JPH1090311A - AC amplitude detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a circuit constitution by forming an a.c. amplitude estimation value, controlling a controller to make zero an error between the value and an amplitude value of an a.c. signal to be detected, and obtaining the amplitude value from an output. SOLUTION: A phase advancement circuit 5, receiving a voltage signal from an a.c. voltage detector 4, outputs a shift phase voltage signal having a phase advanced by a predetermined amount. A multiplier 14 and a multiplier 15 operate respectively a first, a second a.c. estimation signals by multiplying a first a.c. reference wave of the same phase as that of a voltage signal output from a trigonometric function calculator 13, a second phase-advanced a.c. reference wave output from the calculator 13 by an output of a controller 11. An output of a subtracter 6 becomes a difference of the voltage signal and the first a.c. estimation signal, and an output of a subtracter 7 becomes a difference of the output of the phase advancement circuit 5 and the second a.c. estimation signal. These outputs are multiplied by the first, second a.c. reference waves, and the results are added thereby obtaining an output at an adder 10. The output of the controller 11 as an integrator is changed so that the output of the adder 10 becomes close to zero, whereby the output is nearly equal to the voltage signal, and an amplitude value of a target voltage is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an amplitude of an AC signal (AC voltage or AC current) used for control or protection of a device connected to a power system, for example, a circuit breaker, a power converter, a power conditioner, and the like. The present invention relates to an alternating-current amplitude detection device that performs

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a conventional AC amplitude detecting device disclosed in Japanese Patent Application Laid-Open No. 7-225249. In the drawing, reference numeral 1 denotes a detected system, 2 denotes an amplitude V, and an angular frequency ω _0. A single-phase AC power supply, 3 a load connected to the single-phase AC power supply 2, and 4 an AC voltage detector for detecting an AC voltage of the system to be detected and outputting a voltage signal (AC signal) v proportional to the AC voltage. Detector (AC signal detecting means), 100 is a differentiating circuit for differentiating the voltage signal v and outputting a voltage signal v2, 101 is an output of the AC voltage detector 4 and the differentiating circuit 100 to a calculation result of the trigonometric function calculator 108. The output of the AC voltage detector 4 and the differentiation circuit 100 is converted into a voltage signal v
Multiply-accumulator for converting cosine wave components and sine wave components of
2 is a multiplication circuit for multiplying the voltage signal v by a cosine wave component, 10
4 is a multiplication circuit for multiplying the voltage signal v by a sine wave component, 10
3 is a multiplication circuit for multiplying the voltage signal v2 by a cosine wave component,
05 is a multiplication circuit for multiplying the voltage signal v2 by a sine wave component,
106 is a subtractor for subtracting the output of the multiplier 105 from the output of the multiplier 102, and 107 is an adder for adding the output of the multiplier 103 and the output of the multiplier 104 and inverting the sign of the addition result. Reference numeral 108 denotes a trigonometric function calculator for calculating the cosine and sine of the reference phase θ ₀ of the voltage signal v.

An amplitude / phase difference detector 109 detects the amplitude V of the voltage signal v by converting the cosine wave component a and the sine wave component b of the voltage signal v output from the product-sum calculator 101 into polar coordinates. Means. 110 indicates that the voltage signal a is 2
A multiplier for squaring the voltage signal b;
112 is an adder for adding the multiplication results of the multipliers 110 and 111, 113 is a square root operation circuit for calculating the square root of the addition result of the adder 112, and 114 is a division for dividing the voltage signal a by the operation result of the square root operation circuit 113 115, an inverse cosine operation circuit for calculating the inverse cosine (in the range of 0 to 180 degrees) of the output of the divider 114, 116 outputs "1" when the voltage signal b is positive, and "1" when the voltage signal b is negative. A sign operation circuit 117 that outputs -1 ″ is a multiplier that multiplies the output of the inverse cosine operation circuit 115 by the output of the sign operation circuit 116 and calculates the phase θ of the voltage signal v in the range of −180 to 180 degrees. is there. In this example, an AC voltage is detected as an AC signal.
An alternating current may be detected as an alternating signal.

Next, the operation will be described. When the AC voltage detector 4 detects the voltage signal v, the differentiating circuit 100 differentiates the voltage signal v and outputs a voltage signal v2 which is 90 degrees out of phase with the voltage signal v. That is, the voltage signal v =
If V cos θ, a voltage signal v2 = −V sin θ is output. On the other hand, trigonometric function calculator 108 receives the reference phase theta ₀ of the voltage signal v, and calculates the cosine cos [theta] ₀ and sine sin [theta ₀ of the reference phase theta _0. The reference phase θ ₀ is the detected system 1
Is the phase of the frequency equal to the frequency of.

[0005] The product-sum calculator 101 compares the voltage signal v and the voltage signal v2 with the cosine cos θ ₀ and the sine of the reference phase θ _0.
The rotation coordinate conversion is performed based on sin θ ₀ , and the voltage signal v and the voltage signal v 2 are converted into a cosine wave component a and a sine wave component b of the voltage signal v. The rotational coordinate transformation of the product-sum calculator 101 is expressed by the following equation. _{a = Vcosθcosθ 0 + Vsinθsinθ 0 =} Vcos (θ-θ 0) ··· (1) b = Vsinθcosθ 0 -Vcosθsinθ 0 = Vsin (θ-θ 0) ··· (2)

The amplitude / phase difference detecting means 109 performs polar coordinate conversion on the voltage signal a and the voltage signal b converted by the product-sum calculator 101, and detects the amplitude V and the phase difference (θ-θ ₀ ). The details are shown below.

First, the voltage signals a and b are respectively applied to the multiplier 1
After being squared by 10, 111, they are added by an adder 112. After that, the square root is calculated by the square root calculation circuit 113. That is, the output of the square root operation circuit 113 = (V ² cos ² (θ−θ ₀ ) + V ² sin ² (θ−θ ₀ )) ^1/2 = (V ² (cos ² (θ−θ ₀ ) + sin ² ( θ−θ ₀ ))) ^1/2 = (V ² ) ^1/2 = V (3) and outputs the amplitude V of the AC signal.

The voltage signal a is divided by the output of the square root operation circuit 113 by the divider 114, and the inverse cosine operation circuit 115 calculates the inverse cosine of the output of the divider 114 as shown below. Output of inverse cosine operation circuit 115 = cos ⁻¹ (Vcos (θ−θ ₀ ) / V) = (θ−θ ₀ ) (4) where 0 <θ <180 degrees. Since the voltage signal b has a negative value when (θ−θ ₀ ) is negative, if the output of the sign operation circuit 116 is multiplied by the output of the sign operation circuit 116 by the output of the inverse cosine operation circuit 115, −180 to 180 The phase difference (θ-θ ₀ ) can be detected in the range of degrees.

[0009]

Since the conventional AC amplitude detecting device is constructed as described above, the amplitude V and the phase θ of the AC voltage can be detected at high speed without a delay element in the calculation part. However, there is a problem that complicated arithmetic processing such as square root arithmetic is required, and a circuit configuration becomes complicated, and when this method is realized by software, an arithmetic time and a memory are required. Further, the detection error also becomes an integrated value of errors of the respective circuit elements, which may be disadvantageous in accuracy. Further, in applications such as operating a circuit breaker due to a voltage drop,
It is sufficient if only the amplitude component can be detected, and in many applications, phase detection is unnecessary.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an AC amplitude detecting apparatus which can simplify a circuit configuration, reduce errors and improve detection accuracy. Aim. It is another object of the present invention to improve the detection speed and reduce the influence of the error accompanying the phase detection on the amplitude detection.

[0011]

According to a first aspect of the present invention, there is provided an AC amplitude detecting apparatus for detecting an AC signal of a system to be detected, and a phase synchronized with the AC signal detected by the AC signal detecting means. Phase detection means for outputting a signal; AC reference wave generation means for generating an AC reference wave based on the phase signal; and multiplication for generating an AC estimation signal by multiplying the amplitude reference value of the AC signal by the AC reference wave. Means, subtraction means for outputting an AC error signal by taking the difference between the AC signal and the AC estimation signal, DC conversion means for converting the AC error signal into a DC error signal whose polarity is not inverted, and the DC error signal And an amplitude estimation value control means for controlling the amplitude estimation value of the AC signal based on

Further, in the AC amplitude detecting apparatus according to the present invention, the DC converting means comprises a multiplying circuit for multiplying and outputting an AC error signal with an AC reference wave.

According to a third aspect of the present invention, in the first aspect, the DC converting means includes a division circuit for dividing the AC error signal by the AC reference wave and outputting the result.

According to a fourth aspect of the present invention, there is provided an AC amplitude detecting device for detecting an AC signal of a system to be detected.
Phase detection means for outputting a phase signal synchronized with the AC signal detected by the AC signal detection means, and outputting a phase-shifted AC signal obtained by shifting the phase of the AC signal detected by the AC signal detection means by a predetermined value A first AC reference wave generating circuit for generating a first AC reference wave based on the phase signal; and a first AC reference wave by multiplying the amplitude estimation value of the AC signal by the first AC reference wave. A first multiplication circuit that generates one AC estimation signal, a first subtraction circuit that outputs a first AC error signal by calculating a difference between the AC signal and the first AC estimation signal, A second AC reference wave generating circuit for generating a second AC reference wave obtained by shifting the phase of the AC reference wave by the predetermined value, and multiplying the amplitude estimation value of the AC signal by the second AC reference wave The second AC A second multiplication circuit for generating a signal; a second subtraction circuit for outputting a second AC error signal by taking a difference between the phase-shifted AC signal and the second AC estimation signal; A multiplying and adding circuit for adding an error signal multiplied by the first AC reference wave and a second AC error signal multiplied by the second AC reference value to output an error signal; An amplitude estimation value control circuit for controlling the amplitude estimation value of the AC signal based on the error signal is provided.

According to a fifth aspect of the present invention, in the AC amplitude detecting apparatus according to the fourth aspect, the second AC reference wave generating circuit generates a second AC reference wave based on a phase signal from the phase detecting means. It is something to do.

According to a sixth aspect of the present invention, in the alternating-current amplitude detecting apparatus according to the fourth or fifth aspect, the phase shift amount in the phase shift circuit is set to a value of 90 degrees or a value close to 90 degrees.

According to a seventh aspect of the present invention, in the AC amplitude detecting apparatus according to the sixth aspect, the phase shift circuit comprises a differential operation circuit.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an AC amplitude detecting apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 5 denotes a phase advance circuit as a phase shift circuit for advancing the voltage signal v by a predetermined phase, and 6 denotes a first AC signal obtained by subtracting an output of a later-described multiplier circuit 14 from an output of the AC voltage detector 4. A subtractor 7 serving as a first subtraction circuit for outputting an error signal is used as a second subtraction circuit for subtracting an output of a later-described multiplication circuit 15 from an output of the phase lead circuit 5 and outputting a second AC error signal. , A multiplier for multiplying the output of the subtractor 6 by a first AC reference wave, which is an output of a trigonometric function calculator 13 described later, and 9, a multiplier for multiplying the output of the subtractor 7 by the triangular function calculator 13. A multiplier for multiplying the output of the second AC reference wave, 10 is an adder for adding the output of the multiplier 8 and the output of the multiplier 9, and 11 is the output if the output of the adder 10 is a positive value. Increase the AC amplitude estimate, and decrease the output if it is negative. That controller as amplitude estimation value control circuit, 12 is a phase detection circuit as a phase detecting means for outputting the voltage signal v, it synchronized with the phase, 1
Reference numeral 3 denotes first and second AC reference wave generation for calculating a first AC reference wave having the same phase as the voltage signal v and a second AC reference wave whose phase has been advanced by the amount of phase advance of the phase advance circuit 5. A trigonometric function calculator as a circuit, 14 is a multiplier as a first multiplier circuit for multiplying the AC amplitude estimation value and the first AC reference wave, and 15 is a multiplier for calculating the AC amplitude estimation value and the second AC reference wave. A multiplier as a second multiplication circuit for multiplication.

Next, the operation will be described. First, an AC voltage detector 4 detects an AC voltage of the system 1 to be detected, and outputs a voltage signal v proportional to the AC voltage, as in the conventional case. Then, when the voltage signal v is input, the phase lead circuit 5 outputs a phase-shifted voltage signal v2 in which the voltage signal v is advanced by a predetermined phase lead amount at the frequency of the voltage signal v. The details are shown below.

FIG. 2 is a block diagram showing a detailed configuration example of the phase advance circuit 5, in which 21 is a phase delay circuit having a time constant T, 22 is a gain multiplication circuit, and 23 is a gain multiplication circuit 2.
This is a subtraction circuit for subtracting the output of the phase delay circuit 21 from the output of the second circuit. The gains K1 and K2 in the phase delay circuit 21 and the gain multiplication circuit 22 are represented by the following equations.

K 1 = cosψ + (1 / ω ₀ T) sinψ (5) K 2 = ((1 + ω ₀ ² T ² ) / ω ₀ T) sinψ (6) where ψ is a predetermined phase advance amount.

The output of the phase advance circuit 5 is obtained by converting the voltage signal v to v =
When Vsinθ is set, the following equation is obtained. The output of the phase leading circuit 5 = Im {(K1 - K2 / (1 + jω 0 T)) Vexp (jθ)} = Im {(cosψ + (1 / ω 0 T) sinψ) Vexp (jθ) - (((( 1 + ω ₀ ² T ² ) / ω ₀ T) sinψ) / (1 + jω ₀ T)) Vexp (jθ)｝ = (cosψ + (1 / ω ₀ T) sinψ) Vsinθ − ((1 / ω ₀ T ) sinψ) Vsinθ + (sinψ) Vcosθ = Vcosψsinθ + Vsinψcosθ = Vsin (θ + ψ) (7) Therefore, the output v2 of the phase lead circuit 5 is a signal that is advanced by a predetermined phase ψ from the input signal. You.

Further, since the phase detection circuit 12 detects the phase of the voltage signal v by a method such as PLL, the trigonometric function calculator 13 can output the first AC reference wave sin θ having an amplitude of 1. Further, since the phase lead amount ψ of the phase lead circuit 5 is also known, the trigonometric function calculator 13 can also output the second AC reference wave sin (θ + ψ) having the amplitude of 1. Assuming that the estimated AC amplitude value output from the controller 11 is Vhat, the first AC estimated signal Vhat · sin θ of the voltage signal v is output by the multiplier 14 and the second AC estimated signal Vhat · sin ( θ + ψ) is calculated.

Therefore, the output of the subtractor 6 is the voltage signal v
(= V sin θ) and the first AC estimation signal Vhat · sin θ, and the output of the subtractor 7 is the output v 2 of the phase lead circuit 5.
(= Vsin (θ + ψ)) and the second AC estimation signal Vhat · sin (θ +
ψ). The first and second outputs are
The output Δv of the adder 10 obtained by multiplying the AC reference waves sin θ and sin (θ + ψ) and adding them is given by the following equation. Δv = (Vsinθ−Vhat · sinθ) sinθ + (Vsin (θ + ψ) −Vhat · sin (θ + ψ)) sin (θ + ψ) = (V−Vhat) (sin ² θ + sin ² (θ + ψ)) ・ ・ ・ (8) Since (sin ² θ + sin ² (θ + ψ)) in Equation 8 is a positive number,
The controller 11 controls the output Δv of the adder 10 to be close to 0.
Is used as an integrator to change the output Vhat, V ≒ Vhat, and the amplitude value of the target AC voltage can be detected.

The controller 11 includes an integrator,
It may be a proportional integrator or a combination thereof with a filter such as a temporary delay element.

As described above, Embodiment 1 of the present invention
Creates an estimated AC amplitude value Vhat, controls the controller 11 so that an error Δv from the amplitude value V of the AC signal v to be detected becomes zero, and obtains the amplitude value V from the output Vhat. Therefore, the conventional square root operation is not required, and the circuit configuration is simplified. Further, even if there is an error in the calculation element, for example, the error added in the form of multiplication to Equation 8 does not affect the detection accuracy, and thus the detection error can be reduced as a whole.

Embodiment 2 FIG. In the first embodiment described above, the phase lead amount ψ is not specified. Therefore, as can be seen from Equation 8, Δv which is the control input of the controller 11 is
Although it is always positive and its polarity does not reverse, its amplitude generally fluctuates with time (θ). Therefore, the controller 11 needs to be provided with an integral element, and the detection speed is reduced accordingly. Embodiment 2
The phase lead amount 設定 is set to 90 degrees so that the detection speed can be improved.

That is, assuming that 度 is 90 degrees in Expression 8, Δv = (V−Vhat) (sin ² θ + cos ² θ) = V−Vhat (9), and Δv does not change with time (θ). Therefore, the controller 11 can control Δv to be zero without providing an integral element, and the detection speed is improved accordingly.

FIG. 3 shows a configuration example of the phase lead circuit 5 for realizing the phase lead amount ψ = 90 degrees, which will be described below in comparison with FIG. That is, in FIG. 3, reference numeral 21a denotes a differential operation circuit, and reference numeral 22 denotes a gain multiplication circuit with a set value of 0, which can be omitted.

If the voltage signal v is set to Vsinθ, the output of the differential operation circuit 21a becomes -Vcosθ, and the subtracter 2
3, the output becomes Vcos θ, and the phase lead amount ψ = 9
0 degree is realized.

Incidentally, the phase detection circuit 12 outputs the voltage signal v
And outputs a phase signal θ ₀ synchronized with it.
When an error is assumed in the phase signal θ ₀ , that is, θ ₀ ≠ θ
, The phase error Δ on the output Δv of the adder 10
The effect of θ = θ−θ ₀ is minimized when the phase lead ψ is set to 90 degrees. Hereinafter, the reason will be described.

That is, when θ ₀ ≠ θ, the output Δv of the adder 10 is obtained by equation (9). Δv = (Vsinθ-Vhat · sinθ 0) sinθ 0 + (Vsin (θ + ψ) -Vhat · sin (θ 0 + ψ)) sin (θ 0 + ψ) = V (sinθsinθ 0 + sin (θ + ψ) sin (θ ₀ + ψ)) −Vhat · (sin ² θ ₀ + sin ² (θ ₀ + ψ)) = V {sin ² θ ₀ + sin ² (θ ₀ + ψ)} cos (θ-θ ₀ ) + V {sinθ ₀ cos θ ₀ + sin (θ ₀ + ψ) cos (θ ₀ + ψ)} sin (θ-θ ₀ ) −Vhat (sin ² θ ₀ + sin ² (θ ₀ + ψ)) (9) here, substituting [psi = 90 degrees, the output _{^{Δv = V {sin 2 θ 0}} + cos 2 θ 0} cos (θ-θ 0) of the adder _{10 + V {sinθ 0 cosθ 0} - cosθ 0 sin θ ₀ } sin (θ−θ ₀ ) −Vhat (sin ² θ ₀ + cos ² θ ₀ ) = Vcos (θ−θ ₀ ) −Vhat (10) where cos (θ−θ ₀₎ ) $ 1
The effect of the phase error (θ-θ ₀ ) can be minimized. Note that, even if the phase lead amount ψ is not exactly 90 degrees, if the value is close to 90 degrees, the amount related to the phase lead amount 、 in Equation 9 is si
Since n (θ ₀ + ψ) ≒ cos θ _{0 and the} like can be considered, substantially the same effect can be obtained.

Embodiment 3 In the first and second embodiments, the phase advance circuit 5 is provided so that the voltage signal v = Vsin θ
By generating a phase-shifted AC signal Vsin (θ + ψ) advanced by only, and also creating a signal (θ ₀ + ψ) advanced by the same ψ for the phase signal θ ₀ , the AC error signal which is an input of the controller 11 is obtained. Is converted into a DC error signal (Δv in Equation 8) whose polarity is not inverted, and tracking control from Vhat to V is enabled. In the third embodiment, however, the conversion means for converting the DC error signal is used. As an even simpler case, an AC amplitude detecting device which has simplified the overall circuit configuration will be introduced.

FIG. 4 shows an example of this, in which an AC error signal (Vsin θ−Vhat · sin θ) which is the output of the subtractor 6 is shown.
Is multiplied by an AC reference wave sin θ to obtain a DC error signal Δv. That, Δv = (Vsinθ-Vhat · sinθ) sinθ = (V-Vhat) sin 2 θ ··· (11) , and the same first and second embodiments, the output of the multiplier 8 0
By using the controller 11 as an integrator and changing the output Vhat so as to approach Vhat, V ≒ Vhat, and the AC voltage amplitude can be detected while simplifying the circuit configuration.

FIG. 5 shows another specific example of the third embodiment. Here, a divider 16 divides an AC error signal (Vsin θ−Vhat · sin θ) output from the subtracter 6 by an AC reference wave sin θ. As the DC error signal Δv. That is, Δv = (Vsin θ−Vhat · sin θ) / sin θ = V−Vhat (12), and the form is the same as the equation 9 in the second embodiment. However, in actual arithmetic processing, it is a divisor
Since the output error may increase in the range where sinθ is 0 or a value close to 0, it is necessary to avoid division in this range, and as a result, there is a disadvantage that the calculation error increases slightly.

In each of the above embodiments, each arithmetic circuit is treated as hardware. However, it is needless to say that the same effect can be obtained even if it is realized by arithmetic processing by a computer. Further, the detected amount is not limited to the AC voltage, but may be another type of alternating signal such as an AC current.

[0037]

As described above, in the alternating-current amplitude detecting device according to the first aspect, the alternating-current signal detecting means for detecting the alternating-current signal of the system to be detected, and the synchronizing signal with the alternating-current signal detected by the alternating-current signal detecting means. Phase detection means for outputting a phase signal obtained by the above-described method, AC reference wave generation means for generating an AC reference wave based on the phase signal, and generating an AC estimation signal by multiplying the amplitude reference value of the AC signal by the AC reference wave. Multiplication means, subtraction means for outputting an AC error signal by taking the difference between the AC signal and the AC estimation signal, DC conversion means for converting the AC error signal into a DC error signal whose polarity is not inverted, and DC With the amplitude estimation value control means for controlling the amplitude estimation value of the AC signal based on the error signal, there is no need for a complicated operation element such as a square root operation,
It is possible to detect the AC amplitude with a simple configuration.

Further, the DC converting means of the AC amplitude detecting device according to the second aspect of the present invention comprises a multiplying circuit which multiplies the AC error signal by the AC reference wave and outputs the multiplied signal. Becomes possible.

Further, since the DC converting means of the AC amplitude detecting device according to the third aspect of the present invention includes a dividing circuit for dividing the AC error signal by the AC reference wave and outputting the divided signal, the response speed of the amplitude estimated value controlling means can be increased. And the detection speed can be increased.

Further, in the AC amplitude detecting device according to the present invention, an AC signal detecting means for detecting an AC signal of a system to be detected, and a phase signal synchronized with the AC signal detected by the AC signal detecting means is output. Phase detecting means, a phase shift circuit for outputting a phase-shifted AC signal obtained by shifting the phase of the AC signal detected by the AC signal detecting means by a predetermined value, and generating a first AC reference wave based on the phase signal A first AC reference wave generation circuit, a first multiplication circuit for generating a first AC estimation signal by multiplying the amplitude estimation value of the AC signal by the first AC reference wave, By taking the difference from the first AC estimation signal, the first
A first subtraction circuit that outputs an AC error signal, a second AC reference wave generation circuit that generates a second AC reference wave obtained by shifting the phase of the first AC reference wave by the predetermined value, A second multiplication circuit for generating a second AC estimation signal by multiplying the signal amplitude estimation value by the second AC reference wave, and calculating a difference between the phase-shifted AC signal and the second AC estimation signal; To output a second AC error signal.
Subtracting a signal obtained by multiplying the first AC error signal by the first AC reference wave and a signal obtained by multiplying the second AC error signal by the second AC reference value to obtain an error signal , And an amplitude estimation value control circuit that controls the amplitude estimation value of the AC signal based on the error signal. The amplitude can be detected.

Further, the second AC reference wave generating circuit of the AC amplitude detecting apparatus according to the fifth aspect generates the second AC reference wave based on the phase signal from the phase detecting means. Only one detecting means is required, and the circuit configuration becomes simpler.

In the AC amplitude detecting apparatus according to the sixth aspect, the phase shift amount in the phase shift circuit is set to a value of 90 degrees or a value close to 90 degrees, so that the response speed of the amplitude estimation value control circuit is increased. As a result, the detection speed can be increased, and the influence of the output error of the phase detection means on the AC amplitude detection accuracy can be minimized.

Further, since the phase shift circuit of the AC amplitude detecting device according to the present invention comprises a differential operation circuit, a 90-degree phase process can be performed with a simple operation element.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an AC amplitude detection device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a phase lead circuit 5 of FIG.

FIG. 3 is a block diagram showing an internal configuration of a phase lead circuit 5 in the AC amplitude detection device according to the second embodiment of the present invention.

FIG. 4 is a block diagram showing an AC amplitude detection device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing an AC amplitude detecting device different from FIG. 4 in Embodiment 3 of the present invention.

FIG. 6 is a block diagram showing a conventional AC amplitude detection device.

[Explanation of symbols]

1 system to be detected, 4 AC voltage detector, 5 phase lead circuit, 6,7 subtractor, 8, 9, 14, 15 multiplier, 1
0 adder, 11 controller, 12 phase detection circuit, 13
Trigonometric function calculator, 16 divider, 21a Differential operation circuit, v AC signal, v2 phase AC signal, θ ₀ phase signal, Δv DC error signal, Vhat amplitude estimation value.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Motoma Yamamoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Masaaki Oshima 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Satoshi Miyazaki 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Company

Claims (7)

[Claims] 1. An AC signal detecting means for detecting an AC signal of a detected system, a phase detecting means for outputting a phase signal synchronized with the AC signal detected by the AC signal detecting means,
AC reference wave generation means for generating an AC reference wave based on the phase signal, multiplication means for generating an AC estimation signal by multiplying the AC reference wave by the amplitude estimation value of the AC signal, the AC signal and the AC Subtraction means for outputting an AC error signal by taking a difference from the estimation signal; DC conversion means for converting the AC error signal into a DC error signal whose polarity is not inverted; and amplitude estimation of the AC signal based on the DC error signal An alternating-current amplitude detection device including an amplitude estimation value control means for controlling a value. 2. The AC amplitude detecting apparatus according to claim 1, wherein said DC converting means comprises a multiplying circuit for multiplying and outputting an AC error signal by an AC reference wave. 3. The AC amplitude detecting device according to claim 1, wherein the DC converting means comprises a dividing circuit for dividing the AC error signal by an AC reference wave and outputting the result. 4. An AC signal detecting means for detecting an AC signal of a system to be detected, a phase detecting means for outputting a phase signal synchronized with the AC signal detected by the AC signal detecting means,
A phase shift circuit for outputting a phase-shifted AC signal obtained by shifting the phase of the AC signal detected by the AC signal detection means by a predetermined value, and a first AC for generating a first AC reference wave based on the phase signal A reference wave generation circuit for multiplying the amplitude estimation value of the AC signal by the first AC reference wave to obtain a first signal;
A first multiplication circuit for generating an AC estimation signal of the first type, a first subtraction circuit for outputting a first AC error signal by calculating a difference between the AC signal and the first AC estimation signal,
In which the phase of the AC reference wave is shifted by the predetermined value.
A second AC reference wave generating circuit for generating an AC reference wave, and a second multiplying circuit for generating a second AC estimated signal by multiplying the amplitude estimation value of the AC signal by the second AC reference wave A second subtraction circuit that outputs a second AC error signal by taking a difference between the phase-shifted AC signal and the second AC estimation signal; and a first AC reference signal for the first AC error signal. A multiplying and adding circuit for adding a product obtained by multiplying a wave and a product obtained by multiplying the second AC error signal by the second AC reference value to output an error signal; and an amplitude of the AC signal based on the error signal. An AC amplitude detection device including an amplitude estimation value control circuit for controlling an estimation value. 5. The AC amplitude detection apparatus according to claim 4, wherein the second AC reference wave generation circuit generates the second AC reference wave based on a phase signal from the phase detection means. apparatus. 6. The phase shift circuit according to claim 4, wherein the phase shift amount is set to 90 degrees or a value close to 90 degrees.
Or the AC amplitude detection device according to 5. 7. The AC amplitude detecting device according to claim 6, wherein the phase shift circuit comprises a differential operation circuit.