Electronic SCOTT conversion circuit

Abstract

The invention relates to an electronic SCOTT conversion circuit. The circuit comprises a summing circuit, a subtraction circuit and an alternating current signal voltage reduction circuit. The summing circuit is used for calculating the sum of the SIN signal and the COS signal and outputting an S1 signal. And the alternating current signal voltage reduction circuit is used for performing proportion reduction on the COS signal, performing equal proportion reversing after the proportion of the COS signal is reduced, and outputting an S2 signal. And the subtraction circuit is used for calculating the difference between the SIN signal and the COS signal and outputting an S3 signal. According to the electronic SCOTT conversion circuit, the defects in the prior art can be overcome, and compared with a conventional SCOTT transformer, the size of the electronic SCOTT conversion circuit is greatly reduced, the circuit structure is simple, and the conversion frequency range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of digital / shaft angle converters, and in particular to an electronic SCOTT conversion circuit for a digital / self-synchronous angle machine converter. Background Art

[0002] The digital / auto-synchro converter is used in the shaft angle servo control system. Its function is to convert the input binary digital angle signal into a three-phase auto-synchro analog angle signal, and the phase difference between any two phases is 120°. The circuit principle framework of the digital / auto-synchro converter is: first, the input digital signal is converted into a three-phase auto-synchro analog angle signal through a high-precision sine and cosine function generator circuit. Figure 1 The orthogonal sine and cosine signals shown in the figure are then transformed by SCOTT to produce the following output: Figure 2 The three-phase synchro shown simulates an angle signal.

[0003] At present, the conventional SCOTT transformation is carried out through a SCOTT transformer. The SCOTT transformer is a special transformer with two primary sides. The principle of the SCOTT transformer is as follows: Figure 3 As shown. Figure 3 It can be seen that the SIN and COS of the primary side of the SCOTT transformer are input signals, and the secondary side S1, S2, and S3 are the output three-phase signals. Then, since the conventional SCOTT transformer is wound by coils, the lower the signal frequency, the more coil turns, and the larger the size. Moreover, when the operating frequency changes, the transformer needs to be rewound, which is very unfavorable for platform design and cannot meet the requirements of lightweight and miniaturization of modern equipment.

[0004] Therefore, in order to solve the above problems, it is urgent to realize an electronic SCOTT conversion circuit. Summary of the invention

[0005] The object of the present invention is to provide an electronic SCOTT conversion circuit, which can solve the deficiencies in the prior art. Compared with a conventional SCOTT transformer, the electronic SCOTT conversion circuit has a greatly reduced volume, a simple circuit structure and a wide conversion frequency range.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] An electronic SCOTT conversion circuit comprises an adding circuit, a subtracting circuit and an AC signal voltage reducing circuit.

[0008] The adding circuit is used to calculate the sum of the SIN signal and the COS signal and output the S1 signal.

[0009] The AC signal voltage reduction circuit is used to proportionally reduce the COS signal, and then perform proportional inversion after the COS signal is proportionally reduced to output the S2 signal.

[0010] The subtraction circuit is used to calculate the difference between the SIN signal and the COS signal and output the S3 signal.

[0011] Preferably according to the present invention, the adding circuit includes a single operational amplifier N1, a resistor R1, a resistor R2 and a resistor R3.

[0012] The non-inverting input terminal of the single operational amplifier N1 is grounded, and the inverting input terminal of the single operational amplifier N1 is respectively connected to the first end of the resistor R1, the first end of the resistor R2, and the first end of the resistor R3; the second end of the resistor R1 is connected to the SIN signal; the second end of the resistor R2 is connected to the COS signal; the second end of the resistor R3 is connected to the output terminal of the single operational amplifier N1; and the output terminal of the single operational amplifier N1 outputs the S1 signal.

[0013] Preferably according to the present invention, the AC signal voltage reduction circuit includes a dual operational amplifier, a resistor R4, a resistor R5, a resistor R6 and a resistor R7.

[0014] The dual operational amplifier includes a single operational amplifier N2 and a single operational amplifier N3; the inverting input terminal of the single operational amplifier N2 is connected to the first end of the resistor R5, and the second end of the resistor R5 is connected to the COS signal; the non-inverting input terminals of the single operational amplifier N2 and the single operational amplifier N3 are both grounded, the output terminal of the single operational amplifier N2 is connected to the first end of the resistor R6, and the second end of the resistor R6 is connected to the inverting input terminal of the single operational amplifier N3; the first end of the resistor R4 is connected to the inverting input terminal of the single operational amplifier N2, and the second end of the resistor R4 is connected to the output terminal of the single operational amplifier N2; the first end of the resistor R7 is connected to the inverting input terminal of the single operational amplifier N3, and the second end of the resistor R7 is connected to the output terminal of the single operational amplifier N3; the output terminal of the single operational amplifier N3 outputs the S2 signal.

[0015] Preferably according to the present invention, the subtraction circuit includes a single operational amplifier N4, a resistor R8, a resistor R9 and a resistor R10; the in-phase input terminal of the single operational amplifier N4 is connected to the first end of the resistor R8, and the second end of the resistor R8 is connected to the SIN signal; the inverting input terminal of the single operational amplifier N4 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the COS signal; the first end of the resistor R10 is connected to the inverting input terminal of the single operational amplifier N4, and the second end of the resistor R10 is connected to the output terminal of the single operational amplifier N4; the output terminal of the single operational amplifier N4 outputs the S3 signal.

[0016] Preferably according to the present invention, the resistors R1 , R2 , R3 , R4 , R5 , R6 , R7 , R8 , R9 and R10 are all thin film resistors.

[0017] Preferably according to the present invention, the resistor R1 and the resistor R2 are precision resistors; and the resistor R3 is a feedback resistor.

[0018] Preferably, according to the present invention, the resistance relationship among the resistor R1, the resistor R2 and the resistor R3 is:

[0019]

[0020] Preferably according to the present invention, the resistor R4 is a feedback resistor, and the resistor R5 is a precision resistor.

[0021] Preferably, according to the present invention, the relationship between the resistor R4 and the resistor R5 is: The resistance values ​​of the resistor R6 and the resistor R7 are equal.

[0022] Preferably, according to the present invention, the resistor R10 is a feedback resistor; the resistance relationship among the resistor R8, the resistor R9 and the resistor R10 is:

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] The electronic SCOTT conversion circuit of the present invention obtains the three-phase signals S1, S2, and S3 by calculating through an operational amplifier and a thin-film resistor network, which can save the bulky coil transformer and greatly reduce the size and weight of the system. The present invention designs and selects a wide-band operational amplifier, and when the operating frequency of the digital / self-synchronous machine converter changes, there is no need to rewind the transformer like the traditional SCOTT conversion, which is conducive to platform design. The operating frequency range of the electronic SCOTT conversion circuit of the present invention can be increased from a single frequency to 50Hz to 20kHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of input signal for electronic SCOTT transformation;

[0026] Figure 2 This is a schematic diagram of the output signal of the electronic SCOTT transformation;

[0027] Figure 3 This is the circuit schematic diagram of a conventional SCOTT transformer;

[0028] Figure 4 This is the electrical connection diagram for the synchro signal;

[0029] Figure 5 The electronic SCOTT conversion circuit diagram proposed by the present invention;

[0030] Figure 6 It is a 0° simulation waveform diagram of the electronic SCOTT conversion circuit in the present invention;

[0031] Figure 7 It is a 45° simulation waveform diagram of the electronic SCOTT conversion circuit in the present invention;

[0032] Figure 8 It is a 90° simulation waveform diagram of the electronic SCOTT conversion circuit in the present invention;

[0033] Fig. 9 This is a comparison chart of DSC converters designed based on different SCOTT transforms. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings:

[0035] like Figure 5 The electronic SCOTT conversion circuit shown in FIG. 1 includes an addition circuit, a subtraction circuit and an AC signal voltage reduction circuit. The electronic SCOTT conversion circuit realizes the conversion from orthogonal sine (SIN) and cosine (COS) signals to three-phase synchro signals (S1, S2, S3) through the addition circuit, the AC signal voltage reduction circuit (including proportional reduction and proportional inversion) and the subtraction circuit. The electrical connection diagram of the synchro signal is shown in FIG. Figure 4 shown.

[0036] The adding circuit is used to calculate the sum of the SIN signal and the COS signal and output the S1 signal.

[0037] The AC signal voltage reduction circuit is used to proportionally reduce the COS signal, and then proportionally reverse the COS signal after the COS signal is proportionally reduced, and output the S2 signal. The AC signal reduction circuit is connected to a proportional reverse circuit after the COS signal is proportionally reduced, and is used to keep the output signal in phase with the input signal.

[0038] The subtraction circuit is used to calculate the difference between the SIN signal and the COS signal and output the S3 signal.

[0039] The S1, S2, and S3 signals are three-phase synchro analog angle signals, which are 120 degrees apart in phase and are used to drive the three-phase synchro. The generation of these signals is achieved through an addition circuit, an AC signal voltage reduction circuit, and a subtraction circuit, each of which is responsible for generating a specific phase signal. In the SCOTT transformation circuit, the accurate generation and phase relationship of these signals are critical to ensure the correct operation of the servo control system. The S1 signal usually represents phase A in a three-phase system; the S2 signal usually represents phase B in a three-phase system, with a phase difference of 120 degrees relative to the S1 signal; the S3 signal usually represents phase C in a three-phase system, with a phase difference of 240 degrees (or -120 degrees) relative to the S1 signal. The amplitudes of the S1, S2, and S3 signals are usually the same, or are appropriately adjusted according to the specific application requirements. Ideally, the peak amplitudes of these three signals are the same, but there may be some differences in the actual circuit, depending on the accuracy of the resistors and the performance of the operational amplifier.

[0040] The addition circuit, AC signal voltage reduction circuit and subtraction circuit in the present invention are used to obtain a sinusoidal signal with a specific proportional relationship between the output amplitude and the input amplitude. The signal output frequency range depends on the bandwidth of the integrated operational amplifier, and the conversion frequency range of the SCOTT conversion circuit described in the present invention is wide.

[0041] Preferably, according to the present invention, the adding circuit comprises a single operational amplifier N1, a resistor R1, a resistor R2 and a resistor R3. The non-inverting input terminal of the single operational amplifier N1 is grounded, and the inverting input terminal of the single operational amplifier N1 is respectively connected to the first end of the resistor R1, the first end of the resistor R2 and the first end of the resistor R3; the second end of the resistor R1 is connected to the SIN signal; the second end of the resistor R2 is connected to the COS signal; the second end of the resistor R3 is connected to the output terminal of the single operational amplifier N1. The output terminal of the single operational amplifier N1 outputs the S1 signal.

[0042] Preferably, according to the present invention, the AC signal voltage reduction circuit includes a dual operational amplifier, a resistor R4, a resistor R5, a resistor R6 and a resistor R7. The dual operational amplifier includes a single operational amplifier N2 and a single operational amplifier N3. The inverting input terminal of the single operational amplifier N2 is connected to the first end of the resistor R5, and the second end of the resistor R5 is connected to the COS signal; the in-phase input terminals of the single operational amplifier N2 and the single operational amplifier N3 are both grounded, the output terminal of the single operational amplifier N2 is connected to the first end of the resistor R6, and the second end of the resistor R6 is connected to the inverting input terminal of the single operational amplifier N3; the first end of the resistor R4 is connected to the inverting input terminal of the single operational amplifier N2, and the second end of the resistor R4 is connected to the output terminal of the single operational amplifier N2; the first end of the resistor R7 is connected to the inverting input terminal of the single operational amplifier N3, and the second end of the resistor R7 is connected to the output terminal of the single operational amplifier N3. The output terminal of the single operational amplifier N3 outputs the S2 signal. The first operational amplifier N2 is used as a voltage follower or reducer to proportionally reduce the COS signal. The second operational amplifier N3 is used to invert the signal, so that the output signal can be kept in phase with the input signal. A resistor network is used between the two operational amplifiers to set the appropriate proportional factor.

[0043] Preferably, the subtraction circuit includes a single operational amplifier N4, a resistor R8, a resistor R9 and a resistor R10. The in-phase input terminal of the single operational amplifier N4 is connected to the first terminal of the resistor R8, and the second terminal of the resistor R8 is connected to the SIN signal; the inverting input terminal of the single operational amplifier N4 is connected to the first terminal of the resistor R9, and the second terminal of the resistor R9 is connected to the COS signal; the first terminal of the resistor R10 is connected to the inverting input terminal of the single operational amplifier N4, and the second terminal of the resistor R10 is connected to the output terminal of the single operational amplifier N4. The output terminal of the single operational amplifier N4 outputs the S3 signal.

[0044] Preferably according to the present invention, the resistors R1 , R2 , R3 , R4 , R5 , R6 , R7 , R8 , R9 and R10 are all thin film resistors.

[0045] Preferably, the resistor R1 and the resistor R2 are precision resistors. The resistor R3 is a feedback resistor. In the adding circuit, the SIN signal and the COS signal are connected to the inverting input terminal of the single operational amplifier N1 through the precision resistor R1 and the precision resistor R2, respectively. The output signal S1 of the adding circuit is simultaneously connected to the inverting input terminal of the single operational amplifier N1 through the feedback resistor R3 to form a closed loop. In the adding circuit, the resistance relationship among the resistors R1, R2 and R3 is: R1 / R2 / R3= This specific resistor ratio relationship affects the amplitude of the output signal S1 and the ratio relationship between the input signals SIN and COS. Through this specific resistor ratio relationship, the adding circuit can add the SIN signal and the COS signal with different weights and output the S1 signal. With this configuration, the adding circuit can effectively add the SIN signal and the COS signal to generate the S1 signal while maintaining a specific ratio relationship between the output signal and the input signal.

[0046] Preferably, according to the present invention, in the AC signal voltage reduction circuit, the resistor R4 is a feedback resistor, and the resistor R5 is a precision resistor. The COS signal is connected to the inverting input terminal of the single operational amplifier N2 through the precision resistor R5. The output terminal of the single operational amplifier N2 is connected to the inverting input terminal of the single operational amplifier N3 through the resistor R6 on the one hand, and is connected to the inverting input terminal of the single operational amplifier N2 through the feedback resistor R4, and the non-inverting input terminal of the single operational amplifier N2 is grounded; the output terminal of the single operational amplifier N3 is connected to the inverting input terminal of the single operational amplifier N3 through the resistor R7, and the non-inverting input terminal of the single operational amplifier N3 is grounded. Through the proportional relationship between the resistor R4 and the resistor R5, the single operational amplifier N2 inverts the COS signal and reduces it to about 0.588 times. Through the proportional relationship between the resistor R6 and the resistor R7, the output of the single operational amplifier N2 is inverted again and restored to the same phase as the COS signal, but the amplitude is still about 0.588 times. In the AC signal voltage reduction circuit, the relationship between the resistor R4 and the resistor R5 is: R6=R7. Through such a design, the AC signal voltage reduction circuit realizes the proportional reduction of the COS signal and keeps the same phase as the input signal. This circuit structure is very useful in SCOTT transformation because it can accurately control the amplitude and phase of the output signal to meet specific application requirements.

[0047] Preferably, in the subtraction circuit, the resistor R10 is a feedback resistor. The SIN signal is connected to the non-inverting input terminal of the single operational amplifier N4 through the resistor R8, the COS signal is connected to the reverse terminal of the single operational amplifier N4 through the resistor R9, and the output terminal of the single operational amplifier N4 is connected to the reverse terminal of the single operational amplifier N4 through the feedback resistor R10. In the subtraction circuit, the resistance relationship among the resistors R8, R9 and R10 is: Through this specific resistor ratio relationship, the subtraction circuit can accurately subtract the COS signal from the SIN signal and output the S3 signal.

[0048] Through the above circuit design, an electronic SCOTT conversion circuit with a wide frequency response range can be realized, while maintaining a specific amplitude ratio relationship between the output signal and the input signal. The electronic SCOTT conversion circuit described in the present invention has a simple and clear structure, and can realize SCOTT conversion by using integrated circuits for addition and subtraction operations. Compared with conventional transformer conversion, the volume of the circuit is greatly reduced. Moreover, for the electronic SCOTT conversion circuit proposed in the present invention, designers can design different gain coefficients by changing the ratio of peripheral operation parameters as needed, thereby realizing the output of synchro signals of various amplitudes.

[0049] Figure 6-Figure 8 It is the simulated output waveform of the electronic SCOTT conversion circuit of the present invention at 0°, 45°, and 90°. Figure 6-Figure 8 In the figure, the horizontal axis represents time in us, and the vertical axis represents amplitude in V. Figure 6-Figure 8 It can be seen that the electronic SCOTT conversion circuit described in the present invention is effective and feasible.

[0050] The present invention solves the problem of the existing SCOTT transformer having a single operating frequency and being too large in size and weight, thereby achieving the purpose and effect of miniaturization and lightness of the system. Fig. 9 The DSC converters shown in the figure are designed based on different SCOTT conversion methods. The black module on the left side of the figure is a DSC converter designed based on a SCOTT transformer. Because of the SCOTT transformer inside, the outer dimensions are large, with an outer dimension of 79.4×66.7×24mm3 and a weight of 270g. The nickel-plated metal shell product on the right side of the figure is a DSC converter designed using the electronic SCOTT conversion circuit described in the present invention. The outer dimensions are 54.36×28.96×5.08mm3 and the weight is 27g. The size is reduced to 6.3% of the original size and the weight is 10% of the original product. Fig. 9 It can be seen from the obvious comparison between the two DSC converter products that the present invention achieves the purpose and effect of miniaturization and lightweight of the system.

[0051] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the scope of protection determined by the claims of the present invention.

Claims

1. An electronic SCOTT conversion circuit, characterized in that: The circuit includes an adding circuit, a subtracting circuit and an AC signal voltage reducing circuit; The adding circuit is used to calculate the sum of the SIN signal and the COS signal and output the S1 signal; The AC signal voltage reduction circuit is used to proportionally reduce the COS signal, and then perform proportional inversion after the COS signal is proportionally reduced, and output the S2 signal; The subtraction circuit is used to calculate the difference between the SIN signal and the COS signal and output the S3 signal.

2. The electronic SCOTT conversion circuit according to claim 1, characterized in that: The adding circuit includes a single operational amplifier N1, a resistor R1, a resistor R2 and a resistor R3; The non-inverting input terminal of the single operational amplifier N1 is grounded, and the inverting input terminal of the single operational amplifier N1 is respectively connected to the first end of the resistor R1, the first end of the resistor R2, and the first end of the resistor R3; the second end of the resistor R1 is connected to the SIN signal; the second end of the resistor R2 is connected to the COS signal; the second end of the resistor R3 is connected to the output terminal of the single operational amplifier N1; and the output terminal of the single operational amplifier N1 outputs the S1 signal.

3. The electronic SCOTT conversion circuit according to claim 2, characterized in that: The AC signal voltage reduction circuit includes a dual operational amplifier, a resistor R4, a resistor R5, a resistor R6 and a resistor R7; The dual operational amplifier includes a single operational amplifier N2 and a single operational amplifier N3; the inverting input terminal of the single operational amplifier N2 is connected to the first end of the resistor R5, and the second end of the resistor R5 is connected to the COS signal; the non-inverting input terminals of the single operational amplifier N2 and the single operational amplifier N3 are both grounded, the output terminal of the single operational amplifier N2 is connected to the first end of the resistor R6, and the second end of the resistor R6 is connected to the inverting input terminal of the single operational amplifier N3; the first end of the resistor R4 is connected to the inverting input terminal of the single operational amplifier N2, and the second end of the resistor R4 is connected to the output terminal of the single operational amplifier N2; the first end of the resistor R7 is connected to the inverting input terminal of the single operational amplifier N3, and the second end of the resistor R7 is connected to the output terminal of the single operational amplifier N3; the output terminal of the single operational amplifier N3 outputs the S2 signal.

4. The electronic SCOTT conversion circuit according to claim 3, characterized in that: The subtraction circuit includes a single operational amplifier N4, a resistor R8, a resistor R9 and a resistor R10; the in-phase input terminal of the single operational amplifier N4 is connected to the first end of the resistor R8, and the second end of the resistor R8 is connected to the SIN signal; the inverting input terminal of the single operational amplifier N4 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the COS signal; the first end of the resistor R10 is connected to the inverting input terminal of the single operational amplifier N4, and the second end of the resistor R10 is connected to the output terminal of the single operational amplifier N4; the output terminal of the single operational amplifier N4 outputs the S3 signal.

5. The electronic SCOTT conversion circuit according to claim 4, characterized in that: The resistors R1 , R2 , R3 , R4 , R5 , R6 , R7 , R8 , R9 and R10 are all thin film resistors.

6. The electronic SCOTT conversion circuit according to claim 2, characterized in that: The resistor R1 and the resistor R2 are precision resistors; the resistor R3 is a feedback resistor.

7. The electronic SCOTT conversion circuit according to claim 2, characterized in that: The resistance relationship among the resistor R1, the resistor R2 and the resistor R3 is:

8. The electronic SCOTT conversion circuit according to claim 3, characterized in that: The resistor R4 is a feedback resistor, and the resistor R5 is a precision resistor.

9. The electronic SCOTT conversion circuit according to claim 3, characterized in that: The relationship between the resistor R4 and the resistor R5 is: The resistance values ​​of the resistor R6 and the resistor R7 are equal.

10. The electronic SCOTT conversion circuit according to claim 4, characterized in that: The resistor R10 is a feedback resistor; The resistance relationship among the resistor R8, the resistor R9 and the resistor R10 is:

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