Transformer-based analog quantity isolation transmission device and method

Abstract

The present invention discloses a transformer-based analog quantity isolation and transmission device and method, 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 used to input an 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 of the transformer to the secondary of the transformer, thereby isolating 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; and the analog quantity output module is used to output the analog quantity. The present invention can realize direct analog quantity transmission 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 and 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 two isolated circuits. This invention proposes a new use for transformers, namely, the isolated transmission of analog signals using transformers. Summary of the Invention

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

[0004] A first embodiment of the present invention provides a transformer-based analog isolation and transmission device, comprising an analog input module, a symmetrical square wave conversion module, a transformer module, a rectifier module, and an analog output module, wherein the analog 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 output module is connected to the rectifier module.

[0005] Analog input module, used to input analog quantity;

[0006] Symmetrical square wave conversion module, used to convert the input analog quantity into a symmetrical AC square wave;

[0007] The transformer module is used to transfer the transformed AC square wave from the primary to the secondary of the transformer, and to achieve analog isolation through the transformer;

[0008] The rectifier module is used to rectify the AC square wave isolated by the transformer to restore the analog value;

[0009] Analog output module, used to output analog quantities.

[0010] 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.

[0011] Furthermore, the symmetrical square wave conversion module includes a full-bridge converter, a half-bridge converter or a push-pull converter.

[0012] Furthermore, the rectification module includes: a rectification circuit including a diode, a synchronous rectification circuit including a controllable switch, a voltage doubler rectification circuit including a diode and a controllable switch, or an absolute value circuit including an operational amplifier.

[0013] Furthermore, the analog input module is specifically used to input unipolar analog quantities or convert bipolar analog quantities into unipolar quantities before inputting them.

[0014] Furthermore, the analog output module is specifically used to directly output a unipolar analog quantity or to restore it to bipolarity before outputting it.

[0015] Furthermore, the symmetrical square wave conversion module includes an oscillator, a switch S, an operational amplifier U1, a resistor R1 and a resistor R2;

[0016] 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, and 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.

[0017] 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.

[0018] A second embodiment of the present invention provides a transformer-based analog quantity isolation and transmission method, the method comprising:

[0019] Input analog quantity;

[0020] Convert the input analog quantity into a symmetrical AC square wave;

[0021] The transformed AC square wave is transferred from the primary side of the transformer to the secondary side of the transformer, and the analog quantity is isolated through the transformer;

[0022] Restore the analog value of AC square wave isolated by transformer;

[0023] Output analog quantity.

[0024] Furthermore, the analog quantity is input, specifically including:

[0025] Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

[0026] The present invention provides a transformer-based analog quantity isolation and 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 an 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, thereby isolating 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. The analog quantity output module is used to output the analog quantity. The present invention can realize direct analog quantity transmission based on the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A structural diagram of a transformer-based analog quantity isolation and transmission device provided in one embodiment of the present invention;

[0028] Figure 2 A slowly changing voltage waveform of an analog quantity in a transformer-based analog quantity isolation and transmission device provided by one embodiment of the present invention;

[0029] Figure 3 A transformer-based analog quantity isolation and transmission device according to one embodiment of the present invention provides a change in a voltage signal of an analog quantity on a smaller time scale;

[0030] Figure 4 A symmetrical AC square wave converted in a transformer-based analog quantity isolation and transmission device provided by one embodiment of the present invention;

[0031] Figure 5 A specific implementation principle diagram of a transformer-based analog quantity isolation and transmission device provided by one embodiment of the present invention;

[0032] Figure 6 A first state diagram of a full-bridge converter circuit in a transformer-based analog isolation and transmission device provided by one embodiment of the present invention;

[0033] Figure 7 A second state diagram of a full-bridge converter circuit in a transformer-based analog isolation and transmission device provided by one embodiment of the present invention;

[0034] Figure 8 A circuit diagram of a half-bridge converter in a transformer-based analog isolation and transmission device provided in one embodiment of the present invention;

[0035] Figure 9 A first state diagram of a push-pull converter circuit in a transformer-based analog isolation and transmission device provided by one embodiment of the present invention;

[0036] Figure 10 A second state diagram of a push-pull converter circuit in a transformer-based analog quantity isolation and transmission device provided by one embodiment of the present invention;

[0037] Figure 11 An absolute value circuit diagram of a transformer-based analog quantity isolation and transmission device provided in one embodiment of the present invention;

[0038] Figure 12 An exemplary circuit diagram of a transformer-based analog isolation and transmission device provided in accordance with an embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 100, analog input module; 200, symmetrical square wave conversion module; 300, transformer module; 400, rectifier module; 500, analog output module. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present invention to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted under different circumstances, or may be replaced by other elements, materials, or 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 of the present invention being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0042] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0043] The first embodiment of the present invention provides an analog quantity isolation transmission device based on a transformer, such as Figure 1As shown, the device includes an analog input module 100, a symmetrical square wave conversion 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 conversion module 200, the symmetrical square wave conversion 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.

[0044] The analog input module 100 is used to input analog quantities; the symmetrical square wave conversion module 200 is used to convert the input analog quantities into symmetrical AC square waves; the transformer module 300 is used to transfer the converted AC square waves from the primary of the transformer to the secondary of the transformer, thereby isolating the analog quantities through the transformer; the rectifier module 400 is used to rectify the AC square waves isolated by the transformer to restore the analog quantities; and the analog output module 500 is used to output analog quantities.

[0045] In this embodiment, the analog input module 100 is specifically used to input a unipolar analog quantity or convert a bipolar analog quantity into a unipolar one before inputting it. The analog output module 500 is specifically used to directly output a unipolar analog quantity or restore it to a bipolar one before outputting it. The present invention proposes a new use of the transformer, namely, directly isolating and transmitting analog quantities through a transformer, and this analog quantity refers to a unipolar analog quantity. If it is a bipolar analog quantity, it needs to be converted into a unipolar analog quantity first, and then converted 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 AC analog quantity, but refers to a changing analog quantity that 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.

[0046] The present invention proposes a new use of transformers, that is, to directly isolate and transmit analog quantities through transformers. First, it is assumed that the analog quantity changes relatively slowly, such as Figure 2 Therefore, it is considered that the voltage is constant in a shorter time range, such as 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 4The 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, but it can also 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, that is, 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 amplitude of the voltage 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 AC amplitude. The principle block diagram is as follows Figure 5 shown.

[0047] In this embodiment, the symmetrical square wave conversion module 200 includes a full-bridge converter, a half-bridge converter, or a push-pull converter. The so-called analog-to-symmetrical square wave converter (hereinafter referred to as the converter) can be implemented as a "full-bridge converter". 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 Figure 9 and Figure 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.

[0048] 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 4The secondary side of the transformer also gets almost the same Figure 4 The so-called "full-bridge converter", "half-bridge converter" and "push-pull converter" are just examples of converting unipolar analog signals into symmetrical signals with a fixed ratio to the input analog signal amplitude. Figure 4 The AC shown can also be other forms of circuits, as long as it can achieve Figure 3 The analog quantity shown becomes Figure 4 Same functionality as shown in the 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 a full-bridge circuit can also be achieved.

[0049] like Figure 9 and Figure 10 The push-pull circuit shown is another example. Figure 9 When S1 is turned on and S2 is turned off, the current flows from Vi through the upper half of the transformer primary (direction as shown in Figure 9 As shown), through S1 to GND, this is the first half cycle, the second half cycle flows from Vi through the lower half of the primary of the transformer (direction as Figure 10 As shown), then connect 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 AC, the secondary side of the transformer also gets almost the same Figure 4 Same AC signal.

[0050] 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 just some examples, and can also be any other symmetrical converter that can convert unipolar analog quantities 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 Figure 9 and Figure 10The 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.

[0051] 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 Figure 9 and Figure 10 The rectifier circuit in the embodiment can be a rectifier circuit composed of diodes, or a synchronous rectifier circuit composed of a controllable switch such as a triode or an analog switch, and can be, but not limited to, a voltage doubler 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 is as follows: Figure 11 The 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, thus achieving analog quantity isolation.

[0052] The following is an example of using analog switches, operational amplifiers, oscillators, and isolation transformers to implement analog isolation for gate drive control of high-voltage amplifiers. Figure 12 As shown. In this example, the symmetrical square wave conversion module 200 includes an oscillator, a switch S, an op amp 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 op amp 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 op amp 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 op amp U1, the first end of the resistor R1 is connected to the node between the resistor R2 and the negative input end of the op amp U1, and the second end of the resistor R1 is connected to the output end of the op amp 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 op amp U1 and the primary end of the transformer, and the second end of the resistor R1 is connected to the node between the output end of the op amp U1 and the capacitor C.

[0053] Figure 12The oscillator generates a high-frequency oscillating signal. The oscillator's output drives switch S (which can be a semiconductor switch such as a transistor or analog switch), which periodically switches the op amp's positive input terminal, terminal 3, back and forth between terminals 1 and 2. When terminal 3 connects to terminal 1, R1, R2, switch S, and op amp U1 form a follower circuit (the presence or absence of R2 does not affect the follower's function). In this case, the input and output are equal. When terminals 3 and 2 connect, R1, R2, switch S, and the op amp form an inverting amplifier, with the output and input of op amp U1 opposite. R1 acts as the feedback resistor for op amp U1. R2, the input resistor of the inverting amplifier, connects from the signal input to the inverting input of op amp U1. This generates a square wave signal at the transformer input with the same amplitude as the input (assuming V volts) and symmetrical between +V and -V. This square wave signal is isolated by the transformer, and a corresponding signal proportional to the turns ratio is generated at the transformer's secondary. Capacitor C prevents magnetic bias from saturating the transformer. Other methods can be used to prevent magnetic bias, such as, but not limited to, a series resistor, a field-effect transistor (MOSFET), or an anti-parallel diode. Assuming a transformer turns ratio of 1:1, the secondary and primary signals are identical. After rectification and appropriate filtering, the original analog value is restored. The transformer's turns ratio can also be anything other than 1:1, such as 2:1. A double-voltage rectification after the transformer's secondary can achieve a final 1:1 ratio. Even if the final ratio is 1:2 (or any other reasonable ratio), the signal is amplified by a factor of two, achieving analog isolation and making it more suitable for certain applications, such as using it as the input of an isolation amplifier.

[0054] A second embodiment of the present invention provides a transformer-based analog quantity transmission method, the method comprising:

[0055] S100, analog input;

[0056] S200 converts the input analog quantity into a symmetrical AC square wave;

[0057] S300 transmits the transformed AC square wave from the primary to the secondary of the transformer, achieving analog isolation through the transformer;

[0058] S400, converts the AC square wave isolated by the transformer into analog value;

[0059] S500, output analog quantity.

[0060] Furthermore, the analog quantity is input, specifically including:

[0061] Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

[0062] 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 apparatus provided in an embodiment of the present invention, which will not be repeated here.

[0063] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A transformer-based analog isolation and transmission device, characterized in that: The device includes an analog input module, a symmetrical square wave conversion module, a transformer module, a rectifier module and an analog output module; The analog 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 output module is connected to the rectifier module; The symmetrical square wave conversion module includes an oscillator, a switch S, an operational amplifier U1, a resistor R1, a resistor R2, and a capacitor C; a first fixed end of the switch S is connected to the analog input end, a second fixed end 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, and 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 through the capacitor C, 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, and a second end 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 is connected to a node between the output end of the operational amplifier U1 and the capacitor C; The transformer module is used to transfer the transformed AC square wave from the primary to the secondary of the transformer, and to achieve analog isolation through the transformer; The rectifier module is used to rectify the AC square wave isolated by the transformer to restore the analog value; Analog output module, used to output analog quantity; 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.

2. The transformer-based analog quantity isolation and transmission device according to claim 1, characterized in that: The rectifier module 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.

3. The transformer-based analog quantity isolation and 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 them.

4. The transformer-based analog quantity isolation and transmission device according to claim 3, characterized in that: The analog output module is specifically used to directly output a unipolar analog quantity or to restore it to bipolarity before outputting it.

5. A transformer-based analog isolation method, characterized in that: The transformer-based analog quantity isolation and transmission device used in any one of claims 1 to 4, wherein 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 side of the transformer to the secondary side of the transformer, and the analog quantity is isolated through the transformer; Restore the analog value of AC square wave isolated by transformer; Output analog quantity; The input analog quantity specifically includes: Input unipolar analog quantity or convert bipolar analog quantity into unipolar quantity before inputting.

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