Power supply system, method, chip and terminal device for terminal equipment

Abstract

The present application provides a power supply system, method, chip and terminal device for a terminal device, which relates to the field of charging. The power supply system includes: a battery pack, a bypass circuit, a buck circuit and a controller; the battery pack includes at least two batteries; the output end of the battery pack is connected to the input end of the buck circuit, and the output end of the buck circuit is connected to the power-consuming element of the terminal device; one end of the bypass circuit is connected to the input end of the buck circuit, and the other end of the bypass circuit is connected to the output end of the buck circuit; the controller is used to control the buck circuit to work and the bypass circuit to stop working when the batteries in the battery pack need to be switched to series mode; it is also used to control the bypass circuit to work and the buck circuit to stop working when the batteries in the battery pack need to be switched to parallel mode. Utilizing this system, it is possible to automatically switch between series mode and parallel mode according to actual conditions, thereby improving the stability of the terminal device while also increasing battery life.

Description

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 18, 2019, with application number 201910651651X and invention name “A power supply system, method, chip and terminal device for terminal equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of terminal equipment, and in particular to a power supply system, method, chip and terminal equipment for terminal equipment. Background Art

[0003] With the popularization of technology, more and more terminal devices are powered by multiple batteries. When the battery pack of a terminal device includes multiple batteries, the battery pack is usually connected in parallel.

[0004] When a battery pack is connected in parallel, the positive terminals of multiple batteries are connected together, and the negative terminals are connected together. The output voltage of each battery in the battery pack is the same and equal to the output voltage of the battery pack. However, because batteries have internal resistance, which increases as the battery temperature decreases, when the ambient temperature is low, the battery temperature also decreases, and the battery internal resistance increases, which in turn causes the battery output voltage to decrease, which can easily cause the terminal device to shut down.

[0005] Therefore, the stability of the terminal equipment may be reduced when the battery packs are connected in parallel. Summary of the Invention

[0006] The technical solution of the present application provides a power supply system, method, chip and terminal device for a terminal device, which can switch between series mode and parallel mode, thereby improving the stability of the terminal device while also increasing battery life.

[0007] In the first aspect, the technical solution of the present application provides a power supply system for a terminal device, which includes: a battery pack, a bypass circuit, a step-down circuit and a controller; the battery pack includes at least two batteries; the output end of the battery pack is connected to the input end of the step-down circuit, and the output end of the step-down circuit is connected to the power-consuming element of the terminal device; one end of the bypass circuit is connected to the input end of the step-down circuit, and the other end of the bypass circuit is connected to the output end of the step-down circuit; the controller is used to control the step-down circuit to operate and the bypass circuit to stop operating when the batteries in the battery pack need to be switched to series mode, and is also used to control the bypass circuit to operate and the step-down circuit to stop operating when the batteries in the battery pack need to be switched to parallel mode.

[0008] The system's controller can switch between series and parallel modes. Switching the battery packs to series mode increases the output voltage, preventing terminal devices from shutting down due to insufficient power, and improving user stability. Switching the battery packs to parallel mode eliminates the need for a step-down circuit, thereby improving discharge efficiency, extending battery life, and enhancing the user experience.

[0009] In combination with the first aspect, in a first possible implementation method, the controller is used to control the operation of the step-down circuit and control the bypass circuit to stop working, including: when the controller determines that the output voltage of the battery pack is greater than or equal to a first preset voltage threshold, the controller controls the step-down circuit to operate and controls the bypass circuit to stop working.

[0010] The first preset voltage threshold can be greater than the maximum output voltage of the battery pack in parallel mode and less than the minimum output voltage of the battery pack in series mode. The controller determines the operating status of the bypass circuit and the step-down circuit by comparing the output voltage of the battery pack with the first preset voltage threshold.

[0011] In combination with the first aspect and any of the above possible implementations, in a second possible implementation, the controller is further used to determine that the batteries in the battery pack need to be switched to series mode when it is determined that the voltage across the power-consuming element is lower than a second preset voltage threshold.

[0012] The controller can determine the voltage across the power-consuming element based on the current output voltage of the battery pack, the current flowing through the power-consuming element, and the impedance of each circuit component. The second preset voltage threshold can be set as the shutdown threshold voltage of the terminal device. When the voltage across the power-consuming element is less than or equal to the second preset voltage threshold, it indicates that the voltage output capability of the current parallel mode is insufficient to support the normal operation of the power-consuming element, and a switch to series mode should be made.

[0013] In combination with the first aspect and any of the above possible implementations, in a third possible implementation, the controller is further configured to determine, based on the output voltage of the battery pack and the temperature of the battery pack, whether the batteries in the battery pack should be switched to series connection mode. The output voltage of the battery pack can be obtained by sampling the ADC. The controller can detect the resistance of the thermistor to obtain the temperature corresponding to the resistance, thereby determining the battery temperature.

[0014] In combination with the first aspect and any of the foregoing possible implementations, in a fourth possible implementation, the controller is further configured to determine, based on the output voltage and temperature of the battery pack, by looking up a table to determine whether the batteries in the battery pack need to be switched to series connection mode. The output voltage and temperature states recorded in the table may not be exhaustive to reduce storage space occupied by the terminal device. The output voltage and temperature states correspond to state points, and the measured output voltage and temperature of the battery pack may be rounded to the nearest defined state point.

[0015] In combination with the first aspect and any of the above possible implementations, in a fifth possible implementation, the controller selects a table corresponding to the load current based on the load current. When the load current is greater than a preset current, it is determined to be in a large load scenario, and the large load table corresponds to this scenario. When the load current is less than or equal to the preset current, it is determined to be in a small load scenario, and the small load table corresponds to this scenario. The controller can measure the voltage across the current-sensing resistor in the discharge path in real time, and the ratio of the voltage across the current-sensing resistor to the impedance of the current-sensing resistor is the load current. After obtaining the corresponding table, the controller determines the required operating mode of the battery in the battery pack in this scenario by looking up the table based on the output voltage of the battery pack and the temperature of the battery pack.

[0016] In low temperature, low voltage, and heavy load scenarios, the series mode can be used first to prevent abnormal device shutdown; in light load scenarios, the parallel mode can be used to increase the device's battery life.

[0017] In combination with the first aspect and any one of the above possible implementation methods, in a sixth possible implementation method, the controller is also used to obtain a corresponding numerical value based on the output voltage of the battery pack and the temperature of the battery pack. When the numerical value is less than or equal to a preset value, it is determined that the batteries in the battery pack need to be switched to series mode.

[0018] This implementation can reduce the storage space occupied by the terminal device when determining the operating mode that the battery pack should be in.

[0019] In combination with the first aspect and any one of the above possible implementation methods, in a seventh possible implementation method, the controller is used to use a preset function to obtain a function value as a numerical value for the output voltage of the battery pack and the temperature of the battery pack. When the function value is less than or equal to the preset value, it is determined that the batteries in the battery pack need to be switched to series mode; the function value of the preset function is positively correlated with the temperature of the battery pack, and the function value of the preset function is positively correlated with the output voltage of the battery pack.

[0020] For example, the preset value represents the threshold voltage for switching between series and parallel modes at 0°C. When the function value is greater than the preset value, the battery pack should be in parallel mode; when the function value is less than or equal to the preset value, the battery pack should be in series mode. Factors affecting the preset value may include the low-temperature discharge capability of the battery used. The stronger the low-temperature discharge capability of the battery used, the smaller the preset value can be.

[0021] The controller is also configured to select a preset value based on the load current. A load current greater than the preset current corresponds to a heavy load scenario and corresponds to a first preset value. A load current less than or equal to the preset current corresponds to a light load scenario and corresponds to a second preset value. The first preset value being lower than the second preset value indicates that parallel mode is preferred in light load scenarios to increase device battery life.

[0022] In combination with the first aspect and any of the foregoing possible implementations, in an eighth possible implementation, the controller is further configured to determine that the batteries in the battery pack need to be switched to a series mode when it is determined that the low temperature mode button is triggered.

[0023] It can be understood that the low temperature mode button can be a virtual button or a physical button.

[0024] The terminal device's control interface can add a "low-temperature mode" function. In response to a user trigger, the terminal device enters low-temperature mode, and the battery pack is switched to series mode. When the user exits "low-temperature mode," the power supply system switches to automatic mode, and the power supply system controller automatically selects the most appropriate operating mode.

[0025] In combination with the first aspect and any one of the above possible implementations, in a ninth possible implementation, the controller is further used to determine that the batteries in the battery pack need to be switched to series mode when it is determined that the power of the battery pack is lower than a preset power or when it is determined that the low power mode button is triggered.

[0026] It is understandable that the low power mode button can be a virtual button or a physical button.

[0027] The control interface of the terminal device can add a "low power mode" button to enable the user to actively choose to enter "low power mode"; the terminal device can also add a "allow terminal device to automatically enter low power mode" button to enable the user to allow the terminal device to automatically enter low power mode.

[0028] Furthermore, the "low temperature mode" and the "low power mode" can be selected by the user at the same time, for example, the two modes can be set on the control interface of the terminal device at the same time.

[0029] In combination with the first aspect and any of the foregoing possible implementations, in a tenth possible implementation, the bypass circuit includes any of the following switching devices: a transistor, a relay, a load switch, and a metal oxide semiconductor field effect transistor. The step-down circuit includes any of the following: a buck circuit, a switched capacitor, a three-level DC-DC circuit, and a single-ended primary inductor converter.

[0030] In combination with the first aspect and any of the above possible implementations, in an eleventh possible implementation, the battery pack includes at least two batteries: a first battery and a second battery; the battery pack also includes: a first switching tube, a second switching tube and a third switching tube; the positive pole of the first battery is connected to the input end of the step-down circuit; the negative pole of the first battery is connected to the positive pole of the second battery through the second switching tube, and the negative pole of the second battery is grounded; one end of the first switching tube is connected to the negative pole of the first battery, and the other end of the first switching tube is grounded; one end of the third switching tube is connected to the input end of the step-down circuit, and the other end of the third switching tube is connected to the positive pole of the second battery; when the battery needs to be switched to the series mode, the controller controls the first switching tube and the third switching tube to be disconnected, and controls the second switching tube to be closed; when the battery needs to be switched to the parallel mode, the controller controls the second switching tube to be disconnected, and controls the first switching tube and the third switching tube to be closed.

[0031] The controller controls the first switch tube, the second switch tube and the third switch tube to be in different switch combination states, thereby realizing the switching between series connection and parallel connection of batteries in the battery pack.

[0032] In combination with the first aspect and any of the foregoing possible implementations, in a twelfth possible implementation, the power supply system further comprises: a first capacitor; a first end of the first capacitor is connected to the output end of the battery pack, and a second end of the first capacitor is grounded. When the batteries need to switch to series mode, the controller controls the first and third switching tubes to disconnect and controls the second switching tube to close, including: when the batteries need to switch to series mode, the controller controls the first, second, and third switching tubes to disconnect, and controls the second switching tube to close after a first preset time.

[0033] The first capacitor can be used for voltage stabilization and filtering, thereby improving the power supply quality. The length of the first preset time is greater than the length of the dead time of the switch tube. Setting the first preset time can prevent the positive and negative electrodes of the battery cell from short-circuiting during the switching process.

[0034] In combination with the first aspect and any of the foregoing possible implementations, in a thirteenth possible implementation, the power supply system further includes: a second capacitor, wherein a first end of the second capacitor is connected to the output end of the step-down circuit, and a second end of the second capacitor is grounded.

[0035] The second capacitor can be used for voltage stabilization and filtering, thereby improving the quality of power supply. The first capacitor and the second capacitor can be used to maintain a relatively stable output voltage of the power supply system during the dead time.

[0036] In combination with the first aspect and any of the foregoing possible implementations, in a fourteenth possible implementation, when the batteries in the battery pack need to be switched to a parallel mode, the bypass circuit is controlled to operate and the step-down circuit is controlled to stop operating. When the batteries need to be switched to a parallel mode, the controller controls the second switch tube to be disconnected and controls the first switch tube and the third switch tube to be closed, including:

[0037] When the batteries need to switch to parallel mode, the controller controls the first, second, and third switches to disconnect. After a second preset time, the controller controls the first and third switches to close. After a third preset time, the controller controls the bypass circuit to operate and the step-down circuit to stop operating. To prevent a short circuit between the positive and negative electrodes of the batteries during the switching process, the battery pack must first be controlled to switch to series mode before the bypass circuit can be controlled to operate and the step-down circuit can be stopped. Therefore, the third preset time is greater than the dead time of the switches, ensuring that the first and third switches are already in the on state when the controller controls the switching of the step-down and bypass circuits.

[0038] In combination with the first aspect and any of the foregoing possible implementations, in a fifteenth possible implementation, the controller controls the first switch tube and the third switch tube to close after the second preset time, including: when the controller determines that the voltage of the first battery is greater than the voltage of the second battery, the controller controls the first switch tube to close after the second preset time, and controls the third switch tube to close after a fourth preset time; or, when the controller determines that the voltage of the first battery is less than the voltage of the second battery, the controller controls the third switch tube to close after the second preset time, and controls the first switch tube to close again after the fourth preset time; or, when the controller determines that the voltage of the first battery is equal to the voltage of the second battery, the controller controls the first switch tube and the third switch tube to close after the second preset time.

[0039] The fourth preset time, which can be called the balancing time, can be the time it takes for the voltages between the batteries to equalize when the battery pack switches from series mode to parallel mode. Because the controller switches power to the higher-voltage batteries first and the lower-voltage batteries later, the voltage difference between the batteries is reduced, thereby reducing the inrush current between the batteries.

[0040] In a second aspect, the technical solution of the present application provides a chip comprising: a bypass circuit and a step-down circuit. The input end of the step-down circuit is connected to the output end of the battery pack, and the output end of the step-down circuit is connected to the power-consuming element of the terminal device; one end of the bypass circuit is connected to the input end of the step-down circuit, and the other end of the bypass circuit is connected to the output end of the step-down circuit. Both the bypass circuit and the step-down circuit are connected to the controller of the terminal device. When the batteries in the battery pack need to be switched to series mode, the step-down circuit operates in response to the control signal of the controller, and the bypass circuit stops operating. When the batteries in the battery pack are in parallel mode, the bypass circuit operates in response to the control signal of the controller, and the step-down circuit stops operating.

[0041] As described above, the chip includes both a step-down circuit and a bypass circuit. When the power supply system uses the chip, the size of the hardware device can be reduced, saving costs.

[0042] In a third aspect, the technical solution of the present application provides a power supply method for a terminal device, which is applied to a power supply system for the terminal device, the power supply system comprising: a battery pack, a bypass circuit, a step-down circuit, and a controller. The battery pack comprises at least two batteries; the output end of the battery pack is connected to the input end of the step-down circuit, and the output end of the step-down circuit is connected to a power-consuming element of the terminal device; one end of the bypass circuit is connected to the input end of the step-down circuit, and the other end of the bypass circuit is connected to the output end of the step-down voltage; when the batteries in the battery pack are in series mode, the step-down circuit is controlled to operate and the bypass circuit is controlled to stop operating; when the batteries in the battery pack are in parallel mode, the bypass circuit is controlled to operate and the step-down circuit is controlled to stop operating.

[0043] This method can control the switching of batteries within a battery pack between series and parallel modes. Switching the battery pack to series mode increases the output voltage, preventing terminal devices from shutting down due to insufficient power, and improving user stability. Switching the battery pack to parallel mode eliminates the need for a step-down circuit, thereby improving the battery pack's discharge efficiency, extending battery life, and enhancing the user experience.

[0044] In conjunction with the third aspect, in a first possible implementation, the method further includes: determining, based on the output voltage of the battery pack and the temperature of the battery pack, that the batteries in the battery pack need to be switched to series connection mode. The output voltage of the battery pack can be obtained by sampling the ADC. The temperature corresponding to the resistance value is obtained by detecting the resistance value of the thermistor, thereby determining the current battery temperature.

[0045] In combination with the third aspect and any of the foregoing possible implementations, in a second possible implementation, determining that batteries in the battery pack need to be switched to a series mode based on the output voltage and temperature of the battery pack includes:

[0046] Based on the battery pack's output voltage and temperature, a table is looked up to determine whether the batteries in the battery pack need to be switched to series mode. The output voltage and temperature states recorded in the table can be inexhaustible to reduce storage space on the terminal device. The output voltage and temperature states are mapped to form status points. The measured battery pack output voltage and temperature are rounded to the nearest defined status point.

[0047] In combination with the third aspect and any one of the above possible implementation methods, in a third possible implementation method, the method further includes: selecting a table corresponding to the load current based on the load current, and when the load current is greater than the preset current, it is determined to be in a large load scenario, and the large load table corresponds to this; when the load current is less than or equal to the preset current, it is determined to be in a small load scenario, and the small load table corresponds to this.

[0048] This method combines the load, the output voltage of the battery pack, and the battery temperature as the judgment criteria. In low temperature, low voltage, and heavy load scenarios, the series mode is used first to prevent abnormal shutdown of the device; in light load scenarios, the parallel mode is preferred to increase the battery life of the device.

[0049] In combination with the third aspect and any of the above possible implementations, in a fourth possible implementation, the method further includes: determining that the batteries in the battery pack need to switch to series mode when it is determined that the voltage across the power-consuming element is lower than a second preset voltage threshold. The voltage across the power-consuming element can be determined based on the current output voltage of the battery pack, the current flowing through the power-consuming element, and the impedance of each circuit component. The second preset voltage threshold can be set as a shutdown threshold voltage of the terminal device. When the voltage across the power-consuming element is less than or equal to the second preset voltage threshold, it indicates that the voltage output capacity of the current parallel mode is insufficient to support normal operation of the power-consuming element, and switching to series mode should be performed.

[0050] In combination with the third aspect and any of the foregoing possible implementations, in a fifth possible implementation, the method further includes: obtaining corresponding values ​​based on the output voltage and temperature of the battery pack, and determining that the batteries in the battery pack need to be switched to series connection mode when the corresponding values ​​are less than or equal to a preset value. This method can reduce storage space occupied by the interrupt device when determining the operating mode that the battery pack should be in.

[0051] In combination with the third aspect and any of the above possible implementations, in a sixth possible implementation, the method further includes: obtaining a function value as a numerical value using a preset function for the output voltage of the battery pack and the temperature of the battery pack; when the function value is less than or equal to the preset value, determining that the batteries in the battery pack need to be switched to series mode; the function value of the preset function is positively correlated with the temperature of the battery pack, and the function value of the preset function is positively correlated with the output voltage of the battery pack. The preset value is selected according to the load current. When the load current is greater than the preset current, it corresponds to a large load scenario, which corresponds to the first preset value; when the load current is less than or equal to the preset current, it corresponds to a small load scenario, which corresponds to the second preset value. Among them, the first preset value is less than the second preset value, indicating that the parallel mode is more inclined to be used in small load scenarios to increase the battery life of the device.

[0052] In combination with the third aspect and any of the foregoing possible implementations, in a seventh possible implementation, the method further includes: upon determining that the low-temperature mode button is triggered, determining that the batteries in the battery pack need to be switched to series mode. A "low-temperature mode" can be added to the control interface of the terminal device. In response to a user trigger, the terminal device enters low-temperature mode and the battery pack is switched to series mode.

[0053] In combination with the third aspect and any of the foregoing possible implementations, in an eighth possible implementation, the method further includes: upon determining that the power level of the battery pack is lower than a preset power level or determining that a low-power mode button is triggered, determining that the batteries in the battery pack need to be switched to a series connection mode. A "low-power mode" button may be added to the control interface of the terminal device to enable a user to actively select to enter "low-power mode"; the terminal device may also add a "allow terminal device to automatically enter low-power mode" button to enable the user to allow the terminal device to automatically enter low-power mode.

[0054] Furthermore, the "low temperature mode" and the "low power mode" can be selected by the user at the same time, for example, the two modes can be set on the control interface of the terminal device at the same time.

[0055] In a fourth aspect, the technical solution of the present application further provides a terminal device, which includes any of the above-mentioned power supply systems and also includes: a power-consuming element. The power supply system is used to supply power to the power-consuming element.

[0056] Because the terminal device includes the aforementioned power supply system, the controller of the power supply system can control the battery pack to switch between series and parallel modes. Since the series mode increases the output voltage, it prevents the terminal device from shutting down due to insufficient power, thereby improving the stability of the terminal device for users. In parallel mode, the step-down circuit is not required, thereby improving the discharge efficiency of the battery pack and increasing the endurance of the terminal device.

[0057] In conjunction with the fourth aspect, in a first possible implementation, the power supply system of the terminal device includes a battery pack, a bypass circuit, a step-down circuit, and a controller. The battery pack includes a first battery and a second battery. The positive electrode of the first battery is connected to the input of the step-down circuit, the negative electrode of the first battery is connected to the positive electrode of the second battery via a second switch tube, and the negative electrode of the second battery is grounded. One end of the first switch tube is connected to the negative electrode of the first battery, and the other end is grounded. One end of the third switch tube is connected to the input of the step-down circuit, and the other end is connected to the positive electrode of the second battery.

[0058] When the first battery and the second battery have sufficient power and are operating in a light-load scenario or a non-low-temperature environment, the battery pack can be controlled to switch to parallel mode. In parallel mode, there is no need to use a step-down circuit to improve the discharge efficiency of the battery pack and increase the battery life.

[0059] When the power of the first battery and the second battery is insufficient, or when working in a high-load scenario or a low-temperature environment, the battery pack can be controlled to switch to series mode. Since the series mode can increase the output voltage, it can prevent the terminal device from shutting down due to insufficient power supply.

[0060] The controller is configured to determine that the batteries in the battery pack need to be switched to a series connection mode when the voltage across the power-consuming element is determined to be lower than a second preset voltage threshold. The controller is further configured to determine that the batteries in the battery pack need to be switched to a series connection mode based on the output voltage of the battery pack and the temperature of the battery pack.

[0061] In addition, the controller can also determine that the batteries in the battery pack need to be switched to series mode when it is determined that the low temperature mode button is triggered; when it is determined that the power of the battery pack is lower than the preset power or when it is determined that the low power mode button is triggered, the controller can determine that the batteries in the battery pack need to be switched to series mode.

[0062] When the controller controls the battery pack to switch from the parallel mode to the series mode, the battery pack is initially in the parallel mode. In the parallel mode, the second switch tube is in the open state, and the first switch tube and the third switch tube are in the closed state.

[0063] When the battery pack switches from parallel to series mode, the operating states of the buck circuit and bypass circuit can be switched simultaneously. To prevent the high voltage generated by the series connection from directly impacting the downstream circuit, the buck circuit must begin operating before the second switch is closed. This early start-up of the buck circuit is necessary because the buck circuit's opening is not instantaneous; it requires a certain startup time. This startup time, also known as the lead time, is the transition time between switching the buck circuit and controlling the closing of the second switch.

[0064] To prevent a short circuit between the positive and negative electrodes of the battery during the switching process, the controller switches the operating states of the step-down circuit and the bypass circuit. It then controls the first and third switching transistors to be disconnected, keeps the second switching transistor off, and then controls the second switching transistor to be closed after a first preset time. This first preset time can be the dead time of the switching transistor, or it can be greater than the dead time of the switching transistor to provide sufficient time for the switching transistor to complete the switching, further reducing the possibility of a short circuit between the positive and negative electrodes of the battery cell during the switching process.

[0065] During the first preset time, the output voltage of the power supply system is maintained relatively stable by the first capacitor and the second capacitor.

[0066] When the controller controls the battery pack to switch from the series mode to the parallel mode, the battery pack is initially in the series mode. In the series mode, the second switch tube is in the closed state, and the first switch tube and the third switch tube are in the open state.

[0067] When the battery pack switches from series mode to parallel mode, in order to avoid a short circuit between the positive and negative poles of the battery during the switching process, the switching tubes in the battery pack are not switched at the same time. Instead, the second switching tube is first controlled to be disconnected and the first and third switching tubes are kept disconnected. After a second preset time, the first and third switching tubes are controlled to be closed. The second preset time can be the dead time of the switching tube, or it can be greater than the dead time of the switching tube, so as to provide sufficient time for the switching tube to complete the switching, thereby further reducing the possibility of a short circuit between the positive and negative poles of the battery cell itself during the switching process.

[0068] During the first preset time, the output voltage of the power supply system is maintained relatively stable by the first capacitor and the second capacitor.

[0069] To prevent the higher voltage output by the series-connected batteries from directly impacting subsequent circuits during the switching process, the switching between the buck circuit and the bypass circuit must occur a third preset time after the first and third switches switch states. This means the battery pack must first be switched to series mode before the bypass circuit can be activated and the buck circuit can be deactivated. Therefore, this third preset time must be greater than the dead time of the switches to ensure that the first and third switches are already in the on state when the controller switches between the buck circuit and the bypass circuit.

[0070] In one implementation, when batteries are in series mode, differences in capacity or self-discharge rates between the batteries can lead to unequal voltages between them. Switching directly to parallel mode can result in excessive surge currents between the batteries, potentially damaging them. To reduce surge currents, this application also provides a fourth preset time, also known as a balancing time, which is the time it takes for the voltages between the batteries to equalize when the battery pack switches from series mode to parallel mode.

[0071] When the controller determines that the voltage of the first battery is lower than the voltage of the second battery, it first controls the second switch tube to be disconnected, and after a second preset time, it first controls the third switch tube to be closed, and after a fourth preset time, it controls the first switch tube to be closed again, and after the third preset time, it controls the bypass circuit to operate and controls the step-down circuit to stop operating.

[0072] When the controller determines that the voltage of the first battery is equal to the voltage of the second battery, the two batteries can be connected at the same time, and there is no inrush current between the batteries. The controller first controls the second switch tube to be disconnected, and after a second preset time, controls the first switch tube and the third switch tube to be closed. After a third preset time, the controller controls the bypass circuit to operate and controls the step-down circuit to stop operating.

[0073] When the controller determines that the voltage of the first battery is greater than the voltage of the second battery, the controller first controls the second switch tube to be disconnected, and after a second preset time, controls the first switch tube to be closed, and after a fourth preset time, controls the third switch tube to be closed, and after the third preset time, controls the bypass circuit to operate and controls the step-down circuit to stop operating.

[0074] Since the high-voltage battery switches to power supply first, and the low-voltage battery switches to power supply after the balancing time, the voltage difference between the batteries is reduced, thereby reducing the inrush current between the batteries.

[0075] In order to simplify the control signals and control processes when controlling the step-down circuit and the bypass circuit, when the controller determines that the output voltage of the battery pack is higher than the first preset voltage threshold, the controller determines that the step-down circuit is working and the bypass circuit is not working at this time; when the controller determines that the output voltage of the battery pack is lower than or equal to the first preset voltage threshold, the controller determines that the bypass circuit is working and the step-down circuit is not working at this time, so as to realize automatic switching between the bypass circuit and the step-down circuit.

[0076] The first preset voltage threshold is greater than the maximum output voltage of the battery pack in the parallel mode and less than the minimum output voltage of the battery pack in the series mode.

[0077] In the above technical solution, the low temperature mode button can be a virtual button or a physical button. The low power mode button can be a virtual button or a physical button.

[0078] It is understood that the "connection" in the above technical solution can be a direct connection or an indirect connection. For example, the output of the battery pack is connected to the input of the step-down circuit. This can be done by directly connecting the output of the battery pack to the input of the step-down circuit, or by connecting the output of the battery pack to the input of the step-down circuit via a resistor.

[0079] It is understood that the power-consuming components in the above technical solution may be at least one of a CPU (full name: Central Processing Unit), a GPU (full name: Graphics Processing Unit), a baseband processor, a memory, a display, a radio frequency device, an audio device, and a sensor. Of course, the power-consuming components may also be other power-consuming components in the terminal device.

[0080] It is understood that the terminal device in the above technical solution can be a mobile phone, such as a smartphone or a foldable screen phone. It can also be a tablet computer or a wearable device. It can also be a head-mounted device, such as a virtual reality device or an augmented reality device. Of course, the terminal device can also be other terminal devices with a battery.

[0081] It is understandable that the battery pack in the above technical solution can be two batteries, three batteries, or more batteries.

[0082] It is understandable that the controller in the above technical solution can be an application processor or a power management unit PMU. Of course, the controller can also be other processors.

[0083] It can be seen from the above technical solutions that the technical solution of this application has the following beneficial effects:

[0084] The controller in this power supply system can control the step-down circuit to operate and the bypass circuit to stop operating when the batteries in the battery pack are connected in series. It can also control the bypass circuit to operate and the step-down circuit to stop operating when the batteries in the battery pack are connected in parallel. The series mode can increase the output voltage, preventing terminal devices from shutting down due to insufficient power, thereby improving user stability. The parallel mode eliminates the need for a step-down circuit, improving the battery pack's discharge efficiency and increasing battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a schematic diagram of using multiple batteries to power a foldable screen architecture;

[0086] Figure 2 This is a schematic diagram of using multiple batteries for power supply;

[0087] Figure 3 A schematic diagram of multiple batteries provided in an embodiment of the present application in parallel mode;

[0088] Figure 4 A schematic diagram of multiple batteries provided in an embodiment of the present application in a series connection mode;

[0089] Figure 5A schematic diagram of a power supply system for a terminal device provided in an embodiment of the present application;

[0090] Figure 6 A circuit diagram of a power supply system provided in an embodiment of the present application;

[0091] Figure 7 A schematic diagram of a power supply system for another terminal device provided in an embodiment of the present application;

[0092] Figure 8 A schematic diagram of a discharge capacity evaluation circuit provided in an embodiment of the present application;

[0093] Figure 9 A schematic diagram of a mode boundary provided in an embodiment of the present application;

[0094] Figure 10 A schematic diagram of another mode boundary provided in an embodiment of the present application;

[0095] Figure 11 A schematic diagram of a control interface of a terminal device provided in an embodiment of the present application;

[0096] Figure 12 A schematic diagram of a control interface of another terminal device provided in an embodiment of the present application;

[0097] Figure 13a A control timing diagram for switching from parallel mode to series mode provided in an embodiment of the present application;

[0098] Figure 13b A schematic diagram of the parasitic capacitance of an NMOS transistor provided in an embodiment of the present application;

[0099] Figure 13c Vgs curves of the NMOS transistor during the turn-on and turn-off processes provided in the embodiment of the present application;

[0100] Figure 14 A simulation diagram of the parallel mode provided in an embodiment of the present application;

[0101] Figure 15 A simulation diagram of the series mode provided in an embodiment of the present application;

[0102] Figure 16 This is a simulation diagram of mode switching provided in an embodiment of the present application;

[0103] Figure 17 A simulation diagram of the voltage before and after battery mode switching provided in an embodiment of the present application;

[0104] Figure 18 A control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application;

[0105] Figure 19 This is a simulation diagram of the embodiment of the present application when the series mode is switched to the parallel mode;

[0106] Figure 20 Another control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application;

[0107] Figure 21 A control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application;

[0108] Figure 22 A switching simulation diagram without balancing time provided in an embodiment of the present application;

[0109] Figure 23 A switching simulation diagram with a balancing time provided in an embodiment of the present application;

[0110] Figure 24 A schematic diagram of automatic control of a battery operating mode provided in an embodiment of the present application;

[0111] Figure 25 A schematic diagram of automatic control of another battery operating mode provided in an embodiment of the present application;

[0112] Figure 26 A schematic diagram of a chip provided in an embodiment of the present application;

[0113] Figure 27 A flowchart of a power supply method for a terminal device provided in an embodiment of the present application;

[0114] Figure 28 A flow chart of a power supply method when a battery pack provided in an embodiment of the present application switches from a parallel mode to a series mode;

[0115] Figure 29 A flowchart of a power supply method when a battery pack provided in an embodiment of the present application switches from a series mode to a parallel mode;

[0116] Figure 30 A schematic diagram of a terminal device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0117] With the popularization of technology, more and more terminal devices are powered by multiple batteries. The embodiments of the present application do not specifically limit the type of terminal device. The terminal device can be a mobile phone, laptop computer, wearable electronic device (such as a smart watch), tablet computer, augmented reality (AR) device, virtual reality (VR) device, and vehicle-mounted device, etc. that uses multiple batteries to power it.

[0118] The following first introduces a terminal device powered by multiple batteries.

[0119] See also Figure 1 , this figure is a schematic diagram of using multiple batteries to power a folding screen architecture.

[0120] One side of the terminal device with a foldable screen includes a first battery 101 and a first mainboard 103, and the other side includes a second battery 102 and a second mainboard 104. The battery pack formed by the first battery 101 and the second battery 102 supplies power to the terminal device.

[0121] See also Figure 2 ,This figure is a schematic diagram of using multiple batteries for power supply.

[0122] The device includes a SIP mainboard 201, a first battery 101 and a second battery 102. The battery pack formed by the first battery 101 and the second battery 102 supplies power to the terminal device.

[0123] When the battery pack of the terminal device includes multiple batteries, the battery pack is usually connected in parallel. The following description takes the terminal device as a mobile phone, and the battery pack of the terminal device includes two batteries: a first battery and a second battery as an example.

[0124] See also Figure 3 , this figure is a schematic diagram of multiple batteries provided in an embodiment of the present application when they are connected in parallel.

[0125] When the battery pack is in parallel mode, the positive electrode of the first battery 101 is connected to the positive electrode of the second battery 102 to form the positive electrode of the battery pack, and the negative electrode of the first battery 101 is connected to the negative electrode of the second battery 102 to form the negative electrode of the battery pack.

[0126] At this point, the output voltage of each cell in the battery pack is the same, equal to the output voltage of the battery pack. The battery pack's output voltage is relatively low, ranging from 3.6V to 4.2V. Batteries have internal resistance, which increases with decreasing temperature. When the ambient temperature is low, the battery temperature also decreases, increasing the internal resistance from approximately 20mΩ to approximately 1Ω. Under the same current surge, this increased internal resistance causes the battery's output voltage to decrease, and the battery pack's output voltage to decrease accordingly. When the battery pack's output voltage falls below the phone's shutdown threshold (for example, 2.6V), the phone shuts down. This problem often occurs in cold winter weather, affecting users' ability to use their phones outdoors. Furthermore, when the battery charge is low, the battery pack's output voltage is low, which can easily cause the device to shut down.

[0127] Therefore, when the battery packs are connected in parallel, the stability of the terminal equipment will be reduced.

[0128] In order to solve the above technical problems, the embodiment of the present application provides a power supply system for a terminal device, which includes a battery pack, a bypass circuit, a step-down circuit and a controller. The controller included in the power supply system can control the battery pack to switch between series mode and parallel mode. The schematic diagram of the battery pack in parallel mode can be seen in FIG. Figure 3 , the schematic diagram of the battery pack in series mode can be seen in Figure 4 . The controller can also control the step-down circuit to work and the bypass circuit to stop working when it determines that the batteries in the battery pack need to switch to series mode; it can also control the bypass circuit to work and the step-down circuit to stop working when it determines that the batteries in the battery pack need to switch to parallel mode. The controller can control the switching between series mode and parallel mode according to the actual application scenario. Since the series mode can increase the output voltage, it can avoid the terminal device from shutting down due to insufficient power supply, which can improve the stability of the user's use of the terminal device. In parallel mode, there is no need to use a step-down circuit, because it can improve the discharge efficiency of the battery pack, thereby increasing the battery life, thereby improving the user experience.

[0129] The technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application.

[0130] Power supply system embodiment 1:

[0131] See also Figure 5 , which is a schematic diagram of a power supply system for a terminal device provided in an embodiment of the present application.

[0132] The power supply system of the terminal device provided in the embodiment of the present application includes: a battery pack 601, a bypass circuit 602, a step-down circuit 603, a controller 604 and a power-consuming element 605.

[0133] See also Figure 6 , which is a circuit diagram of the power supply system provided in an embodiment of the present application.

[0134] The output of the battery pack 601 is connected to the input of the step-down circuit 603 , the output of the step-down circuit 603 is connected to the power-consuming element 605 of the terminal device, and the two ends of the bypass circuit 602 are connected across the input and output of the step-down circuit 603 .

[0135] The controller 604 is connected to the battery pack 601 , the bypass circuit 602 and the step-down circuit 603 .

[0136] When controller 604 determines that the batteries in battery pack 601 need to be switched to series mode, it controls step-down circuit 603 to operate and bypass circuit 602 to stop operating. In series mode, the output voltage of battery pack 601 is higher than the normal operating voltage of power-consuming element 605. Therefore, battery pack 601 cannot directly supply power to power-consuming element 605, requiring step-down circuit 603 to step down the output voltage of battery pack 601.

[0137] The controller 604 may determine that the batteries need to be switched to the series mode based on various criteria, such as the voltage across the power-consuming element, the output voltage of the battery pack and the battery temperature, or the charge level of the battery pack.

[0138] It is understood that the controller 604 may also simultaneously determine that the batteries need to be switched to the series mode based on at least two of the aforementioned criteria. For example, the controller 604 may control the battery pack to switch to the series mode only when it determines that the battery pack needs to be switched to the series mode based on the voltage across the power-consuming element and also controls the battery pack to switch to the series mode based on the output voltage and battery temperature of the battery pack. Controlling the battery pack to switch to the series mode only when multiple criteria are met may improve the accuracy of the controller's determination that the battery pack needs to be switched to the series mode.

[0139] In this embodiment, the implementation method of the step-down circuit 603 is not specifically limited. A circuit with a step-down function can be used. For example, the step-down circuit 603 can be any one of the following: a Buck circuit, a switched capacitor, a three-level DC-DC circuit, and a single-ended primary inductor converter.

[0140] When controller 604 determines that the batteries in battery pack 601 need to be switched to parallel mode, it controls bypass circuit 602 to bypass step-down circuit 603. In parallel mode, the output voltage of battery pack 601 is low and can be used to power power-consuming components 605, eliminating the need for step-down circuit 603 to step down the output voltage of battery pack 601.

[0141] It is understandable that when the battery pack does not need to operate in the series mode, it can operate in the parallel mode.

[0142] When the controller 604 described in the above embodiment is implemented in a product, it can be specifically implemented as a processor (CPU) of the terminal device, or a PMU (Power Management Unit), or a combination of the CPU and the PMU.

[0143] The implementation of the bypass circuit 602 is not specifically limited in this embodiment. The bypass circuit 602 operates when the battery pack is in parallel mode. For example, the bypass circuit 602 may include the following switching devices:

[0144] Transistors, relays, load switches and Metal Oxide Semiconductor Field Effect Transistors (MOS transistors). MOS transistors can be NMOS transistors or PMOS transistors.

[0145] Figure 6 The bypass circuit 602 is shown as including a single switching device. In actual products, the bypass circuit 602 may also include multiple switching devices. When including multiple switching devices, the multiple switching devices are connected in series. The types of the multiple switching devices may be the same or different. For example, when the bypass circuit 602 includes two identical switching devices, both of which are NMOS transistors, the bypass circuit 602 may include at least two NMOS transistors connected in series.

[0146] The terminal device provided in the embodiment of the present application includes a controller that can control the step-down circuit to work and the bypass circuit to stop working when it is determined that the batteries in the battery pack need to be switched to series mode; it can also control the bypass circuit to work and the step-down circuit to stop working when it is determined that the batteries in the battery pack need to be switched to parallel mode. The controller can control the battery pack to switch between series mode and parallel mode according to the actual application scenario. Since the series mode can increase the output voltage, it can avoid the terminal device from shutting down due to insufficient power supply, thereby improving the stability of the user's use of the terminal device. In parallel mode, it is not necessary to use a step-down circuit because the discharge efficiency of the battery pack can be improved, thereby increasing the battery life and improving the user experience.

[0147] The battery pack of this power supply system can realize the switch between parallel mode and series mode. The following first explains the working principle of the battery switching from parallel mode to series mode.

[0148] Power supply system embodiment 2:

[0149] See also Figure 7 , this figure is a schematic diagram of a power supply system of another terminal device provided in an embodiment of the present application.

[0150] The battery pack 601 of the power supply system includes at least two batteries: a first battery 601a and a second battery 601b. The output voltage of the first battery 601a is V1, and the output voltage of the second battery 601b is V2. The battery pack 601 also includes a first switch tube Q1, a second switch tube Q2, and a third switch tube Q3.

[0151] The positive electrode of the first battery 601a is connected to the input end of the step-down circuit 603, the negative electrode of the first battery 601a is connected to the positive electrode of the second battery 601b through the second switch tube Q2, and the negative electrode of the second battery 601b is grounded.

[0152] One end of the first switch Q1 is connected to the negative electrode of the first battery 601a, and the other end is grounded. One end of the third switch Q3 is connected to the input end of the step-down circuit 603, and the other end is connected to the positive electrode of the second battery 601b.

[0153] The switches Q1, Q2, and Q3 can be any one or a combination of transistors, relays, load switches, and metal oxide semiconductor field effect transistors. Typically, in a specific product, Q1, Q2, and Q3 can use the same type of switch so that the controller can control them using the same control signal, but this is not specifically limited in this embodiment. The controller can control different switch combinations of Q1, Q2, and Q3 to achieve series and parallel connection of the first battery 601a and the second battery 601b.

[0154] In this embodiment, the bypass circuit 602 includes the fourth switch tube Q4 and the step-down circuit 603 is a Buck circuit.

[0155] The controller is not shown in the figure. When the controller determines that the first battery 601a and the second battery 601b need to be switched to the series mode, the controller controls the first switch tube Q1 and the third switch tube Q3 to be disconnected and controls the second switch tube Q2 to be closed.

[0156] The power supply system may also include a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is connected to the output end of the battery pack 601, and the second end of the first capacitor C1 is grounded. The first end of the second capacitor C2 is connected to the input end of the power-consuming element 605, and the second end of the second capacitor C2 is grounded. Both the first capacitor C1 and the second capacitor C2 can be used for voltage stabilization and filtering, thereby improving the quality of power supply. In addition, for actual terminal devices, the first capacitor C1 and the second capacitor C2 can actually be equivalent capacitors formed by multiple capacitors.

[0157] When the controller determines that the first battery 601a and the second battery 601b need to be switched to the parallel mode, the controller controls the second switch tube Q2 to be turned off, and controls the first switch tube Q1 and the third switch tube Q3 to be turned on.

[0158] The following specifically describes how the controller determines whether the batteries in the battery pack 601 are switched between the parallel mode and the series mode.

[0159] Method 1: Determine the operating mode of the battery pack by the voltage across the power-consuming component.

[0160] The controller can determine the voltage across the power-consuming element based on the current output voltage of the battery pack, the current flowing through the power-consuming element, and the impedance of each circuit component. When the controller determines that the voltage across the power-consuming element is lower than a second preset voltage threshold, it determines that the battery pack needs to switch from parallel mode to series mode. This second preset voltage threshold can be set to the shutdown threshold voltage of the terminal device, for example, 2.6V.

[0161] The following is a detailed description with reference to the accompanying drawings.

[0162] See also Figure 8 , which is a schematic diagram of the discharge capacity evaluation circuit provided in an embodiment of the present application.

[0163] When the battery pack is in parallel mode, the first switch Q1 and the third switch Q3 are both closed, the second switch is off, and the bypass circuit is in operation. In parallel mode, the cell voltages of the first battery 601a and the second battery 601b are equal, that is, V1 = V2.

[0164] Rcell1 and Rcell2 represent the equivalent internal resistance of the first battery 601a and the second battery 601b, respectively. Rconnector is the equivalent impedance of the battery connector. Rpcb is the equivalent impedance of the board trace. Rq1, Rq3, and Rq4 are the equivalent impedances of the switches Q1, Q3, and Q4 when they are turned on, respectively. All of the above impedances are known parameters.

[0165] The controller can measure the voltage across the current sense resistor (Current Sense Resistor) R0 in the discharge path in real time and determine the current Iload flowing through the power-consuming element 605 based on the ratio of the voltage across the current sense resistor to the impedance of the current sense resistor. The batteries included in the battery pack can be connected to the terminal device via a battery connector. The current sense resistor R0 can be located near the battery connector to detect the current of the battery pack. The output voltage Vout of the power supply system can be determined by the following formula:

[0166] Vout=V1-((Rcell1+Rq1) / / (Rcell2+Rq3)+Rconnector+Rq4+Rpcb+R0)×Iload(1)

[0167] In formula (1), (Rcell1+Rq1) / / (Rcell2+Rq3) represents the resistance when Rcell1 and Rq1 connected in series are connected in parallel with Rcell2 and Rq3 connected in series. When Vout determined by formula (1) is less than or equal to the second preset voltage threshold, the voltage output capability of the current parallel mode is insufficient to support the normal operation of the power-consuming element 605, and the system should switch to the series mode.

[0168] It should be noted that the battery internal resistance Rcell1 and Rcell2 may both be related to the battery temperature, and the battery internal resistance will increase as the temperature decreases. Therefore, in a low temperature environment, the Vout determined by formula (1) is greater than the actual output voltage of the power supply system. In order to promptly switch the batteries of the battery pack 601 to the series mode, in one possible implementation, different battery temperatures can correspond to different second preset voltage thresholds. When the battery temperature is low, the corresponding second preset voltage threshold is higher. The correspondence between the battery temperature and the second preset voltage threshold is stored in the terminal device in advance. The second preset voltage threshold corresponding to the current temperature can be obtained by real-time detection of the battery pack temperature. The output voltage Vout of the current power supply system determined according to formula (1) is compared with the second preset voltage threshold corresponding to the current temperature to determine whether the battery pack should be switched to the series mode.

[0169] In another possible implementation, since the relationship between the change in the battery internal resistance Rcell1 and Rcell2 with temperature can be a predetermined functional relationship, the temperature of the first battery 601a and the second battery 601b can be detected in real time, and then the corresponding resistances Rcell1 and Rcell2 at the current temperature are determined according to the predetermined functional relationship, and then the output voltage Vout of the current power supply system is determined according to formula (1), and the output voltage Vout of the power supply system is compared with the second preset voltage threshold to determine whether the battery pack should be switched to the series mode. At this time, the second preset voltage threshold can be set to the shutdown threshold voltage of the terminal device, for example, the shutdown threshold voltage can be 2.6V.

[0170] Temperature can be measured using a thermistor. The relationship between the thermistor's resistance and temperature can be a predetermined function. The controller measures the resistance of the thermistor inside the battery to determine the battery temperature corresponding to that resistance. An NTC (Negative Temperature Coefficient) thermistor can be used within the battery.

[0171] Method 2: Use the table lookup method to determine the working mode of the battery pack.

[0172] The controller selects the table corresponding to the load current based on the load current. Load currents greater than a preset current correspond to the high-load table, while load currents less than or equal to the preset current correspond to the low-load table. The controller determines the battery pack's operating mode by searching the corresponding table based on the battery pack's output voltage and temperature.

[0173] The controller can measure the voltage across the current-sense resistor in the discharge path in real time. The ratio of the voltage across the current-sense resistor to the resistance of the current-sense resistor is the load current. The output voltage of the battery pack can be sampled using the ADC. The controller detects the resistance of the thermistor, obtains the temperature corresponding to that resistance, and thus determines the battery temperature. An NTC thermistor can be used in the battery.

[0174] The controller determines whether the current load current is greater than a preset current. This preset current is determined based on the actual terminal device and is not specifically limited in this embodiment. When the load current is greater than the preset current, the controller determines that the current is a heavy load scenario. When the load current is less than the preset current, the controller determines that the current is a light load scenario. Heavy load scenarios and light load scenarios correspond to different tables.

[0175] The following uses the large load table shown in Table 1 and the small load table shown in Table 2 as examples for explanation. In the table, "series" indicates series mode, and "parallel" indicates parallel mode.

[0176] Table 1 Large load table

[0177]

[0178] Table 2 Small load table

[0179]

[0180] The following example illustrates how the controller determines the operating mode that the battery pack should be in through a table.

[0181] For example, when the load current is greater than the preset current, it is determined to be a heavy load scenario and corresponds to the heavy load table. When the detected battery voltage is 3.5V and the battery temperature is 0°C, Table 1 shows that the battery pack should switch to parallel mode.

[0182] Due to limited storage space in the terminal device, the voltage / temperature states in the table do not need to be exhaustive. The measured voltage and temperature can be rounded to the nearest defined state point. For example, when the load current is greater than the preset current, the battery voltage is 3.7V, and the battery temperature is 2°C, the corresponding large load table is first determined. Then, the defined state point closest to 3.7V is determined to be 3.5V, and the defined state point closest to 2°C is 0°C. Therefore, (3.7V, 2°C) is rounded to (3.5V, 0°C), and the corresponding parallel discharge mode is determined from the table.

[0183] See also Figure 9 , which is a schematic diagram of the pattern boundary provided in an embodiment of the present application.

[0184] The corresponding data in Tables 1 and 2 can be used to determine the mode boundaries for heavy and light load scenarios. The figure shows the solid line for the heavy load scenario (Table 1) and the dashed line for the light load scenario (Table 2). This figure provides a more vivid representation of the aforementioned tables. The coordinates of a state point can be expressed as (battery temperature, battery voltage), and the region in which the state point is located can be used to determine the battery's operating mode at that time.

[0185] The current mode boundary is determined based on the relationship between the load current and the preset current. When the state point falls to the right of the mode boundary, parallel mode is optimal for this scenario and the switch should be made to parallel mode. When the state point falls to the left of the mode boundary, series mode is optimal for this scenario and the switch should be made to series mode. It should be noted that the mode boundary for large loads is further to the right than that for small loads.

[0186] In the above description, the mode boundary determined by the table is a straight line. In addition, the mode boundary can also be a curve. For details, please refer to Figure 10 Schematic diagram of the mode boundaries shown.

[0187] The above example is for illustrative purposes only. The mode boundaries are determined by the actual working conditions of the terminal device. Different terminal devices may have different corresponding tables and corresponding mode boundaries.

[0188] From the above, we can see that in low temperature, low voltage, and heavy load scenarios, the series mode is preferred to prevent abnormal device shutdown; in light load scenarios, the parallel mode is preferred to increase the device's battery life.

[0189] Method 3: Use function value to determine the working mode of the battery pack.

[0190] In order to reduce the storage space occupied by the terminal device, a preset function f can also be used to replace the above table. The controller substitutes the output voltage U and battery temperature T of the battery pack 601 into the preset function f to obtain the function value. When the function value is less than or equal to the preset value, it is determined that the batteries in the battery pack 601 need to be switched to series mode.

[0191] The controller is further configured to select the preset value based on the magnitude of the load current. A first preset value corresponds to a load current greater than the preset current, and a second preset value corresponds to a load current less than or equal to the preset current. The first preset value is smaller than the second preset value. That is, a heavy load scenario corresponds to the first preset value, and a light load scenario corresponds to the second preset value.

[0192] This preset value represents the threshold voltage for switching between series and parallel modes at 0°C. For example, a heavy load scenario corresponds to the first preset value. When the function value is greater than the first preset value, the battery pack should be in parallel mode; when the function value is less than or equal to the first preset value, the battery pack is suitable for series mode.

[0193] The preset value can be obtained in advance through experiments. For example, when the battery temperature is determined to be 0°C, a discharge test is performed on batteries of different voltages, and the voltage drop is measured. If the voltage drops below the shutdown threshold voltage of the terminal device (for example, 2.6V) during the discharge test, then the voltage is the preset value corresponding to the current load conditions.

[0194] The primary factor affecting this preset value is the low-temperature discharge capability of the battery used. The stronger the low-temperature discharge capability of the battery used, the smaller the preset value can be. The value of the preset function is positively correlated with the battery temperature T, and the value of the preset function is positively correlated with the output voltage U of the battery pack. The preset function is set based on the actual operating requirements of the terminal device and is not specifically limited in this embodiment of the present application.

[0195] The following description is made by taking the preset function as a linear function f=a×T+U and combining the data in Table 1 and Table 2 as an example. It is understandable that the preset function f may also be other types of functions, such as an exponential function. For example, the preset function is as follows:

[0196] f=0.05×T+U(2)

[0197] In addition, the first preset value is 3 and the second preset value is 2.5. In a heavy load scenario, when f≤3, the batteries in battery pack 601 should be in series mode, and when f>3, the batteries in battery pack 601 should be in parallel mode. In a light load scenario, when f≤2.5, the batteries in battery pack 601 should be in series mode, and when f>2.5, the battery pack should be in parallel mode.

[0198] For example, when the load current is greater than the preset current and the current battery voltage is 3.7V and the battery temperature is 2°C, this corresponds to the first preset value. Formula (2) shows that f = 3.8. Since f > 3, this corresponds to the parallel mode. It can be seen that the above method achieves the same result as the lookup table in Method 3.

[0199] In addition, since the first preset value corresponding to the heavy load scenario is greater than the second preset value corresponding to the heavy load scenario, this also indicates that the parallel mode is more likely to be used in the light load scenario to increase the battery life of the device.

[0200] The terminal device can switch the working mode of the battery pack through the above implementation. In addition, the terminal device can also force the switching through the control interface of the terminal device, that is, the user of the terminal device can trigger the switching.

[0201] See also Figure 11 , which is a schematic diagram of a control interface of a terminal device provided in an embodiment of the present application.

[0202] Add "low temperature mode" to the control interface of the terminal device. In one possible implementation, the user can determine whether to enter the low temperature mode based on the current ambient temperature. For example, when the user is outdoors in the cold, in order to enable the terminal device to work stably, the user can choose to enter the "low temperature mode". In another possible implementation, the control interface of the terminal device can display the temperature of the battery in real time. When the battery temperature is lower than the preset temperature value (for example, -10°C), the user is prompted to enter the "low temperature mode" to improve the stability of the terminal device. When the user chooses to enter the "low temperature mode", the controller determines that the low temperature mode button is triggered, and the battery pack is switched to series mode. When the user exits the "low temperature mode", the power supply system switches to automatic mode, and the controller of the power supply system automatically selects the most appropriate working mode.

[0203] It is understood that the terminal device's control interface has a "low temperature mode" that, in response to a user trigger, enters low temperature mode and switches the battery packs to series mode. In this case, the ambient temperature of the terminal device may not be related, but rather the battery packs switch to series mode based on the user triggering "low temperature mode".

[0204] It is understandable that the above buttons can be physical buttons or corresponding icons on the touch screen.

[0205] See also Figure 12 , which is a schematic diagram of a control interface of another terminal device provided in an embodiment of the present application.

[0206] A "Low Power Mode" function has been added to the terminal device's control interface. When the user actively selects "Low Power Mode," the controller determines that the Low Power Mode button has been triggered and the battery packs switch to series mode. When the user exits "Low Power Mode," the power supply system switches to automatic mode, and the controller automatically selects the most appropriate operating mode.

[0207] Furthermore, the terminal device may also have a setting button that allows automatic entry into low-power mode. For example, an option "Allow terminal device to automatically enter low-power mode" may be added to the control interface. The user can enable this option to allow the terminal device to automatically enter low-power mode. That is, when the controller determines that the battery pack power level is lower than a preset power level, the terminal device is controlled to automatically enter "low-power mode" and determine that the battery pack is in series mode. The embodiment of the present application does not specifically limit the preset power level. For example, the preset power level can be 10% or 15% of the total power level, and the user can also adjust the preset power level on the terminal device according to actual conditions.

[0208] Furthermore, the "low temperature mode" and the "low power mode" can be selected by the user at the same time, for example, the two modes can be set on the control interface of the terminal device at the same time.

[0209] The controller can realize the switching of the battery pack from the parallel mode to the series mode through any of the above methods. The following takes the example that the first switch tube Q1, the second switch tube Q2 and the third switch tube Q3 are all NMOS tubes, and combines the accompanying drawings to specifically illustrate the working principle of the controller controlling the battery pack to switch from the parallel mode to the series mode.

[0210] See also Figure 13a and Figure 7 , Figure 13a This is a control timing diagram for switching from parallel mode to series mode provided in an embodiment of the present application.

[0211] The controller controls the bypass circuit 602 and the buck circuit 603 via an enable signal. The enable signal may be a level signal that can control the working states of the switches in the bypass circuit 602 and the buck circuit 603.

[0212] When the enable signal of the bypass circuit 602 is at a high level, the controller controls the bypass circuit 602 to operate; when the enable signal of the bypass circuit 602 is at a low level, the controller controls the bypass circuit 602 to stop operating.

[0213] When the enable signal of the step-down circuit 603 is at a high level, the controller controls the step-down circuit 603 to operate; when the enable signal of the step-down circuit 603 is at a low level, the controller controls the step-down circuit 603 to stop operating.

[0214] Vgs is the voltage between the gate and source of the switch tube. When Vgs is high, the switch tube is turned on, and when Vgs is low, the switch tube is turned off.

[0215] When the controller switches the batteries from parallel mode to series mode, it is necessary to activate the buck circuit 603 and deactivate the bypass circuit 602. To prevent the higher voltage output from the batteries connected in series from directly impacting subsequent circuits, the switching between the buck circuit 603 and the bypass circuit 602 can be performed before the states of the switches Q1, Q2, and Q3 are switched.

[0216] Initially, the batteries are in a parallel mode. In the parallel mode, the second switch tube Q2 is in an open state, and the first switch tube Q1 and the third switch tube Q3 are in a closed state.

[0217] To prevent a short circuit between the positive and negative electrodes of the battery during the switching process, for example, when the second switch Q2 and the third switch Q3 are simultaneously turned on, the positive and negative electrodes of the first battery 601a are short-circuited; when the first switch Q1 and the second switch Q2 are simultaneously turned on, the positive and negative electrodes of the second battery 601b are short-circuited; or when the first switch Q1, the second switch Q2, and the third switch Q3 are all simultaneously turned on, the positive and negative electrodes of the first battery 601a and the positive and negative electrodes of the second battery 601b are short-circuited. The switches in the battery pack 601 are not switched simultaneously. Instead, the first switch Q1 and the third switch Q3 are first turned off, and the second switch Q2 is kept off. After a first preset time, the second switch Q2 is then turned on. The first preset time can be the dead time of the NMOS transistor.

[0218] See also Figure 13b and Figure 13c , Figure 13b A schematic diagram of the parasitic capacitance of an NMOS tube provided in an embodiment of the present application, Figure 13c The Vgs curves of the NMOS tube during the turn-on and turn-off processes provided in the embodiment of the present application.

[0219] The dead time is set in the embodiment of the present application to avoid short circuit between the positive and negative electrodes of the battery cell during the switching process. For NMOS tube, there is a parasitic capacitance C between the gate and the source. GS When the control signal of the controller arrives, due to the parasitic capacitance C between the gate and the source GS Charging and discharging take a certain amount of time, so there will be a delay in the on and off of the NMOS tube. GS The smaller it is, the stronger the driving capability of the control signal is, the shorter the charging and discharging time is, the smaller the delay is, and a smaller dead time can be set.

[0220] Due to semiconductor process limitations, C GS The discreteness is large. In order to avoid short circuit between the positive and negative electrodes of the battery cell during the switching process, sufficient dead time should be guaranteed. For example, when the selected NMOS tube model is DMG7430LFG, its C GS The capacitance value is 1.28nF. When the driver control chip is AUIRS2191S, its driving capability is 3.5A. When this driver chip drives the above NMOS transistor, the measured dead time should be ≥100ns.

[0221] It can be understood that the first preset time can also be greater than the dead time of the NMOS tube to provide sufficient time for the switch tube to complete the switching, further reducing the possibility of short circuit between the positive and negative poles of the battery cell during the switching process. For example: when the dead time is 100ns, the first preset time can be greater than the dead time, for example, it can be set to 110ns.

[0222] Since the first switch tube Q1 and the third switch tube Q3 are first controlled to be off, and the second switch tube Q2 is kept off, and the second switch tube Q2 is controlled to be closed after the dead time, the switch tubes Q1, Q2 and Q3 are all off during the dead time, and the batteries in the battery pack are not connected to the circuit. At this time, the first capacitor C1 and the second capacitor C2 can maintain the output voltage of the power supply system relatively stable during the dead time.

[0223] During the dead time, the power-consuming components are powered by the first and second capacitors C1 and C2. Therefore, the length of the dead time is proportional to the sum of the capacitances of the first and second capacitors C1 and C2. That is, the longer the dead time, the greater the required sum of the capacitances of C1 and C2. The sum of the capacitances of the first and second capacitors C1 and C2 included in the terminal device is typically in the order of 200 μF, while the dead time is typically in the order of 100 ns. This sum of the capacitances of the first and second capacitors C1 and C2 is sufficient to maintain a relatively stable output voltage of the power supply system during the dead time. The following example illustrates this.

[0224] Q represents the charge, U before Indicates the voltage across the first capacitor C1 and the second capacitor C2 before the dead time, U after Represents the voltage across the first capacitor C1 and the second capacitor C2 after the dead time, T DeadTime Indicates the length of the dead time, I pulse represents the load current during the dead time. The following formula can be obtained from the law of conservation of charge:

[0225] Q=(C1+C2)×U before =(C1+C2)×U after +I pluse ×T DeadTime (3)

[0226] Take U drop Represents the voltage drop during the dead time. U can be determined by formula (3) drop Satisfies the following formula:

[0227]

[0228] When the sum of the capacitance values ​​of the first capacitor C1 and the second capacitor C2 is 200μF, that is, C1+C2=200uF, the dead time T DeadTime=100ns, load current I during dead time pulse =10A, the voltage drop U during the dead time can be determined by formula (4): drop =5mV, the voltage drop is small and will hardly affect the normal operation of the terminal device. Therefore, it can be seen that the sum of the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can meet the requirement of maintaining the output voltage of the power supply system relatively stable during the dead time.

[0229] The controller simultaneously switches the operating states of the bypass circuit 602 and the buck circuit 603, that is, it controls the buck circuit 603 to operate while controlling the bypass circuit 602 to stop working. The transition time between switching the buck circuit 603 and the bypass circuit 602 and controlling the second switch tube Q2 to close can be called the lead time.

[0230] In the process of switching the battery pack from parallel mode to series mode, the buck circuit 603 needs to start working before the second switch tube Q2 is closed to prevent the high voltage generated by the battery series from directly impacting the subsequent circuit. The buck circuit 603 needs to start working in advance because the opening of the buck circuit 603 is not instantaneous, but requires a certain startup time. The startup time is the lead time, which is related to the chip model of the buck circuit 603. Different chip models can correspond to different lead times. For example, if the core model of the buck circuit 603 is TPS54610, its startup time is 3.35ms, so the lead time should be ≥3.35ms. The controller of the power supply system provided in the embodiment of the present application controls the battery pack to switch from parallel mode to series mode based on real-time information such as the temperature of the battery pack, the battery output voltage and the load current. Therefore, the controller can control the battery pack to switch from parallel mode to series mode in scenarios such as low ambient temperature (such as outdoors in winter), low battery charge, and heavy load. Because series mode can increase the output voltage, it can reduce the probability of terminal device shutdown due to insufficient power supply, improve the stability of terminal devices in such scenarios, and thus enhance the user experience in such scenarios. The following is a detailed explanation with reference to the simulation diagram.

[0231] See also Figure 14 , which is a simulation diagram of the parallel mode provided in an embodiment of the present application.

[0232] The simulation conditions are: battery voltage of 4.0V, battery internal resistance of 1Ω (battery internal resistance is higher at low temperatures), load current of 2A, and the terminal device's shutdown threshold voltage of 2.6V. When the batteries are in parallel mode, the battery pack's output voltage V(out) drops to 2.5V, which is lower than the terminal device's shutdown threshold voltage, causing the terminal device to shut down abnormally.

[0233] See also Figure 15, which is a simulation diagram of the series mode provided in an embodiment of the present application.

[0234] Under the same simulation conditions, since the controller controls the battery to switch from parallel mode to series mode, V(out) is the input voltage of the power consumption element, which corresponds to Figure 7 The voltage at point A, V(out), is 3.4V, which is still higher than the shutdown threshold voltage of the terminal device. At this time, the terminal device will not be abnormally shut down.

[0235] Furthermore, the controller achieves smooth switching between the bypass circuit and the step-down circuit when switching the batteries from parallel to series connection mode. This reduces the voltage impact on subsequent circuits caused by the higher output voltage of the series-connected batteries. It also avoids short circuits between the positive and negative electrodes of the batteries during the switching process, further improving the stability of the terminal device. This is explained in detail below with reference to simulation diagrams.

[0236] See also Figure 16 , which is a simulation diagram of mode switching provided in an embodiment of the present application.

[0237] When the controller switches the battery from parallel mode to series mode, the bypass circuit 602 stops working and the buck circuit 603 starts working. In the figure, V(input) is the total input voltage of the first battery 601a and the second battery 602b (black line in the figure), V(n006) is the voltage of the left end node B of the inductor L1 in the buck circuit 603 (dark gray line in the figure), and V(out) is the input voltage of the power consumption component, which corresponds to Figure 7 The voltage at point A (light gray line in the figure) and the V(out) curve show that the voltage fluctuation range of V(out) is small before and after the battery switches to series mode, indicating that smooth switching between the bypass circuit and the buck circuit is achieved, with little impact on the stability of the terminal equipment.

[0238] See also Figure 17 , this figure is a simulation diagram of the voltage before and after the battery mode switching provided in an embodiment of the present application.

[0239] This figure more clearly reflects the voltage changes before and after the battery mode switch, where V(input) is the total input voltage of the first battery 601a and the second battery 602b. When the batteries switch from parallel mode to series mode, V(input) increases from approximately 3.8V to approximately 7.6V. Observing the V(out) curve, it can be found that the voltage fluctuation range of V(out) is relatively small before and after the battery mode switch, indicating that the battery switching to series mode has little impact on the downstream circuit, and can maintain a relatively stable output voltage.

[0240] The above embodiment illustrates the working principle of the controller controlling the batteries to switch from the parallel mode to the series mode. The following describes the working principle of the controller controlling the batteries to switch from the series mode to the parallel mode.

[0241] Power supply system embodiment 3:

[0242] Continue to see Figure 7 When the controller determines that the first battery 601a and the second battery 601b need to be switched to the parallel mode, the controller controls the second switch tube Q2 to be disconnected, and controls the first switch tube Q1 and the third switch tube Q3 to be closed.

[0243] The various ways in which the controller determines that the batteries in the battery pack 601 need to switch from series mode to parallel mode can be found in the relevant description of Example 2, which will not be repeated in this embodiment. The following specifically describes the working principle of the controller controlling the battery pack to switch from series mode to parallel mode.

[0244] See also Figure 18 , this figure is a control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application.

[0245] When the controller controls the batteries to switch from series mode to parallel mode, the bypass circuit 602 needs to be operated and the buck circuit 603 needs to be stopped. In order to prevent the higher voltage output by the series batteries from directly impacting the subsequent circuit during the switching process, the switching of the buck circuit 603 and the bypass circuit 602 needs to be performed after the states of the switch tubes Q1, Q2 and Q3 are switched.

[0246] Initially, the battery pack is in series mode, with the second switch Q2 in a closed state and the first switch Q1 and the third switch Q3 in an open state. When the switch controls the battery to switch from series mode to parallel mode, the first switch Q1 and the third switch Q3 remain open. To prevent a short circuit between the positive and negative electrodes of the battery during the switching process, the switches within the battery pack 601 are not switched simultaneously. Instead, the second switch Q2 is first controlled to be open, and after a second preset time, the first switch Q1 and the third switch Q3 are controlled to be closed. After a third preset time, the bypass circuit 602 is controlled to operate and the step-down circuit 603 is stopped. The second preset time may be a dead time. For a detailed description of the dead time, please refer to the second embodiment of the system, which will not be repeated here. The sum of the dead time and the third preset time is the lag time.

[0247] In order to avoid a short circuit between the positive and negative poles of the battery during the switching process, it is necessary to first control the battery pack to switch to the series mode, and then control the bypass circuit 602 to work and the buck circuit 603 to stop working. Therefore, the third preset time needs to be greater than the dead time of the NMOS tube to ensure that when the controller controls the switching of the buck circuit 603 and the bypass circuit 602, the first switch tube Q1 and the third switch tube Q3 are already in the on state.

[0248] During the dead time, the first switch Q1 , the second switch Q2 and the third switch Q3 are all turned off. At this time, the first capacitor C1 and the second capacitor C2 are used to maintain a relatively stable output voltage of the power supply system during the dead time.

[0249] The controller of the power supply system provided in the embodiment of the present application can control the battery pack to switch from series mode to parallel mode based on real-time information such as the battery pack temperature, battery output voltage, and load current. Therefore, the controller can control the battery pack to switch from series mode to parallel mode in scenarios where the ambient temperature is relatively normal, the battery pack has sufficient charge, and the load is light, thereby improving the battery pack's discharge efficiency, extending the battery life of the terminal device, and thus improving the user experience in such scenarios.

[0250] Furthermore, the controller can stabilize the switching process when controlling the batteries to switch from series mode to parallel mode, further improving the stability of the terminal device. This is explained in detail below with reference to simulation diagrams.

[0251] See also Figure 19 , this figure is a simulation diagram when the series mode of an embodiment of the present application is switched to the parallel mode.

[0252] Observing the V(out) curve, we can find that when the battery switches from series mode to parallel mode, the voltage fluctuation range of V(out) is small and always higher than the shutdown threshold voltage of the terminal device. This indicates that the battery mode switching is excessively smooth, has little impact on the subsequent circuit, and can maintain a relatively stable output voltage.

[0253] When batteries are in series mode, differences in capacity or self-discharge rates between the batteries can lead to unequal voltages between them. Switching directly to parallel mode at this point can result in excessive inrush current between the batteries, potentially damaging the batteries. The following, combined with the accompanying figures, details the principle behind how the controller reduces inrush current when switching batteries from series to parallel mode.

[0254] Power supply system embodiment 4:

[0255] The controller obtains the voltages of the first battery 601a and the second battery 601b through ADC sampling. When the controller determines that the voltage V1 of the first battery 601a is greater than the voltage V2 of the second battery 601b, the controller first controls the second switch Q2 to be off. After a second preset time, the controller controls the first switch Q1 to be on. After a balance time, the controller controls the third switch Q3 to be on. After a third preset time, the controller controls the bypass circuit 602 to be on and the step-down circuit 603 to be off. The second preset time may be a dead time. For details about the dead time and the third preset time, please refer to the above-mentioned power supply system embodiment and will not be repeated in this embodiment.

[0256] The balance time can be called the fourth preset time, which is the time it takes for the voltage between batteries to be balanced when the battery pack switches from series mode to parallel mode. Figure 7 For example, the balancing time is determined by the voltage difference between the first battery 601a and the second battery 601b, as well as the internal resistance of the first battery 601a and the second battery 601b. The greater the voltage difference between the batteries and the greater the internal resistance, the longer the required balancing time. If there is no voltage difference between the two batteries, no balancing time is required. For example, when the battery voltages of the first battery 601a and the second battery 601b are 4.1V and 4.0V, respectively, and the battery internal resistance is 260mΩ, the balancing time is ≥ 10us to reduce the inrush current between the batteries to below 0.5A. When the controller determines that the voltage V1 of the first battery 601a is less than the voltage V2 of the second battery 601b, the controller first controls the second switch Q2 to open. After a second preset time, the controller first controls the third switch Q3 to close. After a fourth preset time, the controller controls the first switch Q1 to close. After the third preset time, the controller controls the bypass circuit 602 to operate and the step-down circuit 603 to stop operating.

[0257] When the controller determines that the voltage V1 of the first battery 601a is equal to the voltage V2 of the second battery 601b, the controller first controls the second switch tube Q2 to be disconnected, and after a second preset time, controls the first switch tube Q1 and the third switch tube Q3 to be closed. After a third preset time, the controller controls the bypass circuit 602 to operate and controls the step-down circuit 603 to stop operating.

[0258] When the controller determines that the voltage V1 of the first battery 601a is greater than the voltage V2 of the second battery 601b, the controller first controls the second switch tube Q2 to be disconnected, and after a second preset time, controls the first switch tube Q1 to be closed, and after a fourth preset time, controls the third switch tube Q3 to be closed. After a third preset time, the controller controls the bypass circuit 602 to operate and controls the step-down circuit 603 to stop operating.

[0259] The following describes the control principle of the controller using the example of a case where the battery voltage V2 of the second battery 601b in the battery pack 601 is higher than the battery voltage V1 of the first battery 601a. ​​If the battery voltage V2 of the second battery 601b is lower than the battery voltage V1 of the first battery 601a, the control principle of the controller is similar and will not be further described here.

[0260] See also Figure 20 , this figure is another control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application.

[0261] The controller first controls the second switch Q2 to open. After the dead time, it controls the third switch Q3 to close. At this time, the second battery 601b with the higher voltage is connected to the circuit first and begins supplying power. After the balancing time, the controller controls the first switch Q1 to close. At this time, the first battery 601b with the lower voltage is connected to the circuit and begins supplying power. Because the higher-voltage battery switches power first and the lower-voltage battery switches power later, the voltage difference between the batteries is reduced, thereby reducing the inrush current between the batteries. After the third preset time, the bypass circuit 602 is controlled to operate and the step-down circuit 603 is controlled to stop operating. At this time, the batteries switch from series mode to parallel mode.

[0262] The MOS tube in the battery pack can be in a switching state, that is, the switching tube has two states: open and closed. It can also be in a linear state, that is, the MOS tube is in a linear region. The working state of the MOS tube changes linearly instead of instantaneously, so as to further reduce the impact current. The following is a detailed explanation with reference to the accompanying drawings.

[0263] See also Figure 21 , this figure is another control timing diagram for switching from series mode to parallel mode provided in an embodiment of the present application.

[0264] When the first switch tube Q1 operates in the linear region, the first switch tube Q1 gradually switches from the off state to the on state during the balancing time, thereby reducing the inrush current between the batteries.

[0265] See also Figure 22 , which is a switching simulation diagram without equilibrium time provided in an embodiment of the present application.

[0266] By observing the I(V_a) curve in the figure, it can be found that when switching from series mode to parallel mode, if there is a voltage difference between the batteries, the impact current between them can reach about 10A (that is, the dark gray line in the figure has a clear peak), which will cause damage to the battery.

[0267] See also Figure 23 , this figure is a switching simulation diagram with balance time provided in an embodiment of the present application.

[0268] By observing the I(V_a) curve in the figure, it can be found that after setting the balance time, when switching from series mode to parallel mode, the impact current is about 0.5A (that is, the peak of the dark gray line in the figure is significantly reduced). The impact current reduction effect is obvious and can effectively protect the battery.

[0269] The above system embodiment illustrates the operating principle of the controller when controlling battery mode switching. Specifically, when switching the batteries from series mode to parallel mode, the controller activates the bypass circuit and deactivates the step-down circuit. When switching the batteries from parallel mode to series mode, the controller activates the step-down circuit and deactivates the bypass circuit. This embodiment of the present application also provides another control scheme for the step-down circuit and bypass circuit, which simplifies the control signals and control process. This is described in detail below with reference to the accompanying figures.

[0270] Power supply system embodiment 5:

[0271] The battery pack's output voltage is collected via an ADC (Analog-to-Digital Converter) and transmitted to a controller. When the controller determines that the battery pack's output voltage is above a first preset voltage threshold, the controller activates the step-down circuit and deactivates the bypass circuit. When the controller determines that the battery pack's output voltage is below or equal to the first preset voltage threshold, the controller activates the bypass circuit and deactivates the step-down circuit, thereby achieving automatic switching between the bypass and step-down circuits. This is described in detail below with reference to the accompanying drawings.

[0272] See also Figure 24 , this figure is a schematic diagram of automatic control of a battery working mode provided in an embodiment of the present application.

[0273] The first preset voltage threshold is denoted by Vth. When the output voltage of the battery pack is lower than Vth, the controller controls the bypass circuit 602 to be turned on and controls the buck circuit 603 to be turned off.

[0274] When the output voltage of the battery pack is higher than Vth, the controller controls the bypass circuit 602 to be turned off and the buck circuit 603 to be turned on.

[0275] The first preset voltage threshold is greater than the maximum output voltage of the battery pack in the parallel mode and less than the minimum output voltage of the battery pack in the series mode.

[0276] For example, when the batteries are in parallel mode, the maximum output voltage of the battery pack is approximately 4.2V-4.3V. When the batteries are in series mode, the minimum output voltage of the battery pack is approximately 7.2V, that is, the first battery 601a and the second battery 601b are connected in series, and the output voltage of each battery is approximately 3.6V. The value of the first preset voltage threshold Vth can be greater than the maximum output voltage in parallel and less than the minimum output voltage in series, that is, it satisfies: 7.2V>Vth>4.3V, for example, Vth can be 4.5V. The above values ​​are only examples, different terminal devices may correspond to different battery parameters, and the value of Vth is not specifically limited in this application.

[0277] Furthermore, in order to prevent the output voltage of the battery pack from repeatedly switching between the bypass circuit and the buck circuit due to glitches or voltage oscillations caused by interference, a hysteresis control method is also provided below. For example, when the output voltage of the battery pack is close to the first preset voltage threshold Vth1, there may be voltage glitches when the ADC measures the output voltage of the battery pack, that is, the voltage oscillates due to interference. At this time, the relationship between the output voltage of the battery pack and the first preset voltage threshold Vth1 will be repeatedly changed, which will cause the controller to repeatedly switch between the bypass circuit and the buck circuit. Therefore, the hysteresis voltage interval is increased to reduce the impact of this problem on the power supply system.

[0278] See also Figure 25 , this figure is another automatic control schematic diagram of enabling the bypass circuit and the buck circuit provided in an embodiment of the present application.

[0279] Indicated by Vth1 Figure 24 The first preset voltage threshold in the hysteresis voltage interval is Vth3-Vth2. Among them, Vth2 is greater than Vth1, and Vth1 is greater than Vth3, that is, Vth2>Vth1>Vth3. Vth2 and Vth3 can be set according to actual conditions. Vth2 should be greater than the maximum value of the voltage glitch, and Vth3 should be less than the minimum value of the voltage glitch, thereby suppressing the impact of the voltage glitch during the switching process. That is, the hysteresis voltage interval may include the voltage range of the voltage glitch, and this range can be determined in advance through experimental measurements. For example, when the output voltage of the battery pack is Vth1, the operating modes of the buck circuit and the bypass circuit can be repeatedly switched to obtain the voltage range of the voltage glitch.

[0280] In this embodiment, it is not necessary to compare the relationship between the output voltage and Vth1 , but it is possible to directly compare whether the output voltage is greater than Vth2 and less than Vth3 .

[0281] The controller determines the relationship between the output voltage of the battery pack and Vth2. When the output voltage of the battery pack is less than Vth2, the controller determines that the output voltage of the battery pack is affected by voltage glitches and keeps the current bypass circuit and buck circuit enabled.

[0282] The controller determines the relationship between the output voltage of the battery pack and Vth3. When the output voltage of the battery pack is greater than Vth3, the controller determines that the output voltage of the battery pack is affected by voltage glitches and keeps the current bypass circuit and buck circuit enabled.

[0283] By increasing the hysteresis voltage range, the impact of voltage glitches when the ADC detects the output voltage of the battery pack can be reduced. Furthermore, the impact of voltage glitches can be reduced by adding a debounce time control. For example, after the controller first confirms that the battery has switched modes, it will not switch modes again within a preset time. The embodiment of this application does not specifically limit the length of the preset time.

[0284] The controller of this embodiment determines the working status of the bypass circuit and the buck circuit by comparing the output voltage of the battery pack with a first preset voltage threshold. It can switch the working status of the bypass circuit and the buck circuit even after the working mode of the battery pack is switched, and simplifies the control signal and control process.

[0285] Chip Example 1:

[0286] The buck circuit and bypass circuit in the above embodiment may belong to two different chips respectively. The embodiment of the present application further provides a chip, which includes both the buck circuit and the bypass circuit, which will be described in detail below with reference to the accompanying drawings.

[0287] See also Figure 26 , which is a schematic diagram of a chip provided in an embodiment of the present application.

[0288] The chip includes both a step-down circuit 602 and a bypass circuit 603 .

[0289] One end of the bypass circuit 602 is connected to the input end of the step-down circuit 603 , and the other end of the bypass circuit 602 is connected to the output end of the step-down circuit 603 .

[0290] The bypass circuit 602 and the step-down circuit 603 are both connected to the controller of the terminal device and receive control signals sent by the controller to switch the working state. When the batteries in the battery pack 601 need to be switched to the series mode, the step-down circuit 603 works and the bypass circuit 602 stops working; when the batteries in the battery pack 601 are in the parallel mode, the bypass circuit 602 works and the step-down circuit 603 stops working.

[0291] It can be understood that other descriptions of the controller, buck circuit, bypass circuit, battery pack, etc. in the chip embodiment can refer to the descriptions of other embodiments and will not be repeated here.

[0292] Since the chip includes both the step-down circuit 602 and the bypass circuit 603 , when the power supply system uses the chip, the size of the hardware device can be reduced, thus saving costs.

[0293] Method Example 1:

[0294] Based on the power supply system of the terminal device provided in the above embodiment, an embodiment of the present application also provides a power supply method for the terminal device.

[0295] See also Figure 27 , which is a flow chart of a power supply method for a terminal device provided in an embodiment of the present application.

[0296] This method is applied to a power supply system for a terminal device, comprising a battery pack, a bypass circuit, a step-down circuit, and a controller. The battery pack comprises at least two batteries, the output of which is connected to the input of the step-down circuit, which in turn is connected to a power-consuming component of the terminal device. The bypass circuit is connected across the input and output of the step-down circuit. The operating principle of this power supply system can be found in the aforementioned power supply system embodiments and will not be further described in detail in this embodiment of the present application.

[0297] The method comprises the following steps:

[0298] S2701: When the batteries in the battery pack are in series mode, the step-down circuit is controlled to operate and the bypass circuit is controlled to stop operating.

[0299] S2702: When the batteries in the battery pack are in parallel mode, the bypass circuit is controlled to work and the step-down circuit is controlled to stop working.

[0300] Continue to see Figure 7 The power supply system shown in FIG. 1 is a method for determining whether the battery in the battery pack needs to switch the working mode.

[0301] Method 1: The voltage across the power-consuming element is determined based on the current output voltage of the battery pack, the current flowing through the power-consuming element, and the impedance of each circuit component. If the voltage across the power-consuming element is determined to be lower than a second preset voltage threshold, the battery pack is determined to need to switch from parallel mode to series mode. This second preset voltage threshold can be set to the terminal device's shutdown threshold voltage, for example, 2.6V.

[0302] The voltage across the current-sense resistor in the discharge path can be measured in real time, and the current flowing through the power-consuming element can be determined based on the ratio of the voltage across the current-sense resistor to the impedance of the current-sense resistor.

[0303] In addition, it can be determined that the batteries in the battery pack need to be switched to the series mode according to the output voltage and temperature of the battery pack. The following describes in detail possible implementation methods.

[0304] Method 2: Use a lookup table based on the battery pack's output voltage and temperature to determine whether the batteries in the pack need to be switched to series mode. Specifically, select the table corresponding to the load current. A high-load table is used when the load current is greater than a preset current, and a low-load table is used when the load current is less than or equal to the preset current.

[0305] The voltage across the current-sense resistor in the discharge path can be measured in real time. The ratio of the voltage across the current-sense resistor to the resistance of the current-sense resistor is the load current. The output voltage of the battery pack can be sampled using an ADC. Furthermore, by detecting the resistance of a thermistor, the temperature corresponding to that resistance is determined, and the current battery temperature can be determined. NTC thermistors can be used within the battery.

[0306] In low temperature, low voltage, and heavy load scenarios, the series mode is preferred to prevent abnormal device shutdown; in light load scenarios, the parallel mode is preferred to increase the device's battery life.

[0307] Method 3: To reduce storage space on the terminal device, a preset function f can be used instead of the table in Method 3. The controller substitutes the battery pack's output voltage U and battery temperature T into the preset function f to obtain a function value. When the function value is less than or equal to the preset value, it determines that the batteries in the battery pack need to switch to series connection mode. The function value of the preset function is positively correlated with the battery pack's temperature and the battery pack's output voltage.

[0308] Furthermore, a preset value is selected based on the magnitude of the load current. When the load current is greater than the preset current, the first preset value corresponds to the load current, and when the load current is less than or equal to the preset current, the second preset value corresponds to the load current. The first preset value is smaller than the second preset value. That is, a heavy load scenario corresponds to the first preset value, and a light load scenario corresponds to the second preset value.

[0309] This preset value represents the threshold voltage for switching between series and parallel modes at 0°C. For example, a heavy load scenario corresponds to the first preset value. When the battery voltage is greater than the first preset value, the battery pack should be in parallel mode; when the battery voltage is less than or equal to the first preset value, the battery pack is suitable for series mode.

[0310] The above methods can be used to determine whether the battery pack's operating mode needs to be switched. In addition, a forced switch can be implemented through the terminal device's control interface. For example, a "low temperature mode" can be added to the terminal device's control interface. When the user selects to enter "low temperature mode" and confirms that the low temperature mode button is triggered, the battery pack should switch to series mode. When the user exits "low temperature mode", the power supply system switches to automatic mode, and the power supply system controller automatically selects the most appropriate operating mode.

[0311] Another example is adding a "low power mode" to the terminal device's control interface. When the user actively selects "low power mode" and the low power mode button is triggered, the battery pack should switch to series mode. When the user exits "low power mode," the power supply system switches to automatic mode, and the power supply system controller automatically selects the most appropriate operating mode.

[0312] For detailed description of the above methods, please refer to the second embodiment of the power supply system, which will not be repeated here.

[0313] By using the power supply method for the terminal device provided by the embodiment of the present application, when the batteries in the battery pack are in series mode, the step-down circuit is controlled to work and the bypass circuit is controlled to stop working; it is also possible to control the bypass circuit to work and the step-down circuit to stop working when the batteries in the battery pack are in parallel mode. Therefore, the batteries in the battery pack can be controlled to switch between series mode and parallel mode, and the batteries in the battery pack are controlled to switch from parallel mode to series mode in scenarios such as low ambient temperature (for example, outdoors in winter), low battery power and heavy load, which can greatly reduce the probability of abnormal shutdown of the terminal device, improve the stability of the terminal device when applied in the above scenario, and thus improve the user experience in the above scenario. In scenarios where the ambient temperature is relatively normal, the battery pack has sufficient power and the load is small, the batteries in the battery pack are controlled to switch from series mode to parallel mode to improve the discharge efficiency of the battery pack, extend the battery life of the terminal device, and thus improve the user experience in the above scenario.

[0314] Method Example 2:

[0315] Furthermore, the embodiment of the present application also provides another power supply method for a terminal device, which can smoothly switch the battery pack between the series mode and the parallel mode to reduce the impact of the switching process on the output voltage of the power supply system, thereby improving the stability of the terminal device. Figure 7 The power supply system shown is taken as an example for specific explanation.

[0316] The following first describes the power supply method when the battery pack switches from parallel mode to series mode.

[0317] See also Figure 28 , which is a flow chart of a power supply method when a battery pack provided in an embodiment of the present application switches from a parallel mode to a series mode.

[0318] The method comprises the following steps:

[0319] S2801: First control the step-down circuit to work and the bypass circuit to stop working.

[0320] Continue to see Figure 7In order to prevent the higher voltage output by the batteries directly connected in series from directly impacting the subsequent circuit, the switching of the step-down circuit and the bypass circuit needs to be done before the states of the switching tubes Q1, Q2 and Q3 are switched.

[0321] S2802: Control the first switch tube, the second switch tube, and the third switch tube to be turned off.

[0322] S2803: After the first preset time, the second switch tube is controlled to close.

[0323] To prevent short circuits between the positive and negative electrodes of individual cells during the battery pack's switching operation mode, the switches within the battery pack are not switched simultaneously. Instead, the first and third switches Q1 and Q3 are first controlled to be off, and then the second switch Q2 is controlled to be on after a first preset time. This first preset time can be the dead time of the NMOS transistor. A detailed description of the dead time can be found in the second embodiment of the system described above and will not be repeated here.

[0324] This method achieves smooth switching of the bypass circuit and the buck circuit when the batteries are switched from parallel mode to series mode, reduces the voltage impact of the higher output voltage of the batteries in series on the subsequent circuit, and further improves the stability of the terminal equipment.

[0325] The following describes the power supply method when the battery pack switches from series mode to parallel mode.

[0326] See also Figure 29 , which is a flow chart of a power supply method when a battery pack provided in an embodiment of the present application switches from a series mode to a parallel mode.

[0327] The method comprises the following steps:

[0328] S2901: First, the first switch tube, the second switch tube, and the third switch tube are all controlled to be turned off.

[0329] In order to prevent the higher voltage output by the series-connected batteries from directly impacting the subsequent circuit during the switching process, the switching between the step-down circuit and the bypass circuit needs to be completed after the switching tubes Q1, Q2 and Q3 complete the state switching.

[0330] S2902: After the second preset time, the first switch tube and the third switch tube are controlled to be closed.

[0331] The second preset time may be the dead time of the NMOS transistor. Detailed description of the dead time can be found in the above-mentioned system embodiment 2, which will not be repeated in this embodiment.

[0332] When the batteries are in series mode, due to differences in capacity or self-discharge rates between the batteries, the voltages between the batteries will be unequal. At this time, directly switching to parallel mode will cause excessive inrush current between the batteries, causing damage to the battery cells. In order to alleviate the inrush current, the battery with higher voltage can be connected to the circuit first to start powering. After the balancing time, the controller controls the battery with lower voltage to connect to the circuit to start powering. Since the high-voltage battery switches power supply first and the low-voltage battery switches power supply later, the voltage difference between the batteries is reduced, thereby reducing the inrush current between the batteries.

[0333] This balancing time, also known as the fourth preset time, is determined by the voltage difference between the cells and the internal resistance of each cell. The greater the voltage difference between the cells and the greater the internal resistance of the cells, the longer the balancing time required. If there is no voltage difference between the two cells, no balancing time is required.

[0334] Therefore, controlling the first switch tube and the third switch tube to close after the second preset time is specifically as follows:

[0335] When it is determined that the voltage of the first battery is greater than the voltage of the second battery, the first switch tube is controlled to be closed after the second preset time, and the third switch tube is controlled to be closed after the fourth preset time.

[0336] When it is determined that the voltage of the first battery is lower than the voltage of the second battery, the third switch tube is controlled to be closed after the second preset time, and the first switch tube is controlled to be closed after the fourth preset time.

[0337] When it is determined that the voltage of the first battery is equal to the voltage of the second battery, there is no voltage difference between the two batteries. After the second preset time, the first switch tube and the third switch tube can be controlled to be closed at the same time.

[0338] S2903: After the third preset time, the bypass circuit is controlled to operate and the step-down circuit is controlled to stop operating.

[0339] To prevent a short circuit between the positive and negative electrodes of the battery during the switching process, the switches in the battery pack do not switch simultaneously. Instead, the second switch Q2 is first turned off. After a second preset time, the first and third switches Q1 and Q3 are then turned on. After a third preset time, the bypass circuit is activated and the step-down circuit is deactivated. The sum of the dead time and the third preset time is referred to as the hysteresis time.

[0340] The third preset time needs to be greater than the dead time of the NMOS transistor to ensure that when the controller controls the switching of the buck circuit 603 and the bypass circuit 602 , the first switch tube Q1 and the third switch tube Q3 are already in the on state.

[0341] This power supply method can achieve smooth switching between the bypass circuit and the buck circuit when the batteries are switched from parallel mode to series mode, and also reduces the current impact between the batteries during the switching process, thereby protecting the batteries.

[0342] Terminal device embodiment 1:

[0343] Based on the power supply system of the terminal device provided in the above embodiment, the embodiment of the present application also provides a terminal device, which is described in detail below with reference to the accompanying drawings.

[0344] See also Figure 30 , which is a schematic diagram of a terminal device provided in an embodiment of the present application.

[0345] The terminal device 3000 includes a power supply system 3001 and a power-consuming component 3002. The power supply system 3001 comprises a battery pack, a bypass circuit, a step-down circuit, and a controller. The battery pack includes at least two batteries, the output of which is connected to the input of the step-down circuit, which in turn is connected to the power-consuming component of the terminal device. The bypass circuit has two terminals connected across the input and output of the step-down circuit.

[0346] The working principle of the power supply system can be found in the above-mentioned terminal system embodiments, and will not be described in detail in this embodiment.

[0347] The power supply system of the terminal device includes a controller, which controls the step-down circuit to operate and the bypass circuit to stop operating when the batteries in the battery pack are in series mode; it can also control the bypass circuit to operate and the step-down circuit to stop operating when the batteries in the battery pack are in parallel mode, and can control the batteries in the battery pack to switch between series mode and parallel mode. In scenarios such as low ambient temperature (such as outdoors in winter), low battery pack power, and heavy load, the controller controls the batteries in the battery pack to switch from parallel mode to series mode, which can greatly reduce the probability of abnormal shutdown of the terminal device, improve the stability of the terminal device when used in the above scenarios, and thus improve the user experience in the above scenarios. In scenarios where the ambient temperature is relatively normal, the battery pack power is sufficient, and the load is small, the controller controls the batteries in the battery pack to switch from series mode to parallel mode to improve the discharge efficiency of the battery pack, extend the battery life of the terminal device, and thus improve the user experience in the above scenarios.

[0348] The type and application scenario of the terminal device are not specifically limited in the embodiments of the present application. It can be a foldable screen mobile phone or other terminal device with a battery.

[0349] It should be understood that in the embodiments of the present application, "at least one (item)" means one or more, and "more than one" means two or more. "And / or" indicates that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist, where A and B can be singular or plural.

[0350] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A power supply system for a terminal device, characterized in that: include: A battery pack, a bypass circuit, a step-down circuit, and a controller; the battery pack includes at least two batteries; The output end of the battery pack is connected to the input end of the step-down circuit, and the output end of the step-down circuit is connected to the power-consuming element of the terminal device; one end of the bypass circuit is connected to the input end of the step-down circuit, and the other end of the bypass circuit is connected to the output end of the step-down circuit; The controller is configured to control the step-down circuit to operate and the bypass circuit to stop operating when the batteries in the battery pack need to be switched to a series mode; and is further configured to control the bypass circuit to operate and the step-down circuit to stop operating when the batteries in the battery pack need to be switched to a parallel mode; The controller is configured to control the step-down circuit to operate and the bypass circuit to stop operating, including: when the controller determines that the output voltage of the battery pack is greater than or equal to a first preset voltage threshold, controlling the step-down circuit to operate and controlling the bypass circuit to stop operating, wherein the first preset voltage threshold is greater than the maximum output voltage of the battery pack in parallel mode and less than the minimum output voltage of the battery pack in series mode; The controller is further configured to determine that the batteries in the battery pack need to be switched to a series connection mode when it is determined that the voltage across the power-consuming element is lower than a second preset voltage threshold.

2. The power supply system according to claim 1, characterized in that: The controller is further configured to determine, based on the output voltage of the battery pack and the temperature of the battery pack, that the batteries in the battery pack need to be switched to a series mode.

3. The power supply system according to claim 2, characterized in that: The controller is further configured to determine, by looking up a table according to the output voltage of the battery pack and the temperature of the battery pack, that the batteries in the battery pack need to be switched to a series mode.

4. The power supply system according to claim 3, characterized in that: The controller selects a table corresponding to the load current according to the load current. When the load current is greater than a preset current, the controller selects a table corresponding to a large load table. When the load current is less than or equal to the preset current, the controller selects a table corresponding to a small load table.

5. The power supply system according to claim 2, characterized in that: The controller is further configured to obtain a corresponding value based on the output voltage of the battery pack and the temperature of the battery pack, and determine that the batteries in the battery pack need to be switched to a series mode when the value is less than or equal to a preset value.

6. The power supply system according to claim 2, characterized in that: The controller is used to obtain a function value using a preset function to obtain the output voltage of the battery pack and the temperature of the battery pack as the numerical value. When the function value is less than or equal to the preset value, it is determined that the batteries in the battery pack need to be switched to series mode; the function value of the preset function is positively correlated with the temperature of the battery pack, and the function value of the preset function is positively correlated with the output voltage of the battery pack.

7. The power supply system according to any one of claims 1 to 6, characterized in that: The controller is further configured to determine that the batteries in the battery pack need to be switched to a series mode when it is determined that the low temperature mode button is triggered.

8. The power supply system according to any one of claims 1 to 6, characterized in that: The controller is further configured to determine that the batteries in the battery pack need to be switched to a series mode when it is determined that the power level of the battery pack is lower than a preset power level or when it is determined that a low power mode button is triggered.

9. The power supply system according to any one of claims 1 to 6, characterized in that: The battery pack includes at least two batteries: a first battery and a second battery; the battery pack also includes: a first switching tube, a second switching tube and a third switching tube; The positive electrode of the first battery is connected to the input end of the step-down circuit; The negative electrode of the first battery is connected to the positive electrode of the second battery through the second switch tube, and the negative electrode of the second battery is grounded; One end of the first switch tube is connected to the negative electrode of the first battery, and the other end of the first switch tube is grounded; One end of the third switch tube is connected to the input end of the step-down circuit, and the other end of the third switch tube is connected to the positive electrode of the second battery; When the battery needs to be switched to a series mode, the controller controls the first switch tube and the third switch tube to be disconnected, and controls the second switch tube to be closed; when the battery needs to be switched to a parallel mode, the controller controls the second switch tube to be disconnected, and controls the first switch tube and the third switch tube to be closed.

10. The power supply system according to claim 9, characterized in that: The battery pack further comprises: a first capacitor; a first end of the first capacitor is connected to the output end of the battery pack, and a second end of the first capacitor is grounded; When the batteries need to be switched to the series mode, the controller controls the first switch tube and the third switch tube to be disconnected and controls the second switch tube to be closed, including: When the batteries in the battery pack need to be switched to a series mode, the controller controls the first switch tube, the second switch tube, and the third switch tube to be disconnected, and controls the second switch tube to be closed after a first preset time.

11. The power supply system according to claim 10, characterized in that: Also includes: A second capacitor; a first end of the second capacitor is connected to the output end of the step-down circuit, and a second end of the second capacitor is grounded.

12. The power supply system according to claim 10 or 11, characterized in that: When the batteries need to be switched to the parallel mode, the bypass circuit is controlled to operate and the step-down circuit is controlled to stop operating. When the batteries need to be switched to the parallel mode, the controller controls the second switch tube to be disconnected and the first switch tube and the third switch tube to be closed, including: When the battery needs to switch to the parallel mode, the controller controls the first switch tube, the second switch tube and the third switch tube to be disconnected. After a second preset time, the controller controls the first switch tube and the third switch tube to be closed. After a third preset time, the controller controls the bypass circuit to operate and controls the step-down circuit to stop operating.

13. The power supply system according to claim 12, wherein: After the second preset time, the controller controls the first switch tube and the third switch tube to be closed, including: When the controller determines that the voltage of the first battery is greater than the voltage of the second battery, the controller controls the first switch to close after the second preset time, and controls the third switch to close after a fourth preset time; or When the controller determines that the voltage of the first battery is lower than the voltage of the second battery, the controller controls the third switch to close after the second preset time, and controls the first switch to close after the fourth preset time; or When the controller determines that the voltage of the first battery is equal to the voltage of the second battery, the controller controls the first switch tube and the third switch tube to be closed after a second preset time.

14. A chip, characterized in that: include: Bypass circuit and step-down circuit; The input end of the step-down circuit is connected to the output end of the battery pack, and the output end of the step-down circuit is connected to the power-consuming element of the terminal device; One end of the bypass circuit is connected to the input end of the step-down circuit, and the other end of the bypass circuit is connected to the output end of the step-down circuit; The bypass circuit and the step-down circuit are both connected to a controller of the terminal device. When the batteries in the battery pack need to be switched to a series mode, the step-down circuit operates in response to a control signal from the controller, and the bypass circuit stops operating. When the batteries in the battery pack are in a parallel mode, the bypass circuit operates in response to a control signal from the controller, and the step-down circuit stops operating. The series mode is determined to need to be switched when the voltage across the power-consuming element is lower than a second preset voltage threshold. Wherein, in response to the control signal of the controller, the step-down circuit operates and the bypass circuit stops operating, comprising: In response to the output voltage of the battery pack being greater than or equal to a first preset voltage threshold, the step-down circuit operates and the bypass circuit stops operating, wherein the first preset voltage threshold is greater than the maximum output voltage of the battery pack in parallel mode and less than the minimum output voltage of the battery pack in series mode.

15. A power supply method for a terminal device, characterized in that: A power supply system for a terminal device, the power supply system comprising: a battery pack, a bypass circuit, a step-down circuit, and a controller; the battery pack comprising at least two batteries; an output end of the battery pack connected to an input end of the step-down circuit, and an output end of the step-down circuit connected to a power-consuming element of the terminal device; one end of the bypass circuit connected to the input end of the step-down circuit, and the other end of the bypass circuit connected to the output end of the step-down circuit; When it is determined that the voltage across the power consumption element is lower than a second preset voltage threshold, determining that the batteries in the battery pack need to be switched to a series mode; When the batteries in the battery pack are in series connection mode, controlling the step-down circuit to operate and controlling the bypass circuit to stop operating; When the batteries in the battery pack are in parallel mode, controlling the bypass circuit to operate and controlling the step-down circuit to stop operating; Among them, when the batteries in the battery pack are in series mode, the step-down circuit is controlled to work and the bypass circuit is controlled to stop working, including: when it is determined that the output voltage of the battery pack is greater than or equal to a first preset voltage threshold, the step-down circuit is controlled to work and the bypass circuit is controlled to stop working, and the first preset voltage threshold is greater than the maximum output voltage of the battery pack in parallel mode and less than the minimum output voltage of the battery pack in series mode.

16. The power supply method according to claim 15, characterized in that: Also includes: It is determined, according to the output voltage of the battery pack and the temperature of the battery pack, that the batteries in the battery pack need to be switched to a series connection mode.

17. The power supply method according to claim 16, wherein: Determining, according to the output voltage of the battery pack and the temperature of the battery pack, that the batteries in the battery pack need to be switched to a series mode includes: By looking up a table according to the output voltage of the battery pack and the temperature of the battery pack, it is determined that the batteries in the battery pack need to be switched to a series connection mode.

18. The power supply method according to claim 17, wherein: Also includes: A table corresponding to the load current is selected according to the load current. When the load current is greater than a preset current, a large load table corresponds to the table. When the load current is less than or equal to the preset current, a small load table corresponds to the table.

19. A terminal device, characterized in that: The power supply system according to any one of claims 1 to 13 further comprises: a power-consuming element; The power supply system is used to supply power to the power-consuming components.

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