JP2013236475A - Electronic apparatus device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus device that can increase a lifetime of a battery used as a driving source for an electronic apparatus device body and highly accurately estimate a lifetime of the battery with a low-cost and simple method.SOLUTION: An electronic apparatus device includes: a capacitor storing driving energy for an electronic apparatus device body and supplying power to the electronic apparatus device body; a battery connected to the capacitor via a normally-opened (normally-OFF) type switch, for charging the capacitor when the switch is closed (ON); a power supply control unit controlling charging of the capacitor so that a terminal voltage of the capacitor is detected, and when the terminal voltage is reduced to a preset discharge management voltage, the switch is closed, and when a preset charging time has passed, the switch is opened; and battery lifetime estimating means for estimating a lifetime of the battery on the basis of the terminal voltage of the capacitor at a time point when a predetermined time has passed from the start of charging of the capacitor.

Description

  The present invention relates to an electronic device apparatus capable of prolonging the life of a battery used as a drive source of an electronic device main body and easily estimating the life of the battery.

  Node sensors (electronic devices) that are installed at various observation points and measure physical quantities such as temperature, pressure, and vibration generally use batteries as drive sources and communicate information wirelessly with an information center. (Refer patent document 1). Further, in this type of node sensor, for example, an intermittent operation is performed in order to suppress the power consumption of the battery and to reduce the maintenance cost for the battery.

  By the way, when the remaining battery level (battery capacity) is reduced, it is possible to determine the lifetime of the battery incorporated in the electronic device (sensor node) described above by paying attention to the battery characteristic that the terminal voltage of the battery rapidly decreases. Has been done. In addition, as a method for estimating the battery life with high accuracy, for example, the terminal voltage of the battery is determined in consideration of the power dependency of the battery and the environmental temperature, or the same characteristics (same specifications) as the battery incorporated in the electronic device apparatus It has been proposed to prepare a battery, connect the battery to a pseudo load, pass a current, and monitor the terminal voltage of the battery to estimate the battery life (see, for example, Patent Document 2).

JP 2011-55186 A JP 2011-145986 A

  However, the battery life estimation method introduced in Patent Document 2 requires means for measuring the battery voltage and the load current, respectively. Moreover, generally, high-precision hardware (such as an AD converter) is required to increase the measurement accuracy of a weak load current. Further, as described above, when the battery life is estimated using the pseudo load, it cannot be denied that the hardware configuration becomes large.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electronic device that can extend the life of a battery used as a drive source of the electronic device main body.

  Another object of the present invention is to provide an electronic device apparatus having a battery life estimation function that can accurately estimate the battery life by a low-cost and simple method.

  In order to achieve the above-described object, the electronic device apparatus according to the present invention includes, for example, an electronic device body such as a sensor node intermittently operated at a predetermined cycle, and stores the drive energy of the electronic device body to A capacitor such as an electric double layer capacitor to be supplied, a battery that is connected to the capacitor via a normally open switch and charges the capacitor when the switch is closed (on); and And a power supply control unit that controls the opening and closing of the switch to control the charging of the capacitor by detecting a terminal voltage.

  Preferably, the power supply control unit closes (turns on) the switch to charge the capacitor when the terminal voltage of the capacitor drops to a preset discharge management voltage, and charges the capacitor when the capacitor is charged. When the voltage reaches a preset charge management voltage or when a preset charge time has elapsed, the switch is opened (turned off) to stop charging the capacitor.

  The electronic device according to the present invention further includes battery life estimation means for estimating the battery life from the terminal voltage of the capacitor when a predetermined time has elapsed from the start of charging of the capacitor. .

  Preferably, charging of the capacitor is performed via a resistor, and the battery life estimation means responds to a charging time constant of the capacitor determined by a capacity of the capacitor and a resistance value of the resistor from the start of charging of the capacitor. The battery life is estimated by comparing the terminal voltage of the capacitor measured at the time when the determined time elapses with a preset voltage threshold.

  According to the electronic device apparatus having the above configuration, the charging energy stored in the capacitor is used as a drive energy source of the electronic device body, and when the charging energy of the capacitor is reduced, the capacitor is connected to the capacitor via a normally open switch. Since the capacitor is charged by the connected battery, the battery is not used continuously. Therefore, the battery performance can be recovered by giving the battery a rest period and utilizing the chemical self-recovery action of the battery during the rest period, thereby reducing the deterioration of the battery performance due to continuous use and extending the battery life. be able to.

  In addition, since the life of the battery that charges the capacitor is estimated by paying attention to the change in the terminal voltage of the capacitor during charging, the battery life estimation method itself is simple and the battery life can be reduced using low-cost hardware. It can be estimated with high accuracy. Therefore, it is possible to easily and accurately manage the battery life and grasp the replacement time of the battery.

The figure which shows the whole structure of the electronic device apparatus which concerns on one Embodiment of this invention. FIG. 2 is a diagram showing a schematic configuration of a power supply control unit in the electronic device apparatus shown in FIG. 1. FIG. 3 is an operation waveform diagram for explaining an operation of the electronic device apparatus shown in FIG. 1. The figure which shows the procedure of the charge control of the capacitor | condenser in the electronic device apparatus shown in FIG. 1, and the determination process of battery life. The figure which shows the charge characteristic of the capacitor | condenser depending on battery performance (battery capacity).

Hereinafter, an electronic device according to an embodiment of the present invention will be described with reference to the drawings.
The electronic device 1 is installed in various environments, for example, in areas and places that are unattended on a daily basis, as shown in FIG. 1, for example, and operates with a battery as a driving source. It consists of sensor nodes that collect state information of the target. This sensor node (electronic device apparatus) 1 plays a role of notifying the management center (not shown) of the monitoring data such as the weather information and the status information of the monitoring target by wireless communication.

  The sensor node 1 incorporates a battery 11 and operates using power obtained by converting the output voltage of the battery 11 via a DC / DC converter 12 as a drive source. In FIG. 1, reference numeral 13 denotes a wireless circuit that wirelessly communicates with the management center, and reference numeral 14 denotes a control unit that forms a main part of the electronic device 1. The battery 11 basically serves as a drive energy source for supplying power (power energy) to the electronic device main body 10 including the wireless circuit 13 and the control unit 14 to operate the electronic device main body 10.

  Here, the control unit 14 forming a part of the electronic device main body 10 includes a wireless communication unit 15, a communication control unit 16, and a power supply control unit 17 described later, which are realized as software functions incorporated in a microprocessor, for example. And an internal power supply unit 18 for supplying power to the microprocessor. The control unit 14 detects (monitors), for example, temperature, humidity, and other information using various sensors 19 under the control and management of the communication control unit 16, and transmits the detected (monitored) data to the communication. It plays a role of notifying the management center from the control unit 16 via the wireless circuit 13.

  The sensor node 1 basically configured as described above is characterized in that the present invention is characterized by an electronic device body 10 including the wireless circuit 13 and the control unit 14, the battery 11, and the DC / DC converter 12. The power source unit 20 is interposed between the battery unit and the battery 11, and driving energy is supplied from the power source unit 20 to the electronic device main body 10 instead of the battery 11. In other words, a power source unit 20 that replaces the battery 11 is provided as a drive energy source for the electronic device main body 10.

  The power supply unit 20 includes a normally open type switch 21, a resistor 22 connected in series to the switch 21, and a capacitor 23 connected to the switch 21 via the resistor 22. . The capacitor 23 is made of a large-capacity capacitor such as an electric double layer capacitor, and is connected to the output terminal of the DC / DC converter 12 on the battery side through the switch 21 and the resistor 22 in series. It is connected to the power supply terminal of the electronic device body 10. The normally open switch 21 may be an electromagnetic relay, but may be a semiconductor switching element such as a MOS-FET or IGBT.

  The capacitor 23 is normally disconnected from the DC / DC converter 12 on the battery side by the switch 21, but is connected to the battery side when the switch 21 is closed (ON) and is connected to the DC / DC. The battery is charged by receiving the output voltage from the converter 12. The power energy charged in the capacitor 23 is supplied as drive energy to the electronic device main body 10 including the wireless circuit 13 and the control unit 14 described above.

  In other words, the electronic device main body 10 is disconnected from the DC / DC converter 12 by the power supply unit 20, and the output of the battery 11 obtained via the DC / DC converter 12 is used as a direct drive energy source. Instead of using as a drive, the power energy stored in the capacitor 23 of the power supply unit 20 charged by receiving the output of the battery 11 (output of the DC / DC converter 12) is obtained from the power supply unit 20 It is positioned to operate using energy.

  By the way, the power supply unit 20 composed of the switch 21, the resistor 22, and the capacitor 23 receives the control of the power supply control unit 17 to drive the switch 21 to be closed (ON) and to drive the switch 21 via the resistor 22. The capacitor 23 is charged to store the power energy from the battery 11. For example, as shown in FIG. 2, the power supply controller 17 includes an AD converter 24 that detects a terminal voltage (charge / discharge voltage) Vc of the capacitor 23 and a switch drive that drives the switch 21 to be closed (ON). A circuit 25 and a control program 26 for operating the switch drive circuit 25 according to the terminal voltage Vc of the capacitor 23 detected through the AD converter 24 are provided.

  This control program 26 is set in the above-described microprocessor, and basically closes (turns on; conducts) the switch 21 in accordance with the terminal voltage Vc of the capacitor 23. Specifically, the control program 26 closes and drives the switch 21 to charge the capacitor 23 when the terminal voltage Vc of the capacitor 23 drops to a preset discharge management voltage Vo. When the terminal voltage Vc reaches a preset charge management voltage Vh during charging, the switch 21 is opened (closed drive is released) and charging of the capacitor 23 is stopped. Note that when the preset charging time Ton has elapsed, the switch 21 may be opened to stop the charging of the capacitor 23.

  By the switch 21 controlled in this way, the electronic device main body 10 is regularly disconnected from the DC / DC converter 12 by the power supply unit 20 as described above. The DC / DC converter 12 is connected to the power supply unit 20 only when the capacitor 23 is charged. Therefore, the battery 11 is kept in a rest state except for a period during which the capacitor 23 is charged, and is released from its continuous use.

  Furthermore, the control program 26 includes a battery life determination function (battery life estimation means) for determining the life of the battery 11 from the terminal voltage Vc of the capacitor 23 when the capacitor 23 is charged. This battery life determination function determines whether the performance of the battery 11 has deteriorated and the battery life has been reached from the terminal voltage Vc of the capacitor 23 when a predetermined time has elapsed since the start of charging of the capacitor 23. judge.

  Specifically, the battery life determination function compares the terminal voltage Vc1 of the capacitor 23 when a preset time T1 has elapsed from the start of charging of the capacitor 23 with a preset voltage threshold Vth. Estimate life. The elapsed time T1 from the start of charging is set as a time corresponding to a charging time constant τ (= R · C) of the capacitor 23 determined by, for example, the capacitance C of the capacitor 23 and the resistance value R of the resistor 22. Is done. When it is estimated that the life of the battery 11 is exhausted by this battery life determination function, or when it is estimated that the remaining life period of the battery 11 is short, an alarm is issued and the battery life information is displayed. The management center is notified.

  Here, the operation of the power supply unit 20 under the control of the power supply control unit 17 and the change in the terminal voltage Vc of the capacitor 23 accompanying the closing operation of the switch 21 of the power supply unit 20 will be described with reference to FIG. I will explain.

  The electronic device main body 10 including the wireless circuit 13 and the control unit 14 is intermittently operated for a predetermined time Tc every predetermined cycle Ts, for example, and operates by obtaining power energy from the capacitor 23. The period Ts differs depending on the monitoring target of the sensor node 1, but is set as 1 hour, for example, and the intermittent operation time Tc is set as 1 minute, for example. Therefore, the power consumption (current consumption) at the sensor node 1 is the drive power (current consumption It) required for the operation only during the short-term (one minute) intermittent operation of the electronic device body 10 as shown in FIG. Thus, the rest period is only the weak standby power (standby current Is) of the electronic device body 10.

  The power consumption (current consumption) in the electronic device main body 10 is covered by the power energy accumulated (charged) in the capacitor 23 as described above. Accordingly, the terminal voltage Vc of the capacitor 23 decreases by a predetermined amount every the intermittent operation time Tc as shown in FIG. The control program 26 in the power supply control unit 17 monitors (detects) the terminal voltage Vc of the capacitor 23 that changes as described above with the intermittent operation of the electronic device body 10 and closes the switch 21 (ON). ) Drive to charge the capacitor 23 and determine the life of the battery 11.

  FIG. 4 shows the procedure of the charging control of the capacitor 23 and the battery life determination process in the control program 26 in the power supply control unit 17. The determination process will be described. When the electronic apparatus body 10 is intermittently operated, first, the terminal voltage Vc of the capacitor 23 is detected via the AD converter 24 <step S1>. Then, it is determined whether or not the terminal voltage Vc has decreased to the above-described discharge management voltage Vo (Vc ≦ Vo) <step S2>.

  When it is confirmed that the terminal voltage Vc has not decreased to the discharge management voltage Vo by this determination process, sufficient electric energy for driving the electronic device main body 10 is left in the capacitor 23. Therefore, the switch 21 is not closed (ON; conduction), and the capacitor 23 is not charged. By such a processing routine for closing control of the switch 21, the battery 11 is constantly disconnected from the electronic device main body 10 and put into a resting state regardless of the intermittent operation of the electronic device main body 10 described above. .

  On the other hand, when the terminal voltage Vc decreases to the discharge management voltage Vo during the intermittent operation of the electronic device body 10, the switch drive circuit 25 is driven under the control of the control program 26, and the switch 21 is turned on. It is closed (ON; conducting), and charging of the capacitor 23 is started <step S3>. The capacitor 23 is continuously charged until, for example, the terminal voltage Vc reaches the charge management voltage Vh, or until a preset charge required time Ton of the capacitor 23 elapses.

  When the charging of the capacitor 23 executed in this way is started, the control program 26 activates a timer (not shown) <Step S4> and sets the charging time of the capacitor 23 (elapsed time from the start of charging). Monitor <Step S5>. Then, the terminal voltage Vc1 of the capacitor 23 is detected when a predetermined time set in advance (elapsed time T1), and the terminal voltage Vc1 after the elapse of the predetermined time T1 is stored in the internal memory 27 <Step S6>. .

  Thereafter, it is determined whether or not the elapsed time from the start of charging has reached the required charging time Ton of the capacitor 23 <Step S7>. When the required charging time Ton is reached, the capacitor 23 is sufficiently charged. It is determined that the switch 21 is closed (ON; conduction) by the switch drive circuit 25 (step S8). As a result, the normally open switch 21 returns to the open state, and the charging of the capacitor 23 is completed accordingly.

  Thereafter, the control program 26 stores the terminal voltage Vc1 of the capacitor 23 and the preset voltage threshold value Vth when a predetermined time has elapsed from the start of charging stored in the internal memory 27 as described above (elapsed time T1). <Step S9>, when the terminal voltage Vc1 is less than the voltage threshold Vth (Vc1 <Vth), it is determined that the characteristic of the battery 11 has deteriorated, that is, the battery life is reached, and an alarm (alarm) ) <Step S10>. When the terminal voltage Vc1 of the capacitor 23 exceeds the voltage threshold value Vth, it is determined that the battery 11 has no performance deterioration, that is, the remaining capacity of the battery 11 has a sufficient margin. Return to routine.

  By the way, the terminal voltage (charge voltage) Vc1, Vc2 of the capacitor 23 after a predetermined time (T1, T2) has elapsed from the start of charging of the capacitor 23 depends on the remaining capacity (battery performance) of the battery 11, and It decreases as the remaining capacity (battery performance) decreases (deteriorates). FIG. 5 shows changes in the terminal voltage (relative value) Vc1 of the capacitor 23 when the first time T1 has passed since the start of charging of the capacitor 23. Contrast with the change in the terminal voltage (relative value) Vc2 of the capacitor 23 when the second time T2 (required charging time Ton) elapses from the start of charging when the capacitor 23 is expected to be sufficiently charged. It shows.

  Specifically, the horizontal axis of FIG. 5 indicates that the charge amount (terminal voltage at the completion of charging) when the capacitor 23 is charged with a new battery 11 is 100%, and the battery performance deteriorates (remaining battery capacity decreases). The relative value of the terminal voltage at the completion of charging of the capacitor 23 that varies with the change is shown. Further, the vertical axis of FIG. 5 shows the change in the terminal voltage (relative value) of the capacitor 23 after a predetermined time has elapsed since the charging start, assuming that the terminal voltage when the capacitor 23 is completely charged by the new battery 11 is 100%. Shows the percentage. In FIG. 5, the characteristic A is the change rate (ratio) of the terminal voltage V1 (relative value) after the first time (T1 = τ) has elapsed from the start of charging, and the characteristic B is the second change from the start of charging. The ratio (ratio) of change in the terminal voltage V2 (relative value) after elapse of time (Tc2 = 3τ) is shown.

  As shown in FIG. 5, the change rate of the terminal voltage Vc1 of the capacitor 23 depending on the battery characteristics after the elapse of the first time (T1 = τ) shortly after the start of charging is expressed as follows. Is more remarkable than the rate of change of the terminal voltage Vc2 of the capacitor 23 depending on the battery characteristics after the second time (T2 = 3τ) has elapsed since the start of charging when it can be considered that the battery has been fully charged.

  In particular, in the example shown in FIG. 5, when the charge amount of the capacitor 23 decreases from 100% to 20% due to the deterioration of the battery characteristics, the terminal of the capacitor 23 after the second time (T2 = 3τ) has elapsed. Compared with the rate of change of the voltage Vc2 being about 1% at most, it depends on the battery characteristics of the terminal voltage Vc1 of the capacitor 23 after the first time (T1 = τ) has passed since the start of charging. The rate of change is as much as 5%.

  Therefore, as described above, by paying attention to the terminal voltage (charge voltage) of the capacitor 23 after the first time (T1 = τ) has passed since the start of charging of the capacitor 23, the capacitor 23 is charged. It is possible to accurately estimate the performance deterioration of the battery 11 provided and to estimate the life of the battery 11 with high accuracy. In addition, since the rate of change depending on the battery performance of the terminal voltage Vc1 after the first time (T1 = τ) has elapsed since the start of charging is large, an inexpensive and simple AD converter 24 with a small number of bits is used. Even in such a case, the change in the terminal voltage Vc can be reliably captured.

  As described above, in the electronic apparatus device 1, the capacitor that is regularly disconnected from the battery 11 and charged by receiving the power energy from the battery 11 via the switch 21 when the charging energy decreases. The terminal voltage (charging voltage) Vc at the time of charging 23 is detected, and the performance deterioration (battery life) of the battery 11 is estimated. Therefore, according to the electronic apparatus device 1 having the battery life estimation function described above, it is not necessary to detect a weak load current flowing from the battery 11 to the electronic apparatus main body 10 including the wireless circuit 13 and the control unit 14. In addition, since a large change depending on the battery characteristics of the terminal voltage Vc of the capacitor 23 is detected when a relatively short time has elapsed since the start of charging, the battery life can be estimated with high accuracy under a simple hardware configuration. Can do.

  Further, if the information on the life of the battery 11 estimated as described above is notified to the management center using, for example, the wireless circuit 13, the electronic device apparatus 1 is transmitted to the electronic apparatus apparatus 1 at a management center remote from the electronic apparatus device 1. The performance of the built-in battery 11 can be accurately grasped. Furthermore, the management center can provide an effect that it is possible to accurately instruct the replacement of the battery 11 whose performance has deteriorated (life is exhausted). In this case, it is desirable to notify the management center of the ID information of the electronic device apparatus 1 or the information regarding the installation position of the electronic device apparatus 1 together with the life information of the battery 11.

  The present invention is not limited to the embodiment described above. For example, the terminal voltage of the capacitor 23 after the elapse of a predetermined time from the start of charging detected as described above is notified to the management center, and the life of the battery 11 incorporated in the electronic device (sensor node) 1 on the management center side is notified. It is also possible to configure the system to make the determination. In this case, the configuration of the electronic device apparatus 1 can be further simplified, or the processing load on the electronic device apparatus 1 can be reduced.

  Further, terminal voltages (Vc1, Vc2 to Vcn) at different elapsed times (T1, T2 to Tn) from the start of charging of the capacitor 23 are detected, and these terminal voltages are comprehensively determined to determine the life of the battery 11. Of course, it is also possible to determine. Further, regarding the voltage threshold value Vth that is the above-described terminal voltage determination criterion in estimating the battery life, the specifications (configuration, type, etc.) of the battery 11 and the input / output voltage specifications of the DC / DC converter 12 described above. Furthermore, it is sufficient to set in advance according to the load specifications (operation cycle, power consumption, etc.) of the electronic device main body comprising the radio circuit 13 and the control unit 14.

  Further, the timing for detecting the terminal voltage of the capacitor 23 in estimating the battery life, that is, the elapsed time from the start of charging, for example, considers not only the performance of the battery 11 but also the charging characteristics of the capacitor 23 and the like. Of course, it is possible to decide. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

1 Electronic equipment (sensor node)
DESCRIPTION OF SYMBOLS 10 Electronic device main body 11 Battery 12 DC / DC converter 13 Wireless circuit 14 Control part 15 Wireless communication part 16 Communication control part 17 Power supply control part 18 Internal power supply part 19 Sensor 20 Power supply part 21 Switch 22 Resistance 23 Capacitor 24 AD converter 25 Switch Drive circuit 26 Control program 27 Internal memory

Claims (5)

An electronic device body,
A capacitor for storing the drive energy of the electronic device body,
A battery connected to the capacitor via a normally open switch to charge the capacitor when the switch is closed;
An electronic device apparatus comprising: a power supply control unit that detects a terminal voltage of the capacitor and controls opening and closing of the switch to control charging of the capacitor. The electronic device main body is a sensor node that is intermittently operated at a predetermined cycle and operates using the charging energy of the capacitor as a drive source,
The electronic device according to claim 1, wherein the capacitor is an electric double layer capacitor.   The power control unit closes the switch to charge the capacitor when the terminal voltage of the capacitor drops to a preset discharge management voltage, and the capacitor terminal voltage is preset when the capacitor is charged. The electronic device apparatus according to claim 1, wherein when the charging management voltage is reached or when a preset charging time has elapsed, the switch is opened to stop charging the capacitor. In the electronic device device according to any one of claims 1 to 3,
The electronic apparatus apparatus further comprises battery life estimation means for estimating a life of the battery from a terminal voltage of the capacitor when a predetermined time has elapsed from the start of charging of the capacitor. The capacitor is charged through a resistor,
The battery life estimating means is a terminal of the capacitor at a time when a time determined according to a charging time constant of the capacitor determined by a capacity of the capacitor and a resistance value of the resistor has elapsed from the start of charging of the capacitor. The electronic device apparatus according to claim 4, wherein the battery life is estimated by comparing the voltage with a preset voltage threshold value.

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