JPH0240993B2 - KORYUCHOKURYUBUNRIKENSHUTSUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC/DC separation and detection device that separates and detects a DC component and an AC component from a constant frequency sine wave on which a DC component is superimposed.

FIG. 1 is a block diagram showing a conventional AC/DC separation and detection device. In Fig. 1, a constant frequency sine wave vf with a period T = 1/f (where f is a cycle) is now superimposed on the input terminal 1 with a DC voltage Vdc as shown in Fig. 1 a1 and Fig. 2 a. When the voltage is applied, the DC component removal circuit 2 removes the DC component and
It outputs an AC component vf as shown in Figure a2. This AC component vf and the input from the input terminal 1 are applied to the AC component removal circuit 3, and the AC component removal circuit 3 subtracts the output of the DC component removal circuit 2 from the input of the input terminal 1. A DC component Vdc as shown in FIG. a3 is generated at the output terminal 4.

However, this conventional DC/AC separation and detection device requires at least one cycle of the input applied to the input terminal 1 in order to separate the DC component and the AC component. Therefore, now input terminal 1
As shown in Fig. 1b1 and Fig. 2b, when the DC component of the input applied to Vdc changes stepwise to Vdc2, the DC component removal circuit 2 and the AC component removal circuit 3 each have a certain time constant. Therefore, the output of the DC component removal circuit 2 is as shown in Fig. 1 b2, and the output of the AC component removal circuit 3 is as shown in Fig. 1 b3.
As shown in FIG. 2, the DC component Vdc could not be detected at the output terminal 4 until a certain period of time related to the time constant elapsed. Furthermore, in the past, various devices other than the one shown in FIG. 1 have been devised, but all of them have the same drawback as the device shown in FIG. 1 that they require at least one input cycle or longer.

This invention has been made to eliminate the drawbacks of the prior art. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing one embodiment of the AC separation and detection device according to the present invention. Figure 4 is the third
In the waveform diagram of each part for explaining the operation of the figure, time t is plotted on the horizontal axis and voltage V is plotted on the vertical axis. In FIG. 3, a constant frequency sine wave vf with a period T=1/f (where f is a cycle) on which a DC voltage Vdc is superimposed is applied to the input terminal 11 as shown in FIG. 4, 11. The first AD conversion circuit 12 divides _the period T into _n equal parts as shown in FIG _.
...Voltages v ₀ , v ₁ , v ₂ ...vn obtained by sampling the analog quantity AC input voltage of the input terminal 11 every tn
This converts the data into a digital quantity. The first difference detection circuit 13 detects the difference between the digital quantities of the output voltage of the first AD conversion circuit 12 at the present time and the output voltage at a predetermined time before the present time, for example, the output at time _t1 . voltage v ₁
The digital quantity corresponding to the difference voltage v ₀₁ between the output voltage v ₀ and the output voltage v 0 at time t ₀ is detected. 1st
The DA conversion circuit 14 converts the digital quantity output of the first difference detection circuit 13 into an analog quantity alternating current, and obtains an output as shown in FIG. 4. 1st
The low frequency band filter 15 removes harmonic components of the analog output from the first DA conversion circuit 14 to obtain the sine wave AC output shown in FIG. The second AD conversion circuit 16 samples the analog quantity output of the first low frequency band filter 15 and converts it into a digital quantity.
As shown in FIG. 4 15', which is an enlarged view of FIG.
t ₀ , t ₁ , t ₂ ... v′ ₀ , v′ ₁ sampled every tn,
v′ ₂ ……converts the voltage of v′n into a digital quantity. The second difference detection circuit 17 detects the difference in digital quantity between the current output voltage of the second AD conversion circuit 16 and the output voltage at a predetermined time before the current time, for example, the output at time _t1 . This is to detect a digital quantity corresponding to the differential voltage v' ₀₁ between v' ₁ and the output voltage v' ₀ at time t ₀ . The second DA conversion circuit 18 converts the digital output of the second difference detection circuit 17 into an analog AC output, and obtains an output as shown in FIG. 418. Second low frequency band filter 1
0 removes harmonic components of the analog output from the second DA conversion circuit 18 to obtain the sine wave AC output shown in FIG. 419. Gain adjustment circuit 20
adjusts the output of the second low frequency band filter 19 so that it has the same amplitude as the amplitude of the AC input applied to the input terminal 11 shown in FIG. 4, as shown in FIG. 4, 20. It is. in particular,
This is an AC voltage amplification circuit whose gain can be changed using, for example, a variable resistor. The resistance value of the variable resistor is such that when a constant frequency/constant voltage AC voltage waveform that does not include a DC component is input to the input terminal 11, the voltage generated at the DC output terminal 23 is 0.
Set it so that The AC output terminal 21 is the output terminal of the gain adjustment circuit 20, and as shown in FIG. 4, only the constant frequency sine wave vf of the AC input applied to the input terminal 11 appears as an output. The AC component removal circuit 22 is connected to the input terminal 1
A DC voltage Vdc is generated at the DC output terminal 23 by adding the AC input from 1 and the output of the gain adjustment circuit 20.

Next, this operation will be explained. The fourth input terminal 11
When a constant frequency sine wave vf on which a DC component Vdc is superimposed as shown in _{FIG .} , t ₂ ... tn, the sampled voltages v ₀ , v ₁ , v ₂ ... are converted into digital outputs corresponding to vn. The digital outputs corresponding to these voltages v ₀ , v ₁ , v ₂ . . . vn are sequentially sent to the differential detection circuit 1
3, and at time t ₀ voltage 0 and voltage v ₀
The differential voltage between Vao = Vdc, at time t ₁ , v ₁ - v ₀
=V ₀₁ , and v ₂ −v ₁ =V ₁₂ at time t ₂ . Similarly, the difference voltage between the current output voltage and the output voltage at a predetermined time period a predetermined time before the current time is detected in the same manner. These differential voltages (digital signals)
In the first DA conversion circuit 14,
It is converted to alternating current as shown in . This exchange is the first
The high frequency components are removed by the low frequency band filter 15, resulting in a sinusoidal alternating current as shown in FIG. This enlarged view is shown in FIG. 4, 15'.
The second AD conversion circuit 16 converts voltages v' ₀ , v _{' 1} , v' ₂ , . . . v sampled at each time point t ₀ , t ₁ , t ₂ . ′n is converted into a digital output corresponding to n. These voltages v′ ₀ , v′ ₁ ,
v′ ₂ ……Digital output corresponding to v′n is 2 in order
is applied to the difference detection circuit 17, and at time t ₀ , the difference voltage Vbo between voltage 0 and voltage v' ₀ , at time t ₁ , v' ₁ - v' ₀ = V ₀₁ , and at time t ₂ , v' ₂ ―v′ ₁ =
v′ ₁₂ and thereafter, the difference voltage between the current output voltage and the output voltage at a predetermined time point before the current time is sequentially detected in the same manner. These differential voltages (digital signals) are converted into alternating current in the second DA conversion circuit 18 as shown in FIG. The harmonic components of this alternating current are removed by the second low frequency band filter 19, and the alternating current becomes a sinusoidal alternating current as shown in FIG. 419. This AC is adjusted by the gain adjustment circuit 20 to have the same amplitude as the AC input applied to the input terminal 11, and the AC output terminal 2
1, a sine wave vf shown in FIG. 420 is obtained. This sine wave vf is obtained by removing the DC voltage Vdc from the AC input shown in FIG. 4 and 11 applied to the input terminal 11, and has a phase shift of 180 degrees. Therefore, the AC component removal circuit 22 adds the AC input shown in FIG. 4 11 applied to the input terminal 11 and the output of the gain adjustment circuit 20 shown in FIG. 23, the DC component Vdc shown in FIG. 421 can be obtained.

In the embodiment shown in FIG. 3, the time from time _t0 to time _t2 , that is, the first AD conversion circuit 1
The period during which 2 samples 2 times is 20 gain adjustment times.
The output is not stable. Therefore, the DC component Vdc is obtained from the output of the output terminal 23 after the two sampling periods, but the two sampling periods are sufficiently short and negligible compared to the conventional one cycle. It is something. Therefore, as shown in Figure 2b, the DC component Vdc ₁ becomes the DC component
Even if the voltage changes to Vdc ₂ , the DC component Vdc ₂ can be detected immediately after the voltage changes and stabilizes.

As described above, according to the present invention, a DC component superimposed on a constant frequency sine wave can be detected in a short time.
Furthermore, the control time when superimposing a constant level DC component on a constant frequency sine wave can be shortened. Furthermore, it has various effects such as being able to measure and control the modulation degree of a constant frequency AM modulated wave in a short time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional AC/DC separation and detection device. FIG. 2 is an explanatory diagram of the operation of FIG. 1. FIG. 3 is a block diagram showing one embodiment of the AC/DC separation and detection device according to the present invention. FIG. 4 is an explanatory diagram of the operation of FIG. 3. In the figure, 11 is the input terminal, 12 is the first
AD conversion circuit, 13 is a first difference detection circuit, 14
is the first DA conversion circuit, 15 is the first low frequency band filter, 16 is the second AD conversion circuit, 17
is a second difference detection circuit, 18 is a second DA conversion circuit, 19 is a second low frequency band filter, 20
21 is a gain adjustment circuit, 21 is an AC output terminal, 22 is an AC component removal circuit, and 23 is a DC output terminal.

Claims (1)

[Scope of Claims] 1. A first AD conversion circuit that samples an AC input on which a DC component is superimposed and converts it into a digital quantity every minute time, and a current output of the first AD conversion circuit and a current output of the first AD conversion circuit. a first difference detection circuit that detects the difference between each digital quantity and the output at a point before a predetermined time; a first DA conversion circuit that converts the output of the first difference detection circuit into an analog quantity; a first low frequency band filter that removes harmonic components from the output of the DA conversion circuit; and a second AD conversion circuit that samples the output of the first low frequency band filter every minute time and converts it into a digital quantity. , a second difference detection circuit that detects the difference in each digital amount between the current output of the second AD conversion circuit and the output at a predetermined time before the current time; a second DA conversion circuit that converts the output into a quantity, a second low frequency band filter that removes harmonic components of the output of the second DA conversion circuit, and a variable gain AC amplifier circuit; a gain adjustment circuit that adjusts the gain of the output of the bandpass filter so that it has the same amplitude level as the AC input; and an AC component removal circuit that uses the output of the gain adjustment circuit and the AC input as inputs to detect the DC component. An AC/DC separation and detection device characterized by: