JP2015033236A - Electronic apparatus and electronic apparatus system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus and an electronic apparatus system in which a temperature during charging of a secondary battery is accurately grasped while considering a voltage error and the safety of the secondary battery is secured.SOLUTION: An electronic apparatus system includes an electronic apparatus 10 and a battery charger 40, and the electronic apparatus 10 includes a body part 20 and a secondary battery 30. The body part 20 includes a temperature calculation part 23, a bias voltage source 24, an electric circuit 26, a signal connection line 27, a charge connection part Q, and a signal connection part T. The secondary battery 30 includes a battery cell 32, a thermistor 34, the electric circuit 26, the signal connection line 27, a charge connection part Q, and a signal connection part T. The temperature calculation part 23 calculates a correction voltage value Vfrom an observation voltage value Vincluding an error voltage value Vsent from the signal connection line 27 on the basis of an acquired bias voltage value V, a fixed resistance value R, a partial resistance value R, and a secondary battery charging current value I-I, so that a peripheral temperature of the battery cell 32 is accurately grasped.

Description

  The present invention relates to an electronic device and an electronic device system that measure the temperature of a secondary battery during charging to ensure the safety of the secondary battery.

  Technology for charging control by measuring the temperature of the secondary battery and detecting the abnormal state in order to protect the secondary battery from abnormal heat generation due to charging when rapidly charging the secondary battery of electronic equipment Has been proposed (see, for example, Patent Document 1).

  Patent Document 1 discloses a stage of a thermal cutoff temperature based on a temperature of a secondary battery measured by a thermistor with respect to rapid charging of a secondary battery by providing a constant current stabilizing circuit, a constant voltage stabilizing circuit, a control unit, and the like in the charger. It is provided to reduce the risk of battery heat generation.

JP-A-8-308139

  In recent years, as the performance of electronic devices has improved, the capacity of secondary batteries has also increased, and secondary batteries have been charged with a large charge current. However, when a large charge current flows, the voltage generated by resistance × current = voltage is large. Become. As a result, there is a possibility that a voltage error is included in the voltage acquired from the thermistor and the temperature near the battery cell cannot be accurately grasped. However, the conventional technology (for example, Patent Document 1) does not disclose a technology considering such a voltage error.

  The present invention has been made in view of the above reasons, and its purpose is to accurately grasp the temperature at the time of charging the secondary battery in consideration of the voltage error, and to ensure the safety of the secondary battery. And providing an electronic device system.

  An electronic device of the present invention is an electronic device including a secondary battery that can be charged by a charger, and is connected to a main body having a predetermined load, and the main body via an electric circuit, and functions as the secondary battery. Battery cell, a thermistor connected to a predetermined connection point in the electric circuit and having a variable resistance value that changes in accordance with a change in ambient temperature, and an observed voltage value that changes in accordance with the variable resistance value indicated by the thermistor A temperature calculation unit that calculates an ambient temperature based on, a partial resistance value exists in at least a part of the electric circuit existing between the connection point and the main body unit, the temperature calculation unit, The temperature is calculated based on the error voltage value generated from the product of the current flowing through at least a part of the electric circuit and the partial resistance value, and the observed voltage value.

  As one aspect of the electronic apparatus of the present invention, for example, the thermistor is provided in the secondary battery including the battery cell, the temperature calculation unit is provided in the main body, and the thermistor and the temperature calculation unit are The observation voltage value is connected by a signal connection line that transmits the observed voltage value from the thermistor to the temperature calculator in the form of an analog signal.

  As one aspect of the electronic apparatus of the present invention, for example, a bias voltage source for applying a predetermined bias voltage value is connected to the signal connection line via a fixed resistor having a predetermined fixed resistance value, and the observed voltage value is A value determined from the error voltage value, the bias voltage value, the fixed resistance value, and the variable resistance value, and the temperature calculation unit calculates the variable resistance value from the observed voltage value. The corrected voltage value is calculated from the calculated variable resistance value, the bias voltage value, and the fixed resistance value, and the temperature is calculated from the corrected voltage value.

  As one aspect of the electronic apparatus of the present invention, for example, a bias voltage source for applying a predetermined bias voltage value is connected to the signal connection line via a fixed resistor having a predetermined fixed resistance value, and the observed voltage value is , A value determined from the error voltage value, the bias voltage value, the fixed resistance value, and the variable resistance value, and the temperature calculation unit includes a current flowing through at least a part of the electric circuit, and the part A corrected voltage value is calculated from the resistance value, the observed voltage value, and the bias voltage value, and a temperature is calculated from the corrected voltage value.

  As one aspect of the electronic apparatus of the present invention, for example, the connection point exists on the electric circuit connected to the negative electrode of the battery cell.

  The electronic device system of the present invention includes an electronic device and a charger.

  According to the electronic device and the electronic device system of the present invention, the temperature around the battery cell is determined from the error voltage value and the observed voltage value based on the partial resistance value generated in the electric circuit in which a large charging current accompanying rapid charging flows. It is possible to calculate. Therefore, by monitoring the temperature around the secondary battery, the abnormal temperature of the secondary battery can be detected accurately at an early stage, and the safety of the secondary battery during charging can be ensured.

1 is a block diagram showing an example of a first embodiment of an electronic device and an electronic device system according to the present invention. The block diagram which shows an example of 2nd Embodiment of the electronic device and electronic device system which concern on this invention.

  Hereinafter, preferred embodiments of an electronic device and an electronic device system according to the present invention will be described in detail with reference to FIGS. 1 and 2.

  FIG. 1 is a block diagram showing an example of a first embodiment of an electronic device and an electronic device system according to the present invention.

  The electronic device system includes an electronic device 10 and a charger 40, and the electronic device 10 includes a main body 20 and a secondary battery 30 that is built in the electronic device 10 and is detachable from the main body 20.

  The electronic device 10 is a mobile device that is operated by the secondary battery 30, such as a mobile phone such as a smartphone, a mobile terminal such as a tablet, a digital camera, a portable personal computer, and a wireless device. The main body unit 20 includes a shunt resistor 21, a current detection unit 22, a temperature calculation unit 23, a bias voltage source 24, a load 25, a charging connection unit Q, and an electric circuit 26 that electrically connects them. . Further, the main body 20 includes a signal connection line 27 that is connected to a signal connection unit T for receiving a signal from the secondary battery 30.

Shunt resistor 21 is a resistor for detecting a current flowing through the path 26, are disposed on the path 26 has a value R ₁ of the shunt resistor (implementation). The current detector 22 is arranged in parallel with the shunt resistor 21 and detects the value of the secondary battery charging current to the secondary battery 30 flowing in the electric circuit 26. The temperature calculation unit 23 includes a microprocessor (CPU) and the like, receives voltage information sent from the current detection unit 22 and the secondary battery 30, and calculates the temperature of the secondary battery 30. The bias voltage source 24 supplies a predetermined bias voltage value V ₀ . V ₀ is divided by the fixed resistance value R ₀ to generate V _TH described later.

The load 25 is a predetermined load that is generated when various circuits and the like are mounted in addition to the above-described configuration in order to control the main body unit 20 and the secondary battery 30 operates during charging. As an example, the load 25 is described as being branched from the electric circuit 26 and connected. Then, the value of the load current flowing through the load 25 and I _L, the load value of the secondary battery charging current detected by a current flowing through the path 26 by the current detection unit 22 from the I _{CGH -I} L _(charge current current The value obtained by subtracting.

  The secondary battery 30 is also a battery pack and is charged by power supplied from an external charger 40 or the like, and operates various configurations provided in the main body unit 20 by the charged power. Further, the secondary battery 30 includes a PTC (Positive Temperature Coefficient) 31 having a positive resistance temperature characteristic for monitoring the temperature in the secondary battery 30, a battery cell 32, a protection circuit (protection FET) 33, and a thermistor 34. And. The secondary battery 30 includes an electric circuit 26 that electrically connects the respective components, a charging connection portion Q, a signal connection portion T, and a signal connection line 27, similarly to the main body portion 20.

  The battery cell 32 includes a battery pack such as a lithium ion secondary battery or a nickel hydride secondary battery, and functions as the secondary battery 30 and is electrically connected to the main body 20 via the electric circuit 26.

The thermistor 34 has a variable resistance value R _TH that changes in response to a temperature change around the secondary battery 30, particularly the battery cell 32, and is electrically connected at a predetermined connection point 35 of the electric circuit 26. The change in the variable resistance value _RT of the thermistor 34 is measured as the observed voltage value V _TH1 via the signal connection T of the secondary battery 30 connected to the signal connection line 27 and the signal connection T of the main body 20. The signal is transmitted to the calculation unit 23 in the form of an analog signal. Further, there is a partial resistance value R _CN between the charging connection portion Q of the secondary battery 30 connected on the negative-side electric circuit 26 and the charging connection portion Q of the main body portion 20, and the temperature calculation unit 23 is detecting an error voltage _{V e} generated from the product of the values _I CGH -I _L and partial resistance value _{R CN} follows the battery charging current.

  The charger 40 controls a rectifier 41 that is an AC / DC converter, a power output unit 42 that outputs power to the electronic device 10 based on the power converted by the rectifier 41, and output and stop of the power output unit 42. Output control unit 43. The electronic device 10 and the charger 40 are electrically connected by a charging cable made of, for example, a USB.

  FIG. 2 is a block diagram showing an example of the second embodiment of the electronic device and the electronic device system according to the present invention.

  The difference between the second embodiment and the first embodiment is that the power output unit 42 and the output control unit 43 described above are provided in the main body unit 20. In the second embodiment, the charger 40 is a simple AC / DC converter and a simple AC adapter. If the temperature of the secondary battery 30 detected by the temperature calculation unit 23 is abnormal, the output control unit 43 is notified and the supply of charging power is stopped as in the first embodiment.

The temperature in the vicinity of the battery cell 32 is calculated based on the voltage value acquired by the temperature calculation unit 23. The observed voltage value _VTH1 transmitted from the thermistor 34 includes a voltage error. That is, the charging current value I _CHG during fast charge is very large (e.g., 4A) for, - affects error voltage V _e produced by the partial resistance value R _CN in path 26 side is grasped exact temperature It will not be possible. In the present invention, the ambient temperature of the battery cell 32 can be accurately grasped by calculating the corrected voltage value V _TH2 to be obtained by the following equation. Further, the temperature calculation section 23, the bias voltage _{V 0} and the fixed resistance _{R 0} of the pre-bias voltage source 24, partial resistance value _{R CN} and secondary battery charging current _I CHG -I _L is obtained, stored Yes.

The temperature is calculated based on the voltage value received by the temperature calculation unit 23. What is desired is a corrected voltage value V _TH2 that is a true value. The corrected voltage value V _TH2 is a value obtained by multiplying the bias voltage value V ₀ of the bias voltage source 24 by the ratio of the variable resistance value R _TH of the thermistor 34 and the fixed resistance value R ₀ of the bias voltage source 24. It can be represented by (1).

However, since the charging current value I _CHG is very large (for example, 4 A), a voltage error occurs. Error voltage V _e by the voltage error - a value obtained by multiplying the secondary battery charging current I _CHG -I _L in partial resistance value R _CN on the side of the path 26, is expressed by the following formula (2) it can.

The observed voltage value V _TH1 of the actually measured voltage is a value including the error voltage value V _e and can be expressed by the following equation (3).

From the above formula, the temperature calculation unit 23 calculates the corrected voltage value V _TH2 necessary for calculating the temperature. As an example of the calculation method, two calculation examples will be described below.

In the first calculation method, the variable resistance value R _TH is calculated from the observed voltage value V _TH1 , and the corrected voltage value V is calculated from the calculated variable resistance value R _TH , bias voltage value V ₀ , and fixed resistance value R _{0. This} is a method of calculating _TH2 .

Since the variable resistance R _TH of the aforementioned formula (1) is not known, obtaining the variable resistance R _TH by developing equation (3) by the following procedure.

As a result of the above development, the following equation (4) can be obtained.

Error voltage V _e at the equation (4) can be calculated from the equation (2), other values Motomari variable resistance R _TH because all is detected, or the value stored in the temperature calculation section 23, the formula ( By substituting into 1), the following equation (5) for obtaining the corrected voltage value V _TH2 is obtained.

The second calculation method includes the secondary battery charging current _I CHG -I _L flowing path 26, a partial resistance value _{R CN,} and the observed voltage value _{V TH1,} the correction voltage value _{V TH2} from the bias voltage _{V 0} Metropolitan It is a method of calculation.

The expression (3) is summarized into the following expression (6) in terms of the error voltage value V _e and the bias voltage value V ₀ .

From the expressions (1) and (6), the observed voltage value V _TH1 is expressed by the following expression (7).

When the corrected voltage value V _TH2 is obtained from the equation (7), the following equation (8) can be obtained.

Since R _TH / (R _TH + R ₀ ) term in the formula (8) is R _TH / (R _TH + R ₀ ) = V _TH2 / V ₀ from the formula (1), the formula (8) is as follows: Can be deployed.

As a result of expansion of the equation (8), the following equation (9) is obtained.

Substituting equation (2) for V _{e in} equation (9) above, the following equation (10) can be obtained.

Since each value of Expression (10) is a value detected or stored by the temperature calculation unit 23, the corrected voltage value V _TH2 is obtained. Naturally, the equation (10) obtained by the second calculation method is the same as the equation (5) obtained by the first calculation method.

By the above calculation, the corrected voltage value V _TH2 can be calculated. In particular, the temperature in the vicinity of the battery cell 32 can be accurately measured, and the abnormal temperature at the time of charging the secondary battery 30 can be detected at an early stage. 30 safety can be guaranteed. In addition, although the two calculation examples were demonstrated, it is not limited to this.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  The electronic device and the electronic device system according to the present invention are capable of accurately measuring the temperature of a secondary battery of an electronic device such as a mobile phone such as a smartphone, a mobile terminal such as a tablet, a digital camera, a portable personal computer, or a measuring instrument. It is applicable to.

DESCRIPTION OF SYMBOLS 10: Electronic device 20: Main-body part 21: Shunt resistance 22: Current detection part 23: Temperature calculation part 24: Bias voltage source 25: Load 26: Electric circuit 27: Signal connection line 30: Secondary battery 32: Battery cell 34: Thermistor 35: connection point 40: charger Q: charging connection section T: signal connections I _CHG: charge current I _CHG -I _L: battery charging current R _0: the fixed resistance value R _CN: partial resistance value R _TH: variable Resistance value V ₀ : Bias voltage value V _e : Error voltage value

Claims (6)

An electronic device including a secondary battery that can be charged by a charger,
A main body having a predetermined load;
A battery cell connected to the main body via an electric circuit and functioning as the secondary battery;
A thermistor connected to a predetermined connection point in the electric circuit and having a variable resistance value that changes in response to a change in ambient temperature;
A temperature calculation unit that calculates an ambient temperature based on an observed voltage value that varies in accordance with a variable resistance value indicated by the thermistor,
There is a partial resistance value in at least a part of the electric circuit existing between the connection point and the main body,
The electronic device, wherein the temperature calculation unit calculates a temperature based on an error voltage value generated from a product of a current flowing through at least a part of the electric circuit and the partial resistance value, and the observed voltage value. The electronic device according to claim 1,
The thermistor is provided in the secondary battery including the battery cell;
The temperature calculation unit is provided in the main body,
The electronic device in which the thermistor and the temperature calculation unit are connected by a signal connection line that transmits the observed voltage value from the thermistor to the temperature calculation unit in the form of an analog signal. The electronic device according to claim 2,
A bias voltage source for applying a predetermined bias voltage value is connected to the signal connection line through a fixed resistor having a predetermined fixed resistance value,
The observed voltage value is a value determined from the error voltage value, the bias voltage value, the fixed resistance value, and the variable resistance value;
The temperature calculation unit calculates the variable resistance value from the observed voltage value, calculates a corrected voltage value from the calculated variable resistance value, the bias voltage value, and the fixed resistance value, and the corrected voltage value Electronic device that calculates temperature from The electronic device according to claim 2,
A bias voltage source for applying a predetermined bias voltage value is connected to the signal connection line through a fixed resistor having a predetermined fixed resistance value,
The observed voltage value is a value determined from the error voltage value, the bias voltage value, the fixed resistance value, and the variable resistance value;
The temperature calculation unit calculates a corrected voltage value from a current flowing through at least a part of the electric circuit, the partial resistance value, the observed voltage value, and the bias voltage value, and calculates a temperature from the corrected voltage value. ,Electronics. The electronic device according to any one of claims 1 to 4,
The electronic device in which the connection point exists on the electric circuit connected to the negative electrode of the battery cell.   The electronic device system containing the electronic device of any one of Claim 1 to 5, and a charger.

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