A signal processing circuit based on transformer isolation

Abstract

The present application discloses a signal processing circuit based on transformer isolation, comprising: the signal modulation module is used to modulate the input signal to obtain a modulated signal; the isolation transformer is used to transmit the modulated signal to the signal demodulation module; the signal demodulation module is used to demodulate the modulated signal to obtain a restored input signal. The modulation and demodulation principle of the present invention is simple and easy to implement, and the signal transmission frequency is not limited by the original signal.

Description

Technical Field

[0001] The present application relates to the technical field of signal processing, and in particular to a signal processing circuit based on transformer isolation. Background Art

[0002] In the field of power electronics, signal transmission control is indispensable. For safety and signal noise reduction considerations, signals need to be isolated and transmitted. The main purpose of signal isolation is to prevent high-voltage circuits from interfering with and damaging low-voltage control circuits, thereby ensuring stable and reliable operation of the system. Transformers are widely used in various power electronic devices due to their reliable isolation performance and noise reduction effects. However, DC signals cannot be transmitted through transformers without modulation. In addition, when the frequency of the transmitted signal is low, the size of the transformer will increase, which will increase the overall weight and cost of the system. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present application provides a signal processing circuit based on transformer isolation, which is used to solve at least one defect in the prior art.

[0004] To achieve the above objectives and other objectives, the present application provides a signal processing circuit based on transformer isolation, the circuit comprising: a signal modulation module, an isolation transformer and a signal demodulation module;

[0005] The signal modulation module is used to modulate the input signal to obtain a modulated signal; the isolation transformer is used to transmit the modulated signal to the signal demodulation module; the signal demodulation module is used to demodulate the modulated signal to obtain a restored input signal.

[0006] In one embodiment of the present invention, the signal modulation module includes: a signal modulation unit, a level shift unit and an output unit;

[0007] The signal modulation unit is used to modulate the input signal; the level shift unit is used to perform level conversion on the modulated input signal; and the output unit is used to amplify the input signal after level conversion to obtain the modulated signal.

[0008] In one embodiment of the present invention, the output unit includes: a first MOS tube and a second MOS tube; the gate of the first MOS tube is connected to the output end of the level shift unit, and the source of the first MOS tube is connected to the power supply voltage; the gate of the second MOS tube is connected to the output end of the level shift unit, the source of the second MOS tube is grounded, and the drain of the second MOS tube is connected to the drain of the first MOS tube to form an electrical node, and the electrical node is connected to the input end of the isolation transformer.

[0009] In one embodiment of the present invention, the output unit further includes a first amplifier and a second amplifier, the input end of the first amplifier is connected to the output end of the level shift unit, and the output end of the first amplifier is connected to the gate of the first MOS tube; the input end of the second amplifier is connected to the output end of the level shift unit, and the output end of the second amplifier is connected to the gate of the second MOS tube.

[0010] In one embodiment of the present invention, the input signal is a square wave signal. When the signal modulation module modulates the square wave signal, it first generates high and low level narrow pulse signals with a width of T1, respectively marking the rising edge and falling edge of the input signal, and then generates a high-frequency square wave signal with a period of T2, respectively marking the high level and low level of the input signal.

[0011] In one embodiment of the present invention, when the square wave signal jumps from a low level to a high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1 to mark the rising edge of the square wave signal, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the square wave signal;

[0012] When the square wave signal changes from a high level to a low level, the signal modulation module first generates a low-level narrow pulse signal with a width of T1 to mark the falling edge of the original signal, and then generates a high-frequency square wave signal with a period of T2 to mark the low level of the square wave signal.

[0013] In one embodiment of the present invention, the input signal is a DC signal. When the signal modulation module modulates the DC signal, it first generates a low and high level narrow pulse signal with a width of T1, and then generates a high frequency square wave signal with a period of T2 to mark the low and high levels of the DC signal.

[0014] In one embodiment of the present invention, when the DC signal is a DC low level, the signal modulation module first generates a low level narrow pulse signal with a width of T1, and then generates a high frequency square wave signal with a period of T2 to mark the low level of the DC signal;

[0015] When the DC signal is at a high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the DC signal.

[0016] In one embodiment of the present invention, the circuit further includes a capacitor connected in series between the primary coil of the isolation transformer and the signal modulation module.

[0017] In one embodiment of the present invention, the circuit further includes a diode connected in series between the secondary coil of the isolation transformer and the signal demodulation module.

[0018] Beneficial effects of this application:

[0019] The present invention discloses a signal processing circuit based on transformer isolation, comprising: the signal modulation module is used to modulate the input signal to obtain a modulated signal; the isolation transformer is used to transmit the modulated signal to the signal demodulation module; the signal demodulation module is used to demodulate the modulated signal to obtain a restored input signal. The modulation and demodulation principle of the present invention is simple and easy to implement, and the signal transmission frequency is not limited by the original signal.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0022] Figure 1 This is a principle block diagram of a signal processing circuit based on transformer isolation according to an embodiment of the present application;

[0023] Figure 2a A timing diagram of input signals IN1 and IN2 and output signals OUT1 and OUT2 according to an embodiment of the present application; Figure 2b This is a timing diagram of input signals IN1 and IN2, and output signals OUT1 and OUT2 when the input signal of the embodiment of the present application is a square wave signal; Figure 2c 1 is a timing diagram of input signals IN1 and IN2 and output signals OUT1 and OUT2 when the input signal of the embodiment of the present application is a DC signal. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0026] Although the terms "first", "second", "A", and "B", etc. may be used herein to describe various elements, these elements should not be limited by these terms and are only used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the following technology. The term "and / or" includes a combination of multiple related items or any of the multiple related items.

[0027] As used herein, unless the context indicates otherwise, the singular form is intended to include the plural form, and it will be understood that the term "comprising" means the presence of stated features, quantities, steps, operations, elements, or combinations thereof, but does not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof.

[0028] Before the detailed description, it is intended to clarify that the division of components in this specification is divided only by the main function of each component. That is, two or more components to be described below can be combined into one component, or can be divided into two or more components according to more detailed functions. In addition to the main function of the component, each component to be described below can also perform some or all of the functions of other components, and some of the main functions of each component can be exclusively performed by other components.

[0029] In the field of power electronics, signal transmission control is indispensable. For safety and signal noise reduction considerations, signals need to be isolated and transmitted. The main purpose of signal isolation is to prevent high-voltage circuits from interfering with and damaging low-voltage control circuits, thereby ensuring stable and reliable operation of the system. Common isolation schemes are: 1) Using digital isolation chips to power the primary and secondary sides through isolated power supplies to achieve signal isolation transmission, but digital isolation chips are usually expensive, which limits the application scenarios; 2) Using optical coupler isolation chips, which have strong anti-interference capabilities, but this type of chip has a limited service life and is greatly affected by temperature; 3) Using optical fiber isolation transmission, the transmission distance is long, but the transmission delay is large and the cost is also high; 4) Transformer isolation, transformers are widely used in various power electronic equipment due to their reliable isolation performance and noise reduction effects. However, DC signals cannot be transmitted through transformers without modulation. In addition, when the frequency of the transmitted signal is low, the volume of the transformer will increase, which will lead to an increase in the overall weight and cost of the system. This is because low-frequency signals require larger cores and more winding turns to maintain sufficient magnetic flux, thereby maintaining good transmission performance.

[0030] In order to overcome the limitations of transformers in low-frequency and DC signal transmission, modulation technology is usually used. By modulating the DC signal or low-frequency signal onto a high-frequency carrier, transmitting it through a transformer, and finally demodulating it at the receiving end, effective isolation and transmission of DC and low-frequency signals can be achieved. This method not only improves transmission efficiency, but also reduces the size and weight of the transformer.

[0031] See also Figure 1 , Figure 1 This is a principle block diagram of a signal processing circuit based on transformer isolation according to an embodiment of the present application. Figure 1 As shown, the signal processing circuit based on transformer isolation includes: a signal modulation module, an isolation transformer and a signal demodulation module;

[0032] The signal modulation module is used to modulate the input signal to obtain a modulated signal; the isolation transformer is used to transmit the modulated signal to the signal demodulation module; the signal demodulation module is used to demodulate the modulated signal to obtain a restored input signal.

[0033] like Figure 1 As shown, the input signal is modulated by the signal modulation module ASIC1, and after being transmitted through the isolation transformer T, it is demodulated by the signal demodulation module ASIC2 to restore the original signal.

[0034] The present invention modulates the input signal into a high-frequency square wave signal, transmits it through a transformer, and then demodulates it through a low-pass filter to restore it to the original DC signal or low-frequency square wave signal. Through this method, the transmission of DC signals and square wave signals of any frequency can be realized, and while achieving good signal isolation, the volume of the transformer and the complexity of the modulation and demodulation circuit are greatly reduced, thereby reducing the cost. It should be noted that the input signal is a DC signal or a low-frequency square wave signal.

[0035] In the embodiment of the present application, the signal modulation module includes: a signal modulation unit, a level shift unit and an output unit;

[0036] The signal modulation unit is used to modulate the input signal; the level shift unit is used to perform level conversion on the modulated input signal; and the output unit is used to amplify the input signal after level conversion to obtain the modulated signal.

[0037] In an embodiment of the present application, the output unit includes: a first MOS tube and a second MOS tube; the gate of the first MOS tube is connected to the output end of the level shift unit, and the source of the first MOS tube is connected to the power supply voltage; the gate of the second MOS tube is connected to the output end of the level shift unit, the source of the second MOS tube is grounded, and the drain of the second MOS tube is connected to the drain of the first MOS tube to form an electrical node, and the electrical node is connected to the input end of the isolation transformer.

[0038] In an embodiment of the present application, taking into account the situation that the driving capability of the level shift unit may be insufficient, the output unit also includes a first amplifier and a second amplifier, the input end of the first amplifier is connected to the output end of the level shift unit, and the output end of the first amplifier is connected to the gate of the first MOS tube; the input end of the second amplifier is connected to the output end of the level shift unit, and the output end of the second amplifier is connected to the gate of the second MOS tube.

[0039] It should be noted that the signal modulation unit, the level shift unit, the first amplifier, the second amplifier, the first MOS transistor and the second MOS transistor are integrated in the same chip, and the first MOS transistor and the second MOS transistor form a push-pull structure.

[0040] In an embodiment of the present application, the input signal is a square wave signal. When the signal modulation module modulates the square wave signal, it first generates high and low level narrow pulse signals with a width of T1, respectively marking the rising edge and falling edge of the input signal, and then generates a high-frequency square wave signal with a period of T2, respectively marking the high level and low level of the input signal.

[0041] Specifically, when the square wave signal jumps from a low level to a high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1 to mark the rising edge of the square wave signal, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the square wave signal; when the square wave signal jumps from a high level to a low level, the signal modulation module first generates a low-level narrow pulse signal with a width of T1 to mark the falling edge of the original signal, and then generates a high-frequency square wave signal with a period of T2 to mark the low level of the square wave signal.

[0042] For a square wave input signal, when the input signal (IN1) jumps from a low level to a high level, the signal modulation unit in the signal modulation module ASIC1 modulates the input signal (IN1), generates a high-level narrow pulse signal with a width of T1 to mark the rising edge of the input signal. After being isolated and transmitted by the isolation transformer T, the marked input signal (i.e., the output signal OUT1) is restored by the signal demodulation module ASIC2 to the rising edge of the original input signal (OUT2), corresponding to Figure 2a the I stage in; then, a high-frequency square wave signal with a period of T2 is generated to mark the high level of the input signal. After being isolated and transmitted by the isolation transformer T, it is demodulated to the high level of the input signal, where T2 < T1, corresponding to Figure 2a the II stage in; when the input signal jumps from a high level to a low level, the signal modulation unit in the signal modulation module ASIC1 modulates it, generates a low-level narrow pulse signal with a width of T1 to mark the falling edge of the original signal. After being isolated and transmitted by the isolation transformer T, it is demodulated to the falling edge of the original signal, corresponding to Figure 2a the III stage in; finally, a high-frequency square wave signal with a period of T2 is also generated to mark the low level of the input signal. After being isolated and transmitted by the isolation transformer T, it is demodulated to the low level of the input signal, corresponding to Figure 2a the IV stage in.

[0043] In the embodiment of the present application, the input signal is a DC signal. When the signal modulation module modulates the DC signal, it first generates a low-high level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the low-high level of the DC signal.

[0044] Specifically, when the DC signal is a DC low level, the signal modulation module first generates a low-level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the low level of the DC signal; when the DC signal is a DC high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the DC signal.

[0045] For the input signal as a DC signal, when the input signal is a DC low level, the signal modulation unit in the signal modulation module ASIC1 modulates the DC signal (IN1), generates a low-level narrow pulse signal with a width of T1 at the initial moment, and then generates a high-frequency square wave signal with a period of T2, marking the low level of the input signal (OUT1), and after isolation and transmission through the isolation transformer T, obtains the signal IN2, which is demodulated to the low level of the input signal (OUT2), corresponding to Figure 2b When the input signal is a DC high level, the signal modulation unit in the signal modulation module ASIC1 modulates it, generates a high-level narrow pulse signal with a width of T1 at the initial moment, and then generates a high-frequency square wave signal with a period of T2, marking the high level of the input signal, and after isolation and transmission through the isolation transformer T, it is demodulated to the high level of the input signal, corresponding to Figure 2c .

[0046] In the embodiment of the present application, the signal demodulation module ASIC2 counts the pulse width of the modulated signal during demodulation, and starts to output a high level when the high level time length is T1, and starts to output a low level when the next low level time length is T1, and repeats this process to achieve signal demodulation and restore the original signal.

[0047] In an embodiment of the present application, the circuit further includes a capacitor C connected in series between the primary coil of the isolation transformer and the signal modulation module.

[0048] In the embodiment of the present application, the circuit further includes a diode D connected in series between the secondary coil of the isolation transformer and the signal demodulation module.

[0049] The present invention uses high-level and low-level pulse signals to mark the rising edge and falling edge of the original signal respectively, and uses high-frequency square wave signals to mark the DC signal to achieve signal modulation. In addition, high-frequency modulation can also be achieved for DC high-level and low-level signals.

[0050] The above embodiments are merely illustrative of the principles and effects of the present application, and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A signal processing circuit based on transformer isolation, characterized in that: The circuit comprises: a signal modulation module, an isolation transformer and a signal demodulation module; The signal modulation module is used to modulate the input signal to obtain a modulated signal; the isolation transformer is used to transmit the modulated signal to the signal demodulation module; the signal demodulation module is used to demodulate the modulated signal to obtain a restored input signal; The input signal is a square wave signal. When the signal modulation module modulates the square wave signal, it first generates high and low level narrow pulse signals with a width of T1, marking the rising edge and falling edge of the input signal respectively, and then generates a high frequency square wave signal with a period of T2, marking the high level and low level of the input signal respectively.

2. The signal processing circuit based on transformer isolation according to claim 1, characterized in that: The signal modulation module comprises: a signal modulation unit, a level shift unit and an output unit; The signal modulation unit is used to modulate the input signal; the level shift unit is used to perform level conversion on the modulated input signal; and the output unit is used to amplify the input signal after level conversion to obtain the modulated signal.

3. The signal processing circuit based on transformer isolation according to claim 2, characterized in that: The output unit comprises: a first MOS tube and a second MOS tube; the gate of the first MOS tube is connected to the output end of the level shift unit, and the source of the first MOS tube is connected to the power supply voltage; the gate of the second MOS tube is connected to the output end of the level shift unit, the source of the second MOS tube is grounded, and the drain of the second MOS tube is connected to the drain of the first MOS tube to form an electrical node, and the electrical node is connected to the input end of the isolation transformer.

4. The signal processing circuit based on transformer isolation according to claim 3, characterized in that: The output unit also includes a first amplifier and a second amplifier, wherein the input end of the first amplifier is connected to the output end of the level shift unit, and the output end of the first amplifier is connected to the gate of the first MOS tube; the input end of the second amplifier is connected to the output end of the level shift unit, and the output end of the second amplifier is connected to the gate of the second MOS tube.

5. The signal processing circuit based on transformer isolation according to claim 1, characterized in that: When the square wave signal jumps from a low level to a high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1 to mark the rising edge of the square wave signal, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the square wave signal; When the square wave signal changes from a high level to a low level, the signal modulation module first generates a low-level narrow pulse signal with a width of T1 to mark the falling edge of the original signal, and then generates a high-frequency square wave signal with a period of T2 to mark the low level of the square wave signal.

6. The signal processing circuit based on transformer isolation according to claim 1, characterized in that: The input signal is a DC signal. When the signal modulation module modulates the DC signal, it first generates a low-high level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the low and high levels of the DC signal.

7. The signal processing circuit based on transformer isolation according to claim 6, characterized in that: When the DC signal is at a DC low level, the signal modulation module first generates a low-level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the low level of the DC signal; When the DC signal is at a high level, the signal modulation module first generates a high-level narrow pulse signal with a width of T1, and then generates a high-frequency square wave signal with a period of T2 to mark the high level of the DC signal.

8. The signal processing circuit based on transformer isolation according to claim 1, characterized in that: The circuit also includes a capacitor connected in series between the primary coil of the isolation transformer and the signal modulation module.

9. The signal processing circuit based on transformer isolation according to claim 1 or 8, characterized in that: The circuit also includes a diode connected in series between the secondary coil of the isolation transformer and the signal demodulation module.

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