JPS607408B2 - filter circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter circuit that eliminates harmonic number components and extracts fundamental wave components.

FIG. 1 is a diagram for explaining the 180o phase discrimination method.

In the figure, V,,V2 are basic vectors. Assume now that vector V2 is in phase delayed by 90o with respect to vector V. Further, vector V3 is assumed to be a calculated vector. FIG. 1A shows the case where the vector V3 is in the first quadrant. In this case, the vector V is in the range from oo to 180o with the vector V, as a reference, and the vector V is positive. When the vector V, changes from positive to negative, the vector V3 becomes a positive value. On the other hand, when the vector V3 changes from positive to negative, the vectors V, , V2 both become negative values, and the positive values stop here. In Figure 1, vector V3 is vector V. The case is shown in which the phase is advanced by 900 relative to the phase. In this case, when the vector V changes from positive to negative, the vector V3 becomes positive. On the other hand, vector V3
When V changes from positive to negative, vector V2 becomes positive, and vectors V, , V3 never stop at positive values. That is, in this case, there is a limit. Next, FIG. 1C shows a case where the vector V3 is in the second quadrant. In this case, the positive waveform cannot be stopped. Thinking in the same way, Figure 1, Figure 2 is the limit, and Figure 1 is the limit.
The positive waveform stops in Figures E and B. Therefore, the positive waveform is continuous only when the vector V3 is in the second quadrant. By configuring a circuit in which this positive waveform operates continuously, it is possible to create a relay such as a distance relay. As an example, a distance relay utilizes the principle of FIG. 1 to construct a vector as shown in FIG. 2.

Here, V,, V2, and V'3 are basic vectors, and V3 is a vector obtained by calculating V3=V'3-knV4.
Now, when vector knV4=k,V4, vector V3
indicates the direction of the third quadrant, so there is a break in the positive waveform, resulting in no operation. Also, vector knV4=
When k2V4, the limit is reached, and when vector knV4=k3V4, vector V3 indicates the direction of the second quadrant, so the positive waveform is continuous and operation is activated. Vector kn for the same aircraft
As the phase angle of V4 is changed, the operating range becomes within the shaded area. This indicates that when vectors V, , V2, and V'3 are given, the operating limit is at a point parallel to vector V and parallel to vector V2, with vector V3 as the apex. Next, consider the case where the third harmonic component is superimposed on the vector V in FIG.

FIG. 3A shows the case where only the fundamental wave component is used as the vector V. Figure 3 is a diagram in which the waveform of vector V is converted into a rectangular wave. FIG. 3C shows the waveform of a vector V' in which the fundamental wave component and its third harmonic component are superimposed in a 900-lead state. When such a vector V' is converted into a rectangular wave, it becomes as shown in Figure 3 2, and the phase is 8 compared to the figure 3.
You can get something more advanced. Therefore, the operating force at this time is due to the vector V', which is obtained by advancing the vector V by a phase of 8, as shown in FIG. As described above, this type of relay has the disadvantage that its operating range widens when harmonic components are superimposed on the input.

This invention has been made in view of this point. FIG. 5 is a circuit diagram showing one embodiment of the present invention, which is applied when the input impedance of the circuit connected to the output side is large.

FIG. 6 is a vector diagram illustrating the operation of the circuit diagram shown in FIG. 5. In FIG. 5, 11 is a transformer, which has coils 1, 2 and 3 as primary to tertiary coils, and the winding starts of coils 2 and 3 are indicated by x marks. A capacitor C. is connected in series between terminals a and b of the coil 2.
and resistance R. , and a capacitor C2 and a resistor R2 connected in series are connected in parallel. Capacitor C and resistor R
, and the connection point d between the capacitor C2 and the resistor R2.
Resistors R4 and 3 are connected in series between. Output V from between the connection point h of the resistors R3 and R4 and the terminal g of the coil 3.
get ut. Terminal f of the coil 3 and terminal e of the intermediate tap of the coil 2 are connected. Next, the operation will be explained with reference to FIG.

Here, a current with an angular velocity including the third harmonic component flows through the coil 1, the voltage between the terminals e and b of the coil 2 is Veb, the voltage between the terminal e and the connection point c is V, and the terminal e, Let the voltage between the connection point d be V, and let the fundamental wave current flowing through the capacitor C, the connection point c and the resistor R be 1,c,
The current of the third harmonic component flowing together with the current 1,c is 1
Let 1 and d be the fundamental wave current flowing through the resistor R2, the connection point d, and the capacitor C2, and let 1 be the current of the third harmonic component flowing together with the currents 1 and d. Here, when the input of the third harmonic component is applied, the voltages Veb and Ve
The values of resistors R, , R2, and capacitors C and C2 are determined so that c and V have a phase difference of 1200, and the value of resistor R3 is made equal to the value of resistor b. With this setting, the following equation holds true in the phase shift circuit including the capacitor C and the resistor R.

R213d=1:Z3...--[2] Therefore, the potential of the connection point h for the input of the third harmonic component is Vec /2 and Ve
From the sum of d and 2, a vector m is obtained in the middle of the vector af. If a vector voltage is applied to the coil 3 to cancel this vector fh, the output will be V. The third harmonic component of ut is canceled. Next, using these component constants to find the voltage across capacitor C for the input of the fundamental wave component, we get:
The voltage X is expressed by equation '3'. R, 1, C; Ki 1・
C: 1:

Therefore, the position of the connection point C when the third harmonic component is applied becomes C' when the fundamental wave component is applied, and ta is relative to the vector ab.
By proceeding n-13zo3≠79o, it moves to the intersection point C' on the circumference shown in FIG. Similarly, capacitor C2 and resistor R2
In the phase shift circuit according to, the following equation holds true.

Here, ``x is the voltage across the resistor R2; 1・d
:R21・d=1:X skin [4} By substituting this in the Liu formula, we get X= direction.

Therefore, the position of the connection point d when the third harmonic is applied becomes d' when the fundamental wave component is applied, and the leg - rock =
After a delay of 300 minutes, we moved to Figure 6's Dim Sum.

As a result, the potential of the connection point h with respect to the input of the fundamental wave component shifts from the sum of Vec'/2 and Ved'/2 to the midpoint h' of the line segment, so the output V skin is '10fg:
V.

It becomes ut. In this way, even if the harmonic component is superimposed on the fundamental wave component, only the fundamental wave component can be derived on the output V side.

FIG. 7 is a circuit diagram showing another embodiment of the present invention, which is applied when the input impedance of the circuit connected to the output side is small.

FIG. 8 is a vector diagram illustrating the operation of the circuit shown in FIG. 7. In FIGS. 7 and 8, the same reference numerals as in FIGS. 5 and 6 indicate the same parts. Regarding FIGS. 7 and 8, only the parts different from FIGS. 5 and 6 will be explained.

In Fig. 7, resistors R6 and R5 are connected between connection points c and d.
are connected in series. A terminal g of the coil 3 is connected to a connection point 1 between resistors R5 and R6 via a resistor R7. Output V.
ut is the voltage between the connection point 1 and the terminal f of the coil 3. The operation will be explained with reference to FIG.

In the phase shift circuit of the resistor R and capacitor C, the component constants satisfy the following equation at the third harmonic input. R.・Target: Hiroshi;
&=1:ノ3...■ 1 -- Therefore, the ear left phrase=3ノ3...■.

As a result, the voltage Vkc between kc has a phase lead of 1200 relative to the input. Next, in the phase shift circuit including the resistor R2 and the capacitor C3, the component constants are such that the following equation holds true at the third harmonic input. Mama Poison/Phantom: R213d=1:ノ3-…”{7}
1 --Therefore, for horses, 5=ノ3...■.

As a result, the voltage Ved between ed has a phase lead of 2400 relative to the input. If the values of resistors R5, R6, and R7 are made equal, the voltage ysasa between fg is in phase with the input, so the current supplied to the output side via resistors R5, R6, and R7 is Vout=Vkc+Ved+Vfg, which is zero. Therefore, the third harmonic component can be removed. Next, Figures 5 and 6 show the case where the fundamental wave component input is applied.
Proceeding with the study in the same way as in the figure, we get R, I, and so on.

：Shi1・C=1:X・…・From the side '6- and ■ formula, x=3 no 3 get.

Therefore, n-13-3≠79o, and the voltage at the connection point C advances by 790 from the vector ab, moving to the intersection 〇. Similarly, the following equation holds true in the circuit of resistor O2 and capacitor C2.

Left 1・d: R21・d! 1:X・Skin OQ From '7} and Taneshiki ・ X = Hermitage Twist.

Therefore, the voltages at the desk-Iwasu and starvation points shift from the vector ab to the intersection point d'', which is delayed by 300 points.

Therefore, the output when the fundamental wave component is input is Vout=
A current corresponding to Ved'+Vfg+Vkc' can be derived.

In the above embodiment, the case where the third harmonic component is removed from the fundamental wave has been explained, but by providing an appropriate number of phase shift circuits and combining their outputs as in the above embodiment, the desired harmonic component can be removed. Can be removed.

Further, in the above embodiment, the phase shift circuit is constructed from a resistor and a capacitive reactance, but it is obvious that it may be constructed from a resistor and an inductive reactance.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the 180o phase discrimination system, Figure 2 is a characteristic diagram of a distance relay, Figure 3 is a waveform diagram of the operation of a conventional distance relay, and Figure 4 is a characteristic diagram of a conventional distance relay 0 device. Figure, 6th
Figure 6 is a circuit diagram showing one embodiment of this invention, Figure 6 is a vector diagram explaining the operation of Figure 5, Figure 7 is a circuit diagram showing another embodiment of this invention, Figure 8 is Figure 7. FIG. 2 is a vector diagram explaining the operation of FIG. 5 1...Transformer, C,, C2...Capacitor, R
,~R6...Resistance. In addition, in the figures, the same reference numerals indicate the same parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1 In a filter circuit that removes the n-times harmonic component of an input signal in which an n-times harmonic component is superimposed on the fundamental wave component, V_1=V∠0°, V for the n-times harmonic component.
_2=V∠(2π)/n, V_3=V∠(4π)/n,
…, Vn=V∠(2(n-1)π)/n voltage V_1,
A filter circuit comprising n phase shifters for obtaining V_2...Vn and a circuit for synthesizing the respective voltages.