Power supply circuit applied to series connection of batteries and power supply detection method

Abstract

The invention discloses a power supply circuit applied to battery series connection and a power supply detection method, and the method comprises the steps: obtaining a no-load voltage value of a voltage detection end if a switch control end receives a conduction signal; controlling a load to be connected to two stages of the battery pack, and acquiring a working voltage value of the voltage detection end and a working current value of the current detection end; analyzing the no-load voltage value, the working voltage value and the working current value according to a preset load current analysis rule to obtain a corresponding load current; and according to the working voltage value and the load current, curve parameter matching is carried out with a pre-stored curve database so as to acquire a matched curve parameter as a corresponding electric quantity measurement value. According to the power supply detection method, the no-load voltage value, the working voltage value and the working current value are measured through the power supply controller, curve parameter matching is carried out to obtain the corresponding electric quantity measurement value, and the method can be used for battery series power supply and accurate measurement of the battery electric quantity.

Description

Technical Field

[0001] The present invention relates to the technical field of circuits, and in particular to a power supply circuit and a power supply detection method for batteries connected in series. Background Art

[0002] For terminal products equipped with batteries developed based on the MTK platform (an integrated circuit device development platform), under normal circumstances, since only a single battery is used for power supply, the battery voltage is 3.8V, and the software and hardware of the terminal products are adapted to the voltage of a single battery; when a device with higher power needs to be developed, the voltage of a single battery is insufficient due to the output power, resulting in problems such as fast power consumption, system instability, and high heat generation in the terminal product. At this time, multiple batteries need to be connected in series to increase the battery pack voltage and power the system, but the software and hardware of the terminal product cannot adapt to the voltage of the battery pack and measure the battery power. Therefore, the existing technology has the problem that the terminal product cannot adapt to the battery series power supply and perform power detection. Summary of the invention

[0003] The embodiments of the present invention provide a power supply circuit and a power supply detection method for batteries connected in series, aiming to solve the problem in the prior art that terminal products cannot adapt to batteries connected in series for power supply and power detection.

[0004] In a first aspect, an embodiment of the present invention discloses a power supply detection method for batteries connected in series, the method being used in a power supply controller for a power supply circuit connected in series with batteries, wherein a switch control terminal of the power supply controller is connected to a control switch, a power supply input terminal of the power supply controller is connected to a positive electrode of a battery pack through a step-down circuit, a voltage detection terminal of the power supply controller is connected to a positive electrode of the battery pack through an operational amplifier, two current detection terminals of the power supply controller are respectively connected to two ends of a detection resistor, and the detection resistor is arranged in series between a negative electrode of the battery pack and a ground terminal; the battery pack comprises a plurality of batteries connected in series, and the power supply detection method comprises: If a conduction signal is received through the switch control terminal, a no-load voltage value of the voltage detection terminal is obtained; Controlling the load to access the two stages of the battery pack, and obtaining the working voltage value of the voltage detection end and the working current value of the current detection end; The no-load voltage value, the working voltage value and the working current value are analyzed according to a preset load current analysis rule to obtain a corresponding load current; Curve parameter matching is performed with a pre-stored curve database according to the operating voltage value and the load current to obtain matching curve parameters as corresponding electrical quantity measurement values.

[0005] In a second aspect, an embodiment of the present invention further discloses a power supply circuit for series connection of batteries, wherein a power supply controller of the power supply circuit applies the power supply detection method for series connection of batteries as described in the first aspect above, and the power supply circuit further includes an operational amplifier, a step-down circuit and a detection resistor; The switch control end of the power supply controller is connected to one end of the control switch, and the other end of the control switch is grounded; The power supply input terminal of the power supply controller is connected to the positive pole of the battery pack through a step-down circuit, the voltage detection terminal of the power supply controller is connected to the positive pole of the battery pack through an operational amplifier, and the two current detection terminals of the power supply controller are respectively connected to the two ends of the detection resistor, and the detection resistor is arranged in series between the negative pole of the battery pack and the ground terminal; the battery pack includes a plurality of batteries connected in series.

[0006] The embodiment of the present application discloses a power supply circuit and a power supply detection method for battery series connection, the power supply detection method comprising: if a conduction signal is received through the switch control end, the no-load voltage value of the voltage detection end is obtained; the load is controlled to be connected to the two stages of the battery pack, and the working voltage value of the voltage detection end and the working current value of the current detection end are obtained; the no-load voltage value, the working voltage value and the working current value are analyzed according to the preset load current analysis rules to obtain the corresponding load current; the curve parameters are matched with the pre-stored curve database according to the working voltage value and the load current to obtain the matching curve parameters as the corresponding power measurement value. The above-mentioned power supply detection method measures the no-load voltage value, the working voltage value and the working current value through the power supply controller of the power supply circuit, and matches the curve parameters according to the curve database to obtain the corresponding power measurement value, so that it is suitable for battery series power supply and can accurately measure the battery power. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0008] Figure 1 A method flow chart of a power supply detection method provided by an embodiment of the present invention; Figure 2 An overall circuit structure diagram of a power supply circuit provided by an embodiment of the present invention; Figure 3 A partial circuit structure diagram of a power supply circuit provided in an embodiment of the present invention; Figure 4Another partial circuit structure diagram of the power supply circuit provided in an embodiment of the present invention.

[0009] Figure symbols: U1, power supply controller; U2, charging chip; R1, detection resistor; 1, buck circuit; 2, operational amplifier; U12, buck chip; C125, first capacitor; L5, fifth inductor; C130, second capacitor; R50, first resistor; U7, first operational amplifier chip; U8, second operational amplifier chip; R33, third resistor; R34, fourth resistor; R35, fifth resistor; R100, sixth resistor; C225, third capacitor; C107, fourth capacitor; C7, fifth capacitor; C106, sixth capacitor; S1, control switch; BAT, battery pack. DETAILED DESCRIPTION

[0010] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0011] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0012] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0013] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0014] The embodiment of the present invention discloses a power supply detection method for batteries connected in series, the method is used in a power supply controller for a power supply circuit connected in series with batteries, such as Figure 2As shown, the power supply circuit also includes an operational amplifier 2, a step-down circuit 1 and a detection resistor R1. The switch control end of the power supply controller U1 is connected to the control switch S1. The power supply input end of the power supply controller U1 is connected to the positive electrode of the battery pack BAT through the step-down circuit 1. The voltage detection end of the power supply controller U1 is connected to the positive electrode of the battery pack BAT through the operational amplifier 2. The two current detection ends of the power supply controller U1 are respectively connected to the two ends of the detection resistor R1. The detection resistor R1 is arranged in series between the negative electrode of the battery pack BAT and the ground terminal; the battery pack BAT includes a plurality of batteries connected in series.

[0015] The power supply detection method disclosed in this application is a power supply detection method applied to battery series connection. Figure 1 As shown, the power supply detection method includes steps S110 to S140.

[0016] S110: If a conduction signal is received through the switch control terminal, the no-load voltage value of the voltage detection terminal is obtained.

[0017] The user can operate the control switch to turn on. After the control switch is turned on, the switch control end can receive a turn-on signal. At this time, no load is connected to the power supply circuit. The power supply controller can obtain the voltage value detected by the voltage detection end as the no-load voltage value.

[0018] S120, controlling the load to connect to the two stages of the battery pack, and obtaining the working voltage value of the voltage detection end and the working current value of the current detection end.

[0019] The load is further controlled to be connected to the two stages of the battery pack, and the battery pack supplies power to the load. At the same time, the power supply controller can obtain the voltage value obtained by the voltage detection end again. Since the load is connected to the power supply circuit at this time, the voltage value obtained by the voltage detection end is the working voltage value. Further, the working voltage value can be obtained through the current detection end.

[0020] S130, analyzing the no-load voltage value, the operating voltage value, and the operating current value according to a preset load current analysis rule to obtain a corresponding load current.

[0021] Furthermore, by analyzing the no-load current value, the operating current value and the operating voltage value, the corresponding load current can be obtained. The load current can be analyzed according to the load current analysis rule to obtain the load current, which is also the current value flowing in the current load.

[0022] In a more specific embodiment, step S130 specifically includes the following steps: calculating the resistance of the detection resistor, the operating voltage value and the operating current value according to the first formula in the load current analysis rule to obtain the corresponding battery internal resistance; calculating the battery internal resistance, the operating voltage value and the no-load voltage value according to the second formula in the load current analysis rule to obtain the corresponding load current.

[0023] Specifically, the resistance, working voltage and working current of the detection resistor can be calculated according to the first formula configured in the load current analysis rule, so as to obtain the corresponding internal resistance of the battery. The voltage value of the ungrounded end of the detection resistor can be calculated first, U f =I g ×R 0 ; Among them, I g is the working current value, R 0 is the resistance of the detection resistor, U f is the voltage value of the end of the detection resistor that is not grounded; further, the battery internal resistance R is calculated according to the first formula c =(U 1 -U f )×R 0 / U f Among them, U 1 is the working voltage value, R c is the internal resistance of the battery.

[0024] Furthermore, the battery internal resistance, the operating voltage value and the no-load voltage value can be calculated according to the second formula configured in the load current analysis rule to obtain the corresponding load current. Specifically, the second calculation formula can be expressed as I load =(U 0 -U 1 ) / R c Among them, U 0 is the no-load voltage value, I load is the calculated load current.

[0025] S140, matching curve parameters with a pre-stored curve database according to the operating voltage value and the load current to obtain matching curve parameters as corresponding electric quantity measurement values.

[0026] The curve database stores multiple power detection curves, each of which is a voltage-power curve obtained by testing a specific load. Specifically, the parameter information contained in each power detection curve includes no-load voltage value, working voltage value, consumed battery power value and battery internal resistance.

[0027] For example, for a battery pack composed of two batteries, when the load current is constant at 1A, the data obtained by discharging the battery pack is shown in Table 1; when the load current is constant at other current values ​​(such as 0.4A or 1.6A), the measured data are different. The value of Q (in mAh) in each row of Table 1 represents the cumulative reduction in battery power corresponding to each 1% reduction in power (the battery power corresponding to two adjacent rows differs by 1%).

[0028] Table 1 <![CDATA[U 0 (mV)]]> <![CDATA[U 1 (mV)]]> Q (mAh) <![CDATA[R c (mΩ)]]> 8587 0 135 8560 8475 63 135 8535 8448 126 138 8512 8424 189 140 8489 8401 252 140 8467 8378 315 141 8445 8356 378 141 8423 8334 141 141 8402 8312 504 143 8380 8291 567 141 8359 8270 630 141 8338 8249 693 141 8317 8228 756 141 8296 8204 819 146 8276 8184 882 146 Since an operational amplifier is used in the embodiment of the present application to step down the voltage of the battery pack, the no-load voltage value U in Table 1 actually measured by the power supply controller is 0 '= U 0 / 2, the actual working voltage value U measured by the power supply controller 1 '= U 1 / 2, the actual internal resistance of a single battery is R c '= R c / 2; a two-dimensional curve is constructed based on the actually measured working voltage value and the consumed battery power value, or a two-dimensional curve is constructed based on the actually measured no-load voltage value and the consumed battery power value, and the corresponding power detection curve can be obtained.

[0029] By matching the battery detection curve contained in the curve database with the operating voltage value and the load current, the curve parameters on the corresponding battery detection curve can be obtained and finally the power measurement value can be obtained. The power measurement value is also the remaining power of the battery pack measured.

[0030] In a more specific embodiment, step S140 specifically includes the following steps: obtaining a power detection curve in the curve database that matches the load current as a corresponding target curve; obtaining a power measurement value corresponding to a curve point in the target curve that matches the operating voltage value.

[0031] Specifically, the load current can be matched with each power detection curve in the curve database, so as to obtain a power detection curve that matches the load current as the target curve. Further, the curve parameters corresponding to the curve position that matches the working voltage value (or no-load voltage value) in the target curve are obtained, and the corresponding power measurement value is obtained according to the curve parameters. Since the working voltage value is negatively correlated with the consumed battery power value in the power detection curve, and the working voltage value is monotonically decreasing, the unique matching curve position can be obtained in the target curve through the working voltage value and the corresponding power measurement value can be determined. Similarly, since the no-load voltage value is negatively correlated with the consumed battery power value in the power detection curve, and the no-load voltage value is also monotonically decreasing, the no-load voltage value can also be used instead of the working voltage value to match the curve position in the target curve and obtain the power measurement value.

[0032] In a more specific embodiment, obtaining the power measurement value corresponding to the curve position in the target curve that matches the operating voltage value includes: obtaining the consumed battery power value corresponding to the curve position in the target curve that matches the operating voltage value; calculating the remaining proportion corresponding to the consumed battery power value based on the total power to obtain the corresponding power measurement value.

[0033] Specifically, the consumed battery power value corresponding to the curve point that matches the working voltage value in the target curve can be obtained. There is only one curve point that matches the working voltage value obtained from the target curve. After the number of batteries in the battery pack is determined, the total battery power is also uniquely determined; the power difference between the total power and the consumed battery power value can be calculated, and the power difference and the ratio of the total power can be calculated to obtain the remaining proportion of the battery pack power, and the remaining proportion obtained is used as the power measurement value.

[0034] For example, for the battery pack composed of two batteries in the specific embodiment of the present application, the total power is 6300 mAh, and the currently consumed battery power value is 693 mAh. The corresponding remaining proportion can be calculated to be 89%, which is the final power measurement value.

[0035] The embodiment of the present invention further discloses a power supply circuit for series connection of batteries, wherein the power supply circuit applies the power supply detection method for series connection of batteries as described in the above embodiment, such as Figure 2As shown, the power supply circuit also includes an operational amplifier 2, a step-down circuit 1 and a detection resistor R1; the switch control end of the power supply controller U1 is connected to one end of the control switch S1, and the other end of the control switch S1 is grounded; the power supply input end of the power supply controller U1 is connected to the positive electrode of the battery pack BAT through the step-down circuit 1, the voltage detection end of the power supply controller U1 is connected to the positive electrode of the battery pack BAT through the operational amplifier 2, and the two current detection ends of the power supply controller U1 are respectively connected to the two ends of the detection resistor R1, and the detection resistor R1 is arranged in series between the negative electrode of the battery pack BAT and the ground terminal; the battery pack BAT includes a plurality of batteries connected in series.

[0036] In order to achieve the two batteries ( Figure 2 The battery pack BAT composed of the battery CELL1 and the battery CELL2 shown in the figure is connected in series for power supply detection. The buck circuit 1 can be set to reduce the voltage of the battery pack BAT of about 7.6V to about 3.7V, and then power the system through the VSYS port (that is, the power supply input terminal of the power supply controller U1). The two current detection terminals of the power supply controller U1 are respectively connected to the two ends of the detection resistor R1, that is, the SENSEP port and the SENSEN port are used as two current detection terminals to detect the current value flowing in the detection resistor R1. Operational amplifier 2 is a voltage follower circuit, the purpose of which is to reduce the positive voltage of the battery pack BAT so that the voltage drops to half of the original voltage, and output it to the VBATSENSE port (that is, the voltage detection terminal of the power supply controller U1) so that the power supply controller U1 can detect the positive voltage of the battery pack BAT. The detection resistor R1 is used to detect the current value in the battery power circuit in the main circuit, and the resistance value of the detection resistor R1 is a fixed value.

[0037] like Figure 3 As shown, the buck circuit 1 includes a buck chip U12, a first capacitor C125 and a fifth inductor L5; the second pin of the buck chip U12 is connected to the positive electrode of the battery pack BAT; the sixth pin of the buck chip U12 is connected to one end of the fifth inductor L5, and the other end of the fifth inductor L5 is connected to the power supply input end of the power supply controller U1; the first capacitor C125 is arranged in parallel between the second pin of the buck chip U12 and the ground terminal. Further, the buck circuit 1 also includes a second capacitor C130 and a first resistor R50; the second capacitor C130 and the first resistor R50 are both arranged in parallel between the other end of the fifth inductor L5 and the ground terminal.

[0038] Specifically, the buck circuit 1 is composed of a buck chip U12, a first capacitor C125 and a fifth inductor L5; wherein the first capacitor C125 is used to isolate the second pin of the buck chip U12 from the ground terminal, thereby improving the isolation of the second pin; to increase the actual use effect, multiple capacitors can be set in parallel with the first capacitor C125. The fifth inductor L5 is connected to the sixth pin, thereby filtering the voltage output by the sixth pin to reduce the noise in the voltage signal and improve the reliability of power supply to the system. Similarly, a second capacitor C130 can be set to increase the isolation between the fifth inductor L5 and the ground terminal. To increase the actual use effect, multiple capacitors can be set in parallel with the second capacitor C130; current limiting is performed by setting the first resistor R50, thereby achieving overcurrent protection.

[0039] like Figure 4 As shown, the operational amplifier 2 includes a first operational amplifier chip U7, a second operational amplifier chip U8, a third resistor R33, a fourth resistor R34, a fifth resistor R35, a sixth resistor R100, a third capacitor C225 and a fourth capacitor C107; the third pin of the first operational amplifier chip U7 and one end of the third resistor R33 are both connected to the positive electrode of the battery pack BAT; the first pin of the first operational amplifier chip U7 is grounded, and the second pin of the first operational amplifier chip U7 is connected to the fifth pin of the second operational amplifier chip U8; the other end of the third resistor R33 is connected to the first pin of the second operational amplifier chip U8, the first pin of the first operational amplifier chip U8, and the fifth pin of the second operational amplifier chip U8. One end of the fourth resistor R34 and one end of the third capacitor C225, the second pin of the second operational amplifier chip U8 is connected to the other end of the fourth resistor R34 and the other end of the third capacitor C225 and is grounded; the fifth resistor R35 is arranged in series between the third pin and the fourth pin of the second operational amplifier chip U8, and the fourth pin of the second operational amplifier chip U8 is also connected to one end of the sixth resistor R100; the other end of the sixth resistor R100 is connected to one end of the fourth capacitor C107, and the connection point is connected to the voltage detection end of the power supply controller U1; the other end of the fourth capacitor C107 is grounded. Wherein, the operational amplifier 2 also includes a fifth capacitor C7 and a sixth capacitor C106; one end of the fifth capacitor C7 is connected to the second pin of the first operational amplifier chip U7, and the other end of the fifth capacitor C7 is grounded; one end of the sixth capacitor C106 is connected to the third pin of the first operational amplifier chip U7, and the other end of the sixth capacitor C106 is grounded.

[0040] The operational amplifier 2 is mainly composed of a first operational amplifier chip U7 and a second operational amplifier chip U8. The first operational amplifier chip U7 steps down the positive voltage of the battery pack BAT to 5V, and inputs it to the fifth pin of the second operational amplifier chip U8 to power the second operational amplifier chip U8; further, the second operational amplifier chip U8 steps down the voltage input from the first pin to half of the positive voltage of the battery pack BAT and outputs it from the fourth pin of the second operational amplifier chip U8.

[0041] More specifically, the power supply circuit further includes a charging chip U2, which is arranged in series between the positive electrode of the battery pack BAT and the charging input port. Furthermore, the charging chip U2 can be arranged in series on the positive electrode of the battery pack BAT, and the charging chip U2 steps down the voltage input from the charging input port to a charging voltage and inputs it into the positive electrode of the battery pack BAT, thereby charging the battery pack BAT.

[0042] The present invention discloses a power supply circuit and a power supply detection method for battery series connection, the power supply detection method comprising: if a conduction signal is received through a switch control end, the no-load voltage value of the voltage detection end is obtained; the load is controlled to be connected to the two stages of the battery pack, and the working voltage value of the voltage detection end and the working current value of the current detection end are obtained; the no-load voltage value, the working voltage value and the working current value are analyzed according to a preset load current analysis rule to obtain the corresponding load current; the curve parameters are matched with a pre-stored curve database according to the working voltage value and the load current, so as to obtain matching curve parameters as the corresponding power measurement value. The above-mentioned power supply detection method measures the no-load voltage value, the working voltage value and the working current value through the power supply controller of the power supply circuit, and matches the curve parameters according to the curve database to obtain the corresponding power measurement value, so that it is suitable for battery series power supply and can accurately measure the battery power.

[0043] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A power supply detection method for batteries connected in series, the method being used in a power supply controller for a power supply circuit for batteries connected in series, characterized in that: The switch control terminal of the power supply controller is connected to the control switch, the power supply input terminal of the power supply controller is connected to the positive electrode of the battery pack through a step-down circuit, the voltage detection terminal of the power supply controller is connected to the positive electrode of the battery pack through an operational amplifier, and the two current detection terminals of the power supply controller are respectively connected to the two ends of the detection resistor, and the detection resistor is arranged in series between the negative electrode of the battery pack and the ground terminal; the battery pack includes a plurality of batteries connected in series, and the power supply detection method includes: If a conduction signal is received through the switch control terminal, a no-load voltage value of the voltage detection terminal is obtained; Controlling the load to access the two stages of the battery pack, and obtaining the working voltage value of the voltage detection end and the working current value of the current detection end; The no-load voltage value, the working voltage value and the working current value are analyzed according to a preset load current analysis rule to obtain a corresponding load current; Curve parameter matching is performed with a pre-stored curve database according to the operating voltage value and the load current to obtain matching curve parameters as corresponding electrical quantity measurement values.

2. The power supply detection method for battery series connection according to claim 1, characterized in that: The step of parsing the no-load voltage value, the working voltage value, and the working current value according to a preset load current parsing rule to obtain a corresponding load current includes: Calculating the resistance value of the detection resistor, the operating voltage value, and the operating current value according to the first formula in the load current analysis rule to obtain a corresponding battery internal resistance; The battery internal resistance, the operating voltage value and the no-load voltage value are calculated according to the second formula in the load current analysis rule to obtain the corresponding load current.

3. The power supply detection method for battery series connection according to claim 1 or 2, characterized in that: The matching of curve parameters with a pre-stored curve database according to the operating voltage value and the load current to obtain matching curve parameters as corresponding electric quantity measurement values ​​includes: Acquire a power detection curve in the curve database that matches the load current as a corresponding target curve; Obtain a power measurement value corresponding to a curve point in the target curve that matches the operating voltage value.

4. The power supply detection method for battery series connection according to claim 3 is characterized in that: The obtaining of the electric quantity measurement value corresponding to the curve position matching the operating voltage value in the target curve includes: Obtaining a consumed battery power value corresponding to a curve point in the target curve that matches the operating voltage value; The remaining proportion corresponding to the consumed battery power value is calculated according to the total power to obtain the corresponding power measurement value.

5. A power supply circuit for batteries connected in series, characterized in that: The power supply controller of the power supply circuit applies the power supply detection method for series connection of batteries as described in any one of claims 1 to 4, and the power supply circuit further includes an operational amplifier, a step-down circuit and a detection resistor; The switch control end of the power supply controller is connected to one end of the control switch, and the other end of the control switch is grounded; The power supply input terminal of the power supply controller is connected to the positive pole of the battery pack through a step-down circuit, the voltage detection terminal of the power supply controller is connected to the positive pole of the battery pack through an operational amplifier, and the two current detection terminals of the power supply controller are respectively connected to the two ends of the detection resistor, and the detection resistor is arranged in series between the negative pole of the battery pack and the ground terminal; the battery pack includes a plurality of batteries connected in series.

6. The power supply circuit for batteries in series according to claim 5, characterized in that: The step-down circuit includes a step-down chip, a first capacitor and a fifth inductor; The second pin of the buck chip is connected to the positive electrode of the battery pack; the sixth pin of the buck chip is connected to one end of the fifth inductor, and the other end of the fifth inductor is connected to the power supply input end of the power supply controller; the first capacitor is arranged in parallel between the second pin of the buck chip and the ground end.

7. The power supply circuit for batteries in series according to claim 6, characterized in that: The step-down circuit further includes a second capacitor and a first resistor; The second capacitor and the first resistor are both connected in parallel between the other end of the fifth inductor and the ground.

8. The power supply circuit for batteries in series according to claim 5, characterized in that: The operational amplifier comprises a first operational amplifier chip, a second operational amplifier chip, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor and a fourth capacitor; The third pin of the first operational amplifier chip and one end of the third resistor are both connected to the positive electrode of the battery pack; the first pin of the first operational amplifier chip is grounded, and the second pin of the first operational amplifier chip is connected to the fifth pin of the second operational amplifier chip; The other end of the third resistor is connected to the first pin of the second operational amplifier chip, one end of the fourth resistor and one end of the third capacitor, and the second pin of the second operational amplifier chip is connected to the other end of the fourth resistor and the other end of the third capacitor and is grounded; The fifth resistor is arranged in series between the third pin and the fourth pin of the second operational amplifier chip, and the fourth pin of the second operational amplifier chip is also connected to one end of the sixth resistor; the other end of the sixth resistor is connected to one end of the fourth capacitor, and the connection point is connected to the voltage detection end of the power supply controller; the other end of the fourth capacitor is grounded.

9. The power supply circuit for batteries in series according to claim 8, characterized in that: The operational amplifier further includes a fifth capacitor and a sixth capacitor; One end of the fifth capacitor is connected to the second pin of the first operational amplifier chip, and the other end of the fifth capacitor is grounded; One end of the sixth capacitor is connected to the third pin of the first operational amplifier chip, and the other end of the sixth capacitor is grounded.

10. The power supply circuit for batteries in series according to claim 5, characterized in that: The power supply circuit also includes a charging chip, which is arranged in series between the positive electrode of the battery pack and the charging input port.

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