A decoding method, decoding circuit and decoding system of a resolver

Abstract

This disclosure relates to a decoding method, decoding circuit, and decoding system for a rotary transformer. The decoding method includes: converting a digital excitation signal generated by a DDS synthesizer into an analog excitation signal using a digital-to-analog converter (DAC); amplifying the analog excitation signal and inputting it to the rotary transformer; upon receiving the analog excitation signal, the rotary transformer outputs a modulation signal; the modulation signal undergoes sequential analog-to-digital conversion and phase compensation processing to obtain a coherent signal with the same frequency and phase as the analog excitation signal; peak sampling is performed on the coherent signal, and coherent demodulation and angle calculation are performed on the modulation signal output by the rotary transformer to complete the decoding of the rotary transformer. The rotary transformer decoding method proposed in this disclosure can improve the decoding accuracy of rotary transformers.

Description

Technical Field

[0001] This disclosure relates to the field of rotary transformer technology, and in particular to a decoding method, decoding circuit and decoding system for rotary transformers. Background Technology

[0002] A rotary transformer is a high-precision electromagnetic induction angle sensor that can be used to measure the angular displacement and angular velocity of a rotating object's axis. It features small size, high temperature resistance, insensitivity to the environment, simple structure, and strong anti-interference ability, and is widely used in industrial, marine, and aerospace fields.

[0003] Since the output signal of a resolver is an analog signal, it cannot be used directly. It needs to be decoded to obtain the digital value of the rotation angle information. There are generally two methods for converting the resolver output signal: one is to use a dedicated resolver decoding chip; the other is to extract the sine and cosine envelopes of the resolver output signal and then perform angle decoding to obtain the angle information. Peak sampling is typically used when extracting the envelope. Different resolvers have different excitation frequencies, so different frequency sources need to be designed according to the resolver model in the decoding system.

[0004] In resolver decoding systems, there is a phase difference between the resolver's output signal and the excitation signal. Directly using the excitation signal to control the analog-to-digital converter (ADC) for peak sampling will cause the sampling point to deviate from the peak value, resulting in a loss of decoding accuracy. Therefore, a carrier synchronization circuit is needed to generate a coherent signal with the same frequency and phase as the resolver's output signal after phase compensation, improving the accuracy of peak sampling and thus enhancing the decoding system's accuracy. However, current technologies lack carrier self-synchronization functionality; most rely on observing the phase value with an oscilloscope and then performing manual phase compensation. Furthermore, different excitation circuits need to be designed for different resolver operating frequencies, leading to poor compatibility of the decoding system.

[0005] Therefore, it is necessary to propose a solution to improve one or more problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The first aspect of this disclosure provides a method for decoding a rotary transformer, comprising the following steps:

[0008] The digital excitation signal generated by the DDS synthesizer is converted into an analog excitation signal using a digital-to-analog converter, and the analog excitation signal is amplified and then input to the rotary transformer.

[0009] After receiving the simulated excitation signal, the rotary transformer outputs a modulation signal. The modulation signal is then subjected to analog-to-digital conversion and phase compensation processing in sequence to obtain a coherent signal that is in phase and frequency with the simulated excitation signal.

[0010] Peak sampling is performed using the coherent signal, and coherent demodulation and angle calculation are performed on the modulation signal output by the rotary transformer to complete the decoding of the rotary transformer.

[0011] In an exemplary embodiment of this disclosure, the step of converting the digital excitation signal generated by the DDS synthesizer into an analog excitation signal using digital-to-analog conversion, and then amplifying the analog excitation signal before inputting it into the rotary transformer includes:

[0012] Configure the parameters of the DDS synthesizer to generate the digital excitation signal of the required frequency for the rotary transformer;

[0013] The digital excitation signal is converted from digital to analog to obtain the analog excitation signal; the analog excitation signal is then processed by differential amplification and drive amplification in sequence, and then input to the rotary transformer.

[0014] In an exemplary embodiment of this disclosure, the step of the rotary transformer outputting a modulation signal after receiving the simulated excitation signal, and sequentially performing analog-to-digital conversion and phase compensation processing on the modulation signal to obtain a coherent signal with the same frequency and phase as the simulated excitation signal includes:

[0015] After receiving the simulated excitation signal, the rotary transformer outputs a first DSB modulation signal and a second DSB modulation signal that are orthogonal to each other and have a rotation angle.

[0016] After power-on, the rotation angle is a fixed value. Both the first DSB modulation signal and the second DSB modulation signal are subjected to A / D conversion processing to obtain the first discrete resolver output signal and the second discrete resolver output signal, respectively. At the same time, the DDS synthesizer generates a first local oscillator signal with the same frequency as the first discrete resolver output signal and a second local oscillator signal with the same frequency as the second discrete resolver output signal. The first local oscillator signal and the second local oscillator signal have the same frequency and amplitude, and the phase difference is 90°.

[0017] The phase difference of the first discrete resolver output signal, the second discrete resolver output signal, the first local oscillator signal, and the second local oscillator signal is measured to obtain the phase difference between the first DSB modulation signal and the second DSB modulation signal and the analog excitation signal.

[0018] The phase difference is input as a phase compensation value to the DDS synthesizer, and the DDS synthesizer outputs a coherent signal that is in phase and frequency with the analog excitation signal.

[0019] In an exemplary embodiment of this disclosure, the expression of the first DSB modulated signal is:

[0020] Asin(wt+σ)*sin(θ) (1)

[0021] The expression for the second DSB modulated signal is:

[0022] Asin(wt+σ)*cos(θ) (2)

[0023] Where Asin(wt) represents the analog excitation signal; A represents the amplitude of the analog excitation signal; w represents the frequency of the analog excitation signal; σ represents the phase difference between the modulation signal output by the rotary transformer and the analog excitation signal caused by the rotary transformer; θ represents the rotation angle of the rotary transformer; * represents the product; and t represents time.

[0024] The expression for the first discrete resolver output signal is:

[0025] Asin(nw△T+σ)*sin(θ) (3)

[0026] The expression for the second discrete resolver output signal is:

[0027] Asin(nw△T+σ)*cos(θ) (4)

[0028] Where △T represents the sampling interval, △T=T / N; T represents the sampling period; N represents the number of samplings; and n represents the number of sampling intervals.

[0029] In an exemplary embodiment of this disclosure, the expression for the phase difference is:

[0030] σ=-artan(b / a) (5)

[0031] Where a represents the summation of the product of the first local oscillator signal and the output signal of the first discrete resolver; b represents the summation of the product of the second local oscillator signal and the output signal of the second discrete resolver.

[0032]

[0033]

[0034] Bsin(nw△t) represents the first local oscillator signal; Bcos(nw△t) represents the second local oscillator signal; B represents the amplitude of the local oscillator signal; cos(σ) represents the cosine value of the phase difference; sin(σ) represents the sine value of the phase difference; A1 represents the product of the amplitude of the analog excitation signal and the sine value of the rotation angle θ of the rotary transformer, A1=A*sin(θ).

[0035] In an exemplary embodiment of this disclosure, the steps of performing peak sampling on the coherent signal, coherent demodulating and angle calculation on the modulation signal output by the rotary transformer, and completing the decoding of the rotary transformer include:

[0036] Using the coherent signal that is in phase and frequency with the simulated excitation signal, the DDS synthesizer is controlled to generate synchronous sampling pulses, and peak sampling is performed on the first DSB modulation signal and the second DSB modulation signal to achieve coherent demodulation, thereby obtaining sine and cosine signals with rotation angles respectively. The sine and cosine signals are then processed by angle calculation to complete the decoding of the rotary transformer.

[0037] A second aspect of this disclosure provides a decoding circuit for a rotary transformer, the decoding circuit comprising:

[0038] The system comprises a DDS module, an excitation generation module, a rotary transformer module, and a carrier synchronization module connected in series to form a loop; and an angle calculation module connected to the carrier synchronization module; wherein...

[0039] The DDS module is used to generate a digital excitation signal of the frequency required by the rotary transformer module, and to transmit the digital excitation signal to the excitation generation module.

[0040] The excitation generation module is used to convert the digital excitation signal into an analog excitation signal required by the rotary transformer module; and to transmit the analog excitation signal to the rotary transformer module.

[0041] Upon receiving the analog excitation signal, the rotary transformer module outputs a modulation signal and transmits the modulation signal to the carrier synchronization module.

[0042] The carrier synchronization module is used to receive the modulation signal and perform phase compensation on the modulation signal to achieve carrier synchronization. It also controls the analog-to-digital converter to perform peak sampling on the modulation signal through coherent signal control to achieve coherent demodulation, thereby obtaining a sine signal and a cosine signal with rotation angles respectively. The sine signal and the cosine signal are both input to the angle calculation module.

[0043] The angle calculation module is used to perform angle calculation processing on the sine signal and the cosine signal.

[0044] In an exemplary embodiment of this disclosure, the excitation generation module includes a series circuit consisting of a D / A conversion submodule, a differential amplifier submodule, and a drive amplifier submodule, in sequence; wherein...

[0045] The first output terminal of the DDS module is connected to the input terminal of the D / A conversion submodule; the output terminal of the D / A conversion submodule is connected to the input terminal of the differential amplifier submodule; the output terminal of the differential amplifier submodule is connected to the input terminal of the drive amplifier submodule; and the output terminal of the drive amplifier submodule is connected to the input terminal of the rotary transformer module.

[0046] In an exemplary embodiment of this disclosure, the carrier synchronization module includes: an A / D conversion submodule and a phase difference measurement submodule; wherein, a first input terminal of the A / D conversion submodule is connected to the output terminal of the rotary transformer module; a first output terminal of the A / D conversion submodule is connected to the first input terminal of the phase difference measurement submodule; and a second output terminal of the A / D conversion submodule is connected to the input terminal of the angle calculation module.

[0047] The output terminal of the phase difference measurement submodule is connected to the first input terminal of the DDS module; the second input terminal of the phase difference measurement submodule is connected to the second output terminal of the DDS module; the second input terminal of the DDS module is connected to an external control terminal, which is used to control the frequency of the digital excitation signal; the third output terminal of the DDS module is connected to the second input terminal of the A / D conversion submodule.

[0048] A third aspect of this disclosure provides a decoding system for a rotary transformer, the decoding system comprising: a DDS module, an excitation generation module, a rotary transformer module, a carrier synchronization module, and an angle calculation module; wherein,

[0049] The DDS module, the excitation generation module, the rotary transformer module, and the carrier synchronization module are connected in series to form a loop;

[0050] The first output terminal of the carrier synchronization module is connected to the DDS module, and the second output terminal of the carrier synchronization module is connected to the angle calculation module.

[0051] This disclosure proposes a decoding method for a rotary transformer. First, a digital excitation signal is converted into an analog excitation signal, which is then amplified and input to the rotary transformer. Next, the rotary transformer outputs a modulation signal after receiving the analog excitation signal. This modulation signal undergoes analog-to-digital conversion and phase compensation processing sequentially to obtain a coherent signal with the same frequency and phase as the analog excitation signal. Finally, peak sampling is performed on the coherent signal, and coherent demodulation and angle calculation are performed on the modulation signal output by the rotary transformer to complete the decoding of the rotary transformer. This improves the decoding accuracy of the rotary transformer. Attached Figure Description

[0052] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0053] Figure 1 A schematic diagram illustrating the steps of a decoding method for a rotary transformer in an exemplary embodiment of this disclosure is shown.

[0054] Figure 2 A schematic diagram of the decoding circuit of the rotary transformer in an exemplary embodiment of this disclosure is shown;

[0055] Figure 3 A block diagram of a decoding system for a rotary transformer in an exemplary embodiment of this disclosure is shown. Detailed Implementation

[0056] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0057] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0058] This example implementation provides a method for decoding a rotary transformer, such as... Figure 1 As shown, the following steps may be included:

[0059] Step S101: Use digital-to-analog conversion to convert the digital excitation signal generated by the DDS synthesizer into an analog excitation signal, and then amplify the analog excitation signal before inputting it into the rotary transformer.

[0060] Step S102: After receiving the analog excitation signal, the rotary transformer outputs a modulation signal. The modulation signal is then subjected to analog-to-digital conversion and phase compensation processing in sequence to obtain a coherent signal that is in phase and frequency with the analog excitation signal.

[0061] Step S103: Use coherent signals to perform peak sampling, coherent demodulate and angle calculation on the modulation signal output by the rotary transformer, and complete the decoding of the rotary transformer.

[0062] The first aspect of this disclosure proposes a decoding method for a rotary transformer. First, a digital excitation signal is converted into an analog excitation signal, which is then amplified and input to the rotary transformer. Next, the rotary transformer outputs a modulation signal after receiving the analog excitation signal. This modulation signal undergoes analog-to-digital conversion and phase compensation processing sequentially to obtain a coherent signal with the same frequency and phase as the analog excitation signal. Finally, peak sampling is performed on the coherent signal, and coherent demodulation and angle calculation are performed on the modulation signal output by the rotary transformer to complete the decoding of the rotary transformer. This improves the accuracy of rotary transformer decoding.

[0063] The steps of the method described above in this example embodiment will now be explained in more detail.

[0064] Step S101 of this embodiment includes the following sub-steps:

[0065] Sub-step S1011: Configure the parameters of the DDS synthesizer to generate a digital excitation signal of the frequency required by the rotary transformer.

[0066] Sub-step S1012: Convert the digital excitation signal to an analog excitation signal by D / A conversion; after performing differential amplification and drive amplification on the analog excitation signal, input it to the rotary transformer.

[0067] Furthermore, the DDS synthesizer utilizes the Direct Digital Frequency Synthesis (DDS) algorithm, a digital synthesis technique that converts digital signals into analog signals via a D / A converter. In sub-step S1012, this process is specifically described as follows: the digital excitation signal undergoes D / A conversion to obtain an analog excitation signal. This analog excitation signal is then subjected to differential amplification and drive amplification before being input to the resolver. Since the resolver outputs an analog signal, it cannot be used directly. Therefore, decoding the resolver output signal requires subsequent steps to obtain the digital value of the rotation angle.

[0068] Step S102 of this embodiment includes the following sub-steps:

[0069] Sub-step S1021: After receiving the analog excitation signal, the rotary transformer outputs a first DSB modulation signal and a second DSB modulation signal that are orthogonal to each other and have a rotation angle.

[0070] After the analog excitation signal is transmitted to the rotary transformer, the rotary transformer will output two DSB modulated signals with rotation angles and which are orthogonal to each other, namely the first DSB modulated signal and the second DSB modulated signal. Let the analog excitation signal be Asin(wt), then the first DSB modulated signal is Asin(wt+σ)*sin(θ), and the second DSB modulated signal is Asin(wt+σ)*cos(θ).

[0071] Sub-step S1022: After power-on, the rotation angle is a fixed value. The first DSB modulation signal and the second DSB modulation signal are both processed by A / D conversion to obtain the first discrete resolver output signal and the second discrete resolver output signal, respectively. At the same time, the DDS synthesizer generates a first local oscillator signal with the same frequency as the first discrete resolver output signal and a second local oscillator signal with the same frequency as the second discrete resolver output signal. The first local oscillator signal and the second local oscillator signal have the same frequency and amplitude, and the phase difference is 90°.

[0072] Sub-step S1023: Perform phase difference measurement calculations on the first discrete resolver output signal, the second discrete resolver output signal, the first local oscillator signal, and the second local oscillator signal to obtain the phase difference between the first DSB modulation signal, the second DSB modulation signal, and the analog excitation signal.

[0073] Sub-step S1024: The phase difference is used as a phase compensation value and input to the DDS synthesizer, and then the DDS synthesizer outputs a coherent signal that is in phase and frequency with the analog excitation signal.

[0074] Furthermore, the expression for the first DSB modulated signal is:

[0075] Asin(wt+σ)*sin(θ) (1)

[0076] The expression for the second DSB modulated signal is:

[0077] Asin(wt+σ)*cos(θ) (2)

[0078] Where Asin(wt) represents the analog excitation signal; A represents the amplitude of the analog excitation signal; w represents the frequency of the analog excitation signal; σ represents the phase difference between the modulation signal output by the rotary transformer and the analog excitation signal caused by the rotary transformer; θ represents the rotation angle of the rotary transformer; * represents the product; and t represents time.

[0079] Furthermore, the expression for the first discrete resolver output signal is:

[0080] Asin(nw△T+σ)*sin(θ) (3)

[0081] The expression for the output signal of the second discrete resolver is:

[0082] Asin(nw△T+σ)*cos(θ) (4)

[0083] Where △T represents the ADC sampling interval, △T=T / N; T represents the ADC sampling period; N represents the number of ADC samplings; and n represents the number of ADC sampling intervals.

[0084] Furthermore, the expression for the phase difference is:

[0085] σ=-artan(b / a) (5)

[0086] Where a represents the summation of the product of the first local oscillator signal and the output signal of the first discrete resolver; b represents the summation of the product of the second local oscillator signal and the output signal of the second discrete resolver.

[0087]

[0088]

[0089] Bsin(nw△t) represents the first local oscillator signal; Bcos(nw△t) represents the second local oscillator signal; B represents the amplitude of the local oscillator signal; cos(σ) represents the cosine value of the phase difference; sin(σ) represents the sine value of the phase difference; A1 represents the product of the amplitude of the analog excitation signal and the sine value of the rotation angle θ of the rotary transformer, A1=A*sin(θ).

[0090] Here, the use of the second discrete resolver output signal is similar to that of the first discrete resolver output signal, because the phase difference between the two and the analog excitation signal is the same, so only one signal needs to be measured.

[0091] Step S103 of this embodiment includes using a coherent signal that is in phase and frequency with the analog excitation signal to control the DDS synthesizer to generate a synchronous sampling pulse, perform peak sampling on the first DSB modulation signal and the second DSB modulation signal to achieve coherent demodulation, obtain two sine signals and cosine signals with rotation angles respectively, and perform angle calculation processing on the sine signals and cosine signals to complete the decoding of the rotary transformer.

[0092] The second aspect of this exemplary embodiment provides a decoding circuit for a rotary transformer, such as... Figure 2 As shown, the decoding circuit includes:

[0093] The circuit consists of a DDS module, an excitation generation module, a rotary transformer module, and a carrier synchronization module connected in series to form a loop; and an angle calculation module connected to the carrier synchronization module.

[0094] The DDS module is used to generate a digital excitation signal of the frequency required by the rotary transformer module and transmits the digital excitation signal to the excitation generation module.

[0095] The excitation generation module is used to convert digital excitation signals into analog excitation signals required by the rotary transformer module; and to transmit the analog excitation signals to the rotary transformer module.

[0096] The rotary transformer module outputs a modulation signal after receiving the analog excitation signal and transmits the modulation signal to the carrier synchronization module.

[0097] The carrier synchronization module is used to receive the modulated signal and perform phase compensation on the modulated signal to achieve carrier synchronization. It also controls the analog-to-digital converter to perform peak sampling on the modulated signal through coherent signal to achieve coherent demodulation, thereby obtaining sine and cosine signals with rotation angles. Both sine and cosine signals are then input to the angle calculation module.

[0098] The angle calculation module is used to perform angle calculation processing on sine and cosine signals.

[0099] Furthermore, the excitation generation module includes a series circuit consisting of a D / A conversion submodule, a differential amplifier submodule, and a drive amplifier submodule; wherein,

[0100] The first output terminal of the DDS module is connected to the input terminal of the D / A conversion submodule; the output terminal of the D / A conversion submodule is connected to the input terminal of the differential amplifier submodule; the output terminal of the differential amplifier submodule is connected to the input terminal of the drive amplifier submodule; and the output terminal of the drive amplifier submodule is connected to the input terminal of the rotary transformer module.

[0101] Furthermore, the carrier synchronization module includes an A / D conversion submodule and a phase difference measurement submodule, wherein the first input terminal of the A / D conversion submodule is connected to the output terminal of the rotary transformer module; the first output terminal of the A / D conversion submodule is connected to the first input terminal of the phase difference measurement submodule; and the second output terminal of the A / D conversion submodule is connected to the input terminal of the angle calculation module.

[0102] The output of the phase difference measurement submodule is connected to the first input of the DDS module; the second input of the phase difference measurement submodule is connected to the second output of the DDS module; the second input of the DDS module is connected to an external control terminal, which is used to control the frequency of the digital excitation signal; and the third output of the DDS module is connected to the second input of the A / D conversion submodule.

[0103] like Figure 2 As shown, the digital correlation operations of the DDS submodule and the phase difference submodule are implemented using an FPGA. The D / A conversion submodule performs digital-to-analog conversion using a high-precision DAC chip, then processes the digital excitation signal using a differential amplifier submodule, and improves the driving capability of the digital excitation signal using a drive amplifier submodule. The differential amplifier submodule contains a differential amplifier. The drive amplifier submodule contains a drive amplifier.

[0104] The A / D conversion submodule uses a high-precision ADC chip to acquire and convert the modulation signal output from the rotary transformer into an analog-to-digital signal.

[0105] It should also be noted that, in Figure 2 In this circuit, the circuit between the DDS module and the D / A conversion submodule is a multi-bit circuit, and the circuit between the DDS module and the external control terminal is also a multi-bit circuit.

[0106] The third aspect of this exemplary implementation provides a decoding system for a rotary transformer, such as... Figure 3 As shown, the decoding system includes: an excitation generation module, a rotary transformer module, a carrier synchronization module, an angle calculation module, and a DDS module; among which,

[0107] The DDS module, excitation generation module, rotary transformer module and carrier synchronization module are connected in series to form a loop;

[0108] The first output of the carrier synchronization module is connected to the DDS module, and the second output of the carrier synchronization module is connected to the angle calculation module.

[0109] It should be noted that although several units of the system for executing actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of two or more units described above can be further divided and embodied by multiple units. Some or all of the units can be selected to achieve the purpose of this disclosure according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

[0110] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A decoding method for a rotary transformer, characterized in that, Includes the following steps: The digital excitation signal generated by the DDS synthesizer is converted into an analog excitation signal using a digital-to-analog converter, and the analog excitation signal is amplified and then input to the rotary transformer. After receiving the simulated excitation signal, the rotary transformer outputs a modulation signal. The modulation signal is then subjected to analog-to-digital conversion and phase compensation processing to obtain a coherent signal that is in phase and frequency with the simulated excitation signal. The rotary transformer also outputs a first DSB modulation signal and a second DSB modulation signal that are orthogonal to each other and have a rotation angle after receiving the simulated excitation signal. After power-on, the rotation angle is a fixed value. Both the first DSB modulation signal and the second DSB modulation signal are subjected to A / D conversion processing to obtain the first discrete resolver output signal and the second discrete resolver output signal, respectively. At the same time, the DDS synthesizer generates a first local oscillator signal with the same frequency as the first discrete resolver output signal and a second local oscillator signal with the same frequency as the second discrete resolver output signal. The first local oscillator signal and the second local oscillator signal have the same frequency and amplitude, and the phase difference is 90°. The phase difference of the first discrete resolver output signal, the second discrete resolver output signal, the first local oscillator signal, and the second local oscillator signal is measured to obtain the phase difference between the first DSB modulation signal and the second DSB modulation signal and the analog excitation signal. The phase difference is input as a phase compensation value to the DDS synthesizer, and the DDS synthesizer outputs the coherent signal that is in phase and frequency with the analog excitation signal. Peak sampling is performed on the coherent signal to coherently demodulate and calculate the angle of the modulation signal output by the rotary transformer, thus completing the decoding of the rotary transformer. Specifically, the coherent signal, which is in phase and frequency with the analog excitation signal, is used to control the DDS synthesizer to generate synchronous sampling pulses. Peak sampling is performed on the first DSB modulation signal and the second DSB modulation signal to achieve coherent demodulation, obtaining sine and cosine signals with rotation angles respectively. The sine and cosine signals are then processed for angle calculation to complete the decoding of the rotary transformer.

2. The decoding method for a rotary transformer according to claim 1, characterized in that, The step of converting the digital excitation signal generated by the DDS synthesizer into an analog excitation signal using digital-to-analog conversion, and then amplifying the analog excitation signal before inputting it into the rotary transformer includes: Configure the parameters of the DDS synthesizer to generate the digital excitation signal of the required frequency for the rotary transformer; The digital excitation signal is converted from digital to analog to obtain the analog excitation signal; the analog excitation signal is then processed by differential amplification and drive amplification in sequence, and then input to the rotary transformer.

3. The decoding method for a rotary transformer according to claim 1, characterized in that, The expression for the first DSB modulated signal is: （1） The expression for the second DSB modulated signal is: （2） in, This represents the analog excitation signal; A represents the amplitude of the analog excitation signal. w Indicates the frequency of the simulated excitation signal; This indicates the phase difference between the modulated signal output by the rotary transformer and the analog excitation signal caused by the rotary transformer. Indicates the rotation angle of the rotary transformer; The product is represented by t; time is represented by t. The expression for the first discrete resolver output signal is: （3） The expression for the second discrete resolver output signal is: （4） in, Indicates the sampling interval. T represents the sampling period; N represents the number of samples. Indicates the number of sampling intervals.

4. The decoding method for a rotary transformer according to claim 3, characterized in that, The expression for the phase difference is: （5） Where a represents the summation of the product of the first local oscillator signal and the output signal of the first discrete resolver; b represents the summation of the product of the second local oscillator signal and the output signal of the second discrete resolver. ， ； Indicates the first local oscillator signal; B represents the second local oscillator signal; B represents the amplitude of the local oscillator signal. The cosine value representing the phase difference; A1 represents the sine value of the phase difference; A1 represents the amplitude of the analog excitation signal and the rotation angle of the rotary transformer. The product of the sine values, .

5. A decoding circuit for a rotary transformer, characterized in that, For performing the decoding method of the rotary transformer as described in any one of claims 1-4, the decoding circuit includes: The circuit consists of a DDS module, an excitation generation module, a rotary transformer module, and a carrier synchronization module connected in series to form a loop; and an angle calculation module connected to the carrier synchronization module. The DDS module is used to generate a digital excitation signal of the frequency required by the rotary transformer module, and to transmit the digital excitation signal to the excitation generation module. The excitation generation module is used to convert the digital excitation signal into an analog excitation signal required by the rotary transformer module; and to transmit the analog excitation signal to the rotary transformer module. Upon receiving the analog excitation signal, the rotary transformer module outputs a modulation signal and transmits the modulation signal to the carrier synchronization module. The carrier synchronization module is used to receive the modulation signal and perform phase compensation on the modulation signal to achieve carrier synchronization. It also controls the analog-to-digital converter to perform peak sampling on the modulation signal through coherent signal control to achieve coherent demodulation, thereby obtaining a sine signal and a cosine signal with rotation angles respectively. The sine signal and the cosine signal are both input to the angle calculation module. The carrier synchronization module includes: The A / D conversion submodule has its first input terminal connected to the output terminal of the rotary transformer module; the first output terminal of the A / D conversion submodule is connected to the first input terminal of the phase difference measurement submodule. The output terminal of the phase difference measurement submodule is connected to the first input terminal of the DDS module; the second input terminal of the DDS module is connected to an external control terminal, which is used to control the frequency of the digital excitation signal. The second output terminal of the DDS module is connected to the second input terminal of the phase difference measurement submodule; the third output terminal of the DDS module is connected to the second input terminal of the A / D conversion submodule. The second output terminal of the A / D conversion submodule is connected to the input terminal of the angle calculation module; The angle calculation module is used to perform angle calculation processing on the sine signal and the cosine signal.

6. The decoding circuit for the rotary transformer according to claim 5, characterized in that, The excitation generation module includes a series circuit consisting of a D / A conversion submodule, a differential amplifier submodule, and a drive amplifier submodule; wherein, The first output terminal of the DDS module is connected to the input terminal of the D / A conversion submodule; the output terminal of the D / A conversion submodule is connected to the input terminal of the differential amplifier submodule; the output terminal of the differential amplifier submodule is connected to the input terminal of the drive amplifier submodule; and the output terminal of the drive amplifier submodule is connected to the input terminal of the rotary transformer module.

7. A decoding system for a rotary transformer, characterized in that, For executing the decoding method of the rotary transformer as described in any one of claims 1-4, the decoding system comprises: a DDS module, an excitation generation module, a rotary transformer module, a carrier synchronization module, and an angle calculation module; wherein, The DDS module, the excitation generation module, the rotary transformer module, and the carrier synchronization module are connected in series to form a loop; The first output terminal of the carrier synchronization module is connected to the DDS module, and the second output terminal of the carrier synchronization module is connected to the angle calculation module.

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