A signal isolation transformer

Abstract

The utility model relates to a signal isolation converter, including signal sampling circuit, anti -interference circuit, amplifier circuit, isolation circuit and rectification output amplifier circuit that connect gradually, chopper circuit is connected with the isolation circuit, and one end of zero -setting full -scale circuit is connected with the input of amplifier circuit, and the other end of zero -setting full -scale circuit is connected between the output of amplifier circuit and the input of isolation circuit, signal sampling circuit is used for receiving input voltage or input current signal, and the first voltage signal is exported to anti -interference circuit, the second voltage signal that amplifier circuit receives anti -interference circuit exports, and after zero -setting full -scale circuit carries out compensation or correction to the second voltage signal, through amplifier circuit exports to isolation circuit, rectification output amplifier circuit receives the isolation voltage signal from the output of isolation circuit, and converts the isolation voltage signal into voltage or current signal output. Can convert the voltage / current of input into voltage / current signal output.

Description

Technical Field

[0001] This utility model relates to the field of converter technology, and in particular to a signal isolation converter. Background Technology

[0002] In modern industry and automation, signal converters play an indispensable role as key equipment. Their main function is to convert one type of signal into another for subsequent processing and application. Signal converters can convert between different voltage / current signals to meet the needs of various applications, and secondly, they can greatly reduce the complexity of transmitted signals and improve transmission efficiency.

[0003] The signal conversion process suffers from problems such as signal distortion and poor anti-interference capability (see CN202679251U, "A Signal Isolation Transmitter"). Its control power supply section is as follows: Figure 1 As shown, a push-pull circuit is used to supply power to the signal before and after the isolation signal. Simultaneously, the signal from the transformer section of the push-pull circuit is used to chop the input signal using the same oscillation circuit. Furthermore, the response time can theoretically be improved by controlling the switching frequency of transistors such as Q12 / Q13, theoretically achieving high-response transmission. However, it still has the following shortcomings: 1. It can only acquire voltage signals, and cannot transmit current signals, even common current signals such as 4-20mA, which limits its functionality; 2. At position U11A, there is no correction circuit for the input signal. When the normalized value of the output signal does not correspond to the input, there is no zero-value correction circuit or full-value correction circuit, making it difficult to guarantee the output accuracy of the signal. 3. For complex operating environments, there may be interference signals, and this circuit does not have a processing circuit for interference signals (such as common common-mode interference); 4. The output signal is only a voltage type output and cannot achieve current type signal output. Utility Model Content

[0004] The purpose of this utility model is to overcome the above-mentioned deficiencies in the prior art and provide a signal isolation converter, including a signal sampling circuit, an isolation circuit, a chopper circuit, a rectifier output amplifier circuit, and also including an anti-interference circuit, an amplifier circuit, and a zero-adjustment / full-scale adjustment circuit. The signal sampling circuit, the anti-interference circuit, the amplification circuit, the isolation circuit, and the rectified output amplification circuit are connected in sequence; the chopper circuit is connected to the isolation circuit; one end of the zero-adjustment and full-scale adjustment circuit is connected to the input terminal of the amplification circuit; and the other end of the zero-adjustment and full-scale adjustment circuit is connected between the output terminal of the amplification circuit and the input terminal of the isolation circuit. The signal sampling circuit is used to receive input voltage or input current signals from the input terminal and output a first voltage signal to the anti-interference circuit. The amplifier circuit receives the second voltage signal output by the anti-interference circuit. After the zero-adjustment and full-scale adjustment circuit compensates or corrects the second voltage signal, it outputs it to the isolation circuit through the output terminal of the amplifier circuit. The rectifier output amplifier circuit receives the isolation voltage signal output from the isolation circuit, and outputs the isolation voltage signal after converting it into a voltage or current signal.

[0005] This invention uses a signal sampling circuit to acquire current and voltage at different levels, thereby converting the input voltage / current signal into a voltage / current output signal. The signal conversion circuit, composed of the signal sampling circuit, anti-interference circuit, amplification circuit, zero-adjustment and full-scale adjustment circuit, chopper circuit, isolation circuit, and rectifier output amplification circuit, is driven at the same frequency as the power supply circuit, reducing the influence of the power supply circuit on the signal during switching, reducing the difficulty of the switching drive circuit, and isolating the power supply signal, input signal, and output signal.

[0006] Preferably, the signal sampling circuit includes a voltage divider sampling resistor R3, one end of which serves as the first signal input terminal of the signal sampling circuit, and the other end of which serves as the second signal input terminal of the signal sampling circuit. The second signal input terminal of the signal sampling circuit is grounded.

[0007] Preferably, the signal sampling circuit includes a voltage divider sampling resistor R1. One end of the voltage divider sampling resistor R1 serves as the first signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R1 serves as the first output terminal of the signal sampling circuit and is connected to the first input terminal of the anti-interference circuit. The other end of the voltage divider sampling resistor R1 is also connected to one end of a voltage divider sampling resistor R3. The non-grounded end of the grounding resistor R4 serves as the second signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R3 is connected to the grounded end of the grounding resistor R4. The grounded end of the grounding resistor R4 also serves as the second output terminal of the signal sampling circuit and is connected to the second input terminal of the anti-interference circuit.

[0008] The signal sampling circuit acquires current and voltage through the voltage divider sampling resistors in the sampling circuit, and realizes the conversion of the input signal. It can achieve, but is not limited to, the conversion of high voltage signals to low voltage signals, the conversion of current signals to voltage signals, and the sampling of small signals at the mV level.

[0009] Preferably, the anti-interference circuit is used to improve the common-mode rejection ratio and the signal-to-noise ratio of the input signal, and includes a resistor R2, a grounding resistor R5, a resistor R6, and an operational amplifier N1; one end of the resistor R2 and the grounding end of the grounding resistor R5 serve as the first input terminal and the second input terminal of the anti-interference circuit, respectively; the other end of the resistor R2 and the non-grounding end of the grounding resistor R5 are both connected to the operational amplifier N1; the resistor R6 is connected to two gain configuration pins of the operational amplifier N1 for configuring the input signal amplification factor; and the output terminal of the operational amplifier N1 serves as the output terminal of the anti-interference circuit.

[0010] Using an instrumentation operational amplifier as the first stage of the circuit can suppress common-mode interference on the input side, improve the signal-to-noise ratio, and enable the transmission of useful signals. This is more conducive to signal transmission and acquisition in complex working conditions. An overcurrent protection circuit is added to the output side to improve the reliability of the module.

[0011] Preferably, the amplification circuit is used to perform signal normalization processing and includes an operational amplifier N2A. The first input terminal of the operational amplifier N2A is connected to the output terminal of the anti-interference circuit, the second input terminal and the output terminal of the operational amplifier N2A are both connected to the zero-adjustment and full-scale adjustment circuit, and the output terminal of the operational amplifier N2A is also connected to the isolation circuit.

[0012] The amplifier circuit utilizes the characteristics of operational amplifiers to normalize input signals of different types and sizes, ensuring consistent utilization of the subsequent chopper circuit.

[0013] Preferably, the zero-adjustment and full-scale adjustment circuit includes a zero-adjustment sub-circuit and a full-scale adjustment sub-circuit. The zero-adjustment sub-circuit is connected to the second input terminal of the amplifier circuit and one end of the feedback resistor unit, respectively. The full-scale adjustment sub-circuit is connected to the other end of the feedback resistor unit and the output terminal of the amplifier circuit, respectively.

[0014] Preferably, it further includes an oscillation circuit, a symmetrical half-bridge circuit, and an isolation power supply circuit for powering the signal isolation converter, which are connected in sequence. The isolation power supply circuit is also connected to the anti-interference circuit, the amplification circuit, the zero-adjustment and full-scale adjustment circuit, and the output rectifier amplification circuit, respectively.

[0015] Preferably, the zero-adjustment and full-scale adjustment circuit includes a zero-adjustment sub-circuit and a full-scale adjustment sub-circuit. The zero-adjustment sub-circuit is connected to the second input terminal of the amplifier circuit and one end of the feedback resistor unit, respectively. The full-scale adjustment sub-circuit is connected to the other end of the feedback resistor unit and the output terminal of the amplifier circuit, respectively. The zero-adjustment sub-circuit includes potentiometer P2, the full-scale adjustment sub-circuit includes potentiometer P1, and the feedback resistor unit includes resistor R7. The first and second fixed terminals of the potentiometer P2 are both connected to the isolation power supply circuit, and the sliding terminal of the potentiometer P2 is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor R7, respectively. The first fixed terminal and the sliding terminal of the potentiometer P1 are both connected to the other end of the feedback resistor R7, and the second fixed terminal of the potentiometer P1 is connected to the output terminal of the operational amplifier N2A.

[0016] By using the zero-adjustment circuit for compensation, the minimum input value corresponds to the minimum output value. By using the full-scale adjustment circuit for correction, the maximum input value corresponds to the maximum output value. Through the correction of the zero-adjustment circuit and the full-scale adjustment circuit, higher accuracy and linearity are achieved.

[0017] Preferably, the rectifier output amplifier circuit includes a voltage output unit and a current output unit, which are used to output voltage signals and current signals, respectively.

[0018] Preferably, the voltage output unit includes an operational amplifier N3A. The first input terminal of the operational amplifier N3A is connected to the same-name terminal of the secondary winding of transformer T1 and the non-grounded terminal of grounding capacitor C1. The second input terminal of the operational amplifier N3A is connected to one end of resistor R11. The other end of resistor R11 is connected to the non-grounded terminal of grounding resistor R10 and the current output unit. The opposite-name terminal of the secondary winding of transformer T1 is connected to the drain of field-effect transistor Q1. The source of field-effect transistor Q1 is grounded. The gate of field-effect transistor Q1 is connected to one end of resistor R9. The other end of resistor R9 is connected to the pulse output of the secondary winding of the power supply circuit transformer. The output terminal of the operational amplifier N3A is connected to one end of resistor R13 and the current output unit. The other end of resistor R13 serves as the output terminal of the signal isolation converter. The current output unit includes an operational amplifier N4. The output terminal of the operational amplifier N4 is connected to one end of the shorting point J1 and the non-grounded end of the grounding resistor R10. The other end of the shorting point J1 is connected to one end of the resistor R12. The other end of the resistor R12 is connected to one end of the shorting point J3 and the output terminal of the operational amplifier N3A. The other end of the shorting point J3 is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the first input terminal of the operational amplifier N4. The second input terminal of the operational amplifier N4 is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the shorting point J2. The other end of the shorting point J2 is connected to the other end of the resistor R13. Specifically, when the output is a voltage signal, shorting point J1 is closed, and shorting points J2 and J3 are open; when the output is a current signal, shorting point J1 is open, and shorting points J2 and J3 are closed.

[0019] The small AC signal transmitted from the isolation circuit is rectified into the required signal waveform, the rectified waveform is converted into the required voltage or current signal, and the signal's load-carrying capacity is improved.

[0020] Preferably, the isolated power supply circuit includes a transformer T2, which includes one primary winding and two secondary windings. Both the same-named and opposite-named terminals of the primary winding of transformer T2 are connected to the symmetrical half-bridge circuit. The same-named terminal of the first secondary winding of transformer T2 is connected to the common terminal of a full-wave rectifier diode D1. The negative terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C3, and the positive terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C4. The opposite-named terminal of the first secondary winding of transformer T2 is grounded. The same-name terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D2, the negative terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C7. The center tap of the second secondary winding of transformer T2 is grounded; The opposite terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D3. The negative terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C7. The positive and negative terminals of full-wave rectifier diode D1, full-bridge rectifier diode D2, and full-bridge rectifier diode D3 all serve as output terminals of the power supply circuit to power the signal conversion module.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By acquiring current and voltage signals of different levels through a signal sampling circuit, the input voltage / current signal can be converted into a voltage / current signal output. 2. An anti-interference circuit is used to effectively attenuate the common-mode component of the voltage signal output by the signal sampling circuit, without affecting the differential-mode component (i.e., the useful signal), thereby achieving a high signal-to-noise ratio; 3. Set up a zero-adjustment and full-scale adjustment circuit to compensate for the lowest input value and correct the highest input value, ensuring high linearity and accuracy. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the control power supply part of Chinese utility model patent with patent number CN202679251U; Figure 2This is a schematic diagram of the signal isolation converter structure in one embodiment of the present invention; Figure 3 This is a schematic diagram of the signal isolation converter circuit in one embodiment of the present invention; Figure 4 This is a schematic diagram of the signal isolation converter circuit in another embodiment of the present invention; Figure 5 This is a schematic diagram of the response time of a signal isolation converter in one embodiment of the present invention; Figure 6 This is a schematic diagram of the output linearity of the signal isolation converter in one embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. However, it should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0024] If terms such as "first," "second," or "third" appear in the terminology, they are merely used to distinguish between identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0025] Example 1 Please refer to the following: Figure 2 As shown, this embodiment provides a signal isolation converter, including a signal sampling circuit, an isolation circuit, a chopper circuit, a rectified output amplifier circuit, and also includes an anti-interference circuit, an amplifier circuit, and a zero-adjustment / full-scale adjustment circuit. The signal sampling circuit, the anti-interference circuit, the amplification circuit, the isolation circuit, and the rectified output amplification circuit are connected in sequence; the chopper circuit is connected to the isolation circuit; one end of the zero-adjustment and full-scale adjustment circuit is connected to the input terminal of the amplification circuit; and the other end of the zero-adjustment and full-scale adjustment circuit is connected between the output terminal of the amplification circuit and the input terminal of the isolation circuit. The amplifier circuit includes a first input terminal and a second input terminal. The output terminal of the anti-interference circuit is connected to the first input terminal of the amplifier circuit, and one end of the zero-adjustment and full-scale adjustment circuit is connected to the second input terminal of the amplifier circuit. The signal sampling circuit is used to receive input voltage or input current signals from the input terminal and output a first voltage signal to the anti-interference circuit. The amplifier circuit receives the second voltage signal output by the anti-interference circuit. After the zero-adjustment and full-scale adjustment circuit compensates or corrects the second voltage signal, it outputs it to the isolation circuit through the output terminal of the amplifier circuit. The rectifier output amplifier circuit receives the isolation voltage signal output from the isolation circuit, and outputs the isolation voltage signal after converting it into a voltage or current signal.

[0026] The functions of each circuit module are as follows: The sampling circuit is used to convert the input signal, including but not limited to converting high voltage signals into low voltage signals, current signals into voltage signals, and sampling small signals at the mV level; The anti-interference circuit is used to filter out high-frequency interference signals and common-mode interference signals mixed in the input signal, thereby achieving a higher signal-to-noise ratio; The amplifier circuit is used to normalize the signals obtained by the sampling circuit from input signals of different types and sizes, and to ensure the consistent utilization of the subsequent chopper circuit. The zero-adjustment and full-scale adjustment circuits are used to achieve a consistent correspondence between the lowest input value and the lowest output value through compensation by the zero-adjustment circuit, and to achieve a consistent correspondence between the highest input value and the highest output value through correction by the full-scale adjustment circuit, so as to achieve higher precision and linearity. Chopper circuits are used to achieve isolated transmission of input and output signals. The signal needs to be "chopped" into multiple parts and converted into small AC signals in order to be transmitted through the magnetic isolation of the transformer in the isolation circuit. Isolation circuits are used to achieve signal isolation and consistent signal transmission by transmitting small AC signals from the primary side of a transformer to the secondary side via a magnetic field. The rectifier output amplifier circuit is used to rectify the small AC signal transmitted from the isolation circuit into the required signal waveform. Then, through the output amplifier circuit, the rectified waveform is converted into the required voltage or current signal, and the signal's load-carrying capacity is improved. At the same time, a protection circuit is added to protect the device from damage when the output terminal is under abnormal load.

[0027] Example 2 Please refer to the following: Figure 3 As shown, this embodiment is a further solution of embodiment 1, and further illustrates the possible specific implementation scheme of the signal isolation converter based on embodiment 1.

[0028] This embodiment also includes an oscillation circuit, a symmetrical half-bridge circuit, and an isolation power supply circuit for powering the signal isolation converter, which are connected in sequence. The isolation power supply circuit is also connected to the anti-interference circuit, the amplification circuit, the zero-adjustment and full-scale adjustment circuit, and the output rectifier amplification circuit.

[0029] The oscillation circuit is used to configure a fixed frequency and dead time through RC design. The oscillation circuit has two functions: one is to drive the subsequent stage to ensure the isolated power supply of the converter, and the other is to drive the chopper circuit of the signal conversion section to realize the signal transmission. No additional control signal is required. The level of the push-pull circuit in the isolated power supply is directly used as the driving signal of the chopper circuit, which is simple to control. The isolated power supply circuit is used to provide power to the stages before and after signal conversion through a symmetrical half-bridge circuit, using a transformer for isolation and rectification.

[0030] As one possible implementation, the signal sampling circuit includes a voltage divider sampling resistor R3, one end of which serves as the first signal input terminal of the signal sampling circuit, and the other end of which serves as the second signal input terminal of the signal sampling circuit, and the second signal input terminal of the signal sampling circuit is grounded.

[0031] In a preferred implementation, the signal sampling circuit includes a voltage divider sampling resistor R1. One end of the voltage divider sampling resistor R1 serves as the first signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R1 serves as the first output terminal of the signal sampling circuit and is connected to the first input terminal of the anti-interference circuit. The other end of the voltage divider sampling resistor R1 is also connected to one end of a voltage divider sampling resistor R3. The non-grounded end of the grounding resistor R4 serves as the second signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R3 is connected to the grounded end of the grounding resistor R4. The grounded end of the grounding resistor R4 also serves as the second output terminal of the signal sampling circuit and is connected to the second input terminal of the anti-interference circuit.

[0032] As one possible implementation, the anti-interference circuit is used to improve the common-mode rejection ratio and the signal-to-noise ratio of the input signal, and includes resistor R2, grounding resistor R5, resistor R6, and operational amplifier N1; one end of resistor R2 and the grounding end of grounding resistor R5 serve as the first input terminal and the second input terminal of the anti-interference circuit, respectively; the other end of resistor R2 and the non-grounding end of grounding resistor R5 are both connected to operational amplifier N1; resistor R6 is connected to two gain-configurable pins of operational amplifier N1 for configuring the input signal amplification factor; and the output terminal of operational amplifier N1 serves as the output terminal of the anti-interference circuit.

[0033] As one possible implementation, the amplifier circuit is used to perform signal normalization processing, including an operational amplifier N2A. The first input terminal of the operational amplifier N2A is connected to the output terminal of the anti-interference circuit, the second input terminal and the output terminal of the operational amplifier N2A are both connected to the zero-adjustment and full-scale adjustment circuit, and the output terminal of the operational amplifier N2A is also connected to the isolation circuit.

[0034] As one possible implementation, the zero-adjustment and full-scale adjustment circuit includes a zero-adjustment sub-circuit and a full-scale adjustment sub-circuit. The zero-adjustment sub-circuit is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor unit, respectively. The full-scale adjustment sub-circuit is connected to the other end of the feedback resistor unit and the output terminal of the operational amplifier N2A, respectively.

[0035] Preferably, the zero-adjustment sub-circuit includes a potentiometer P2, the full-scale adjustment sub-circuit includes a potentiometer P1, and the feedback resistor unit includes a resistor R7. The first and second fixed terminals of the potentiometer P2 are both connected to the isolation power supply circuit, and the sliding terminal of the potentiometer P2 is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor R7, respectively. The first fixed terminal and the sliding terminal of the potentiometer P1 are both connected to the other end of the feedback resistor R7, and the second fixed terminal of the potentiometer P1 is connected to the output terminal of the operational amplifier N2A.

[0036] As one possible implementation, the rectifier output amplifier circuit includes a voltage output unit and a current output unit, which are used to output voltage signals and current signals, respectively.

[0037] Preferably, the voltage output unit includes an operational amplifier N3A. The first input terminal of the operational amplifier N3A is connected to the same-name terminal of the secondary winding of transformer T1 and the non-grounded terminal of grounding capacitor C1. The second input terminal of the operational amplifier N3A is connected to one end of resistor R11. The other end of resistor R11 is connected to the non-grounded terminal of grounding resistor R10 and the current output unit. The opposite-name terminal of the secondary winding of transformer T1 is connected to the drain of field-effect transistor Q1. The source of field-effect transistor Q1 is grounded. The gate of field-effect transistor Q1 is connected to one end of resistor R9. The other end of resistor R9 is connected to the pulse output of the secondary winding of the power supply circuit transformer. The output terminal of the operational amplifier N3A is connected to one end of resistor R13 and the current output unit. The other end of resistor R13 serves as the output terminal of the signal isolation converter. The current output unit includes an operational amplifier N4. The output terminal of the operational amplifier N4 is connected to one end of the shorting point J1 and the non-grounded end of the grounding resistor R10. The other end of the shorting point J1 is connected to one end of the resistor R12. The other end of the resistor R12 is connected to one end of the shorting point J3 and the output terminal of the operational amplifier N3A. The other end of the shorting point J3 is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the first input terminal of the operational amplifier N4. The second input terminal of the operational amplifier N4 is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the shorting point J2. The other end of the shorting point J2 is connected to the other end of the resistor R13. Specifically, when the output is a voltage signal, shorting point J1 is closed, and shorting points J2 and J3 are open; when the output is a current signal, shorting point J1 is open, and shorting points J2 and J3 are closed.

[0038] As one possible implementation, the chopper circuit includes a field-effect transistor Q2, the drain of which is connected to the opposite terminal of the primary winding of the transformer T1, the source of which is grounded, the gate of which is connected to one end of a resistor R8, and the other end of the resistor R8 is connected to a power supply module.

[0039] Example 3 Please refer to the following: Figure 3 and Figure 4 As shown, this embodiment is a further solution of embodiment 1, and further illustrates the possible specific implementation scheme of the signal isolation converter based on embodiment 1.

[0040] As one possible implementation, the signal sampling circuit includes a voltage divider sampling resistor R3, one end of which serves as the first signal input terminal of the signal sampling circuit, and the other end of which serves as the second signal input terminal of the signal sampling circuit, and the second signal input terminal of the signal sampling circuit is grounded.

[0041] In a preferred implementation, the signal sampling circuit includes a voltage divider sampling resistor R1. One end of the voltage divider sampling resistor R1 serves as the first signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R1 serves as the first output terminal of the signal sampling circuit and is connected to the first input terminal of the anti-interference circuit. The other end of the voltage divider sampling resistor R1 is also connected to one end of a voltage divider sampling resistor R3. The non-grounded end of the grounding resistor R4 serves as the second signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R3 is connected to the grounded end of the grounding resistor R4. The grounded end of the grounding resistor R4 also serves as the second output terminal of the signal sampling circuit and is connected to the second input terminal of the anti-interference circuit.

[0042] As one possible implementation, the anti-interference circuit is used to improve the common-mode rejection ratio and the signal-to-noise ratio of the input signal, and includes a resistor R2, a grounding resistor R5, and an operational amplifier N1; one end of the resistor R2 and the grounding end of the grounding resistor R5 serve as the first input terminal and the second input terminal of the anti-interference circuit, respectively, and the other end of the resistor R2 and the non-grounding end of the grounding resistor R5 are both connected to the operational amplifier N1, and the output terminal of the operational amplifier N1 serves as the output terminal of the anti-interference circuit.

[0043] As one possible implementation, the amplifier circuit is used to perform signal normalization processing, including an operational amplifier N2A. The first input terminal of the operational amplifier N2A is connected to the output terminal of the anti-interference circuit, the second input terminal and the output terminal of the operational amplifier N2A are both connected to the zero-adjustment and full-scale adjustment circuit, and the output terminal of the operational amplifier N2A is also connected to the isolation circuit.

[0044] As one possible implementation, the zero-adjustment and full-scale adjustment circuit includes a zero-adjustment sub-circuit and a full-scale adjustment sub-circuit. The zero-adjustment sub-circuit is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor unit, respectively. The full-scale adjustment sub-circuit is connected to the other end of the feedback resistor unit and the output terminal of the operational amplifier N2A, respectively.

[0045] Preferably, the zero-adjustment sub-circuit includes a potentiometer P2, the full-scale adjustment sub-circuit includes a potentiometer P1, and the feedback resistor unit includes a resistor R7. The first and second fixed terminals of the potentiometer P2 are both connected to the isolation power supply circuit, and the sliding terminal of the potentiometer P2 is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor R7, respectively. The first fixed terminal and the sliding terminal of the potentiometer P1 are both connected to the other end of the feedback resistor R7, and the second fixed terminal of the potentiometer P1 is connected to the output terminal of the operational amplifier N2A.

[0046] As one possible implementation, the rectifier output amplifier circuit includes a voltage output unit and a current output unit, which are used to output voltage signals and current signals, respectively.

[0047] Preferably, the voltage output unit includes an operational amplifier N3A. The first input terminal of the operational amplifier N3A is connected to the same-name terminal of the secondary winding of transformer T1 and the non-grounded terminal of grounding capacitor C1. The second input terminal of the operational amplifier N3A is connected to one end of resistor R11. The other end of resistor R11 is connected to the non-grounded terminal of grounding resistor R10 and the current output unit. The opposite-name terminal of the secondary winding of transformer T1 is connected to the drain of field-effect transistor Q1. The source of field-effect transistor Q1 is grounded. The gate of field-effect transistor Q1 is connected to one end of resistor R9. The other end of resistor R9 is connected to the pulse output of the secondary winding of the power supply circuit transformer. The output terminal of the operational amplifier N3A is connected to one end of resistor R13 and the current output unit. The other end of resistor R13 serves as the output terminal of the signal isolation converter. The current output unit includes an operational amplifier N4. The output terminal of the operational amplifier N4 is connected to one end of the shorting point J1 and the non-grounded end of the grounding resistor R10. The other end of the shorting point J1 is connected to one end of the resistor R12. The other end of the resistor R12 is connected to one end of the shorting point J3 and the output terminal of the operational amplifier N3A. The other end of the shorting point J3 is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the first input terminal of the operational amplifier N4. The second input terminal of the operational amplifier N4 is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the shorting point J2. The other end of the shorting point J2 is connected to the other end of the resistor R13. Specifically, when the output is a voltage signal, shorting point J1 is closed, and shorting points J2 and J3 are open; when the output is a current signal, shorting point J1 is open, and shorting points J2 and J3 are closed.

[0048] As one possible implementation, the chopper circuit includes a field-effect transistor Q2, the drain of which is connected to the opposite terminal of the primary winding of the transformer T1, the source of which is grounded, the gate of which is connected to one end of a resistor R8, and the other end of the resistor R8 is connected to a power supply module.

[0049] In one possible implementation, the symmetrical half-bridge circuit includes resistors R17 and R18. One end of resistor R17 and one end of resistor R18 are connected to the high-level output terminal and the low-level output terminal of the oscillation circuit, respectively. The other ends of resistors R17 and R18 are connected to the gate of field-effect transistor Q3 and the gate of field-effect transistor Q4, respectively. The source of field-effect transistor Q3 is connected to the drain of field-effect transistor Q4. The source of field-effect transistor Q4 is grounded. The drain of field-effect transistor Q3 is connected to one end of capacitor C2. The other end of capacitor C2 is connected to the non-grounded end of grounding capacitor C5. The other end of capacitor C2 and the drain of field-effect transistor Q4 are both connected to the isolated power supply circuit.

[0050] As one possible implementation, the isolated power supply circuit includes a transformer T2, which includes one primary winding and two secondary windings. Both the same-named and opposite-named terminals of the primary winding of transformer T2 are connected to the symmetrical half-bridge circuit. The same-named terminal of the first secondary winding of transformer T2 is connected to the common terminal of a full-wave rectifier diode D1. The negative terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C3, and the positive terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C4. The opposite-named terminal of the first secondary winding of transformer T2 is grounded. The same-name terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D2, the negative terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C7. The center tap of the second secondary winding of transformer T2 is grounded; The opposite terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D3. The negative terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C7. The positive and negative terminals of full-wave rectifier diode D1, full-bridge rectifier diode D2, and full-bridge rectifier diode D3 all serve as output terminals of the power supply circuit to power the signal conversion module.

[0051] The oscillation circuit is used to configure a fixed frequency and dead time through RC design. The oscillation circuit has two functions: one is to drive the subsequent stage to ensure the isolated power supply of the converter, and the other is to drive the chopper circuit of the signal conversion section to realize the signal transmission. No additional control signal is required. The level of the push-pull circuit in the isolated power supply is directly used as the driving signal of the chopper circuit, which is simple to control. The isolated power supply circuit is used to provide power to the stages before and after signal conversion through a symmetrical half-bridge circuit, using a transformer for isolation and rectification.

[0052] As a preferred embodiment, the signal isolation converter provided in this embodiment further includes a protection sub-circuit, which includes resistors R19 and R20, a field-effect transistor Q5, and a field-effect transistor Q6. One end of resistor R19 is connected to the output terminal of operational amplifier N3A, and the other end of resistor R19 is connected to the base of transistor Q5 and the collector of transistor Q6, respectively. The emitter of transistor Q5 is connected to the base of transistor Q6 and one end of resistor R20, respectively. The collector of transistor Q5 is connected to the power supply, and the emitter of transistor Q6 and the other end of resistor R20 are both connected to one end of resistor R13.

[0053] This embodiment isolates the power signal, input signal, and output signal. The signal conversion circuit and power supply circuit, which consist of a sampling circuit, anti-interference circuit, amplification circuit, zero-adjustment circuit, full-scale adjustment circuit, chopper circuit, isolation circuit, and rectifier output amplification circuit, achieve synchronous driving, reduce the influence of the power supply circuit on the signal at the switching moment, reduce the difficulty of the switching drive circuit, and add a protection circuit to protect the device from damage when the output terminal is under abnormal load. It can be modularly packaged, simplifying production and facilitating mass production.

[0054] Example 4 Please refer to the example below. Figure 5 and Figure 6 As shown, this embodiment is based on the experimental verification of Embodiments 1-3, and the results of response time and output linearity are obtained.

[0055] Based on the above results, it can be concluded that the signal converter provided by this utility model has the characteristics of high response, high precision, and low distortion. Moreover, it is based on modular packaging and is simple to manufacture, which is conducive to mass production.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A signal isolation converter, comprising a signal sampling circuit, an isolation circuit, a chopper circuit, and a rectified output amplifier circuit, characterized in that, Also includes: Anti-interference circuit, amplifier circuit, zero-adjustment / full-scale adjustment circuit; The signal sampling circuit, the anti-interference circuit, the amplification circuit, the isolation circuit, and the rectified output amplification circuit are connected in sequence; the chopper circuit is connected to the isolation circuit; one end of the zero-adjustment and full-scale adjustment circuit is connected to the input terminal of the amplification circuit; and the other end of the zero-adjustment and full-scale adjustment circuit is connected between the output terminal of the amplification circuit and the input terminal of the isolation circuit. The signal sampling circuit is used to receive input voltage or input current signals from the input terminal and output a first voltage signal to the anti-interference circuit. The amplifier circuit receives the second voltage signal output by the anti-interference circuit. After the zero-adjustment and full-scale adjustment circuit compensates or corrects the second voltage signal, it outputs it to the isolation circuit through the output terminal of the amplifier circuit. The rectifier output amplifier circuit receives the isolation voltage signal output from the isolation circuit, and outputs the isolation voltage signal after converting it into a voltage or current signal.

2. The signal isolation converter according to claim 1, characterized in that, The signal sampling circuit includes a voltage divider sampling resistor R3. One end of the voltage divider sampling resistor R3 serves as the first signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R3 serves as the second signal input terminal of the signal sampling circuit. The second signal input terminal of the signal sampling circuit is grounded.

3. The signal isolation converter according to claim 1, characterized in that, The signal sampling circuit includes a voltage divider sampling resistor R1. One end of the voltage divider sampling resistor R1 serves as the first signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R1 serves as the first output terminal of the signal sampling circuit and is connected to the first input terminal of the anti-interference circuit. The other end of the voltage divider sampling resistor R1 is also connected to one end of a voltage divider sampling resistor R3. The non-grounded end of the grounding resistor R4 serves as the second signal input terminal of the signal sampling circuit, and the other end of the voltage divider sampling resistor R3 is connected to the grounded end of the grounding resistor R4. The grounded end of the grounding resistor R4 also serves as the second output terminal of the signal sampling circuit and is connected to the second input terminal of the anti-interference circuit.

4. The signal isolation converter according to claim 1, characterized in that, The anti-interference circuit is used to improve the common-mode rejection ratio and the signal-to-noise ratio of the input signal. It includes a resistor R2, a grounding resistor R5, a resistor R6, and an operational amplifier N1. One end of the resistor R2 and the grounding end of the grounding resistor R5 serve as the first and second input terminals of the anti-interference circuit, respectively. The other end of the resistor R2 and the non-grounding end of the grounding resistor R5 are both connected to the operational amplifier N1. The resistor R6 is connected to two gain-configurable pins of the operational amplifier N1 for configuring the input signal amplification factor. The output terminal of the operational amplifier N1 serves as the output terminal of the anti-interference circuit.

5. The signal isolation converter according to claim 1, characterized in that, The amplification circuit is used to perform signal normalization processing and includes an operational amplifier N2A. The first input terminal of the operational amplifier N2A is connected to the output terminal of the anti-interference circuit. The second input terminal and the output terminal of the operational amplifier N2A are both connected to the zero-adjustment and full-scale adjustment circuit. The output terminal of the operational amplifier N2A is connected to the isolation circuit.

6. The signal isolation converter according to claim 4 or 5, characterized in that, It also includes an oscillation circuit, a symmetrical half-bridge circuit, and an isolation power supply circuit for powering the signal isolation converter, which are connected in sequence. The isolation power supply circuit is also connected to the anti-interference circuit, the amplification circuit, the zero-adjustment and full-scale adjustment circuit, and the output rectifier and amplification circuit, respectively.

7. The signal isolation converter according to claim 6, characterized in that, The zero-adjustment and full-scale adjustment circuit includes a zero-adjustment sub-circuit and a full-scale adjustment sub-circuit. The zero-adjustment sub-circuit is connected to the second input terminal of the amplifier circuit and one end of the feedback resistor unit, respectively. The full-scale adjustment sub-circuit is connected to the other end of the feedback resistor unit and the output terminal of the amplifier circuit, respectively. The zero-adjustment sub-circuit includes potentiometer P2, the full-scale adjustment sub-circuit includes potentiometer P1, and the feedback resistor unit includes resistor R7. The first and second fixed terminals of the potentiometer P2 are both connected to the isolation power supply circuit, and the sliding terminal of the potentiometer P2 is connected to the second input terminal of the operational amplifier N2A and one end of the feedback resistor R7, respectively. The first fixed terminal and the sliding terminal of the potentiometer P1 are both connected to the other end of the feedback resistor R7, and the second fixed terminal of the potentiometer P1 is connected to the output terminal of the operational amplifier N2A.

8. The signal isolation converter according to claim 6, characterized in that, The rectifier output amplifier circuit includes a voltage output unit and a current output unit, which are used to output voltage signals and current signals, respectively.

9. The signal isolation converter according to claim 8, characterized in that, The voltage output unit includes an operational amplifier N3A. The first input terminal of operational amplifier N3A is connected to the same-name terminal of the secondary winding of transformer T1 and the non-grounded terminal of grounding capacitor C1. The second input terminal of operational amplifier N3A is connected to one end of resistor R11. The other end of resistor R11 is connected to the non-grounded terminal of grounding resistor R10 and the current output unit. The opposite-name terminal of the secondary winding of transformer T1 is connected to the drain of field-effect transistor Q1. The source of field-effect transistor Q1 is grounded. The gate of field-effect transistor Q1 is connected to one end of resistor R9. The other end of resistor R9 is connected to the secondary pulse output of the power supply circuit transformer. The output terminal of operational amplifier N3A is connected to one end of resistor R13 and the current output unit. The other end of resistor R13 serves as the output terminal of a signal isolation converter. The current output unit includes an operational amplifier N4. The output terminal of the operational amplifier N4 is connected to one end of the shorting point J1 and the non-grounded end of the grounding resistor R10. The other end of the shorting point J1 is connected to one end of the resistor R12. The other end of the resistor R12 is connected to one end of the shorting point J3 and the output terminal of the operational amplifier N3A. The other end of the shorting point J3 is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the first input terminal of the operational amplifier N4. The second input terminal of the operational amplifier N4 is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the shorting point J2. The other end of the shorting point J2 is connected to the other end of the resistor R13. Specifically, when the output is a voltage signal, shorting point J1 is closed, and shorting points J2 and J3 are open; when the output is a current signal, shorting point J1 is open, and shorting points J2 and J3 are closed.

10. The signal isolation converter according to claim 9, characterized in that, The isolated power supply circuit includes a transformer T2, which includes one primary winding and two secondary windings. Both the same-named and opposite-named terminals of the primary winding of transformer T2 are connected to the symmetrical half-bridge circuit. The same-named terminal of the first secondary winding of transformer T2 is connected to the common terminal of a full-wave rectifier diode D1. The negative terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C3, and the positive terminal of the full-wave rectifier diode D1 is connected to the non-grounded terminal of a grounding capacitor C4. The opposite-named terminal of the first secondary winding of transformer T2 is grounded. The same-name terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D2, the negative terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D2 is connected to the non-grounded terminal of grounding capacitor C7. The center tap of the second secondary winding of transformer T2 is grounded; The opposite terminal of the second secondary winding of transformer T2 is connected to the common terminal of full-bridge rectifier diode D3. The negative terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C6, and the positive terminal of full-bridge rectifier diode D3 is connected to the non-grounded terminal of grounding capacitor C7. The positive and negative terminals of full-wave rectifier diode D1, full-bridge rectifier diode D2, and full-bridge rectifier diode D3 all serve as output terminals of the power supply circuit to power the signal conversion module.

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