A battery internal resistance measurement system and method based on sine wave discharge

Abstract

The present invention discloses a battery internal resistance measurement system and method based on sinusoidal discharge, comprising: a microcontroller outputs an original sinusoidal signal with a frequency of 1KHZ; a constant current discharge circuit uses the original sinusoidal signal as a reference waveform to make the discharge waveform of the battery to be measured a sinusoidal wave; an AC coupling amplifier circuit amplifies the internal resistance voltage signal by a preset multiple to obtain an amplified signal; an analog multiplier performs a multiplication operation on the original sinusoidal signal and the amplified signal, and transmits the obtained integrated signal to the microcontroller; the two ends of the sampling resistor are connected to the microcontroller in a differential input mode; the microcontroller also collects the current signal passing through the sampling resistor, and obtains the current amplitude of the current signal at 1KHZ; the microcontroller also collects the voltage amplitude of the DC component of the integrated signal, and determines the internal resistance of the battery to be measured according to the voltage amplitude of the DC component, the preset multiple and the current amplitude at 1KHZ. The present invention can filter out the electromagnetic induction voltage and accurately measure and control the real battery AC part internal resistance.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a battery internal resistance measurement system and method based on sinusoidal wave discharge. Background Art

[0002] At present, many industrial sites use rechargeable batteries as uninterruptible power supplies. Batteries are widely used in communication, automobile, computer and power generation systems. Reasonable use and maintenance of batteries to keep them in good operating condition is the key to extending battery life and improving DC system reliability. The internal resistance of a battery is an important parameter to judge the state of a battery. Therefore, in the process of battery maintenance, it is often necessary to monitor the change of the internal resistance of the battery to judge the quality of the battery.

[0003] There are three existing methods for measuring the internal resistance of batteries. The first is the DC discharge measurement method, which is to discharge the battery with a DC current of a certain magnitude, and then measure the DC voltage difference between the positive and negative poles of the battery. The signal processing unit amplifies the DC signal and sends it to the operation unit, and the internal resistance R is calculated according to the physical formula R=U / I. The second is the DC internal resistance pulse internal resistance measurement method, which uses a small current and a certain frequency of pulse discharge, removes the DC signal through a bandpass filter, and then measures the pulse voltage difference between the positive and negative poles of the battery. After the signal processing unit amplifies the pulse signal, the operation unit calculates the internal resistance R according to the physical formula R=U / I. The third is the AC injection measurement method, which regards the battery as an active resistor, injects a fixed frequency and constant current at both ends of the battery, samples the voltage at both ends of the battery, and calculates the internal resistance of the battery.

[0004] Due to the presence of signal interference and induced voltage during the internal resistance test, the existing measurement methods are unable to accurately measure and control the actual internal resistance of the battery AC part. Summary of the invention

[0005] The present invention provides a battery internal resistance measurement system and method based on sinusoidal wave discharge, which can filter out electromagnetic induction voltage and accurately measure and control the real battery AC part internal resistance.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] In a first aspect, the present invention provides a battery internal resistance measurement system based on sinusoidal wave discharge, the system comprising a microcontroller, a constant current discharge circuit, an AC coupling amplifier circuit, an analog multiplier, a sampling resistor and a DC blocking capacitor;

[0008] The microcontroller is used to output an original sinusoidal signal with a frequency of 1KHZ;

[0009] The constant current discharge circuit, the sampling resistor and the battery to be tested are connected in series to form a battery discharge loop; the constant current discharge circuit uses the original sinusoidal signal as a reference waveform to make the discharge waveform of the battery to be tested a sinusoidal wave;

[0010] The two electrodes of the battery to be tested are respectively connected to the AC coupling amplifier circuit through one of the DC blocking capacitors, so that the internal resistance voltage signal of the battery to be tested is coupled to the AC coupling amplifier circuit;

[0011] The AC coupling amplifier circuit is used to amplify the internal resistance voltage signal by a preset multiple to obtain an amplified signal;

[0012] The analog multiplier is used to perform a multiplication operation on the original sinusoidal signal and the amplified signal, and transmit the obtained composite signal to the microcontroller; the composite signal includes a DC component and an AC component with a frequency twice that of the original sinusoidal signal, the DC component has the same frequency as the AC component and the phase difference is zero;

[0013] The two ends of the sampling resistor are connected to the microcontroller in a differential input manner;

[0014] The microcontroller is also used to collect the current signal passing through the sampling resistor and obtain the current amplitude of the current signal at 1KHZ;

[0015] The microcontroller is also used to collect the voltage amplitude of the DC component of the integrated signal, and determine the internal resistance of the battery to be tested according to the voltage amplitude of the DC component, the preset multiple and the current amplitude at 1KHZ.

[0016] In a possible implementation, collecting the current signal passing through the sampling resistor and obtaining the current amplitude of the current signal at 1 kHz specifically includes:

[0017] In each sampling period, 2 n sampling points, for each sampling point, simultaneously collecting the voltage change at both ends of the sampling resistor; the amplitude of the current signal corresponding to each sampling point is the ratio of the voltage change at the sampling point to the resistance value of the sampling resistor, and n≥8;

[0018] Regarding the 2 n After Fourier transform of each sampling point, the voltage amplitude corresponding to 1KHZ is obtained;

[0019] The current amplitude at 1 kHz is obtained according to the ratio of the voltage amplitude corresponding to 1 kHz to the resistance value of the sampling resistor.

[0020] In a possible implementation, the voltage amplitude of the DC component of the integrated signal is collected, specifically:

[0021] The AC component in the integrated signal is filtered out by a low-pass filter arranged in the microcontroller to obtain a DC component, and the voltage amplitude of the DC component is acquired.

[0022] In a possible implementation manner, collecting the voltage amplitude of the DC component of the integrated signal specifically includes:

[0023] In each sampling period, 2 n sampling points, collecting the voltage amplitude of the integrated signal at each sampling point;

[0024] Regarding the 2 n After Fourier transformation of the sampling points, the zero-frequency amplitude is obtained; the zero-frequency amplitude is the voltage amplitude of the DC component.

[0025] In a possible implementation, the voltage amplitude of the DC component, the preset multiple, and the current amplitude at 1 kHz are used to determine the internal resistance of the battery to be tested, specifically:

[0026] Determining a target voltage amplitude according to a ratio of the voltage amplitude of the DC component to the preset multiple;

[0027] Determine the internal resistance of the battery to be tested according to the ratio of the target voltage amplitude to the current amplitude at 1KHZ

[0028] In a possible implementation, a follower is also included;

[0029] The input end of the follower is connected to the microcontroller, and the output end of the follower is connected to the input end of the constant current discharge circuit and the input end of the analog multiplier; the follower is used to improve the load capacity of the original sinusoidal signal.

[0030] In a possible implementation, the constant current discharge circuit includes an operational amplifier and a MOS tube;

[0031] The in-phase input terminal of the operational amplifier is connected to the microcontroller for receiving the original sinusoidal signal, the inverting input terminal of the operational amplifier is connected to the source of the MOS tube, and the output terminal of the operational amplifier is connected to the gate of the MOS tube;

[0032] The drain of the MOS tube is connected to the positive electrode of the battery to be tested, and the source of the MOS tube is connected to the negative electrode of the battery to be tested through the sampling resistor.

[0033] In a possible implementation, the AC coupling amplifier circuit includes an instrumentation amplifier;

[0034] The positive electrode of the signal input terminal of the instrument amplifier is connected to the negative electrode of the battery to be tested through the DC blocking capacitor, the negative electrode of the signal input terminal of the instrument amplifier is connected to the positive electrode of the battery to be tested through the DC blocking capacitor, and the output terminal of the instrument amplifier is connected to the input terminal of the analog multiplier.

[0035] In a second aspect, the present invention provides a measurement method of a battery internal resistance measurement system based on sinusoidal wave discharge, which is applied to a microcontroller of a battery internal resistance measurement system based on sinusoidal wave discharge as described above, and the measurement method comprises:

[0036] Output frequency is 1KHZ original sinusoidal signal;

[0037] In the process of the constant current discharge circuit using the original sinusoidal signal as a reference waveform to control the battery to be tested to output a sinusoidal discharge waveform, collecting a current signal passing through the sampling resistor, and obtaining a current amplitude of the current signal at 1 kHz;

[0038] The voltage amplitude of the DC component of the integrated signal output by the analog multiplier is collected; the integrated signal is obtained by multiplying the original sinusoidal signal by the original sinusoidal signal in the analog multiplier after the internal resistance voltage signal is amplified by the AC coupling amplifier circuit by a preset multiple and the amplified signal is obtained;

[0039] The internal resistance of the battery to be tested is determined according to the voltage amplitude of the DC component, the preset multiple and the current amplitude at 1 kHz.

[0040] In a third aspect, the present invention provides an electronic device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the measurement method of the battery internal resistance measurement system based on sinusoidal wave discharge.

[0041] In a fourth aspect, the present invention provides a computer-readable storage medium, which stores at least one instruction, at least one program, a code set or an instruction set. The at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by a processor to implement the measurement method of the battery internal resistance measurement system based on sinusoidal wave discharge.

[0042] In actual application, the battery internal resistance measurement system based on sinusoidal wave discharge provided by the embodiment of the present invention outputs an original sinusoidal signal with a frequency of 1KHZ through a microcontroller; the discharge waveform of the battery to be tested is made into a sinusoidal wave by taking the original sinusoidal signal as a reference waveform through a constant current discharge circuit, and it can be known from the discharge waveform that the electromagnetic induction voltage is 90 degrees out of phase with the original sinusoidal signal; the internal resistance voltage signal of the battery to be tested is coupled to the amplifier circuit through a DC blocking capacitor, so as to amplify the original sinusoidal signal by a preset multiple to obtain an amplified signal; the original sinusoidal signal and the amplified signal are multiplied by an analog multiplier to obtain a composite signal, and the composite signal is transmitted to the microcontroller, wherein the composite signal The signal includes a DC component and an AC component twice that of the original sinusoidal signal, and the frequency of the DC component and the AC component are the same and the phase difference is zero; the current signal passing through the sampling resistor is obtained by a microcontroller in a differential sampling manner, and the current amplitude of the current signal at 1KHZ is obtained; the voltage amplitude of the DC component in the integrated signal is collected by the microcontroller, and the internal resistance of the battery to be tested is determined according to the voltage amplitude of the DC component, a preset multiple and the current amplitude at 1KHZ; the present invention realizes synchronous detection operation by cooperating with an analog multiplier and a microcontroller, eliminates the influence of the electromagnetic induction voltage on the battery internal resistance test result, and thus accurately measures and controls the real battery AC part internal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 An overall implementation principle diagram of a battery internal resistance measurement system based on sinusoidal wave discharge provided by an embodiment of the present invention;

[0044] Figure 2 A circuit diagram of a constant current discharge circuit of a battery internal resistance measurement system based on sinusoidal wave discharge provided by an embodiment of the present invention;

[0045] Figure 3 A circuit diagram of an AC coupling amplifier circuit of a battery internal resistance measurement system based on sinusoidal wave discharge provided by an embodiment of the present invention;

[0046] Figure 4 A schematic diagram of synchronous detection operation of an analog multiplier of a battery internal resistance measurement system based on sinusoidal discharge provided by an embodiment of the present invention;

[0047] Figure 5 A flow chart of the steps of a measurement method of a battery internal resistance measurement system based on sinusoidal wave discharge provided in an embodiment of the present invention.

[0048] Reference numerals and description of the drawings:

[0049] 11. Microcontroller; 12. Constant current discharge circuit; 121. Operational amplifier; 122. MOS tube; 13. AC coupling amplifier circuit; 131. Instrument amplifier; 14. Analog multiplier; 15. Sampling resistor; 16. DC blocking capacitor; 17. Follower; 18. Battery to be tested. DETAILED DESCRIPTION

[0050] 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 only 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.

[0051] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, the use of "based on" or "according to" means openness and inclusiveness, because the process, steps, calculations or other actions "based on" or "according to" one or more of the conditions or values ​​may be based on additional conditions or values ​​beyond the described values ​​in practice.

[0052] The embodiment of the present invention provides a battery internal resistance measurement system and method based on sinusoidal wave discharge, which can filter out electromagnetic induction voltage and accurately measure and control the real battery AC part internal resistance.

[0053] like Figure 1 As shown, in the first aspect, an embodiment of the present invention provides a battery internal resistance measurement system based on sinusoidal wave discharge, the system comprising: a microcontroller 11, a constant current discharge circuit 12, an AC coupling amplifier circuit 13, an analog multiplier 14, a sampling resistor 15 and a DC blocking capacitor 16.

[0054] The microcontroller 11 is used to output an original sinusoidal signal with a frequency of 1 kHz.

[0055] The constant current discharge circuit 12, the sampling resistor 15 and the battery to be tested 18 are connected in series to form a battery discharge loop. The constant current discharge circuit 12 uses the original sinusoidal signal as a reference waveform to make the discharge waveform of the battery to be tested 18 a sinusoidal wave.

[0056] The two electrodes of the battery 18 to be tested are respectively connected to the AC coupling amplifier circuit 13 through a DC blocking capacitor 16 , so that the internal resistance voltage signal of the battery 18 to be tested is coupled to the AC coupling amplifier circuit 13 .

[0057] The AC coupling amplifier circuit 13 is used to amplify the internal resistance voltage signal by a preset multiple to obtain an amplified signal.

[0058] The analog multiplier 14 is used to perform a multiplication operation on the original sinusoidal signal and the amplified signal, and transmit the obtained composite signal to the microcontroller 11 .

[0059] The composite signal includes a DC component and an AC component with a frequency twice that of the original sinusoidal signal, and the DC component has the same frequency as the AC component and a phase difference of zero.

[0060] Both ends of the sampling resistor 15 are connected to the microcontroller 11 in a differential input manner.

[0061] The microcontroller 11 is also used to collect the current signal passing through the sampling resistor 15 and obtain the current amplitude of the current signal at 1 kHz.

[0062] The microcontroller 11 is also used to collect the voltage amplitude of the DC component of the integrated signal, and determine the internal resistance of the battery 18 to be tested according to the voltage amplitude of the DC component, a preset multiple and the current amplitude at 1 kHz.

[0063] In this embodiment, the microcontroller 11 includes a digital-to-analog conversion module and an analog-to-digital conversion module; the digital-to-analog conversion module Figure 1 DAC is used to represent the analog-to-digital conversion module, which includes a current acquisition part and a voltage acquisition part.

[0064] During the test, the digital-to-analog conversion module of the microcontroller 11 outputs an original sinusoidal signal with a frequency of 1 kHz.

[0065] The constant current discharge circuit 12 uses the original sinusoidal signal output by the digital-to-analog conversion module of the microcontroller 11 as a reference waveform, and makes the discharge waveform of the battery under test 18 a sinusoidal wave. Since the battery under test 18 has an internal resistance, the discharge waveform of the battery under test 18 will produce a slight voltage change compared with the reference waveform.

[0066] The two electrodes of the battery 18 to be tested are connected to the AC coupling amplifier circuit 13 through the DC blocking capacitors C1 and C2, so that the internal resistance voltage signal of the battery 18 to be tested is coupled to the AC coupling amplifier circuit 13 through the DC blocking capacitors C1 and C2, and the internal resistance voltage signal is amplified by G times to obtain an amplified signal.

[0067] The sampling resistor 15 is represented by Rs in the figure. During the discharge process of the battery 18 to be tested, the current flowing through the sampling resistor 15 is changing, and the discharge wiring method forms a loop with the battery 18 to be tested, thereby generating an electromagnetic induced voltage. By studying the discharge waveform of the battery 18 to be tested, it can be seen that the electromagnetic induced voltage has the same frequency as the original sinusoidal signal, and the phase difference is 90 degrees.

[0068] When the original sinusoidal signal is V1 and the amplified signal is V2, assuming , .

[0069] The original sinusoidal signal and the amplified signal are multiplied by the analog multiplier 14 to obtain a composite signal: .

[0070] The resulting composite signal is a sinusoidal signal with a DC offset that is twice the size of the original signal. That is, the composite signal includes a DC component and an AC component that is twice the size of the original sinusoidal signal. The DC component and the AC component have the same frequency and a phase difference of zero.

[0071] The analog-to-digital conversion module of the microcontroller 11 obtains the current signal passing through the sampling resistor 15 in a differential sampling manner, and obtains the current amplitude of the current signal at 1 kHz; at the same time, the voltage amplitude of the DC component in the integrated signal is collected by the analog-to-digital conversion module of the microcontroller 11. Finally, the microcontroller 11 determines the internal resistance of the battery 18 to be tested according to the voltage amplitude of the DC component, the preset multiple, and the current amplitude at 1 kHz.

[0072] In this embodiment, the battery internal resistance measurement system based on sinusoidal wave discharge further includes a battery or an external power supply circuit for providing working power to the microcontroller 11 , the AC coupling amplifier circuit 13 and the constant current discharge circuit 12 .

[0073] The present invention realizes synchronous detection operation by cooperating with the analog multiplier 14 and the microcontroller 11, thereby eliminating the influence of the electromagnetic induction voltage on the battery internal resistance test result, thereby accurately measuring and controlling the real battery AC part internal resistance.

[0074] Furthermore, the current signal passing through the sampling resistor 15 is collected, and the current amplitude of the current signal at 1 kHz is obtained, which specifically includes:

[0075] In each sampling period, 2 n Sampling points are provided, and for each sampling point, the voltage variation at both ends of the sampling resistor 15 is collected simultaneously.

[0076] The amplitude of the current signal corresponding to each sampling point is the ratio of the voltage change at the sampling point to the resistance value of the sampling resistor 15, and n≥8.

[0077] 2 n After Fourier transform of each sampling point, the voltage amplitude corresponding to 1KHZ is obtained.

[0078] According to the ratio of the voltage amplitude corresponding to 1 kHz to the resistance value of the sampling resistor 15 , the current amplitude at 1 kHz is obtained.

[0079] In one embodiment of the present invention, the voltage amplitude of the DC component of the integrated signal is collected, specifically:

[0080] The AC component in the integrated signal is filtered out by a low-pass filter arranged in the microcontroller 11 to obtain a DC component, and the voltage amplitude of the DC component is acquired.

[0081] In another embodiment of the present invention, collecting the voltage amplitude of the DC component of the integrated signal specifically includes:

[0082] In each sampling period, 2 n sampling points, and the voltage amplitude of the integrated signal is collected at each sampling point.

[0083] 2 n After Fourier transform of the sampling points, the zero-frequency amplitude is obtained.

[0084] Among them, the zero-frequency amplitude is the voltage amplitude of the DC component.

[0085] Furthermore, the voltage amplitude of the DC component, the preset multiple, and the current amplitude at 1 kHz determine the internal resistance of the battery 18 to be tested, specifically:

[0086] The target voltage amplitude is determined according to the ratio of the voltage amplitude of the DC component to a preset multiple.

[0087] The internal resistance of the battery 18 to be tested is determined based on the ratio of the target voltage amplitude to the current amplitude at 1 kHz.

[0088] That is, the internal resistance of the battery 18 to be tested is determined according to the following formula:

[0089] ;

[0090] in, represents the internal resistance of the battery 18 to be tested, Indicates the current amplitude at 1KHZ, Indicates the voltage amplitude corresponding to 1KHZ, represents the resistance value of the sampling resistor 15, represents the voltage amplitude of the DC component, Indicates the preset multiple.

[0091] Furthermore, in order to improve the load capacity of the original sinusoidal signal, the battery internal resistance measurement system based on sinusoidal wave discharge of the present invention further includes a follower 17 .

[0092] The input end of the follower 17 is connected to the microcontroller 11 , and the output end of the follower 17 is connected to the input end of the constant current discharge circuit 12 and the input end of the analog multiplier 14 .

[0093] like Figure 1, Figure 2 As shown, the constant current discharge circuit 12 includes an operational amplifier 121 and a MOS tube 122 .

[0094] The in-phase input terminal of the operational amplifier 121 is connected to the microcontroller 11 for receiving the original sinusoidal signal, the inverting input terminal of the operational amplifier 121 is connected to the source of the MOS tube 122, and the output terminal of the operational amplifier 121 is connected to the gate of the MOS tube 122;

[0095] The drain of the MOS tube 122 is connected to the positive electrode of the battery 18 to be tested, and the source of the MOS tube 122 is connected to the negative electrode of the battery 18 to be tested through the sampling resistor 15 .

[0096] Specifically, in an embodiment of the present invention, the original sinusoidal signal DAC_OUT output by the microcontroller 11 is connected to the in-phase input terminal of the operational amplifier 121 through the first resistor and the second resistor in sequence, one end of the first resistor connected to the second resistor is grounded through a capacitor, and one end of the second resistor connected to the in-phase input terminal of the operational amplifier 121 is grounded through a third resistor.

[0097] The positive power supply of the operational amplifier 121 is connected to the 3.3V operational amplifier operating voltage, which is represented by V3P3 in the figure. The access point of the 3.3V operational amplifier operating voltage is grounded through two parallel capacitors; the negative power supply of the operational amplifier 121 is grounded.

[0098] The MOS tube 122 is represented by Q1 in the figure. The inverting input terminal of the operational amplifier 121 is connected to the source of the MOS tube 122 and one end of the sampling resistor 15. The output terminal of the operational amplifier 121 is connected to the gate of the MOS tube 122 through a fourth resistor. A capacitor is connected between the source and gate of the MOS tube 122.

[0099] The drain of the MOS tube 122 is connected to the positive electrode of the battery 18 to be tested, which is represented by VBAT+ in the figure, and the other end of the sampling resistor 15 is connected to the negative electrode of the battery 18 to be tested, which is represented by VBAT- in the figure.

[0100] During the discharge process of the battery 18 to be tested, when the voltage of the sampling resistor 15 changes, the voltage is fed back to the inverting input terminal of the operational amplifier 121, and the difference with the non-inverting input terminal of the operational amplifier 121 is amplified. The output of the operational amplifier 121 controls the gate voltage of the MOS tube 122, changes the internal resistance of the MOS tube 122, and makes the discharge waveform of the battery 18 to be tested present a sine wave.

[0101] Specifically, the current acquisition part of the analog-to-digital conversion module of the microcontroller 11 first acquires the voltage change at both ends of the sampling resistor 15, and then determines the current passing through the sampling resistor 15 by the ratio of the voltage change to the resistance value of the sampling resistor 15. In this embodiment, the current acquisition part acquires the voltage change of multiple sampling points, calculates the voltage amplitude by Fourier transform, and finally determines the current amplitude by the ratio of the voltage amplitude to the resistance value of the sampling resistor 15.

[0102] like Figure 3 As shown, the AC coupling amplifier circuit 13 includes an instrumentation amplifier 131;

[0103] The positive electrode of the signal input terminal of the instrument amplifier 131 is connected to the negative electrode of the battery to be tested 18 through a DC blocking capacitor 16, the negative electrode of the signal input terminal of the instrument amplifier 131 is connected to the positive electrode of the battery to be tested 18 through a DC blocking capacitor 16, and the output terminal of the instrument amplifier 131 is connected to the input terminal of the analog multiplier 14.

[0104] In this embodiment, the positive electrode of the battery 18 to be tested is represented by VBAT+, the negative electrode of the battery 18 to be tested is represented by VBAT-, the 1.5V reference voltage is represented by VDD15, and the 3.3V operating voltage of the instrumentation amplifier 131 is represented by V3P3.

[0105] The positive electrode of the battery 18 to be tested is connected to the -IN pin of the instrument amplifier 131 through the DC blocking capacitor C2 and the fifth resistor in turn, and the negative electrode of the battery 18 to be tested is connected to the +IN pin of the instrument amplifier 131 through the DC blocking capacitor C1 and the sixth resistor in turn; the end of the DC blocking capacitor C2 connected to the fifth resistor is connected to the 1.5V reference voltage through the resistor, and the end of the DC blocking capacitor C1 connected to the sixth resistor is connected to the 1.5V reference voltage through the resistor; the end of the fifth resistor connected to the -IN pin is grounded through a capacitor, and the end of the sixth resistor connected to the +IN pin is grounded through a capacitor, and the -IN pin and the +IN pin are connected in series through a capacitor. A resistor is connected in series between the two RG pins of the instrument amplifier 131. The +VS pin of the instrument amplifier 131 is connected to a 3.3V operating voltage, and the +VS pin of the instrument amplifier 131 is also grounded through two parallel capacitors; the REF pin of the instrument amplifier 131 is a 1.5V reference voltage, and is grounded through two parallel capacitors, and the -VS pin of the instrument amplifier 131 is grounded. The VOUT pin of the instrument amplifier 131 outputs the amplified signal Vout after passing through a resistor.

[0106] Specifically, the voltage fluctuation of the battery 18 to be tested is AC-coupled to the output terminal VOUT of the instrument amplifier 131 through the DC blocking capacitor C1 and the DC blocking capacitor C2, and the amplification factor of the signal is adjusted according to the voltage fluctuation amplitude.

[0107] like Figure 4As shown, the amplified signal output by the instrumentation amplifier 131 after amplification by a preset multiple and the original sinusoidal signal output by the follower 17 after the output signal load capacity is increased are multiplied in the analog multiplier 14, and a composite signal having frequency components in the form of sum frequency and difference frequency is obtained. In other words, the analog multiplier 14 outputs a DC component and an AC component with a frequency twice that of the original sinusoidal signal, and the DC component has the same frequency as the AC component and the phase difference is 0.

[0108] Specifically, during the discharge process of the battery 18 to be tested, an induced voltage signal is generated. When the constant current discharge circuit 12, the sampling resistor 15 and the battery 18 to be tested are connected in series to form a battery discharge circuit with the loop current being the largest, the magnetic field changes the most, that is, the induced voltage is the largest. At this time, there is a 90-degree phase difference between the induced voltage and the original sinusoidal signal.

[0109] In the analog multiplier 14, according to the formula:

[0110] ;

[0111] in, B represents the amplitude of the original sinusoidal signal, C Represents the amplitude of the electromagnetic induced voltage, f m The signal frequency representing the original sinusoidal signal.

[0112] According to the output result of the analog multiplier 14, it can be known that the integrated signal output by the analog multiplier 14 is an AC signal that is twice as large as the original sine wave signal.

[0113] In the microcontroller unit, the AC component is filtered out by a low-pass filter to obtain the voltage amplitude of the DC component; or the voltage amplitude of the DC component is obtained by taking the amplitude of the zero-frequency signal through Fourier transform at multiple sampling points.

[0114] like Figure 5 As shown, an embodiment of the present invention further provides a method for measuring the internal resistance of a battery based on sinusoidal discharge. The method is applied to a microcontroller of the internal resistance of a battery based on sinusoidal discharge. The method includes:

[0115] Step 101: Output an original sinusoidal signal with a frequency of 1 kHz.

[0116] Step 102: In the process of the constant current discharge circuit using the original sinusoidal signal as a reference waveform to control the battery under test to output a sinusoidal discharge waveform, a current signal passing through the sampling resistor is collected, and the current amplitude of the current signal at 1 kHz is obtained.

[0117] Step 103: collecting the voltage amplitude of the DC component of the integrated signal output by the analog multiplier.

[0118] The integrated signal is obtained by amplifying the internal resistance voltage signal by a preset multiple through an AC coupling amplifier circuit, and then multiplying the integrated signal with the original sinusoidal signal in an analog multiplier.

[0119] Step 104: Determine the internal resistance of the battery to be tested according to the voltage amplitude of the DC component, the preset multiple, and the current amplitude at 1 kHz.

[0120] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the method described above can refer to the corresponding process in the aforementioned system embodiment, and will not be repeated here.

[0121] In a third aspect, an embodiment of the present invention further provides an electronic device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor to implement the measurement method of the battery internal resistance measurement system based on sinusoidal wave discharge in the embodiment of the present invention.

[0122] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the measurement method of a battery internal resistance measurement system based on sinusoidal wave discharge in an embodiment of the present invention.

[0123] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that can be accessed by the computer or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk Solid State Disk (SSD)), etc.

[0124] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A battery internal resistance measurement system based on sinusoidal discharge, characterized in that: It includes a microcontroller, a constant current discharge circuit, an AC coupling amplifier circuit, an analog multiplier, a sampling resistor and a DC blocking capacitor; The microcontroller is used to output an original sinusoidal signal with a frequency of 1KHZ; The constant current discharge circuit, the sampling resistor and the battery to be tested are connected in series to form a battery discharge loop; the constant current discharge circuit uses the original sinusoidal signal as a reference waveform to make the discharge waveform of the battery to be tested a sinusoidal wave; The two electrodes of the battery to be tested are respectively connected to the AC coupling amplifier circuit through one of the DC blocking capacitors, so that the internal resistance voltage signal of the battery to be tested is coupled to the AC coupling amplifier circuit; The AC coupling amplifier circuit is used to amplify the internal resistance voltage signal by a preset multiple to obtain an amplified signal; The analog multiplier is used to perform a multiplication operation on the original sinusoidal signal and the amplified signal, and transmit the obtained composite signal to the microcontroller; the composite signal includes a DC component and an AC component with a frequency twice that of the original sinusoidal signal, the DC component has the same frequency as the AC component and the phase difference is zero; The two ends of the sampling resistor are connected to the microcontroller in a differential input manner; The microcontroller is also used to collect the current signal passing through the sampling resistor and obtain the current amplitude of the current signal at 1KHZ; The microcontroller is also used to collect the voltage amplitude of the DC component of the integrated signal, and determine the internal resistance of the battery to be tested according to the voltage amplitude of the DC component, the preset multiple and the current amplitude at 1KHZ; the internal resistance of the battery to be tested is determined according to the following formula: ； in, Indicates the internal resistance of the battery to be tested. Indicates the current amplitude at 1KHZ, Indicates the voltage amplitude corresponding to 1KHZ, Indicates the resistance of the sampling resistor. represents the voltage amplitude of the DC component, Indicates the preset multiple; Collecting the current signal passing through the sampling resistor and obtaining the current amplitude of the current signal at 1 kHz specifically includes: In each sampling period, 2 n sampling points, for each sampling point, simultaneously collecting the voltage change at both ends of the sampling resistor; the amplitude of the current signal corresponding to each sampling point is the ratio of the voltage change at the sampling point to the resistance value of the sampling resistor, and n≥8; Regarding the 2 n After Fourier transform of each sampling point, the voltage amplitude corresponding to 1KHZ is obtained; According to the ratio of the voltage amplitude corresponding to the 1KHZ to the resistance value of the sampling resistor, the current amplitude at 1KHZ is obtained; The voltage amplitude of the DC component of the integrated signal is collected, specifically: By means of a low-pass filter provided in the microcontroller, an AC component in the integrated signal is filtered out to obtain a DC component, and a voltage amplitude of the DC component is acquired; Collecting the voltage amplitude of the DC component of the integrated signal specifically includes: In each sampling period, 2 n sampling points, collecting the voltage amplitude of the integrated signal at each sampling point; Regarding the 2 n After Fourier transformation of the sampling points, the zero-frequency amplitude is obtained; the zero-frequency amplitude is the voltage amplitude of the DC component; The AC coupling amplifier circuit includes an instrument amplifier; The positive electrode of the signal input terminal of the instrument amplifier is connected to the negative electrode of the battery to be tested through the DC blocking capacitor, the negative electrode of the signal input terminal of the instrument amplifier is connected to the positive electrode of the battery to be tested through the DC blocking capacitor, and the output terminal of the instrument amplifier is connected to the input terminal of the analog multiplier.

2. The battery internal resistance measurement system based on sinusoidal wave discharge according to claim 1, characterized in that: The voltage amplitude of the DC component, the preset multiple and the current amplitude at 1 kHz are used to determine the internal resistance of the battery to be tested, specifically: Determining a target voltage amplitude according to a ratio of the voltage amplitude of the DC component to the preset multiple; The internal resistance of the battery to be tested is determined according to the ratio of the target voltage amplitude to the current amplitude at 1 kHz.

3. The battery internal resistance measurement system based on sinusoidal wave discharge according to claim 1, characterized in that: Also includes followers; The input end of the follower is connected to the microcontroller, and the output end of the follower is connected to the input end of the constant current discharge circuit and the input end of the analog multiplier; the follower is used to improve the load capacity of the original sinusoidal signal.

4. The battery internal resistance measurement system based on sinusoidal wave discharge according to claim 1, characterized in that: The constant current discharge circuit includes an operational amplifier and a MOS tube; The in-phase input terminal of the operational amplifier is connected to the microcontroller for receiving the original sinusoidal signal, the inverting input terminal of the operational amplifier is connected to the source of the MOS tube, and the output terminal of the operational amplifier is connected to the gate of the MOS tube; The drain of the MOS tube is connected to the positive electrode of the battery to be tested, and the source of the MOS tube is connected to the negative electrode of the battery to be tested through the sampling resistor.

5. A method for measuring the internal resistance of a battery based on sinusoidal discharge, characterized in that: A microcontroller applied to a battery internal resistance measurement system based on sinusoidal wave discharge according to any one of claims 1 to 4, wherein the measurement method comprises: Output frequency is 1KHZ original sinusoidal signal; In the process of the constant current discharge circuit using the original sinusoidal signal as a reference waveform to control the battery to be tested to output a sinusoidal discharge waveform, collecting a current signal passing through the sampling resistor, and obtaining a current amplitude of the current signal at 1 kHz; The voltage amplitude of the DC component of the integrated signal output by the analog multiplier is collected; the integrated signal is obtained by multiplying the internal resistance voltage signal by a preset multiple through an AC coupling amplifier circuit, and the integrated signal is obtained by multiplying the original sinusoidal signal in the analog multiplier; the AC coupling amplifier circuit includes an instrument amplifier; the positive electrode of the signal input terminal of the instrument amplifier is connected to the negative electrode of the battery to be tested through a DC blocking capacitor, the negative electrode of the signal input terminal of the instrument amplifier is connected to the positive electrode of the battery to be tested through a DC blocking capacitor, and the output terminal of the instrument amplifier is connected to the input terminal of the analog multiplier; The internal resistance of the battery to be tested is determined according to the voltage amplitude of the DC component, the preset multiple, and the current amplitude at 1 kHz; the internal resistance of the battery to be tested is determined according to the following formula: ； in, Indicates the internal resistance of the battery to be tested. Indicates the current amplitude at 1KHZ, Indicates the voltage amplitude corresponding to 1KHZ, Indicates the resistance of the sampling resistor. represents the voltage amplitude of the DC component, Indicates the preset multiple; Collecting the current signal passing through the sampling resistor and obtaining the current amplitude of the current signal at 1 kHz specifically includes: In each sampling period, 2 n sampling points, for each sampling point, simultaneously collecting the voltage change at both ends of the sampling resistor; the amplitude of the current signal corresponding to each sampling point is the ratio of the voltage change at the sampling point to the resistance value of the sampling resistor, and n≥8; Regarding the 2 n After Fourier transform of each sampling point, the voltage amplitude corresponding to 1KHZ is obtained; According to the ratio of the voltage amplitude corresponding to the 1KHZ to the resistance value of the sampling resistor, the current amplitude at 1KHZ is obtained; The voltage amplitude of the DC component of the integrated signal is collected, specifically: By means of a low-pass filter provided in the microcontroller, an AC component in the integrated signal is filtered out to obtain a DC component, and a voltage amplitude of the DC component is acquired; Collecting the voltage amplitude of the DC component of the integrated signal specifically includes: In each sampling period, 2 n sampling points, collecting the voltage amplitude of the integrated signal at each sampling point; Regarding the 2 n After Fourier transformation of the sampling points, the zero-frequency amplitude is obtained; the zero-frequency amplitude is the voltage amplitude of the DC component.

6. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the measurement method of the battery internal resistance measurement system based on sinusoidal wave discharge as claimed in claim 5.

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