Electronic device and its control method

Abstract

This electronic device is provided with a battery pack, a charging circuit for charging the battery pack, a load device operating by the electric power of the battery pack, a voltage sensor for detecting the charging voltage and the discharge voltage of the battery pack, a current sensor for detecting the charging current and the discharge current of the battery pack, and a control circuit. The control circuit calculates the internal resistance of the battery pack on the basis of the charging voltage and the charging current, calculates, on the basis of the discharge voltage, the discharge current, and the internal resistance, a permissible electric power indicating the maximum electric power the load device may receive from the battery pack, and sends a control signal to the load device such that the load device operates at an electric power that is less than or equal to the permissible electric power.

Description

Technical Field

[0001] The present disclosure relates to an electronic device and a control method thereof.

Background Art

[0002] An electronic device such as a portable personal computer operates on electric power supplied by a mounted or connected storage battery. Such an electronic device is required to control its power consumption so as to operate within the range of electric power that can be supplied by the storage battery.

[0003] Patent Document 1 discloses a technique for controlling the peak power in an electronic device including a plurality of processors operating as master devices and a plurality of devices operating as slave devices. When the electronic device of Patent Document 1 operates on electric power supplied by a battery device, the processor is permitted to use the device when the total power consumption of the device is equal to or less than a predetermined value calculated from the remaining battery level.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] A storage battery deteriorates by continuous use, and as a result, the available electric power and the amount of electric energy decrease. Therefore, when calculating the remaining energy of the storage battery based only on the design value of the storage battery, if the storage battery deteriorates, it becomes impossible to accurately calculate the electric power that can be supplied by the storage battery.

[0006] The present disclosure provides an electronic device and a control method thereof that can control power consumption with higher accuracy than before.

[0007] An electronic device according to one aspect of the present disclosure is a storage battery, and A charging circuit for charging the storage battery, A load device operated by the power of the storage battery, A voltage sensor for detecting the charging voltage and the discharging voltage of the storage battery, A current sensor for detecting the charging current and the discharging current of the storage battery, And a control circuit, The control circuit, Calculates the internal resistance of the storage battery based on the charging voltage and the charging current, Based on the discharging voltage, the discharging current, and the internal resistance, calculates an allowable power indicating the maximum power that the load device can obtain from the storage battery, Sends a control signal to the load device so that the load device operates with power equal to or less than the allowable power.

[0008] According to the electronic device according to an aspect of the present disclosure, power consumption can be controlled with higher accuracy than in the past.

Brief Description of Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art.

[0011] Note that the inventors provide the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and do not intend to limit the subject matter described in the claims thereby.

[0012] [Embodiment] [Configuration of Embodiment] FIG. 1 is a block diagram showing the configuration of an electronic device 1 according to an embodiment. The electronic device 1 includes a battery pack 12 and can operate with the power supplied by the battery pack 12. The electronic device 1 may be, for example, a portable personal computer (e.g., a notebook computer, a tablet computer), a mobile phone, or the like. The electronic device 1 is connected to an AC power supply 2 via an AC / DC converter 3. The AC / DC converter 3 converts the AC power supplied from the AC power supply 2 into DC power and supplies it to the electronic device 1. The electronic device 1 operates with the power supplied from the AC / DC converter 3 and also charges the internal battery pack 12.

[0013] The electronic device 1 includes a charging circuit 11, a battery pack 12, a DC / DC converter 13, a control circuit 14, a switch SW, and a load device 20.

[0014] In FIG. 1, thick lines indicate power lines and thin lines indicate signal lines.

[0015] The charging circuit 11 charges the battery pack 12 with the power supplied from the AC / DC converter 3. The charging circuit 11 supplies power to the battery pack 12 with a variable voltage and a variable current according to the charging rate of the battery pack 12, for example, in any one of a constant current mode, a constant voltage mode, and a constant power mode.

[0016] The battery pack 12 includes a plurality of battery cells 12a, a current sensor 12b, a voltage sensor 12c, a temperature sensor 12d, and a nonvolatile memory 12e. Each battery cell 12a is a rechargeable secondary battery. The plurality of battery cells 12a are connected in series and / or in parallel with each other and have a predetermined internal resistance Rd as a whole. The internal resistance Rd of the battery pack 12 is calculated by the control circuit 14 as described later. The current sensor 12b detects the current supplied from the charging circuit 11 to the battery pack 12 (hereinafter also referred to as the "charging current Ib" of the battery pack 12) and notifies the charging circuit 11 and the control circuit 14. Also, the current sensor 12b detects the current supplied from the battery pack 12 to the load device 20 via the DC / DC converter 13 (hereinafter also referred to as the "discharge current Id" of the battery pack 12) and notifies the control circuit 14. The voltage sensor 12c detects the voltage across the positive and negative electrodes of the battery pack 12 and notifies the charging circuit 11 and the control circuit 14. Hereinafter, the voltage of the battery pack 12 during charging and discharging is also referred to as the "charging voltage Vb" and the "discharge voltage Vd" of the battery pack 12, respectively. The temperature sensor 12d detects the temperature of each battery cell 12a and notifies the control circuit 14. The nonvolatile memory 12e stores the internal resistance Rd of the battery pack 12 calculated by the control circuit 14.

[0017] The battery pack 12 may be configured to be detachable from the electronic device 1 or may be built into the electronic device 1.

[0018] The battery pack 12 is an example of a storage battery.

[0019] The switch SW selectively supplies, under the control of the control circuit 14, either the power supplied from the AC / DC converter 3 or the power discharged from the battery pack 12 to the DC / DC converter 13.

[0020] The DC / DC converter 13 generates one DC voltage or a plurality of different DC voltages by the power supplied from the AC / DC converter 3 or the power discharged from the battery pack 12, and supplies the generated DC voltage to the load device 20.

[0021] The control circuit 14 controls the operations of the charging circuit 11, the switch SW, and the central processing unit (CPU) 21 of the load device 20. The control circuit 14 may be, for example, a microcontroller of a type called an EC (Embedded Controller) for a computer.

[0022] The load device 20 includes a central processing unit (CPU) 21, a memory 22, a storage device 23, a display device 24, an input device 25, and a communication interface (I / F) 26. The CPU 21 executes a program stored in the storage device 23 and controls the operations of the other components 22 to 26 of the load device 20. The memory 22 temporarily stores programs and data necessary for the operation of the electronic device 1. The storage device 23 stores programs and data necessary for the operation of the electronic device 1. The storage device 23 may include, for example, a solid state drive or a hard disk drive. The display device 24 displays the results of the program executed by the CPU 21. The input device 25 receives user input for controlling the operation of the electronic device 1. The input device 25 includes, for example, a keyboard and a pointing device. The communication interface 26 is communicably connected to an external device via a wired line and / or a wireless line. The communication interface 26 may include an interface for connecting to peripheral devices, such as a USB (Universal Serial Bus).

[0023] The CPU 21 has a plurality of performance states that operate with different powers respectively. These performance states may be, for example, Px performance states (x = 0, 1, …, n) defined by the ACPI (Advanced Configuration and Power Interface) specification. Here, "n" is a predetermined maximum value depending on the CPU 21. In the P0 performance state, the CPU 21 operates at its maximum performance and consumes the maximum power. In the P1 performance state, the CPU 21 operates at a lower performance than in the P0 performance state and operates with less power than in the P0 performance state. Thereafter, as the number of "Px" increases, the performance and power consumption of the CPU 21 decrease. In the Pn performance state, the CPU 21 operates at its lowest performance and consumes the minimum power while maintaining an active state.

[0024] The CPU 21 is an example of an arithmetic circuit.

[0025] FIG. 2 is a block diagram showing the configuration of the charging circuit 11 in FIG. 1. The charging circuit 11 includes a DC / DC converter 31, a charge control circuit 32, a reference voltage source 33, and a comparator 34. The DC / DC converter 31 is, for example, a step-up / step-down type power converter including a plurality of switching elements, an inductor, a pulse width modulation circuit, and the like. The charge control circuit 32 controls the operation of the DC / DC converter 31 based on the charging voltage Vb detected by the voltage sensor 12c and the charging current Ib detected by the current sensor 12b. Specifically, the charge control circuit 32 calculates the charging rate of the battery pack 12 based on the charging voltage Vb and the charging current Ib, and controls the switching frequency and duty ratio of each switching element of the DC / DC converter 31 so as to generate a desired voltage and a desired current according to the charging rate. Further, the charge control circuit 32 temporarily stops and resumes the charging of the battery pack 12 according to the control signal from the control circuit 14. The reference voltage source 33 generates a reference voltage representing a predetermined threshold voltage Vmin. The threshold voltage Vmin indicates a low voltage at which there is a possibility of an interruption occurring in the electronic device 1. The comparator 34 generates an interrupt signal and sends it to the control circuit 14 and the CPU 21 when the discharge voltage Vd detected by the voltage sensor 12c becomes smaller than the threshold voltage Vmin.

[0026] Referring again to FIG. 1, the control circuit 14 calculates the internal resistance Rd of the battery pack 12 based on the charging voltage Vb and the charging current Ib of the battery pack 12. The control circuit 14 calculates an allowable power W indicating the maximum power that the CPU 21 can obtain from the battery pack 12 based on the discharge voltage Vd, the discharge current Id, and the internal resistance Rd of the battery pack 12. The control circuit 14 sends a control signal to the CPU 21 so that the CPU 21 operates with power equal to or less than the allowable power W.

[0027] Further, when the discharge voltage Vd of the battery pack 12 decreases and there is a possibility of an interruption occurring in the electronic device 1, the control circuit 14 corrects the internal resistance Rd and recalculates the allowable power W.

[0028] The CPU 21 selectively operates in one of a plurality of performance states in accordance with a control signal from the control circuit 14 so that the CPU 21 operates with power equal to or less than the allowable power.

[0029] For the purpose of thermal management of the CPU 21, the control circuit 14 may set some threshold power for the CPU 21. For example, the threshold power of PL4 (Power Limit 4) used by the intel (registered trademark) core processor of Intel Corporation may be set, and the operating frequency of the CPU 21 may be limited to prevent a power spike exceeding PL4.

[0030] [Operation of the Embodiment] The control circuit 14 controls the operation of the electronic device 1 by executing a charge control process, a discharge control process, and an interrupt process described below.

[0031] [Charge Control Process] FIG. 3 is a flowchart showing the charge control process executed by the control circuit 14 of FIG. 1. The battery pack 12 deteriorates and the internal resistance Rd increases as it continues to be used. As a result, the available power and the amount of electric power decrease. In the charge control process, the control circuit 14 measures the internal resistance Rd of the battery pack 12 while charging the battery pack 12.

[0032] In step S1, the control circuit 14 sets the parameter i to 1. In the present embodiment, in order to measure the internal resistance of the battery pack 12, the control circuit 14 measures the internal resistance a plurality of N times during charging of the battery pack 12 and calculates the average of the plurality of internal resistances. The parameter i is a parameter representing the number of times of measuring the internal resistance.

[0033] In step S2, the control circuit 14 sets a threshold Th(i) of the charge rate of the battery pack 12. In the present embodiment, the control circuit 14 measures the internal resistance Ra(i) of the battery pack 12 each time the charge rate of the battery pack 12 reaches any one of a plurality of predetermined thresholds Th(i).

[0034] Figure 4 is a graph for explaining the calculation of internal resistances Ra(1) to Ra(6) by repeatedly executing steps S1 to S11 in FIG. 3. In the example of FIG. 4, for the state of charge of the battery pack 12, six thresholds Th(1) = 65%, Th(2) = 70%, Th(3) = 75%, Th(4) = 80%, Th(5) = 85%, and Th(6) = 90% are used. That is, the plurality of thresholds Th(i) are values corresponding to the number of repetitions of steps S1 to S11 (parameter i: number of times of measuring the internal resistance). Here, as the parameter i increases, the plurality of thresholds Th(i) increase. In the example of FIG. 4, each time the state of charge of the battery pack 12 reaches the thresholds Th(1) to Th(6), the control circuit 14 measures the corresponding internal resistances Ra(1) to Ra(6) of the battery pack 12, respectively.

[0035] Referring again to FIG. 3, in step S3, the control circuit 14 measures the charging voltage Vb of the battery pack 12 using the voltage sensor 12c, and measures the charging current Ib of the battery pack 12 using the current sensor 12b. The control circuit 14 may periodically measure the charging voltage Vb and the charging current Ib, for example, at a frequency of several tens of milliseconds to several hundreds of milliseconds. Further in step S3, the control circuit 14 calculates the state of charge of the battery pack 12 based on the charging voltage Vb of the battery pack 12. Basically, since there is a certain relationship between the voltage of the storage battery and the state of charge, the state of charge can be estimated from the voltage.

[0036] In step S4, the control circuit 14 determines whether or not the state of charge of the battery pack 12 has reached the threshold Th(i). If YES, the process proceeds to step S5. If NO, the process returns to step S3.

[0037] In step S5, the control circuit 14 controls the charging circuit 11 to temporarily stop the charging of the battery pack 12.

[0038] In step S6, after the elapse of a predetermined waiting time of 1 second or less since the charging of the battery pack 12 is stopped, the control circuit 14 detects the voltage Va of the battery pack 12 using the voltage sensor 12c.

[0039] In step S7, the control circuit 14 measures the temperature Temp of each battery cell 12a using the temperature sensor 12d.

[0040] In step S8, the control circuit 14 calculates the internal resistance Ra(i) of the battery pack 12 based on the voltages Va and Vb, the current Ib, and the temperature Temp of the battery pack 12.

[0041] FIG. 5 is a graph for explaining the calculation of the internal resistance Ra(i) by executing steps S3 to S8 in FIG. 3. The upper part of FIG. 5 shows the voltage of the battery pack 12 detected by the voltage sensor 12c, and the lower part of FIG. 5 shows the current of the battery pack 12 detected by the current sensor 12b. In the example of FIG. 5, when the voltage of the battery pack 12 reaches the voltage Vb, the state of charge of the battery pack 12 reaches the threshold value Th(i). For this reason, at time t1, the charging of the battery pack 12 is temporarily stopped, and the current of the battery pack 12 becomes zero. The control circuit 14 acquires the voltage Vb and the current Ib immediately before the charging of the battery pack 12 is stopped. Thereafter, after the elapse of a waiting time of 1 second since the charging of the battery pack 12 is stopped, at time t2, the control circuit 14 acquires the voltage Va of the battery pack 12. The control circuit 14 calculates the internal resistance Ra(i) by dividing the potential difference between the voltages Vb and Va by the current Ib as shown in the following equation. In one example, "immediately before" the charging of the battery pack 12 is stopped means a time within 1 second from time t1. Ra(i)=(Vb-Va) / Ib The internal resistance of the battery pack 12 is represented by the complex impedance Z = R + jX and can be decomposed into a resistance component R and a reactance component X. If the contribution of the reactance component X in the calculation of the internal resistance is large, the calculated value of the internal resistance will be excessive, and the power that can be supplied by the battery pack 12 will be underestimated. Therefore, it is required to reduce the contribution of the reactance component X in the calculation of the internal resistance and calculate the internal resistance solely based on the resistance component R. The inventors of the present invention experimentally confirmed that by calculating the internal resistance Ra(i) based on the potential difference between the voltage Vb immediately before stopping the charging of the battery pack 12 and the voltage Va after the elapse of a waiting time of 1 second or less after stopping the charging of the battery pack 12, the contribution of the reactance component X can be reduced and only the resistance component R can be extracted.

[0042] FIG. 6 is a table showing the correction coefficient regarding the temperature Temp of the battery cell 12a used in step S8 of FIG. 3. When the temperature Temp of each battery cell 12a fluctuates, the power that can be supplied by the battery pack 12 also fluctuates. Therefore, the control circuit 14 corrects the internal resistance Ra(i) based on the temperature Temp of the battery cell 12a. Specifically, the control circuit 14 multiplies the internal resistance Ra(i) by a correction coefficient k according to the temperature Temp of each battery cell 12a when the internal resistance Ra(i) is measured. In the example of FIG. 6, the temperature Temp gradually increases in the order of T1 < 25 degrees < T2 < T3. The correction coefficient k is set to convert the internal resistance measured at each temperature T1, T2, T3 into the internal resistance measured at a normal temperature of 25°C.

[0043] Referring to FIG. 3 again, in step S9, after detecting the voltage Va, the control circuit 14 controls the charging circuit 11 to resume the charging of the battery pack 12 (refer to time t3 in FIG. 5). The control circuit 14 may resume the charging of the battery pack 12, for example, 60 seconds after stopping the charging of the battery pack 12.

[0044] In step S10, the control circuit 14 determines whether the parameter i has reached a predetermined maximum value N (in the example of FIG. 4, N = 6). If YES, it proceeds to step S12; if NO, it proceeds to step S11. In other words, in step S10, the control circuit 14 determines whether it has calculated all the internal resistances Ra(i) corresponding to all the predetermined threshold values Th(i).

[0045] In step S11, the control circuit 14 increments the parameter i by 1 and returns to step S2. The control circuit 14 repeats the temporary stop of the charging of the battery pack 12 (step S5), the calculation of the internal resistance Ra(i) (step S8), and the resumption of the charging of the battery pack 12 (step S9) to obtain a plurality of internal resistances Ra(1) to Ra(N).

[0046] In step S12, the control circuit 14 calculates the internal resistance Rm based on the average of the internal resistances Ra(1) to Ra(N). For example, as shown in FIG. 4, when the internal resistance Ra(i) is measured six times during the charging of the battery pack 12, the average internal resistance Rm is calculated by the following formula. Rm = [Ra(1) + Ra(2) + … + Ra(6)] / 6 Before calculating the average internal resistance Rm, the control circuit 14 may determine whether the obtained internal resistances Ra(1) to Ra(N) are outliers. In this case, the control circuit 14 excludes the internal resistance Ra(i) that is an outlier and calculates the internal resistance Rm based on the average of the remaining internal resistances Ra(j) (1 ≤ j ≤ N, i ≠ j).

[0047] Also, the control circuit 14 may preset a lower limit value Rmin and an upper limit value Rmax of the allowable internal resistance. When the calculated internal resistance Rm is smaller than the lower limit value Rmin or larger than the upper limit value Rmax, the value of the internal resistance Rm may be rounded. For example, when Rm > Rmax, the measurement result may be processed as Rm = Rmax.

[0048] In step S13, the control circuit 14 reads out the previously calculated internal resistance Rd from the non-volatile memory 12e as the internal resistance Rd(old).

[0049] In step S14, the control circuit 14 calculates the updated internal resistance Rd(new) by the moving average of the previously calculated internal resistance Rd(old) and the newly calculated internal resistance Rm. For example, when giving a weight of 3 / 4 to the previously calculated internal resistance Rd(old), the updated internal resistance Rd(new) is calculated by the following formula. Rd(new)=Rd(old)×3 / 4+Rm×1 / 4 As described above, the control circuit 14 calculates the weighted moving average as the updated internal resistance Rd(new) using the previously calculated internal resistance Rd(old), the weight of the internal resistance Rd(old) (3 / 4), the newly calculated internal resistance Rm, and the weight of the internal resistance Rm (1 / 4). In step S15, the control circuit 14 stores the updated internal resistance Rd(new) as the internal resistance Rd in the non-volatile memory 12e and ends the process.

[0050] According to the charge control process of FIG. 3, the internal resistance Rd of the battery pack 12 can be measured while charging the battery pack 12.

[0051] According to the charge control process of FIG. 3, by calculating the internal resistance Ra(i) based on the potential difference between the voltage Vb immediately before stopping the charging of the battery pack 12 and the voltage Va after the elapse of a standby time of 1 second or less after stopping the charging of the battery pack 12, the contribution of the reactance component X can be reduced and only the resistance component R can be extracted. Therefore, according to the charge control process of FIG. 3, the internal resistance Rd of the battery pack 12 can be measured with high accuracy.

[0052] In the charging control process of FIG. 3, the waiting time from when the charging of the battery pack 12 is stopped until the voltage Va is measured is set such that the resistance component R of the internal resistance Rd includes high-frequency components caused by, for example, the electrolyte movement resistance, the lead resistance, and the charge transfer resistance. The lower limit of the waiting time is set to be longer than the duration of the load generated during control. The upper limit of the waiting time is arbitrary, but increasing the waiting time will, as described above, increase the contribution of the reactance component X in the calculation of the internal resistance, causing the calculated value of the internal resistance to become excessive and resulting in an underestimated power that can be supplied by the battery pack 12.

[0053] If the electronic device 1 is connected to the AC power supply 2 via the AC / DC converter 3, the control circuit 14 may execute the charging control process of FIG. 3 even when the power of the electronic device 1 is turned off. Thereby, even when the power of the electronic device 1 is turned off, the battery pack 12 can be charged and the internal resistance Rd of the battery pack 12 can be measured.

[0054] [Discharge Control Process] FIG. 7 is a flowchart showing the discharge control process executed by the control circuit 14 of FIG. 1. The discharge control process is executed to supply power from the battery pack 12 to the load device 20 when the power supply from the external AC power supply 2 and the AC / DC converter 3 to the electronic device 1 stops.

[0055] In step S21, when the power supply from the external AC power supply 2 and the AC / DC converter 3 to the electronic device 1 stops, the control circuit 14 controls the switch SW to start discharging from the battery pack 12. Alternatively, when the power of the electronic device 1 is turned on while the electronic device 1 is not connected to the AC power supply 2 and the AC / DC converter 3, the control circuit 14 may start discharging from the battery pack 12.

[0056] In step S22, the control circuit 14 reads the internal resistance Rd from the non-volatile memory 12e.

[0057] In step S23, the control circuit 14 measures the discharge voltage Vd of the battery pack 12 using the voltage sensor 12c, measures the discharge current Id of the battery pack 12 using the current sensor 12b, and measures the temperature Temp of the battery pack 12 using the temperature sensor 12d.

[0058] In step S24, the control circuit 14 determines, based on the discharge voltage Vd and the discharge current Id of the battery pack 12, which of the plurality of charge rate ranges Cd the charge rate is included in.

[0059] FIG. 8 is a table used to calculate the charge rate range Cd in step S24 of FIG. 7. In the example of FIG. 8, Cd0 represents a charge rate of 0 to 49%, Cd50 represents a charge rate of 50 to 79%, and Cd80 represents a charge rate of 80 to 100%. The control circuit 14 determines, based on the discharge voltage Vd and the discharge current Id, which of the charge rate ranges Cd0, Cd50, and Cd80 the charge rate is included in.

[0060] As described above, basically, there is a certain relationship between the voltage of the storage battery and the charge rate, and if there is no load, the charge rate can be estimated from the voltage. However, when there is a load, that is, when a discharge current (or a charge current) is flowing, the voltage is displaced according to the magnitude of the flowing current, so the magnitude of the current is also referred to in order to determine the charge rate range Cd.

[0061] Referring to FIG. 7 again, in step S25, the control circuit 14 determines the maximum power W1 that can be output from the battery pack 12 based on the charge rate range Cd and the temperature Temp of the battery pack 12. The maximum power W1 indicates the maximum power that can be output from the battery pack 12 when the internal resistance Rd of the battery pack 12 is equal to the maximum value Rmax.

[0062] FIG. 9 is a table used to determine the maximum power W1 that can be output from the battery pack 12 in step S25 of FIG. 7. The control circuit 14 determines which of 10W, 20W, 30W, 40W, and 45W the maximum power W1 is based on the charge rate range Cd and the temperature Temp.

[0063] Referring again to FIG. 7, in step S26, the control circuit 14 calculates an allowable power W indicating the maximum power that the CPU 21 can obtain from the battery pack 12 using the following equation based on the maximum power W1 that can be output from the battery pack 12 and the internal resistance Rd of the battery pack 12. W=(W1-W2)×((Rmax+Re) / (Rd+Re))+W2 Here, W2 indicates the minimum power that must be output from the battery pack 12, including the power consumed by components other than the CPU 21 of the electronic device 1. Also, Re indicates the circuit resistance of the electronic device 1 other than the internal resistance Rd of the battery pack 12.

[0064] As described above, the maximum power W1 that can be output from the battery pack 12 is determined based on the charge rate range Cd of the battery pack 12, and the charge rate range Cd is determined based on the discharge voltage Vd and the discharge current Id of the battery pack 12. Therefore, equivalently, the allowable power W is determined based on the discharge voltage Vd, the discharge current Id, and the internal resistance Cd of the battery pack 12. Also, since the maximum power W1 that can be output from the battery pack 12 is determined based on the temperature Temp of the battery pack 12, equivalently, the allowable power W is corrected by the temperature Temp.

[0065] In step S27, the control circuit 14 sets the allowable power W to the CPU 21. Thereby, the CPU 21 is set to one of a plurality of performance states so as to obtain only power equal to or less than the allowable power W from the battery pack 12.

[0066] In step S28, the control circuit 14 measures the discharge voltage Vd of the battery pack 12 using the voltage sensor 12c, measures the discharge current Id of the battery pack 12 using the current sensor 12b, and measures the temperature Temp of the battery pack 12 using the temperature sensor 12d.

[0067] In step S29, the control circuit 14 determines whether any of the discharge voltage Vd, discharge current Id, and temperature Temp measured in step S28 have significantly changed from the previously measured corresponding values. If YES, it returns to step S24; if NO, it returns to step S28. Here, "significantly change" means that the discharge voltage Vd or discharge current Id changes as much as is necessary to change the charge rate range Cd in the table of FIG. 8, or that the charge rate range Cd or temperature Temp changes as much as is necessary to change the maximum power W1 in the table of FIG. 9.

[0068] According to the discharge control process of FIG. 7, the allowable power of the CPU 21 can be set based on the internal resistance Rd of the battery pack 12 measured by performing the charge control process of FIG. 3. Thereby, based on the accurate internal resistance Rd, the power consumption of the CPU 21 can be controlled with higher precision than before.

[0069] [Interrupt processing] FIG. 10 is a flowchart showing the interrupt processing executed by the control circuit 14 of FIG. 1. The interrupt processing is executed when the electronic device 1 is operating with the power discharged from the battery pack 12 (that is, during the execution of the discharge control process of FIG. 7), when there is a risk that the discharge voltage of the battery pack 12 will drop and cause an interruption of the electronic device 1.

[0070] As described above, when the discharge voltage Vd detected by the voltage sensor 12c becomes smaller than the threshold voltage Vmin, the charging circuit 11 generates an interrupt signal and sends it to the control circuit 14 and the CPU 21.

[0071] The interrupt signal may be, for example, the prochot signal used by an intel core processor of Intel Corporation. The prochot signal is asserted when the processor is at a high temperature and causes the processor to transition to the Pn performance state. By using the prochot signal, the CPU 21 can operate at its minimum performance while maintaining the active state and transition to a state that consumes the minimum power, thereby avoiding momentary interruption of the electronic device 1.

[0072] In step S31, the control circuit 14 receives an interrupt signal from the charging circuit 11.

[0073] In step S32, the control circuit 14 reads the internal resistance Rd from the non-volatile memory 12e.

[0074] In step S33, the control circuit 14 corrects the internal resistance Rd so as to increase the internal resistance Rd by a predetermined correction factor greater than 1, for example 1.05.

[0075] In step S34, the control circuit 14 stores the corrected internal resistance Rd in the non-volatile memory 12e.

[0076] In step S35, the control circuit 14 measures the discharge voltage Vd of the battery pack 12 using the voltage sensor 12c, measures the discharge current Id of the battery pack 12 using the current sensor 12b, and measures the temperature Temp of the battery pack 12 using the temperature sensor 12d.

[0077] In step S36, the control circuit 14 determines, in the same manner as in step S24 of FIG. 7, which of the plurality of charge rate ranges Cd the charge rate is included in based on the discharge voltage Vd and the discharge current Id of the battery pack 12.

[0078] In step S37, the control circuit 14 determines the maximum power W1 that can be output from the battery pack 12 based on the charge rate range Cd and the temperature Temp of the battery pack 12, in the same manner as step S25 in FIG. 7.

[0079] In step S38, the control circuit 14 calculates the allowable power W indicating the maximum power that the CPU 21 can obtain from the battery pack 12, based on the maximum power W1 that can be output from the battery pack 12 and the internal resistance Rd of the battery pack 12, in the same manner as step S26 in FIG. 7.

[0080] In step S39, the control circuit 14 sets the allowable power W to the CPU 21. As a result, the CPU 21 ends the Pn performance state started in response to the prochot signal and is set to one of the plurality of performance states so as to obtain only power equal to or less than the allowable power W from the battery pack 12.

[0081] After the execution of step S39, the control circuit 14 returns to the discharge control process in FIG. 7.

[0082] If the internal resistance Rd is calculated to be smaller than the actual value, a value larger than the actual allowable power W will be set to the CPU 21. According to the interrupt process in FIG. 10, when there is a risk that the discharge voltage of the battery pack 12 drops and the electronic device 1 experiences an instantaneous interruption, by correcting the internal resistance Rd and recalculating the allowable power W, it is possible to accurately control the power consumption of the CPU 21 while avoiding the instantaneous interruption of the electronic device 1.

[0083] [Effects of the Embodiment, etc.] An electronic device 1 according to one aspect of the present disclosure includes a battery pack 12, a charging circuit 11 that charges the battery pack 12, a load device 20 that operates with the power of the battery pack 12, a voltage sensor 12c that detects the charging voltage and the discharging voltage of the battery pack 12, a current sensor 12b that detects the charging current and the discharging current of the battery pack 12, and a control circuit 14. The control circuit 14 calculates the internal resistance of the battery pack 12 based on the charging voltage and the charging current, and calculates an allowable power indicating the maximum power that the load device 20 can obtain from the battery pack 12 based on the discharging voltage, the discharging current, and the internal resistance, and sends a control signal to the load device 20 so that the load device 20 operates with power equal to or less than the allowable power.

[0084] In this way, by setting the allowable power of the load device 20 based on the measured internal resistance Rd of the battery pack 12, power consumption can be controlled with higher accuracy than in the past.

[0085] According to the electronic device 1 according to one aspect of the present disclosure, the control circuit 14 may control the charging circuit 11 to temporarily stop the charging of the battery pack 12 when the battery pack 12 is being charged. In this case, the control circuit 14 detects the charging voltage (first voltage) of the battery pack 12 immediately before stopping the charging of the battery pack 12. Further, the control circuit 14 detects the second voltage of the battery pack 12 after the elapse of a predetermined waiting time of 1 second or less after stopping the charging of the battery pack 12. Further, the control circuit 14 detects a first current that is the charging current immediately before stopping the charging of the battery pack 12. Further, the control circuit 14 calculates the internal resistance by dividing the potential difference between the first and second voltages by the first current. Further, after detecting the second voltage, the control circuit 14 controls the charging circuit 11 to resume the charging of the battery pack 12.

[0086] Thus, by calculating the internal resistance Ra(i) based on the potential difference between the voltage Vb immediately before stopping the charging of the battery pack 12 and the voltage Va after the elapse of a standby time of 1 second or less after stopping the charging of the battery pack 12, the internal resistance Rd of the battery pack 12 can be measured with high precision.

[0087] According to the electronic device 1 according to one aspect of the present disclosure, the control circuit 14 may obtain a plurality of internal resistances by repeating a temporary stop of charging of the battery pack 12, calculation of the internal resistance, and resumption of charging of the battery pack 12. In this case, the control circuit 14 calculates the allowable power based on the discharge voltage, the discharge current, and the average of the plurality of internal resistances.

[0088] Thus, by calculating the average of the plurality of internal resistances, the internal resistance Rd of the battery pack 12 can be measured with high precision.

[0089] According to the electronic device 1 according to one aspect of the present disclosure, the control circuit 14 may calculate a moving average of the previously calculated internal resistance and the newly calculated internal resistance. In this case, the control circuit 14 calculates the allowable power based on the discharge voltage, the discharge current, and the moving average of the internal resistance.

[0090] Thus, by calculating the moving average of the internal resistance, the internal resistance Rd of the battery pack 12 can be measured with high precision.

[0091] According to the electronic device 1 according to one aspect of the present disclosure, the electronic device 1 may further include a temperature sensor 12d that detects the temperature of the battery pack 12. In this case, the control circuit 14 corrects the internal resistance and the allowable power based on the temperature of the battery pack 12.

[0092] Thus, by correcting the internal resistance and the allowable power based on the temperature of the battery pack 12, power consumption can be controlled with high precision.

[0093] According to the electronic device 1 according to one aspect of the present disclosure, when the discharge voltage becomes smaller than a predetermined threshold value, the control circuit 14 may correct the internal resistance so as to increase the internal resistance by a predetermined correction factor greater than 1. In this case, the control circuit 14 calculates the allowable power based on the discharge voltage, the discharge current, and the corrected internal resistance.

[0094] In this way, by correcting the internal resistance Rd and recalculating the allowable power W, it is possible to accurately control the power consumption of the load device 20 while avoiding momentary interruption of the electronic device 1.

[0095] According to the electronic device 1 according to one aspect of the present disclosure, the load device 20 may include an arithmetic circuit.

[0096] Thereby, it is possible to control the power consumption of the arithmetic circuit such as the CPU 21 with higher accuracy than in the past.

[0097] According to the electronic device 1 according to one aspect of the present disclosure, the arithmetic circuit may have a plurality of performance states that operate with different powers respectively. In this case, the control circuit 14 selectively operates in one of the plurality of performance states so that the arithmetic circuit operates with power equal to or less than the allowable power according to the control signal.

[0098] Thereby, it is possible to control the power consumption of the arithmetic circuit such as the CPU 21 with higher accuracy than in the past.

[0099] A control method of the electronic device 1 according to one aspect of the present disclosure controls an electronic device including a battery pack 12 and a load device that operates with the power of the battery pack 12. This method includes a step of calculating the internal resistance of the battery pack 12 based on the charging voltage and charging current of the battery pack 12. This method includes a step of calculating an allowable power indicating the maximum power that the load device can obtain from the battery pack 12 based on the discharge voltage and discharge current of the battery pack 12 and the internal resistance. This method includes a step of controlling the load device so that the load device operates with power equal to or less than the allowable power.

[0100] Thus, by setting the allowable power of the load device 20 based on the measured internal resistance Rd of the battery pack 12, power consumption can be controlled with higher accuracy than in the prior art.

[0101] [Other Embodiments] As described above, embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited thereto, and is also applicable to embodiments in which appropriate changes, replacements, additions, omissions, etc. are made. Further, it is also possible to combine the components described in the above embodiments to form a new embodiment.

[0102] Therefore, other embodiments will be exemplified below.

[0103] The control circuit 14 is not limited to the CPU 21, and may control any arithmetic circuit having a plurality of performance states operating with different powers respectively. The arithmetic circuit may be, for example, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like.

[0104] In the example of FIG. 1, when the discharge voltage Vd becomes smaller than the threshold voltage Vmin, the charging circuit 11 generates an interrupt signal and sends it to the control circuit 14 and the CPU 21. Instead, the control circuit 14 may include a reference voltage source that generates a reference voltage representing the threshold voltage Vmin, and when the discharge voltage Vd becomes smaller than the threshold voltage Vmin, the control circuit 14 generates an interrupt signal and sends it to the CPU 21.

[0105] Depending on the specifications of each battery cell 12a, a temperature Temp and a correction coefficient k different from those shown in Fig. 6 may be used. Depending on the specifications of each battery cell 12a, a charging rate range Cd different from that shown in Fig. 8 may be used. Depending on the specifications of each battery cell 12a, a maximum power W1 having a range and number different from those shown in Fig. 9 may be used.

[0106] In the example of Fig. 6, the internal resistance Ra(i) of the battery pack 12 is corrected using a table of the temperature Temp and the correction coefficient k, but the control circuit 14 may correct the internal resistance Ra(i) using some kind of calculation formula instead of the table. In the example of Fig. 8, the charging rate range Cd is determined using a table of the discharge voltage Vd and the discharge current Id, but the control circuit 14 may calculate the charging rate range Cd using some kind of calculation formula instead of the table. In the example of Fig. 9, the maximum power W1 is determined using a table of the charging rate range Cd and the temperature Temp, but the control circuit 14 may calculate the maximum power W1 using some kind of calculation formula instead of the table.

[0107] The current sensor 12b and the voltage sensor 12c may be provided outside the battery pack 12.

[0108] If the battery pack 12 is not removable but is built into the electronic device 1, the internal resistance of the battery pack 12 may be stored in a non-volatile memory inside the control circuit 14.

[0109] As described above, the embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description have been provided.

[0110] Therefore, among the components described in the attached drawings and the detailed description, not only are there components essential for solving the problem, but there may also be components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that such non-essential components are described in the attached drawings or the detailed description should not be interpreted as immediately indicating that such non-essential components are essential.

[0111] In addition, since the above-described embodiments are for exemplifying the technology in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the equivalent scope thereof.

Industrial Applicability

[0112] According to the electronic device according to one aspect of the present disclosure, power consumption can be controlled with higher accuracy than in the past, and the usability of the electronic device can be improved.

Description of Reference Numerals

[0113] 1 Electronic device 2 AC power supply 3 AC / DC converter 11 Charging circuit 12 Battery pack 12a Battery cell 12b Current sensor 12c Voltage sensor 12d Temperature sensor 12e Non-volatile memory 13 DC / DC converter 14 Control circuit 20 Load device 21 Central processing unit (CPU) 22 Memory 23 Storage device 24 Display device 25 Input device 26 Communication interface (I / F) 31 DC / DC converter 32 Charging control circuit 33 Reference voltage source 34 Comparator SW Switch

Claims

1. A storage battery, a charging circuit for charging the storage battery, a load device operated by the power of the storage battery, a voltage sensor for detecting the charging voltage and the discharging voltage of the storage battery, a current sensor for detecting the charging current and the discharging current of the storage battery, and a control circuit, wherein the control circuit calculates the internal resistance of the storage battery based on the charging voltage and the charging current, calculates an allowable power indicating the maximum power that the load device can obtain from the storage battery based on the discharging voltage, the discharging current, and the internal resistance, sends a control signal to the load device so that the load device operates with power equal to or less than the allowable power, when the storage battery is being charged, controls the charging circuit to temporarily stop the charging of the storage battery, detects a first voltage which is the charging voltage immediately before stopping the charging of the storage battery, detects a second voltage of the storage battery after a lapse of a predetermined standby time of 1 second or less after stopping the charging of the storage battery, detects a first current which is the charging current immediately before stopping the charging of the storage battery, calculates the internal resistance by dividing the potential difference between the first and second voltages by the first current, and controls the charging circuit to resume the charging of the storage battery after the detection of the second voltage, an electronic device.

2. The control circuit calculates the state of charge of the storage battery based on the charging voltage, determines whether or not the state of charge has reached a threshold value, and when it is determined that the state of charge has reached the threshold value, controls the charging circuit to temporarily stop the charging of the storage battery. The electronic device according to Claim 1.

3. The control circuit repeatedly performs temporary stop of the charging of the storage battery, calculation of the internal resistance, and resumption of the charging of the storage battery to obtain a plurality of internal resistances, and calculates the allowable power based on the discharging voltage, the discharging current, and the average of the plurality of internal resistances. The electronic device according to Claim 1.

4. The control circuit calculates the state of charge of the storage battery based on the charging voltage, determines whether or not the state of charge has reached a threshold value corresponding to the number of repetitions, and when it is determined that the state of charge has reached the threshold value corresponding to the number of repetitions, controls the charging circuit to temporarily stop the charging of the storage battery. The electronic device according to Claim 3.

5. The control circuit calculates a moving average of the previously calculated internal resistance and the calculated internal resistance, The electronic device according to any one of claims 1 to 4, which calculates the allowable power based on the discharge voltage, the discharge current, and the moving average.

6. The control circuit calculates a weighted moving average using the previously calculated internal resistance, the weight of the previously calculated internal resistance, the calculated internal resistance, and the weight of the calculated internal resistance, The electronic device according to any one of claims 1 to 4, which calculates the allowable power based on the discharge voltage, the discharge current, and the weighted moving average.

7. The electronic device further includes a temperature sensor that detects the temperature of the storage battery, The control circuit corrects the internal resistance and the allowable power based on the temperature of the storage battery. The electronic device according to any one of claims 1 to 4.

8. When the discharge voltage becomes smaller than a predetermined threshold value, the control circuit corrects the internal resistance so as to increase the internal resistance by a predetermined correction coefficient greater than 1, The electronic device according to any one of claims 1 to 4, which calculates the allowable power based on the discharge voltage, the discharge current, and the corrected internal resistance.

9. The load device includes an arithmetic circuit. The electronic device according to any one of claims 1 to 4.

10. The arithmetic circuit has a plurality of performance states that operate with different powers respectively, The electronic device according to claim 9, wherein, according to the control signal, the arithmetic circuit selectively operates in one of the plurality of performance states so that the arithmetic circuit operates with a power equal to or less than the allowable power.

11. A control method for an electronic device including a storage battery and a load device that operates with the power of the storage battery, the method comprising: a step of calculating the internal resistance of the storage battery based on the charging voltage and charging current of the storage battery; a step of calculating an allowable power indicating the maximum power that the load device can obtain from the storage battery based on the discharge voltage and discharge current of the storage battery and the internal resistance; a step of controlling the load device so that the load device operates with a power equal to or less than the allowable power, When charging the storage battery, a step of temporarily stopping the charging of the storage battery; a step of detecting a first voltage that is the charging voltage immediately before stopping the charging of the storage battery; a step of detecting a second voltage of the storage battery after a lapse of a predetermined standby time of 1 second or less after stopping the charging of the storage battery; A step of detecting a first current which is the charging current immediately before stopping the charging of the storage battery; A step of calculating the internal resistance by dividing the potential difference between the first and second voltages by the first current; A control method for an electronic device, further including a step of restarting the charging of the storage battery after detecting the second voltage.

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