Power supply circuit, electronic device and control method

Abstract

To terminate charging more accurately in a fully charged state even when power is consumed in a system.SOLUTION: A power supply circuit supplies to a system the system power required by the system out of the DC power supplied from a power source, and charges the battery with the remaining power, which is charging power. When the cell voltage of the battery is a predetermined detection voltage or higher and the charging current of the charging power is a predetermined detection current or less, the power supply circuit determines that the battery is fully charged, estimates the cell voltage at the time when the battery is determined to be fully charged on the basis of the cell voltage obtained under a specific charging state of the battery as a second detection voltage, and updates the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power supply circuit, an electronic device and a control method, for example, for charging a battery. [Background technology]

[0002] Battery packs are often found in information devices such as personal computers (PCs), tablet computers, smartphones, and various other electronic devices. Even when power is not supplied from an external source, these electronic devices can operate by consuming the power stored in the battery pack. The battery pack charges the battery (secondary battery) from an alternating current (AC) adapter under the control of a power supply circuit, such as a system charging integrated circuit (IC).

[0003] For example, the charging method described in Patent Document 1 is a method for charging a secondary battery using a constant voltage power supply with limited current, in which the secondary battery is further charged for a certain period of time after a predetermined condition is not met. The predetermined condition is that the battery voltage of the secondary battery reaches a predetermined voltage, or that the charging current of the secondary battery reaches a predetermined current.

[0004] There are two charging methods from the system to the battery: system off charge (also called off charge) and system operation charge (also called on charge). System off charge is a method that charges only the battery without supplying power to the system. System operation charge is a method that charges the battery while supplying power to the system. In system off charge, the supply current I supplied from the AC adapter is totalThe controller determines that the battery has reached a fully charged state and terminates charging when the conditions are met: the cell voltage generated in the battery is equal to or greater than a predetermined detection voltage (also called taper voltage) and the charging current is equal to or less than a predetermined detection current (also called taper current). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-183232 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in system operation charging, the supplied charging current I total The required current is the system current I sys The battery is supplied with a supply current I total The system current I supplied to the system from sys is removed, and the remaining current I total -I sys As a result, the current supplied may not meet the battery's requirements. In particular, when using an AC adapter with a low rated power, the decrease in charging power to the battery may be significant. Under such circumstances, even if the conditions are met where the cell voltage is equal to or greater than the taper voltage and the charging current is equal to or less than the taper current, the amount of charge stored in the battery may be smaller than the expected capacity in a fully charged state (full charge capacity).

[0007] One possible reason is that the taper voltage is set to a voltage that is a certain margin lower than the rated system voltage supplied by the system. If the charging current falls below the taper current and the full charge is determined based on the fixed taper voltage, the charge capacity stored in the battery may be lower than the full charge capacity. The taper voltage depends on the circuit resistance values ​​of the battery and system, but these circuit resistance values ​​vary from one device to another. To ensure safety or stability, a larger margin than necessary is often set for each device during the design phase, taking into account individual differences. [Means for solving the problem]

[0008] The present application has been made to solve the above-mentioned problems, and a power supply circuit according to one aspect of the present application supplies a system with system power required by the system from among the DC power supplied from a power source, charges a battery with the remaining power, which is charging power, and determines that the battery is fully charged when the cell voltage of the battery is equal to or higher than a predetermined detection voltage and the charging current of the charging power is equal to or lower than a predetermined detection current, and estimates the cell voltage at the time when the battery is determined to be fully charged based on the cell voltage obtained under a specific charging state of the battery as a second detection voltage, and updates the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage.

[0009] The power supply circuit may define, as the second detection voltage, the cell voltage at a time when the state of charge is determined to be fully charged when the charging power is charged to the battery without supplying the system power to the system.

[0010] When the charging method for the battery is changed from a first charging mode in which charging is performed at a constant charging current to a second charging mode in which charging is performed at a constant charging voltage, the power supply circuit may measure a circuit resistance value from the power supply circuit to the battery based on the charging voltage to the battery, the cell voltage, and the charging current, and may determine the voltage dropped from the charging voltage due to the circuit resistance value and the detection current as the second detection voltage.

[0011] The power supply circuit may change the predetermined detection voltage to the first detection voltage when the charging state is not determined to be fully charged even when the charging time of the battery exceeds a predetermined reference charging time.

[0012] The power supply circuit may include the battery.

[0013] An electronic device according to a second aspect of the present application may include the power supply circuit described above.

[0014] A control method according to a third aspect of the present application is a control method for a power supply circuit that supplies a system with system power required by the system from the DC power supplied from a power source, charges a battery with the remaining power, which is charging power, and determines that the battery is fully charged when the cell voltage of the battery is equal to or higher than a predetermined detection voltage and the charging current of the charging power is equal to or lower than a predetermined detection current, wherein the power supply circuit estimates the cell voltage at the time when the battery is determined to be fully charged based on the cell voltage obtained under a specific charging state of the battery as a second detection voltage, and updates the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage. [Effects of the Invention]

[0015] According to the embodiment of the present application, charging can be terminated more accurately in a fully charged state even when power is consumed in the system. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic block diagram illustrating an example of a hardware configuration of an electronic device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic block diagram showing an example of a circuit arrangement according to the present embodiment. [Figure 3] FIG. 10 is a diagram showing a first example of the cell voltage and charging current over time during charging. [Figure 4]FIG. 10 is a diagram showing a second example of the cell voltage, charging voltage, and charging current over time during charging. [Figure 5] 4 is a flowchart illustrating a charge control process according to the present embodiment. [Figure 6] 5 is a flowchart showing a first example of a detection voltage setting process according to the present embodiment. [Figure 7] 10 is a flowchart showing a second example of the detection voltage setting process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present application will be described with reference to the drawings. First, an overview of an electronic device 1 according to an embodiment of the present application will be described. The electronic device 1 includes a power supply circuit 33. The power supply circuit 33 supplies the system with the system power required for the system from the DC power supplied from the DC power source, and charges the battery with the remaining charging power. The power supply circuit 33 determines that the battery is fully charged when the cell voltage of the battery is equal to or higher than a predetermined taper voltage and the charging current of the charging power is equal to or lower than a predetermined detection current. In this embodiment, the taper voltage is not a fixed value but a variable value. Here, when the battery charging conditions satisfy specific charging conditions, the power supply circuit 33 estimates the taper voltage at full charge as a second taper voltage based on the cell voltage. The power supply circuit 33 updates the predetermined taper voltage from a predetermined first taper voltage to the second taper voltage.

[0018] The electronic device 1 according to this embodiment typically has a size and weight that are convenient for portability and can be an electronic device that consumes power stored in a battery. The electronic device 1 may be any type of information device, such as a PC, a smartphone, or a tablet terminal. The electronic device 1 may also be any device, such as a measuring instrument or a monitoring device, that is installed in an environment where it is difficult to constantly supply power from a DC power source. In the following description, the electronic device 1 is mainly a personal computer (PC). In addition, in this application, the term "system" may refer to a device, i.e., a load, of the electronic device 1 that consumes power supplied from the power supply circuit 33. When the electronic device 1 is an information device, the power consumption of its computer system (also called a host system) usually accounts for the majority of the processing of the electronic device 1.

[0019] 1 is a schematic block diagram showing an example of the hardware configuration of an electronic device 1 according to this embodiment. The electronic device 1 includes a CPU 11, a main memory 12, a video subsystem 13, a display 14, a PCH (Platform Controller Hub) 21, a BIOS (Basic Input Output System) memory 22, an auxiliary storage device 23, a WLAN (Wireless Local Area Network) card 25, a USB (Universal Serial Bus) connector 26, an EC (Embedded Controller) 31, an input unit 32, a power supply circuit 33, a battery pack 34, and a power button 38.

[0020] The CPU 11 is a processor that forms the core of a system device provided in the electronic device 1. The CPU 11 is a processor that executes various arithmetic processes instructed by commands written in software (programs). The CPU 11 executes processes instructed by various software, such as an OS (Operating System), a BIOS, and an application program (referred to as an "app" or "application" in this application). Note that executing processes instructed by commands written in software is sometimes referred to as "executing software."

[0021] The main memory 12 is a writable memory used as a read area for the processor's executable programs or as a work area for writing processing data for the executable programs. The main memory 12 is composed of, for example, multiple DRAM (Dynamic Random Access Memory) chips. The executable programs include an OS, various drivers for operating hardware such as peripheral devices, various services / utilities, applications, etc.

[0022] The CPU 11 and main memory 12 function as a system device that constitutes the core computer system, i.e., the host system, of the electronic device 1. The computer system of the electronic device 1 is configured to include a system device as hardware, and software such as an OS, schedules, and tasks.

[0023] Video subsystem 13 performs image processing under the control of CPU 11. Video subsystem 13 includes a video controller and a video memory (not shown). The video controller performs image processing in accordance with drawing commands input from CPU 11, generates drawing information, and writes the generated drawing information to video memory (not shown). The video controller reads the drawing information from the video memory and outputs display data indicating the read drawing information to display 14 (image processing). On the other hand, the CPU 11 executes a graphics driver on the OS to control the operation of the video subsystem 13. The CPU 11 outputs drawing commands to the video subsystem 13 from the OS, applications, and other programs to realize image processing.

[0024] The display 14 displays a display screen based on the display data output from the CPU 11. The display 14 may be, for example, a liquid crystal display (LCD) or an organic light emitting diode (OLED) display.

[0025] The PCH 21 includes one or more controllers and can be connected to multiple devices to input and output various types of data. The PCH 21 is, for example, one or a combination of bus controllers such as USB, Serial Advanced Technology Attachment (Serial ATA), Serial Peripheral Interface (SPI) bus, Peripheral Component Interconnect (PCI) bus, PCI-Express bus, and Low Pin Count (LPC) bus. The multiple devices to which the PCH 21 can be connected include, for example, a BIOS memory 22, an auxiliary storage device 23, a WLAN card 25, a USB connector 26, and the EC 31, which will be described later.

[0026] The BIOS memory 22 is composed of electrically rewritable nonvolatile memory. Examples of such nonvolatile memory include EEPROM (Electrically Erasable Programmable Read Only Memory) and flash ROM (Read Only Memory). The BIOS memory 22 stores firmware for controlling the operation of the BIOS, the EC31, and other devices. The BIOS is firmware for performing basic input and output of system devices. In this application, firmware defined in accordance with the specifications defined in the UEFI (Unified Extensible Firmware Interface) may also be included in the concept of BIOS.

[0027] The auxiliary storage device 23 persistently stores various types of data. The stored data includes various programs that can be executed by the CPU 11 or other devices, parameters, data used in various processes, and data acquired by various processes. The auxiliary storage device 23 may be, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The auxiliary storage device 23 is configured to include various types of nonvolatile memory. For example, a flash memory is used as the nonvolatile memory. The various programs may include, for example, any one or a combination of an OS, a driver, firmware, an application, and the like.

[0028] The WLAN card 25 connects to a wireless LAN or to another network via a wireless LAN, enabling transmission and reception of various types of data between the connected device and the network. The USB connector 26 is a connector for connecting various peripheral devices using USB.

[0029] The EC 31 is a one-chip microcomputer that monitors and controls the status of various devices (peripheral devices, sensors, etc.) regardless of the operating state of the host system that is the core of the electronic device 1. The EC 31 includes a CPU separate from the CPU 11, a RAM separate from the main memory 12, a ROM, a multi-channel A / D (Analog-to-Digital) input terminal, a D / A (Digital-to-Analog) output terminal, a timer, and digital input / output terminals (not shown). The digital input / output terminals of the EC 31 are connected to an input unit 32, a power supply circuit 33, etc., and the EC 31 is capable of controlling the operations of these devices. The EC 31 monitors the operating status of each device constituting the electronic device 1 and determines the amount of power required for operation (sometimes referred to herein as "device power") for each device so that it exceeds the power consumption of that device. The total of the device powers corresponds to the system power. The devices to be monitored include the system devices of the electronic device 1, mainly the CPU 11. The EC 31 outputs a system power request indicating the device power of each device to the power supply circuit 33. As will be described later, power equivalent to the device power is supplied from the power supply circuit 33 to each device constituting the system.

[0030] The input unit 32 includes an input device that detects a user operation and outputs an operation signal corresponding to the detected operation to the EC 31. Examples of the input unit 32 include a keyboard and a touchpad. The touch sensor that constitutes the input unit 32 may overlap the display 14 that constitutes the display unit and be configured as a touch panel.

[0031] The power supply circuit 33 receives DC power from an AC (Alternating Current) adapter 37. The power supply circuit 33 supplies the system with the system power required by the system out of the supplied DC power under the control of the EC 31. The power supply circuit 33 supplies power to each device corresponding to the device power specified for each device in the system power request notified by the EC 31. The power supply circuit 33 supplies power equivalent to the system power to the entire system of the electronic device 1. The power supply circuit 33 charges the remaining power, excluding the system power, from the supplied DC power to the battery pack 34 as charging power.

[0032] The power supply circuit 33 includes a charging circuit 332 (FIG. 2) and a converter (not shown). The charging circuit 332 charges the battery pack 34 with charging power according to the charging state of the battery pack 34. The charging circuit 332 determines that the charging state of the battery pack 34 is fully charged when the cell voltage of the battery pack 34 is equal to or higher than a predetermined taper voltage and the charging current of the charging power is equal to or lower than a predetermined taper current. In this application, determining whether the charging state has reached a fully charged state or the result of this determination may be referred to as a "full charge determination." When the charging circuit 332 determines that the battery pack 34 is fully charged, it stops charging the battery pack 34.

[0033] The converter converts the voltage of the power supplied to itself from the AC adapter 37 into the voltage required by each device. The converter supplies the converted voltage power to the device that requires the converted voltage power.

[0034] The battery pack 34 includes one or more batteries (also called secondary batteries, cells, etc.) and a measurement circuit 342 (not shown). The measurement circuit 342 measures the charging voltage and charging current as the charging state of the battery, and notifies the power supply circuit 33 of charging state information indicating the measured charging voltage and charging current. The battery stores charging power supplied from the power supply circuit 33.

[0035] The AC adapter 37 converts AC power supplied from an external power source into DC power with a constant voltage, and supplies the converted power to the power supply circuit 33. The AC adapter 37 is connected to the power supply circuit 33 so as to be able to input and output control signals. The AC adapter 37 has an attachment that allows it to be attached and detached to the housing of the electronic device 1 including the power supply circuit 33. The AC adapter 37 may be physically connected to the USB connector 26 so as to be detachable.

[0036] The power button 38 controls whether or not power is supplied to the entire electronic device 1 (Power ON / OFF) each time a press operation is received. The power button 38 outputs a press signal indicating that the button has been pressed to the EC 31. When a press signal is input from the power button 38 while the electronic device 1 is powered off (no power is being supplied), the EC 31 causes the power supply circuit 33 to start supplying power to each device of the electronic device 1 (power on). When a press signal is input from the power button 38 while the electronic device 1 is energized (power is being supplied), the EC 31 causes the power supply circuit 33 to stop supplying power to each device of the electronic device 1 (power off).

[0037] Next, an example of a circuit configuration according to this embodiment will be described below: Fig. 2 is a schematic block diagram showing an example of a circuit layout according to this embodiment. The power supply circuit 33 includes a charging circuit 332 and FETs 334a, 334b, and 334c. The battery pack 34 includes a measuring circuit 342, FETs 344a and 344b, a fuse 346, and cells CL01 and CL02. The power line is electrically connected from the AC adapter 37 to the positive terminal of cell CL01 via FETs 334a, 334b, 334c, 344a, and 344b and fuse 346. Cells CL01 and CL02 are connected in series. The negative terminal of cell CL02 is grounded (GND) via a resistive element R. This prevents or reduces damage to cells CL01 and CL02 caused by reverse connection of cells CL01 and CL02 or the application of unexpected voltage to the negative terminal.

[0038] FET (Field Effect Transistor) 334a prevents reverse current flow from branch point 336 to AC adapter 37. FET 334b ​​adjusts the current from AC adapter 37 to branch point 336 under the control of charging circuit 332. FET 334c switches between conduction and non-conduction between branch point 336 and battery pack 34 under the control of charging circuit 332. FET 344a controls the current discharged from cells CL01 and CL02 under the control of measurement circuit 342. FET 344b controls the current charged to cells CL01 and CL02 under the control of measurement circuit 342.

[0039] The source electrode (hereinafter may be referred to as the "S electrode"), drain electrode (hereinafter may be referred to as the "D electrode"), and gate electrode (hereinafter may be referred to as the "G electrode") of FET 334a are electrically connected to the AC adapter 37, the D electrode of FET 334b, and the charging circuit 332, respectively. FET 334a can prevent reverse current from flowing from FET 334b ​​to the AC adapter 37 by maintaining the voltage applied to the G electrode so that it does not become significantly higher than 0V.

[0040] The S electrode, D electrode, and G electrode of FET 334b ​​are electrically connected to branch point 336, the D electrode of FET 334a, and charging circuit 332, respectively. By increasing the positive potential applied to the G electrode, the current flowing in from AC adapter 37 can be increased.

[0041] The S electrode, D electrode, and G electrode of the FET 334c are electrically connected to the battery pack 34, the branch point 336, and the charging circuit 332, respectively. The FET 334c controls whether or not conduction (ON / OFF) from the branch point 336 to the battery pack 34 is established by applying an open / close control signal to the G electrode from the charging circuit 332. The open / close control signal is a binary signal that can assume two potential levels. The lower of the two potential levels is called low potential (L), and the higher is called high potential (H). The low potential is, for example, a potential within a predetermined range from 0 V. The high potential is a positive potential significantly higher than the low potential. When charging the battery pack 34, the charging circuit 332 applies an open / close control signal having a high potential to the G electrode of the FET 334c, and when not charging, stops applying the open / close control signal having a high potential to the G electrode of the FET 334c.

[0042] The branch point 336 supplies system power, which is a part of the DC power supplied from the AC adapter 37, to the system, and supplies the remaining charging power to the battery pack 34 via the FET 334c. The total current value I total is the system current I sys and the charging current I bat It is equivalent to the sum of

[0043] The S electrode, D electrode, and G electrode of FET 344a are electrically connected to the power supply circuit 33, the D electrode of FET 344b, and the measurement circuit 342, respectively. FET 344a can increase the current of power discharged from cell CL01 by increasing the positive potential applied to the G electrode. The S electrode, D electrode, and G electrode of FET 344b are electrically connected to fuse 346, the D electrode of FET 344a, and measurement circuit 342, respectively. FET 344b can increase the current of power charged from power supply circuit 33 to cells CL01 and CL02 by increasing the positive potential applied to the G electrode.

[0044] The S electrode, D electrode, and G electrode of FET 334b ​​are electrically connected to branch point 336, the D electrode of FET 334a, and charging circuit 332, respectively. By increasing the positive potential applied to the G electrode, the current flowing in from AC adapter 37 can be increased. When fuse 346 detects a current exceeding a predetermined limit, it shuts off the current flowing through it, thereby preventing excessive current from flowing into or out of cells CL01 and CL02.

[0045] The charging circuit 332 and the measuring circuit 342 are each connected to the EC31 using signal lines. The signal lines include a data signal line (DAT) and a clock signal line (CLK). The data signal line is used to transmit control signals and other data. The clock signal line is used to transmit clock signals. The charging circuit 332 and the measuring circuit 342 are each synchronized with the EC31 using the clock signal input from the EC31. For example, a system management bus (SMB) is used as the signal line.

[0046] Charging circuit 332 receives charging state information from measuring circuit 342 via EC31. Charging circuit 332 controls charging of battery pack 34 based on the charging state indicated by the charging state information. Charging circuit 332 implements constant current (CC) charging and constant voltage (CV) charging as its main charging methods. CC charging refers to a charging mode in which charging is performed at a preset constant charging current value. CC charging enables charging at a relatively large current, and as charge accumulates in the cells of battery pack 34, the electromotive force increases and the resistance decreases. CC charging is performed by controlling the charging voltage V charge This may occur before a certain charging voltage value has been reached.

[0047] CV charging refers to a charging mode in which a battery is charged at a preset constant charging voltage. charge is the predetermined charging voltage V charge,CV The charge voltage Vcharge is a constant value V charge,CV At this stage, the internal cell voltage V cell is the charging voltage V charge In CV charging, the cell voltage V cell Charging voltage V charge As the battery approaches full charge, the charging current decreases. Full charge determination can be made during CV charging.

[0048] The charging circuit 332 detects the cell voltage V of the battery pack 34. cell is equal to or greater than a predetermined taper voltage, and the charging current I bat is the predetermined taper current I tp When the charging circuit 332 determines that the battery pack 34 is fully charged, the charging circuit 332 stops charging the battery pack 34. The first taper voltage V tp,1 is preset in the charging circuit 332. In the example of FIG. 4, the first taper voltage V tp,1 For example, the charging voltage V charge,CV A design value of a voltage lower than the reference voltage by a predetermined minute margin voltage (for example, 50 to 200 mV) ΔV can be used.

[0049] When the charging conditions for the battery pack 34 satisfy a specific charging condition, the charging circuit 332 detects the cell voltage V cell Based on this, the taper voltage at full charge is calculated as the second taper voltage V tp,2 The power supply circuit 33 estimates the first taper voltage V as the predetermined taper voltage used for full charge determination. tp,1 The second taper voltage V estimated from tp,2 If the battery pack 34 does not reach a fully charged state even when the total charging time for the battery pack 34 exceeds a predetermined reference charging time (for example, 8 to 20 hours), the power supply circuit 33 updates the predetermined taper voltage to the second taper voltage V tp,2 to the first taper voltage V tp,1 Change to the second taper voltage V tp,2The method for estimating this will be described later. The charging circuit 332 is, for example, a system charger IC.

[0050] The measurement circuit 342 is a circuit for measuring the state of charge of the cells CL01 and CL02. The measurement circuit 342 converts the potential at the positive electrode of the cell CL01 into a cell voltage V cell and the current flowing from the power supply circuit 33 is measured as the charging current I bat The measurement circuit measures the cell voltage V cell and charging current I bat The measuring circuit 342 outputs charging state information indicating the charging state to the charging circuit 332 via the EC 31. The charging circuit 332 controls charging based on the charging state indicated in the charging state information input from the measuring circuit 342.

[0051] The measurement circuit 342 controls the discharge from the cell CL01 and the charge to the cell CL02 by adjusting the potentials applied to the G electrodes of the FETs 344a and 344b. The measurement circuit 342 is, for example, a battery fuel gauge IC (Battery Fuel Gauge Integrated Circuit). When power is not supplied from the AC adapter 37, the EC 31 outputs a system current I sys and the system current I sys A current equivalent to

[0052] Next, the second taper voltage V tp,2 The first example of the estimation method is the cell voltage V cell The second taper voltage V tp,2 The charging circuit 332 can determine that the charging method is system non-operation charging, that is, charging in a state where no power is supplied to the system, by checking whether the system power request notified from the EC 31 indicates zero or whether the system power is unnecessary. The charging circuit 332 receives the cell voltage V cellThe charging circuit 332 notifies the first taper voltage V tp,1 Instead, the newly defined second taper voltage V tp,2 is used to determine whether the battery is fully charged.

[0053] In the example in Figure 3, the cell voltage V cell is the first taper voltage V tp,1 Even after exceeding the charging current I bat is the taper current I tp When the charge current exceeds I, it decreases over time. Therefore, the full charge is not immediately determined. During on-charge, the charge current I bat decreases, and the taper current I tp The first taper voltage V tp,1 When the above formula is used, the states of the cells CL01 and CL02 are erroneously determined to be fully charged even though the cells CL01 and CL02 have not yet reached the fully charged state. However, the second taper voltage V tp,2 By using bat is the taper current I tp Even if the cell voltage V cell is the second taper voltage V tp,2 Since the second taper voltage V has not yet been reached, full charge is not immediately determined. tp,2 cell voltage V cell By comparing the actual cell voltage V cell The second taper voltage V tp,2 By adopting this method, individual differences can be eliminated.

[0054] The second example of the estimation method is to estimate the circuit resistance in the path from the power supply circuit 33 to the cell CL01 and the predetermined taper current I when the charging mode is changed from CC charging to CV charging. tp Voltage drop V based on dp This ensures a constant charging voltage V charge,CV The voltage dropped from the second taper voltage V tp,2In the example of Figure 4, the charging mode is charge is a predetermined constant charging voltage V charge,CV When the voltage at the node 336 reaches the charging voltage V, the charging is changed from CC to CV. charge The EC31 is measured as the charging voltage V charge is a constant charging voltage V charge,CV When it is determined that the charging voltage V has reached the predetermined value, the charging circuit 332 issues a command to change the charging mode from CC charging to CV charging. When the charging mode change command is input from the EC 31, the charging circuit 332 changes the charging mode from CC charging to CV charging. The charging circuit 332 determines that the charging voltage V charge,CV to cell voltage V cell Voltage drop to V dp (=V charge,CV -V cell ) is the charging current I bat Divide by the circuit resistance R cir In the example of FIG. 2, the circuit resistance R cir is generated by FETs 334c, 344a, and 344b and fuse 346. The charging circuit 332 generates a charging voltage V charge,CV from the circuit resistance R cir The taper current I tp Voltage drop due to R cir ×I tp Subtracting this, the second taper voltage V tp,2 can be determined.

[0055] Next, an example of the charge control process according to this embodiment will be described. FIG. 5 is a flowchart illustrating the charge control process according to this embodiment. The process of FIG. 5 is executed while the battery pack 34 is being charged. (Step S102) The charging circuit 332 detects the cell voltage V cell The cell voltage V cell is the taper voltage V that is set at that time. tp In this embodiment, it is determined whether the taper voltage V tpis the first taper voltage V tp,1 and the second taper voltage V tp,2 The cell voltage V cell is the taper voltage V tp If it is determined that the taper voltage V is equal to or greater than the predetermined value (YES in step S102), the process proceeds to step S104. tp If it is determined that the difference is less than the predetermined value (NO in step S102), the process in step S102 is repeated.

[0056] (Step S104) The charging circuit 332 supplies a charging current I bat is the predetermined taper current I tp Determine whether the taper current I tp If it is determined that the taper current I is equal to or less than the predetermined value (YES in step S104), the process proceeds to step S106. tp If it is determined that the difference exceeds the threshold (NO in step S104), the process returns to step S102. (Step S106) The charging circuit 332 determines that the battery pack 34 is fully charged and stops charging the battery pack 34. At this time, the charging circuit 332 stops applying the high potential (H) open / close control signal to the G electrode of the FET 334c and cuts off the charging power. Thereafter, the processing of FIG. 5 ends.

[0057] Next, an example of the taper voltage setting process according to this embodiment will be described. tp As the initial value of the first taper voltage V tp,1 is set in advance in the charging circuit 332. FIG. 6 is a flowchart showing a first example of the taper voltage setting process according to this embodiment. (Step S202) The charging circuit 332 determines whether the charging state at that time is off-charge. For example, the charging circuit 332 determines whether the charging current I batis a positive value significantly greater than 0 A and no system power is required by the system power request notified from the EC 31, it can be determined that the system is off-charge, and otherwise it can be determined that the system is not off-charge. If it is determined that the system is off-charge (YES in step S202), the process proceeds to step S204. If it is determined that the system is not off-charge (NO in step S202), the process of step S202 is repeated without changing the taper voltage.

[0058] (Step S204) The charging circuit 332 generates the first taper voltage V tp,1 and the preset taper current I tp The full charge determination is performed using the above formula (FIG. 5). If it is determined that the state of charge of the battery pack 34 is fully charged (YES in step S204), the process proceeds to step S206. If it is determined that the state of charge has not yet reached the full charge state (NO in step S204), the taper voltage is not changed and the process returns to step S202.

[0059] (Step S206) The measurement circuit 342 measures the cell voltage V cell and notifies the charging circuit 332. (Step S208) The charging circuit 332 detects the cell voltage V cell The second taper voltage V tp,2 The taper voltage V is used to determine full charge. tp The first taper voltage V tp,1 to the second taper voltage V tp,2 Change to. (Step S210) The charging circuit 332 determines whether the total charging time from the start of charging will reach a fully charged state within a certain time. If it is determined that the fully charged state will not be reached even after the certain time has elapsed (YES in step S210), the taper voltage V tp The first taper voltage V tp,1 If it is determined that the battery is fully charged (NO in step S210), the second taper voltage V tp,2 is not changed, and the process of step S210 is repeated.

[0060] FIG. 7 is a flowchart showing a second example of the taper voltage setting process according to this embodiment. (Step S302) The charging circuit 332 determines whether the charging state at that time is charging. For example, the charging circuit 332 determines whether the charging current I bat is a positive value significantly greater than 0 A, it is determined that charging is in progress, and in other cases, it can be determined that charging is not in progress. If it is determined that charging is in progress (YES in step S302), the process proceeds to step S304. If it is determined that charging is not in progress (NO in step S302), the first taper voltage V tp,1 The process of step S302 is repeated without changing the value of the parameter.

[0061] (Step S304) The charging circuit 332 monitors whether or not a charge mode change instruction has been input from the EC 31, and determines whether or not the charge mode has changed from CC charge to CV charge. If it is determined that the charge mode has changed to CV charge (YES in step S304), the process proceeds to step S306. If it is determined that the charge mode has not changed to CV charge (NO in step S304), the first taper voltage V tp,1 Without changing the value, the process returns to step S302.

[0062] (Step S306) The charging circuit 332 detects the charging voltage V charge and cell voltage V cell potential difference and charging current I bat from the circuit resistance R cir Here, the measurement circuit 342 calculates the cell voltage V cell and notifies the charging circuit 332. The charging circuit 332 measures the charging voltage V charge and charging current I bat Measure. (Step S308) The charging circuit 332 is cir Based on the taper current I tp Voltage drop due to R cir ×I tp Charging voltage V charge Subtract from this to get the second taper voltage V tp,2 Calculate the taper voltage V used to determine full charge.tp The first taper voltage V tp,1 to the second taper voltage V tp,2 Change to. (Step S310) The charging circuit 332 determines whether the total charging time will reach a fully charged state within a certain time. If it is determined that the fully charged state will not be reached even after the certain time has elapsed (YES in step S310), the taper voltage V tp The first taper voltage Vt p,1 If it is determined that the battery is fully charged (NO in step S310), the second taper voltage V tp,2 is not changed, and the process of step S310 is repeated.

[0063] As described above, the power supply circuit 33 according to this embodiment supplies the system with the system power required by the system from the DC power supplied from the power source, charges a battery (e.g., battery pack 34) with the remaining power, i.e., charging power, and determines that the battery is fully charged when the cell voltage of the battery is equal to or higher than a predetermined detection voltage (i.e., taper voltage) and the charging current of the charging power is equal to or lower than a predetermined detection current (i.e., taper current). The power supply circuit 33 estimates the cell voltage at the time when the battery is determined to be fully charged based on the cell voltage obtained under specific charging conditions, as a second detection voltage (e.g., second taper voltage), and updates the predetermined detection voltage from a predetermined first detection voltage (e.g., first taper voltage) to the second detection voltage. With this configuration, the cell voltage at full charge estimated based on the cell voltage of the battery when specific charging conditions are met is set as the detection voltage for determining whether the battery has reached full charge. Therefore, even if the charging current temporarily drops due to power consumption in the system, it is possible to avoid erroneous determination that the battery is fully charged if the measured cell voltage does not reach the cell voltage at full charge. This makes it possible to more reliably continue charging the battery until it reaches full charge. Furthermore, because the second detection voltage is estimated from the cell voltage based on the actually detected charging conditions, it is possible to detect a full charge state that is appropriate for each individual battery's electrical characteristics, regardless of individual differences.

[0064] The power supply circuit may determine, as the second detection voltage, the cell voltage at the time when the charging state is determined to be fully charged when charging the battery with charging power without supplying system power to the system. This configuration prevents temporary charging current due to power consumption in the system from being increased, and the cell voltage at that point is used as the second detection voltage to determine the full charge state. Therefore, even if the charging current temporarily drops, false detection of the full charge state can be avoided as long as the cell voltage does not exceed the second detection voltage.

[0065] When the charging method for the battery is changed from a first charging mode (CC charging) at a constant charging current to a second charging mode (CV charging) in which charging is performed at a constant charging voltage, the power supply circuit may measure the circuit resistance value from the power supply circuit to the battery based on the charging voltage, cell voltage, and charging current to the battery, and determine the voltage dropped from the charging voltage due to the circuit resistance value and the detected current as the second detected voltage. With this configuration, the voltage drop in the fully charged state, and therefore the cell voltage, is estimated as the second detection voltage based on the circuit resistance determined from the voltage drop from the charging voltage to the cell voltage when the charging mode is changed and the detection current, so that even if the charging current temporarily drops, erroneous detection of the fully charged state can be avoided as long as the cell voltage does not exceed the second detection voltage.

[0066] The power supply circuit may change the predetermined detection voltage to the first detection voltage when the charging state of the battery is not determined to be fully charged even when the charging time of the battery exceeds a predetermined reference charging time. With this configuration, if the full charge state is not detected using the second detection voltage even after a long charging time, the second detection voltage is canceled and the first detection voltage is used to determine the full charge state, thereby eliminating the second detection voltage that cannot be detected even when the full charge state is reached.

[0067] The power supply circuit 33 may include a battery pack 34 and may be configured as a single power supply circuit 33. The number of cells included in the battery pack 34 is not limited to two, but may be one, or three or more. When the battery pack 34 includes multiple cells, some or all of the cells may be connected in parallel.

[0068] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to the above-described embodiments, and the present invention also includes designs that do not deviate from the gist of the present invention. The configurations described in the above-described embodiments can be combined in any manner. [Explanation of symbols]

[0069] 1...electronic device, 11...CPU, 12...main memory, 13...video subsystem, 14...display, 21...PCH, 22...BIOS memory, 23...auxiliary storage device, 25...WLAN card, 26...USB connector, 31...EC, 32...input section, 33...power supply circuit, 34...battery pack, 37...AC adapter, 38...power button, 332...charging circuit, FET334a, 334b, 334c...FET, 342...measuring circuit, 344a, 344b...FET, 346...fuse, CL01, CL02...cell, R...resistive element

Claims

1. Among the DC power supplied from the power source, a system power required by the system is supplied to the system, and the remaining power, i.e., charging power, is charged to the battery; a power supply circuit that determines a state of charge of the battery as fully charged when a cell voltage of the battery is equal to or higher than a predetermined detection voltage and a charging current of the charging power is equal to or lower than a predetermined detection current, estimating, as a second detected voltage, the cell voltage at a time when the state of charge is determined to be fully charged based on the cell voltage obtained under a specific state of charge of the battery; updating the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage; When the charging method for the battery is changed from a first charging mode in which charging is performed at a constant charging current to a second charging mode in which charging is performed at a constant charging voltage, measuring a circuit resistance value from the power supply circuit to the battery based on a charging voltage to the battery, the cell voltage, and the charging current; The voltage dropped from the charging voltage due to the circuit resistance and the detection current is defined as the second detection voltage. power circuit.

2. Among the DC power supplied from the power source, a system power required by the system is supplied to the system, and the remaining power, i.e., charging power, is charged to the battery; a power supply circuit that determines a state of charge of the battery as fully charged when a cell voltage of the battery is equal to or higher than a predetermined detection voltage and a charging current of the charging power is equal to or lower than a predetermined detection current, estimating, as a second detected voltage, the cell voltage at a time when the state of charge is determined to be fully charged based on the cell voltage obtained under a specific state of charge of the battery; updating the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage; When the charging time of the battery exceeds a predetermined reference charging time but the charging state is not determined to be fully charged, the predetermined detection voltage is changed to the first detection voltage. power circuit.

3. When the charging power is charged to the battery without supplying the system power to the system, the cell voltage at the time when the state of charge is determined to be fully charged is defined as the second detection voltage.

3. The power supply circuit according to claim 1.

4. The battery 3. The power supply circuit according to claim 1.

5. A power supply circuit according to claim 1 or 2 is provided. electronic equipment.

6. Among the DC power supplied from the power source, a system power required by the system is supplied to the system, and the remaining power, i.e., charging power, is charged to the battery; A control method for a power supply circuit, which determines that the state of charge of the battery is fully charged when a cell voltage of the battery is equal to or higher than a predetermined detection voltage and a charging current of the charging power is equal to or lower than a predetermined detection current, The power supply circuit includes: estimating, as a second detected voltage, the cell voltage at a time when the state of charge is determined to be fully charged based on the cell voltage obtained under a specific state of charge of the battery; updating the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage; When the charging method for the battery is changed from a first charging mode in which charging is performed at a constant charging current to a second charging mode in which charging is performed at a constant charging voltage, measuring a circuit resistance value from the power supply circuit to the battery based on a charging voltage to the battery, the cell voltage, and the charging current; The voltage dropped from the charging voltage due to the circuit resistance and the detection current is defined as the second detection voltage. Control method.

7. Among the DC power supplied from the power source, a system power required by the system is supplied to the system, and the remaining power, i.e., charging power, is charged to the battery; A control method for a power supply circuit, which determines that the state of charge of the battery is fully charged when a cell voltage of the battery is equal to or higher than a predetermined detection voltage and a charging current of the charging power is equal to or lower than a predetermined detection current, The power supply circuit includes: estimating, as a second detected voltage, the cell voltage at a time when the state of charge is determined to be fully charged based on the cell voltage obtained under a specific state of charge of the battery; updating the predetermined detection voltage from a predetermined first detection voltage to the second detection voltage; When the charging time of the battery exceeds a predetermined reference charging time but the charging state is not determined to be fully charged, the predetermined detection voltage is changed to the first detection voltage. power circuit.

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