Analog quantity isolation transmission device and method based on transformer

Abstract

The invention discloses a transformer-based analog quantity isolation transmission device and method. The transformer-based analog quantity isolation transmission device comprises an analog quantity input module, a symmetric square wave transformation module, a transformer module, a rectifier module and an analog quantity output module, the analog quantity input module is used for inputting analog quantity; the symmetrical square wave conversion module is used for converting the input analog quantity into symmetrical alternating-current square waves; the transformer module is used for transmitting the converted alternating-current square wave from the primary side of a transformer to the secondary side of the transformer, and isolation of analog quantity is achieved through the transformer; the rectifier module is used for rectifying the alternating-current square wave isolated by the transformer to realize analog quantity reduction; and the analog quantity output module is used for outputting analog quantity. According to the invention, the analog quantity can be directly transmitted based on the transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a transformer-based analog quantity isolation transmission device and method. Background Art

[0002] Transformers are generally used to transfer energy and change voltage and current values. They are also often used to isolate digital signals. The so-called "isolation" or "electrical isolation" is to prevent the transfer of charge between the two isolated circuits. The present invention proposes a new use of transformers, that is, to perform isolated transmission of analog quantities based on transformers. Summary of the invention

[0003] The present invention provides a transformer-based analog quantity isolation transmission device and method, which performs isolation transmission of analog quantities based on the transformer.

[0004] The first embodiment of the present invention provides a transformer-based analog quantity isolation transmission device, the device comprising an analog quantity input module, a symmetrical square wave conversion module, a transformer module, a rectifier module and an analog quantity output module, the analog quantity input module is connected to the symmetrical square wave conversion module, the symmetrical square wave conversion module is connected to the primary side of the transformer module, the rectifier module is connected to the secondary side of the transformer module, and the analog quantity output module is connected to the rectifier module; Analog input module, used to input analog quantity; Symmetrical square wave conversion module, used to convert the input analog quantity into a symmetrical AC square wave; The transformer module is used to transfer the transformed AC square wave from the primary side of the transformer to the secondary side of the transformer, and to achieve the isolation of the analog quantity through the transformer; The rectifier module is used to rectify the AC square wave isolated by the transformer to restore the analog quantity; Analog output module, used to output analog quantity.

[0005] Furthermore, the symmetrical square wave conversion module is specifically used to convert the input analog quantity into a symmetrical AC square wave whose voltage amplitude is in a preset ratio with the voltage amplitude of the input analog quantity.

[0006] Furthermore, the symmetrical square wave conversion module includes a full-bridge converter, a half-bridge converter or a push-pull converter.

[0007] Furthermore, the rectification module includes: a rectification circuit including a diode, a synchronous rectification circuit including a controllable switch, a voltage doubling rectification circuit including a diode and a controllable switch, or an absolute value circuit including an operational amplifier.

[0008] Furthermore, the analog quantity input module is specifically used to input unipolar analog quantities or convert bipolar analog quantities into unipolar quantities before inputting.

[0009] Furthermore, the analog output module is specifically used to directly output a unipolar analog quantity or to restore it to a bipolar quantity before outputting it.

[0010] Further, the symmetrical square wave conversion module includes an oscillator, a switch S, an operational amplifier U1, a resistor R1 and a resistor R2; A first fixed end of the switch S is connected to the analog input end, a second fixed end of the switch S is connected to the GND end, a positive input end of the operational amplifier U1 is connected to the moving end of the switch S, an output of the oscillator drives the moving end of the switch S to switch back and forth between the first fixed end and the second fixed end, an output end of the operational amplifier U1 is connected to the primary of the transformer, a first end of the resistor R2 is connected to a node between the analog input end and the first fixed end of the switch S, a second end of the resistor R2 is connected to the negative input end of the operational amplifier U1, a first end of the resistor R1 is connected to a node between the resistor R2 and the negative input end of the operational amplifier U1, and a second end of the resistor R1 is connected to the output end of the operational amplifier U1.

[0011] Furthermore, the symmetrical square wave conversion module also includes a capacitor C, which is connected in series between the output end of the operational amplifier U1 and the primary of the transformer, and the second end of the resistor R1 is connected to the node between the output end of the operational amplifier U1 and the capacitor C.

[0012] A second embodiment of the present invention provides a transformer-based analog quantity isolation transmission method, the method comprising: Input analog quantity; Convert the input analog quantity into a symmetrical AC square wave; The transformed AC square wave is transferred from the primary of the transformer to the secondary of the transformer, and the analog quantity is isolated through the transformer; Restore the AC square wave isolated by the transformer to analog quantity; Output analog quantity.

[0013] Furthermore, the analog quantity is input, including: Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

[0014] The present invention provides a transformer-based analog quantity isolation transmission device and method, the device includes an analog quantity input module, a symmetrical square wave conversion module, a transformer module, a rectifier module and an analog quantity output module, the analog quantity input module is connected to the symmetrical square wave conversion module, the symmetrical square wave conversion module is connected to the primary side of the transformer module, the rectifier module is connected to the secondary side of the transformer module, and the analog quantity output module is connected to the rectifier module; the analog quantity input module is used to input analog quantity; the symmetrical square wave conversion module is used to convert the input analog quantity into a symmetrical AC square wave; the transformer module is used to transfer the converted AC square wave from the primary side of the transformer to the secondary side of the transformer, and the analog quantity is isolated by the transformer; the rectifier module is used to rectify the AC square wave isolated by the transformer to realize analog quantity restoration; the analog quantity output module is used to output the analog quantity. The present invention can realize the transmission of analog quantity directly based on the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A structural diagram of a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Figure 2 A voltage waveform of a slowly changing analog quantity in a transformer-based analog quantity isolation and transmission device provided by one embodiment of the present invention; Figure 3 A change in a voltage signal of an analog quantity on a smaller time scale in a transformer-based analog quantity isolation transmission device provided by an embodiment of the present invention; Figure 4 A symmetrical AC square wave converted in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Figure 5 A specific implementation principle diagram of a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Figure 6 A first state diagram of a full-bridge converter circuit in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Figure 7 A second state diagram of a full-bridge converter circuit in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Figure 8 A circuit diagram of a half-bridge converter in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Fig. 9 A first state diagram of a push-pull converter circuit in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Fig.10A second state diagram of a push-pull converter circuit in a transformer-based analog quantity isolation transmission device provided by one embodiment of the present invention; Fig.11 An absolute value circuit diagram of an analog quantity isolation transmission device based on a transformer provided by one embodiment of the present invention; Fig.12 An exemplary circuit diagram of a transformer-based analog quantity isolation and transmission device provided for one embodiment of the present invention.

[0016] Description of reference numerals: 100, analog input module; 200, symmetrical square wave conversion module; 300, transformer module; 400, rectifier module; 500, analog output module. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present invention better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present invention are not shown or described in the specification, this is to avoid the core part of the present invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0018] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0019] The first embodiment of the present invention provides a transformer-based analog quantity isolation transmission device, such as Figure 1 As shown, the device includes an analog input module 100, a symmetrical square wave transformation module 200, a transformer module 300, a rectifier module 400 and an analog output module 500, the analog input module 100 is connected to the symmetrical square wave transformation module 200, the symmetrical square wave transformation module 200 is connected to the primary side of the transformer module 300, the rectifier module 400 is connected to the secondary side of the transformer module 300, and the analog output module 500 is connected to the rectifier module 400.

[0020] The analog quantity input module 100 is used to input analog quantity; the symmetrical square wave conversion module 200 is used to convert the input analog quantity into a symmetrical AC square wave; the transformer module 300 is used to transfer the converted AC square wave from the primary of the transformer to the secondary of the transformer, and realize the isolation of the analog quantity through the transformer; the rectifier module 400 is used to rectify the AC square wave isolated by the transformer to realize the restoration of the analog quantity; the analog quantity output module 500 is used to output the analog quantity.

[0021] In this embodiment, the analog quantity input module 100 is specifically used to input a unipolar analog quantity or convert a bipolar analog quantity into a unipolar quantity before inputting. The analog quantity output module 500 is specifically used to directly output a unipolar analog quantity or restore it to a bipolar quantity before outputting. The present invention proposes a new use of a transformer, namely, directly isolating and transmitting an analog quantity through a transformer, and this analog quantity refers to a unipolar analog quantity. If it is a bipolar analog quantity, it is necessary to first convert it into a unipolar analog quantity, and then convert it back to a bipolar analog quantity according to certain methods and rules after isolation, rectification and filtering by a transformer. The bipolar analog quantity here does not refer to an alternating current analog quantity, but refers to a changing analog quantity but may have a negative voltage at a certain time period. The negative polarity can be eliminated by, but not limited to, adding a fixed voltage to this analog quantity.

[0022] The present invention proposes a new use of transformers, that is, directly isolating and transmitting analog quantities through transformers. First, it is assumed that the analog quantity changes relatively slowly, such as Figure 2 The waveform of the voltage is constant within a shorter time frame. Figure 3 Such a signal is difficult to isolate through a transformer because this DC signal will saturate the transformer. The method of isolating analog signals through a transformer without saturating the transformer is to convert the analog signals into Figure 4 The positive and negative symmetrical AC square wave shown in the figure generally does not contain a DC component, and the amplitude of this AC square wave is in a fixed ratio with the amplitude of the analog quantity. The simplest modulation method is a 1:1 ratio, or it can be 1:2, 1:1.5, 1:0.7, or any other known and fixed ratio. The square wave is not only periodic on the time axis, but also symmetrical on the y-axis, i.e., the voltage axis. Such a waveform can be used to transmit the analog quantity V from the primary of the transformer to the secondary of the transformer through a transformer, thereby achieving analog quantity isolation. V is Figure 3 and Figure 4 The voltage amplitude on the y-axis (the input voltage V and the modulated positive and negative amplitude voltage V are the same as a special case, they can also be different, but they must be in a fixed and known ratio). Then the original voltage is restored through synchronous rectification or other rectification circuits or other circuits Figure 2 and Figure 3 The analog quantity shown here, the so-called "restore" here does not necessarily mean that the amplitude must be the same, it can also be different, but it must be in a fixed ratio. "Restore" mainly means to restore Figure 4 The AC voltage shown is converted into DC voltage. The DC voltage must be proportional to the amplitude of the AC voltage. The principle block diagram is as follows Figure 5 shown.

[0023] In this embodiment, the symmetrical square wave conversion module 200 includes a full-bridge converter, a half-bridge converter or a push-pull converter, etc. The so-called analog quantity to symmetrical square wave converter (hereinafter referred to as the converter) can be implemented by a "full-bridge converter" as follows: Figure 6 and Figure 7 As shown, and the "half-bridge converter" is implemented as Figure 8 As shown, a push-pull circuit can also be used as Fig. 9 and Fig.10 These so-called "full-bridge converters", "half-bridge converters" and "push-pull converters" are all concepts of switching power supply topologies in power electronics. These concepts are just borrowed here, and the working principles are very similar.

[0024] by Figure 6 and Figure 7 Take the full bridge circuit as an example, Figure 6 At the beginning, K1 and K4 are turned on at the same time, while K2 and K3 are turned off at the same time. At this time, the current flows from Vi through K1 through the primary of the transformer (the direction of the arrow represents the flow direction of the primary current of the transformer), then flows through the capacitor through K4 to GND. This is the first half cycle. The second half cycle is as follows Figure 7 As shown, the current flows from Vi through K3, through the capacitor and then to the primary of the transformer (the direction of the arrow represents the flow direction of the primary current of the transformer), and then K2 flows to GND, and then repeats continuously, maintaining a fixed frequency and period, so that Figure 3 The analog quantity becomes Figure 4 The secondary of the transformer also gets almost the same Figure 4 The so-called "full-bridge converter", "half-bridge converter" and "push-pull converter" are only used to illustrate how to convert a unipolar analog quantity into a symmetrical converter with a fixed ratio to the input analog quantity amplitude. Figure 4 The AC shown can also be other circuits of various forms, as long as it can achieve Figure 3 The analog quantity shown becomes Figure 4 Same functionality as shown in AC. Figure 8 The half-bridge circuit is very similar to the full-bridge circuit, except that two capacitors are used instead of the two switches of one bridge arm. When the two capacitors are large enough, the voltage at the middle point of the two capacitors remains basically unchanged, and functions similar to those of the full-bridge circuit can also be achieved.

[0025] like Fig. 9and Fig.10 The push-pull circuit shown is another example. Fig. 9 When S1 is turned on, S2 is turned off, and the current flows from Vi through the upper half of the transformer primary (direction is as follows Fig. 9 As shown), through S1 to GND, this is the upper half cycle, the lower half cycle flows from Vi through the lower half of the primary of the transformer (direction as Fig.10 As shown), and then connected to GND through S2, so that the two primary windings of the transformer work separately, and the Figure 3 The analog quantity shown becomes Figure 4 As shown in the figure, the secondary of the transformer also gets almost the same Figure 4 Same AC signal.

[0026] The so-called "full-bridge converter", "half-bridge converter" and "push-pull converter" in this embodiment are very similar to the "full-bridge converter", "half-bridge converter" and "push-pull converter" in the switching power supply circuit. The difference is that these "full-bridge converter", "half-bridge converter" and "push-pull converter" in the switching power supply are used to transfer energy, while the "full-bridge converter", "half-bridge converter" and "push-pull converter" here are used to transfer "analog signals", and these "full-bridge converter", "half-bridge converter" and "push-pull converter" are only some examples, and can also be any other symmetrical converter that can convert a unipolar analog quantity into a fixed proportion to the input analog quantity amplitude, such as Figure 4 AC shown. Figure 6 and Figure 7 , Figure 8 as well as Fig. 9 and Fig.10 The different switching states of switch S change the direction of the transformer primary current (the direction of the arrow next to the transformer primary in the figure). The change in the direction of the transformer primary current completes the conversion from a unipolar analog quantity to a symmetrical one with a fixed ratio to the input analog quantity amplitude. Figure 4 AC shown.

[0027] In this embodiment, the rectifier module 400 includes: a rectifier circuit including a diode, a synchronous rectifier circuit including a controllable switch, a voltage doubler rectifier circuit including a diode and a controllable switch, or an absolute value circuit including an operational amplifier. Specifically, Figure 6 and Figure 7 , Figure 8 as well as Fig. 9 and Fig.10 The rectifier circuit in the embodiment may be a rectifier circuit composed of a diode, or a synchronous rectifier circuit composed of a controllable switch such as a triode or an analog switch, and may be, but not limited to, a voltage doubling rectifier circuit composed of a diode and a controllable switch, and an absolute value circuit composed of an operational amplifier, wherein the absolute value circuit may be Fig.11The analog quantity is converted into an AC square wave, isolated by a transformer, and then restored to an analog quantity through an absolute value circuit, thereby achieving analog quantity isolation.

[0028] The following is an example of using analog switches, operational amplifiers, oscillators, and isolation transformers to implement an analog isolation for gate drive control of a high-voltage amplifier. Fig.12 As shown. In this example, the symmetrical square wave conversion module 200 includes an oscillator, a switch S, an operational amplifier U1, a resistor R1 and a resistor R2; the first fixed end of the switch S is connected to the analog input end, the second fixed end of the switch S is connected to the GND end, the positive input end of the operational amplifier U1 is connected to the moving end of the switch S, the output of the oscillator drives the moving end of the switch S to switch back and forth between the first fixed end and the second fixed end, the output end of the operational amplifier U1 is connected to the primary of the transformer, the first end of the resistor R2 is connected to the node between the analog input end and the first fixed end of the switch S, the second end of the resistor R2 is connected to the negative input end of the operational amplifier U1, the first end of the resistor R1 is connected to the node between the resistor R2 and the negative input end of the operational amplifier U1, and the second end of the resistor R1 is connected to the output end of the operational amplifier U1. In this embodiment, the symmetrical square wave conversion module 200 also includes a capacitor C, which is connected in series between the output end of the operational amplifier U1 and the primary of the transformer, and the second end of the resistor R1 is connected to the node between the output end of the operational amplifier U1 and the capacitor C.

[0029] Fig.12The oscillator generates a higher frequency oscillation signal. The output of the oscillator drives the switch S (which can be a semiconductor switch such as a transistor or an analog switch) to periodically switch the 3-terminal connected to the positive input of the operational amplifier back and forth between 1 and 2. When the 3-terminal is connected to the 1-terminal, R1, R2, the switch S and the operational amplifier U1 form a follower (the presence or absence of R2 here will not affect the function of the follower), and the input and output are equal. When the 3-terminal and the 2-terminal are connected, R1, R2, the switch S and the operational amplifier are connected to form an inverting amplifier, and the output and input of the operational amplifier U1 are opposite. The role of R1 is to serve as the feedback resistor of the operational amplifier U1. R2 is the input resistor of the inverting amplifier, connected from the signal input to the inverting input of the operational amplifier U1. As a result, a square wave signal with the same amplitude as the input (assuming V volts) and symmetrical between +V and -V is obtained at the input of the transformer. After this square wave signal is isolated by the transformer, a corresponding signal proportional to the turns ratio is obtained at the secondary of the transformer. The function of capacitor C is to prevent magnetic bias from causing transformer saturation. Of course, other methods can be used to avoid magnetic bias, such as but not limited to connecting a resistor in series or a field effect transistor (MosFET) in series or a reverse parallel diode in series. Assuming that the turns ratio of the transformer is 1:1, the secondary signal and the primary signal of the transformer will be exactly the same. After rectification by the rectifier circuit and appropriate filtering, the original analog quantity is restored. The turns ratio of the transformer can also be other than 1:1, and can be any other reasonable ratio, such as 2:1. Through the 2x voltage rectification after the secondary of the transformer, the final 1:1 can be achieved. Even if the final ratio is not 1:1, but 1:2 (or other possible reasonable ratios), it is equivalent to amplifying the signal by 2 times, and the isolation of the analog quantity is also achieved. It can also be more suitable for certain applications, such as being used for isolation amplifiers as the input of subsequent amplifiers.

[0030] A second embodiment of the present invention provides a transformer-based analog quantity transmission method, the method comprising: S100, input analog quantity; S200, converts the input analog quantity into a symmetrical AC square wave; S300 transfers the transformed AC square wave from the primary of the transformer to the secondary of the transformer, and isolates the analog quantity through the transformer; S400, restores the AC square wave isolated by the transformer to analog quantity; S500, output analog quantity.

[0031] Furthermore, the analog quantity is input, including: Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

[0032] It should be noted that, for a detailed description of a transformer-based analog quantity transmission method provided in an embodiment of the present invention, reference can be made to the relevant description of a transformer-based analog quantity transmission method and device provided in an embodiment of the present invention, which will not be repeated here.

[0033] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A transformer-based analog quantity isolation transmission device, characterized in that: The device comprises an analog quantity input module, a symmetrical square wave conversion module, a transformer module, a rectifier module and an analog quantity output module, wherein the analog quantity input module is connected to the symmetrical square wave conversion module, the symmetrical square wave conversion module is connected to the primary side of the transformer module, the rectifier module is connected to the secondary side of the transformer module, and the analog quantity output module is connected to the rectifier module; Analog input module, used to input analog quantity; Symmetrical square wave conversion module, used to convert the input analog quantity into a symmetrical AC square wave; The transformer module is used to transfer the transformed AC square wave from the primary side of the transformer to the secondary side of the transformer, and to achieve the isolation of the analog quantity through the transformer; The rectifier module is used to rectify the AC square wave isolated by the transformer to restore the analog quantity; Analog output module, used to output analog quantity.

2. The transformer-based analog quantity isolation transmission device according to claim 1, characterized in that: The symmetrical square wave conversion module is specifically used to convert the input analog quantity into a symmetrical AC square wave whose voltage amplitude is in a preset ratio with the voltage amplitude of the input analog quantity.

3. The transformer-based analog quantity isolation transmission device according to claim 1, characterized in that: The symmetrical square wave conversion module includes a full-bridge converter, a half-bridge converter or a push-pull converter.

4. The transformer-based analog quantity isolation transmission device according to claim 1, characterized in that: The rectification module includes: a rectification circuit including a diode, a synchronous rectification circuit including a controllable switch, a voltage doubling rectification circuit including a diode and a controllable switch, or an absolute value circuit including an operational amplifier.

5. The transformer-based analog quantity isolation transmission device according to claim 1, characterized in that: The analog quantity input module is specifically used for inputting unipolar analog quantities or converting bipolar analog quantities into unipolar quantities before inputting.

6. The transformer-based analog quantity isolation transmission device according to claim 5, characterized in that: The analog output module is specifically used to directly output a unipolar analog quantity or to restore it to a bipolar value before outputting it.

7. The transformer-based analog quantity isolation and transmission device according to claim 1, characterized in that: The symmetrical square wave conversion module includes an oscillator, a switch S, an operational amplifier U1, a resistor R1 and a resistor R2; A first fixed end of the switch S is connected to the analog input end, a second fixed end of the switch S is connected to the GND end, a positive input end of the operational amplifier U1 is connected to the moving end of the switch S, an output of the oscillator drives the moving end of the switch S to switch back and forth between the first fixed end and the second fixed end, an output end of the operational amplifier U1 is connected to the primary of the transformer, a first end of the resistor R2 is connected to a node between the analog input end and the first fixed end of the switch S, a second end of the resistor R2 is connected to the negative input end of the operational amplifier U1, a first end of the resistor R1 is connected to a node between the resistor R2 and the negative input end of the operational amplifier U1, and a second end of the resistor R1 is connected to the output end of the operational amplifier U1.

8. The transformer-based analog quantity isolation and transmission device according to claim 7, characterized in that: The symmetrical square wave conversion module further includes a capacitor C, which is connected in series between the output end of the operational amplifier U1 and the primary of the transformer. The second end of the resistor R1 is connected to a node between the output end of the operational amplifier U1 and the capacitor C.

9. A transformer-based analog quantity isolation method, characterized in that: The method comprises: Input analog quantity; Convert the input analog quantity into a symmetrical AC square wave; The transformed AC square wave is transferred from the primary of the transformer to the secondary of the transformer, and the analog quantity is isolated through the transformer; Restore the AC square wave isolated by the transformer to analog quantity; Output analog quantity.

10. The transformer-based analog quantity transmission method according to claim 9, characterized in that: Input analog quantity, including: Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

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