A voltage calibration device for lithium battery testing equipment

Abstract

This invention provides a voltage calibration device for lithium battery testing equipment in the field of lithium battery testing technology. It includes a pre-stage power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive / negative value switching module, a first-stage and second-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module. These modules are connected sequentially. The advantage of this invention is that it significantly improves the voltage calibration quality of lithium battery testing equipment.

Description

Technical Field

[0001] This invention relates to the field of lithium battery testing technology, and in particular to a voltage calibration device for lithium battery testing equipment. Background Technology

[0002] With the rapid development of lithium battery technology, the accuracy requirements for lithium battery testing equipment are also increasing rapidly. Stability requirements under different conditions and environments are also evolving towards higher standards. To adapt to this rapid development, the stability and functionality of lithium battery testing equipment are constantly being enhanced and updated. Correspondingly, the overall design complexity and precision of lithium battery testing equipment also need to be improved. In this context, calibration of the lithium battery testing equipment is necessary to improve the reliability of its voltage sampling accuracy.

[0003] During the calibration of lithium battery testing equipment, a highly stable voltage calibration source is required to ensure that the lithium battery testing equipment meets the design specifications after calibration, and to avoid the voltage sampling accuracy after calibration deviating from the design specifications due to unstable voltage output of the calibrated object.

[0004] Traditional voltage calibration sources use the switching power supply module of the system integration unit. This power supply module has problems such as high ripple noise, inability to adjust the output voltage to a very low level, and inability to guarantee high stability output even when the output voltage is very low. In other words, when this power supply module is used for calibration, the sampling system of the lithium battery test equipment will cause fluctuations in the sampled value due to the ripple noise of the test object. The calibration personnel cannot locate the current sampled value, which makes it impossible to calibrate the lithium battery test equipment to an optimal accuracy level during the calibration process.

[0005] Therefore, how to provide a voltage calibration device for lithium battery testing equipment to improve the voltage calibration quality of lithium battery testing equipment has become an urgent technical problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a voltage calibration device for lithium battery testing equipment, thereby improving the voltage calibration quality of lithium battery testing equipment.

[0007] The present invention is implemented as follows: a voltage calibration device for lithium battery testing equipment, comprising a front-end power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive and negative value switching module, a first-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module.

[0008] The pre-stage power supply and protection module, the isolated regulated power supply output module, the low-noise voltage reference source signal conditioning module, the first-stage voltage output amplitude control module, the voltage output positive and negative value switching module, the second-stage voltage output amplitude control module, and the third-stage voltage output amplitude control module are connected in sequence.

[0009] Furthermore, the pre-amplifier power supply and protection module includes a terminal block J1, a terminal block J2, a fuse F1, a diode D3, a diode D4, a diode D14, a light-emitting diode D5, a light-emitting diode D6, a light-emitting diode D7, a light-emitting diode D15, a Zener diode D2, a Zener diode D8, a Zener diode D9, a Zener diode D13, a MOSFET Q2, a MOSFET Q3, and a MOSFET... Q4, a MOSFET Q5, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R68, a resistor R69, a resistor R70, a resistor R71, a resistor R72, a resistor R73, a resistor R74, a resistor R75, a resistor R76, a capacitor C39, a capacitor C40, a capacitor C41, a capacitor C42, a buzzer B1, and an operational amplifier U5A;

[0010] The input terminal of diode D3 is connected to fuse F1, and the output terminal is connected to resistors R76, R72, R74, R75, R64, the output terminal of Zener diode D8, resistors R66 and R65, capacitor C39, and the drain of MOSFET Q2.

[0011] The Zener diode D13 is connected in parallel with capacitor C41, with its input terminal grounded and its output terminal connected to resistor R72 and pin 8 of operational amplifier U5A; the input terminal of LED D15 is connected to resistor R76 and its output terminal is connected to pin 1 of operational amplifier U5A; the diode D14 is connected in parallel with capacitor C42, with its input terminal connected to resistor R75 and pin 3 of operational amplifier U5A, and its output terminal grounded; pin 2 of operational amplifier U5A is connected to resistors R73 and R74.

[0012] The drain (D) of MOSFET Q4 is connected to the output terminal of LED D7. The source (S) of MOSFET Q4 is connected to capacitor C40, resistor R70, the input terminal of Zener diode D9, the source (S) of MOSFET Q3, resistor R71, the source (S) of MOSFET Q5, resistor R68, and the isolated regulated power supply output module, and is grounded. The gate (G) of MOSFET Q4 is connected to capacitor C40, resistor R70, resistor R69, the output terminal of Zener diode D9, and the gate (G) of MOSFET Q3. The input terminal of LED D7 is connected to resistor R64. The input terminal of Zener diode D8 is connected to resistor R69. The drain (D) of MOSFET Q3 is connected to resistors R66 and R71, and the gate (G) of MOSFET Q5. One end of resistor R67 is connected to the drain (D) of MOSFET Q5, and the other end is connected to resistor R65, capacitor C39, and the gate (G) of MOSFET Q2. The input terminal of LED D6 is connected to the source (S) of MOSFET Q2 and the isolated regulated power supply output module, and its output terminal is connected to resistor R68.

[0013] Pin 1 of the buzzer B1 is connected to the output terminal of resistor R62 and Zener diode D2, and pin 2 is connected to the input terminal of Zener diode D2 and the output terminal of LED D5; one end of resistor R63 is connected to the output terminal of resistor R62 and diode D4, and the other end is connected to the input terminal of LED D5.

[0014] The terminal J1 is connected to the input terminal of Zener diode D13, resistor R73, output terminal of diode D14, pin 4 of operational amplifier U5A, input terminal of Zener diode D9, and input terminal of diode D4, respectively; the terminal J2 is connected to the fuse F1 and pin 2 of buzzer B1, respectively.

[0015] Furthermore, the isolated regulated power supply output module includes an isolated regulated power supply chip U1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, and a light-emitting diode D1.

[0016] Pins 1 and 2 of the isolated voltage regulator chip U1 are connected to the pre-amplifier power supply and protection module. Pin 3 is connected to capacitors C1 and C2, the input terminal of LED D1, resistors R1, R5, R9, and R13, and the low-noise voltage reference signal conditioning module. Pin 4 is connected to and grounded to capacitors C1, C2, C3, and C4, resistors R2, R3, R6, R7, R10, R11, R14, and R15. Pin 5 is connected to capacitors C3 and C4, resistors R17 and R18, R4, R8, R12, and R16, and the low-noise voltage reference signal conditioning module. The output terminal of LED D1 is connected to resistors R17 and R18.

[0017] The resistor R1 is connected to resistors R2, R5, R6, R9, R10, R13 and R14; the resistor R3 is connected to resistors R4, R7, R8, R11, R12, R15 and R16.

[0018] Furthermore, the low-noise voltage reference source signal conditioning module includes a power reference source chip U3, an operational amplifier U4A, a capacitor C8, a capacitor C9, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C15, a capacitor C16, a capacitor C43, a capacitor C44, a resistor R22, a resistor R24, a resistor R33, a resistor R77, and a resistor R78.

[0019] Pins 2 and 3 of the power reference chip U3 are connected to capacitor C11 and the isolated regulated power supply output module; pin 4 is connected to capacitor C11 and grounded; pin 6 is connected to capacitors C12 and C13 and resistor R77. One end of capacitor C44 is connected to resistors R77 and R78, and the other end is connected to pin 2 of operational amplifier U4A and resistor R33. Pin 1 of operational amplifier U4A is connected to resistor R33 and the first-stage voltage output amplitude control module; pin 3 is connected to resistor R78 and capacitor C43.

[0020] After capacitors C15 and C16 are connected in parallel, one end is connected to pin 4 of U4A and resistor R24, and the other end is grounded; after capacitors C8 and C9 are connected in parallel, one end is connected to pin 8 of U4A and resistor R22, and the other end is grounded; both resistors R22 and R24 are connected to the isolated regulated power supply output module.

[0021] Furthermore, the first-level voltage output amplitude control module includes a DIP switch SW1, a resistor R25, a resistor R26, a resistor R28, a resistor R29, a resistor R31, a resistor R34, a resistor R39, a resistor R43, a resistor R48, a resistor R52, a resistor R55, a resistor R58, a capacitor C14, a capacitor C17, a capacitor C19, a capacitor C20, a capacitor C23, a capacitor C29, a capacitor C32, and an operational amplifier U2B;

[0022] Pin 1 of the DIP switch SW1 is connected to resistor R25 and the low-noise voltage reference source signal conditioning module; pin 2 is connected to resistor R25, resistor R26 and capacitor C17; pin 3 is connected to resistor R26, resistor R34 and capacitor C19; pin 4 is connected to resistor R34, resistor R39 and capacitor C23; pin 5 is connected to resistor R43, resistor R48 and capacitor C29; pin 6 is connected to resistor R48, resistor R52 and capacitor C32; pin 7 is connected to resistor R52 and resistor R55; and pins 10, 11, 12, 13, 14, 15 and 16 are connected to capacitor C14 and pin 5 of operational amplifier U2B.

[0023] One end of resistor R58 is connected to resistor R55, and the other end is grounded; resistor R39 is connected to resistor R43; capacitor C17 is connected to capacitors C19, C23, C29, and C32 and is grounded.

[0024] After resistors R28 and R31 are connected in parallel, one end is connected to pin 6 of operational amplifier U2B, resistor R29 and capacitor C20, and the other end is grounded; pin 7 of operational amplifier U2B is connected to resistor R29, capacitor C20 and voltage output positive and negative value switching module.

[0025] Furthermore, the voltage output positive / negative value switching module includes a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C10, a resistor R19, a resistor R20, a resistor R21, a resistor R35, a resistor R37, a resistor R42, a resistor R44, a resistor R46, a resistor R49, an operational amplifier U2A, a relay K1, a diode D1, a light-emitting diode D12, and a MOSFET Q1;

[0026] After capacitors C5 and C6 are connected in parallel, one end is connected to resistor R19 and pin 8 of operational amplifier U2A, and the other end is grounded; after capacitors C7 and C10 are connected in parallel, one end is connected to resistor R21 and pin 4 of operational amplifier U2A, and the other end is grounded; one end of resistor R20 is connected to pin 7 of relay K1 and the first-stage voltage output amplitude control module, and the other end is connected to resistor R23 and pin 2 of operational amplifier U2A; pin 1 of operational amplifier U2A is connected to resistor R23 and pin 5 of relay K1.

[0027] The gate (G) of the MOSFET Q1 is connected to resistors R24 and R44, the source (S) is connected to resistor R44, and the drain (D) is connected to pin 8 of relay K1, the input terminal of diode D1, resistors R46 and R49. The input terminal of the LED D12 is connected to resistors R35 and R37, and the output terminal is connected to resistors R46 and R49. Pin 1 of relay K1 is connected to resistors R35 and R37 and the output terminal of diode D1, and pin 3 is connected to the secondary voltage output amplitude control module.

[0028] Furthermore, the secondary voltage output amplitude control module includes a DIP switch SW2, a resistor R27, a resistor R30, a resistor R36, a resistor R40, a resistor R45, a resistor R50, a resistor R53, a resistor R56, a resistor R59, a resistor R60, a capacitor C18, a capacitor C21, a capacitor C25, a capacitor C27, a capacitor C30, a capacitor C33, a capacitor C35, a capacitor C37, an operational amplifier U4B, and a TVS diode D10.

[0029] Pin 1 of the DIP switch SW2 is connected to resistor R30 and the voltage output positive / negative value switching module; pin 2 is connected to resistor R30, resistor R36 and capacitor C21; pin 3 is connected to resistor R36, resistor R40 and capacitor C25; pin 4 is connected to resistor R40, resistor R45 and capacitor C27; pin 5 is connected to resistor R45, resistor R50 and capacitor C30; pin 6 is connected to resistor R50, resistor R53 and capacitor C33; pin 7 is connected to resistor R53, resistor R56 and capacitor C35; pin 7 is connected to resistor R56, resistor R59, resistor R60 and capacitor C37; pins 9, 10, 11, 12, 13, 14, 15, 16, capacitor C18, and pin 5 of operational amplifier U4B are connected.

[0030] The capacitor C21 is connected to and grounded with capacitors C25, C27, C30, C33, C35 and C37;

[0031] Pin 6 of the operational amplifier U4B is connected to resistor R27, the output terminal of TVS diode D10, and the three-stage voltage output amplitude control module, and pin 7 is connected to resistor R27.

[0032] Furthermore, the three-level voltage output amplitude control module includes a DIP switch SW3, a resistor R32, a resistor R38, a resistor R41, a resistor R47, a resistor R51, a resistor R54, a resistor R57, a resistor R61, a capacitor C22, a capacitor C24, a capacitor C26, a capacitor C28, a capacitor C31, a capacitor C34, a capacitor C36, and a capacitor C38.

[0033] Pin 1 of the DIP switch SW3 is connected to resistor R32 and the secondary voltage output amplitude control module; pin 2 is connected to resistor R32, resistor R38 and capacitor C22; pin 3 is connected to resistor R38, resistor R41 and capacitor C26; pin 4 is connected to resistor R41, resistor R47 and capacitor C28; pin 5 is connected to resistor R47, resistor R51 and capacitor C31; pin 6 is connected to resistor R51, resistor R54 and capacitor C34; pin 7 is connected to resistor R54, resistor R57 and capacitor C36; pin 8 is connected to resistor R57, resistor R61 and capacitor C38; and pins 9, 10, 11, 12, 13, 14, 15 and 16 are connected to capacitor C24.

[0034] The capacitor C22 is connected to and grounded with capacitors C26, C28, C31, C34, C36 and C38.

[0035] The advantages of this invention are:

[0036] 1. By setting up a pre-stage power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive / negative value switching module, a second-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module, and these modules are connected sequentially, through isolated voltage regulation... The power output module provides electrical isolation between the input and output. It outputs a low-noise voltage reference source to the first-level voltage output amplitude control module through a low-noise voltage reference source signal conditioning module. The voltage output amplitude is adjusted by the first-level, second-level, and third-level voltage output amplitude control modules, which enables the voltage calibration device to avoid interference from ripple noise. The output voltage can be adjusted to a very low level, and it can still provide a highly stable output even when the output voltage is very low. Ultimately, this greatly improves the voltage calibration quality of the lithium battery testing equipment.

[0037] 2. By setting up a buzzer B1 and LEDs D5, D6, D7 and D15 of different colors in the front-end power supply and protection module, the current access voltage status can be indicated, and the user can intuitively obtain the corresponding information.

[0038] 3. By adding an RC filter circuit consisting of resistors and capacitors to the power supply terminal of the op-amp, the ripple at the power supply terminal of the op-amp can be reduced.

[0039] 4. By using a DIP switch and a precision low-temperature drift voltage to select the output voltage, noise interference factors can be effectively avoided in the output signal.

[0040] 5. By adding a positive and negative output selection for the output voltage value to the voltage output positive and negative value switching module, users can more easily calibrate the positive and negative voltage values ​​without having to swap the wiring positions of the sampling points.

[0041] 6. Adding a combination circuit of DIP switch SW3 and voltage divider resistors to the three-stage voltage output amplitude control module can avoid the inability to output a voltage signal lower than the offset voltage for calibration due to the influence of the operational amplifier's offset voltage. Attached Figure Description

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Figure 1 This is a circuit block diagram of a voltage calibration device for lithium battery testing equipment according to the present invention.

[0044] Figure 2 This is a circuit diagram of the pre-stage power supply and protection module and the isolated regulated power supply output module of the present invention.

[0045] Figure 3 This is a circuit diagram of the low-noise voltage reference source signal conditioning module of the present invention.

[0046] Figure 4 This is a circuit diagram of the first-level voltage output amplitude control module and the voltage output positive and negative value switching module of the present invention.

[0047] Figure 5 This is a circuit diagram of the two-stage voltage output amplitude control module and the three-stage voltage output amplitude control module of the present invention. Detailed Implementation

[0048] The overall concept of the technical solution in this application embodiment is as follows: the input and output are electrically isolated by an isolated regulated power supply output module; a low-noise voltage reference source signal conditioning module outputs a low-noise voltage reference source to a first-level voltage output amplitude control module; and the voltage output amplitude is adjusted by a first-level voltage output amplitude control module, a second-level voltage output amplitude control module, and a third-level voltage output amplitude control module. This allows the voltage calibration device to avoid interference from ripple noise, and the output voltage can be adjusted to a very low level. It can ensure that a high degree of stability is provided even when the output voltage is very low, thereby improving the voltage calibration quality of the lithium battery testing equipment.

[0049] Please refer to Figures 1 to 5 As shown, a preferred embodiment of the voltage calibration device for lithium battery testing equipment of the present invention includes a front-end power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive and negative value switching module, a first-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module.

[0050] The pre-stage power supply and protection module is the first-stage power supply terminal of the voltage calibration device, and has voltage input protection function; the isolated regulated power supply output module is used to electrically isolate the input and output, and output an independent regulated voltage source; the low-noise voltage reference source signal conditioning module serves as the pre-stage output voltage of the voltage calibration source output adjustment section; the first-stage voltage output amplitude control module performs first-stage output amplitude switching control on the output voltage used for calibration; the voltage output positive and negative value switching module switches the voltage output value between positive and negative values ​​to accommodate the requirement of lithium battery testing equipment to calibrate positive and negative voltage values ​​separately; the second-stage voltage output amplitude control module performs second-stage output amplitude switching control on the output voltage used for calibration; and the third-stage voltage output amplitude control module performs third-stage output amplitude switching control on the output voltage used for calibration.

[0051] The pre-stage power supply and protection module, the isolated regulated power supply output module, the low-noise voltage reference source signal conditioning module, the first-stage voltage output amplitude control module, the voltage output positive and negative value switching module, the second-stage voltage output amplitude control module, and the third-stage voltage output amplitude control module are connected in sequence.

[0052] The pre-amplifier power supply and protection module includes a terminal block J1, a terminal block J2, a fuse F1, a diode D3, a diode D4, a diode D14, an LED D5, an LED D6, an LED D7, an LED D15, a Zener diode D2, a Zener diode D8, a Zener diode D9, a Zener diode D13, a MOSFET Q2, a MOSFET Q3, a MOSFET Q4, a MOSFET Q5, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R68, and a resistor R69. 9. Resistors R70, R71, R72, R73, R74, R75, and R76; capacitors C39, C40, C41, and C42; a buzzer B1; and an operational amplifier U5A. Terminals J1 and J2 are used to connect to a power supply to power the entire voltage calibration device, separating the voltage calibration source's power supply from the mains power supply. This reduces potential interference from the mains power supply under different environments, thereby reducing the impact of external factors on the stability of the output voltage. The operational amplifier U5A is preferably an LM393.

[0053] The input terminal of diode D3 is connected to fuse F1, and the output terminal is connected to resistors R76, R72, R74, R75, R64, the output terminal of Zener diode D8, resistors R66 and R65, capacitor C39, and the drain of MOSFET Q2.

[0054] The Zener diode D13 is connected in parallel with capacitor C41, with its input terminal grounded and its output terminal connected to resistor R72 and pin 8 of operational amplifier U5A; the input terminal of LED D15 is connected to resistor R76 and its output terminal is connected to pin 1 of operational amplifier U5A; the diode D14 is connected in parallel with capacitor C42, with its input terminal connected to resistor R75 and pin 3 of operational amplifier U5A, and its output terminal grounded; pin 2 of operational amplifier U5A is connected to resistors R73 and R74.

[0055] The drain (D) of MOSFET Q4 is connected to the output terminal of LED D7. The source (S) of MOSFET Q4 is connected to capacitor C40, resistor R70, the input terminal of Zener diode D9, the source (S) of MOSFET Q3, resistor R71, the source (S) of MOSFET Q5, resistor R68, and the isolated regulated power supply output module, and is grounded. The gate (G) of MOSFET Q4 is connected to capacitor C40, resistor R70, resistor R69, the output terminal of Zener diode D9, and the gate (G) of MOSFET Q3. The input terminal of LED D7 is connected to resistor R64. The input terminal of Zener diode D8 is connected to resistor R69. The drain (D) of MOSFET Q3 is connected to resistors R66 and R71, and the gate (G) of MOSFET Q5. One end of resistor R67 is connected to the drain (D) of MOSFET Q5, and the other end is connected to resistor R65, capacitor C39, and the gate (G) of MOSFET Q2. The input terminal of LED D6 is connected to the source (S) of MOSFET Q2 and the isolated regulated power supply output module, and its output terminal is connected to resistor R68.

[0056] Pin 1 of the buzzer B1 is connected to the output terminal of resistor R62 and Zener diode D2, and pin 2 is connected to the input terminal of Zener diode D2 and the output terminal of LED D5; one end of resistor R63 is connected to the output terminal of resistor R62 and diode D4, and the other end is connected to the input terminal of LED D5.

[0057] The terminal J1 is connected to the input terminal of Zener diode D13, resistor R73, output terminal of diode D14, pin 4 of operational amplifier U5A, input terminal of Zener diode D9, and input terminal of diode D4, respectively; the terminal J2 is connected to the fuse F1 and pin 2 of buzzer B1, respectively.

[0058] The isolated voltage regulator output module includes an isolated voltage regulator chip U1, capacitors C1, C2, C3, and C4, resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, and R18, and a light-emitting diode D1; the isolated voltage regulator chip U1 is preferably of model HVR6-24D15F100.

[0059] Pins 1 and 2 of the isolated voltage regulator chip U1 are connected to the pre-amplifier power supply and protection module. Pin 3 is connected to capacitors C1 and C2, the input terminal of LED D1, resistors R1, R5, R9, and R13, and the low-noise voltage reference signal conditioning module. Pin 4 is connected to and grounded to capacitors C1, C2, C3, and C4, resistors R2, R3, R6, R7, R10, R11, R14, and R15. Pin 5 is connected to capacitors C3 and C4, resistors R17 and R18, R4, R8, R12, and R16, and the low-noise voltage reference signal conditioning module. The output terminal of LED D1 is connected to resistors R17 and R18.

[0060] The resistor R1 is connected to resistors R2, R5, R6, R9, R10, R13 and R14; the resistor R3 is connected to resistors R4, R7, R8, R11, R12, R15 and R16.

[0061] The low-noise voltage reference source signal conditioning module includes a power reference source chip U3, an operational amplifier U4A, capacitors C8, C9, C11, C12, C13, C15, C16, C43, C44, resistors R22, R24, R33, R77, and R78; the power reference source chip U3 is preferably an LTC6657; the operational amplifiers U2A, U2B, U4A, and U4B are all high-precision dual-channel operational amplifiers, preferably OPA2189.

[0062] Pins 2 and 3 of the power reference chip U3 are connected to capacitor C11 and the isolated regulated power supply output module; pin 4 is connected to capacitor C11 and grounded; pin 6 is connected to capacitors C12 and C13 and resistor R77. One end of capacitor C44 is connected to resistors R77 and R78, and the other end is connected to pin 2 of operational amplifier U4A and resistor R33. Pin 1 of operational amplifier U4A is connected to resistor R33 and the first-stage voltage output amplitude control module; pin 3 is connected to resistor R78 and capacitor C43.

[0063] After capacitors C15 and C16 are connected in parallel, one end is connected to pin 4 of U4A and resistor R24, and the other end is grounded; after capacitors C8 and C9 are connected in parallel, one end is connected to pin 8 of U4A and resistor R22, and the other end is grounded; both resistors R22 and R24 are connected to the isolated regulated power supply output module.

[0064] The first-level voltage output amplitude control module includes a DIP switch SW1, resistors R25, R26, R28, R29, R31, R34, R39, R43, R48, R52, R55, R58, capacitors C14, C17, C19, C20, C23, C29, C32, and an operational amplifier U2B.

[0065] Pin 1 of the DIP switch SW1 is connected to resistor R25 and the low-noise voltage reference source signal conditioning module; pin 2 is connected to resistor R25, resistor R26 and capacitor C17; pin 3 is connected to resistor R26, resistor R34 and capacitor C19; pin 4 is connected to resistor R34, resistor R39 and capacitor C23; pin 5 is connected to resistor R43, resistor R48 and capacitor C29; pin 6 is connected to resistor R48, resistor R52 and capacitor C32; pin 7 is connected to resistor R52 and resistor R55; and pins 10, 11, 12, 13, 14, 15 and 16 are connected to capacitor C14 and pin 5 of operational amplifier U2B.

[0066] One end of resistor R58 is connected to resistor R55, and the other end is grounded; resistor R39 is connected to resistor R43; capacitor C17 is connected to capacitors C19, C23, C29, and C32 and is grounded.

[0067] After resistors R28 and R31 are connected in parallel, one end is connected to pin 6 of operational amplifier U2B, resistor R29 and capacitor C20, and the other end is grounded; pin 7 of operational amplifier U2B is connected to resistor R29, capacitor C20 and voltage output positive and negative value switching module.

[0068] The voltage output positive and negative value switching module includes a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C10, a resistor R19, a resistor R20, a resistor R21, a resistor R35, a resistor R37, a resistor R42, a resistor R44, a resistor R46, a resistor R49, an operational amplifier U2A, a relay K1, a diode D1, a light-emitting diode D12, and a MOSFET Q1;

[0069] After capacitors C5 and C6 are connected in parallel, one end is connected to resistor R19 and pin 8 of operational amplifier U2A, and the other end is grounded; after capacitors C7 and C10 are connected in parallel, one end is connected to resistor R21 and pin 4 of operational amplifier U2A, and the other end is grounded; one end of resistor R20 is connected to pin 7 of relay K1 and the first-stage voltage output amplitude control module, and the other end is connected to resistor R23 and pin 2 of operational amplifier U2A; pin 1 of operational amplifier U2A is connected to resistor R23 and pin 5 of relay K1.

[0070] The gate (G) of the MOSFET Q1 is connected to resistors R24 and R44, the source (S) is connected to resistor R44, and the drain (D) is connected to pin 8 of relay K1, the input terminal of diode D1, resistors R46 and R49. The input terminal of the LED D12 is connected to resistors R35 and R37, and the output terminal is connected to resistors R46 and R49. Pin 1 of relay K1 is connected to resistors R35 and R37 and the output terminal of diode D1, and pin 3 is connected to the secondary voltage output amplitude control module.

[0071] The secondary voltage output amplitude control module includes a DIP switch SW2, resistors R27, R30, R36, R40, R45, R50, R53, R56, R59, R60, capacitors C18, C21, C25, C27, C30, C33, C35, C37, an operational amplifier U4B, and a TVS diode D10.

[0072] Pin 1 of the DIP switch SW2 is connected to resistor R30 and the voltage output positive / negative value switching module; pin 2 is connected to resistor R30, resistor R36 and capacitor C21; pin 3 is connected to resistor R36, resistor R40 and capacitor C25; pin 4 is connected to resistor R40, resistor R45 and capacitor C27; pin 5 is connected to resistor R45, resistor R50 and capacitor C30; pin 6 is connected to resistor R50, resistor R53 and capacitor C33; pin 7 is connected to resistor R53, resistor R56 and capacitor C35; pin 7 is connected to resistor R56, resistor R59, resistor R60 and capacitor C37; pins 9, 10, 11, 12, 13, 14, 15, 16, capacitor C18, and pin 5 of operational amplifier U4B are connected.

[0073] The capacitor C21 is connected to and grounded with capacitors C25, C27, C30, C33, C35 and C37;

[0074] Pin 6 of the operational amplifier U4B is connected to resistor R27, the output terminal of TVS diode D10, and the three-stage voltage output amplitude control module, and pin 7 is connected to resistor R27.

[0075] The three-level voltage output amplitude control module includes a DIP switch SW3, a resistor R32, a resistor R38, a resistor R41, a resistor R47, a resistor R51, a resistor R54, a resistor R57, a resistor R61, a capacitor C22, a capacitor C24, a capacitor C26, a capacitor C28, a capacitor C31, a capacitor C34, a capacitor C36, and a capacitor C38.

[0076] Pin 1 of the DIP switch SW3 is connected to resistor R32 and the secondary voltage output amplitude control module; pin 2 is connected to resistor R32, resistor R38 and capacitor C22; pin 3 is connected to resistor R38, resistor R41 and capacitor C26; pin 4 is connected to resistor R41, resistor R47 and capacitor C28; pin 5 is connected to resistor R47, resistor R51 and capacitor C31; pin 6 is connected to resistor R51, resistor R54 and capacitor C34; pin 7 is connected to resistor R54, resistor R57 and capacitor C36; pin 8 is connected to resistor R57, resistor R61 and capacitor C38; and pins 9, 10, 11, 12, 13, 14, 15 and 16 are connected to capacitor C24.

[0077] The capacitor C22 is connected to and grounded with capacitors C26, C28, C31, C34, C36 and C38.

[0078] Working principle of this invention:

[0079] ① When the positive and negative terminals of terminals J1 and J2 are reversed:

[0080] When the user connects the positive terminal of the lithium battery to terminal J1 and the negative terminal to terminal J2, diode D3 is reverse-biased to cut off the power supply to the subsequent stage. The subsequent circuit will not be damaged due to the reversed polarity of the power supply. At the same time, diode D4 is forward-biased, and LED D5 emits red light. Resistor R63 acts as a current-limiting resistor for LED D5, causing buzzer B1 to sound to inform the user that the positive and negative terminals are reversed. Resistor R62 acts as a current-limiting resistor for buzzer B1, and Zener diode D2 is used to protect the voltage across buzzer B1 from exceeding its limit value.

[0081] ② When the positive and negative terminals of terminals J1 and J2 are connected correctly, but the applied voltage is higher than the peak value of the input voltage in the isolated regulated power supply output module:

[0082] Diode D4 is reverse-biased and cut off. LED D5 and buzzer B1 are not working. Current flows through fuse F1 and diode D3. Because the input voltage is higher than the design voltage, Zener diode D8 is conducting. Current flows from the cathode to the anode of Zener diode D8, creating a potential difference across resistor R70. NPN MOSFETs Q3 and Q4 saturate and conduct under the gate-source potential difference VGS. At this time, the impedance between the drain and source of MOSFETs Q4 and Q3 becomes very low. Entering saturation conduction will cause LED D7 to emit yellow light, indicating that the current voltage exceeds the operating voltage range. When MOSFET Q3 enters saturation conduction, it will pull the VGS voltage of NPN MOSFET Q5 down to near 0, causing MOSFET Q5 to enter the cutoff state. Because MOSFET Q5 is in the cutoff state, the VGS voltage of PNP MOSFET Q2 is almost equal at this time, so MOSFET Q2 also enters the cutoff state. At this time, LED D6 and the isolation regulated power supply output module do not work.

[0083] ③ When the positive and negative terminals of terminals J1 and J2 are connected correctly, but the applied voltage is lower than the peak value of the input voltage in the isolated regulated power supply output module:

[0084] The operating power supply, through the power input terminal and the action of resistor R72 and Zener diode D13, forms a relatively stable and safe voltage to power operational amplifier U5A. The positive terminal comparator of operational amplifier U5A, through the action of resistor R75 and diode D14, forms a stable comparator point at the positive input terminal of operational amplifier U5A. The negative terminal of operational amplifier U5A, through the series combination of resistors R74 and R73, when the input voltage is lower than the system operating voltage, the voltage at the negative input pin of operational amplifier U5A is lower than that at the positive input pin. At this time, the open-drain structure of operational amplifier U5A pulls the voltage of the network POWER-L down to ground level. At this time, LED D15 emits red light to indicate that the current voltage is lower than the normal operating voltage of the system. At the same time, through the action of the network POWER-L, MOSFET Q5 is turned off, and the subsequent circuit does not enter the operating mode.

[0085] ④ When the positive and negative terminals of terminals J1 and J2 are connected correctly, and the supplied voltage meets the system's design input voltage range:

[0086] When MOSFET Q3 enters the cutoff state, the comparator voltage at the negative input terminal of op-amp U5A is higher than the comparator voltage at the positive input terminal, and the output terminal is in an open-drain state. At this time, MOSFET Q5 enters a saturation conduction state under the action of resistors R66 and R71. In this state, the voltage VGS across the gate and source of MOSFET Q2 will form a potential difference under the action of resistors R65 and R67, causing MOSFET Q2 to enter a saturation conduction state. The isolation regulator chip U1 enters the working state, and its pin 3 outputs a +15V voltage relative to pin 4, and its pin 5 outputs a -15V voltage relative to pin 4. Resistors R1 to R16 are dummy loads for the isolation regulator chip U1, and their function is to keep the output current of the isolation regulator chip U1 above the minimum design value, so as to avoid the internal working state switching caused by the isolation regulator chip U1 entering a light-load mode, which would affect the stability of the output voltage.

[0087] LED D1 emits green light, indicating that the system has entered the working state. In this state, the power reference chip U3 in the low noise voltage reference signal conditioning module outputs a stable output voltage with low noise and low temperature drift on pin 6. The power supply structure of operational amplifiers U4 and U2 adopts a first-stage filter formed by a resistor and a capacitor in series, and then inputs the corresponding voltage to the input terminal of the operational amplifier to further reduce the power supply ripple to the operational amplifier.

[0088] The output voltage of the power reference chip U3 is processed by a low-pass filter composed of operational amplifier U4A. The filtered voltage signal is then output through pin 1 of operational amplifier U4A to the first-stage voltage output amplitude control module. The use of DIP switch SW1 in the first-stage voltage output amplitude control module effectively avoids introducing noise interference into the entire signal chain. Resistors R25, R26, R34, R39, R43, R48, R52, R55, and R58 used in this module are all precision low-temperature drift resistors. Capacitors C14, C17, C19, C23, C29, and C32 are used as filter capacitors, which can further reduce the impact of ambient temperature on the stability of the output voltage. After the user selects the first-stage voltage output amplitude by controlling the DIP switch SW1, the signal is transmitted to the signal conditioning circuit of the operational amplifier U2B. Through the parameter design of resistors R28, R31, R29, and capacitor C20, the voltage signal selected by the DIP switch undergoes the first-stage gain processing. Resistors R28, R31, and R29 are also low-temperature drift resistors.

[0089] The signal processed by op-amp U2B is transmitted to the voltage output positive / negative value switching module through pin 7. The voltage output positive / negative value switching module uses a voltage inverting circuit composed of op-amp U2A, where resistors R20 and R23 are precision low-temperature drift resistors, and relay K1 switching control circuit. The control of relay K1 is controlled by the DIP switch position of the network number SW_CON in the first-stage voltage output amplitude control module. When the output signal is selected as a positive voltage signal, the corresponding bit of the DIP switch is not switched. At this time, SW_CON is not connected to AGND, and the internal switch of relay K1 is in the normally closed state. Pins 3, 6, 7, and 2 of relay K1 are connected together to transmit the corresponding positive voltage signal to the second-stage voltage output amplitude control module. When the output signal is selected as a negative voltage signal, the corresponding bit of the DIP switch is turned on. At this time, SW_CON will be connected to AGND, and pins 3, 6, 5, and 4 of relay K1 will be connected together. At this time, LED D12 emits green light to indicate the current positive or negative voltage output status to the user. The voltage signal selected at this time is pin 7 of op-amp U2B. After being processed by the inverting circuit designed by op-amp U2A, the negative voltage signal is output through pin 1 and transmitted to the secondary voltage output amplitude control module.

[0090] The secondary voltage output amplitude control module consists of a DIP switch SW2, precision low-temperature drift resistors R30, R36, R40, R45, R50, R53, R56, R59, and R60, their corresponding filter capacitors C18, C21, C25, C27, C30, C33, C35, and C37, and a voltage follower designed from operational amplifier U4B. The selected voltage signal is output from pin 7 of operational amplifier U4B through resistor R27. This design adds a TVS diode D10 to avoid the influence of static electricity that may be introduced during operation on operational amplifier U4B. The addition of a voltage follower can effectively avoid the influence of the voltage divider resistors in the preceding stage on the subsequent circuit. Users can control the amplitude of the secondary voltage output by controlling the DIP switch.

[0091] Because the operational amplifier has an offset voltage, a three-stage voltage output amplitude control module is added to allow further adjustment of the calibration voltage value below its corresponding offset voltage value. Users can select the appropriate calibration voltage signal through the DIP switch SW3. The resistors R32, R38, R41, R47, R51, R54, R57, and R61 used in the three-stage voltage output amplitude control module are all low-temperature drift resistors, and their resistance values ​​are designed to be relatively small compared to the input impedance of the lithium battery testing equipment. When testing voltages lower than the operational amplifier's offset voltage, the minimum sampling accuracy of the equipment will not be affected.

[0092] The signal output by the final voltage calibration device is transmitted to the lithium battery test equipment to be calibrated through terminals J3 and J4, and to the third-party voltage measuring instrument used for calibration and comparison through terminals J5 and J6.

[0093] In summary, the advantages of this invention are:

[0094] 1. By setting up a pre-stage power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive / negative value switching module, a second-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module, and these modules are connected sequentially, through isolated voltage regulation... The power output module provides electrical isolation between the input and output. It outputs a low-noise voltage reference source to the first-level voltage output amplitude control module through a low-noise voltage reference source signal conditioning module. The voltage output amplitude is adjusted by the first-level, second-level, and third-level voltage output amplitude control modules, which enables the voltage calibration device to avoid interference from ripple noise. The output voltage can be adjusted to a very low level, and it can still provide a highly stable output even when the output voltage is very low. Ultimately, this greatly improves the voltage calibration quality of the lithium battery testing equipment.

[0095] 2. By setting up a buzzer B1 and LEDs D5, D6, D7 and D15 of different colors in the front-end power supply and protection module, the current access voltage status can be indicated, and the user can intuitively obtain the corresponding information.

[0096] 3. By adding an RC filter circuit consisting of resistors and capacitors to the power supply terminal of the op-amp, the ripple at the power supply terminal of the op-amp can be reduced.

[0097] 4. By using a DIP switch and a precision low-temperature drift voltage to select the output voltage, noise interference factors can be effectively avoided in the output signal.

[0098] 5. By adding a positive and negative output selection for the output voltage value to the voltage output positive and negative value switching module, users can more easily calibrate the positive and negative voltage values ​​without having to swap the wiring positions of the sampling points.

[0099] 6. Adding a combination circuit of DIP switch SW3 and voltage divider resistors to the three-stage voltage output amplitude control module can avoid the inability to output a voltage signal lower than the offset voltage for calibration due to the influence of the operational amplifier's offset voltage.

[0100] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A voltage calibration device for lithium battery testing equipment, characterized in that: It includes a pre-amplifier power supply and protection module, an isolated regulated power supply output module, a low-noise voltage reference source signal conditioning module, a first-stage voltage output amplitude control module, a voltage output positive and negative value switching module, a first-stage and second-stage voltage output amplitude control module, and a third-stage voltage output amplitude control module. The pre-amplifier power supply and protection module, the isolated regulated power supply output module, the low-noise voltage reference source signal conditioning module, the first-stage voltage output amplitude control module, the voltage output positive and negative value switching module, the second-stage voltage output amplitude control module, and the third-stage voltage output amplitude control module are connected in sequence. The first-level voltage output amplitude control module includes a DIP switch SW1. Pin 1 of the DIP switch SW1 is connected to resistor R25 and the low-noise voltage reference source signal conditioning module. Pin 2 is connected to resistors R25 and R26 and capacitor C17. Pin 3 is connected to resistors R26 and R34 and capacitor C19. Pin 4 is connected to resistors R34 and R39 and capacitor C23. Pin 5 is connected to resistors R43 and R48 and capacitor C29. Pin 6 is connected to resistors R48 and R52 and capacitor C32. Pin 7 is connected to resistors R52 and R55. Pins 10, 11, 12, 13, 14, 15, and 16 are connected to capacitor C14 and pin 5 of operational amplifier U2B. One end of resistor R58 is connected to resistor R55, and the other end is grounded; resistor R39 is connected to resistor R43; capacitor C17 is connected to capacitors C19, C23, C29, and C32 and grounded. After resistors R28 and R31 are connected in parallel, one end is connected to pin 6 of op-amp U2B, resistor R29 and capacitor C20, and the other end is grounded; pin 7 of op-amp U2B is connected to resistor R29, capacitor C20 and voltage output positive and negative value switching module. The voltage output positive / negative value switching module includes a capacitor C5. Capacitors C5 and C6 are connected in parallel, with one end connected to resistor R19 and pin 8 of operational amplifier U2A, and the other end grounded. Capacitors C7 and C10 are connected in parallel, with one end connected to resistor R21 and pin 4 of operational amplifier U2A, and the other end grounded. One end of resistor R20 is connected to pin 7 of relay K1 and the first-stage voltage output amplitude control module, and the other end is connected to resistor R23 and pin 2 of operational amplifier U2A. Pin 1 of operational amplifier U2A is connected to resistor R23 and pin 5 of relay K1. The gate (G) of MOSFET Q1 is connected to resistors R24 and R44, the source (S) is connected to resistor R44, and the drain (D) is connected to pin 8 of relay K1, the input terminal of diode D1, resistors R46 and R49. The input terminal of LED D12 is connected to resistors R35 and R37, and the output terminal is connected to resistors R46 and R49. Pin 1 of relay K1 is connected to resistors R35 and R37 and the output terminal of diode D1, and pin 3 is connected to the secondary voltage output amplitude control module.

2. The voltage calibration device for lithium battery testing equipment as described in claim 1, characterized in that: The pre-amplifier power supply and protection module includes a terminal block J1, a terminal block J2, a fuse F1, a diode D3, a diode D4, a diode D14, an LED D5, an LED D6, an LED D7, an LED D15, a Zener diode D2, a Zener diode D8, a Zener diode D9, a Zener diode D13, a MOSFET Q2, a MOSFET Q3, a MOSFET Q4, a MOSFET Q5, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R68, a resistor R69, a resistor R70, a resistor R71, a resistor R72, a resistor R73, a resistor R74, a resistor R75, a resistor R76, a capacitor C39, a capacitor C40, a capacitor C41, a capacitor C42, a buzzer B1, and an operational amplifier U5A. The input terminal of diode D3 is connected to fuse F1, and the output terminal is connected to resistors R76, R72, R74, R75, R64, the output terminal of Zener diode D8, resistors R66 and R65, capacitor C39, and the drain of MOSFET Q2. The Zener diode D13 is connected in parallel with capacitor C41, with its input terminal grounded and its output terminal connected to resistor R72 and pin 8 of operational amplifier U5A; the input terminal of LED D15 is connected to resistor R76 and its output terminal is connected to pin 1 of operational amplifier U5A; the diode D14 is connected in parallel with capacitor C42, with its input terminal connected to resistor R75 and pin 3 of operational amplifier U5A, and its output terminal grounded; pin 2 of operational amplifier U5A is connected to resistors R73 and R74. The drain (D) of MOSFET Q4 is connected to the output terminal of LED D7. The source (S) of MOSFET Q4 is connected to capacitor C40, resistor R70, the input terminal of Zener diode D9, the source (S) of MOSFET Q3, resistor R71, the source (S) of MOSFET Q5, resistor R68, and the isolated regulated power supply output module, and is grounded. The gate (G) of MOSFET Q4 is connected to capacitor C40, resistor R70, resistor R69, the output terminal of Zener diode D9, and the gate (G) of MOSFET Q3. The input terminal of LED D7 is connected to resistor R64. The input terminal of Zener diode D8 is connected to resistor R69. The drain (D) of MOSFET Q3 is connected to resistors R66 and R71, and the gate (G) of MOSFET Q5. One end of resistor R67 is connected to the drain (D) of MOSFET Q5, and the other end is connected to resistor R65, capacitor C39, and the gate (G) of MOSFET Q2. The input terminal of LED D6 is connected to the source (S) of MOSFET Q2 and the isolated regulated power supply output module, and its output terminal is connected to resistor R68. Pin 1 of the buzzer B1 is connected to the output terminal of resistor R62 and Zener diode D2, and pin 2 is connected to the input terminal of Zener diode D2 and the output terminal of LED D5; one end of resistor R63 is connected to the output terminal of resistor R62 and diode D4, and the other end is connected to the input terminal of LED D5. The terminal J1 is connected to the input terminal of Zener diode D13, resistor R73, output terminal of diode D14, pin 4 of operational amplifier U5A, input terminal of Zener diode D9, and input terminal of diode D4, respectively; the terminal J2 is connected to the fuse F1 and pin 2 of buzzer B1, respectively.

3. The voltage calibration device for lithium battery testing equipment as described in claim 1, characterized in that: The isolated regulated power supply output module includes an isolated regulated power supply chip U1, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, and a light-emitting diode D1. Pins 1 and 2 of the isolated voltage regulator chip U1 are connected to the pre-amplifier power supply and protection module. Pin 3 is connected to capacitors C1 and C2, the input terminal of LED D1, resistors R1, R5, R9, and R13, and the low-noise voltage reference signal conditioning module. Pin 4 is connected to and grounded to capacitors C1, C2, C3, and C4, resistors R2, R3, R6, R7, R10, R11, R14, and R15. Pin 5 is connected to capacitors C3 and C4, resistors R17 and R18, R4, R8, R12, and R16, and the low-noise voltage reference signal conditioning module. The output terminal of LED D1 is connected to resistors R17 and R18. The resistor R1 is connected to resistors R2, R5, R6, R9, R10, R13 and R14; the resistor R3 is connected to resistors R4, R7, R8, R11, R12, R15 and R16.

4. The voltage calibration device for lithium battery testing equipment as described in claim 1, characterized in that: The low-noise voltage reference source signal conditioning module includes a power reference source chip U3, an operational amplifier U4A, a capacitor C8, a capacitor C9, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C15, a capacitor C16, a capacitor C43, a capacitor C44, a resistor R22, a resistor R24, a resistor R33, a resistor R77, and a resistor R78. Pins 2 and 3 of the power reference chip U3 are connected to capacitor C11 and the isolated regulated power supply output module; pin 4 is connected to capacitor C11 and grounded; pin 6 is connected to capacitors C12 and C13 and resistor R77. One end of capacitor C44 is connected to resistors R77 and R78, and the other end is connected to pin 2 of operational amplifier U4A and resistor R33. Pin 1 of operational amplifier U4A is connected to resistor R33 and the first-stage voltage output amplitude control module; pin 3 is connected to resistor R78 and capacitor C43. After capacitors C15 and C16 are connected in parallel, one end is connected to pin 4 of U4A and resistor R24, and the other end is grounded; after capacitors C8 and C9 are connected in parallel, one end is connected to pin 8 of U4A and resistor R22, and the other end is grounded; both resistors R22 and R24 are connected to the isolated regulated power supply output module.

5. The voltage calibration device for lithium battery testing equipment as described in claim 1, characterized in that: The secondary voltage output amplitude control module includes a DIP switch SW2, resistors R27, R30, R36, R40, R45, R50, R53, R56, R59, R60, capacitors C18, C21, C25, C27, C30, C33, C35, C37, an operational amplifier U4B, and a TVS diode D10. Pin 1 of the DIP switch SW2 is connected to resistor R30 and the voltage output positive / negative value switching module; pin 2 is connected to resistor R30, resistor R36 and capacitor C21; pin 3 is connected to resistor R36, resistor R40 and capacitor C25; pin 4 is connected to resistor R40, resistor R45 and capacitor C27; pin 5 is connected to resistor R45, resistor R50 and capacitor C30; pin 6 is connected to resistor R50, resistor R53 and capacitor C33; pin 7 is connected to resistor R53, resistor R56 and capacitor C35; pin 7 is connected to resistor R56, resistor R59, resistor R60 and capacitor C37; pins 9, 10, 11, 12, 13, 14, 15, 16, capacitor C18, and pin 5 of operational amplifier U4B are connected. The capacitor C21 is connected to and grounded with capacitors C25, C27, C30, C33, C35 and C37; Pin 6 of the operational amplifier U4B is connected to resistor R27, the output terminal of TVS diode D10, and the three-stage voltage output amplitude control module, and pin 7 is connected to resistor R27.

6. The voltage calibration device for lithium battery testing equipment as described in claim 1, characterized in that: The three-level voltage output amplitude control module includes a DIP switch SW3, a resistor R32, a resistor R38, a resistor R41, a resistor R47, a resistor R51, a resistor R54, a resistor R57, a resistor R61, a capacitor C22, a capacitor C24, a capacitor C26, a capacitor C28, a capacitor C31, a capacitor C34, a capacitor C36, and a capacitor C38. Pin 1 of the DIP switch SW3 is connected to resistor R32 and the secondary voltage output amplitude control module; pin 2 is connected to resistor R32, resistor R38 and capacitor C22; pin 3 is connected to resistor R38, resistor R41 and capacitor C26; pin 4 is connected to resistor R41, resistor R47 and capacitor C28; pin 5 is connected to resistor R47, resistor R51 and capacitor C31; pin 6 is connected to resistor R51, resistor R54 and capacitor C34; pin 7 is connected to resistor R54, resistor R57 and capacitor C36; pin 8 is connected to resistor R57, resistor R61 and capacitor C38; and pins 9, 10, 11, 12, 13, 14, 15 and 16 are connected to capacitor C24. The capacitor C22 is connected to and grounded with capacitors C26, C28, C31, C34, C36 and C38.

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