Synchronous detection sampling circuit and method for phase compensation

Abstract

The invention belongs to the field of battery detection, and discloses a synchronous detection sampling circuit and method for phase compensation, and the circuit comprises a sampling amplification circuit, an RC phase modulation circuit, a signal amplification circuit, an analog switch and low-pass filter circuit, a temperature monitoring signal transmitting circuit, an operational circuit, and an analog-to-digital conversion circuit. The analog switch and low-pass filter circuit is connected with the operational circuit, the signal amplification circuit and the RC phase modulation circuit, the signal amplification circuit is connected with the sampling amplification circuit, and the operational circuit is connected with the temperature monitoring signal transmitting circuit and the analog-to-digital conversion circuit. According to the invention, the process of processing the to-be-tested signal by the tester in a synchronous detection mode is optimized, and the convenience and reliability of testing and debugging are improved.

Description

Technical Field

[0001] The present invention relates to the field of battery detection, and in particular to a synchronous detection sampling circuit and method for phase compensation. Background Art

[0002] Due to the internal structure and chemical characteristics of lithium batteries, their ohmic internal resistance can only be accurately obtained under the test of 1KHZ signal, so the synchronous detection technology for 1KHZ signal is applied by technicians. In synchronous detection, the phase relationship between the reference signal and the signal to be measured is the core factor that determines the demodulation performance. At present, the RC (RC refers to a circuit composed of resistors and capacitors) phase modulation circuit built with a mechanical potentiometer is mostly used to adjust the phase of the reference signal.

[0003] The RC phase modulation circuit constructed with a mechanical potentiometer needs to manually open the instrument chassis to adjust the phase of the reference signal, which makes each phase adjustment more cumbersome and unable to compensate for the real-time phase offset in time, resulting in an offset in the test results.

[0004] Therefore, how to provide a synchronous detection sampling circuit and method for phase compensation is a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiment of the present invention provides a synchronous detection sampling circuit and method for phase compensation, so as to solve the problem in the prior art that the real-time phase offset cannot be compensated in time, resulting in an offset in the test result.

[0006] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not a general review, nor is it intended to identify key / important components or to describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a synchronous detection sampling circuit for phase compensation is provided.

[0008] In one embodiment, a synchronous detection sampling circuit for phase compensation includes: The sampling and amplification circuit collects and amplifies the voltage signals formed by the positive and negative electrodes of the lithium battery; The RC phase modulation circuit collects phase information from the constant current source, outputs a reference signal for synchronous detection, and adjusts the phase of the reference signal according to the resistance value of the digital potentiometer; The signal amplifying circuit performs in-phase amplification processing on the output signal of the sampling amplifying circuit and performs in-phase processing on the signal of the in-phase amplifying circuit; The analog switch and low-pass filter circuit uses the reference signal output by the RC phase modulation circuit as the switch quantity to control the positive and negative phase outputs of the signal amplifier circuit; and attenuates the high-order harmonics in the synchronous detection; The temperature monitoring signal transmitting circuit inputs the reference voltage into the operation circuit; The operation circuit amplifies the low-pass filter output signal and the circuit temperature monitoring signal respectively, and suppresses common-mode interference by differential output; The analog-to-digital conversion circuit converts the analog signal output by the operation circuit into a digital signal; The analog switch is connected to the low-pass filter circuit, the operation circuit, the signal amplification circuit and the RC phase modulation circuit; the signal amplification circuit is connected to the sampling amplification circuit; the operation circuit is connected to the temperature monitoring signal transmission circuit and the analog-to-digital conversion circuit.

[0009] In one embodiment, the RC phase modulation circuit includes an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U3B, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2 and a digital potentiometer U2; The third terminal of the operational amplifier U1A is connected to one end of the resistor R1, the first terminal of the operational amplifier U1A is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to one end of the capacitor C1, one end of the resistor R6, one end of the resistor R7 and the fifth terminal of the operational amplifier U1B in sequence; The seventh end of the operational amplifier U1B is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the resistor R4 and the seventh and eighth ends of the digital potentiometer U2 in sequence, the other end of the resistor R4 is connected to one end of the capacitor C2 and the first end of the digital potentiometer U2 in sequence, the other end of the capacitor C2 is connected to the sixth end of the operational amplifier U3B and one end of the resistor R5 in sequence, and the seventh end of the operational amplifier U3B is connected to the other end of the resistor R5 and the second end of the operational amplifier U4A in sequence.

[0010] In one embodiment, the operational amplifier U1A, the operational amplifier U1B, the resistor R1, the resistor R2, the resistor R6, the resistor R7 and the capacitor C1 constitute a first-stage circuit to perform low-pass filtering on the sampled signal; The digital potentiometer U2, the resistor R3, the resistor R4 and the capacitor C2 form a phase adjustment circuit, and are combined with the operational amplifier U3B, the resistor R5 and the operational amplifier U4A to adjust the phase of the reference signal.

[0011] In one embodiment, the sampling and amplifying circuit includes capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, capacitor C8, resistor R20, resistor R21, resistor R22 and operational amplifier U8; Wherein, capacitor C3 is connected in parallel with capacitor C4, capacitor C5, capacitor C6 and capacitor C7, and connected to one end of resistor R20; The other end of resistor R20 is connected to one end of resistor R21 and the second end of operational amplifier U8 in sequence, the sixth end of operational amplifier U8 is connected to the other end of resistor R21, and the third end of operational amplifier U8 is connected to one end of resistor R22 and one end of capacitor C8 in sequence.

[0012] In one embodiment, the capacitor C8 and the resistor R22 form a high-pass filter circuit for filtering the sampled signal.

[0013] In one embodiment, the signal amplification circuit includes an operational amplifier U7A, an operational amplifier U7B, a resistor R16, a resistor R17, a resistor R18, and a resistor R19; Among them, the second end of the operational amplifier U7A is connected to one end of the resistor R19 and one end of the resistor R16 in sequence, the other end of the resistor R19 is connected to the first end of the operational amplifier U7A and one end of the resistor R17 in sequence, the other end of the resistor R17 is connected to the sixth end of the operational amplifier U7B and one end of the resistor R18 in sequence, and the other end of the resistor R18 is connected to the seventh end of the operational amplifier U7B.

[0014] In one embodiment, the signal amplification circuit includes a non-phase amplification part and an anti-phase amplification part, and the amplitudes of the non-phase signal and the anti-phase signal are equal.

[0015] In one embodiment, the operation circuit includes a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6A, and an operational amplifier U6B; Wherein, a first end of the operational amplifier U5A is connected to one end of the resistor R9 and one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R10, the other end of the resistor R10 is sequentially connected to one end of the resistor R11 and the first end of the operational amplifier U5B, the other end of the resistor R11 is connected to one end of the resistor R12, the other end of the resistor R12 is sequentially connected to the second end of the operational amplifier U5A and one end of the resistor R13, the other end of the resistor R13 is sequentially connected to the second end and the third end of the operational amplifier U6A, and the third end of the operational amplifier U5A is connected to the first end of the operational amplifier U6A; The second end of the operational amplifier U5B is connected to one end of the resistor R14 and one end of the resistor R15 in sequence, the other end of the resistor R14 is connected to the third end and the second end of the operational amplifier U6B in sequence, and the third end of the operational amplifier U5B is connected to the first end of the operational amplifier U6B.

[0016] In one embodiment, the analog switch and low-pass filter circuit includes an analog switch U11C, a resistor R26, a resistor R27, a capacitor C12, and a capacitor C13; The fourth end of the analog switch U11C is connected to one end of the resistor R26 , the other end of the resistor R26 is connected to one end of the capacitor C12 and one end of the resistor R27 , and the other end of the resistor R27 is connected to one end of the capacitor C13 .

[0017] According to a second aspect of an embodiment of the present invention, a synchronous detection sampling method for phase compensation is provided.

[0018] In one embodiment, the synchronous detection sampling method for phase compensation includes: A constant current source is used to output a constant current signal to form a voltage signal at the positive and negative electrodes of the lithium battery, and the voltage signal formed at the positive and negative electrodes of the lithium battery is collected and amplified by a sampling and amplification circuit; The output signal of the sampling amplifier circuit is amplified in phase, and the signal of the in-phase amplifier circuit is inverted; the phase information is collected from the constant current source through the RC phase modulation circuit, and the reference signal of the synchronous detection is output, and the phase of the reference signal is adjusted according to the resistance value of the digital potentiometer; The reference signal output by the RC phase modulation circuit is used as the switching quantity to control the positive and negative phase outputs of the signal amplifier circuit; the high-order harmonics in the synchronous detection are attenuated; The reference voltage is input into the operation circuit through the temperature monitoring signal transmitting circuit, and the low-pass filter output signal and the circuit temperature monitoring signal are amplified respectively, and the common mode interference is suppressed by differential output; the analog signal output by the operation circuit is converted into a digital quantity.

[0019] The technical solution provided by the embodiment of the present invention may have the following beneficial effects: (1) The present invention optimizes the tester's processing of the test signal using a synchronous detection method, thereby improving the convenience and reliability of test and debugging.

[0020] (2) The present invention uses a single-chip microcomputer to adjust the resistance value of a digital potentiometer to accurately compensate the phase of a 1KHZ reference signal in a small range. That is, the method of adjusting the resistance value of a digital potentiometer by a single-chip microcomputer is more convenient than the prior art, and has a higher compensation accuracy.

[0021] (3) The present invention uses a single-chip microcomputer to sample the temperature monitoring signal value change in real time to adjust the resistance of the digital potentiometer in real time, thereby achieving real-time compensation for the phase of the reference signal sampled by the synchronous detection. That is, real-time compensation for the real-time offset of the synchronous detection reference signal phase affected by temperature can be achieved.

[0022] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] Figure 1 is a diagram showing an implementation scheme of a synchronous detection sampling circuit for phase compensation according to an exemplary embodiment; Figure 2 is a diagram of an RC phase modulation circuit according to an exemplary embodiment; Figure 3 is a sampling and amplification circuit diagram according to an exemplary embodiment; Figure 4 is a signal amplification circuit diagram according to an exemplary embodiment; Figure 5 is a calculation circuit diagram according to an exemplary embodiment; Figure 6 is a temperature monitoring signal transmitting circuit diagram according to an exemplary embodiment; Figure 7 is a circuit diagram of an analog switch and a low-pass filter according to an exemplary embodiment; Figure 8 is an analog-to-digital conversion circuit diagram according to an exemplary embodiment; Fig. 9 is a principle block diagram of a synchronous detection sampling circuit for phase compensation according to an exemplary embodiment; Fig.10 The invention is a flow chart showing a synchronous detection sampling method for phase compensation according to an exemplary embodiment. DETAILED DESCRIPTION

[0025] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0026] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0027] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0028] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0029] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0030] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0031] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0032] Fig. 9 An embodiment of a synchronous detection sampling circuit for phase compensation of the present invention is shown.

[0033] In this optional embodiment, the synchronous detection sampling circuit for phase compensation includes: The sampling and amplifying circuit collects and amplifies the voltage signals formed by the positive and negative electrodes of the lithium battery.

[0034] The RC phase modulation circuit collects phase information from the constant current source, outputs a reference signal for synchronous detection, and adjusts the phase of the reference signal according to the resistance value of the digital potentiometer.

[0035] The signal amplifier circuit performs in-phase amplification processing on the output signal of the sampling amplifier circuit, and performs in-phase processing on the signal of the in-phase amplifier circuit.

[0036] The analog switch and low-pass filter circuit uses the reference signal output by the RC phase modulation circuit as the switch quantity to control the positive and negative phase outputs of the signal amplifier circuit; and attenuates the high-order harmonics in the synchronous detection.

[0037] The temperature monitoring signal transmitting circuit inputs the reference voltage into the operation circuit.

[0038] The operation circuit amplifies the low-pass filter output signal and the circuit temperature monitoring signal respectively, and suppresses common-mode interference by differential output.

[0039] The analog-to-digital conversion circuit converts the analog signal output by the operation circuit into a digital quantity.

[0040] The analog switch is connected to the low-pass filter circuit, the operation circuit, the signal amplification circuit and the RC phase modulation circuit; the signal amplification circuit is connected to the sampling amplification circuit; the operation circuit is connected to the temperature monitoring signal transmission circuit and the analog-to-digital conversion circuit.

[0041] In this optional embodiment, the RC phase modulation circuit includes an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U3B, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2 and a digital potentiometer U2; wherein the third end of the operational amplifier U1A is connected to one end of the resistor R1, the first end of the operational amplifier U1A is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to one end of the capacitor C1, one end of the resistor R6, and one end of the resistor R7 in sequence. The seventh end of the operational amplifier U1B is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the resistor R4 and the seventh and eighth ends of the digital potentiometer U2 in sequence, the other end of the resistor R4 is connected to one end of the capacitor C2 and the first end of the digital potentiometer U2 in sequence, the other end of the capacitor C2 is connected to the sixth end of the operational amplifier U3B and one end of the resistor R5 in sequence, and the seventh end of the operational amplifier U3B is connected to the other end of the resistor R5 and the second end of the operational amplifier U4A in sequence.

[0042] In this optional embodiment, operational amplifier U1A, operational amplifier U1B, resistor R1, resistor R2, resistor R6, resistor R7 and capacitor C1 constitute a first-stage circuit to perform low-pass filtering on the sampling signal; digital potentiometer U2, resistor R3, resistor R4 and capacitor C2 constitute a phase adjustment circuit, and in combination with operational amplifier U3B, resistor R5 and operational amplifier U4A, the reference signal is phase adjusted.

[0043] In this optional embodiment, the sampling and amplifying circuit includes capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, capacitor C8, resistor R20, resistor R21, resistor R22 and operational amplifier U8; wherein capacitor C3 is connected in parallel with capacitor C4, capacitor C5, capacitor C6 and capacitor C7, and is connected to one end of resistor R20; the other end of resistor R20 is connected to one end of resistor R21 and the second end of operational amplifier U8 in sequence, the sixth end of operational amplifier U8 is connected to the other end of resistor R21, and the third end of operational amplifier U8 is connected to one end of resistor R22 and one end of capacitor C8 in sequence.

[0044] In this optional embodiment, the capacitor C8 and the resistor R22 form a high-pass filter circuit for filtering the sampled signal.

[0045] In this optional embodiment, the signal amplification circuit includes an operational amplifier U7A, an operational amplifier U7B, a resistor R16, a resistor R17, a resistor R18 and a resistor R19; wherein the second end of the operational amplifier U7A is connected to one end of the resistor R19 and one end of the resistor R16 in sequence, the other end of the resistor R19 is connected to the first end of the operational amplifier U7A and one end of the resistor R17 in sequence, the other end of the resistor R17 is connected to the sixth end of the operational amplifier U7B and one end of the resistor R18 in sequence, and the other end of the resistor R18 is connected to the seventh end of the operational amplifier U7B.

[0046] In this optional embodiment, the signal amplification circuit includes an in-phase amplification part and an inverting amplification part, and the amplitudes of the in-phase signal and the inverting signal are equal.

[0047] In this optional embodiment, the operation circuit includes a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6A and an operational amplifier U6B; wherein a first end of the operational amplifier U5A is connected to one end of the resistor R9 and one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R10, the other end of the resistor R10 is sequentially connected to one end of the resistor R11 and the first end of the operational amplifier U5B, and the other end of the resistor R11 is sequentially connected to one end of the resistor R11 and the first end of the operational amplifier U5B. The second end of the operational amplifier U5B is connected to one end of the resistor R14 and one end of the resistor R15, the other end of the resistor R14 is connected to the third end and the second end of the operational amplifier U6B, and the third end of the operational amplifier U5B is connected to the first end of the operational amplifier U6B.

[0048] In this optional embodiment, the analog switch and low-pass filter circuit includes an analog switch U11C, a resistor R26, a resistor R27, a capacitor C12 and a capacitor C13; wherein the fourth end of the analog switch U11C is connected to one end of the resistor R26, the other end of the resistor R26 is connected to one end of the capacitor C12 and one end of the resistor R27, and the other end of the resistor R27 is connected to one end of the capacitor C13.

[0049] Fig.10 An embodiment of a synchronous detection sampling method for phase compensation of the present invention is shown.

[0050] In this optional embodiment, the synchronous detection sampling method for phase compensation includes: S101, using a constant current source to output a constant current signal, forming a voltage signal at the positive and negative electrodes of the lithium battery, and collecting and amplifying the voltage signal formed at the positive and negative electrodes of the lithium battery through a sampling and amplification circuit.

[0051] S102, amplify the output signal of the sampling amplifier circuit in phase, and perform inversion processing on the signal of the in-phase amplifier circuit; collect phase information from the constant current source through the RC phase modulation circuit, output the reference signal of the synchronous detection, and adjust the phase of the reference signal according to the resistance value of the digital potentiometer.

[0052] S103, using the reference signal output by the RC phase modulation circuit as the switching quantity to control the positive phase and negative phase outputs of the signal amplification circuit; and attenuating the high-order harmonics in the synchronous detection.

[0053] S104, input the reference voltage to the operation circuit through the temperature monitoring signal transmitting circuit, and amplify the low-pass filter output signal and the circuit temperature monitoring signal respectively, suppress the common mode interference through differential output; convert the analog signal output by the operation circuit into a digital quantity.

[0054] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are further described below from the perspective of architecture and principle, as follows: In synchronous detection, the phase relationship between the reference signal and the signal to be measured is the core factor that determines the demodulation performance. The present invention provides an efficient phase compensation method for synchronous detection sampling in the process of lithium battery internal resistance testing. The present invention uses a digital potentiometer to replace the original mechanical potentiometer, and cooperates with the circuit temperature detection circuit to realize the compensation of the real-time phase offset affected by temperature.

[0055] In the manufacturing process of lithium batteries, a 1KHZ AC signal is required as an excitation source to test the ohmic internal resistance of lithium batteries, so the corresponding tester will use a synchronous detection method to process the signal to be tested. The present invention optimizes this process and improves the convenience and reliability of test and debugging.

[0056] like Figure 1As shown, the 1KHZ constant current source forms a 1KHZ AC voltage on the lithium battery, which is amplified by the sampling amplifier circuit and then amplified in phase and inversely to obtain two signals with the same amplitude and a phase difference of 180°. At the same time, the RC phase modulation circuit collects the phase information of the original 1KHZ constant current source to form a reference signal (1KHZ square wave signal). In synchronous detection, the phase relationship between the reference signal and the signal to be measured is the core factor that determines the demodulation performance. The smaller the difference between the two, the more the demodulated signal can reflect the amplitude characteristics of the effective signal (1KHZ signal). Therefore, in the RC phase modulation circuit of the present invention, a digital potentiometer is connected in series with a capacitor, and the phase of the reference signal is adjusted by adjusting the resistance value of the digital potentiometer through a single-chip microcomputer to make the reference signal consistent with the phase of the signal to be measured.

[0057] The present invention uses a reference signal as a switch quantity at the analog switch to alternately conduct the in-phase signal to be tested and the inverse signal to be tested. Then, a low-pass filter circuit is used to implement synchronous detection sampling, and the amplitude information of the effective signal is converted into a DC quantity. Finally, the analog signal is converted into a digital signal through an operation circuit and an analog-to-digital conversion circuit, and sent to a single-chip microcomputer for processing.

[0058] The present invention also adds a temperature monitoring signal at the operation circuit, and the signal and the sampling signal alternately pass through the operation circuit, so the change of the signal amplitude can reflect the change of circuit temperature. The temperature compensation of the reference signal phase can be achieved through the calculation and adjustment of the single chip microcomputer.

[0059] The following is the calculation process of the microcontroller for the reference signal phase temperature compensation function: When the temperature is T1℃, the temperature monitoring signal is U1 after passing through the operation circuit, and the signal obtained by synchronous detection is U2. At this time, the corresponding digital potentiometer resistance is R0; when the temperature is T2℃, the temperature monitoring signal is U3 after passing through the operation circuit, and the signal obtained by synchronous detection is U4. At this time, the digital potentiometer resistance should be adjusted to R1, so that the signal obtained by synchronous detection changes from U4 to U2, to ensure that there is no deviation in the value of the same product under test after the temperature changes. Therefore, every time the amplitude of the temperature monitoring signal changes (U3-U1), the digital potentiometer resistance must be adjusted accordingly (R1-R0). That is, in order to minimize the impact of temperature on the signal obtained by synchronous detection, the microcontroller should follow The calculation method is to adjust the resistance value of the digital potentiometer ( is the real-time value of the temperature monitoring signal after passing through the calculation circuit).

[0060] Figure 1The diagram is an implementation scheme of the present invention. 1 is a 1KHZ constant current source, which outputs a 1KHZ constant current signal and forms a 1KHZ voltage signal at the positive and negative electrodes of the lithium battery; 2 is a sampling amplifier circuit, which collects and amplifies the 1KHZ voltage signal formed at the positive and negative electrodes of the lithium battery; 3 is an RC phase modulation circuit, which collects phase information from the 1KHZ constant current source and outputs a 1KHZ square wave with a duty cycle of 50% as a reference signal for synchronous detection. At the same time, the resistance value of the digital potentiometer inside the circuit can be adjusted by the single-chip microcomputer, thereby adjusting the phase of the reference signal; 4 is a common-phase amplifier circuit, which performs common-phase amplification on the output signal of the sampling amplifier circuit; 5 is an inverting amplifier circuit, which performs inverting on the signal of the common-phase amplifier circuit; 6 is a single-chip microcomputer, which performs phase modulation on the output signal of the sampling amplifier circuit; 7 is an analog switch, which uses the reference signal output by the RC phase modulation circuit as the switching quantity to control the alternating conduction of the in-phase amplifier circuit output and the inverting amplifier circuit output, thereby realizing synchronous detection of the 1KHZ effective signal in the sampling signal; 8 is a circuit temperature monitoring signal, which generates a stable reference voltage of 2V and inputs it into the operation circuit; 9 is a low-pass filter circuit, which attenuates the high-order harmonics in the synchronous detection; 10 is an operation circuit, which amplifies the low-pass filter output signal and the circuit temperature monitoring signal respectively, and suppresses common-mode interference by differential output; 11 is an analog-to-digital conversion circuit, which converts the analog signal output by the operation circuit into a digital quantity and sends it to the single-chip microcomputer.

[0061] Figure 2 This is the RC phase modulation circuit diagram. The operational amplifiers U1A and U1B (TL062CDT) and the resistors R1, R2, R6, R7, and the capacitor C1 form the first stage circuit, which performs low-pass filtering on the sampled signal and superimposes a 2.5V DC voltage on the sampled signal to facilitate subsequent signal processing.

[0062] Digital potentiometer U2 (MAX5402) and resistors R3, R4, and capacitor C2 form a phase adjustment circuit. Pins 1, 7, and 8 of digital potentiometer U2 (MAX5402) are equivalent to adjustable resistors, which are connected in parallel with resistor R4; pins 2 and 6 of digital potentiometer U2 (MAX5402) are connected to GND and 5V respectively to ensure the normal operation of the chip; pins 3, 4, and 5 of digital potentiometer U2 (MAX5402) are chip select, serial input, and clock pins, respectively, which are connected to the microcontroller to adjust the resistance. According to the phase angle formula , is the capacitive reactance of capacitor C2, which is (f is the frequency of the signal to be tested 1KHZ), is the capacitance value of capacitor C2; resistor R is the equivalent resistance of the circuit formed by resistors R3, R4 and digital potentiometer U2 (MAX5402), where digital potentiometer U2 (MAX5402) can be linearly adjusted in the range of 0-10KΩ through the control of the microcontroller, so 13KΩ≤R≤16.38KΩ; Substituting the value of resistance R into the phase angle formula, we can get 44.18°≤ ≤50.75°, that is, the reference signal phase angle can be accurately adjusted within the above range.

[0063] Finally, after the follow-up processing of the operational amplifier U3B (OPA2188AID) and the resistor R5, and then the rectification by the zero-crossing comparator operational amplifier U4A (LM2903), the phase-adjusted reference signal is obtained.

[0064] Figure 3 This is the sampling and amplification circuit diagram. Since the internal resistance of lithium batteries is generally at the mΩ level, the amplitude of the collected signal is very small and needs to be amplified. The capacitor C8 and the resistor R22 in the figure form a high-pass filter circuit with a cutoff frequency of , is the resistance value of resistor R22, is the capacitance value of capacitor C8, which has almost no attenuation effect on the 1KHZ sampling signal. According to the operational amplifier virtual short principle, the voltage of the in-phase terminal 3 pin of the operational amplifier U8 (OPA1611A) is the same as the voltage of the inverting terminal 2 pin of the operational amplifier; according to the operational amplifier virtual short principle, the current flowing through the resistor R20, the resistor R21 and the capacitors C3, C4, C5, C6, and C7 is the same. Therefore, it can be obtained that the measured signal obtained after the 1KHZ sampling signal passes through the sampling amplifier circuit is about 61 times the original signal.

[0065] Figure 4 The signal amplification circuit diagram is shown in Figure 2. According to the operational amplifier virtual short principle, the voltages of the inverting and non-inverting terminals of the operational amplifiers U7A and U7B (OPA2188AID) are equal, both 0V; according to the operational amplifier virtual short principle, the currents flowing through resistors R16, R17, R18, and R19 are equal; therefore, the inverting signal is amplified 4 times compared to the measured signal, but the phase deviation is 180°, and the non-inverting signal has the same amplitude as the inverting signal, but the phase deviation is 180°.

[0066] Figure 5It is the operation circuit diagram. Among them, U5A and U5B are operational amplifier chips (OPA2188AID), and U6A and U6B are operational amplifier chips (OPA2340UA). According to the virtual short principle of the operational amplifier, it can be known that the currents on the in-phase and inverting ends of the operational amplifiers U5A, U5B, U6A, and U6B can be approximately equivalent to 0, so it can be obtained that the currents flowing through R8 and R9 are equal, the currents flowing through R10 and R11 are equal, the currents flowing through R12 and R13 are equal, and the currents flowing through R14 and R15 are equal. According to the virtual short principle of the operational amplifier, it can be known that the potential of the in-phase and inverting ends of the operational amplifier U5A is the same, the potential of the in-phase and inverting ends of the operational amplifier U5B is the same, the potential of the in-phase and inverting ends of the operational amplifier U6A is the same, and the potential of the in-phase and inverting ends of the operational amplifier U6B is the same. According to the above two principles, the positive voltage of the differential input of the AD chip can be obtained , AD chip differential input negative voltage , represents the input voltage of the operational circuit, so the gain coefficient of the operational circuit is .

[0067] Figure 6 This is a temperature monitoring signal transmission circuit diagram, including voltage reference chip U9, capacitor C9, capacitor C10, capacitor C11, resistor R23, resistor R24, resistor R25 and op amp U10A. The 9V DC voltage input outputs a stable 7V DC voltage through the voltage reference chip U9 (ADR4550), and then divides the voltage through resistors R23 and R25 to obtain a stable 2V DC voltage, and then isolates the front and rear circuits through op amp U10A (OPA2188AID), and outputs a stable 2V DC temperature monitoring signal. Among them, capacitors C9, C10, and C11 play a role in stabilizing input and output.

[0068] Figure 7 The analog switch and low-pass filter circuit diagram is shown in Figure 1. The reference signal output by the RC phase modulation circuit is used as the switch quantity to control the analog switch U11C (MC14020B) to alternately conduct the in-phase amplification signal input pin and the inverting amplification input pin. The output is filtered twice by resistor R26, capacitor C12, resistor R27, and capacitor C13 to output the final modulated signal, which is also the input signal of the operation circuit. The cutoff frequencies of the two low-pass filters are (R is the resistance value in the low-pass filter circuit, and C is the capacitance value in the low-pass filter).

[0069] Figure 8 for Figure 1The analog-to-digital conversion circuit in the circuit includes a crystal oscillator U12, an analog-to-digital conversion chip U13, a capacitor C14, a resistor R28, an inductor L1, an inductor L2, and an inductor L3. The crystal oscillator U12, the resistor R28, and the capacitor C14 constitute a crystal oscillator circuit. The resistor R28 is used for current limiting, and the capacitor C14 is used to ensure the stability of the power supply and thus ensure that the crystal oscillator outputs a stable 8MHZ pulse, providing normal working pulses for the analog-to-digital conversion chip U13 (ADS1251). The 1st and 2nd pins of the analog-to-digital conversion chip U13 (ADS1251) are connected to the positive output and negative output of the operation circuit respectively; the 3rd, 4th, and 7th pins are connected to the 5V power supply, the crystal oscillator circuit output, and the ground GND respectively to ensure the normal operation of the chip; the 5th and 6th pins are connected to the single-chip microcomputer to receive the clock pulse of the single-chip microcomputer to transmit digital signals; the 8th pin is connected to the reference voltage 5V, which determines that the amplitude range of the analog signal in the analog-to-digital conversion is 0~5V.

[0070] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A synchronous detection sampling circuit for phase compensation, characterized in that: include: The sampling and amplification circuit collects and amplifies the voltage signals formed by the positive and negative electrodes of the lithium battery; The RC phase modulation circuit collects phase information from the constant current source, outputs a reference signal for synchronous detection, and adjusts the phase of the reference signal according to the resistance value of the digital potentiometer; The signal amplifying circuit performs in-phase amplification processing on the output signal of the sampling amplifying circuit and performs in-phase processing on the signal of the in-phase amplifying circuit; The analog switch and low-pass filter circuit uses the reference signal output by the RC phase modulation circuit as the switch quantity to control the positive and negative phase outputs of the signal amplifier circuit; and attenuates the high-order harmonics in the synchronous detection; The temperature monitoring signal transmitting circuit inputs the reference voltage into the operation circuit; The operation circuit amplifies the low-pass filter output signal and the circuit temperature monitoring signal respectively, and suppresses common-mode interference by differential output; The analog-to-digital conversion circuit converts the analog signal output by the operation circuit into a digital signal; The analog switch is connected to the low-pass filter circuit, the operation circuit, the signal amplification circuit and the RC phase modulation circuit; the signal amplification circuit is connected to the sampling amplification circuit; the operation circuit is connected to the temperature monitoring signal transmission circuit and the analog-to-digital conversion circuit.

2. A synchronous detection sampling circuit for phase compensation according to claim 1, characterized in that: The RC phase modulation circuit includes an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U3B, an operational amplifier U4A, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2 and a digital potentiometer U2; The third end of the operational amplifier U1A is connected to one end of the resistor R1, the first end of the operational amplifier U1A is connected to one end of the resistor R2, and the other end of the resistor R2 is sequentially connected to one end of the capacitor C1, one end of the resistor R6, one end of the resistor R7, and the fifth end of the operational amplifier U1B; The seventh end of the operational amplifier U1B is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the resistor R4 and the seventh and eighth ends of the digital potentiometer U2 in sequence, the other end of the resistor R4 is connected to one end of the capacitor C2 and the first end of the digital potentiometer U2 in sequence, the other end of the capacitor C2 is connected to the sixth end of the operational amplifier U3B and one end of the resistor R5 in sequence, and the seventh end of the operational amplifier U3B is connected to the other end of the resistor R5 and the second end of the operational amplifier U4A in sequence.

3. A synchronous detection sampling circuit for phase compensation according to claim 2, characterized in that: The operational amplifier U1A, the operational amplifier U1B, the resistor R1, the resistor R2, the resistor R6, the resistor R7 and the capacitor C1 constitute a first-stage circuit for performing low-pass filtering on the sampling signal; The digital potentiometer U2, the resistor R3, the resistor R4 and the capacitor C2 form a phase adjustment circuit, and in combination with the operational amplifier U3B, the resistor R5 and the operational amplifier U4A, the reference signal is phase adjusted.

4. A synchronous detection sampling circuit for phase compensation according to claim 1, characterized in that: The sampling and amplifying circuit includes capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, capacitor C8, resistor R20, resistor R21, resistor R22 and operational amplifier U8; The capacitor C3 is connected in parallel with the capacitor C4, the capacitor C5, the capacitor C6 and the capacitor C7, and is connected to one end of the resistor R20; The other end of the resistor R20 is connected to one end of the resistor R21 and the second end of the operational amplifier U8 in sequence, the sixth end of the operational amplifier U8 is connected to the other end of the resistor R21, and the third end of the operational amplifier U8 is connected to one end of the resistor R22 and one end of the capacitor C8 in sequence.

5. A synchronous detection sampling circuit for phase compensation according to claim 4, characterized in that: The capacitor C8 and the resistor R22 form a high-pass filter circuit for filtering the sampling signal.

6. A synchronous detection sampling circuit for phase compensation according to claim 1, characterized in that: The signal amplification circuit includes an operational amplifier U7A, an operational amplifier U7B, a resistor R16, a resistor R17, a resistor R18 and a resistor R19; Among them, the second end of the operational amplifier U7A is connected to one end of the resistor R19 and one end of the resistor R16 in sequence, the other end of the resistor R19 is connected to the first end of the operational amplifier U7A and one end of the resistor R17 in sequence, the other end of the resistor R17 is connected to the sixth end of the operational amplifier U7B and one end of the resistor R18 in sequence, and the other end of the resistor R18 is connected to the seventh end of the operational amplifier U7B.

7. A synchronous detection sampling circuit for phase compensation according to claim 6, characterized in that: The signal amplifying circuit comprises an in-phase amplifying part and an inverting amplifying part, and the amplitudes of the in-phase signal and the inverting signal are equal.

8. The synchronous detection sampling circuit for phase compensation according to claim 1, characterized in that: The operation circuit includes a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, an operational amplifier U5A, an operational amplifier U5B, an operational amplifier U6A and an operational amplifier U6B; Wherein, a first end of the operational amplifier U5A is connected to one end of the resistor R9 and one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R10, the other end of the resistor R10 is sequentially connected to one end of the resistor R11 and the first end of the operational amplifier U5B, the other end of the resistor R11 is connected to one end of the resistor R12, the other end of the resistor R12 is sequentially connected to the second end of the operational amplifier U5A and one end of the resistor R13, the other end of the resistor R13 is sequentially connected to the second end and the third end of the operational amplifier U6A, and the third end of the operational amplifier U5A is connected to the first end of the operational amplifier U6A; The second end of the operational amplifier U5B is connected to one end of the resistor R14 and one end of the resistor R15 in sequence, the other end of the resistor R14 is connected to the third end and the second end of the operational amplifier U6B in sequence, and the third end of the operational amplifier U5B is connected to the first end of the operational amplifier U6B.

9. The synchronous detection sampling circuit for phase compensation according to claim 1, characterized in that: The analog switch and low-pass filter circuit includes an analog switch U11C, a resistor R26, a resistor R27, a capacitor C12 and a capacitor C13; The fourth end of the analog switch U11C is connected to one end of the resistor R26, the other end of the resistor R26 is connected to one end of the capacitor C12 and one end of the resistor R27, and the other end of the resistor R27 is connected to one end of the capacitor C13.

10. A synchronous detection sampling method for phase compensation, characterized in that: include: A constant current source is used to output a constant current signal to form a voltage signal at the positive and negative electrodes of the lithium battery, and the voltage signal formed at the positive and negative electrodes of the lithium battery is collected and amplified by a sampling and amplification circuit; Perform in-phase amplification processing on the output signal of the sampling amplifier circuit, and perform in-phase processing on the signal of the in-phase amplifier circuit; Through the RC phase modulation circuit, the phase information is collected from the constant current source, and the reference signal of the synchronous detection is output, and the phase of the reference signal is adjusted according to the resistance value of the digital potentiometer; The reference signal output by the RC phase modulation circuit is used as the switching quantity to control the positive and negative phase outputs of the signal amplifier circuit; the high-order harmonics in the synchronous detection are attenuated; The reference voltage is input into the operation circuit through the temperature monitoring signal transmitting circuit, and the low-pass filter output signal and the circuit temperature monitoring signal are amplified respectively, and the common mode interference is suppressed by differential output; the analog signal output by the operation circuit is converted into a digital quantity.

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