Analog signal transmission system, frequency converter, analog signal transmission method and computer readable storage medium

Abstract

The invention provides an analog signal transmission system, an analog signal transmission method, a frequency converter and a computer readable storage medium. The analog signal transmission system comprises: a PWM wave generation module configured to receive an analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted; the isolation transmission module is connected with the output end of the PWM wave generation module and is configured to receive the PWM wave signal and perform isolation transmission on the PWM wave signal; the processing module is connected with the output end of the isolation transmission module and is configured to receive the PWM wave signal from the output end of the isolation transmission module and demodulate the PWM wave signal so as to recover the analog signal; the processing module is configured to determine the pulse width duty ratio and the time sequence of the PWM wave signal based on the machine period; based on the duty ratio and the time sequence thereof, recovering the analog signal; the processing module is configured to adjust the closeness of the timing sequence based on a sampling method or a timing sequence harmonic method.

Description

Technical Field

[0001] The present invention generally relates to the field of communication technologies, and in particular, to an analog signal transmission system, an inverter, an analog signal transmission method, and a computer-readable storage medium. Background Art

[0002] The isolated transmission of analog signals depends on a special isolation operational amplifier chip, and this type of chip belongs to a special chip with a high dependence on suppliers. Due to the rarity of special chips, the cost of special chips is generally higher than that of conventional materials, and there is often a risk of supply interruption due to factors such as the international situation. Therefore, a technical solution with low cost, low supply risk, and high quality is needed to achieve the isolated transmission of analog signals.

[0003] The content in the background art section is only the technology known to the inventor and does not of course represent the prior art in this field. Summary of the Invention

[0004] In view of one or more of the problems existing in the prior art, the present invention provides an analog signal transmission system, including:

[0005] A PWM wave generation module configured to receive an analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted;

[0006] An isolation transmission module connected to the output end of the PWM wave generation module, configured to receive the PWM wave signal and perform isolated transmission on the PWM wave signal; and

[0007] A processing module connected to the output end of the isolation transmission module, and configured to receive the PWM wave signal from the output end of the isolation transmission module and perform demodulation to restore the analog signal; the processing module is configured to determine the pulse width duty ratio and its timing of the PWM wave signal based on the machine cycle; restore the analog signal based on the duty ratio and its timing; the processing module is configured to adjust the density of the timing based on the sampling method or the timing harmonic method.

[0008] Optionally, the PWM wave generation module includes a carrier generation circuit and a comparator, the carrier generation circuit is configured to generate a carrier signal; the comparator is connected to the output end of the carrier generation circuit and is configured to receive the carrier signal and the analog signal to be transmitted, and generate the PWM wave signal based on the carrier signal and the analog signal to be transmitted.

[0009] Optionally, the carrier generation circuit and the comparator are separately provided, and the processing module is connected to the carrier generation circuit and is configured to adjust the frequency of the carrier signal.

[0010] Optionally, the carrier generation circuit and the comparator are integrated; the analog signal transmission system further includes a preprocessing module, which is connected to the comparator and configured to receive the analog signal to be transmitted, and output it to the comparator after preprocessing the analog signal to be transmitted.

[0011] Optionally, the isolation transmission module includes an optocoupler or an optical fiber, where the optocoupler includes a light source and a photoreceiver, the light source is connected to the output end of the comparator and configured to receive the PWM wave signal and convert the PWM wave signal from an electrical signal into an optical signal; the photoreceiver is configured to receive the optical signal and convert the optical signal into an electrical signal and output it to the processing module.

[0012] Optionally, the processing module includes a signal interface, the signal interface is connected to the photoreceiver and configured to receive the electrical signal; the processing module is configured to demodulate the electrical signal to recover the analog signal.

[0013] Optionally, the processing module is configured to determine a first number of the machine cycles covered by the high level within each PWM wave signal period and a second number of the machine cycles covered by the low level; based on the first number and the second number, determine the pulse width duty ratio of the PWM wave signal, where the PWM wave signal period is greater than the machine cycle.

[0014] Optionally, the processing module is configured to adjust the density of the timing based on the sampling method, including: traversing the timing points corresponding to the high level within each PWM wave period based on the machine cycle; mapping the duty ratio of the PWM wave period corresponding to the traversed timing points based on the harmonic period, where the harmonic period is greater than the machine cycle and less than the PWM wave period.

[0015] Optionally, the processing module is configured to adjust the density of the timing based on the timing harmonic method, including: mapping the duty ratio of each PWM wave period to the timing points of the harmonic period, including: determining the remaining period of each PWM wave period based on the harmonic period; determining the number of the timing points of the harmonic period covered by each PWM wave period based on the remaining period; determining the timing points of the harmonic period corresponding to the duty ratio of each PWM wave period based on the harmonic period and the number of the timing points of the harmonic period.

[0016] Optionally, the analog signal transmission system further includes: a filtering module, which is configured to filter the recovered analog signal.

[0017] Optionally, the filtering module includes a FIR filter, and the FIR filter includes a single-pass FIR filter. The processing module is configured to perform time-domain filtering on the recovered analog signal based on the single-pass FIR filter.

[0018] Optionally, the processing module is further configured to constrain the time length of the time-domain filtering function of the FIR filter, including:

[0019] Determine the extreme points between adjacent zero-crossings of the time-domain filtering function;

[0020] Determine the modulus of the function values of the extreme points;

[0021] Intercept and retain the part of the time-domain filtering function whose modulus is greater than or equal to the threshold.

[0022] Optionally, the processing module is further configured to perform time-domain sampling on the intercepted and retained part of the time-domain filtering function based on the harmonic period.

[0023] Optionally, the processing module is further configured to evaluate the real-time performance of the analog signal transmission based on the demodulation delay and the filtering delay.

[0024] The present invention also provides an inverter, including the analog signal transmission system as described above.

[0025] The present invention also provides an analog signal transmission method implemented by the analog signal transmission system as described above, including:

[0026] Using a PWM wave generation module to receive the analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted;

[0027] Using an isolation transmission module to receive the PWM wave signal and perform isolation transmission on the PWM wave signal; and

[0028] Using a processing module to receive the PWM wave from the output end of the isolation transmission module and perform demodulation to recover the analog signal, including:

[0029] Using the processing module to determine the pulse width duty cycle and its timing of the PWM wave signal based on the machine cycle; and recovering the analog signal based on the duty cycle and its timing;

[0030] Using the processing module to adjust the density of the timing based on the sampling method or the timing harmonic method.

[0031] The present invention also provides a computer-readable storage medium, including computer-executable instructions stored thereon. The executable instructions, when executed by a processor, implement the analog signal transmission method as described above.

[0032] The analog signal transmission system of the present invention converts an analog signal into high and low levels by sampling the analog signal with a carrier wave and transmits it through an isolation transmission module. At the receiving end, a high-real-time algorithm is used to demodulate and filter the waveform output by the isolation transmission module, thereby completing the process of sending and receiving the analog signal. Using the sampling method for real-time signal transmission essentially poses requirements for the timing of the waveform and the operation speed. The present invention combines the method of digital signal processing with the PWM modulation method, and the advantages are as follows: The anti-interference ability of the PWM wave transmission is extremely strong, which can greatly ensure the quality of the real-time transmission signal. The cost of the PWM wave generation module and the isolation transmission module is much lower than that of special analog isolation chips, which can greatly reduce the total cost of the analog signal transmission system and reduce the risk of supply interruption of special analog isolation chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0034] Figure 1 FIG. shows a schematic diagram of an analog signal transmission system according to some embodiments of the present invention.

[0035] Figure 2 FIG. shows a schematic diagram of a PWM wave generation module according to some embodiments of the present invention.

[0036] Figure 3 FIG. shows a schematic diagram of a carrier generation circuit according to some embodiments of the present invention.

[0037] Figure 4 FIG. shows a schematic diagram of the principle of generating a PWM wave signal according to some embodiments of the present invention.

[0038] Figure 5 FIG. shows a schematic diagram of a PWM wave signal according to some embodiments of the present invention.

[0039] Figure 6 FIG. shows a schematic diagram of a PWM wave generation module according to some other embodiments of the present invention.

[0040] Figure 7 FIG. shows a schematic diagram of a PWM wave generation module according to some embodiments of the present invention.

[0041] Figure 8 FIG. shows a schematic diagram of an isolation transmission module according to some embodiments of the present invention.

[0042] Figure 9 FIG. shows a schematic diagram of an isolation transmission module according to some embodiments of the present invention.

[0043] Figure 10Schematic diagram showing the PWM wave signal output by the isolation transmission module according to some embodiments of the present invention.

[0044] Figure 11 Schematic diagram showing the analog signal obtained by demodulating the PWM wave signal by the processing module according to some embodiments of the present invention.

[0045] Figure 12 Schematic diagram showing the demodulation of the PWM wave signal by the processing module according to some embodiments of the present invention.

[0046] Figure 13 Schematic diagram showing the adjustment of the density of the time sequence by the processing module based on the time sequence harmonization method according to some embodiments of the present invention.

[0047] Figure 14 Schematic diagram showing the frequency domain filtering function according to some embodiments of the present invention.

[0048] Figure 15 Schematic diagram showing the time domain filtering function according to some embodiments of the present invention.

[0049] Figure 16 Schematic diagram showing the bilateral time domain filtering function according to some embodiments of the present invention.

[0050] Figure 17 Schematic diagram showing the unilateral time domain filtering function of the ideal low pass according to some embodiments of the present invention.

[0051] Figure 18 Schematic diagram showing the time domain sampling of the intercepted and retained time domain filtering function according to some embodiments of the present invention.

[0052] Figure 19 Schematic diagram showing the result after filtering the restored analog signal according to some embodiments of the present invention.

[0053] Figure 20 Schematic diagram showing the frequency converter according to some embodiments of the present invention.

[0054] Figure 21 Flowchart showing the analog signal transmission method according to some embodiments of the present invention. Detailed implementation manners

[0055] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are regarded as exemplary rather than restrictive in nature.

[0056] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0057] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0059] Numerous different embodiments or examples are provided below to implement different structures of the present invention. To simplify the present invention, components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0060] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not used to limit the present invention.

[0061] The present invention provides an analog signal transmission system. The analog signal transmission system includes a PWM wave generation module, an isolation transmission module, and a processing module. The PWM wave generation module is configured to receive an analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted. The isolation transmission module is connected to the output end of the PWM wave generation module and is configured to receive the PWM wave signal and perform isolation transmission on the PWM wave signal. The processing module is connected to the output end of the isolation transmission module and is configured to receive the PWM wave signal from the output end of the isolation transmission module and perform demodulation to recover the analog signal. The analog signal transmission system of the present invention can achieve isolation transmission of analog signals with low cost, low supply risk, and high quality. Details are introduced below.

[0062] Figure 1 A schematic diagram showing an analog signal transmission system 100 according to some embodiments of the present invention is shown. As Figure 1 shown, the analog signal transmission system 100 includes a PWM wave generation module 10, an isolation transmission module 20, and a processing module 30. The PWM wave generation module 10 is configured to receive an analog signal S1 to be transmitted and generate a PWM wave signal based on the analog signal S1 to be transmitted. The isolation transmission module 20 is connected to the output end of the PWM wave generation module 10 and is configured to receive the PWM wave signal and perform isolation transmission on the PWM wave signal. The processing module 30 is connected to the output end of the isolation transmission module 20 and is configured to receive the PWM wave signal from the output end of the isolation transmission module 20 and perform demodulation to recover the analog signal S1.

[0063] In some embodiments, the wave - generating mechanism of the analog signal S1 to be transmitted can be a synchronous wave - generating mechanism, that is, it depends on the feedback of the secondary side (receiver) to transmit the synchronization signal. In some embodiments, the wave - generating mechanism of the analog signal S1 to be transmitted can be an asynchronous wave - generating mechanism, that is, there is no requirement for the timing of the transmitter, and it does not have to rely on the secondary - side feedback to transmit the synchronization signal. This can simplify the hardware architecture, save hardware costs, and improve flexibility and versatility.

[0064] Figure 2 FIG. shows a schematic diagram of the PWM wave - generating module 10 according to some embodiments of the present invention. As Figure 2 shown, the PWM wave - generating module 10 includes a carrier - generating circuit 11 and a comparator 12. The carrier - generating circuit 11 and the comparator 12 can be separately arranged. The carrier - generating circuit 11 can generate a carrier signal S2. The comparator 12 is connected to the output end of the carrier - generating circuit 11, and can receive the carrier signal S2 and the analog signal S1 to be transmitted, and generate a PWM wave signal based on the carrier signal S2 and the analog signal S1 to be transmitted. Preferably, the PWM wave - generating module 10 can adopt an asynchronous PWM wave - generating module that does not depend on external synchronous timing.

[0065] Figure 3 FIG. shows a schematic diagram of the carrier - generating circuit 11 according to some embodiments of the present invention. As Figure 3 shown, the carrier - generating circuit 11 includes an operational amplifier KU29A, an operational amplifier KU29B, a resistor R241, a resistor R242, a resistor R243, a capacitor C219, a capacitor C221, and a capacitor C222. Among them, the negative input terminal of the operational amplifier KU29A is grounded, the positive input terminal is connected to its output terminal through the resistor R242, and its output terminal is connected to the negative input terminal of the operational amplifier KU29B through the resistor R241. The positive input terminal of the operational amplifier KU29B is grounded, and its output terminal is connected to the resistor R242 and the positive input terminal of the operational amplifier KU29A through the resistor R243. The operational amplifier KU29A is also connected to the ±15V voltage source and is grounded through the capacitors C221 and C222. The operational amplifier KU29B is also connected to the ±15V voltage source. The two ends of the capacitor C219 are respectively connected to the negative input terminal and the output terminal of the operational amplifier KU29B. The output terminal of the operational amplifier KU29B can output the carrier signal S2. The voltage at the connection point between the output terminal of the operational amplifier KU29A and the resistor R242 is V 1 . The voltage at the connection point between the positive input terminal of the operational amplifier KU29A and the resistors R242 and R243 is V 2 . The voltage at the output terminal of the operational amplifier KU29B is V out .

[0066] For V 1 and V out , there is:

[0067]

[0068] For V 1 , V 2 and V out , there is:

[0069]

[0070] From the fact that the negative input terminal of the operational amplifier KU29A is grounded, it can be known that the V 1 critical value of the potential inversion of V 2 is 0 (when V 2 is greater than 0, V 1 outputs a high level; when V 2 is less than 0, V 1 outputs a low level), that is:

[0071] V 2 | th = 0... (Equation 3).

[0072] Based on the above three equations, it can be obtained that the output frequency f of the carrier generation circuit 11 is:

[0073]

[0074] It can be obtained that the starting oscillation condition of the carrier generation circuit 11 is:

[0075]

[0076] It can be obtained that the peak value ‖V out ‖ of the output voltage of the carrier generation circuit 11 is:

[0077]

[0078] Among them, V CC is the supply voltage of the operational amplifier in this circuit. For example, ±15V, not limited to this.

[0079] The analog signal transmission system 100 of the present invention can output a carrier signal S2 through the carrier generation circuit 11 of the PWM wave generation module 10; by receiving the carrier signal S2 and the analog signal S1 to be transmitted through the comparator 12 and comparing the analog signal S1 to be transmitted and the carrier signal S2, a PWM wave signal can be obtained.

[0080] Figure 4 and Figure 5 show a schematic diagram of the principle of generating a PWM wave signal according to some embodiments of the present invention. As Figure 4As shown, the blue sine wave represents the analog signal S1 to be transmitted, and the orange triangle wave or sawtooth wave represents the carrier signal S2. When the amplitude of the carrier signal S2 (triangle wave or sawtooth wave) is greater than that of the analog signal S1 to be transmitted (the modulated wave), the comparator 12 (PWM wave generation module 10) outputs a high level (logic 1); otherwise, it outputs a low level (logic 0). That is to say, the present invention uses the carrier signal to sample the analog signal to be transmitted and then generates a PWM wave signal. As Figure 5 shown, the blue square wave represents the PWM wave signal.

[0081] Due to the amplitude change (nonlinearity) of the analog signal S1 to be transmitted, within one sampling period (carrier period 1 / f), the amplitude of the analog signal S1 to be transmitted is different, and the time when the amplitude of the analog signal S1 to be transmitted is greater than or less than the carrier signal S2 will change accordingly, making the proportion of the time of logic 1 in the PWM wave signal different in each sampling period. This proportion is called the duty cycle. Therefore, the analog signal transmission system 100 can transmit amplitude information according to the duty cycle of logic 1 in the sampling period of the PWM wave signal.

[0082] On the other hand, based on the nonlinearity of the analog signal S1 to be transmitted, when the amplitude of the analog signal S1 to be transmitted changes, the width of the PWM wave in each sampling period is not uniform. At different sampling points, the duration between two adjacent rising edges is different, that is, the period of the PWM wave signal is not uniform, which will limit the real-time performance of signal transmission and thus reduce the signal transmission quality. Therefore, improving the uniformity of the duration between two adjacent rising edges (that is, improving the uniformity of the period of the PWM wave signal) helps to achieve high-quality real-time signal transmission.

[0083] In some embodiments, the uniformity of the PWM wave signal period can be improved by increasing the carrier frequency. For example, the processing module 30 can be connected to the carrier generation circuit 11 and configured to adjust the frequency f of the carrier signal S2 to improve the non-uniformity of the PWM wave signal period. For example, based on Figure 3 and (Equation 4), at least one of the resistor R241, resistor R242, resistor R243, and capacitor C219 is adjustable, and the processing module 30 can adjust the resistance or voltage of at least one of the resistor R241, resistor R242, resistor R243, and capacitor C219 to increase the frequency f of the carrier signal S2 (for example, adjust it to 600 - 800 MHz). In this way, the non-uniformity of the PWM wave signal period can be improved to a certain extent.

[0084] The present invention does not limit the setting manner of the carrier generation circuit 11 and the comparator 12 in the PWM wave generation module 10. In some embodiments, as Figure 2 and Figure 3As shown, the carrier generation circuit 11 and the comparator 12 are separately arranged. In this way, the flexibility of the PWM wave generation module 10 can be improved, and the dynamic adjustment range of the carrier frequency f can be increased. Figure 6 FIG. shows a schematic diagram of a PWM wave generation module 10 according to some other embodiments of the present invention. As Figure 6 shown, the carrier generation circuit 11 and the comparator 12 can be integrally arranged. For example, the carrier generation circuit 11 and the comparator 12 can be integrated in a chip capable of modulating the analog signal S1 to be transmitted into a PWM wave. The chip can be a TL594 chip or a TL494 chip or other similar chips. In this way, the size and hardware cost of the PWM wave generation module 10 can be reduced. In practical applications, it can be set according to requirements.

[0085] The following takes the TL594 chip as an example for introduction. It should be noted that the same applies to other similar chips, and details will not be repeated here.

[0086] Figure 7 FIG. shows a schematic diagram of a PWM wave generation module (e.g., TL594 chip) according to some embodiments of the present invention. As Figure 6 and Figure 7 shown, the carrier generation circuit 11 and the comparator 12 can be integrated inside the TL594 chip. The carrier generation circuit 11 can be implemented by an oscillator built in the TL594 chip. The comparator 12 can be implemented by a PWM comparator built in the TL594 chip.

[0087] As Figure 6 and Figure 7 shown, the analog signal transmission system 100 may further include a preprocessing module 13. The preprocessing module 13 is connected to the comparator 12 and is configured to receive the analog signal S1 to be transmitted, and after preprocessing the analog signal S1 to be transmitted, output it to the comparator 12. Specifically, the preprocessing module 13 can preprocess the analog signal S1 to be transmitted from a bipolar voltage signal (e.g., -3.3 to 3.3V) into a unipolar voltage signal (e.g., 0 to 3.3V), and output it to pin 3 or pin 4 of the TL594 chip, and transmit it to the comparator 12 through pin 3 or pin 4. The oscillator built in the TL594 chip provides a carrier signal S2, and outputs it to the comparator 12 through pin 5 and pin 6. The comparator 12 compares the carrier signal S2 output from pin 5 or 6 and the analog signal S1 to be transmitted preprocessed by the preprocessing module 13 output from pin 3 or 4, and after comparison, outputs a PWM wave signal (e.g., 300kHz) from the output terminal Output1 (pin C1) and the output terminal Output2 (pin C2) of the TL594 chip. It should be noted that the preprocessing module 13 can be separately arranged, or can be integrated in the processing module 30.

[0088] In the prior art, TL594 chips or TL494 chips are usually used in switching power supplies for power control. The applicant of the present application innovatively uses them for signal transmission. By using TL594 chips or TL494 chips, the analog signal S1 to be transmitted can be modulated into a PWM wave for subsequent isolated transmission in the isolation transmission module 20. It can be understood that isolated transmission means that the signal sending end (for example, 10 kV) and the signal receiving end (for example, 5 V) have different power supply systems, such as a high-voltage device sampling system that separates high and low voltages. For example, the control system needs to collect the input and output parameters of high-voltage and high-power equipment, and the control system itself is a weak-current system, which is extremely sensitive to the input and output of high voltage and high power. Therefore, the meaning of isolated transmission can be: only transmit the sampling information of the input and output, and cut off the electrical connection between the high-voltage and high-power input and output and the control system. For the present application, for example, the analog signal S1 to be transmitted comes from a high-voltage and high-power device, that is, a high-voltage and high-power strong-current system (such as a high-voltage frequency converter, etc.), the analog signal transmission system 100 is a weak-current system, and the isolation transmission module 20 can cut off the electrical connection between the high-voltage and high-power input and output and the analog signal transmission system 100, and only transmit the sampling information of the weak-current input and output (such as a PWM wave signal), thereby realizing isolated transmission.

[0089] The analog signal S1 to be transmitted can be one or more paths. When the analog signal S1 to be transmitted is multiple paths, due to factors such as device deviation, the multiple paths of analog signals S1 to be transmitted may be inconsistent (such as amplitude change). To ensure the consistency of the multiple paths of analog signals S1 to be transmitted, in some embodiments, a global clock can be used for synchronization. In some embodiments, a zero-point correction method can be used for synchronization. For example, before the high-voltage and high-power strong-current system is powered on and after the weak-current system is powered on, the signal input to the primary side of the isolation transmission module 20 is zero. At this time, if the signal period after sampling through the carrier signal S2 is necessarily uniform. At this time, this period can be used as a reference to correct the inconsistency of the multiple paths of analog signals S1 to be transmitted caused by factors such as device deviation, and to correct the zero offset according to the duty cycle of the positive and negative half-cycles of the carrier signal S2, improving flexibility and versatility.

[0090] In some embodiments, the PWM wave signal output by the comparator 12 (carrier generation circuit 11) can be isolated and transmitted between the primary and secondary sides through the isolation transmission module 20. The following is a specific introduction.

[0091] In some embodiments, the isolation transmission module 20 includes an optocoupler or an optical fiber. The working principles of the optocoupler and the optical fiber are basically the same. For convenience, the isolation transmission module 20 of the present invention will be introduced below by taking the optocoupler as an example. Figure 8 The schematic diagram of the isolation transmission module 20 according to some embodiments of the present invention is shown. AsFigure 8 As shown, the optocoupler (isolation transmission module 20) includes a light source 21 and a light receiver 22. The light source 21 is connected to the output terminal of the comparator 12, configured to receive the PWM wave signal, and convert the PWM wave signal from an electrical signal into an optical signal and output it. The light receiver 22 is configured to receive the optical signal, and convert the optical signal into an electrical signal and output it to the processing module 30. Preferably, the optocoupler is a high-speed optocoupler (abbreviation: high-speed opto-coupler).

[0092] Figure 9 A schematic diagram of the isolation transmission module 20 according to some embodiments of the present invention is shown. In this embodiment, the optocoupler may be the chip HCPL-2601, but is not limited thereto. As Figure 7 and Figure 8 shown, pin 2 and pin 3 are respectively connected to the anode and cathode of the light source 21. The optocoupler (isolation transmission module) 20 can receive the PWM wave signal output by the PWM wave generation module 10 through pin 2. The light receiver 22 is connected to pins 6 and 7, and pin 6 can output the PWM wave signal to the processing module 30. The PWM wave signal is input from pin 2 to the optocoupler (isolation transmission module) 20, and a high-speed PWM wave signal can be output at its isolated output terminal (pin 6). Figure 10 A schematic diagram of the PWM wave signal output by the isolation transmission module 20 according to some embodiments of the present invention is shown.

[0093] In some embodiments, the processing module 30 includes a signal interface. As Figure 8 shown, the signal interface may be an I / O port. The signal interface is connected to the light receiver 22 and configured to receive the PWM wave electrical signal. The processing module 30 demodulates the PWM wave electrical signal received by the signal interface to recover the analog signal. When the PWM wave is transmitted from the primary side (light source 21) to the secondary side (light receiver 22) via the optocoupler (isolation transmission module) 20, due to its high and low level nature, it can be directly received through the I / O port of the processing module 30, breaking through the limitation that the real-time analog signal still needs to be input to the inside of the processing module through the AD sampling port after isolation transmission under normal circumstances. That is to say, the PWM wave signal output by the isolation transmission module 20 of the present invention can be directly recognized, received and demodulated by the processing module 30 without an AD sampling port, so as to recover the analog signal S1, which can reduce the device size and cost. Figure 11 A schematic diagram of the analog signal obtained by the processing module 30 demodulating the PWM wave signal according to some embodiments of the present invention is shown. Thus, the transmission of the analog signal is realized, the versatility of the processing module 30 is improved, and at the same time its size and cost are reduced.

[0094] In some embodiments, the processing module 30 / preprocessing module 13 may include components or circuits such as a signal interface, a processing chip, a processing circuit, a Central Processing Unit (CPU), a Micro Control Unit (MCU), a Digital Signal Processor (DSP), other general-purpose processors, an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), a Complex Programmable Logic Device (CPLD), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0095] In some embodiments, the processing module 30 is configured to determine the pulse width duty ratio and its timing of the PWM wave signal based on machine cycles. When the PWM wave signal is received by the processing module 30, the processing module 30 can determine the duty ratio of the pulse width by counting the number of machine cycles in the high and low level states of the PWM wave signal received through the signal interface. Specifically, the processing module 30 is configured to determine a first number m1 of machine cycles covered by the high level within each PWM wave cycle, and a second number m2 of machine cycles covered by the low level; based on the first number m1 and the second number m2, determine the pulse width duty ratio of the PWM wave. The PWM wave period Tpwm is greater than the machine cycle Tm. m1 and m2 are positive integers.

[0096] Figure 12 A schematic diagram showing the demodulation of the PWM wave signal by the processing module 30 according to some embodiments of the present invention is shown. As Figure 12 shown, the blue square wave represents a PWM wave cycle signal. The black arrows represent machine cycles, where the upward black arrows represent the machine cycles covered by the high-level PWM wave signal, and the downward arrows represent the machine cycles covered by the low-level PWM wave signal. The PWM wave signal period is greater than the machine cycle. Each PWM signal cycle can cover multiple machine cycles. The processing module 30 can determine the duty ratio of each PWM cycle by counting the number of machine cycles covered by the high and low levels within each PWM cycle. For example, taking Figure 12 a PWM wave signal cycle shown as an example, within this PWM wave signal cycle, the number of machine cycles covered by the high level is m1, and the number of machine cycles covered by the low level is m2, then the duty ratio of this PWM cycle is m1 / (m1 + m2). By this way, traversing all cycles of the PWM wave signal, all duty ratios of the PWM signal can be determined.

[0097] To solve the problem of non-uniform PWM wave signal period for signal restoration, the processing module 30 can record the timing sequences of all machine cycles used to determine the duty cycle, so as to clarify in which time period and at which time points each duty cycle is obtained, and ensure that there is a timing basis for each duty cycle after counting. Based on the pulse width duty cycle of the PWM wave signal and its timing, the processing module 30 can restore the analog signal, such as Figure 11 shown. This solves the problem of waveform detuning (i.e., time delay) caused by non-uniform PWM wave signal period.

[0098] Since the crystal oscillator frequency of the processing module 30 is relatively high (higher than the carrier frequency), if all the duty cycles obtained within one PWM wave cycle are aligned with each machine cycle, it will cause excessive data volume and consume too much processing resources. If the sampling timing density is adjusted at the beginning of counting, it will lead to a loss of accuracy in calculating the duty cycle. In some embodiments, the timing alignment of the sampling signal can rely on the system-wide synchronous clock signal, that is, global synchronous logic is used for timing alignment. In some embodiments, the timing density can be adjusted by the timing density harmonization method. For example, the processing module 30 can adjust the timing density based on the sampling method or the timing harmonization method to balance processing resources and accuracy. That is, asynchronous logic can be used to sample the timing logic at any phase based on the internal clock of the logic chip of the processing module 30 to harmonize the timing density and improve flexibility and versatility. For example, this method can store the duty cycle data calculated in the previous cycle according to the sampling timing of the current cycle, and at the same time calculate the duty cycle of the current cycle and store it in the next cycle, and so on. Compared with the method of using global synchronous logic for timing alignment, asynchronous logic can greatly simplify the implementation difficulty of sampling the signal before isolation and modulating the PWM wave, and the circuit when performing isolated transmission, that is, there is no need for a special channel to transmit the clock signal for global synchronization, greatly reducing the usage of circuit devices and the circuit complexity during multi-channel transmission and long-distance transmission, which helps to reduce the overall complexity, size and cost.

[0099] In some embodiments, the processing module 30 is configured to adjust the density of the timing based on the sampling method, including: the processing module 30 can traverse the timing points corresponding to the high level within each PWM wave period based on the machine cycle; map the duty cycle of the PWM wave period corresponding to the traversed timing points based on the harmonic cycle, where the harmonic cycle is greater than the machine cycle and less than the PWM wave period, and the harmonic cycle can be an integer multiple of the machine cycle. That is to say, the sampling method is to traverse all the timing points of the machine cycle corresponding to the duty cycle of logic 1 within each PWM wave period again, and then remap the duty cycle value of the PWM wave period according to the established timing interval (harmonic cycle). For example, the machine cycle is ΔT m , and the harmonic cycle is ΔT n . The processing module 30 can traverse the PWM wave signal output by the isolation transmission module 20 according to the machine cycle ΔT m , and according to the harmonic cycle, that is, every ΔT n , that is, the machine cycle ΔT m corresponding PWM wave duty cycle is stored. It can be understood that the sampling method will consume the same time again (the time for the processing module 30 to recover the analog signal S1 based on the PWM wave) to present the analog signal data, that is, trading time for space; it is suitable for processing modules with not too high requirements for time delay and limited resource allocation.

[0100] In some embodiments, the processing module 30 is configured to adjust the density of the timing based on the timing harmonic method, including: mapping the duty cycle of each PWM wave period to the timing points of the harmonic cycle, including: determining the remaining cycle of each PWM wave period based on the harmonic cycle; determining the number of timing points of the harmonic cycle covered by each PWM wave period based on the remaining cycle; determining the timing points of the harmonic cycle corresponding to the duty cycle of each PWM wave period based on the harmonic cycle and the number of timing points of the harmonic cycle. That is to say, the timing harmonic method is to use a computational method to map the duty cycle of the PWM wave to the time points of the established timing interval ΔT n at one time.

[0101] For the time points of the established timing interval, determine the machine cycle ΔT m and the number m of machine cycles covered by each PWM wave period, and the harmonized timing interval ΔT n . The finally calculated quantity is converted into the number n of sampling points included in each PWM wave period after harmonization. Through ΔT n and n, a new sampling timing can be output. This algorithm requires processing resources to calculate the above parameters, and the data generation speed is extremely fast. Therefore, it is an algorithm that trades space for time.

[0102] Since the harmonic cycle ΔTn and the machine cycle ΔT m have unequal lengths. Therefore, for the inherently unequal PWM sampling periods, there must be remaining incomplete periods, which can be named the remaining periods. Figure 13 FIG. shows a schematic diagram of the processing module 30 adjusting the temporal density based on the temporal harmonic method according to some embodiments of the present invention. As Figure 13 shown, the interval between two adjacent arrows is the machine cycle ΔT m . The interval between the black dots is the harmonic period ΔT n . The black dots are the sampling points for temporal harmonic. By the harmonic period ΔT n and the number of sampling points n, a new sampling timing can be output.

[0103] For each calculation, the length of the remaining period needs to be recorded. For the i-th calculation, the remaining period of this time can be defined as ΔT i . In other words, for the i-th calculation, the length of the remaining period of the previous time is ΔT i-1 . Therefore, after harmonization, the expression for the number of sampling points n of the current period is:

[0104]

[0105] For ΔT i calculation, an iterative method can be used, based on ΔT i-1 to calculate ΔT i :

[0106] ΔT i = mΔT m -(ΔT n -ΔT i-1 )-(n - 1)ΔT n = mΔT m - nΔT n + ΔT i-1 ……(Equation 8).

[0107] According to (Equation 8), the processing module 30 can determine the position of the timing corresponding to each duty cycle after harmonization, so as to recover the analog signal, as Figure 11 shown.

[0108] Since each timing point in the same PWM sampling period corresponds to the same duty cycle, the demodulated waveform is actually composed of a series of stepped points, as Figure 11 shown. This step can capture harmonics in the frequency domain. This harmonic actually does not exist in the sampled waveform, but appears due to the demodulation method and becomes detuned into noise. To ensure the signal waveform quality, this harmonic can be filtered to ensure the signal quality.

[0109] In some embodiments, the analog signal transmission system 100 further includes a filtering module (not shown in the figure), and the filtering module is configured to perform filtering processing on the recovered analog signal. The filtering module can be set separately or can be integrated into the processing module 30. The filtering module can be implemented by a hardware circuit or by a software algorithm, and the present invention does not limit this.

[0110] Filtering can be performed on spectral components that should not appear in the frequency domain of the analog signal. The filtering operation can be regarded as the product of the filtering function in the frequency domain and the signal spectrum. Figure 14 A schematic diagram showing the frequency domain filtering function according to some embodiments of the present invention is shown. Let the frequency domain filtering function be H(jω), and the spectrum function of the signal be F(jω). At this time, the signal spectrum Y(jω) after being filtered by the filtering module is:

[0111] Y(jω) = H(jω)F(jω) …… (Equation 9).

[0112] However, the frequency information itself has the property of "hindsight", that is, its frequency can only be known after receiving the analog signal waveform. Therefore, operating on the analog signal in the frequency domain will undoubtedly increase its phase shift and the signal processing time.

[0113] To solve this problem, the filtering module can include a FIR filter. The processing module 30 can use the FIR filtering algorithm to perform the inverse Fourier transform of the filtering function H(jω) in the frequency domain into the time domain:

[0114] y(t) = h(t) * f(t) …… (Equation 10).

[0115] In this way, the original product in the frequency domain (Equation 9) can be transformed into a convolution in the time domain (Equation 10). Figure 15 A schematic diagram showing the time domain filtering function according to some embodiments of the present invention is shown.

[0116] If a low-pass filtering function is used in the frequency domain, then this function is symmetrically distributed about the frequency with respect to the y-axis, that is, it is an even function with respect to the frequency, as Figure 15 shown. According to the parity of the Fourier transform, it can be obtained that the inverse Fourier transform of the filtering function in the time domain is also an even function, that is, it satisfies:

[0117] h(-t) = h(t) …… (Equation 11).

[0118] Therefore, for an even function, its convolution satisfies:

[0119]

[0120] That is:

[0121]

[0122] That is:

[0123]

[0124] It can be seen that if the filtering function of the time-domain signal is an even function, then its convolution with the signal function is their cross-correlation function.

[0125] For discrete sampling points themselves, the discrete Fourier transform can be used to convert the convolution into a convolution sum, that is:

[0126]

[0127] If the filtering function is an even function, then there is:

[0128]

[0129] If the upper and lower limits (∞) of the sequence are ignored, this operation is a linear operation most suitable for processing by a logic chip, that is, the data points are multiplied by the filtering function and then accumulated as the output of the i-th point.

[0130] If the filtering function is an ideal low-pass filtering function, then its corresponding waveform is a square wave:

[0131]

[0132] Then its time-domain filtering function h(t) is:

[0133]

[0134] In Equation 18, ω 0 is the phase and t is the time.

[0135] Figure 16 FIG. shows a schematic diagram of a bilateral time-domain filtering function according to some embodiments of the present invention. However, there are two problems at this time. One is that the time sequence cannot be negative. The other is that the sequence length of the filter function cannot be infinite. For the first problem, the operation can be performed using a unilateral filtering function according to the time sequence, or a unilateral filtering function of a band-stop filter can be used to solve the problem that the time sequence cannot be negative. For example, the FIR filter may include a single-pass FIR filter. The processing module 30 is configured to perform time-domain filtering on the restored analog signal based on the single-pass FIR filter. Figure 17 FIG. shows a schematic diagram of a unilateral time-domain filtering function of an ideal low-pass according to some embodiments of the present invention, as Figure 17 shown, the time sequence is not negative.

[0136] For the second problem, a saliency algorithm can be used to constrain the sequence length of the filtering function. Since there are multiple zero-crossing points in the time-domain filtering function, if a simple threshold is set, it will cause the sampling to stop near the first zero-crossing point, resulting in a poor filtering effect. Therefore, the saliency algorithm can be used to constrain the length of the filtering function to solve the problem that the sequence length of the filter function cannot be infinite and to achieve a good filtering effect. The saliency algorithm can be understood as the degree to which a signal differs from a reference signal within a specific neighborhood or the degree to which the signal within the neighborhood differs from other parts.

[0137] In some embodiments, the processing module 30 is configured to constrain the time length of the time-domain filtering function of the FIR filter, including: determining the extreme points between adjacent zero-crossing points of the time-domain filtering function; determining the modulus of the function values of the extreme points; and intercepting and retaining the part of the time-domain filtering function whose modulus is greater than or equal to the threshold. Specifically, an appropriate-width neighborhood can be selected in the time domain. For example, the width between two adjacent zero points can be used as the neighborhood, the extreme points within each neighborhood are determined, and the modulus of the function values of the extreme points within each neighborhood is taken. When the modulus value (or the square of the modulus value) of the extreme point within the neighborhood is greater than or equal to the threshold, this part of the time-domain filtering function is intercepted and retained. When the modulus value (or the square of the modulus value) of the extreme point within the neighborhood is less than the threshold, the subsequent part of the time-domain filtering function is no longer used. In this way, the processing module can implement the constraint on the time length of the time-domain filtering function based on the saliency algorithm.

[0138] For discrete signals, the time-domain filtering function needs to be adapted to the discreteness of the function. Therefore, after the constraint on the time length of the time-domain filtering function is completed, the intercepted and retained filtering function needs to be sampled discretely in the time domain.

[0139] In some embodiments, the processing module 30 is configured to perform time-domain sampling on the intercepted and retained part of the time-domain filtering function based on the harmonic period. That is to say, the processing module 30 can perform time-domain sampling on the intercepted and retained part of the time-domain filtering function according to ΔT determined in the timing density harmonic algorithm. n Perform time-domain sampling on the intercepted and retained part of the time-domain filtering function. Figure 18 FIG. shows a schematic diagram of performing time-domain sampling on the intercepted and retained time-domain filtering function according to some embodiments of the present invention. As Figure 18 shown, the red circles represent the sampling points for performing time-domain sampling on the intercepted and retained time-domain filtering function. Based on the sampling values of these sampling points, the function values of the filtering function can be determined. Combining with (Equation 16), the output of the i-th point can be determined. By traversing all these sampling points, the time-domain filtering of the restored analog signal can be completed. Figure 19 FIG. shows a schematic diagram after filtering the restored analog signal according to some embodiments of the present invention. As Figure 19 shown, relative to Figure 11An example of the unfiltered restored analog signal (i.e., before filtering) is shown. After filtering, the signal waveform is smoother, the harmonics are significantly reduced, the noise is effectively suppressed, the signal distortion is reduced, and the signal transmission quality is ensured.

[0140] It should be noted that Figures 14 to 18 The filtering function shown is only exemplary and not necessarily the filtering function actually used. In addition, Figure 11 and Figure 19 The analog signal waveform shown is only exemplary, and the present invention is not limited thereto. In practical applications, it can be set according to requirements.

[0141] In some embodiments, the processing module 30 is further configured to evaluate the real-time performance of the analog signal transmission based on the demodulation delay and the filtering delay.

[0142] According to the algorithm characteristics, the delay of the demodulation algorithm (demodulation delay) is theoretically the maximum period in the uneven period ΔT k in the PWM wave. This means that the higher the carrier sampling frequency, the lower the theoretical delay. The demodulation delay ΔT dem is:

[0143] ΔT dem = max{ΔT k , k = different periods of PWM}... (Equation 19).

[0144] According to the algorithm characteristics, the delay of the filtering algorithm (filtering delay) is the number of waveform periods in the time domain covered by the significance of the filtering function. According to the characteristics of the Fourier transform, the period in the time domain corresponds to the cut-off frequency of the frequency domain sampling. If the number of periods of the time domain filtering function covered by the significance is l, and l is also the number of extreme points between adjacent zero-crossings of the time domain filtering function intercepted and retained as described above. l is less than n. The filtering delay ΔT filter is:

[0145]

[0146] Then the theoretical total delay ΔT total is:

[0147] ΔT total = ΔT dem + ΔT filter ... (Equation 21).

[0148] In the filtering delay ΔT filter , the purpose of setting f filter,edge is to eliminate demodulation detuning. And the cut-off frequency of demodulation detuning is the frequency corresponding to the maximum delay of the PWM wave. Therefore, there is:

[0149] ΔT filter = lΔT dem ……(Equation 22).

[0150] Therefore, the total time delay ΔT total is as follows:

[0151] ΔT total = (l + 1)ΔT dem ……(Equation 23).

[0152] Therefore, the processing module 30 can evaluate the total time delay of the analog signal transmission based on at least part of (Equation 19) to (Equation 23), so as to evaluate the real-time performance of the signal transmission.

[0153] It can be seen that to ensure the real-time performance of the analog signal transmission, the following two conditions can be taken into account: one is to reasonably set the filtering function and the significance level (affecting l), and the other is to use a high-frequency PWM wave generator (affecting ΔT dem ).

[0154] In some embodiments, the carrier generation circuit 11 can provide a sampling frequency of 15 kHz, the significance level is controlled within l = 5 cycles, and the processing module 30 evaluates that the total time delay is about 0.4 ms. For a high-speed (e.g., 300 kHz) PWM wave generation module, the theoretical time delay is about 20 μs. After the processing module 30 evaluates the time delay and determines that it is less than the time delay threshold, it can be determined that the analog signal transmission system of the present invention meets the requirements for the real-time performance of the analog signal transmission. It should be noted that these values are only for exemplary introduction, and the present invention is not limited thereto.

[0155] The traditional technical solution uses a special analog isolation operational amplifier chip, such as the ISO124 chip. The technical solution of the present invention uses the PWM wave generation module 10 as an operational amplifier and the isolation transmission module 20 as an isolation device, and the cost is only about 10.7% of the traditional technical solution, greatly reducing the cost. The analog signal transmission system of the present invention converts the analog signal into high and low levels by sampling the analog signal with a carrier and transmits it through the isolation transmission module, and uses a high-real-time algorithm to demodulate and filter the waveform output by the isolation transmission module at the receiving end, thereby completing the process of sending and receiving the analog signal. Using the sampling method for real-time signal transmission essentially puts forward requirements for the timing of the waveform and the operation speed. The present invention combines the digital signal processing method with the PWM modulation method, and the advantages are as follows: the anti-interference ability of the PWM wave transmission is extremely strong, which can greatly ensure the quality of the real-time transmission signal. The cost of the PWM wave generation module and the isolation transmission module is much lower than that of the special analog isolation chip, which can greatly reduce the total cost of the analog signal transmission system and reduce the risk of supply interruption of the special analog isolation chip.

[0156] The present invention also provides an inverter. Figure 20Schematic diagram showing a frequency converter according to some embodiments of the present invention. As Figure 20 shown, the frequency converter 200 includes the analog signal transmission system 100 as described above. The frequency converter 200 can be a high-voltage frequency converter or a medium- and low-voltage frequency converter. By adopting the analog signal transmission system 100 as described above, the frequency converter of the present invention can achieve low-cost and high-quality isolation transmission of analog signals, meeting the requirement of the main control unit (not shown in the figure) of the frequency converter for real-time control of the input and output voltage states of the frequency converter.

[0157] The present invention also provides an analog signal transmission method. Figure 21 Flowchart showing an analog signal transmission method 300 according to some embodiments of the present invention. As Figure 21 shown, the analog signal transmission method 300 includes steps S310 to S330.

[0158] In step S310, a PWM wave generation module is used to receive the analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted. In step S320, an isolation transmission module is used to receive the PWM wave signal and perform isolation transmission on the PWM wave signal. In step S330, a processing module is used to receive the PWM wave from the output end of the isolation transmission module and perform demodulation to recover the analog signal. Step S330 includes: using the processing module to determine the pulse width duty ratio and its timing of the PWM wave signal based on the machine cycle; recovering the analog signal based on the duty ratio and its timing; using the processing module to adjust the density of the timing based on the sampling method or the timing harmonic method. The analog signal transmission method 300 and its respective steps can be executed by the analog signal transmission system 100 as described above. The analog signal transmission method of the present invention performs isolation transmission of analog signals through the analog signal transmission system 100, with low cost and high quality.

[0159] The present invention also provides a computer-readable storage medium, including computer-executable instructions stored thereon, and the executable instructions implement the analog signal transmission method 300 as described above when executed by a processor.

[0160] The present invention may be embodied in the form of a computer program product implemented on one or more storage media that contain program code. Computer-usable storage media include both permanent and non-permanent, removable and non-removable media, and may implement the storage of information by any method or technology. The information may be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to: PRAM, SRAM, DRAM, other types of RAM, ROM, EEPROM, flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital video disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information accessible by a computing device.

[0161] It should be noted that the present invention may only include Figures 1 - 21 any one or more features of any one or more of the embodiments. In other words, not all of the features shown need to be implemented simultaneously in the analog signal transmission system / analog signal transmission method / frequency converter of the present invention.

[0162] It should be noted that although several modules of the analog signal transmission system are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present invention, the features and functions of the two or more modules described above may be implemented in one module. Conversely, the features and functions of one module described above may be further divided and embodied by multiple modules.

[0163] It should be noted that this specification provides method operation steps such as in the embodiments or schematic diagrams, but based on routine or non-creative labor, there may be more or fewer operation steps. The step order listed in the embodiments is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual system or device product is executed, it may be executed in the method order shown in the embodiments or flowcharts or executed in parallel.

[0164] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art may still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An analog signal transmission system, characterized in that: include: A PWM wave generating module, wherein the PWM wave generating module is configured to receive an analog signal to be transmitted and generate a PWM wave signal based on the analog signal to be transmitted; an isolation transmission module, the isolation transmission module is connected to the output end of the PWM wave generation module, configured to receive the PWM wave signal and perform isolation transmission on the PWM wave signal; and A processing module, the processing module is connected to the output end of the isolation transmission module and is configured to receive the PWM wave signal from the output end of the isolation transmission module and perform demodulation to restore the analog signal; The processing module is configured to determine the pulse width duty cycle and timing of the PWM wave signal based on a machine cycle; Based on the duty cycle and its timing, recover the analog signal; The processing module is configured to adjust the density of the time series based on a sampling method or a time series harmonization method.

2. The analog signal transmission system according to claim 1, characterized in that: The PWM wave generation module includes a carrier generating circuit and a comparator, wherein the carrier generating circuit is configured to generate a carrier signal; the comparator is connected to the output end of the carrier generating circuit and is configured to receive the carrier signal and the analog signal to be transmitted, and generate the PWM wave signal based on the carrier signal and the analog signal to be transmitted.

3. The analog signal transmission system according to claim 2, characterized in that: The carrier generating circuit and the comparator are separately arranged, and the processing module is connected to the carrier generating circuit and configured to adjust the frequency of the carrier signal.

4. The analog signal transmission system according to claim 2, characterized in that: The carrier generating circuit and the comparator are integrated; the analog signal transmission system also includes a preprocessing module, which is connected to the comparator and configured to receive the analog signal to be transmitted, and output the analog signal to be transmitted to the comparator after preprocessing.

5. The analog signal transmission system according to claim 2, characterized in that: The isolated transmission module includes a photoelectric coupler or an optical fiber, wherein the photoelectric coupler includes a light source and a light receiver, wherein the light source is connected to the output end of the comparator and is configured to receive the PWM wave signal and convert the PWM wave signal from an electrical signal to an optical signal; the light receiver is configured to receive the optical signal, convert the optical signal into an electrical signal and output it to the processing module.

6. The analog signal transmission system according to claim 5, characterized in that: The processing module comprises a signal interface, which is connected to the light receiver and configured to receive the electrical signal; the processing module is configured to demodulate the electrical signal to restore the analog signal.

7. The analog signal transmission system according to any one of claims 1 to 6, characterized in that: The processing module is configured to determine a first number of machine cycles covered by a high level and a second number of machine cycles covered by a low level within each PWM wave signal period; based on the first number and the second number, determine a pulse width duty cycle of the PWM wave signal, wherein the PWM wave signal period is greater than the machine cycle.

8. The analog signal transmission system according to any one of claims 1 to 6, characterized in that: The processing module is configured to adjust the density of the timing based on a sampling method, including: based on the machine cycle, traversing the timing points corresponding to the high level in each PWM wave cycle; based on the harmonization cycle, mapping the duty cycle of the PWM wave cycle corresponding to the traversed timing points, wherein the harmonization cycle is greater than the machine cycle and less than the PWM wave cycle.

9. The analog signal transmission system according to any one of claims 1 to 6, characterized in that: The processing module is configured to adjust the density of the timing based on the timing harmonization method, including: mapping the duty cycle of each PWM wave cycle to the timing point of the harmonization cycle, including: determining the remaining cycle of each PWM wave cycle based on the harmonization cycle; determining the number of timing points of the harmonization cycle covered by each PWM wave cycle based on the remaining cycle; determining the timing point of the harmonization cycle corresponding to the duty cycle of each PWM wave cycle based on the harmonization cycle and the number of timing points of the harmonization cycle.

10. The analog signal transmission system according to any one of claims 1 to 6, characterized in that: Also includes: A filtering module is configured to perform filtering processing on the restored analog signal.

11. The analog signal transmission system according to claim 10, characterized in that: The filtering module includes a FIR filter, the FIR filter includes a single-pass FIR filter, and the processing module is configured to perform time-domain filtering on the restored analog signal based on the single-pass FIR filter.

12. The analog signal transmission system according to claim 11, characterized in that The processing module is further configured to constrain the time length of the time domain filter function of the FIR filter, including: Determine the extreme value points between adjacent zero-crossing points of the time domain filter function; Determine the modulus of the function value at the extreme point; The portion of the time domain filter function in which the modulus is greater than or equal to the threshold is intercepted and retained.

13. The analog signal transmission system according to claim 11, characterized in that: The processing module is further configured to perform time-domain sampling on the truncated and retained time-domain filter function portion based on the harmonization period.

14. The analog signal transmission system according to claim 11, characterized in that: The processing module is also configured to evaluate the real-time performance of the analog signal transmission based on the demodulation delay and the filtering delay.

15. A frequency converter, characterized in that: Comprising the analog signal transmission system as described in any one of claims 1-14.

16. An analog signal transmission method performed by the analog signal transmission system according to any one of claims 1 to 14, characterized in that: include: A PWM wave generation module is used to receive the analog signal to be transmitted, and a PWM wave signal is generated based on the analog signal to be transmitted; Adopting an isolation transmission module to receive the PWM wave signal, and performing isolation transmission on the PWM wave signal; and Using a processing module to receive the PWM wave from the output end of the isolation transmission module and demodulate it to restore the analog signal, including: The processing module is used to determine the pulse width duty cycle and its timing of the PWM wave signal based on the machine cycle; based on the duty cycle and its timing, the analog signal is restored; The processing module is used to adjust the density of the time sequence based on a sampling method or a time sequence harmonization method.

17. A computer-readable storage medium, characterized in that: The device comprises computer executable instructions stored thereon, which implement the analog signal transmission method according to claim 16 when executed by a processor.

Images