery pack that can be calculated with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a rechargeable battery such as a lithium battery and a rechargeable battery pack (hereinafter referred to as a rechargeable battery) are built in an electronic device such as a portable computer or a handheld electronic device, and the voltage of the rechargeable battery is lower than a predetermined value. Then, the charging is performed by the charging circuit of the electronic device, the charging current is received, the charging is terminated when the charging is completed, and the battery is discharged to supply power to the electronic device when the battery is driven. For this purpose, the controller for charge / discharge control switches a current direction by providing a switch circuit (relay or relay device) that allows current to flow bidirectionally between the positive electrode side of the rechargeable battery and the charging terminal. In addition, there is a diode switching circuit that inserts a diode in series in each of the charging and discharging directions to select a current in one direction and block a current in the opposite direction. In an electronic device having this type of rechargeable battery, A
When the electronic device is not operating or connected to the C power source, the rechargeable battery is charged. When the AC power source is removed and the electronic device is operated, power is supplied from the rechargeable battery. The electronic device operates.

Recently, a battery according to the smart battery standard has been developed and used as a battery built in this kind of electronic device. According to this smart battery standard, a processor (MPU) in an electronic device and a controller having a processor provided as an internal circuit in a rechargeable battery are connected by an SM bus, and the state of the rechargeable battery is determined by a processor (MPU) in the electronic device. Can be sent out as data. One of the data transferred as the state of the battery includes data such as the integrated discharge capacity of the rechargeable battery, the current discharge current value, and the remaining capacity (remaining capacity).

[0004]

Conventionally, in a battery according to the smart battery standard, when the integrated discharge capacity of the rechargeable battery, the current discharge current value, the remaining amount, and the like are sent to the electronic device side, a predetermined cycle is required. And the A / D conversion of the discharge current value to obtain the used charge amount (used discharge amount) from the used current value from the time of full charge to the present. For the remaining amount, the obtained used charge amount is converted to a total discharge capacity up to a preset discharge end voltage (for example, a fixed total discharge capacity when the voltage of the rechargeable battery becomes 3.0 V). It is obtained by subtracting from the capacitance value Qo).

Incidentally, the discharge current value, the accumulated discharge charge amount, the remaining amount, and the like are affected by the current detection accuracy of the current value. If this current value is to be A / D converted from a small current value of several mA to several tens A to a large current value, an A / D conversion circuit having a large number of digits and a high accuracy is required, and it is not expensive. Not get. Furthermore, considering the transient current, the range of the detected current value is
From 1 mA to 100 A. On the other hand, as inexpensive counting A / D converters, VN converters and VF converters, and those using a counting circuit together with these converters are known.
Since the VN converter and the VF converter generally adopt a form in which a voltage-current conversion element or a voltage-current conversion circuit is provided at the input of the C / F converter, the C / F converter portion is used to convert the detected current value. It can be used, but has the disadvantage of a small conversion dynamic range. If this is used by increasing the conversion dynamic range, a non-linear region will be used, and there is a problem in converting the current value of the rechargeable battery. FIG. 9 shows an example of a conventional C / F converter 30. A mirror integrating circuit 31 for mirror-integrating the input current value, a voltage comparator 32, and a reset circuit including a buffer amplifier 33 and a switch circuit 34;
The switch circuit 34 connected in parallel to the integrating capacitor C of the Miller integrating circuit 31 is turned on for a certain period by the output of the buffer amplifier 33 receiving the output of the voltage comparator 32 to discharge and reset the capacitor C. 31a is an operational amplifier circuit of the Miller integrating circuit 31, 3
An input current source 5 generates a discharge current having a predetermined value as an integrated current. Reference numeral 36 denotes a comparison reference voltage power supply, which generates a constant negative voltage as a comparison reference. 37 is
An output terminal that generates a pulse.

In such a C / F converter 30, the capacitor C is discharged according to the cycle of the output pulse of the voltage comparator 32 until the next pulse is generated. Therefore, as the converted frequency increases, the cycle of the output pulse becomes shorter, and the reset period of the capacitor C cannot be secured before long, and the next charge is started for the capacitor C that has not been completely discharged. Therefore, there is a problem that the period of the next output pulse becomes shorter with respect to the input current value, and a linear conversion relationship cannot be maintained with respect to frequency conversion in a direction in which the frequency increases. Therefore, the conversion dynamic range in which linearity can be ensured is narrow. In order to avoid such a situation, a one-shot circuit is provided instead of the buffer amplifier 33, and the capacitor C
If the reset period is sufficiently secured, the frequency will not be proportional to the current value even if the current value increases at a frequency close to the reset period, but will be lower. In addition, the dynamic range of the convertible frequency is reduced. Therefore, it is difficult to apply to the A / D conversion circuit of the current value of the rechargeable battery or the rechargeable battery pack requiring a large dynamic range as described above. SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem of the prior art, and to provide a C / F converter having a wide dynamic range and a higher linearity. Still another object of the present invention is to use an A / D conversion circuit by a C / F converter to obtain the current discharge current value,
An object of the present invention is to provide a rechargeable battery and a rechargeable battery pack capable of calculating an integrated discharge amount and the like with high accuracy.

[0007]

A feature of the C / F converter according to the present invention for achieving the above object is that the C / F converter comprises a Miller integrating circuit and a voltage comparator, and converts a current input to the Miller integrating circuit into a Miller integrating circuit. The voltage is integrated by a circuit and compared with a reference voltage of a voltage comparator. An output pulse is generated from the voltage comparator. In accordance with the output pulse, the charge of the integrating capacitor of the Miller integrating circuit is discharged and reset. Current / frequency converter that repeats the above equation, the current-to-current characteristic has the characteristic of linearly correcting or linearly approximating the non-linear region with respect to the current frequency conversion characteristic having the non-linear region with respect to the increase in the input current of the Miller integrating circuit. A conversion correction circuit is provided, and a current for frequency conversion is input to a Miller integration circuit via the correction circuit. A. The rechargeable battery or rechargeable battery pack according to the present invention using such a C / F converter is characterized in that the C / F converter having the above-described configuration and a current value corresponding to a charge current value or a discharge current value of the rechargeable battery body. , A current value detection circuit for generating a detection signal for input to the correction circuit of the C / F converter, a counter for counting the output pulses of the C / F converter, and reading the value of this counter at a predetermined cycle. A control circuit for calculating at least one of a charge current value, a discharge current value, a charge amount of the charge battery body, and a discharge charge amount of the charge battery body from the values.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the current frequency conversion characteristic having a non-linear region with respect to the increase of the input current of the Miller integrator circuit has the characteristic that the non-linear region is linearly corrected or linearly approximated. A current-to-current conversion correction circuit is provided, and a current for frequency conversion is input to the Miller integrator circuit via this correction circuit. Therefore, the frequency of the output pulse of the voltage comparator is linearized with respect to the input current value of the correction circuit. Can be associated with. As a result, frequency conversion can be performed with high accuracy in a wide range of the detected current value. As a result, a large dynamic range can be obtained, and a C / F converter can be realized with higher linearity. In a rechargeable battery or a rechargeable battery pack using such a C / F converter, the number of pulses corresponding to the number of times the integration of the integrating capacitor of the Miller integrator is completed appears as the count value of the counter. The number of times of integration completion × one integrated charge represents the total charge during a certain period. Even if the current transiently increases, the number of integration completions is corresponding to the number of integrations. Therefore, the number of pulses of the C / F converter in a certain period corresponds to the number of times × 1 integrated charge amount. That is, the number of passes in a certain period represents the total charge amount in a certain period. As a result, C /
In the digital conversion of the pulse number by the F converter, a current value corresponding to the charge amount of the battery including the transient current can be calculated. Therefore, a current value closer to the actual analog charge amount can be obtained in the form of a digital value than in a case where a detected value sampled at that time is converted to a digital value as in a normal A / D conversion. Current value detection and calculation of the integrated charge amount.

[0009]

FIG. 1 is a circuit diagram of an embodiment to which the C / F converter of the present invention is applied, and FIG. 2 is an embodiment of a rechargeable battery incorporating the C / F converter of FIG. Circuit diagram focusing on lithium rechargeable battery built in the device, FIG. 3
FIG. 3A is an explanatory diagram of an example of a sub-threshold characteristic of an n-channel MOSFET transistor as a logarithmic amplification characteristic of a C / F converter, and FIG. 3B is an explanatory diagram of a polygonal line correction characteristic by a polygonal line function generator; 4, Fig. 5
FIG. 9 is a circuit diagram of another embodiment to which the C / F converter of the present invention is applied. In FIG. 1, reference numeral 40 denotes a C / F converter, which converts the current value into a voltage value by an inverting operational amplifier 41a which receives the current value sinking as a detection signal from the current value detection circuit 4 on the (-) input terminal side. The output voltage is amplified and input to the gate of the n-channel MOSFET transistor Tr1, and the source side is logarithmically amplified according to the exponential function according to the gate voltage using the exponential function characteristic between the gate and the source. Generated current value. Here, the operational amplifier 41a forms a current-voltage conversion circuit 41, has a feedback resistor Rf connected from the output side to the (−) input terminal side, and detects the detected current value of the current value detection circuit 4 It is converted to a control voltage value in the range of 0V to 1.5V. Note that the current value detection circuit 4 generates a detection signal of a current value corresponding to the charging or discharging current value of the rechargeable battery.

The current value logarithmically amplified by the transistor Tr1 is supplied to the operational amplifier 4 via current mirrors 42 and 43.
The current is transferred to the (-) input terminal of the Miller integrating circuit 44 having 4a. In the current mirror 42, the emitter area ratio between the input transistor Tr2 and the output transistor Tr3 is different, and the output transistor Tr3 is n times as large. Similarly, in the current mirror 43, the input transistor Tr4 and the output transistor Tr5 have different emitter area ratios, and the output transistor Tr5 is n times as large. The transistor Tr1 has an output current value of pA to
As a region of μA, the drain current ID flows in a weak inversion region in which the gate voltage changes exponentially with respect to VG. The current in the sub-threshold characteristic is taken as an amplified current and taken out and amplified by a current mirror circuit. FIG. 3 shows an example of the characteristic. As a result, the current value of the detection signal of the current value detection circuit 4 is temporarily set to 0 V by the current-voltage conversion circuit 41.
To 1.5V, logarithmically amplify and current mirror 4
In steps 2 and 43, the value is multiplied by n × n and converted into an integrated current value for the mirror integrating circuit 44. As a result, a current value of one hundred pA to tens of μA is obtained as the integration current value of the integration capacitor C.

In the mirror integration circuit 44, the current value i of 100 pA to tens of μA amplified by the current mirror is input to the (-) input terminal as a sink current, and the (-) input terminal of the inversion type operational amplifier 44a. The integration capacitor C connected to the output and the output is charged with the output current corresponding to the input current value. Then, the charging voltage of the capacitor C is set to the comparator 4
5 (+) input terminal and the comparator 45
In this case, when it exceeds the reference voltage Vref of the reference power supply 46 on the (-) input terminal side, a HIGH-level ("H") pulse is generated at the output,
Is applied via a buffer amplifier 33 to a switch circuit 34 of a transfer gate (analog switch) provided in parallel with the switch C, and is turned on, and the charge stored in the capacitor C is discharged and reset. At this time, an output pulse is generated at the output terminal 47 of the comparator 45 at the same time. By repeating such charging / discharging, a pulse of a frequency corresponding to the charging current of the capacitor C, that is, the input current is output from the comparator 45 to the output terminal 47.

Here, in the C / F converter 40,
If the value of the integrating capacitor C is 10 pF and the switch circuit 34 is a C-MOS transfer gate, the ON resistance is about 1 kΩ, and the range of the charge / discharge detection current value is 1
mA to 100 A. At this time, each detected current value and the integrated current value are linearly associated with each other, and when the current is 1 mA, the current value flowing through the integrating capacitor C in the Miller integrating circuit 44 is set to 1
It is assumed that a current of 15 μA flows when the detection current value is 50 pA and the detection current value is 100 A. The output frequency at this time is also made to correspond linearly to 10H when the integrated current value is 150 pA.
z, when the integrated current value is 15 μA, 1 MHz and 10
It is assumed that the frequency is set in a range from Hz to 1 MHz. In this case, the error when there is no correction circuit by the transistor Tr1 is as follows: When the detection current value of charging and discharging is about 1 mA to 10 mA,
It can be ignored because it is 0.01% or less, but 10%
At about 0 mA, it becomes about 0.02%, at about 1A, 0.2%, at 10A, 2%, and at 100A, 1%.
It is as large as about 7%. By providing the correction circuit using the transistor Tr1, the error has the characteristic shown in FIG. 8A and can be suppressed to within 1%. In this figure, a characteristic graph 50 is a characteristic when no correction circuit is provided, and a characteristic graph 51 is an example of a characteristic when a correction circuit using the transistor Tr1 is inserted.

FIG. 2 is an explanatory diagram of a rechargeable battery utilizing the C / F converter 40. In FIG. 2, 20 is
The electronic device includes a rechargeable battery 10 having a charge / discharge control circuit in a battery detachably mounted therein. The rechargeable battery 10 includes a plurality of (three in the figure) lithium battery cells (hereinafter referred to as battery bodies) 1a, 1b,..., 1n, and a battery pack connected in series. 22, a charge / discharge terminal 14a (connector connection terminal), a charge / discharge power supply line + Vcc (hereinafter, power supply line + V
cc), the charging current is received via the charge / discharge changeover switch circuit 13, and the device main body 21 is supplied with power by the discharging current from the battery main body side via the charging / discharging terminal 14a. Also,
The rechargeable battery 10 includes an MPU 23 provided in the apparatus main body 21.
Thus, the current charge or discharge current value of the rechargeable battery 10, the integrated discharge amount, the remaining amount of the battery, and the like are read out or transmitted via the SM bus 12. In addition, power supply line + Vcc
Are connected to the charging / discharging terminal 14a, and are connected to the apparatus main body 21 via this. Also, the ground line GND
L is connected to the ground terminal 14b (connector connection terminal), and through this is connected to the ground GND of the apparatus main body 21.

The switch circuit SW includes a power supply line 10a of the rechargeable battery 10 (a line for supplying power to each circuit including the MPU 6 from the positive electrode side of the battery body 1a) and a receiving power supply terminal (+ Vc) for receiving the operating power of the MPU 6. ), A switch circuit inserted between the power supply terminal (+ Vc) of each circuit. The switch circuit SW is a switch that operates in conjunction with the charge switch of the charge / discharge changeover switch circuit 13, and is in an initial state and when the charging is performed, the apparatus main body 2
It is turned on according to the charging voltage of the charging circuit on the first side. Unlike the charge switch of the charge / discharge changeover switch circuit 13, once turned ON, this switch SW is kept ON.
Then, the control signal S generated from the MPU 6 under specific conditions
OFF when receiving

Incidentally, the built-in circuit built in the rechargeable battery 10 described here is usually constituted by CMOS or the like.
A low power consumption type circuit is used. The operating power is very small, and the built-in circuit here operates on the power from the rechargeable battery except when it is in a charged state.
Further, the detection of the full charge when the rechargeable battery 10 is fully charged determines whether the terminal voltage of the battery body is a predetermined value corresponding to the full charge,
It is detected when the voltage becomes higher, for example, when the voltage becomes 4.3 V. The SM bus 12 includes a data line signal line DATA and a clock line CLK for connecting the interface 24 of the device body 21 with the bus 11, and is connected to the interface 24 of the device body 21 via connector connection terminals 12a and 12b. ing. Data line signal line D
ATA and clock line 12b are connected to resistors R1 and R2, respectively.
Is pulled down to the ground GNDL. The corresponding connection lines on the interface 24 side are pulled up to the power supply line + VDD on the device body 21 side by resistors R3 and R4, respectively.

The power supply circuit 22 includes a rechargeable battery 10 and a commercial AC
It has a switching circuit with the power supply,
The power from the power supply is supplied, and the apparatus main body 21 operates.
A charge / discharge changeover switch circuit 1 provided between a positive electrode of a battery body 1a of a rechargeable battery 10 and a power supply line + Vcc.
Reference numeral 3 denotes a charge-side switch and a discharge-side switch. The charge-side switch and the discharge-side switch are turned on and off by the controller 2 in response to charging and discharging.
F control is performed. The charge / discharge changeover switch circuit 13
May be deleted, and the charge / discharge power supply line + Vcc may be directly connected to the positive electrode side of the battery body 1a. Inside the rechargeable battery 10, in addition to the controller 2, a voltage detection circuit 3, a current value detection circuit 4, and a temperature detection circuit 5 are provided. The voltage detection circuit 3 includes battery bodies 1a, 1b,
, 1n are connected to the positive electrode side and the negative electrode side, respectively, and detect the respective terminal voltages and output the current voltage value of the battery body to the controller 2 according to the control signal from the controller 2. When any one of the battery bodies 1a, 1b,..., 1n is overcharged or overdischarged in accordance with the detected voltage value, the controller 2 controls the charge / discharge changeover switch circuit 13 to overcharge the battery. Then, the switch on the charging side is turned off, and the switch on the discharging side is turned off at the time of overdischarge, thereby stopping the charge / discharge operation.

The current value detection circuit 4 has a detection resistor Rs, which is inserted in series between the negative electrode of the battery body 1n and the ground line GNDL. The current value of the current value detection circuit 4 is converted into a pulse frequency by the C / F converter (C / F) 40 described with reference to FIG. 1, and counted by the counter 8a. This gives A /
The D value is converted, and the count value is periodically read by the MPU 6 via the bus 11. The temperature detection circuit 5 has a temperature sensor (not shown), and receives a signal from the temperature sensor and outputs a current temperature value to the controller 2 according to a control signal from the controller 2. The controller 2 includes an MPU 6, a memory 7, an A / D conversion circuit 8, a display device 9a, a timer 9b, and the like. These circuits are interconnected via a bus 11. Further, each control signal is sent to each circuit via the bus 11.
Then, the detection signal values of the voltage detection circuit 3 and the temperature detection circuit 5 are passed to the MPU 6 via the A / D 8. The timer 9b generates a timer interrupt signal every time Δt, for example, every 0.1 seconds. When the MPU 6 is in a sleep state, the timer 9b starts the MPU 6 by the timer interrupt signal to start a main program and execute various types of operations described below. MPU processing
6 is executed.

The memory 7 has a current value calculation program 7a
And an integrated discharge amount calculation program 7b, a remaining amount calculation program 7c, a data transfer program 7d, a storage area (parameter area) 7e for parameters and the like, and a detection number counter 7f (so-called soft counter). The parameter area 7e includes parameters such as the number-of-times-of-charging count value N and the reference total discharge capacity value Qo, the count value of the counter 8a, ten pieces of detection data as the current value, and whether the rechargeable battery 10 is currently being charged. , Discharging,
A 2-bit status flag indicating which one of the sleep states is set is stored. Here, the current value calculation program 7a receives an interrupt signal every 0.1 second by the timer 9b, and is executed by the MPU 6 in response thereto.
When this program is executed by MPU6,
The value of the counter 8a is read via the bus 11, and the counter 8a is reset. Then, referring to the number-of-detections counter 7f, when the value is 10 or less, the read count value is multiplied by 10 to obtain a frequency per second, which is converted into a current value and stored in the parameter area 7e. This is 10
When the value of the counter 7f is 10 after repeating the number of times,
The average value of the ten detected current values is calculated and the current value I is calculated.
Is stored in the parameter area 7e, and the value of the detection counter 7f is cleared to "0". Thereby, 0.1 seconds x
With 10 = 1, the average current value corresponding to the frequency for one second is obtained as the current detection current value. Next, the storage area 7e
When the discharge is being performed with reference to the flag (3), the integrated discharge amount calculation program 7b is called and the MPU 6 executes the program.

The integrated discharge amount calculation program 7b executes the MPU 6 after the execution of the current value calculation program 7a during discharge.
The discharge amount from the time of full charge to the present time is calculated from the current discharge charge amount ΔQ to the discharge capacity Qn-1 integrated up to the previous time with the current value I calculated every second as the discharge charge ΔQ. Is calculated and stored in the memory 7. In addition, the remaining amount calculation program 7
Calculation of the remaining amount of the battery or the like is performed using c, but this is omitted. The data transfer program 7d is executed by the MPU 6 when the MPU 6 receives a request signal from the device body 21 via the SM bus 12 as an interrupt signal and returns from the sleep state. When this is executed, the flag in the parameter area 7e is changed from sleep to active, and the content of the request signal sent from the apparatus main body 21 together with the interrupt signal is analyzed or decoded. , The current value I stored in the parameter area 7e is read out and sent to the apparatus main body 21. When the content of the request signal is the integrated discharge amount up to the present, the integrated value Qn up to the current stored in the parameter area 7e is obtained. To read out the device body 2
Send to 1.

FIG. 4 shows the C / F converter 40a of FIG.
Is provided with an NPN-type bipolar transistor Q1 in place of the current-voltage conversion circuit 41 and the transistor Tr1,
The emitter is grounded to form a logarithmic amplifier using an exponential function characteristic region between the base and the emitter. The logarithmic amplifier amplifies an input current to generate an integrated current value. In this embodiment, a high-precision current mirror 42a in which the base current is corrected by the transistor Q4 instead of the current mirrors 42 and 43 of FIG.
(A current mirror composed of bipolar transistors Q2 and Q3) is provided to obtain an n-fold output current from the transistor Q3, which is input to the (-) input terminal of the Miller integrating circuit 44. Other configurations are the same as those in FIG. 1, but the reference voltage power supply 46 has a negative voltage −Vref, contrary to the case of FIG. In this embodiment, the detection signal from the current value detection circuit 4 is not a current value to be synced but a normal discharge current. FIG. 8 shows the conversion characteristics.
(B) Show. In FIG. 8B, a graph 52 is a characteristic before correction, and a graph 53 is a characteristic after correction.
By this correction, the error from about 0 mA to 10 A can be suppressed to about 1% or less. The C / F converter 40b shown in FIG. 5 includes a logarithmic amplifier using the transistor Tr1 and the current mirrors 42 and 43 shown in FIG.
And a line function generator 48 of an operational amplifier 47 and an input resistor R to the (-) input terminal of the Miller integrating circuit 44. The polygonal line characteristic of the polygonal line function generator 48 is as follows.
This is a characteristic bent at one place. After the input current is converted into a voltage by the current-voltage conversion circuit 41, the converted current is converted into a voltage having a polygonal line characteristic as shown in FIG. The input voltage is converted into a current value by the input resistor R, and is input to the (-) input terminal of the virtual short-circuit Miller integration circuit 44. It should be noted that the reference voltage power supply 46 has a negative voltage −Vref, contrary to the case of FIG.

As described above, the error when there is no correction circuit using the transistor Tr1 in FIG. 1 is 0.01% when the charge / discharge detection current value is about 1 mA to 10 mA.
It is negligible because it is less than that, but when it is about 100 mA, it is about 0.02%, and when it is about 1 A, it is 0.2
%, 2% at 10A, and about 17% at 100A. Therefore, in the C / F converter 40b of FIG. 5, the range of 0 mA to 1 A is regarded as a straight line, and
The above-mentioned error characteristic can be approximated and corrected by a two-part straight line with the straight line of A. As a result, highly accurate detection can be performed up to about 0 mA to several tens of amps. By setting such an approximate straight line as a broken line by the broken line function generator 48 in FIG. 5, characteristics as shown in FIG. 8C can be obtained. In FIG. 8C, a graph 54 shows the characteristics before correction, and a graph 55 shows the characteristics after correction. By this correction, the error from about 0 mA to 10 A can be suppressed to about 1% or less. .

FIG. 6 shows a C / F converter 40c of still another embodiment, in which the reset period of the integrating capacitor C is set by a one-shot circuit, and the charge current value and the discharge current value are the same circuit. This is an embodiment in which detection is performed. The same elements as those in FIGS. 1 to 5 are denoted by the same reference numerals. In FIG. 6, the detection resistor R
Assuming that s = 20 mΩ, the input current is converted into a voltage by the current-voltage conversion circuit 41, and then input to the (−) input terminal of the Miller integration circuit 440 via the broken line function generator 48 shown in FIG. The Miller integrating circuit 440 here has an operational amplifier 440a whose (+) input terminal side is set to a reference voltage of 2.5 V, a 10 pF capacitor is provided as an integrating capacitor C, and the ON circuit is used as a switch circuit 34. A transfer gate having a resistance of 1 kΩ is provided. The output of the operational amplifier 440 is input to the (+) input terminal of the comparator 45a on the charge current value detection side, and is input to the (−) input terminal of the comparator 45b on the discharge current value detection side. A reference voltage of +4 V is applied to the (−) input terminal side which is a reference voltage input of the comparator 45a, and a + 1V reference voltage is applied to a (+) input terminal side which is a reference voltage input of the comparator 45b. I have.

The output of the comparator 45a is applied to the up-count terminal U of the up / down counter 80, and the output of the comparator 45b is applied to the up / down counter 80.
To the down-count terminal D. The output of each of the comparators 45a and 45b is
The signal is sent to the one-shot circuit 33b via 3a. Here, the rise time of the switch circuit 34 to ON and the OF time
If the total value of the maximum value of the fall time to F is 200 nsec and 50 nsec is required as the reset period of the capacitor C, if half of the rise and fall periods do not contribute to the charge discharge, the reset is performed. Period is 1
Since the reset period is set to 50 nsec, the reset period set in the one-shot circuit 33 b is set to 200 nsec with a margin of 50 nsec.
sec. The charging characteristic of the capacitor C in such a circuit has a waveform as shown in FIG. Note that the waveform shown by the solid line is during charging, and the waveform shown by the dotted line is during discharging. The up / down counter 80 is provided in place of the counter 8 a in FIG. 2 and is connected to the bus 11. Then, the data is read by the MPU 6 every 0.1 second, reset, and restarted. At the time of charging, the output pulse of the comparator 45a is counted, and at the time of discharging, the output pulse of the comparator 45b is down-counted. The MPU 6 calculates the current value from the count value as a discharge current value when the count value is a negative count value (or a complement value) and as a charge current value when the count value is a positive count value.

By the way, the C / F converter 4 of the embodiment
In each of 0, 40a, 40b, and 40c, the output pulse is received by a counter, and the counter is counted at regular time intervals to obtain a frequency. As described above, in the A / D conversion in which a pulse value is counted by a counter for a predetermined time and obtained as a frequency, a transient current at power-on, for example, about 100 A, or a pulse current at the time of device driving, for example, about 10 A The current value per second and the total charge amount can be reduced by the normal A / D
It can be detected more accurately than the conversion circuit. For example, FIG.
0.0 in sampling the current value every 0.1 second
When a transient current of 10 A flows for 5 seconds and thereafter no current flows for 0.05 seconds, the charge amount is 0.5 coulomb. On the other hand, when a current of 5 A flows for 0.1 second, the same applies to 0.5 coulomb. Then, in sampling every 0.1 second, the number of pulses generated by these C / F converters corresponds to a charge amount of 0.5 coulomb, and all have substantially the same value. That is, the number of pulses generated by the C / F converter corresponds to the number of times the integration of the integration capacitor C is completed. Since the number of pulses corresponding to the number of times of completion of the integration appears as the count value of the counter, the number of pulses corresponds to the number of times × the integrated charge amount. That is, each pulse number of 0.1 second represents the total charge amount for 0.1 second. Therefore, even if the current transiently increases, the number of integration completions corresponding thereto increases, so that the current value corresponding to the charge amount of the battery including the transient current can be calculated. As a result, a current value closer to the actual analog charge amount can be obtained in the form of a digital value than when a detected value sampled at that time is converted to a digital value as in a normal A / D conversion. It is possible to detect a current value and calculate an integrated charge amount suitable for a battery. Therefore, the current value detection error can be reduced as compared with the error correction of the current value at that time by digital sampling, and in particular, a correction circuit is inserted to correct the integrated current value itself from a small current to a large current in an analog manner. Therefore, detection of the current value with high accuracy can be expected.

As described above, in the embodiment, the sampling interval of the current value is set to 0.1 second, but this sampling interval can be determined according to the frequency generated in the C / F converter. , 0.1 second. Further, in the embodiment, the example of the assembled battery is given, but it goes without saying that the number of the battery main body may be one. Although the embodiment describes a rechargeable battery in which a circuit including a battery body and a controller are integrated as a rechargeable battery, the present invention integrates a so-called rechargeable battery pack in which a rechargeable battery and a battery are individually separated in advance. Needless to say, the present invention can be applied to a rechargeable battery pack formed as it is.

[0026]

As described above, the C / F of the present invention is used.
In the converter, the current-to-current conversion has a characteristic of linearly correcting or approximating a linear region to a current frequency conversion characteristic having a non-linear region with respect to an increase in the input current of the Miller integrating circuit. Since a correction circuit is provided and a current for frequency conversion is input to the Miller integration circuit via the correction circuit, frequency conversion can be performed with high accuracy in a wide range of detected current values. As a result, a large dynamic range can be obtained, and a C / F converter can be realized with higher linearity. In a rechargeable battery or a rechargeable battery pack using such a C / F converter, the number of pulses corresponding to the number of times the integration of the integrating capacitor of the Miller integrator is completed appears as the count value of the counter. The current value corresponding to the charge amount of the battery including the current can be calculated. Therefore, a current value closer to the actual analog charge amount can be obtained in the form of a digital value than in a case where a detected value sampled at that time is converted to a digital value as in a normal A / D conversion. Current value detection and calculation of the integrated charge amount.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment to which a C / F converter according to the present invention is applied.

FIG. 2 is an example of a rechargeable battery incorporating the C / F converter of FIG. 1, and is a circuit diagram centered on a lithium rechargeable battery incorporated in an electronic device.

3A is a diagram illustrating an example of a sub-threshold characteristic of an n-channel MOSFET transistor as a logarithmic amplification characteristic of a C / F converter, and FIG. 3B is a characteristic of correction of a polygonal line by a polygonal line function generator; FIG.

FIGS. 4 and 4 are circuit diagrams of another embodiment to which the C / F converter of the present invention is applied.

FIG. 5 is a circuit diagram of still another embodiment to which the C / F converter of the present invention is applied.

FIG. 6 is a circuit diagram of still another embodiment to which the C / F converter of the present invention is applied.

FIG. 7 is an explanatory diagram of an integrated voltage of an integrating capacitor of the Miller integrating circuit in FIG. 6;

8A and 8B are diagrams illustrating the conversion characteristics of the C / F converter, FIG. 8A is a diagram illustrating the conversion characteristics of the C / F converter in FIG. 1, and FIG. 8B is a diagram illustrating the conversion characteristics of the C / F converter in FIG. FIG. 4 is an explanatory diagram of characteristics.

FIG. 9 is an explanatory diagram of an example of a conventional C / F converter.

[Explanation of symbols]

1, 1a, 1b, 1n: Lithium battery body (battery body), 2: controller, 3: voltage detection circuit, 4, current value detection circuit, 5, temperature detection circuit, 6, 23: MPU, 7
... Memory, 7a ... Operation mode setting / monitoring program, 7
b: integrated discharge amount calculation program, 7c: remaining amount calculation program, 7d: battery storage processing program, 7e: parameter storage area, 7f: time counter, 8: A / D conversion circuit (A / D), 9a: display device 9b: timer, 9c: battery removal detection circuit, 10: rechargeable battery, 11: bus, 12
... SM bus, 13 ... charge / discharge changeover switch circuit, 20 ... electronic device, 21 ... device body, 22 ... power supply circuit, 23 ... MP
U.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G016 CB21 CB31 CC01 CC04 CC05 CC07 CC09 CC11 CC12 CC14 CC16 CC20 CC21 CC23 CC24 CC27 CC28 CD01 CD06 CD09 CD10 CE31 CF06 2G035 AA22 AB03 AC02 AD03 AD04 AD13 AD20 AD23 AD26 AD27 AD28 AD29 AD32 AD42 AD47 AD48 AD53 AD56 AD57 AD65 5G003 BA01 EA05 5H030 AA03 AA04 AS06 FF41 FF42

Claims (7)

[Claims] A mirror integrated circuit that integrates a current input to the mirror integrated circuit and compares the integrated current with a reference voltage of the voltage comparator; and outputs an output pulse from the voltage comparator. The current / frequency converter generates and resets the charge of the integration capacitor of the Miller integration circuit in response to the output pulse, and repeats the Miller integration again. On the other hand, a current-to-current conversion correction circuit having a characteristic of linearly correcting or linearly approximating the non-linear region with respect to the current frequency conversion characteristic having the non-linear region is provided. A current / frequency converter for inputting a current for frequency conversion to a circuit. 2. The method according to claim 1, wherein the non-linear region includes a conversion region in which the charge of the integration capacitor is started without being completely discharged, or for discharging the charge of the integration capacitor. 2. The current / frequency converter according to claim 1, wherein the fixed reset period includes a conversion region affecting the conversion frequency, and the correction circuit includes a transistor having an amplification characteristic according to an exponential function. 3. The non-linear region includes a conversion region in which the charge of the integration capacitor is started without being completely discharged, or a region for discharging the charge of the integration capacitor. 2. The current / frequency converter according to claim 1, wherein the fixed reset period includes a conversion region affecting the conversion frequency, and wherein the correction circuit includes a line function generator including a diode and an operational amplifier. 4. A mirror integration circuit, a voltage comparator,
A current-to-current conversion correction circuit having a characteristic of linearly correcting or linearly correcting the non-linear region with respect to a current frequency conversion characteristic having a non-linear region with respect to an increase in the input current of the Miller integrating circuit. And a current for frequency conversion is input to the Miller integration circuit via the correction circuit, and the current input to the Miller integration circuit is integrated by the Miller integration circuit to obtain a reference voltage of the voltage comparator. A current / frequency converter that generates an output pulse from the voltage comparator and discharges and resets the charge of the integrating capacitor of the Miller integrator circuit in response to the output pulse, and repeats Miller integration again; A detection of a current value that generates a detection signal of a current value corresponding to a charge current value or a discharge current value of the battery body and is input to the correction circuit A counter for counting the output pulse of the current / frequency converter; reading the value of the counter at a predetermined cycle; and charging the charge current value, the discharge current value, and charging the rechargeable battery body based on the value of the counter. A control circuit for calculating at least one of a charge amount and a discharge charge amount of the charge battery main body. 5. A Miller integrating circuit, a voltage comparator,
A current-to-current conversion correction circuit having a characteristic of linearly correcting or linearly correcting the non-linear region with respect to a current frequency conversion characteristic having a non-linear region with respect to an increase in the input current of the Miller integrating circuit. And a current for frequency conversion is input to the Miller integration circuit via the correction circuit, and the current input to the Miller integration circuit is integrated by the Miller integration circuit to obtain a reference voltage of the voltage comparator. A current / frequency converter that generates an output pulse from the voltage comparator and discharges and resets the charge of the integrating capacitor of the Miller integrator circuit in response to the output pulse, and repeats Miller integration again; A current value detection circuit that generates a detection signal of a current value corresponding to a charge current value or a discharge current value of a battery and inputs the signal to the correction circuit A counter for counting the output pulse of the current / frequency converter; reading a value of the counter at a predetermined cycle; and calculating a charge current value, a discharge current value, and a charge amount of the rechargeable battery from the value of the counter. And a control circuit for calculating at least one of the discharge charge amounts of the rechargeable battery. 6. A rechargeable battery pack connected to a main body of an electronic device via a bus and incorporated in the electronic device, comprising: a Miller integrating circuit, a voltage comparator, and a non-linear region for increasing the input current of the Miller integrating circuit. And a correction circuit for current value-to-current value conversion having a characteristic of linearly correcting or linearly correcting the nonlinearity with respect to the current frequency conversion characteristic having a current frequency conversion characteristic. A current for conversion is input, the current input to the Miller integrator is integrated by the Miller integrator and compared with a reference voltage of a comparator to generate an output pulse from the voltage comparator. A current / frequency converter that discharges and resets the charge of the integrating capacitor of the Miller integrating circuit, and repeats the Miller integration again A current value detection circuit that generates a detection signal of a current value corresponding to a charge current value or a discharge current value of a rechargeable battery and inputs the detection signal to the correction circuit; and a counter that counts the output pulse of the current / frequency converter. The value of the counter is read at a predetermined cycle, and at least one of the charge current value, the discharge current value, the integrated charge amount of the rechargeable battery, and the integrated discharge amount of the rechargeable battery is read from the value of the counter. And a control circuit for transmitting the calculated value to the electronic device main body via the bus. 7. The control circuit further includes a processor and a memory, wherein the bus is a smart battery standard bus, and wherein the processor determines a discharge current value of the rechargeable battery or the integrated discharge charge amount. 7. The rechargeable battery pack according to claim 6, comprising an internal circuit for calculating.