Charging device, electronic device, charging method, and computer program

Abstract

To improve the time efficiency of charging a secondary battery while suppressing the deterioration of an electronic circuit.SOLUTION: A charging device 6 comprises: a charging circuit 61 charging a secondary battery 4; and a charge control unit 62 that comprises a temperature information acquisition unit acquiring temperature information indicating the temperature pertaining to the secondary battery 4 and controls the charging circuit 61 on the basis of the temperature information acquired by the temperature information acquisition unit. The charge control unit 62 allows the charging circuit 61 to start charging the secondary battery 4 when the temperature of the secondary battery 4 is lower than a first threshold temperature and a first condition is satisfied, and does not allow the charging circuit 61 to start charging the secondary battery 4 when the temperature of the secondary battery 4 is lower than the first threshold temperature and the first condition is not satisfied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charging device, an electronic device, a charging method, and a computer program. [Background technology]

[0002] In lithium-ion batteries, which are widely used as secondary batteries, when they are charged at low temperatures, lithium metal in the electrolyte precipitates, causing deterioration such as an increase in internal resistance, a rapid decrease in capacity, and deterioration in quality due to an electrical short circuit within the battery. For this reason, a lower limit charging temperature has been set below which these problems do not occur, and charging is stopped when the temperature falls below this lower limit charging temperature.

[0003] Here, the temperature of the secondary battery may fluctuate slightly but frequently around the lower limit temperature. The temperature sensor may pick up noise, causing the temperature indicated by the output signal to fluctuate around the lower limit temperature. In such cases, charging may start or resume and stop frequently, which may reduce the reliability of electronic circuits such as the switching IC (Integrated Circuit) and relays that start and stop charging.

[0004] To address this problem, Patent Document 1 discloses a technique for controlling the charging state according to the temperature of a secondary battery by setting a first threshold temperature at which charging suspension is lifted and a second threshold temperature at which the charging state is transitioned to a charging suspension state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-80406 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology disclosed in Patent Document 1, when the temperature of the secondary battery is stable between the first threshold temperature and the second threshold temperature, or when it takes time for the temperature of the secondary battery to rise from the second threshold temperature to the first threshold temperature, a state occurs in which the secondary battery is not charged even though its temperature is higher than the first threshold temperature. Thus, in the technology disclosed in Patent Document 1, the time efficiency of charging is low, the time required for charging is long, and in some cases, there is a problem of insufficient remaining capacity.

[0007] Similar problems exist, although to varying degrees, for secondary batteries other than lithium-ion batteries.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the time efficiency of charging a secondary battery while suppressing deterioration of electronic circuits. [Means for solving the problem]

[0009] In order to achieve the above object, a charging device according to a first aspect of the present invention comprises: A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit is the charging circuit permits charging of the secondary battery when a temperature related to the secondary battery is less than a first threshold temperature and a first condition related to the temperature of the secondary battery is satisfied; When the temperature related to the secondary battery is less than the first threshold temperature and the first condition is not satisfied, charging of the secondary battery is permitted. Without a charging circuit that: i) permits charging of the secondary battery when a temperature related to the secondary battery is equal to or higher than the first threshold temperature; and ii) stops charging of the secondary battery when the temperature related to the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature; The first condition is that the calculated time to reach the second threshold temperature is less than a certain time. In order to achieve the above object, a charging device according to a second aspect of the present invention comprises: A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit is the charging circuit permits charging of the secondary battery when a temperature related to the secondary battery is less than a first threshold temperature and a first condition related to the temperature of the secondary battery is satisfied; when the temperature related to the secondary battery is less than the first threshold temperature and the first condition is not satisfied, charging of the secondary battery is not permitted; a charging circuit that: i) permits charging of the secondary battery when a temperature related to the secondary battery is equal to or higher than the first threshold temperature; and ii) stops charging of the secondary battery when the temperature related to the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature; When the temperature of the secondary battery is below the second threshold temperature, a fixed time is waited, and after waiting for the fixed time, charging is allowed if any of the following conditions is met: the temperature of the secondary battery is on an increasing trend, the rate of temperature increase is higher than a certain rate of increase, the slope of the temperature change is on an increasing trend, or the calculated time to reach the second threshold temperature is shorter than a certain time. In order to achieve the above object, a charging device according to a third aspect of the present invention comprises: A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit controls the charging circuit, When the temperature of the secondary battery is equal to or higher than a first threshold temperature, charging of the secondary battery is permitted; permitting charging when the temperature of the secondary battery is less than a second threshold temperature that is lower than the first threshold temperature and a second condition regarding the temperature of the secondary battery is satisfied; When the temperature of the secondary battery is less than the second threshold temperature and does not satisfy the second condition, charging is stopped; The second condition is one of the following: the temperature of the secondary battery is on an increasing trend; the rate of temperature increase is higher than a certain rate of increase; the slope of the temperature change is on an increasing trend; and the calculated time to reach the second threshold temperature is shorter than a certain time. Effect of the Invention

[0010] According to the above configuration, it is possible to improve the time efficiency of charging the secondary battery while suppressing deterioration of the electronic circuit. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram of an electronic device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a charging control unit according to an embodiment of the present invention. [Diagram 3] 4 is a flowchart showing a charging control process according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the relationship between temperature change and charging of the rechargeable battery according to the first embodiment of the present invention. [Diagram 5] 10 is a flowchart showing a charging control process according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart showing a modified example of the charge control process according to the second embodiment of the present invention. [Figure 7]10 is a flowchart showing a charging control process according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a charging device, an electronic device, a charging method, and a computer program according to embodiments of the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals.

[0013] (Embodiment 1) The electronic device of the present embodiment is a device that includes a secondary battery, operates while consuming power stored in the secondary battery, and realizes various functions. However, the various functions and configurations of the electronic device are optional. Therefore, the following description will focus on a charging device that charges the secondary battery, which is characteristic of the embodiment.

[0014] As shown in the block diagram of FIG. 1, an electronic device 1 according to this embodiment includes an input unit 3 that receives power from an AC (Alternating Current) adapter 2, a secondary battery 4, a temperature sensor 5 that detects the temperature of the secondary battery 4, and a charging device 6. Since the method for measuring the temperature of the secondary battery 4 is arbitrary, in this embodiment, it is described as the temperature TB related to the secondary battery 4. The temperature TB related to the secondary battery 4 includes, for example, the temperature of an arbitrary part of the secondary battery 4, the temperature of the electrodes of the secondary battery 4, the temperature of the surface of the secondary battery 4, the temperature at a position within the range where the heat of the secondary battery 4 is transmitted, etc., and includes any of these temperatures measured by the temperature sensor 5.

[0015] The charging device 6 includes a charging circuit 61 that charges the secondary battery 4 when power is being supplied from the AC adapter 2 to the input unit 3, and that stabilizes and outputs the output voltage of the secondary battery 4 when power is not being supplied from the AC adapter 2, and a charging control unit 62 that controls the charging circuit 61. The charging control unit 62 includes, for example, a microcomputer.

[0016] The AC adapter 2 is an external power supply for the electronic device 1, and generates a DC power supply voltage for the electronic device 1 from an AC power supply. The AC adapter 2 includes a connection plug that is detachably connected to the input unit 3, and supplies DC power to the electronic device 1 via the connection plug connected to the input unit 3. The external power supply may be a DC power supply.

[0017] A connection plug of an AC adapter 2 is detachably attached to the input unit 3, and DC power is supplied from the AC adapter 2. The input unit 3 supplies the supplied DC power to each internal circuit (not shown) of the electronic device 1 as operating power, and further supplies the power to the charging device 6.

[0018] The secondary battery 4 is a rechargeable battery, and is, for example, a lithium ion battery.

[0019] The temperature sensor 5 includes a temperature detection element such as a thermistor or a thermocouple, and is installed at a position where the temperature TB related to the secondary battery 4 can be measured.

[0020] The charging circuit 61 of the charging device 6 includes a reverse current prevention circuit, a conductive / non-conductive switch, etc., a charging circuit that applies the DC voltage supplied from the AC adapter 2 to the secondary battery 4, and a regulator that regulates the output voltage of the secondary battery 4, and charges the secondary battery 4 when a DC voltage is being supplied from the AC adapter 2 under the control of the charging control unit 62, and stabilizes the output voltage of the secondary battery 4 and supplies it to the internal circuit when no power supply voltage is being supplied from the AC adapter 2. Also, the charging circuit 61 outputs a power supply detection signal to the charging control unit 62 when power supply voltage is being supplied from the AC adapter 2.

[0021] As shown in the block diagram of FIG. 2, the charging control unit 62 includes a processor 621, a random access memory (RAM) 622, a read only memory (ROM) 623, and an input / output interface (hereinafter, I / O) 624.

[0022] The processor 621 uses the RAM 622 as a work memory, executes a control program stored in the ROM 623, and executes a charging control process, which will be described later with reference to Fig. 3. The processor 621 also includes an internal timer.

[0023] The RAM 622 functions as a work area for the processor 621, and stores the programs being executed and various data.

[0024] The ROM 623 stores a control program for the charging control process, which will be described later, fixed data used for the control, and the like. The fixed data includes a first threshold temperature T1, a second threshold temperature T2, a reference time tr, and the like. The second threshold temperature T2 is a temperature threshold for determining whether or not charging is stopped during charging, and is basically a threshold temperature for determining that charging is stopped when the temperature TB related to the secondary battery 4 drops below the second threshold temperature T2 during charging. The second threshold temperature T2 is set to a limit temperature below which the secondary battery 4 is damaged, such as by deposition of metal ions in the electrolyte, if charging is performed at a temperature lower than the second threshold temperature T2. In the case of a lithium-ion battery, it is set to about 0°C. On the other hand, the first threshold temperature T1 is a temperature threshold for determining whether or not charging is started during non-charging. The first threshold temperature T1 is a set value of a temperature that is higher than the second threshold temperature T2 and is desirable to be reached during charging, and is set to about 5°C in the case of a lithium-ion battery. By setting it in this way, it is possible to provide hysteresis to the threshold temperature of the secondary battery 4 when deciding whether to start charging and when to stop charging.

[0025] The reference time tr is a set value for the maximum time for which the first threshold temperature T1 is continuously used, and is, for example, 5 seconds. As described below, when the first threshold temperature T1 is used as the threshold temperature for determining whether charging can be started and it is determined that charging cannot be started for a period of time equal to or longer than the reference time tr, the threshold temperature is switched to the second threshold temperature T2 to determine whether charging can be started. In other words, the threshold temperature for determining whether charging can be started is switched.

[0026] The I / O 624 mediates communication between the processor 621 and an external circuit. For example, the I / O 624 receives a power detection signal supplied from the charging circuit 61 and temperature data indicating the temperature TB of the secondary battery 4 supplied from the temperature sensor 5 as a temperature information acquisition unit, and transmits them to the processor 621. The I / O 624 also supplies a charge control signal output by the processor 621 to the charging circuit 61. The bus 625 transmits data between the processor 621 and the RAM 622, ROM 623, and I / O 624.

[0027] Next, the operation of the electronic device 1 having the above configuration will be described. When the connection plug of the AC adapter 2 is not connected to the input unit 3 of the electronic device 1, or when it is connected but not supplying power, the charge / discharge circuit 61 regulates the output voltage of the secondary battery 4 and supplies it to each internal circuit. The internal circuits operate by consuming the supplied power, and realize various functions of the electronic device 1.

[0028] On the other hand, when the connection plug of the AC adapter 2 is connected to the input unit 3 of the electronic device 1 and power is being supplied, the power is supplied to each internal circuit from the AC adapter 2. Each internal circuit consumes the supplied power to operate and realizes various functions of the electronic device 1.

[0029] When the charging circuit 61 detects the supply of power from the AC adapter 2, it outputs a power supply detection signal to the charging control unit 62.

[0030] The processor 621 of the charging control unit 62 receives a power supply detection signal via the I / O 624 and the bus 625. In response to the received power supply detection signal, the processor 621 executes a charging control program stored in the ROM 623, using the RAM 622 as a work memory. Hereinafter, the charging control process executed by the processor 621 to control the charging circuit 61 will be described with reference to the flowchart of FIG.

[0031] When the processor 621 starts the charging control process, it first instructs the charging circuit 61 to stop charging via the I / O 624 (step S110). This is to avoid charging until it is confirmed that the secondary battery 4 is in a chargeable state. In response to the instruction, the charging circuit 61 stops the charging operation by opening the current switch of the charging circuit, for example, and goes into a non-charging state.

[0032] Next, processor 621 resets and restarts an internal timer to measure the period during which charging is stopped (elapsed time ts) (step S120). Next, the processor 621 reads temperature data indicating the temperature TB of the secondary battery 4 from the temperature sensor 5 via the I / O 624, and records the data in the RAM 622 with a time stamp (step S130).

[0033] The processor 621 determines whether or not the temperature TB for the secondary battery 4 indicated by the temperature data is equal to or higher than a first threshold temperature T1 indicating a desirable temperature during charging (step S141).

[0034] When the processor 621 determines that the temperature TB related to the secondary battery 4 is equal to or higher than the first threshold temperature T1 (step S141: Yes), it instructs the charging circuit 61 to start charging via the I / O 624 (step S142). The charging circuit 61 starts charging the secondary battery 4 in accordance with the instruction. Note that even if the processor 621 instructs the charging circuit 61 to start charging, the charging circuit 61 does not necessarily start the charging operation due to factors such as the convenience of the processing of the charging circuit 61, the charging state of the secondary battery 4, and control of safety devices. Therefore, in one respect, instructing the charging circuit 61 to start charging is equivalent to allowing the start of charging. The same applies to the following charging operations.

[0035] On the other hand, when it is determined that the temperature TB of the secondary battery 4 is less than the first threshold temperature T1 (step S141: No), the processor 621 determines whether the elapsed time ts measured by the internal timer is equal to or greater than the reference time tr (step S143). Initially, ts < tr, and it is determined as No in step S143. The flow returns to step S130 and the same operation is repeated. Thus, after the power supply from the AC adapter 2 is started, when the temperature TB of the secondary battery 4 is lower than the first threshold temperature T1, the processor 621 repeats the processes of step S141, step S143, and step S130, and the state of stopping the charging of the secondary battery 4 is maintained.

[0036] If this state continues for the reference time tr, tr ≤ ts holds, and it is determined as Yes in step S143, and the process proceeds to step S150.

[0037] In step S150, the processor 621 reads temperature data from the temperature sensor 5 via the I / O 624.

[0038] Subsequently, the processor 621 determines whether the temperature TB of the secondary battery 4 indicated by the temperature data is equal to or greater than the second threshold temperature T2 (step S161).

[0039] When the processor 621 determines that the temperature TB of the secondary battery 4 indicated by the temperature data is equal to or greater than the second threshold temperature T2 (step S161: Yes), it instructs the charging circuit 61 to charge via the I / O 624 (step S170). That is, the start of charging is permitted. Also, the criterion for determining whether to permit the start of charging here is the second threshold temperature T2. Here, step S143 is an example of the first condition in the claims.

[0040] In response to the instruction, the charging circuit 61 charges the secondary battery 4 with the power provided from the AC adapter 2. Thereafter, the process returns to step S150 and the above-described process is repeated. Thereby, the secondary battery 4 is charged.

[0041] However, when the temperature TB related to the secondary battery 4 decreases due to a decrease in the ambient temperature or the like and becomes less than the second threshold temperature T2 (step S161: No), the process returns to step S110 and charging is stopped. Thereby, a situation in which charging is performed in a state where the temperature TB related to the secondary battery 4 is less than the second threshold temperature T2 and the secondary battery 4 is damaged is prevented. Further, thereby, the second threshold temperature T2 functions as a threshold temperature for determining whether or not to stop the charging operation.

[0042] During the execution of the above-described charge control process, when the secondary battery 4 is fully charged, the charging circuit 61 stops the charging operation and notifies the charge control unit 62 of the full charge. The charge control unit 62 responds to the notification, ends the charge control process, and enters the standby state.

[0043] Thereafter, when the secondary battery 4 becomes chargeable and power is being supplied from the AC adapter 2, the charging circuit 61 outputs a power detection signal to the charge control unit 62. The charge control unit 62 resumes the charge control process from step S110 in response to the power detection signal.

[0044] Next, the charge control process described above will be described with reference to a specific example. Here, as shown in FIG. 4, after the AC adapter 2 starts supplying power to the electronic device 1, the temperature TB related to the secondary battery 4 fluctuates between the first and second threshold temperatures T1 and T2 for a while, and once decreases below the second threshold temperature T2 and then rises again, this case will be described as an example.

[0045] Immediately after the power supply from the AC adapter 2 is started, the processor 621 starts the charge control process. At this stage, since T2 < TB < T1, it is determined as No in step S141, and since ts < tr, it is determined as No in step S143. Therefore, the processes of step S141, step S143, and step S130 are repeated, and the state where charging to the secondary battery 4 is not performed (non-charging state) continues.

[0046] If the non-charging state continues for the reference time tr, tr ≦ ts holds and it is determined as Yes in step S143. Therefore, the process proceeds to step S150. In FIG. 4, at this point, since T2 < TB, it is determined as Yes in step S161 and charging is started in step S170.

[0047] Thereafter, when the temperature TB of the secondary battery 4 temporarily decreases and TB < T2, it is determined as No in step S161, the process returns to step S110, charging is stopped, and the non-charging state is entered.

[0048] In the example of FIG. 4, thereafter, the temperature TB of the secondary battery 4 rises and enters a state where T2 < TB < T1. However, before the reference time tr elapses since the charging stop, T1 < TB and it becomes a Yes state, it is determined as T1 ≦ TB in step S141, and charging is restarted in step S142.

[0049] As described above, in the present embodiment, even if the temperature TB of the secondary battery 4 falls below the first threshold temperature T1 and enters the charge start prohibited state, when the reference time tr elapses and the temperature is equal to or higher than the lower second threshold temperature T2, charging is started. For this reason, the timing of starting charging is advanced and the period dedicated to charging becomes longer. That is, the time efficiency is improved. Further, since the temperature TB of the secondary battery 4 at the time of restarting charging is equal to or higher than the second threshold temperature T2, the secondary battery 4 is not damaged.

[0050] (Embodiment 2) In Embodiment 1, when the temperature TB of the secondary battery 4 is lower than the second threshold temperature T2, charging of the secondary battery 4 is not started. However, when charging is started, there are also secondary batteries 4 whose temperature TB rises in a short time and reaches a temperature suitable for charging. In view of this, a charging device 6 according to Embodiment 2 will be described in which charging is once performed when the temperature TB of the secondary battery 4 is low, and then charging is continued or interrupted according to the change in the temperature TB of the secondary battery 4 thereafter.

[0051] The basic configuration and basic operation of the electronic circuit according to this embodiment are substantially the same as those of the configuration and operation of Embodiment 1 shown in FIGS. 1 to 4. Therefore, the description will be centered on the differences from Embodiment 1 while referring to FIG. 5.

[0052] In Embodiment 2, a third threshold temperature T3 lower than the second threshold temperature T2 is preset and stored in the ROM 623 in advance. The third threshold temperature T3 is set, for example, as the lower limit value of the battery temperature that does not harm the secondary battery 4 in the case of short-time charging. When the secondary battery 4 is composed of a lithium-ion battery, the third threshold temperature T3 is set to, for example, -10°C. In this embodiment, charging is not performed at all unless the temperature TB of the secondary battery 4 is equal to or higher than the third threshold temperature T3. The third threshold temperature T3 is the charging lower limit temperature with the temperature further extended to a lower temperature compared to the second threshold temperature T2 which is a certain charging lower limit temperature.

[0053] When the connection plug of the AC adapter 2 is connected to the input unit 3, the processor 621 sequentially executes charging stop (step S110), reset and start of the internal timer (step S120), and reading of the temperature TB of the secondary battery 4 (step S130) in the same manner as the charging control process in FIG. 3.

[0054] Subsequently, in step S141, when it is determined that TB < T1 (step S141: No), the processor 621 determines whether the temperature TB of the secondary battery 4 is equal to or higher than the third threshold temperature T3 (step S201).

[0055] In step S201, when it is determined that the temperature TB of the secondary battery 4 is lower than the third threshold temperature T3 (step S201: No), the temperature TB of the secondary battery 4 is too low to be suitable for charging. Therefore, the process returns to step S130 and the same process is repeated. In this case, although the temperature TB of the secondary battery 4 is low, since charging has not started, there is no damage to the secondary battery 4.

[0056] On the other hand, in step S201, if it is determined that the temperature TB for the secondary battery 4 is equal to or higher than the third threshold temperature T3 (step S201: Yes), it is determined whether the elapsed time ts measured by the internal timer, i.e., the elapsed time ts since charging was stopped, is equal to or higher than the reference time tr (step S202).

[0057] In step S202, if it is determined that tr>ts (step S202: No), the process returns to step S130.

[0058] On the other hand, if it is determined in step S202 that tr≦ts (step S202: Yes), and if it is determined in step S141 that T1≦TB, charging is started (step S170). Therefore, at the start of charging, the temperature TB of the secondary battery 4 may be equal to or lower than the second threshold temperature T2. Here, steps S201 and S202 are an example of the first condition in the claims.

[0059] Next, the temperature data is read from the temperature sensor 5 (step S150), and it is determined whether or not the temperature TB related to the secondary battery 4 indicated by the temperature data is equal to or higher than the second threshold temperature T2 (step S161).

[0060] In step S161, if it is determined that the temperature TB for the secondary battery 4 is equal to or higher than the second threshold temperature T2 (step S161: Yes), the charging circuit 61 is instructed to continue charging, and the process returns to step S170.

[0061] On the other hand, when it is determined in step S161 that the temperature TB of the secondary battery 4 is less than the second threshold temperature T2 (step S161: No), the process waits for a certain period of time (step S203). The processor 621 then reads out the history of the temperature TB of the secondary battery 4 stored in the RAM 622 and reads the most recent temperature data from the temperature sensor 5 (step S204). Next, the processor 621 determines whether the temperature TB of the secondary battery 4 is increasing, i.e., ΔTB is a positive value, or whether the temperature TB of the secondary battery 4 is decreasing, i.e., ΔTB is a negative value, based on the read temperature data string (step S205). When the temperature TB of the secondary battery 4 is increasing, i.e., when the temperature TB is rising, there is a possibility that the temperature TB of the secondary battery 4 will rise to a temperature at which the secondary battery 4 can be safely charged if the process waits for a while. Therefore, when the temperature TB of the secondary battery 4 is increasing (step S205: Yes), the process proceeds to S170. On the other hand, if the temperature TB of the secondary battery 4 is decreasing (step S205: No), there is little or no possibility that the temperature TB of the secondary battery 4 will rise to a temperature at which charging is possible, so the process proceeds to S110 and charging is stopped. Here, step S205 is an example of the second condition in the claims.

[0062] As described above, in this embodiment, basically, the first threshold temperature T1 is set as the threshold temperature for determining whether charging can be started, and the second threshold temperature T2 is set as the threshold temperature for determining whether charging should be stopped, and hysteresis is provided to the threshold temperature. On the other hand, even if the temperature TB of the secondary battery 4 does not reach the first threshold temperature T1, if the non-charging state continues for the reference time tr or more, charging is started once, and the degree of rise in the temperature TB thereafter is determined. If there is a high possibility that the temperature TB of the secondary battery 4 will rise to a temperature suitable for charging, charging is continued. This allows charging to be performed earlier or for a longer period of time, improving time efficiency.

[0063] The waiting process of step S203 may be placed between steps S170 and S150.

[0064] It is possible to evaluate the rise in temperature TB of the secondary battery 4 in more detail.

[0065] In step S205, the conditions for continuing charging and the conditions for stopping charging can be determined arbitrarily. For example, a condition may be an arbitrary reference value<ΔTB. The magnitude of the difference between the temperature TB at that time and the second threshold temperature T may also be included in the conditions. Also, it may be determined that the condition for continuing charging is met when the change in battery temperature during the standby time t2, ΔTB / t2, i.e., the rate of increase in temperature TB of the secondary battery 4, i.e., the temperature increase rate, is greater than a reference value. Note that although it has been described here as the rate of increase being greater than the reference value, this means that the rate is higher than a reference that has an increasing tendency, and it may be specified by something other than a simple numerical value.

[0066] Also, for example, the second derivative d of the change in temperature TB of the secondary battery 4 2 TB / dt 2 is calculated, and when this is positive, that is, when the gradient of the temperature change is on the increase, the charging state may be started or continued even if ΔTB is negative.

[0067] In addition, the time required to reach the second threshold temperature T2 can be estimated from an approximation line of the temperature TB for the secondary battery 4, the estimated time can be compared with a reference value, and if the estimated time is less than the reference value, the condition can be set to start or continue the charging state.

[0068] In the above explanation, an example has been shown in which charging of the secondary battery 4 is started when it is determined in step S202 that tr≦ts (step S202: Yes). However, as shown in FIG. 6, it is also possible not to perform charging at this point. In this case, when it is determined in step S205 that the condition 0<ΔTB is satisfied due to, for example, an increase in the ambient temperature, charging is started (step S170).

[0069] (Embodiment 3) When the user connects the connection plug of the AC adapter 2 to the input unit 3, it is presumed that the user has a strong intention to charge the secondary battery 4. In this case, it may not be desirable to ignore the user's intention to charge simply based on the temperature condition. In this case, for example, immediately after connecting the plug to the input unit 3, it is desirable to charge the secondary battery 4, except when the temperature TB is extremely low. A charging device 6 that can satisfy such demands will now be described with reference to FIG.

[0070] The basic configuration and basic operation of the electronic circuit according to this embodiment are almost the same as those shown in Figures 1 to 4. Therefore, the following description will focus on the differences. In the present embodiment, after starting the charge control process, processor 621 first sets a first flag in RAM 622 (step S100), and thereafter executes the above-described steps S110 to S141.

[0071] Here, if it is determined in step S201 that T3≦TB (step S201: Yes), the processor 621 refers to the first-time flag set in the RAM 622 (step S211).

[0072] When a series of processes is executed for the first time after the start of the charge control process, it is determined in step S204 that the first flag is on. If processor 621 determines that the first flag is on (step S211: Yes), the process proceeds to step S170, and starts charging the secondary battery 4. The subsequent process is the same as the process in the second embodiment shown in FIG.

[0073] In addition, if processor 621 determines that the first-time flag is on in step S211 (step S211: Yes), if processor 621 determines that T3>TB in step S201 (step S201: No), or if processor 621 determines that T1≦TB in step S141 (step S141: Yes), it resets the first-time flag in RAM 622.

[0074] With this configuration, the secondary battery 4 can be charged at a high rate immediately after the supply of power from the AC adapter 2 to the charging device 6 is started. This makes it possible to reflect the user's intention. On the other hand, after a certain amount of charging has been performed, it becomes possible to implement charging control, including stopping charging, taking into account the temperature TB related to the secondary battery 4.

[0075] Note that, if it is determined as Yes in step S201 after processing such as step S205 other than the first time, the charging start condition based on the elapsed time ts shown in step S202 of Fig. 5 may be used in combination. Also, charging may be started not only for the first time, but also up to a certain upper limit number of times, such as up to the second time or up to the third time. Also, charging may not be started after a certain time has elapsed, but may be started within a certain time after the supply of power to the charging device 6 has started.

[0076] Although an example in which the first flag is used has been shown, the time that has elapsed since the AC adapter was connected may be measured, and for a certain period of time, the result of step S211 may be Yes, giving priority to charging.

[0077] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications and applications are possible.

[0078] In the above embodiment, an example is shown in which the charging control unit 62 is provided as the power supply circuit, but if a similar control function can be realized, a DSP (Digital Signal Processor) or the like can also be used. Also, a hardware form such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) may be used.

[0079] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-mentioned embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims, not the embodiments. Various modifications made within the scope of the claims and the scope of the invention equivalent thereto are considered to be within the scope of the present invention. The invention described in the original claims of this application is appended below.

[0080] (Additional Note) (Appendix 1) A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit includes: when a temperature related to the secondary battery is less than a first threshold temperature and a first condition is satisfied, allowing charging of the secondary battery to begin; When the temperature related to the secondary battery is less than the first threshold temperature and does not satisfy the first condition, the start of charging of the secondary battery is not permitted. Charging device.

[0081] (Appendix 2) The first condition includes that a state in which the temperature of the secondary battery is lower than the first threshold temperature continues for a first period of time or more. 2. A charging device as described in claim 1.

[0082] (Appendix 3) The first condition includes that the temperature of the secondary battery is equal to or higher than a lower limit temperature of charging when the first period of time continues. Charging device according to claim 1 or 2.

[0083] (Appendix 4) The first condition includes a certain period of time after the supply of power to the charging circuit. 4. A charging device according to any one of claims 1 to 3.

[0084] (Appendix 5) The first condition includes a condition after charging is once performed. 5. A charging device according to any one of claims 1 to 4.

[0085] (Appendix 6) The first condition includes any one of the following: the temperature of the secondary battery is on an increasing trend; the temperature increase rate is higher than a certain increase rate; and the slope of the temperature change is on an increasing trend. 6. A charging device according to any one of claims 1 to 5.

[0086] (Appendix 7) The charging control unit causes a charging circuit to: i) allow charging of the secondary battery to begin when a temperature related to the secondary battery is equal to or higher than the first threshold temperature; and ii) stop charging of the secondary battery when the temperature related to the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature. 7. A charging device according to any one of claims 1 to 6.

[0087] (Appendix 8) The first condition includes a calculated time to reach the second threshold temperature being less than a certain time. 8. The charging device of claim 7.

[0088] (Appendix 9) When the temperature of the secondary battery is between the first threshold temperature and the second threshold temperature, the charge control unit maintains the previous charged state and non-charged state, provided that other conditions are satisfied. 9. The charging device according to claim 7 or 8.

[0089] (Appendix 10) the charging control unit allows the start of charging of the secondary battery or continues charging when the temperature of the secondary battery is equal to or higher than the first threshold temperature; When the temperature of the secondary battery is less than the second threshold temperature and satisfies a second condition, the charging is permitted to continue. 10. A charging device according to any one of claims 7 to 9.

[0090] (Appendix 11) A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit controls the charging circuit, when the temperature of the secondary battery is equal to or higher than a first threshold temperature, allowing charging of the secondary battery to begin; allowing the charging to continue when the temperature of the secondary battery is below a second threshold temperature that is lower than the first threshold temperature and satisfies a second condition; When the temperature related to the secondary battery is less than the second threshold temperature and the second condition is not satisfied, charging is stopped. Charging device.

[0091] (Appendix 12) The second condition includes any one of the following: the temperature of the secondary battery is increasing; a temperature increase rate is higher than a certain increase rate; a temperature change gradient is increasing; and a calculated time to reach the second threshold temperature is shorter than a certain time. 12. The charging device according to claim 10 or 11.

[0092] (Appendix 13) The secondary battery is a lithium ion battery, and the first threshold temperature is 5° C. 13. A charging device according to any one of claims 1 to 12.

[0093] (Appendix 14) The secondary battery is a lithium ion battery, and the second threshold temperature is 0° C. 13. A charging device according to any one of claims 7 to 12.

[0094] (Appendix 15) The secondary battery; A charging device according to any one of appendices 1 to 14. An electronic device comprising:

[0095] (Appendix 16) Measure the temperature of the secondary battery; starting charging of the secondary battery when the temperature of the secondary battery is equal to or higher than a first threshold temperature and when the temperature of the secondary battery falls below the first threshold temperature and satisfies a first condition; when the temperature of the secondary battery is less than the first threshold temperature and the first condition is not satisfied, charging of the secondary battery is not started; when the temperature associated with the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature; When a second condition is satisfied, charging of the secondary battery is continued, and when the second condition is not satisfied, charging of the secondary battery is stopped. Charging method.

[0096] (Appendix 17) On the computer, A process of measuring the temperature of the secondary battery; i) a process of starting charging of the secondary battery when the temperature of the secondary battery is equal to or higher than a first threshold temperature and when the temperature of the secondary battery falls below the first threshold temperature and satisfies a first condition; ii) continuing to stop charging the secondary battery when the temperature of the secondary battery is below the first threshold temperature and the first condition is not satisfied; iii) when the temperature of the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature, a process is executed to continue charging the secondary battery if a second condition is satisfied, and to stop charging the secondary battery if the second condition is not satisfied. Computer program.

[0097] (Appendix 18) The first condition is the temperature of the secondary battery remains below the first threshold temperature for a certain period of time or more; a certain period of time has passed since power was supplied to a charging circuit; the temperature of the secondary battery is on an upward trend; the rate of temperature increase is higher than a certain rate of increase; the slope of the temperature change is on an upward trend; the calculated time until the second threshold temperature is reached is shorter than a certain period of time; or a condition that occurs after charging is performed once, The second condition is The temperature of the secondary battery is on an upward trend, the rate of temperature increase is higher than a certain rate of increase, the slope of the temperature change is on an upward trend, or the calculated time until the second threshold temperature is reached is shorter than a certain time. 18. The charging method according to claim 16 or the computer program according to claim 17. [Explanation of symbols]

[0098] 1...electronic device, 2...AC adapter, 3...input section, 4...secondary battery, 5...temperature sensor, 6...charging device, 61...charging circuit, 62...charging control section, 621...processor, 622...RAM, 623...ROM, 624...I / O, 625...bus, T1...first threshold temperature, T2...second threshold temperature, T3...third threshold temperature, TB...temperature related to the secondary battery, t2...standby time, tr...reference time, ts...elapsed time

Claims

1. A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit is the charging circuit permits charging of the secondary battery when a temperature related to the secondary battery is less than a first threshold temperature and a first condition related to the temperature of the secondary battery is satisfied; when the temperature related to the secondary battery is less than the first threshold temperature and the first condition is not satisfied, charging of the secondary battery is not permitted; a charging circuit that: i) permits charging of the secondary battery when a temperature related to the secondary battery is equal to or higher than the first threshold temperature; and ii) stops charging of the secondary battery when the temperature related to the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature; The first condition is that the calculated time to reach the second threshold temperature is less than a certain time. Charging device.

2. A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit is the charging circuit permits charging of the secondary battery when a temperature related to the secondary battery is less than a first threshold temperature and a first condition related to the temperature of the secondary battery is satisfied; when the temperature related to the secondary battery is less than the first threshold temperature and the first condition is not satisfied, charging of the secondary battery is not permitted; a charging circuit that: i) permits charging of the secondary battery when a temperature related to the secondary battery is equal to or higher than the first threshold temperature; and ii) stops charging of the secondary battery when the temperature related to the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature; When the temperature of the secondary battery is lower than the second threshold temperature, a fixed time is waited, and after waiting for the fixed time, charging is permitted if any of the following conditions is satisfied: the temperature of the secondary battery is on an increasing trend, the rate of temperature increase is higher than a certain rate of increase, the gradient of the temperature change is on an increasing trend, and the calculated time until the second threshold temperature is reached is shorter than a certain time. Charging device.

3. The first condition is that a state in which the temperature of the secondary battery is below the first threshold temperature continues for a certain first time or more, and the temperature of the secondary battery when the state continues for the first time or more is equal to or higher than a certain lower limit temperature of charging. The charging device according to claim 2.

4. The first condition is that the secondary battery is once charged, and after the charging is performed, the temperature of the secondary battery is on an increasing trend, the temperature increase rate is higher than a certain increase rate, or the slope of the temperature change is on an increasing trend. The charging device according to claim 2.

5. A charging circuit for charging the secondary battery; a temperature information acquisition unit that acquires temperature information indicating a temperature related to the secondary battery, and a charge control unit that controls the charging circuit based on the temperature information acquired by the temperature information acquisition unit; The charging control unit controls the charging circuit, When the temperature of the secondary battery is equal to or higher than a first threshold temperature, charging of the secondary battery is permitted; permitting charging when the temperature of the secondary battery is less than a second threshold temperature that is lower than the first threshold temperature and a second condition regarding the temperature of the secondary battery is satisfied; When the temperature of the secondary battery is less than the second threshold temperature and the second condition is not satisfied, charging is stopped; The second condition is any one of the following: the temperature of the secondary battery is increasing; the rate of temperature increase is higher than a certain rate of increase; the slope of the temperature change is increasing; and the calculated time until the second threshold temperature is reached is shorter than a certain time. Charging device.

6. The secondary battery is a lithium ion battery, and the first threshold temperature is 5° C. The charging device according to any one of claims 1 to 5.

7. The secondary battery is a lithium ion battery, and the second threshold temperature is 0° C. The charging device according to any one of claims 1 to 6.

8. The secondary battery; The charging device according to any one of claims 1 to 7, An electronic device comprising:

9. Measure the temperature of the secondary battery; charging the secondary battery when the temperature of the secondary battery is equal to or higher than a first threshold temperature and when the temperature of the secondary battery is below the first threshold temperature and satisfies a first condition related to the temperature of the secondary battery; When the temperature of the secondary battery is less than the first threshold temperature and the first condition is not satisfied, the secondary battery is not charged; when the temperature of the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature, charging the secondary battery when a second condition related to the temperature of the secondary battery is satisfied, and stopping charging the secondary battery when the second condition is not satisfied; The first condition is any one of the following: the temperature of the secondary battery remains below the first threshold temperature for a certain first period of time or more; the temperature of the secondary battery is on an increasing trend; the rate of temperature increase is higher than a certain rate of increase; the slope of the temperature change is on an increasing trend; and the calculated time until the second threshold temperature is reached is shorter than a certain period of time. The second condition is The temperature of the secondary battery is on an increasing trend, the rate of temperature increase is higher than a certain rate of increase, the slope of the temperature change is on an increasing trend, or the calculated time until the second threshold temperature is reached is shorter than a certain time. Charging method.

10. On the computer, A process of measuring the temperature of the secondary battery; i) charging the secondary battery when the temperature of the secondary battery is equal to or higher than a first threshold temperature and when the temperature of the secondary battery is below the first threshold temperature and satisfies a first condition related to the temperature of the secondary battery; ii) a process of continuing to stop charging of the secondary battery when the temperature of the secondary battery is below the first threshold temperature and the first condition is not satisfied; iii) when the temperature of the secondary battery falls below a second threshold temperature that is lower than the first threshold temperature, charging the secondary battery if a second condition related to the temperature of the secondary battery is satisfied, and stopping charging of the secondary battery if the second condition is not satisfied; The first condition is any one of the following: the temperature of the secondary battery remains below the first threshold temperature for a certain first period of time or more; the temperature of the secondary battery is on an increasing trend; the rate of temperature increase is higher than a certain rate of increase; the slope of the temperature change is on an increasing trend; and the calculated time until the second threshold temperature is reached is shorter than a certain period of time. The second condition is The temperature of the secondary battery is on an increasing trend, the rate of temperature increase is higher than a certain rate of increase, the slope of the temperature change is on an increasing trend, or the calculated time until the second threshold temperature is reached is shorter than a certain time. Computer program.

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