阅读说明：本技术 基于变压器的模拟信号隔离电路 (Analog signal isolation circuit based on transformer ) 是由 刘溢 孙富韬 孙海涛 武东健 吴佳灵 徐辉 陈瑞典 卢超 王阔传 于 2020-12-16 设计创作，主要内容包括：本发明公开了一种基于变压器的模拟信号隔离电路,包括隔离变压器、驱动单元、输出单元和反馈单元,其中,所述驱动单元通过驱动绕线绕组绕制于所述隔离变压器的原边侧,所述反馈单元通过反馈绕线绕组绕制于隔离变压器的原边侧,所述驱动绕线绕组与所述反馈绕线绕组并联绕制于所述隔离变压器的原边侧,所述输出单元通过输出绕线绕组绕制于所述隔离变压器的副边侧,所述驱动绕线绕组绕线匝数、反馈绕线绕组绕线匝数、输出绕线绕组绕线匝数之比为1:1:1。通过将输入侧和输出侧的开关管与隔离变压器的原边侧和副边侧绕组线圈串联的方式,实现了输入输出信号的电气隔离,防止了外部干扰对内部信号的影响,提高了抗干扰能力。(The invention discloses an analog signal isolation circuit based on a transformer, which comprises an isolation transformer, a driving unit, an output unit and a feedback unit, wherein the driving unit is wound on the primary side of the isolation transformer through a driving winding, the feedback unit is wound on the primary side of the isolation transformer through a feedback winding, the driving winding and the feedback winding are wound on the primary side of the isolation transformer in parallel, the output unit is wound on the secondary side of the isolation transformer through an output winding, and the ratio of the number of winding turns of the driving winding to the number of winding turns of the feedback winding to the number of winding turns of the output winding is 1:1: 1. The input and output signals are electrically isolated by connecting the switching tubes on the input side and the output side in series with the primary side and secondary side winding coils of the isolation transformer, so that the influence of external interference on internal signals is prevented, and the anti-interference capability is improved.)

1. The transformer-based analog signal isolation circuit is characterized by comprising an isolation transformer, a driving unit, an output unit and a feedback unit, wherein the driving unit is used for receiving an input voltage signal and outputting a driving voltage according to a control signal requirement; the driving unit is wound on the primary side of the isolation transformer through a driving winding, the feedback unit is wound on the primary side of the isolation transformer through a feedback winding, the driving winding and the feedback winding are wound on the primary side of the isolation transformer in parallel, the output unit is wound on the secondary side of the isolation transformer through an output winding, and the ratio of the number of winding turns of the driving winding to the number of winding turns of the feedback winding to the number of winding turns of the output winding is 1:1: 1.

2. The isolation circuit of claim 1, wherein the driving unit comprises: the driving winding is connected with the driving circuit at a first end, the second end of the driving winding is electrically connected with the drain electrode of the first switch tube, the grid electrode of the first switch tube is electrically connected with one end of the third resistor, the source electrode of the first switch tube is connected with an internal signal ground end, and the other end of the third resistor receives a first control signal.

3. The isolation circuit of claim 1 or 2, wherein the drive circuit comprises: a first resistor, a second resistor, a sixth resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first integrated operational amplifier, one end of the first resistor and one end of the first capacitor are respectively and electrically connected with the positive input end of the first integrated operational amplifier, one end of the second resistor is electrically connected with the reverse input end of the first integrated operational amplifier, one end of the second capacitor and one end of the sixth resistor are respectively connected with the output end of the first integrated operational amplifier, the other end of the second capacitor is electrically connected with the other end of the second resistor, the other end of the first resistor is electrically connected with an input voltage, the other end of the first capacitor is connected with an internal signal ground end, the other end of the sixth resistor is respectively and electrically connected with the other end of the fourth capacitor and the second end of the driving winding, and the other end of the fourth capacitor is connected with the internal signal ground end.

4. The isolation circuit of claim 3, wherein the feedback unit comprises: the fifth capacitor, the fourth resistor, the fifth resistor, the feedback winding and the second switch tube; one end of the fifth capacitor is respectively electrically connected with the first end of the feedback winding and the other end of the second resistor, the other end of the second capacitor is connected with the internal signal ground end, the second end of the feedback winding is electrically connected with the drain electrode of the second switch tube, the two ends of the fifth resistor are respectively connected with the source electrode and the grid electrode of the second switch tube, one end of the fifth resistor connected with the source electrode of the second switch tube is connected with the internal signal ground end, one end of the fifth resistor connected with the grid electrode of the second switch tube is connected with one end of the fourth resistor, and the two ends of the fourth resistor are respectively connected with the grid electrode of the second switch tube and the grid electrode of the first switch tube.

5. The isolation circuit of claim 1, wherein the output unit comprises: the output winding first end is electrically connected with one end of the output circuit, the second end of the output winding is electrically connected with the drain electrode of the third switch, two ends of the eighth resistor are respectively connected with the source electrode of the third switch tube and the grid electrode of the third switch tube, one end of the fifth resistor connected with the source electrode of the third switch tube is connected with an external signal ground end, the other end of the fifth resistor connected with the grid electrode of the third switch tube is electrically connected with one end of the seventh resistor, and the other end of the seventh resistor receives a second control signal.

6. The isolation circuit of claim 2 or 5, wherein the first control signal and the second control signal are at the same frequency and in phase.

7. The isolation circuit of claim 4 or 5, wherein the drive winding first end, the feedback winding first end, and the output winding first end are homonymous ends.

8. The isolation circuit of claim 4 or 5, wherein diodes are respectively connected between the source and the drain of the first switching tube, the second switching tube and the third switching tube.

Technical Field

The invention belongs to the technical field of signal isolation, and particularly relates to an analog signal isolation circuit based on a transformer.

Background

In the signal conditioning process of the sensor such as temperature, pressure and the like, in order to reduce the influence of the external environment on the internal circuit and improve the anti-interference performance of the circuit, the input signal and the output signal of the sensor need to be electrically isolated. A simpler way is by an opto-isolator chip. However, the optical coupling isolation linearity is not good, and the measurement error of the sensor is increased. How to overcome external interference, reduce the influence of external factors on internal circuits, and realize electrical isolation of input and output signals of the sensor, so that the input and output signals have good linearity and precision is a technical problem to be solved urgently at present.

Disclosure of Invention

The embodiment of the invention provides an analog signal isolation circuit based on a transformer, which overcomes the influence of external interference on an internal circuit, realizes the electrical isolation of input and output signals of a sensor, and has good linearity and precision. .

In a first aspect of the present invention, an analog signal isolation circuit based on a transformer is provided, where the isolation circuit includes an isolation transformer, a driving unit, an output unit, and a feedback unit, where the driving unit is configured to receive an input voltage signal and output a driving voltage according to a control signal requirement, the output unit is configured to output an output voltage according to the driving voltage of the driving unit, and the feedback unit is configured to output a feedback voltage to the driving unit according to the control signal requirement; the driving unit is wound on the primary side of the isolation transformer through a driving winding, the feedback unit is wound on the primary side of the isolation transformer through a feedback winding, the driving winding and the feedback winding are wound on the primary side of the isolation transformer in parallel, the output unit is wound on the secondary side of the isolation transformer through an output winding, and the ratio of the number of winding turns of the driving winding to the number of winding turns of the feedback winding to the number of winding turns of the output winding is 1:1: 1.

According to a first aspect, in a first possible implementation form of the isolation circuit, the driving unit includes: the driving winding is connected with the driving circuit at a first end, the second end of the driving winding is electrically connected with the drain electrode of the first switch tube, the grid electrode of the first switch tube is electrically connected with one end of the third resistor, the source electrode of the first switch tube is connected with an internal signal ground end, and the other end of the third resistor receives a first control signal.

In a second possible implementation form of the driving unit according to the first aspect as such or the first possible implementation form of the first aspect, the driving circuit comprises: a first resistor, a second resistor, a sixth resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first integrated operational amplifier, one end of the first resistor and one end of the first capacitor are respectively and electrically connected with the positive input end of the first integrated operational amplifier, one end of the second resistor is electrically connected with the reverse input end of the first integrated operational amplifier, one end of the second capacitor and one end of the sixth resistor are respectively connected with the output end of the first integrated operational amplifier, the other end of the second capacitor is electrically connected with the other end of the second resistor, the other end of the first resistor is electrically connected with an input voltage, the other end of the first capacitor is connected with an internal signal ground end, the other end of the sixth resistor is respectively and electrically connected with the other end of the fourth capacitor and the second end of the driving winding, and the other end of the fourth capacitor is connected with the internal signal ground end.

According to a second possible implementation manner of the first aspect, in a third possible implementation manner of the isolation circuit, the feedback unit includes: the fifth capacitor, the fourth resistor, the fifth resistor, the feedback winding and the second switch tube; one end of the fifth capacitor is respectively electrically connected with the first end of the feedback winding and the other end of the second resistor, the other end of the second capacitor is connected with the internal signal ground end, the second end of the feedback winding is electrically connected with the drain electrode of the second switch tube, the two ends of the fifth resistor are respectively connected with the source electrode and the grid electrode of the second switch tube, one end of the fifth resistor connected with the source electrode of the second switch tube is connected with the internal signal ground end, one end of the fifth resistor connected with the grid electrode of the second switch tube is connected with one end of the fourth resistor, and the two ends of the fourth resistor are respectively connected with the grid electrode of the second switch tube and the grid electrode of the first switch tube.

According to the first aspect, in a fourth possible implementation manner of the isolation circuit, the output unit includes: the output winding first end is electrically connected with one end of the output circuit, the second end of the output winding is electrically connected with the drain electrode of the third switch, two ends of the eighth resistor are respectively connected with the source electrode of the third switch tube and the grid electrode of the third switch tube, one end of the fifth resistor connected with the source electrode of the third switch tube is connected with an external signal ground end, the other end of the fifth resistor connected with the grid electrode of the third switch tube is electrically connected with one end of the seventh resistor, and the other end of the seventh resistor receives a second control signal.

According to the first implementation manner of the first aspect or the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner of the isolation circuit, the first control signal and the second control signal have the same frequency and the same phase.

In a sixth possible implementation manner of the isolation circuit according to the third implementation manner of the first aspect or the fourth possible implementation manner of the first aspect, the first end of the driving winding, the first end of the feedback winding, and the first end of the output winding are homonymous ends.

According to a third implementation manner of the first aspect or the fourth possible implementation manner of the first aspect, in a seventh possible implementation manner of the isolation circuit, diodes are respectively connected between the source and the drain of the first switching tube, the second switching tube, and the third switching tube.

The invention has the following beneficial effects: the input side and the output side are electrically isolated by connecting the switching tubes of the input side and the output side in series with the primary side and secondary side winding coils of the isolation transformer and setting control signals on the input side and the output side, so that the influence of external interference on internal signals is prevented, and the anti-interference capability is improved. Meanwhile, the isolation circuit has good linearity and precision.

Drawings

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

Fig. 1 is a diagram of an analog signal isolation circuit based on a transformer according to an embodiment of the present invention.

With the foregoing drawings in mind, certain embodiments of the disclosure have been shown and described in more detail below. These drawings and written description are not intended to limit the scope of the disclosed concepts in any way, but rather to illustrate the concepts of the disclosure to those skilled in the art by reference to specific embodiments.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

The invention designs an analog signal isolation circuit based on a transformer. The circuit comprises an isolation transformer, a driving circuit, an output circuit, a feedback circuit and a corresponding control signal.

The isolation transformer T1 comprises a driving winding (5 th tap, 6 th tap), an output winding (1 st tap, 2 nd tap) and a feedback winding (3 rd tap, 4 th tap), and is completely wound in a three-wire winding mode according to the ratio of 1:1:1, so that the performances of the three windings are completely consistent theoretically. The 2 nd, 4 th and 6 th taps are homonymous terminals. The isolation transformer is a transformer with an input winding and an output winding electrically isolated, and avoids touching an electrified body accidentally and simultaneously and isolating respective currents of primary and secondary windings of the transformer. The input end and the output end of the isolation transformer are completely 'broken circuit' isolated, so that the input end of the transformer is effectively and well filtered, and pure power supply voltage is provided for electric equipment.

The driving circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a sixth resistor R6, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first integrated operational amplifier U1, a first switching tube N-channel enhancement type field effect tube Q1A and a driving winding (5 th and 6 th taps) of an isolation transformer T1. One end of the first resistor R1 is connected to the input signal Vin, and the other end is connected to one end of the first capacitor C1 and the non-inverting input terminal of the first integrated operational amplifier U1. The other end of the first capacitor C1 is connected to the internal signal ground GND. One end of the second resistor R2 is connected to the inverting input terminal of the first integrated operational amplifier, and the other end is connected to one end of the second capacitor C2. The other end of the first integrated operational amplifier C2 is connected to the output end of the first integrated operational amplifier and one end of the sixth resistor R6. The other end of the sixth R6 is connected to one end of the fourth capacitor C4, and the other end of the fourth C4 is connected to the internal signal ground GND. The 6 th tap of the driving winding of the isolation transformer T1 is connected with the common end of the sixth resistor R6 and the fourth capacitor C4, and the 5 th tap is connected with the drain D of the first switch tube Q1A. The source S of the first switch tube Q1A is connected with the ground GND of the internal signal; the grid G of the first switch tube Q1A is connected with one end of a third resistor R3, and the other end of the third resistor R3 is connected with a control signal 1 from the 1 st tap of the secondary winding of the power transformer T2. The 1 st tap and the 3 rd tap of the power transformer T2 are terminals of the same name.

The output circuit comprises a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a second integrated operational amplifier U2, a seventh resistor R7, an eighth resistor R8, a third switching tube N-channel enhancement type field effect tube Q2A and an output winding (1 st and 2 nd taps) of the isolation transformer. After being connected in parallel, the sixth capacitor C6 and the seventh capacitor C7 are connected with an external signal ground GND1 at one end; the other end is connected with the 2 nd tap of the output winding of the T1 and the non-inverting input end of the second integrated operational amplifier U2. The inverting input terminal and the output terminal of the second integrated operational amplifier U2 are connected to form an output terminal, which is connected to Vout. The 1 st tap of the output winding of the T1 is connected with the drain D of the Q2A; the source S of the Q2A is connected with an external signal ground GND 1; the grid G of the Q2A is connected with the common end of the seventh resistor R7 and the eighth resistor R8; the other end of the seventh resistor R7 is connected with a control signal 2 from the 3 rd tap of the primary winding of the power transformer T2; the other end of the eighth resistor R8 is connected to the external signal ground GND 1.

The feedback circuit comprises a fourth resistor R4, a fifth resistor R5, a fifth capacitor C5, a second switch tube N-channel enhancement mode field effect tube Q1B and a feedback winding (3 rd and 4 th taps) of an isolation transformer. One end of the fifth capacitor C5 is connected to the common terminal of the second resistor R2 and the second capacitor C2, and the other end is connected to the internal signal ground GND. The 4 th tap of the feedback winding of the isolation transformer T1 is connected with the common end of the second resistor R2, the second capacitor C2 and the fifth capacitor C5, and the 3 rd tap is connected with the drain D of the second switch tube Q1B. The source S of the second switch tube Q1B is connected with the internal signal ground GND; the grid G of the second switch tube is connected with the common end of the fourth resistor R4 and the fifth resistor R5. The other end of the fourth resistor R4 is connected with the common end of the third resistor R3 and the second switch tube Q1A; the other end of the fifth resistor R5 is connected with the internal signal ground GND.

The isolation principle of the circuit is as follows: t1 is a signal isolation transformer, which comprises three windings of a driving winding (5 th tap and 6 th tap), an output winding (1 st tap and 2 nd tap) and a feedback winding (3 rd tap and 4 th tap), wherein the turn ratio is 1:1:1, and the three windings are wound in a three-wire winding manner, so that the performances of the three windings are completely consistent theoretically. Vin is the circuit input voltage; vdrive is a driving voltage output by the operational amplifier U1, and is converted into an alternating voltage to drive a driving winding (5 th and 6 th taps) of T1 after being chopped by a first switching tube Q1A; vout is the output voltage followed by the second integrated operational amplifier U2, and Vback is the feedback voltage. The relationship between the primary side and the secondary side of the isolation transformer T1 and the virtual short and the virtual break of the integrated operational amplifier U1 can be easily obtained:

Vout＝Vback＝Vin (1)

namely, the complete following and isolation of the output voltage Vout to the input voltage Vin are realized.

The control signal 1 and the control signal 2 are square wave signals with the same frequency, the same phase and mutual electrical isolation, and are respectively taken from the 1 st tap of the secondary side and the 3 rd tap of the primary side winding of the power transformer T2 in this example. The N-channel enhancement type field effect transistors Q1A, Q1B and Q2A are controlled to be synchronously switched on and off, the chopping and rectifying functions are completed, and the conversion between direct current/alternating current and alternating current/direct current is realized. The fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C46 and the seventh capacitor C7 are filter capacitors, and therefore the level is guaranteed to be smooth.

According to the technical scheme, the input side and the output side are connected with the primary side and the secondary side winding coils of the isolation transformer in series, and the input side and the output side are provided with the control signals, so that the electrical isolation of input and output signals is realized, the influence of external interference on internal signals is prevented, and the anti-interference capability is improved. Meanwhile, the isolation circuit has good linearity and precision.

It should be understood that the above-described embodiments are merely exemplary for illustrating the application of the present method and are not limiting, and that various other modifications and changes may be made by those skilled in the art based on the above description for studying the related problems. Therefore, the protection scope of the present invention should be defined by the appended claims.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

The above-described embodiments of the electronic device and the like are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may also be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present invention, and are not limited thereto; although embodiments of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.