Implementation method of frequency sweep type storage battery internal resistance test system

Abstract

The invention discloses an implementation method of a frequency sweep type storage battery internal resistance test system. The method comprises a digital synthesis technology generation method based on a non-injection type test signal source. A generation method for extracting a synchronization signal based on a non-phase-locked loop mode; the invention discloses a multiplier implementation method based on a digital switching technology and an analog switch. The invention discloses an implementation method for realizing high-precision storage battery internal resistance testing based on a non-high-precision device. The invention discloses a method for realizing internal resistance test data and charts of a storage battery based on strong processing capacity of a smart phone. According to the frequency sweep type storage battery internal resistance test system, high-precision storage battery internal resistance test data can be obtained with low implementation cost, and visual test comparison data can be obtained for the storage battery internal resistance test for a user; and the storage battery can be conveniently and effectively maintained, and different storage battery internal resistance test conclusions can be discriminated to form a comparative analysis conclusion.

Description

Technical Field

[0001] The invention relates to the technical field of battery internal resistance testing, and in particular to a method for realizing a frequency sweeping type battery internal resistance testing system. Background Art

[0002] As a backup energy source, batteries are widely used in various information transmission and automation control occasions. In the digital economy era, the entire society relies heavily on uninterrupted power to provide reliable support for the digital economy. For well-known reasons, all data transmission and storage cannot be separated from the support of electricity, and the importance of batteries as a backup power source is self-evident.

[0003] As an electrochemical energy source, the physical and chemical factors of the battery itself determine that it may age, have defects and malfunctions.

[0004] Battery internal resistance is a key technical indicator of battery performance. Therefore, currently backup power batteries are generally equipped with battery online monitoring systems. Many battery online monitoring systems often only detect battery voltage and temperature data, which cannot fully reflect the performance of the battery; and battery online monitoring systems with battery internal resistance detection function are very expensive due to technical and material reasons. In addition, the test accuracy of battery internal resistance has always been a problem that troubles many users. Using different test signals and different test methods will result in very different test conclusions.

[0005] The present invention is proposed based on the above-mentioned problems. Summary of the invention

[0006] The present invention is based on the following content and is described step by step:

[0007] A method for implementing a sweep frequency type battery internal resistance test system, characterized in that it comprises the steps of:

[0008] S1, a method for generating a digital synthesis technology based on a non-injection test signal source;

[0009] S2, a method for extracting a synchronization signal based on a non-phase-locked loop method;

[0010] S3, a multiplier implementation method based on digital switching technology and analog switches;

[0011] S4, a method for realizing high-precision battery internal resistance testing based on the use of non-high-precision devices;

[0012] S5, a method for realizing battery internal resistance test data and charts based on the powerful processing capability of smart phones.

[0013] One of the points to be emphasized is that: the implementation method of the sweep frequency type battery internal resistance test system is characterized in that the constant current source signal for the battery internal resistance test is not injected externally, but a constant current discharge is realized in the battery in a sinusoidal manner required by the test signal to obtain the test signal;

[0014] The second point to be emphasized is that: the implementation method of the frequency sweeping type battery internal resistance test system is characterized in that the synchronization signal is extracted by a non-phase-locked loop method, and an MCU output synchronization signal generated synchronously with the test signal is used.

[0015] The third point to be emphasized is that: the method for realizing the sweep-frequency battery internal resistance test system is characterized in that: instead of using a complex multiplier IC, a digital switching technology and an analog switch multiplier are used to realize the extraction of battery internal resistance data.

[0016] The fourth point to be emphasized is: the implementation method of the swept-frequency battery internal resistance test system is characterized in that: no high-precision devices are used to ensure the test accuracy of the battery internal resistance, but non-high-precision devices are used to achieve high-precision battery internal resistance testing.

[0017] The fifth point to be emphasized is: the implementation method of the swept-frequency battery internal resistance test system is characterized in that: the battery internal resistance test system is not specially equipped with a powerful display and operation data processor, but the powerful processing capability of a smart phone is used to realize the display, operation, data and chart processing of the battery internal resistance test.

[0018] Furthermore, the implementation method of the frequency sweeping type battery internal resistance test system is characterized by being applicable to the internal resistance test of various secondary batteries.

[0019] The present invention is based on the mathematical model and test principle of the internal resistance of the battery. A constant AC current signal Is is added between the positive and negative electrodes of the battery, and the voltage response signal V0 at both ends of the battery is measured. The phase difference θ between the two is used to determine the internal resistance R of the battery by the impedance formula Z=V / Is and R=Zcosθ.

[0020] Here is a brief introduction to this principle:

[0021] Assume the sinusoidal signal is: 1(ωt) =A cosωt, the frequency sweeping method proposed in the present invention actually changes the frequency of the sinusoidal signal.

[0022] (1) The response voltage signal at both ends of the battery is: u 2(ωt) =B cos(ωt+θ)

[0023] (2)θ is the phase difference between the AC current injected into the battery and the voltage signal at the other two ends. After passing through the analog multiplier, we have:

[0024] u(ωt)=ku1(ωt)·u2(ωt)=kAB cosωt·cos(ωt+θ)=0.5kAB[cosθ+cos(2ωt+θ)]

[0025] K is the amplification factor of the analog multiplier. Low-pass filtering is performed to filter out the AC component and obtain: u = 0.5KABcosθ

[0026] (4) According to the principle of measuring internal resistance by AC method, we can get: R = Bcosθ / I; where I is the maximum value of the AC constant current source signal. Comparing (3) and (4), we can get R = 2u / KAI. In the above formula, K, A, and I are all known quantities, and u is the sampled value sent to MCU for processing after A / D sampling. After simple calculation, the internal resistance of the battery can be obtained.

[0027] From the principle of battery internal resistance test, the technical difficulty of frequency sweep internal resistance test system lies in: the realization of constant current source and multiplier. It is conceivable how costly and difficult it is to realize a 1Hz~1MHz constant current source and a 1Hz~1MHz phase-locked loop device.

[0028] The present invention adopts a digital synthesis technology generation method of a non-injection test signal source, adopts an MCU to synthesize a sine wave of a response frequency, and a high-speed MCU to easily realize the required sine wave signals of different frequencies.

[0029] Furthermore, according to the battery internal resistance test principle, if the signal synchronized with the input signal required by the multiplier is obtained by using a phase-locked loop IC, there are not only technical difficulties in wide frequency, but also great problems in cost and stability. The synchronization signal of the multiplier proposed in the present invention generates a sine wave by the MCU while also generating a synchronization signal of the multiplier, without the need for an external phase-locked loop device, and ensures the scientificity and stability of the phase-locked signal.

[0030] Furthermore, according to the battery internal resistance test principle, the multipliers of the traditional technology are all implemented by using a dedicated IC. The present invention uses the synchronization signal output by the MCU to drive the electronic switch to implement the multiplier described in the battery internal resistance test principle, which greatly reduces the cost of the internal resistance test system.

[0031] Furthermore, according to the battery internal resistance test principle, the signal output by the multiplier needs to be further filtered and amplified, and the accuracy of the electronic device directly affects the accuracy of the internal resistance test. The present invention uses ordinary electronic devices and adopts the MCU calibration method to directly eliminate the error problem caused by the consistency of the electronic devices, thereby ensuring the accuracy of the battery internal resistance test.

[0032] Furthermore, the sweep-frequency battery internal resistance test system needs to set up, operate, display and process data in a wide frequency range. If a dedicated display and operation module is configured for the sweep-frequency battery internal resistance test system, it will bring huge costs and bring many inconveniences to packaging, transportation, carrying and on-site use. The sweep-frequency battery internal resistance test module has built-in Bluetooth and WIFI modules. Combined with a smartphone, downloading a small program can solve these complex problems; in addition, the internal program of the sweep-frequency internal tester can be downloaded and updated through a smartphone as needed.

[0033] Furthermore, the method of the present invention is applicable to the internal resistance test of all secondary batteries and has a wide range of application scenarios.

[0034] The beneficial effect of the present invention is that, compared with the prior art, the present invention can test the internal resistance of the battery at a lower cost, in a simpler implementation method, with higher accuracy and more convenient operation, which can generate huge social and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 System composition architecture diagram;

[0036] Figure 2 Non-injection test signal generation process;

[0037] Figure 3 Internal resistance test multiplier synchronization signal generation process.

[0038] Figure 4 Non-injection test signal source generation circuit

[0039] Figure 5 Internal resistance test multiplier circuit without phase-locked loop

[0040] Figure 6 Non-high-precision device multi-stage amplifier circuit

[0041] Figure 7 Connection diagram of swept frequency internal resistance test system DETAILED DESCRIPTION

[0042] 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.

[0043] See also Figure 1The system composition diagram describes the hardware composition and the core composition framework of the sweep frequency internal resistance test device. In the diagram, the relationship between the signal source generation, external signal input, multiplier, amplifier, MCU and external communication module of the battery internal resistance test is described;

[0044] Figure 2 Non-injection test signal generation process combined Figure 4 , can fully describe the generation of this sinusoidal wave signal and the travel of the sinusoidal wave test signal formed at the positive and negative poles of the battery.

[0045] Let's take the example of obtaining a 1KHz sine wave test signal:

[0046] The built-in sine wave of the MCU forms a dot matrix. The peak of the sine wave has the highest data density, and the trough of the sine wave has the lowest data density, or even 0. The data of the dot matrix can be stored as 180°, half of a cycle of 360°. In actual use, our dot matrix stores a group of dot matrix data every 5°; the change of data amplitude is directly based on u 1(ωt) =A cosωt calculation.

[0047] After the dot matrix data is converted by D / A, it is output from the D / A conversion I / O port of the MCU. Figure 4 PWM0 in the circuit, this signal passes through the operational amplifier and drives Figure 4 The NMOS device in the battery is turned on, forming an AC discharge current of 1KHz at the positive and negative terminals of the battery. Figure 4 RL in the figure is the load resistor. For the 2V battery internal resistance test circuit, this resistor uses a 0.1Ω power resistor. It is also the feedback loop of the constant current source. This feedback signal ensures that the circuit is in a constant current discharge state. For the 12V battery internal resistance test, this resistor uses a 4Ω power resistor. For lead-acid batteries with a capacity of 1000AH or less, the above load resistor has met the AC current amplitude requirements required for the internal resistance test. For lead-acid batteries over 1000AH, since the battery internal resistance is small, a larger AC current is required. By reducing the load resistance mode, a larger AC current constant current discharge can be achieved, thereby realizing the internal resistance test of large-capacity batteries.

[0048] Figure 3 It is the internal resistance test multiplier synchronization signal generation process, combined with Figure 5 The non-phase-locked loop internal resistance test multiplier circuit is the core structure of the present invention.

[0049] According to the test principle of battery internal resistance, the following formula is relied on:

[0050] u(ωt)=ku1(ωt)·u2(ωt)=kAB cosωt·cos(ωt+θ)=0.5kAB[cosθ+cos(2ωt+θ)]

[0051] If the two signals passing through the multiplier have different frequencies, it is basically impossible to obtain the internal resistance of the battery in a simple way. Therefore, the acquisition of this synchronous signal is the core link to realize this test. In actual use, Figure 2 The signal generation process and Figure 3 The generation process is embedded in the MCU program. Figure 2 The signal generation process is implemented in the next Figure 3 The synchronization signal generation process ensures that the error of the synchronization signal does not exceed one MCU machine cycle. The MCU we use only takes 10nS for each machine cycle. For low-frequency sine wave signals, such as a 1KHz sine wave, one cycle is 1mS, and the synchronization error is one in 100,000, which fully meets the needs of signal synchronization.

[0052] Figure 5 The multiplier circuit, the synchronization signal is CTL in the figure, this signal controls the electronic switch to realize the multiplication operation of the reflected signal of the battery internal resistance test and the synchronization signal.

[0053] exist Figure 3 The synchronization signal generation process only needs to output TTL level, which could have been implemented in a simpler way. However, in order to ensure the accuracy of the synchronization signal, in actual implementation, the generation of TTL signal is the same as that of sine wave signal, and the same program flow is executed to fully realize the synchronous output of the two signals.

[0054] Figure 6 It is a multi-stage amplifier circuit composed of non-high-precision devices. This circuit is used to amplify the weak signal of the battery internal resistance test multiplier. When the internal resistance of the battery is relatively small, this signal needs to be discharged at multiple stages to meet the sampling range of the A / D sampling circuit inside the MCU. For tiny signals, if the circuit amplification factor needs to be consistent, high-precision resistors, capacitors and operational amplifiers are required, which will inevitably lead to an increase in manufacturing costs.

[0055] In actual use, we use standard internal resistance to calibrate this multi-stage amplifier. The MCU tests the battery with standard internal resistance, records the A / D value of the standard value, and then calculates the A / D value and the calibration value in the actual test to obtain the battery internal resistance with high accuracy.

[0056] Figure 6In the test, a three-stage amplifier is used. The MCU samples the output of the first-stage amplifier. When the full-scale requirement is not met, the output of the second-stage amplifier or the third-stage amplifier is sampled to ensure the accuracy of the internal resistance test.

[0057] The introduction of the external smart phone-related sweeping battery internal resistance device is actually a relatively simple and clear technical application. Relying on the powerful data processing capabilities of smart phones, a very good user experience can be obtained.

[0058] What's more convenient is that the sweeping frequency battery internal resistance tester can be upgraded through data interaction on a smartphone no matter where it is, which can provide users with better services conveniently and flexibly.

[0059] Those skilled in the art should be aware that, although the various methods of the present application are described based on the same concept and thus present commonality to each other, unless otherwise specified, these methods can be independently executed. Similarly, for each embodiment disclosed in the present application, they are all proposed based on the same inventive concept, therefore, concepts with the same expression, and concepts that are appropriately changed for convenience despite different expressions, should be understood as equivalent.

[0060] Unless the mutually exclusive relationship between the embodiments to be disclosed in this application is explicitly stated, the relevant technical features involved in each embodiment can be cross-combined to flexibly construct a new embodiment, as long as such combination does not deviate from the creative spirit of this application and can meet the needs of the prior art or solve certain deficiencies in the prior art. Those skilled in the art should be aware of this flexibility.

[0061] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for implementing a sweep frequency battery internal resistance test system, characterized in that: Includes steps: S1, a method for generating a digital synthesis technology based on a non-injection test signal source; S2, a method for extracting a synchronization signal based on a non-phase-locked loop method; S3, a multiplier implementation method based on digital switching technology and analog switches; S4, a method for realizing high-precision battery internal resistance testing based on the use of non-high-precision devices; S5, a method for realizing battery internal resistance test data and charts based on the powerful processing capability of smart phones.

2. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: The constant current source signal for testing the internal resistance of the battery is not injected externally, but a constant current discharge is achieved inside the battery in a sinusoidal manner as required by the test signal to obtain the test signal.

3. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: The synchronization signal is extracted by a non-phase-locked loop method, and an MCU output synchronization signal generated synchronously with the test signal is used instead.

4. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: Instead of using a complex multiplier IC, a digital switching technology and an analog switch multiplier are used to extract the battery internal resistance data.

5. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: High-precision devices are not used to ensure the test accuracy of the battery internal resistance, but non-high-precision devices are used to achieve high-precision battery internal resistance testing.

6. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: The battery internal resistance test system is not specially equipped with a powerful display and operation data processor. Instead, the powerful processing capability of a smartphone is used to realize the display, operation, data and chart processing of the battery internal resistance test.

7. The method for implementing a sweep frequency battery internal resistance test system as claimed in claim 1, characterized in that: Suitable for internal resistance testing of various secondary batteries.

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