A constant amplitude digital-to-rotation angle converter and a method of operation thereof

Abstract

The application relates to a constant-amplitude digital-axial angle converter and a working method thereof. The digital-axial angle converter comprises a zero-crossing comparator, a sine function generator, an angle value register, an angle operation unit, a first multiplier unit, a second multiplier unit, a first digital-analog converter and a second digital-analog converter. The constant-amplitude digital-axial angle converter has no correlation in amplitude between an input reference signal and an output coupling signal, realizes isolation of signal acquisition and signal transmission, guarantees signal transmission, adopts a digital mode to realize the digital-axial angle converter, and improves an analog angle change rate. The application reduces the demand for an analog multiplier, uses more general digital components, reduces cost, reduces an effective link, and greatly improves a digital operation rate by using a table lookup method to calculate sine and cosine values.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital-to-synthetic axis converter, and particularly relates to a constant amplitude digital-to-synthetic axis converter and a working method thereof. BACKGROUND

[0002] The digital-to-synthetic axis converter (DSAC) is a device for converting digital signals into analog angle signals, and belongs to a digital-to-analog conversion circuit. The digital-to-synthetic axis converter is used for coupling and converting an angle value input represented by binary digital quantity with a magnetizing signal into an analog signal output in the form of a rotary transformer, and has a wide application in the fields of aerospace, aviation, shipbuilding and weaponry, and provides a high-reliability angle signal transmission mode.

[0003] The existing digital-to-synthetic axis converter mainly uses a quadrant division plus arc fitting mathematical method to calculate the sine and cosine angle values, and then realizes the coupling of the sine and cosine angle values with the magnetizing signal by using a multiplication DAC device. The signal output precision depends on the precision of the quadrant division and the bit number of the multiplication DAC. However, the precision of the quadrant division directly affects the quality of the final output signal. In order to obtain higher precision, the quadrant needs to be divided more finely, which increases the hardware complexity and cost. Especially, the quadrant division circuit structure is complex, and the more the division precision is high, the larger the circuit size is, which brings many difficulties to the miniaturization of the circuit. With the improvement of the division precision, the electronic circuit used to realize these functions also becomes larger and more complex, which is a challenge for the pursuit of miniaturized design. The resolution of the multiplication DAC itself also limits the precision of the output signal. Although a high-resolution DAC can provide better performance, it also faces the problems of cost and complexity.

[0004] Therefore, in order to solve the problems in the prior art, it is urgent to realize a constant amplitude digital-to-synthetic axis converter. SUMMARY

[0005] The present application aims to provide a constant amplitude digital-to-synthetic axis converter and a working method thereof, which can solve the problems in the prior art, realize the digital-to-synthetic axis converter in a digital manner, improve the analog angle change rate and the analog axis angle signal precision, and reduce the cost and complexity.

[0006] To achieve the above object, the present application adopts the following technical scheme:

[0007] A constant amplitude digital-to-synthetic axis converter, which comprises a zero-crossing comparator, a sine function generator, an angle value register, an angle operation unit, a first multiplier unit, a second multiplier unit, a first digital-to-analog converter and a second digital-to-analog converter.

[0008] The positive input end of the zero-crossing comparator is connected with a reference signal, the negative input end is connected with the ground, and the output end is connected with the input end of the sine function generator.

[0009] The output end of the sine function generator is connected with the first input end of the first multiplier unit and the second multiplier unit respectively.

[0010] The input end of the angle value register is connected with a binary digital angle quantity, and the output end is connected with the angle operation unit.

[0011] The output end of the angle operation unit is connected with the second input end of the first multiplier unit and the second multiplier unit respectively.

[0012] The output end of the first multiplier unit is connected with the input end of the first digital-analog converter, and the output end of the second multiplier unit is connected with the input end of the first digital-analog converter.

[0013] Further, the digital-axis angle converter uses a general-purpose FPGA as a digital processing core unit; the sine function generator, the angle value register, the angle operation unit, the first multiplier unit and the second multiplier unit constitute the FPGA.

[0014] Further, the zero-crossing comparator is used for detecting the zero-crossing condition of the reference signal to calculate the period.

[0015] Further, the sine function generator is used for generating a discrete sine signal, and the discrete sine signal is used for coupling with the angle value operation.

[0016] Further, the angle value register is used for temporarily storing the input binary digital angle quantity.

[0017] Further, the angle operation unit is used for calculating the corresponding sine and cosine values of the angle by using a lookup table operation mode.

[0018] Further, the first multiplier unit is used for realizing the multiplication operation of the sine value and the discrete sine signal, and the second multiplier unit is used for realizing the multiplication operation of the cosine value and the discrete sine signal.

[0019] Further, the first digital-analog converter and the second digital-analog converter are both used for converting the digital multiplication result into an analog axis angle signal.

[0020] The application also includes a working method of the amplitude-fixed digital-axis angle converter, and the method comprises the following steps:

[0021] S1, reference signal processing

[0022] The reference signal is input to a zero-crossing comparator, the zero-crossing comparator detects the zero-crossing point of the reference signal, and based on the output result of the zero-crossing comparator, the period t of the reference signal is determined.

[0023] S2, discrete sine signal generation

[0024] The sine function generator outputs a discrete sine signal sin(ωt+φ) with the same period as the reference signal.

[0025] S3, angle value registration

[0026] The binary digital angle θ is input to the angle value register, and the angle value is temporarily stored in the angle value register.

[0027] S4, angle operation

[0028] The angle value register inputs the angle value stored therein to the angle operation unit according to the set refresh time, and the angle operation unit uses a lookup table operation method to query the sine value sinθ and the cosine value cosθ corresponding to the angle value.

[0029] S5, digital domain angle and signal coupling

[0030] The sine value sinθ and the cosine value cosθ calculated by the angle operation unit are respectively sent to the first multiplier unit and the second multiplier unit, the sine value sinθ is multiplied by the discrete sine signal sin(ωt+φ) by using the first multiplier unit, and the cosine value cosθ is multiplied by the discrete sine signal sin(ωt+φ) by using the second multiplier unit, so as to obtain two coupled sine value multiplication results.

[0031] S6, analog shaft angle signal generation

[0032] The two coupled sine value multiplication results are respectively sent to the first digital-to-analog converter and the second digital-to-analog converter, and after digital-to-analog conversion by the two digital-to-analog converters, the analog shaft angle signal synthesized by the digital angle θ and the reference signal is obtained.

[0033] Further, the signal output frequency of the sine function generator is 20MHz.

[0034] Compared with the prior art, the advantages of the present application are:

[0035] (1) The amplitude fixed digital-to-axial angle converter has no correlation between the input reference signal and the output coupled signal in amplitude, realizes isolation of signal acquisition and signal transmission, and plays a guarantee role for signal transmission. The amplitude fixed digital-to-axial angle converter is realized in a digital manner, analog angle change rate and analog axial angle signal precision are improved. The demand for analog multipliers is reduced, more general digital components are used, cost is reduced, and the digital operation rate is greatly improved by using the table lookup method to calculate the sine and cosine values.

[0036] (2) The output analog signal of the existing DRC product is a coupled signal of the excitation signal and the angle signal. If the excitation signal amplitude is very low, the output analog signal precision is limited. The amplitude fixed digital-to-axial angle converter of the application only retains phase information and ignores amplitude information by taking the external excitation signal as a reference time sequence, and then generates a sine signal with a fixed amplitude in the product, and the angle signal is coupled and output. The product structure is simple, and the output precision is stable. The problem solved by the application is mainly the precision problem, which ensures high-precision output under the condition that the excitation signal is not ideal. Since the excitation signal itself is no longer coupled, the overall design becomes simpler.

[0037] (3) The amplitude fixed digital-to-axial angle converter realizes the function of fixed amplitude, and such a product with fixed amplitude does not exist on the market. In most cases (especially in ship, aviation equipment command system), the applicability of the amplitude fixed digital-to-axial angle converter is stronger than that of the traditional product, because the amplitude is determined, and the subsequent circuit can be better adapted. The application adopts a simplified design scheme, which reduces the complexity of the whole product, thereby improving the reliability of the product. The previous products are all analog signal processing and approximation, and the application uses digital signals for direct processing. With the continuous development of DAC technology, the amplitude fixed digital-to-axial angle converter can directly realize the improvement of precision, which provides a general design scheme to meet the increasing application requirements in the future. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the principle block diagram of the amplitude fixed digital-to-axial angle converter in the application;

[0039] Figure 2 is the method flow chart of the working method of the amplitude fixed digital-to-axial angle converter in the application.

[0040] Among them:

[0041] 1. Zero-crossing comparator; 2. Sine function generator; 3. Angle value register; 4. Angle operation unit; 5. First multiplier unit; 6. Second multiplier unit; 7. First digital-to-analog converter; 8. Second digital-to-analog converter. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings:

[0043] like Figure 1 The diagram illustrates a fixed-amplitude digital-to-axis-angle converter (D-AOP) that uses a general-purpose FPGA as its core digital processing unit. The D-AOP includes a zero-crossing comparator 1, a sine function generator 2, an angle value register 3, an angle arithmetic unit 4, a first multiplier unit 5, a second multiplier unit 6, a first digital-to-analog converter 7, and a second digital-to-analog converter 8. The sine function generator 2, angle value register 3, angle arithmetic unit 4, first multiplier unit 5, and second multiplier unit 6 form the FPGA.

[0044] The fixed-amplitude digital-to-axis-angle converter described in this invention utilizes the programmability of an FPGA to construct the entire signal processing flow for digital-to-axis-angle conversion. All components work collaboratively, from reference signal processing to angle value input, calculation, and final analog signal output. By using a general-purpose FPGA to build the system core, it offers greater flexibility and scalability compared to traditional dedicated circuit architectures.

[0045] The FPGA serves as the core, allowing for flexible programming to implement various functional logics. Zero-crossing comparator 1 detects the zero-crossing of the reference signal for subsequent calculation cycles. Sine function generator 2 generates a discrete sine signal, which is used for coupling with angle value calculations. Angle value register 3 temporarily stores the input binary digital angle value. Angle calculation unit 4 calculates the corresponding sine and cosine values ​​of the angle. First multiplier unit 5 performs multiplication of the sine value with the discrete sine signal. Second multiplier unit 6 performs multiplication of the cosine value with the discrete sine signal. First digital-to-analog converter 7 and second digital-to-analog converter 8 both convert the digital multiplication results into analog axis angle signals.

[0046] like Figure 2 As shown, the present invention also includes a method for operating the above-mentioned fixed-amplitude digital-to-axis-angle converter, the method comprising the following steps:

[0047] S1, Reference Signal Processing

[0048] The reference signal is input to zero-crossing comparator 1. Zero-crossing comparator 1 detects the zero-crossing point of the reference signal. Based on the output of zero-crossing comparator 1, the period t of the reference signal is determined.

[0049] In the embodiment, the output signal of the zero-crossing comparator 1 is input to the IO pin of the FPGA chip, the FPGA acquires the falling edge of the output signal of the zero-crossing comparator 1 and calculates the time interval of adjacent falling edges, and the time interval is taken as the period t. When the sine wave signal passes through the zero-crossing point, the output state of the zero-crossing comparator 1 is flipped. The flipping can be captured by the FPGA to determine the signal period. By capturing the zero-crossing point instead of directly measuring the signal amplitude, the dependence on the signal strength is avoided, the signal processing is simplified, the robustness of the system is improved, and the error caused by the change of the signal amplitude is reduced. The above design eliminates the error caused by the transmission process of the reference signal from the method level, and eliminates the influence of the low reference signal amplitude on the accuracy of the output signal.

[0050] S2, discrete sine signal generation

[0051] The sine function generator 2 outputs a discrete sine signal sin(ωt+φ) with the same period as the reference signal.

[0052] The sine function generator 2 is used to generate a discrete sine wave synchronized with the reference signal. Based on the high-speed clock inside the FPGA, a sine wave with a pre-set frequency (for example, 20 MHz) is generated, and the waveform data can be pre-stored in a lookup table.

[0053] Since the reference signal used in engineering is mostly a sine signal with a frequency of 400 Hz to 20 kHz, a period unit sine signal is divided into 1000 points and written into the FPGA chip to sufficiently ensure the accuracy of the signal. Therefore, the signal output frequency of the sine function generator 2 is set to 20 MHz. In this way, the sine function generator 2 outputs a discrete sine signal sin(ωt+φ) with the same period as the reference signal, which fluctuates with the period fluctuation of the reference signal and does not change with the amplitude change of the reference signal. Using the digital sine wave generator, the period of the output signal of the sine function generator 2 can be ensured to be consistent with the reference signal, but is not affected by the amplitude, so that the stability of the output signal can be ensured to be improved.

[0054] In steps S1 and S2, the zero-crossing comparator 1 can accurately capture the key node of the period change of the signal, the signal level change is detected by using the comparison function of the zero-crossing comparator 1, the period is obtained by the FPGA through the measurement of the falling edge time interval, and the parameters of the sine function generator are set according to the period to generate a discrete sine signal with the same period. Through the above design, the period of the reference signal can be accurately determined, so that a discrete sine signal matched with the reference signal is generated for subsequent angle coupling calculation.

[0055] Different from the traditional analog circuit processing reference signal mode, the application accurately acquires the reference signal period and generates the corresponding discrete sine signal through digitalization. The digital processing of the reference signal period is more accurate, and the generation of the discrete sine signal facilitates subsequent digital operation and is not affected by the characteristic drift of analog circuit elements.

[0056] S3, angle value register

[0057] The binary digital angle value θ is input into the angle value register 3, and the angle value is temporarily stored in the angle value register 3.

[0058] The existing DRC product uses analog devices to calculate the angle value, and the data refresh time is mostly 20ms, which limits the simulation range of the output signal rotation speed. In the application, the angle value register 3 can ensure the temporary storage and stable input of the angle data. The angle register 3 in the FPGA is used for temporarily storing the digital angle value, and the refresh frequency and refresh time of the register can be configured by the FPGA chip according to the needs. Since the main frequency of the FPGA chip used in the application is 800MHz, the subsequent operation time is expected to be 100ns, so the refresh time of the angle value register 3 can be designed to be any value greater than 100ns. By configuring the refresh time, the speed of angle update can be adjusted according to the application requirements, so as to flexibly adjust the system response speed.

[0059] S4, angle operation

[0060] The angle value register 3 inputs the angle value stored therein into the angle operation unit 4 according to the set refresh time, and the angle operation unit 4 uses a lookup table operation mode to query the sine value sinθ and the cosine value cosθ corresponding to the angle value. That is, for each angle θ value sent into the angle operation unit 4, the corresponding sinθ and cosθ values can be queried through the lookup table. The resolution of the angle θ is the same as that of the sinθ and cosθ values, and preferably, 16bit resolution is used. The lookup table operation uses the pre-stored angle and sine / cosine value correspondence to quickly obtain the result, and through the lookup table operation, the sine / cosine value can be quickly obtained, which significantly speeds up the calculation and maintains high accuracy.

[0061] S5, digital domain angle and signal coupling

[0062] The sine value sinθ and the cosine value cosθ calculated by the angle operation unit 4 are respectively sent to a first multiplier unit 5 and a second multiplier unit 6, the sine value sinθ is multiplied with the discrete sine signal sin(ωt+φ) by using the first multiplier unit 5, and the cosine value cosθ is multiplied with the discrete sine signal sin(ωt+φ) by using the second multiplier unit 6, so that two coupled sine value multiplication results are obtained. The two multiplication results carry the coupling information of the digital angle information and the reference signal, and they are fused in the digital domain, which provides a basis for subsequent conversion into an analog shaft angle signal.

[0063] The digital multiplication operation realizes the coupling of the angle information and the reference signal, and replaces the traditional analog multiplication with the digital multiplication, so that the precision and stability are improved, the dependence on high-precision analog elements is reduced, and the cost and complexity are reduced.

[0064] S6, analog shaft angle signal generation

[0065] The two coupled sine value multiplication results are respectively sent to a first digital-to-analog converter 7 and a second digital-to-analog converter 8, and after digital-to-analog conversion by the two digital-to-analog converters, an analog shaft angle signal synthesized by the digital angle θ and the reference signal is obtained. The resolution of the digital-to-analog converter DAC is consistent with the resolution of the angle θ.

[0066] The digital-to-analog converter realizes the conversion from a digital signal to an analog signal. Because in actual application, many devices (such as motor control, sensor interface, etc.) need an analog shaft angle signal to drive or receive, this step is a key link connecting the digital processing part and the actual application scene. The analog signal is convenient for transmission in the form of low frequency and high amplitude in ships and aviation equipment, and ensures the anti-interference of the core data of the angle position action.

[0067] Because the digital-to-shaft angle converter is mostly used for long-distance transmission of the angle position, different reference signal strengths have a great influence on the transmission distance and the signal transmission quality. The traditional digital-to-shaft angle converter mostly uses an analog multiplier to perform angle coupling analog, and the amplitude follows the change of the reference signal, but the present application prevents this situation, digitizes the isolation between the acquisition of the reference signal and the generation of the coupled signal, reduces the requirements of the system on components, and realizes the normalization of the signal amplitude of the digital-to-shaft angle converter.

[0068] In the prior art, there is a case of angle coupling simulation using an analog multiplier. The present application first completes the multiplication coupling operation in the digital domain, and then performs digital-to-analog conversion. This digital-digital-analog processing flow is more accurate, is less affected by the characteristics of analog circuit elements (such as temperature drift, nonlinearity, etc.), and has higher precision of analog shaft angle signals. Digital processing of the multiplication result can better control the precision of the signal. Traditional analog multipliers may be limited in precision improvement due to the performance of analog elements. The present application is more flexible in adjusting the multiplication result in the digital domain, for example, the resolution of the digital angle, the frequency of the reference signal, and other parameters can be easily modified without the need for large-scale modification of analog circuits.

[0069] In summary, the amplitude-fixed digital-shaft angle converter of the present application has an input reference signal and an output coupling signal that are not related in amplitude, achieving signal acquisition and signal transmission isolation, which safeguards signal transmission. The digital-shaft angle converter is implemented using a digital method, which improves the analog angle change rate. The present application reduces the demand for analog multipliers and uses more general digital components, reducing costs and reducing the number of vulnerable links. Directly using a lookup table to calculate sine and cosine values greatly improves the digital operation rate.

[0070] The above-described embodiments are merely preferred embodiments of the present application and do not limit the scope of the present application. Various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art without departing from the design spirit of the present application shall fall within the scope of protection of the present application as defined by the claims.

Claims

1. A fixed-amplitude digital-to-axis-angle converter, characterized in that, The digital-to-axis angle converter includes a zero-crossing comparator (1), a sine function generator (2), an angle value register (3), an angle operation unit (4), a first multiplier unit (5), a second multiplier unit (6), a first digital-to-analog converter (7), and a second digital-to-analog converter (8); The zero-crossing comparator (1) has a positive input terminal connected to a reference signal, a negative input terminal grounded, and an output terminal connected to the input terminal of the sine function generator (2). The output of the sine function generator (2) is connected to the first input of the first multiplier unit (5) and the second multiplier unit (6), respectively. The input terminal of the angle value register (3) is connected to a binary digital angle value, and the output terminal is connected to the angle calculation unit (4); The output terminal of the angle calculation unit (4) is connected to the second input terminal of the first multiplier unit (5) and the second multiplier unit (6), respectively. The output of the first multiplier unit (5) is connected to the input of the first digital-to-analog converter (7); the output of the second multiplier unit (6) is connected to the input of the first digital-to-analog converter (7).

2. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The digital-to-axis-angle converter uses a general-purpose FPGA as the core digital processing unit. The sine function generator (2), angle value register (3), angle operation unit (4), first multiplier unit (5), and second multiplier unit (6) constitute the FPGA.

3. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The zero-crossing comparator (1) is used to detect the zero-crossing of the reference signal in order to calculate the period.

4. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The sine function generator (2) is used to generate discrete sine signals, which are used to couple with angle value calculations.

5. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The angle value register (3) is used to temporarily store the input binary digital angle value.

6. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The angle calculation unit (4) is used to calculate the sine and cosine values ​​corresponding to the angle using a lookup table operation.

7. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, The first multiplier unit (5) is used to perform multiplication operations between a sine value and a discrete sine signal; The second multiplier unit (6) is used to perform multiplication operations between the cosine value and the discrete sine signal.

8. The fixed-amplitude digital-to-axis-angle converter according to claim 1, characterized in that, Both the first digital-to-analog converter (7) and the second digital-to-analog converter (8) are used to convert the digital multiplication result into an analog axis angle signal.

9. The operating method of the fixed-amplitude digital-to-axis-angle converter according to any one of claims 1 to 8, characterized in that, The method includes the following steps: S1, Reference Signal Processing The reference signal is input to the zero-crossing comparator (1). The zero-crossing comparator (1) detects the zero-crossing point of the reference signal. Based on the output of the zero-crossing comparator (1), the period t of the reference signal is determined. S2. Generation of Discrete Sine Signals The sine function generator (2) outputs a discrete sine signal sin(ωt+φ) with the same period as the reference signal; S3, Angle Value Register The binary digital angle value θ is input into the angle value register (3), and the angle value is temporarily stored in the angle value register (3); S4, Angle Calculation The angle value register (3) inputs the angle value it stores into the angle calculation unit (4) according to the set refresh time. The angle calculation unit (4) uses a lookup table operation to look up the corresponding sine value sinθ and cosine value cosθ. S5, Digital Domain Angle and Signal Coupling The angle calculation unit (4) calculates the sine value sinθ and the cosine value cosθ, and sends them to the first multiplier unit (5) and the second multiplier unit (6) respectively. The first multiplier unit (5) multiplies the sine value sinθ with the discrete sine signal sin(ωt+φ), and the second multiplier unit (6) multiplies the cosine value cosθ with the discrete sine signal sin(ωt+φ), thus obtaining the result of the multiplication of two coupled sine values. S6, Simulated Axis Angle Signal Generation The results of multiplying the two coupled sine values ​​are sent to the first digital-to-analog converter (7) and the second digital-to-analog converter (8), respectively. After digital-to-analog conversion by the two digital-to-analog converters, the analog shaft angle signal synthesized by the digital angle θ and the reference signal is obtained.

10. The operating method of the fixed-amplitude digital-to-axis-angle converter according to claim 9, characterized in that, The signal output frequency of the sine function generator (2) is 20MHz.

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