A lithium battery AC internal resistance detection system

Abstract

The present invention provides a lithium battery AC internal resistance detection system in the field of lithium battery detection equipment technology, including an MCU module, a DAC module, a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a voltage-to-current module, a phase-sensitive detection initial phase zeroing module, a sampling signal conversion module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module, an ADC module, a sampling signal self-calibration module and a sampling signal full-wave rectification module. The advantages of the present invention are: fast and stable acquisition of the AC internal resistance of lithium batteries at different frequencies.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery detection equipment, and in particular to a lithium battery AC internal resistance detection system. Background Art

[0002] With the rapid development of lithium battery technology, the energy density of lithium batteries is getting higher and higher. Under different usage environments, the voltage of lithium batteries has their own differences. The effective utilization rate of battery energy is an important indicator to measure battery performance. The AC internal resistance of lithium batteries directly determines the energy loss of lithium batteries themselves during energy release. The AC internal resistance can be used to determine the battery capacity and whether the lithium battery needs to be replaced, thereby reducing the maintenance cost of lithium batteries; and as lithium batteries age and poor manufacturing will lead to battery performance degradation and irreversible changes in battery chemical composition, the AC internal resistance of lithium batteries increases linearly with the decrease in capacity; so it is necessary to test the AC internal resistance of lithium batteries.

[0003] The detection of lithium battery AC internal resistance is traditionally carried out under a fixed 1khz excitation source. There is no way to quickly and stably obtain the lithium battery AC internal resistance at different frequencies, and it is also impossible to obtain the electrochemical impedance spectrum information of the lithium battery at different frequencies. The electrochemical impedance spectrum information can be used to obtain the ohmic impedance of the lithium battery, the impedance of lithium ions passing through the solid electrolyte, the electrode polarization impedance, the lithium ion diffusion impedance and other information.

[0004] Therefore, how to provide a lithium battery AC internal resistance detection system to quickly and stably obtain the AC internal resistance of the lithium battery at different frequencies has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a lithium battery AC internal resistance detection system to achieve rapid and stable acquisition of the AC internal resistance of the lithium battery at different frequencies.

[0006] The present invention is implemented as follows: a lithium battery AC internal resistance detection system, including an MCU module, a DAC module, a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a voltage-to-current module, a phase-sensitive detection initial phase zeroing module, a sampling signal conversion module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module, an ADC module, a sampling signal self-calibration module and a sampling signal full-wave rectification module;

[0007] The MCU module, DAC module, DAC signal conversion module, DAC signal bandpass filter module, DAC signal gain module, DAC signal high-pass filter module, voltage-to-current module, phase-sensitive detection initial phase zeroing module, sampling signal conversion module, sampling signal gain module, sampling signal bandpass filter module, sampling signal phase-sensitive detection module and ADC module are connected in sequence;

[0008] The MCU modules are respectively connected to a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a phase-sensitive detection initial phase zeroing module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module and an ADC module;

[0009] The DAC module is connected to the ADC module and the sampling signal self-calibration module respectively; the ADC module is connected to the sampling signal self-calibration module; one end of the sampling signal full-wave rectification module is connected to the ADC module, and the other end is connected to the sampling signal bandpass filtering module.

[0010] Further, the DAC signal conversion module includes a digital-to-analog converter U7, an operational amplifier U3A, an operational amplifier U5B, a resistor R3, a resistor R4, a resistor R8, a resistor R9, a resistor R14, a resistor R24 ​​and a capacitor C11;

[0011] Pin 1 of the digital-to-analog converter U7 is connected to capacitor C11 and pin 6 of op amp U5B, pin 2 is connected to pin 5 of op amp U5B and grounded, pins 3, 4, and 5 are all connected to the MCU module, pin 7 is connected to the DAC module, and pin 8 is connected to resistor R8; pin 7 of the op amp U5B is connected to resistor R8, resistor R9, resistor R14, and capacitor C11; one end of the resistor R3 is connected to the DAC module, and the other end is connected to resistor R4, resistor R9, and pin 2 of op amp U3A; pin 1 of the op amp U3A is connected to resistor R4, resistor R24, and a DAC signal bandpass filter module.

[0012] Further, the DAC signal bandpass filter module includes a multiplexed analog switch U1, a multiplexed analog switch U2, a multiplexed analog switch U4, a multiplexed analog switch U8, a resistor R1, a resistor R2, a resistor R5, a resistor R6, a resistor R7, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R25, a resistor R37, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C14, a capacitor C15, a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21, an operational amplifier U5A, and an operational amplifier U3B;

[0013] One end of the resistor R13 is connected to the DAC signal conversion module, and the other end is connected to the resistor R15, the resistor R16, the resistor R17, the resistor R18, the resistor R19, the resistor R20, the resistor R21, the resistor R22, the pin 8 of the multiplexed analog switch U8, and the pin 3 of the operational amplifier U5A;

[0014] Pins 9, 10, 11, 12, 7, 6, 5, and 4 of the multiplexed analog switch U1 are respectively connected to resistors R15, R16, R17, R18, R19, R20, R21, and R22, pin 8 is connected to pin 8 of the multiplexed analog switch U2 and pin 7 of the operational amplifier U3B, and pins 1, 2, 15, and 16 are connected to the MCU module;

[0015] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U2 are connected to capacitors C1, C2, C3, C4, C5, C6, C7, and C8, respectively, and pins 1, 2, 15, and 16 are connected to the MCU module;

[0016] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U4 are connected to resistors R5, R6, R7, R10, R11, R12, R23, and R25, respectively; pin 8 is connected to capacitors C1, C2, C3, C4, C5, C6, C7, C8, pin 6 of op amp U3B, and pin 2 of op amp U5A; and pins 1, 2, 15, and 16 are connected to the MCU module;

[0017] One ends of the capacitors C14, C15, C16, C17, C18, C19, C20 and C21 are connected to each other and grounded, and the other ends are connected to pins 9, 10, 11, 12, 7, 6, 5 and 4 of the multiplex analog switch U8 respectively; pins 1, 2, 15 and 16 of the multiplex analog switch U8 are connected to the MCU module;

[0018] Pin 5 of the operational amplifier U3B is connected to resistor R1 and resistor R2; one end of the resistor R37 is connected to the DAC signal gain module, and the other end is connected to resistor R2, resistor R5, resistor R6, resistor R7, resistor R10, resistor R11, resistor R12, resistor R23, resistor R25 and pin 1 of the operational amplifier U5A.

[0019] Further, the DAC signal gain module includes a multiplexed analog switch U11, an operational amplifier U10B, a resistor R38, a resistor R40, a resistor R41, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53 and a resistor R54;

[0020] One end of the resistor R41 is connected to the DAC signal high-pass filter module, and the other end is connected to the resistor R38, the resistor R47, the resistor R48, the resistor R49, the resistor R50 and the pin 7 of the operational amplifier U10B; the pin 5 of the operational amplifier U10B is connected to the pin 9 of the multiplexing analog switch U11 and the DAC signal band-pass filter module, and the pin 6 is connected to the resistor R40 and the pin 8 of the multiplexing analog switch U11;

[0021] Pins 4, 5, 6, 7, 13, 12, 11, and 10 of the multiplexed analog switch U11 are respectively connected to resistors R47, R48, R49, R50, R51, R52, R53, and R54, and pins 1, 2, and 16 are connected to the MCU module; one ends of the resistors R51, R52, R53, and R54 are interconnected and grounded.

[0022] Further, the DAC signal high-pass filter module includes a multiplexed analog switch U13, an operational amplifier U10A, an operational amplifier U12B, a resistor R33, a resistor R34, a resistor R42, a resistor R44, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31 and a capacitor C32;

[0023] Pin 1 of the operational amplifier U10A is connected to the resistor R33, the resistor R42 and the voltage-to-current module, pin 2 is connected to the resistor R33 and the resistor R34, and pin 3 is connected to the resistor R44 and the DAC signal gain module;

[0024] Pin 6 of the operational amplifier U12B is connected to the resistor R42 and the pin 8 of the multiplexing analog switch U13, and pin 7 is connected to the resistor R44, the capacitor C25, the capacitor C26, the capacitor C27, the capacitor C28, the capacitor C29, the capacitor C30, the capacitor C31 and the capacitor C32;

[0025] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U13 are respectively connected to capacitors C25, C26, C27, C28, C29, C30, C31, and C32, and pins 1, 2, 15, and 16 are connected to the MCU module.

[0026] Further, the voltage-to-current module includes an operational amplifier U9A, an operational amplifier U9B, a clamping diode D1, a clamping diode D3, a clamping diode D4, a diode D2, a diode D5, a sampling resistor R29, a resistor R27, a resistor R28, a resistor R30, a resistor R31, a resistor R32, a resistor R35, a resistor R36, a resistor R39, a resistor R43, a resistor R45, a resistor R213, a capacitor C22, a capacitor C23, a capacitor C24, a transistor Q1, a transistor Q2, a transistor Q3 and a transistor Q4;

[0027] One end of the resistor R39 is connected to the DAC signal high-pass filter module, and the other end is connected to pin 3 of the operational amplifier U9A; pin 2 of the operational amplifier U9A is connected to resistor R36, capacitor C22 and capacitor C23, and pin 1 is connected to resistor R32 and resistor R213; the resistor R32 is connected to capacitor C22; the resistor R36 is connected to capacitor C23, resistor R27 and pin 7 of the operational amplifier U9B;

[0028] The input end of the diode D2 is connected to the resistor R28 and the b-pole of the transistor Q2, and the output end is connected to the resistor R213 and the input end of the diode D5; the output end of the diode D5 is connected to the resistor R43 and the b-pole of the transistor Q4;

[0029] The c-pole of the transistor Q2 is connected to the resistor R28, and the e-pole is connected to the b-pole of the transistor Q1; the c-pole of the transistor Q4 is connected to the resistor R43, and the e-pole is connected to the b-pole of the transistor Q3; one end of the resistor R45 is connected to the capacitor C24, and the other end is connected to the clamping diode D4, the e-pole of the transistor Q1 and the e-pole of the transistor Q3; the capacitor C24 is connected to the phase-sensitive detection initial phase zeroing module;

[0030] Pin 5 of the operational amplifier U9B is connected to resistor R31, resistor R35 and clamping diode D3, and pin 6 is connected to resistor R27, resistor R30 and clamping diode D1; pin 1 of the sampling resistor R29 is connected to the phase-sensitive detection initial phase zeroing module, pin 2 is connected to resistor R31, and pin 3 is connected to resistor R30.

[0031] Further, the phase-sensitive detection initial phase zeroing module includes a relay K1, a relay K2, a relay K3, a relay K4, a diode D9, a diode D10, a diode D11, a diode D12, a sampling resistor R215, a resistor R216, a resistor R217, a resistor R218, a resistor R219, a resistor R220, a resistor R221, a resistor R222, a resistor R223, a MOS tube Q7, a MOS tube Q8, a MOS tube Q9 and a MOS tube Q10;

[0032] Pin 1 of the relay K1 is connected to pin 3 of the relay K3, pin 3 is connected to pin 1 of the relay K3, pin 5 is connected to the input end of the diode D9 and the drain of the MOS tube Q7, pin 6 is connected to the output end of the diode D9, pin 6 of the relay K2 and the output end of the diode D10, pin 7 is connected to pin 2 of the sampling resistor R215, and pin 8 is connected to pin 3 of the sampling resistor R215; the gate of the MOS tube Q7 is connected to the resistor R216 and the resistor R218, and the source is connected to the resistor R218 and grounded; the resistor R216 is connected to the MCU module;

[0033] Pin 1 of the relay K2 is connected to pin 3 of the relay K4, pin 3 is connected to pin 1 of the relay K4, pin 5 is connected to the input end of the diode D10 and the drain of the MOS tube Q8, pin 7 is connected to pin 1 of the sampling resistor R215, and pin 8 is connected to pin 4 of the sampling resistor R215; the gate of the MOS tube Q8 is connected to the resistor R217 and the resistor R219, and the source is connected to the resistor R219 and grounded; the resistor R217 is connected to the MCU module;

[0034] Pin 5 of the relay K3 is connected to the input end of the diode D11 and the drain of the MOS tube Q9, pin 6 is connected to the output end of the diode D11, and pins 7 and 8 are connected to the voltage-to-current module; the gate of the MOS tube Q9 is connected to the resistor R220 and the resistor R221, and the source is connected to the resistor R221 and grounded; the resistor R220 is connected to the MCU module;

[0035] Pin 5 of the relay K4 is connected to the input end of the diode D12 and the drain of the MOS tube Q10, pin 6 is connected to the output end of the diode D12, and pins 7 and 8 are connected to the sampling signal conversion module; the gate of the MOS tube Q10 is connected to the resistor R222 and the resistor R223, and the source is connected to the resistor R223 and grounded; the resistor R222 is connected to the MCU module.

[0036] Further, the sampling signal conversion module includes an operational amplifier U12A, an operational amplifier U17A, an operational amplifier U17B, a clamping diode D6, a clamping diode D7, a capacitor C40, a capacitor C51, a resistor R72, a resistor R73, a resistor R75, a resistor R77, a resistor R82, a resistor R104, a resistor R105, a resistor R108 and a resistor R110;

[0037] Pin 5 of the operational amplifier U17B is connected to resistor R75, resistor R77 and clamping diode D6, and pins 6 and 7 are connected to resistor R72; one end of the capacitor C40 is connected to resistor R75, and the other end is connected to the phase-sensitive detection initial phase zeroing module;

[0038] Pin 3 of the operational amplifier U17A is connected to resistor R108, resistor R110 and clamping diode D7, and pins 1 and 2 are connected to resistor R104; one end of the capacitor C51 is connected to resistor R108, and the other end is connected to the phase-sensitive detection initial phase zeroing module;

[0039] Pin 1 of the operational amplifier U12A is connected to the resistor R82 , the resistor R105 and the sampling signal gain module, pin 2 is connected to the resistor R104 and the resistor R105 , and pin 3 is connected to the resistor R72 and the resistor R73 .

[0040] Further, the sampling signal phase-sensitive detection module includes a single-channel single-pole double-throw analog switch U23, an operational amplifier U15B, an operational amplifier U25A, an operational amplifier U26, a resistor R85, a resistor R88, a resistor R89, a resistor R106, a resistor R109, a resistor R118, a resistor R120, a resistor R121, a resistor R122, a resistor R123, a capacitor C52 and a capacitor C55;

[0041] Pin 5 of the operational amplifier U15B is connected to the sampling signal bandpass filter module, and pins 6 and 7 are connected to resistor R106 and pin 2 of the single-channel single-pole double-throw analog switch U23; Pin 1 of the operational amplifier U25A is connected to resistor R85 and pin 8 of the single-channel single-pole double-throw analog switch U23, and pin 2 is connected to resistor R85 and resistor R106; Pin 1 of the single-channel single-pole double-throw analog switch U23 is connected to resistor R109, and pin 6 is connected to the MCU module;

[0042] Pin 1 of the operational amplifier U26 is connected to resistor R120 and resistor R122, pin 2 is connected to resistor R118 and capacitor C55, pin 4 is connected to resistor R121 and resistor R122, pin 5 is connected to resistor R88 and resistor R89, pin 6 is grounded, pin 7 is connected to resistor R123, and pin 8 is connected to resistor R89 ​​and resistor R109; capacitor C55 is connected to resistor R120 and grounded;

[0043] One end of the capacitor C52 is connected to the resistor R88 and the ADC module, and the other end is connected to the resistor R121 and the ADC module.

[0044] Further, the sampling signal self-calibration module includes an operational amplifier U14, an operational amplifier U15A, an operational amplifier U16, a resistor R46, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R67, a resistor R68, a resistor R69, a resistor R71, a resistor R78, a resistor R79, a resistor R80, a capacitor C33, a capacitor C36, a capacitor C37 and a capacitor C49;

[0045] Pin 1 of the operational amplifier U14 is connected to resistor R58 and resistor R60, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C36 is connected to resistor R58 and grounded; one end of the capacitor C33 is connected to resistor R46 and the ADC module, and the other end is connected to resistor R59 and the ADC module;

[0046] Pin 1 of the operational amplifier U16 is connected to resistor R71 and resistor R79, pin 2 is connected to resistor R69 and capacitor C49, pin 4 is connected to resistor R78 and resistor R79, pin 5 is connected to resistor R63 and resistor R64, pin 6 is grounded, pin 7 is connected to resistor R80, and pin 8 is connected to resistor R64 and resistor R67; capacitor C49 is connected to resistor R71 and grounded; one end of the capacitor C37 is connected to resistor R63 and the ADC module, and the other end is connected to resistor R78 and the ADC module;

[0047] One end of the resistor R62 is connected to the resistor R56, and the other end is grounded; pins 1 and 2 of the operational amplifier U15A are connected to the resistor R67, and pin 3 is connected to the resistor R65 and the resistor R68; the resistor R65 is connected to the DAC module;

[0048] The sampling signal full-wave rectification module includes an operational amplifier U25B, an operational amplifier U28, an operational amplifier U29A, a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128, a resistor R129, a resistor R130, a resistor R131, a resistor R132, a resistor R133, a resistor R134, a resistor R135, a resistor R136, a resistor R137, a resistor R138, a resistor R139, a resistor R140, a capacitor C64 and a capacitor C67;

[0049] Pin 1 of the operational amplifier U28 is connected to resistor R133 and resistor R136, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C67 is connected to resistor R133 and grounded; one end of capacitor C64 is connected to resistor R127 and ADC module, and the other end is connected to resistor R135 and ADC module;

[0050] Pin 5 of the operational amplifier U25B is connected to resistor R138, pin 6 is connected to resistor R124, resistor R125 and resistor R126, and pin 7 is connected to resistor R125, resistor R132 and resistor R130; pin 1 of the operational amplifier U29A is connected to resistor R129, resistor R138 and resistor R139, pin 2 is connected to resistor R129, and pin 3 is connected to resistor R134 and resistor R140; the resistor R134 is connected to resistor R124 and a sampling signal bandpass filter module.

[0051] The advantages of the present invention are:

[0052] The DAC module is used to output AC signals of different frequencies, a DAC signal bandpass filter module including a plurality of multiplexed analog switches is set to set the passband, a DAC signal gain module including a multiplexed analog switch is set to control the amplitude gain of the AC signal, a sampling signal gain module including a multiplexed analog switch is set to control the amplitude gain of the sampling signal, a voltage conversion current module including an integral proportional adjustment circuit is set to generate an AC constant current signal (constant current control of an AC constant current test signal), a phase-sensitive detection initial phase zeroing module with a built-in sampling resistor is set to perform an initial phase zeroing action of phase-sensitive detection, the AC signal of the lithium battery to be tested is differentially sampled through the sampling signal conversion module to obtain a corresponding AC response signal, a sampling signal full-wave rectification module and a sampling signal phase-sensitive detection module are set to synchronously obtain full-wave rectification and phase-sensitive detection, and then the real impedance and imaginary impedance corresponding to the AC internal resistance of the lithium battery to be tested, as well as the phase difference and the module value of the AC internal resistance are quickly obtained, the reference signal and the test signal are synchronously sampled through the ADC module to perform real-time calibration, and finally the AC internal resistance of the lithium battery at different frequencies is quickly and stably obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0054] Figure 1 The invention discloses a circuit principle block diagram of a lithium battery AC internal resistance detection system.

[0055] Figure 2 It is a circuit diagram of the MCU module of the present invention.

[0056] Figure 3 It is a circuit diagram of a DAC module and a DAC signal conversion module of the present invention.

[0057] Figure 4 It is a circuit diagram of the DAC signal bandpass filtering module of the present invention.

[0058] Figure 5 It is a circuit diagram of the DAC signal gain module of the present invention.

[0059] Figure 6 It is a circuit diagram of a DAC signal high-pass filter module and a voltage-to-current module of the present invention.

[0060] Figure 7 It is a circuit diagram of the phase-sensitive detection initial phase zeroing module of the present invention.

[0061] Figure 8 It is a circuit diagram of a sampling signal conversion module and a sampling signal gain module of the present invention.

[0062] Fig. 9 It is a circuit diagram of the sampling signal bandpass filtering module of the present invention.

[0063] Fig.10 It is a circuit diagram of the sampling signal phase-sensitive detection module of the present invention.

[0064] Fig.11 It is a circuit diagram of the ADC module of the present invention.

[0065] Fig.12 It is a circuit diagram of the sampling signal self-calibration module of the present invention.

[0066] Fig.13 It is a circuit diagram of the sampling signal full-wave rectification module of the present invention. DETAILED DESCRIPTION

[0067] The embodiment of the present invention solves the technical problem in the prior art that there is no way to quickly and stably obtain the AC internal resistance of a lithium battery at different frequencies by providing a lithium battery AC internal resistance detection system, thereby achieving the technical effect of quickly and stably obtaining the AC internal resistance of a lithium battery at different frequencies.

[0068] The technical solution in the embodiment of the present invention is to solve the above problems. The overall idea is as follows: output AC signals of different frequencies through a DAC module, set multiple multiplexing analog switches to set the passband and amplitude gain control, set a sampling signal full-wave rectification module and a sampling signal phase-sensitive detection module to synchronously obtain full-wave rectification and phase-sensitive detection, and then quickly obtain the real impedance and imaginary impedance corresponding to the AC internal resistance of the lithium battery to be tested, as well as the phase difference and the modulus value of the AC internal resistance, and synchronously sample the reference signal and the test signal through the ADC module for real-time calibration, so as to quickly and stably obtain the AC internal resistance of the lithium battery at different frequencies.

[0069] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0070] Please refer to Figures 1 to 13 As shown, a preferred embodiment of a lithium battery AC internal resistance detection system of the present invention includes an MCU module, a DAC module, a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a voltage-to-current module, a phase-sensitive detection initial phase zeroing module, a sampling signal conversion module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module, an ADC module, a sampling signal self-calibration module and a sampling signal full-wave rectification module;

[0071] The MCU module is used to communicate with the host computer to obtain corresponding setting items and test items for AC internal resistance detection, control the level output of the DAC module, control the DAC signal conversion module to convert the current signal into an AC voltage signal, control the passband of the DAC signal bandpass filter module, control the gain size of the DAC signal gain module, control the lower limit cutoff frequency of the DAC signal high-pass filter module, control the enable switch of the phase-sensitive detection initial phase zeroing module, control the gain size of the sampling signal gain module, control the passband of the sampling signal bandpass filter module, provide the sampling signal phase-sensitive detection module with a modulation signal of phase-sensitive detection, process the digital signal from the ADC module and transmit it to the host computer via Ethernet. In specific implementation, it is sufficient to select an MCU module that can realize this function from the prior art, and it is not limited to any model, such as ARM's TM4C1294, and the control program is well known to those skilled in the art, which can be obtained by those skilled in the art without creative labor.

[0072] The DAC module is used to output a specific signal quantity with high precision according to the signal transmitted by the MCU module, and provide it to the DAC signal conversion module for use, and the reference voltage source is provided to the sampling signal self-calibration module and the ADC module for use. The model of the DAC module is preferably AD5453; the DAC signal conversion module is used to convert the current signal output by the DAC module into an AC voltage signal; the DAC signal bandpass filter module is used to switch the bandpass filter circuit to a passband corresponding to the current test frequency through the multiplexed analog switch U1, the multiplexed analog switch U2, the multiplexed analog switch U4, and the multiplexed analog switch U8 according to the control signal of the MCU module; the DAC signal gain module is used to The control signal of the MCU module switches the signal gain in the circuit to the corresponding gear through the multiplexing analog switch U11; the DAC signal high-pass filter module is used to adjust the lower limit cutoff frequency through the multiplexing analog switch U13 based on the current test frequency according to the control signal of the MCU module; the voltage-to-current module is used to convert the AC constant voltage signal into the corresponding AC constant current signal to be used as the excitation source of the lithium battery to be tested; the phase-sensitive detection initial phase zeroing module has an internal integrated sampling resistor R215, and controls the relays K1, K2, K3, and K4 according to the control signal of the MCU module to perform the phase-sensitive detection initial phase zeroing action; the sampling signal conversion module Used to collect the AC voltage signal of the lithium battery to be tested; the circuit structure of the sampling signal gain module is the same as the circuit structure of the DAC signal gain module, and is used to switch the signal gain in the circuit to the corresponding gear through the multiplexing analog switch U24 according to the control signal of the MCU module; the circuit structure of the sampling signal bandpass filter module is the same as the circuit structure of the DAC signal bandpass filter module, and is used to switch the bandpass filter circuit to the passband corresponding to the current test frequency through the multiplexing analog switch U19, the multiplexing analog switch U20, the multiplexing analog switch U22, and the multiplexing analog switch U27 according to the control signal of the MCU module; the sampling signal phase-sensitive detection module is used to bandpass filter the sampling signal The signal output by the module is modulated by the phase-sensitive detection signal and then output to the ADC module for sampling; the ADC module is used to synchronously sample the signals transmitted by the sampling signal phase-sensitive detection module, the sampling signal full-wave rectification module, and the sampling signal self-calibration module, and convert them into digital quantities and transmit them to the MCU module, and the model is preferably AD4134; the sampling signal self-calibration module is used to provide the reference source signal and the ground level signal to the ADC module for sampling, and the MCU module performs real-time calibration on the sampling result of the test signal based on the sampling result of the reference; the sampling signal full-wave rectification module is used to pass the signal provided by the sampling signal bandpass filtering module through a full-wave rectification circuit, and output the corresponding full-wave rectification signal to the ADC module for sampling.

[0073] The MCU module, DAC module, DAC signal conversion module, DAC signal bandpass filter module, DAC signal gain module, DAC signal high-pass filter module, voltage-to-current module, phase-sensitive detection initial phase zeroing module, sampling signal conversion module, sampling signal gain module, sampling signal bandpass filter module, sampling signal phase-sensitive detection module and ADC module are connected in sequence;

[0074] The MCU modules are respectively connected to a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a phase-sensitive detection initial phase zeroing module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module and an ADC module;

[0075] The DAC module is connected to the ADC module and the sampling signal self-calibration module respectively; the ADC module is connected to the sampling signal self-calibration module; one end of the sampling signal full-wave rectification module is connected to the ADC module, and the other end is connected to the sampling signal bandpass filtering module.

[0076] The DAC signal conversion module includes a digital-to-analog converter U7, an operational amplifier U3A, an operational amplifier U5B, a resistor R3, a resistor R4, a resistor R8, a resistor R9, a resistor R14, a resistor R24 ​​and a capacitor C11; the model of the digital-to-analog converter U7 is preferably AD5453;

[0077] Pin 1 of the digital-to-analog converter U7 is connected to capacitor C11 and pin 6 of op amp U5B, pin 2 is connected to pin 5 of op amp U5B and grounded, pins 3, 4, and 5 are all connected to the MCU module, pin 7 is connected to the DAC module, and pin 8 is connected to resistor R8; pin 7 of the op amp U5B is connected to resistor R8, resistor R9, resistor R14, and capacitor C11; one end of the resistor R3 is connected to the DAC module, and the other end is connected to resistor R4, resistor R9, and pin 2 of op amp U3A; pin 1 of the op amp U3A is connected to resistor R4, resistor R24, and a DAC signal bandpass filter module.

[0078] The DAC signal bandpass filter module includes a multiplexed analog switch U1, a multiplexed analog switch U2, a multiplexed analog switch U4, a multiplexed analog switch U8, a resistor R1, a resistor R2, a resistor R5, a resistor R6, a resistor R7, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R 25. A resistor R37, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C14, a capacitor C15, a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21, an operational amplifier U5A and an operational amplifier U3B; the models of the multiplexing analog switch U1, the multiplexing analog switch U2, the multiplexing analog switch U4 and the multiplexing analog switch U8 are preferably MAX308;

[0079] One end of the resistor R13 is connected to the DAC signal conversion module, and the other end is connected to the resistor R15, the resistor R16, the resistor R17, the resistor R18, the resistor R19, the resistor R20, the resistor R21, the resistor R22, the pin 8 of the multiplexed analog switch U8, and the pin 3 of the operational amplifier U5A;

[0080] Pins 9, 10, 11, 12, 7, 6, 5, and 4 of the multiplexed analog switch U1 are respectively connected to resistors R15, R16, R17, R18, R19, R20, R21, and R22, pin 8 is connected to pin 8 of the multiplexed analog switch U2 and pin 7 of the operational amplifier U3B, and pins 1, 2, 15, and 16 are connected to the MCU module;

[0081] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U2 are connected to capacitors C1, C2, C3, C4, C5, C6, C7, and C8, respectively, and pins 1, 2, 15, and 16 are connected to the MCU module;

[0082] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U4 are connected to resistors R5, R6, R7, R10, R11, R12, R23, and R25, respectively; pin 8 is connected to capacitors C1, C2, C3, C4, C5, C6, C7, C8, pin 6 of op amp U3B, and pin 2 of op amp U5A; and pins 1, 2, 15, and 16 are connected to the MCU module;

[0083] One ends of the capacitors C14, C15, C16, C17, C18, C19, C20 and C21 are connected to each other and grounded, and the other ends are connected to pins 9, 10, 11, 12, 7, 6, 5 and 4 of the multiplex analog switch U8 respectively; pins 1, 2, 15 and 16 of the multiplex analog switch U8 are connected to the MCU module;

[0084] Pin 5 of the operational amplifier U3B is connected to resistor R1 and resistor R2; one end of the resistor R37 is connected to the DAC signal gain module, and the other end is connected to resistor R2, resistor R5, resistor R6, resistor R7, resistor R10, resistor R11, resistor R12, resistor R23, resistor R25 and pin 1 of the operational amplifier U5A.

[0085] The DAC signal gain module includes a multiplexed analog switch U11, an operational amplifier U10B, a resistor R38, a resistor R40, a resistor R41, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53 and a resistor R54; the model of the multiplexed analog switch U11 is preferably MUX509;

[0086] One end of the resistor R41 is connected to the DAC signal high-pass filter module, and the other end is connected to the resistor R38, the resistor R47, the resistor R48, the resistor R49, the resistor R50 and the pin 7 of the operational amplifier U10B; the pin 5 of the operational amplifier U10B is connected to the pin 9 of the multiplexing analog switch U11 and the DAC signal band-pass filter module, and the pin 6 is connected to the resistor R40 and the pin 8 of the multiplexing analog switch U11;

[0087] Pins 4, 5, 6, 7, 13, 12, 11, and 10 of the multiplexed analog switch U11 are respectively connected to resistors R47, R48, R49, R50, R51, R52, R53, and R54, and pins 1, 2, and 16 are connected to the MCU module; one ends of the resistors R51, R52, R53, and R54 are interconnected and grounded.

[0088] The DAC signal high-pass filter module includes a multiplexed analog switch U13, an operational amplifier U10A, an operational amplifier U12B, a resistor R33, a resistor R34, a resistor R42, a resistor R44, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31 and a capacitor C32; the model of the multiplexed analog switch U13 is preferably MAX308;

[0089] Pin 1 of the operational amplifier U10A is connected to the resistor R33, the resistor R42 and the voltage-to-current module, pin 2 is connected to the resistor R33 and the resistor R34, and pin 3 is connected to the resistor R44 and the DAC signal gain module;

[0090] Pin 6 of the operational amplifier U12B is connected to the resistor R42 and the pin 8 of the multiplexing analog switch U13, and pin 7 is connected to the resistor R44, the capacitor C25, the capacitor C26, the capacitor C27, the capacitor C28, the capacitor C29, the capacitor C30, the capacitor C31 and the capacitor C32;

[0091] Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U13 are respectively connected to capacitors C25, C26, C27, C28, C29, C30, C31, and C32, and pins 1, 2, 15, and 16 are connected to the MCU module.

[0092] The voltage-to-current module includes an operational amplifier U9A, an operational amplifier U9B, a clamping diode D1, a clamping diode D3, a clamping diode D4, a diode D2, a diode D5, a sampling resistor R29, a resistor R27, a resistor R28, a resistor R30, a resistor R31, a resistor R32, a resistor R35, a resistor R36, a resistor R39, a resistor R43, a resistor R45, a resistor R213, a capacitor C22, a capacitor C23, a capacitor C24, a transistor Q1, a transistor Q2, a transistor Q3 and a transistor Q4;

[0093] One end of the resistor R39 is connected to the DAC signal high-pass filter module, and the other end is connected to pin 3 of the operational amplifier U9A; pin 2 of the operational amplifier U9A is connected to resistor R36, capacitor C22 and capacitor C23, and pin 1 is connected to resistor R32 and resistor R213; the resistor R32 is connected to capacitor C22; the resistor R36 is connected to capacitor C23, resistor R27 and pin 7 of the operational amplifier U9B;

[0094] The input end of the diode D2 is connected to the resistor R28 and the b-pole of the transistor Q2, and the output end is connected to the resistor R213 and the input end of the diode D5; the output end of the diode D5 is connected to the resistor R43 and the b-pole of the transistor Q4;

[0095] The c-pole of the transistor Q2 is connected to the resistor R28, and the e-pole is connected to the b-pole of the transistor Q1; the c-pole of the transistor Q4 is connected to the resistor R43, and the e-pole is connected to the b-pole of the transistor Q3; one end of the resistor R45 is connected to the capacitor C24, and the other end is connected to the clamping diode D4, the e-pole of the transistor Q1 and the e-pole of the transistor Q3; the capacitor C24 is connected to the phase-sensitive detection initial phase zeroing module;

[0096] Pin 5 of the operational amplifier U9B is connected to resistor R31, resistor R35 and clamping diode D3, and pin 6 is connected to resistor R27, resistor R30 and clamping diode D1; pin 1 of the sampling resistor R29 is connected to the phase-sensitive detection initial phase zeroing module, pin 2 is connected to resistor R31, and pin 3 is connected to resistor R30.

[0097] The phase-sensitive detection initial phase zeroing module includes a relay K1, a relay K2, a relay K3, a relay K4, a diode D9, a diode D10, a diode D11, a diode D12, a sampling resistor R215, a resistor R216, a resistor R217, a resistor R218, a resistor R219, a resistor R220, a resistor R221, a resistor R222, a resistor R223, a MOS tube Q7, a MOS tube Q8, a MOS tube Q9 and a MOS tube Q10; the models of the relay K1, the relay K2, the relay K3 and the relay K4 are preferably HFD4 / 12;

[0098] Pin 1 of the relay K1 is connected to pin 3 of the relay K3, pin 3 is connected to pin 1 of the relay K3, pin 5 is connected to the input end of the diode D9 and the drain of the MOS tube Q7, pin 6 is connected to the output end of the diode D9, pin 6 of the relay K2 and the output end of the diode D10, pin 7 is connected to pin 2 of the sampling resistor R215, and pin 8 is connected to pin 3 of the sampling resistor R215; the gate of the MOS tube Q7 is connected to the resistor R216 and the resistor R218, and the source is connected to the resistor R218 and grounded; the resistor R216 is connected to the MCU module;

[0099] Pin 1 of the relay K2 is connected to pin 3 of the relay K4, pin 3 is connected to pin 1 of the relay K4, pin 5 is connected to the input end of the diode D10 and the drain of the MOS tube Q8, pin 7 is connected to pin 1 of the sampling resistor R215, and pin 8 is connected to pin 4 of the sampling resistor R215; the gate of the MOS tube Q8 is connected to the resistor R217 and the resistor R219, and the source is connected to the resistor R219 and grounded; the resistor R217 is connected to the MCU module;

[0100] Pin 5 of the relay K3 is connected to the input end of the diode D11 and the drain of the MOS tube Q9, pin 6 is connected to the output end of the diode D11, and pins 7 and 8 are connected to the voltage-to-current module; the gate of the MOS tube Q9 is connected to the resistor R220 and the resistor R221, and the source is connected to the resistor R221 and grounded; the resistor R220 is connected to the MCU module;

[0101] Pin 5 of the relay K4 is connected to the input end of the diode D12 and the drain of the MOS tube Q10, pin 6 is connected to the output end of the diode D12, and pins 7 and 8 are connected to the sampling signal conversion module; the gate of the MOS tube Q10 is connected to the resistor R222 and the resistor R223, and the source is connected to the resistor R223 and grounded; the resistor R222 is connected to the MCU module.

[0102] The sampling signal conversion module includes an operational amplifier U12A, an operational amplifier U17A, an operational amplifier U17B, a clamping diode D6, a clamping diode D7, a capacitor C40, a capacitor C51, a resistor R72, a resistor R73, a resistor R75, a resistor R77, a resistor R82, a resistor R104, a resistor R105, a resistor R108 and a resistor R110;

[0103] Pin 5 of the operational amplifier U17B is connected to resistor R75, resistor R77 and clamping diode D6, and pins 6 and 7 are connected to resistor R72; one end of the capacitor C40 is connected to resistor R75, and the other end is connected to the phase-sensitive detection initial phase zeroing module;

[0104] Pin 3 of the operational amplifier U17A is connected to resistor R108, resistor R110 and clamping diode D7, and pins 1 and 2 are connected to resistor R104; one end of the capacitor C51 is connected to resistor R108, and the other end is connected to the phase-sensitive detection initial phase zeroing module;

[0105] Pin 1 of the operational amplifier U12A is connected to the resistor R82 , the resistor R105 and the sampling signal gain module, pin 2 is connected to the resistor R104 and the resistor R105 , and pin 3 is connected to the resistor R72 and the resistor R73 .

[0106] The sampling signal phase-sensitive detection module includes a single-channel single-pole double-throw analog switch U23, an operational amplifier U15B, an operational amplifier U25A, an operational amplifier U26, a resistor R85, a resistor R88, a resistor R89, a resistor R106, a resistor R109, a resistor R118, a resistor R120, a resistor R121, a resistor R122, a resistor R123, a capacitor C52 and a capacitor C55; the model of the single-channel single-pole double-throw analog switch U23 is preferably ADG619; the model of the operational amplifier U26 is preferably THS4531;

[0107] Pin 5 of the operational amplifier U15B is connected to the sampling signal bandpass filter module, and pins 6 and 7 are connected to resistor R106 and pin 2 of the single-channel single-pole double-throw analog switch U23; Pin 1 of the operational amplifier U25A is connected to resistor R85 and pin 8 of the single-channel single-pole double-throw analog switch U23, and pin 2 is connected to resistor R85 and resistor R106; Pin 1 of the single-channel single-pole double-throw analog switch U23 is connected to resistor R109, and pin 6 is connected to the MCU module;

[0108] Pin 1 of the operational amplifier U26 is connected to resistor R120 and resistor R122, pin 2 is connected to resistor R118 and capacitor C55, pin 4 is connected to resistor R121 and resistor R122, pin 5 is connected to resistor R88 and resistor R89, pin 6 is grounded, pin 7 is connected to resistor R123, and pin 8 is connected to resistor R89 ​​and resistor R109; capacitor C55 is connected to resistor R120 and grounded;

[0109] One end of the capacitor C52 is connected to the resistor R88 and the ADC module, and the other end is connected to the resistor R121 and the ADC module.

[0110] The sampling signal self-calibration module includes an operational amplifier U14, an operational amplifier U15A, an operational amplifier U16, a resistor R46, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R67, a resistor R68, a resistor R69, a resistor R71, a resistor R78, a resistor R79, a resistor R80, a capacitor C33, a capacitor C36, a capacitor C37 and a capacitor C49;

[0111] Pin 1 of the operational amplifier U14 is connected to resistor R58 and resistor R60, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C36 is connected to resistor R58 and grounded; one end of the capacitor C33 is connected to resistor R46 and the ADC module, and the other end is connected to resistor R59 and the ADC module;

[0112] Pin 1 of the operational amplifier U16 is connected to resistor R71 and resistor R79, pin 2 is connected to resistor R69 and capacitor C49, pin 4 is connected to resistor R78 and resistor R79, pin 5 is connected to resistor R63 and resistor R64, pin 6 is grounded, pin 7 is connected to resistor R80, and pin 8 is connected to resistor R64 and resistor R67; capacitor C49 is connected to resistor R71 and grounded; one end of the capacitor C37 is connected to resistor R63 and the ADC module, and the other end is connected to resistor R78 and the ADC module;

[0113] One end of the resistor R62 is connected to the resistor R56, and the other end is grounded; pins 1 and 2 of the operational amplifier U15A are connected to the resistor R67, and pin 3 is connected to the resistor R65 and the resistor R68; the resistor R65 is connected to the DAC module;

[0114] The sampling signal full-wave rectification module includes an operational amplifier U25B, an operational amplifier U28, an operational amplifier U29A, a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128, a resistor R129, a resistor R130, a resistor R131, a resistor R132, a resistor R133, a resistor R134, a resistor R135, a resistor R136, a resistor R137, a resistor R138, a resistor R139, a resistor R140, a capacitor C64 and a capacitor C67;

[0115] Pin 1 of the operational amplifier U28 is connected to resistor R133 and resistor R136, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C67 is connected to resistor R133 and grounded; one end of capacitor C64 is connected to resistor R127 and ADC module, and the other end is connected to resistor R135 and ADC module;

[0116] Pin 5 of the operational amplifier U25B is connected to resistor R138, pin 6 is connected to resistor R124, resistor R125 and resistor R126, and pin 7 is connected to resistor R125, resistor R132 and resistor R130; pin 1 of the operational amplifier U29A is connected to resistor R129, resistor R138 and resistor R139, pin 2 is connected to resistor R129, and pin 3 is connected to resistor R134 and resistor R140; the resistor R134 is connected to resistor R124 and a sampling signal bandpass filter module.

[0117] Working principle of the present invention:

[0118] The host computer sets at least the detection parameters including the frequency range of the lithium battery AC internal resistance to be detected, the excitation current used for detection, the frequency step value of the detection, the step interval time, whether the phase-sensitive detection initial phase zeroing module is enabled, and the resistance range of the AC internal resistance of the lithium battery to be tested, and sends the detection parameters to the MCU module.

[0119] The MCU module calculates the received detection parameters to obtain the relationship between the output value of the DAC module and time under different AC frequencies and amplitudes, the configurations of the DAC signal bandpass filter module, the sampling signal bandpass filter module, and the DAC signal high-pass filter module under different frequencies, and the different configurations of the DAC signal gain module and the sampling signal gain module under different signal amplitudes, and conveys the configurations to the corresponding modules.

[0120] Based on the detection instruction sent by the MCU module, the DAC module outputs a signal that matches the current test frequency and signal amplitude and changes with time; the signal output by the DAC module passes through the DAC signal conversion module to form an AC voltage signal corresponding to the test frequency and test amplitude, and the AC voltage signal passes through the DAC signal bandpass filter module preset according to the current frequency by the MCU module to output the AC voltage signal after bandpass filtering, and then passes through the DAC signal gain module for signal gain processing, and then passes through the DAC signal high-pass filter module with a cut-off frequency preset by the MCU module according to the current test frequency to eliminate the additional DC voltage component in the AC voltage signal and transmit it to the voltage conversion current module, and the AC voltage signal (AC constant voltage signal) provided by the previous stage is converted into an AC constant current signal through the integral proportional adjustment circuit in the voltage conversion current module.

[0121] The MCU module determines whether to perform the initial phase zeroing action of the phase-sensitive detection according to the detection parameters sent by the host computer. If zeroing is required, the initial phase zeroing action is performed: the MCU module controls relays K1 and K2 to be in normally open contacts, and relays K3 and K4 to be in normally closed contacts, and transmits the excitation and sampling signals (AC voltage signals) to the sampling resistor R215 of the initial phase zeroing module of the phase-sensitive detection, and then obtains the analog signal generated after full-wave rectification and phase-sensitive detection from the ADC module in real time, and adjusts the phase value of the phase-sensitive detection modulation signal of the sampling signal phase-sensitive detection module in real time through the control pin 74 until the signal collected by the ADC module is consistent with the sampling value processed by the sampling signal full-wave rectification module and the sampling signal phase-sensitive detection module, and the initial phase zeroing of the phase-sensitive detection is completed, and then the AC internal resistance detection of the lithium battery to be tested is performed; if zeroing is not required, the MCU module controls relays K3 and K4 to be in normally open contacts, and relays K1 and K2 to be in normally closed contacts, and directly performs the AC internal resistance detection of the lithium battery to be tested.

[0122] The sampling signal conversion module performs differential sampling from the positive and negative ends of the lithium battery to be tested, obtains the AC voltage signal generated by the lithium battery to be tested under the excitation of the AC constant current signal at the corresponding frequency, and then transmits the obtained AC voltage signal to the sampling signal gain module. The sampling signal gain module amplifies the AC voltage signal and inputs it into the sampling signal bandpass filter module for bandpass filtering. The processed AC voltage signal is respectively transmitted to the sampling signal full-wave rectification module and the sampling signal phase-sensitive detection module for signal processing. Finally, the signal after full-wave rectification and phase-sensitive detection modulation is transmitted to the ADC module. The reference power supply used by the ADC module and the DAC module is also transmitted to the ADC module after signal attenuation processing. The ADC module synchronously samples the signal of the corresponding sampling pin, converts the sampled analog signal into the corresponding digital quantity, and transmits it to the MCU module.

[0123] The MCU module calibrates the full-wave rectified sampling signal and phase-sensitive detection sampling signal provided by the ADC module in real time according to the reference voltage sampling signal obtained from the ADC module, so as to further improve the sampling accuracy and stability. Then, the different results of the signal after full-wave rectification and phase-sensitive detection are converted to obtain the real impedance and imaginary impedance corresponding to the AC internal resistance of the lithium battery under different test frequency states, as well as the phase difference and the modulus value of the AC internal resistance. Then, the calculation results are transmitted back to the host computer through Ethernet. The host computer depicts the electrochemical impedance spectrum information according to the obtained calculation results, and finally presents it dynamically on the test interface in the form of Nyquist diagram and Bode diagram during the test process. After the test, the user can select the corresponding area on the test interface to dynamically zoom in and view the test parameters in more detail, or directly export the corresponding test parameters to an Excel table through the host computer. After each test, the host computer will automatically save the test data of the current test to facilitate later traceability.

[0124] In summary, the advantages of the present invention are:

[0125] The DAC module is used to output AC signals of different frequencies, a DAC signal bandpass filter module including a plurality of multiplexed analog switches is set to set the passband, a DAC signal gain module including a multiplexed analog switch is set to control the amplitude gain of the AC signal, a sampling signal gain module including a multiplexed analog switch is set to control the amplitude gain of the sampling signal, a voltage conversion current module including an integral proportional adjustment circuit is set to generate an AC constant current signal (constant current control of an AC constant current test signal), a phase-sensitive detection initial phase zeroing module with a built-in sampling resistor is set to perform an initial phase zeroing action of phase-sensitive detection, the AC signal of the lithium battery to be tested is differentially sampled through the sampling signal conversion module to obtain a corresponding AC response signal, a sampling signal full-wave rectification module and a sampling signal phase-sensitive detection module are set to synchronously obtain full-wave rectification and phase-sensitive detection, and then the real impedance and imaginary impedance corresponding to the AC internal resistance of the lithium battery to be tested, as well as the phase difference and the module value of the AC internal resistance are quickly obtained, the reference signal and the test signal are synchronously sampled through the ADC module to perform real-time calibration, and finally the AC internal resistance of the lithium battery at different frequencies is quickly and stably obtained.

[0126] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A lithium battery AC internal resistance detection system, Features: It includes an MCU module, a DAC module, a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a voltage-to-current module, a phase-sensitive detection initial phase zero adjustment module, a sampling signal conversion module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module, an ADC module, a sampling signal self-calibration module and a sampling signal full-wave rectification module; The MCU module, DAC module, DAC signal conversion module, DAC signal bandpass filter module, DAC signal gain module, DAC signal high-pass filter module, voltage-to-current module, phase-sensitive detection initial phase zeroing module, sampling signal conversion module, sampling signal gain module, sampling signal bandpass filter module, sampling signal phase-sensitive detection module and ADC module are connected in sequence; The MCU modules are respectively connected to a DAC signal conversion module, a DAC signal bandpass filter module, a DAC signal gain module, a DAC signal high-pass filter module, a phase-sensitive detection initial phase zeroing module, a sampling signal gain module, a sampling signal bandpass filter module, a sampling signal phase-sensitive detection module and an ADC module; The DAC module is connected to the ADC module and the sampling signal self-calibration module respectively; the ADC module is connected to the sampling signal self-calibration module; one end of the sampling signal full-wave rectification module is connected to the ADC module, and the other end is connected to the sampling signal bandpass filtering module.

2. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The DAC signal conversion module includes a digital-to-analog converter U7, an operational amplifier U3A, an operational amplifier U5B, a resistor R3, a resistor R4, a resistor R8, a resistor R9, a resistor R14, a resistor R24 ​​and a capacitor C11; Pin 1 of the digital-to-analog converter U7 is connected to capacitor C11 and pin 6 of op amp U5B, pin 2 is connected to pin 5 of op amp U5B and grounded, pins 3, 4, and 5 are all connected to the MCU module, pin 7 is connected to the DAC module, and pin 8 is connected to resistor R8; pin 7 of the op amp U5B is connected to resistor R8, resistor R9, resistor R14, and capacitor C11; one end of the resistor R3 is connected to the DAC module, and the other end is connected to resistor R4, resistor R9, and pin 2 of op amp U3A; pin 1 of the op amp U3A is connected to resistor R4, resistor R24, and a DAC signal bandpass filter module.

3. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The DAC signal bandpass filter module includes a multiplexed analog switch U1, a multiplexed analog switch U2, a multiplexed analog switch U4, a multiplexed analog switch U8, a resistor R1, a resistor R2, a resistor R5, a resistor R6, a resistor R7, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R31, a resistor R32 A resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R25, a resistor R37, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C14, a capacitor C15, a capacitor C16, a capacitor C17, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21, an operational amplifier U5A, and an operational amplifier U3B; One end of the resistor R13 is connected to the DAC signal conversion module, and the other end is connected to the resistor R15, the resistor R16, the resistor R17, the resistor R18, the resistor R19, the resistor R20, the resistor R21, the resistor R22, the pin 8 of the multiplexed analog switch U8, and the pin 3 of the operational amplifier U5A; Pins 9, 10, 11, 12, 7, 6, 5, and 4 of the multiplexed analog switch U1 are respectively connected to resistors R15, R16, R17, R18, R19, R20, R21, and R22, pin 8 is connected to pin 8 of the multiplexed analog switch U2 and pin 7 of the operational amplifier U3B, and pins 1, 2, 15, and 16 are connected to the MCU module; Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U2 are connected to capacitors C1, C2, C3, C4, C5, C6, C7, and C8, respectively, and pins 1, 2, 15, and 16 are connected to the MCU module; Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U4 are connected to resistors R5, R6, R7, R10, R11, R12, R23, and R25, respectively; pin 8 is connected to capacitors C1, C2, C3, C4, C5, C6, C7, C8, pin 6 of op amp U3B, and pin 2 of op amp U5A; and pins 1, 2, 15, and 16 are connected to the MCU module; One ends of the capacitors C14, C15, C16, C17, C18, C19, C20 and C21 are connected to each other and grounded, and the other ends are connected to pins 9, 10, 11, 12, 7, 6, 5 and 4 of the multiplex analog switch U8 respectively; pins 1, 2, 15 and 16 of the multiplex analog switch U8 are connected to the MCU module; Pin 5 of the operational amplifier U3B is connected to resistor R1 and resistor R2; one end of the resistor R37 is connected to the DAC signal gain module, and the other end is connected to resistor R2, resistor R5, resistor R6, resistor R7, resistor R10, resistor R11, resistor R12, resistor R23, resistor R25 and pin 1 of the operational amplifier U5A.

4. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The DAC signal gain module includes a multiplexed analog switch U11, an operational amplifier U10B, a resistor R38, a resistor R40, a resistor R41, a resistor R47, a resistor R48, a resistor R49, a resistor R50, a resistor R51, a resistor R52, a resistor R53 and a resistor R54; One end of the resistor R41 is connected to the DAC signal high-pass filter module, and the other end is connected to the resistor R38, the resistor R47, the resistor R48, the resistor R49, the resistor R50 and the pin 7 of the operational amplifier U10B; the pin 5 of the operational amplifier U10B is connected to the pin 9 of the multiplexing analog switch U11 and the DAC signal band-pass filter module, and the pin 6 is connected to the resistor R40 and the pin 8 of the multiplexing analog switch U11; Pins 4, 5, 6, 7, 13, 12, 11, and 10 of the multiplexed analog switch U11 are respectively connected to resistors R47, R48, R49, R50, R51, R52, R53, and R54, and pins 1, 2, and 16 are connected to the MCU module; one ends of the resistors R51, R52, R53, and R54 are interconnected and grounded.

5. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The DAC signal high-pass filter module includes a multiplexed analog switch U13, an operational amplifier U10A, an operational amplifier U12B, a resistor R33, a resistor R34, a resistor R42, a resistor R44, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31 and a capacitor C32; Pin 1 of the operational amplifier U10A is connected to the resistor R33, the resistor R42 and the voltage-to-current module, pin 2 is connected to the resistor R33 and the resistor R34, and pin 3 is connected to the resistor R44 and the DAC signal gain module; Pin 6 of the operational amplifier U12B is connected to the resistor R42 and the pin 8 of the multiplexing analog switch U13, and pin 7 is connected to the resistor R44, the capacitor C25, the capacitor C26, the capacitor C27, the capacitor C28, the capacitor C29, the capacitor C30, the capacitor C31 and the capacitor C32; Pins 4, 5, 6, 7, 12, 11, 10, and 9 of the multiplexed analog switch U13 are respectively connected to capacitors C25, C26, C27, C28, C29, C30, C31, and C32, and pins 1, 2, 15, and 16 are connected to the MCU module.

6. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The voltage-to-current module includes an operational amplifier U9A, an operational amplifier U9B, a clamping diode D1, a clamping diode D3, a clamping diode D4, a diode D2, a diode D5, a sampling resistor R29, a resistor R27, a resistor R28, a resistor R30, a resistor R31, a resistor R32, a resistor R35, a resistor R36, a resistor R39, a resistor R43, a resistor R45, a resistor R213, a capacitor C22, a capacitor C23, a capacitor C24, a transistor Q1, a transistor Q2, a transistor Q3 and a transistor Q4; One end of the resistor R39 is connected to the DAC signal high-pass filter module, and the other end is connected to pin 3 of the operational amplifier U9A; pin 2 of the operational amplifier U9A is connected to resistor R36, capacitor C22 and capacitor C23, and pin 1 is connected to resistor R32 and resistor R213; the resistor R32 is connected to capacitor C22; the resistor R36 is connected to capacitor C23, resistor R27 and pin 7 of the operational amplifier U9B; The input end of the diode D2 is connected to the resistor R28 and the b-pole of the transistor Q2, and the output end is connected to the resistor R213 and the input end of the diode D5; the output end of the diode D5 is connected to the resistor R43 and the b-pole of the transistor Q4; The c-pole of the transistor Q2 is connected to the resistor R28, and the e-pole is connected to the b-pole of the transistor Q1; the c-pole of the transistor Q4 is connected to the resistor R43, and the e-pole is connected to the b-pole of the transistor Q3; one end of the resistor R45 is connected to the capacitor C24, and the other end is connected to the clamping diode D4, the e-pole of the transistor Q1 and the e-pole of the transistor Q3; the capacitor C24 is connected to the phase-sensitive detection initial phase zeroing module; Pin 5 of the operational amplifier U9B is connected to resistor R31, resistor R35 and clamping diode D3, and pin 6 is connected to resistor R27, resistor R30 and clamping diode D1; pin 1 of the sampling resistor R29 is connected to the phase-sensitive detection initial phase zeroing module, pin 2 is connected to resistor R31, and pin 3 is connected to resistor R30.

7. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The phase-sensitive detection initial phase zeroing module includes a relay K1, a relay K2, a relay K3, a relay K4, a diode D9, a diode D10, a diode D11, a diode D12, a sampling resistor R215, a resistor R216, a resistor R217, a resistor R218, a resistor R219, a resistor R220, a resistor R221, a resistor R222, a resistor R223, a MOS tube Q7, a MOS tube Q8, a MOS tube Q9 and a MOS tube Q10; Pin 1 of the relay K1 is connected to pin 3 of the relay K3, pin 3 is connected to pin 1 of the relay K3, pin 5 is connected to the input end of the diode D9 and the drain of the MOS tube Q7, pin 6 is connected to the output end of the diode D9, pin 6 of the relay K2 and the output end of the diode D10, pin 7 is connected to pin 2 of the sampling resistor R215, and pin 8 is connected to pin 3 of the sampling resistor R215; the gate of the MOS tube Q7 is connected to the resistor R216 and the resistor R218, and the source is connected to the resistor R218 and grounded; the resistor R216 is connected to the MCU module; Pin 1 of the relay K2 is connected to pin 3 of the relay K4, pin 3 is connected to pin 1 of the relay K4, pin 5 is connected to the input end of the diode D10 and the drain of the MOS tube Q8, pin 7 is connected to pin 1 of the sampling resistor R215, and pin 8 is connected to pin 4 of the sampling resistor R215; the gate of the MOS tube Q8 is connected to the resistor R217 and the resistor R219, and the source is connected to the resistor R219 and grounded; the resistor R217 is connected to the MCU module; Pin 5 of the relay K3 is connected to the input end of the diode D11 and the drain of the MOS tube Q9, pin 6 is connected to the output end of the diode D11, and pins 7 and 8 are connected to the voltage-to-current module; the gate of the MOS tube Q9 is connected to the resistor R220 and the resistor R221, and the source is connected to the resistor R221 and grounded; the resistor R220 is connected to the MCU module; Pin 5 of the relay K4 is connected to the input end of the diode D12 and the drain of the MOS tube Q10, pin 6 is connected to the output end of the diode D12, and pins 7 and 8 are connected to the sampling signal conversion module; the gate of the MOS tube Q10 is connected to the resistor R222 and the resistor R223, and the source is connected to the resistor R223 and grounded; the resistor R222 is connected to the MCU module.

8. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The sampling signal conversion module includes an operational amplifier U12A, an operational amplifier U17A, an operational amplifier U17B, a clamping diode D6, a clamping diode D7, a capacitor C40, a capacitor C51, a resistor R72, a resistor R73, a resistor R75, a resistor R77, a resistor R82, a resistor R104, a resistor R105, a resistor R108 and a resistor R110; Pin 5 of the operational amplifier U17B is connected to resistor R75, resistor R77 and clamping diode D6, and pins 6 and 7 are connected to resistor R72; one end of the capacitor C40 is connected to resistor R75, and the other end is connected to the phase-sensitive detection initial phase zeroing module; Pin 3 of the operational amplifier U17A is connected to resistor R108, resistor R110 and clamping diode D7, and pins 1 and 2 are connected to resistor R104; one end of the capacitor C51 is connected to resistor R108, and the other end is connected to the phase-sensitive detection initial phase zeroing module; Pin 1 of the operational amplifier U12A is connected to the resistor R82 , the resistor R105 and the sampling signal gain module, pin 2 is connected to the resistor R104 and the resistor R105 , and pin 3 is connected to the resistor R72 and the resistor R73 .

9. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The sampling signal phase-sensitive detection module includes a single-channel single-pole double-throw analog switch U23, an operational amplifier U15B, an operational amplifier U25A, an operational amplifier U26, a resistor R85, a resistor R88, a resistor R89, a resistor R106, a resistor R109, a resistor R118, a resistor R120, a resistor R121, a resistor R122, a resistor R123, a capacitor C52 and a capacitor C55; Pin 5 of the operational amplifier U15B is connected to the sampling signal bandpass filter module, and pins 6 and 7 are connected to resistor R106 and pin 2 of the single-channel single-pole double-throw analog switch U23; Pin 1 of the operational amplifier U25A is connected to resistor R85 and pin 8 of the single-channel single-pole double-throw analog switch U23, and pin 2 is connected to resistor R85 and resistor R106; Pin 1 of the single-channel single-pole double-throw analog switch U23 is connected to resistor R109, and pin 6 is connected to the MCU module; Pin 1 of the operational amplifier U26 is connected to resistor R120 and resistor R122, pin 2 is connected to resistor R118 and capacitor C55, pin 4 is connected to resistor R121 and resistor R122, pin 5 is connected to resistor R88 and resistor R89, pin 6 is grounded, pin 7 is connected to resistor R123, and pin 8 is connected to resistor R89 ​​and resistor R109; capacitor C55 is connected to resistor R120 and grounded; One end of the capacitor C52 is connected to the resistor R88 and the ADC module, and the other end is connected to the resistor R121 and the ADC module.

10. A lithium battery AC internal resistance detection system as claimed in claim 1, Features: The sampling signal self-calibration module includes an operational amplifier U14, an operational amplifier U15A, an operational amplifier U16, a resistor R46, a resistor R55, a resistor R56, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R67, a resistor R68, a resistor R69, a resistor R71, a resistor R78, a resistor R79, a resistor R80, a capacitor C33, a capacitor C36, a capacitor C37 and a capacitor C49; Pin 1 of the operational amplifier U14 is connected to resistor R58 and resistor R60, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C36 is connected to resistor R58 and grounded; one end of the capacitor C33 is connected to resistor R46 and the ADC module, and the other end is connected to resistor R59 and the ADC module; Pin 1 of the operational amplifier U16 is connected to resistor R71 and resistor R79, pin 2 is connected to resistor R69 and capacitor C49, pin 4 is connected to resistor R78 and resistor R79, pin 5 is connected to resistor R63 and resistor R64, pin 6 is grounded, pin 7 is connected to resistor R80, and pin 8 is connected to resistor R64 and resistor R67; capacitor C49 is connected to resistor R71 and grounded; one end of the capacitor C37 is connected to resistor R63 and the ADC module, and the other end is connected to resistor R78 and the ADC module; One end of the resistor R62 is connected to the resistor R56, and the other end is grounded; pins 1 and 2 of the operational amplifier U15A are connected to the resistor R67, and pin 3 is connected to the resistor R65 and the resistor R68; the resistor R65 is connected to the DAC module; The sampling signal full-wave rectification module includes an operational amplifier U25B, an operational amplifier U28, an operational amplifier U29A, a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128, a resistor R129, a resistor R130, a resistor R131, a resistor R132, a resistor R133, a resistor R134, a resistor R135, a resistor R136, a resistor R137, a resistor R138, a resistor R139, a resistor R140, a capacitor C64 and a capacitor C67; Pin 1 of the operational amplifier U28 is connected to resistor R133 and resistor R136, pin 2 is connected to resistor R57 and capacitor C36, pin 4 is connected to resistor R59 and resistor R60, pin 5 is connected to resistor R46 and resistor R55, pin 6 is grounded, pin 7 is connected to resistor R61, and pin 8 is connected to resistor R55 and resistor R56; capacitor C67 is connected to resistor R133 and grounded; one end of capacitor C64 is connected to resistor R127 and ADC module, and the other end is connected to resistor R135 and ADC module; Pin 5 of the operational amplifier U25B is connected to resistor R138, pin 6 is connected to resistor R124, resistor R125 and resistor R126, and pin 7 is connected to resistor R125, resistor R132 and resistor R130; pin 1 of the operational amplifier U29A is connected to resistor R129, resistor R138 and resistor R139, pin 2 is connected to resistor R129, and pin 3 is connected to resistor R134 and resistor R140; the resistor R134 is connected to resistor R124 and a sampling signal bandpass filter module.

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