JP2693537B2 - Phase difference detection method and synchronization detection method for sinusoidal alternating current amount - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to various devices such as a generator and an electric device such as a load controller, in which it is necessary to insert the opening / closing contacts in synchronization with both sides of the opening / closing contacts. In the above, the present invention relates to a method of measuring a phase angle of two arbitrary sine wave AC amounts and detecting a phase difference from these phase angles, and a method of detecting a time when the phase difference becomes zero.

(Prior art) Conventionally, when a generator is operated in parallel by opening and closing contacts, or when two or more grids are connected by opening and closing contacts by using a load controller provided at an opening and closing point of a power transmission / distribution system. In some cases, the following phase angle detection method and phase angle control method are adopted. That is, the phase angle of each sine wave alternating current amount (voltage in this case) is measured on both sides of the switching contact, and then the phase difference between both voltages is detected from these measurement results. Turn on the switching contact.

If the opening / closing contacts are turned on in a state where the phase angles of the two sine wave alternating current amounts do not match, various inconveniences such as overvoltage occurring in the system and damage to electric equipment occur.

For this reason, it is necessary to accurately detect the phase difference between the two sine wave alternating current amounts when the opening / closing contacts are closed.

The conventional phase angle detection method will be described below with reference to FIGS. 6 and 7.

FIG. 6 is an explanatory diagram of the case where the phase angles of the voltages on both sides of the switching contact 1 are measured and the generator (G) 2 is operated in parallel. Here, it is assumed that an ideal case where a DC bias does not occur in both voltages is considered.

First, the phase angles of both sides of the switching contact 1 (in FIG. 6, the generator 2 side is the A side and the non-generator side is the B side) are measured. These phase angle measurements are usually performed by measuring each electrical angle (or time) (so-called zero cross point) when the sine wave voltage on both sides of A and B reaches the reference potential (zero potential). .

For example, in FIG. 7, (a) shows a comparison between the waveforms of the A-side voltage v _A and the B-side voltage v _B that is out of phase with respect to v _A. Here, the peak values V _A and V _B of the respective voltages v _A and v _B and the angular frequencies ω _A and ω _B are equal, and their values are V and V, respectively.
If ω is and the phase difference between the two voltages is α, then v _A , v
_B is represented by v _A = Vcosωt v _B = Vcos (ωt + α). By the way, the phase difference α is generally obtained by finding the zero-cross points of the voltages v _A and v _B as described above and converting the time difference between the zero-cross points into the phase difference. Side zero crossing points t _A1 , t _A2 ,…, t _B1 ,
Measure t _B2 , ... respectively. And FIG. 7 (b),
As shown in (c), the sine wave voltages v _A and v _B are converted to square waves v _As and v _Bs in the positive and negative regions (in FIGS. 7B and 7C, the dotted line indicates the negative region). Shows a square wave).

Next, as shown in FIG. 7 (d), FIG.
The exclusive OR (XOR) of the square waves v _As and v _{Bs in} (c) is obtained. Here, since an ideal case where the centers of the amplitudes of v _A and v _B coincide with the reference potential is considered, the time difference between t _An and t _Bn t _αn = t _Bn −t _An (n: 1, 2, ...) Is constant regardless of n. When the t _.alpha.n at this time is t _alpha, the phase difference between the A-side and B-side alpha is, _α = ω × t α becomes (rad.).

Further, when the phase control of the generator 2 is performed so that the phase angles of both the A and B sides of the switching contact 1 are matched, the zero cross points t _A1 , t _A2 , ..., T _B1 , t _B2 , While measuring each of ..., For example, an operation such as adjusting the input of the generator 2 is performed to change the phase angle on the A side. Then, when the phase angles on both sides of A and B match, the switching contact 1 is closed.

The phase angle detection method and the phase angle control method applied to the load controller are the same in principle as the phase angle detection method and the phase angle control method described for the generator 2 and will not be described in detail. In Case of,
For example, the reactive power is supplied to one of the A and B sides to match the phase angles of the A and B sides, and then the switching contacts are closed.

(Problems to be Solved by the Invention) However, in the above-described conventional phase angle detection method and phase angle control method, since the reference zero potential is different on both sides of the switching contact 1, the measured values of v _A and v _B A DC bias is often applied to. Further, a DC bias (for example, when the electric potential at the neutral point of the generator is not zero) possessed by the system itself may be added to each voltage waveform on both sides of A and B of the switching contact 1.

Such a DC bias is caused by various causes, for example, secular change of system characteristics, environmental change (for example, temperature change), etc., and actually occurs frequently.

FIG. 8 (a) shows voltage waveforms v _A , v _B when the zero potentials of the voltages on both sides of A and B of the switching contact 1 shown in FIG. 6 are different (v in FIG. 8). _B is shown as having a DC bias Δv _B ). Here, waveforms of the square waves v _As and v _Bs when the phase angles on both sides of A and B are measured by the conventional phase angle detection method are shown in FIGS. 8 (b) and 8 (c).

By the way, as shown in each of FIGS. 8 (a) to 8 (c),
Although the amplitude center of v _A coincides with the reference potential (that is, the center of the amplitude is on the time axis (t)), v _B is deviated from the time axis (t) in the amplitude direction by the DC bias Δv _B. There is. Therefore, the ratio of the time occupied in the positive region side of the rectangular wave to the time occupied in the negative region side differs for v _As and v _Bs . As a result, as shown in FIG. 8 (d), for example, even when v _A and v _B have the same angular frequency, t _B1 −t _A1 ≠ t _B2 −t
_{As in A2} , there is a disadvantage in that the measurement timing is shifted by a time corresponding to the phase difference α, and accurate phase angle detection (particularly detection of a point where the phase angle is zero) becomes impossible.

Further, under such a circumstance, when the opening / closing contact 1 is closed, the generators are operated in parallel in a state where the phase angles on both sides of the opening / closing contact 1 do not match (in the case of phase control by the load controller, Since the power system will be connected in the same state), overcurrent has occurred in the system, causing inconveniences such as damage to each device connected to the system and occurrence of knocking of system voltage and current. .

Furthermore, when controlling the phase angles of the sine wave voltages v _A and v _{B having} different frequencies, as shown in FIG. 8 (d), t _B1 −t _A1 ≠ t _B2 −t _A2 ≠ t _B3 − t _A3 ≠ ...

In addition to this, conventionally, if two sine wave alternating current amounts (for example, v _A and v _B described above) are alternately exchanged by alternating current and direct current by one A / converter, a constant time difference Δt is inevitable.
There is no choice but to capture both sine wave AC amounts (depending on the calculation speed of the A / D converter). Therefore, since it is not possible to simultaneously measure the phase angles of two sine wave AC amounts by one A / D converter, it is not possible to accurately measure the phase difference. Also, in order to enable the above-mentioned simultaneous conversion, it is possible to prepare A / D converters on both sides of the switching contacts to detect both sine wave AC amounts. Since the installation points are different, the reference potential of each A / D converter will be different. Therefore, even if the generation of the DC bias can be prevented to some extent by using, for example, a high-performance instrument transformer or A / D converter, the measurement accuracy of each sine wave becomes different. There are inconveniences such as different minutes for each sine wave and higher cost.

The present invention has been made to solve the above problems, and accurately obtains the phase angles of both sine wave alternating current amounts even when a direct current bias exists in the two sine wave alternating current amounts to be detected. It is an object of the present invention to provide a phase difference detecting method and a synchronization detecting method for detecting the phase difference thereof and detecting the time when the phase difference becomes zero.

(Means for Solving the Problem) The inventors have found that the phase angle of the sine wave AC amount is expressed as a function of the amplitude and the instantaneous value, so that the waveform on one side of the switching contact and the polarity reversal waveform on the other side are By directly measuring the instantaneous values of both waveforms at the intersection of, and using this instantaneous value, the phase difference between the sine waves on both sides of the switching contact can be accurately detected regardless of the presence or absence of DC bias in both sine waves. I got the knowledge.

In order to achieve the above object, the phase difference detecting method according to claim 1 is a phase difference detecting method of two sine wave alternating current amounts, wherein a first sine wave alternating current amount serving as a reference and a second sine wave opposite to each other. The relative DC bias component of the second sine wave AC amount is obtained from the average value of the instantaneous values of the second sine wave AC amount at two consecutive intersections with the inversion wave with respect to the zero potential which is the reference of the wave AC amount, The difference between the instantaneous value of the second sine wave AC amount at the intersection and the relative DC bias component, and continuous 2
The respective displacement amounts of the second sine wave alternating current amount as the difference between the instantaneous value of the second sine wave alternating current amount at the midpoint of the intersection point and the relative direct current bias amount are respectively obtained, and the sum of squares of these displacement amounts is calculated. The amplitude of the second sine wave alternating current amount is obtained from the square root, and the instantaneous value of the second sine wave alternating current amount at the intersection and the displacement amount as the difference between the relative direct current bias and the amplitude of the second sine wave alternating current amount By taking the inverse sine relationship of the ratio with the, the phase angle of the second sine wave alternating current amount with respect to the intersection point is obtained, and the instantaneous value of the first sine wave alternating current amount at the intersection point is between two consecutive intersection points. The instantaneous value of the first sine wave AC amount at the midpoint is obtained, and the amplitude of the first sine wave AC amount is obtained from the square root of the sum of the squares of these two instantaneous values. Of the ratio of the instantaneous value of the wave AC quantity to the amplitude of the first sine wave AC quantity By taking a sine function, the phase angle of the first sine wave alternating current amount with respect to the intersection point is obtained, and the difference between the phase angles of the first and second sine wave alternating current amount with respect to the intersection point is calculated to obtain the first and second It is characterized by detecting the phase difference of the sine wave AC amount.

Further, in the synchronization detecting method according to claim 2, the time when the phase difference between the first and second sine wave alternating current amounts obtained by the phase difference detecting method becomes zero is the first sine wave alternating current amount, 2 is calculated based on the fact that the periodic function created by the intersection of the sine wave alternating current amount with the inversion wave with respect to the zero potential is a function of the difference in angular frequency between the first and second sine wave alternating current amounts. .

(Operation) In the phase detection method according to claim 1, for example, the first sine wave AC amount that serves as a reference on the generator side, such as the system power supply voltage, and the second sine wave on the non-generator side that faces the first AC amount. From the average value of the instantaneous values of the second sine wave alternating current amount at two consecutive intersections with the inversion wave with respect to the zero potential, which is the reference of the alternating current amount,
The relative DC bias component of the sine wave AC amount of is calculated. Here, with respect to the first sine wave AC amount serving as the reference, it does not matter whether or not there is an absolute bias.

Then, the difference between the instantaneous value of the second sine wave alternating current amount at the intersection and the relative direct current two biases, and the instantaneous value of the second sine wave alternating current amount at the midpoint between two consecutive intersections and Each displacement amount of the second sine wave AC amount as a difference between the relative DC bias components is obtained.

The amplitude of the second sine wave alternating current amount is obtained from the square root of the sum of the squares of these displacement amounts, and the displacement as the difference between the instantaneous value of the second sine wave alternating current amount at the intersection and the relative direct current bias amount. By taking the inverse sine function of the ratio between the amount and the amplitude of the second sine wave alternating current amount, the phase angle of the second sine wave alternating current amount at the intersection is obtained.

In addition, an instantaneous value of the first sine wave alternating current amount at the intersection and an instantaneous value of the first sine wave alternating current amount at a midpoint between two consecutive intersections are respectively obtained, and a sum of squares of these two instantaneous values is obtained. The amplitude of the first sine wave AC amount is calculated from the square root of

Then, by taking an inverse sine function of the ratio of the instantaneous value of the first sine wave alternating current amount at the intersection and the amplitude of the first sine wave alternating current amount, the phase angle of the first sine wave alternating current amount with respect to the intersection point is obtained. Ask for.

After that, the phase difference between the two sine wave AC amounts can be detected by obtaining the difference between the phase angles of the first and second sine wave AC amounts.

Therefore, by using this phase difference as a parameter and controlling the phase angle of the second sinusoidal wave AC amount by using an appropriate means, the phase angle of the first and second sinusoidal wave AC amounts can be matched. it can.

In the phase difference detecting method according to claim 2, the time when the phase difference between both sine wave alternating current amounts detected by the method according to claim 1 becomes zero is determined by the periodic function created by the intersection point. This is obtained based on the fact that it becomes a function of the frequency difference. Specifically, the time when the phase difference becomes zero is detected by analyzing the waveform of the periodic function (approximate sine wave). As a result, it becomes possible to find the optimum timing for closing the switching contacts for the parallel operation of the generators.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

(1) Regarding the phase difference detection method according to claim 1, first, the instrument transformers 3a and 3b provided on the generator side (A side) and the non-generator side (B side) of the switching contact 1 shown in FIG. The voltage v _A and v _B on each side of _A and _B are
Take in the converter. Figure 1 (a) shows v _A and
FIG. 3 is a waveform diagram showing v _B , where v _A is a reference first sine wave AC amount, and v _B is a second sine wave AC amount opposite v _A. Here, the DC bias components of v _A and v _B are Δv _A and v
When Δv _B , v _A and v _B are v _A = V _A cos ω _A t + Δv _A v _B = V _B cos (ω _B t + α) + Δv _B. In Figure 1 (a), Δv _A is is shown as zero, an absolute DC bias component Delta] v _B becomes relative DC bias component of its large itself relative to the Delta] v _A.

Further, ω _A and ω _B are the respective angular frequencies of v _A and v _B , and V _A and V _B are the respective peak values (the same value V in FIG. 1 (a)), α (FIG. 1 (a)). Is negative) is the unknown phase difference of both voltages.

Note that v _A and v _B must be sampled at least v _A = −v _B
Point (v _A and v _B polarity inversion waveform with respect to zero potential −v _B
Intersection) t _1, t _2, and ..., t _k, ... and the temporal midpoint t ₁ of said each intersection _{', t 2', ...,} t k ', ... performed in. Regarding the timing of such sampling, at the intersection of v _A and −v _B , for example, both waveforms may be input to an analog comparator and constantly compared, and the time when the output of the comparator is inverted may be detected. Further, a plurality of times corresponding to the intersections of both waveforms may be stored retroactively, and the time corresponding to the next midpoint may be obtained from the average value of the times corresponding to 1/2 of the time between the intersections. Such a method can be easily realized without any particular problems, since the power supply frequency accuracy is generally extremely high and a CPU having an operating frequency significantly higher than the power supply frequency is usually used. Therefore, in general, Δv _B is the peak value V _B
Assuming that sufficiently small as compared with, v _A, v measurements for _B are both voltages v _A, v rows for each value of [pi / 2 before and after an electrical angle value and said each intersection at each intersection of _B Will be seen.

In addition, in FIG. 1 (a), t ₁ and t ₁ ′, t ₂ and t ₂ ′,
,, t _k and t _k ′,…, each time interval is T ₁ , T ₂ ,…, T _k ,…, and t ₁ ′ and t ₂ , t ₂ ′ and t ₃ ,…, t _k ′ are The time intervals with t _{k + 1} , ... Are _denoted as T ₁ ′, T ₂ ′,…, T _k ′,.

Next, v _A and v _B are replaced with pulses that rise at the above t ₁ , t ₂ , ..., T _k (FIG. 1 (b)). At the rising point of this pulse, v _A and v _B (or −v _B ) are separately A / D converted and the instantaneous values of v _A and v _B are measured.

Waveforms at this time are shown in FIGS. 2 (a) and 2 (b). The figure (a) shows the waveform when the phase difference α is not zero, and the figure (b) shows the waveform when the phase difference α is zero.

By the way, since v _A and v _B are v _A = Vcos ω _A tv _B = Vcos (ω _B t + α) + Δv _B , each measured value is Becomes

Here, in the example of FIG. 2A, since t ₁ and t ₂ are separated by π [rad.], Δv _B can be calculated from the above equations of v _B1 and v _B2 . It can be.

Here 'each sampling value at v _An' tn in FIG. _{1, v Bn '(n: 1,2} , ..., k, ...) When, v _A, v peak value v _A of _B, v _B ( These are equal and V) is V _A = (v _An ² + v _An ′ ² ) ^1/2 V _B = {(v _Bn −Δv _B ) ² + (v _Bn ′ −Δv _B ) ² } ^{1 /} It is represented by ² .

By the way, as shown in Fig. 3 (a), the zero point of v _A
V _B of when canceling the P _A, v dc bias component Delta] v _B of _B
Of the zero point and P _B, v _A, the intersection of the -v _B When P _C, v _A, v _B
The phase difference alpha becomes the difference between the distances alpha _B of the electrical angle of the point P _C and the point P _B, the distance alpha _A of the electrical angle between the point P _C and the point P _A. Also, V _A and v _B
The value after removing the DC bias component at t _n is V _An , v _Bn
Since −Δv _B , the phase difference α and the above α _A and α _B are Can be represented by Where v _An and v _Bn , v _An ′ and
Since v _Bn ′ is the same value measured at the same times t _n and t _n ′, v _An = −v _Bn .

By calculating α based on the above equations, the phase difference α between v _An and v _Bn can be detected. In FIG. 3A, α _A > 0, α _B <0, α <0 (α is a delay phase). Further, in this case, by calculating and detecting only α _B and considering the state of change of α, the phase difference α between v _An and v _Bn
Since it is possible to detect a change in the above, only α _B may be measured. The detection of α, α _A , and α _B can be accurately detected by one A / D converter at the same time. Further, in the embodiment of FIG. 3 (a), Δv _A
= 0. However, in the present invention, in order to obtain the phase difference between the first sine wave alternating current amount (v _A ) and the second sine wave alternating current amount (v _B ), the first sine wave alternating current amount (v _A ) is calculated. Since the focus is on the relative DC bias component (Δv _B ) of the second sine wave AC amount (v _B ) as a reference, the DC bias component Δv _{A of} the first sine wave AC amount (v _A ) It is applicable with or without.

Similarly in FIG. 3 (a), but using the polarity inversion waveform of v _B with respect to the reference potential as -v _B, than the reference potential with polarity inverted waveform of v _B for potential higher DC bias component Delta] v _B But the same can be said. FIG. 3 (b) shows an example in which a polarity reversal waveform of v _B is used for a potential higher by this DC bias Δv _B. Compared with FIG. 3 (a), the position of point P _C is Although changing, the positions of the points P _A and P _B are the same, so the phase difference α is the same as in the case of FIG. 3 (a).

Further, even when the DC bias components Δv _A and Δv _B are zero, the expression (1) holds as it is. FIG. 4 (a),
FIG. 6B is a waveform 4 diagram showing respective waveforms when the phase difference α is zero and when the phase difference α is not zero when Δv _A and Δv _B are zero.

By the way, even when the angular frequencies ω _A and ω _{B of} v _A and v _B are the same, the above equation holds. In this case, the angular frequency ω
_The detection accuracy is higher than that when _A and ω _B are different. The operation at this time is similar to that in the case where ω _A and ω _B are different, and the description thereof will be omitted.

The following effects are particularly remarkable in the case of Δv _A = Δv _B = 0, including the case where the angular frequencies are different and the case where they are equal. That is, when the amplitudes of both v _A and v _B are different,
It is assumed that it is detected that the phase difference α = 0 when the bias is not generated. At this time, v _Ak = v _Bk = 0 (k is an arbitrary integer).

At this time, | v _Ak ′ | = const., And this value indicates the maximum value (peak value) of v _A. This also means
The same applies to v _B , which is | v _Bk ′ | = const., and this value indicates the maximum value (peak value) of v _B.

Therefore, it can also be detected that the peak values V _A and V _B of both voltages are equal at the time of | v _An ′ | = | v _Bn ′ | (n: 1,2,3, ...).

(2) Regarding the synchronization detection method according to claim 2, since the phase angle and phase difference of v _A and v _B can be accurately detected by the detected values of the phase difference α and the electrical angles α _A and α _B based on , For example, the angular frequency ω _{A of the} generator 2 shown in FIG.
And the angular frequency ω _{B of the} system differ from each other by Δω, by means such as adjusting the input or excitation of the generator 2
Both phase angles of v _A and v _B can be matched. Also, use a load controller etc. to adjust the reactive load,
Both phase angles of v _A and v _B can be matched.

The locus of the intersection of the two voltages v _A and −v _B at this time is shown in FIG. Further, FIG. 11B is a diagram in which the time axis of the locus of the intersections in FIG.

As can be seen from these figures, the locus does not become a straight line, and the magnitude of the angular frequency becomes two sine waves v _C1 , v _C2 with Δω = | (ω _A −ω _B ) / 2 | sine wave
v _C1 and v _C2 are functions of Δω.

At this time, the reciprocal f _C of the period between the intersection points t _Cn of v _A and −v _B is Becomes

Further, the potential difference V _C1 ^pp , V _C2 ^pp from one peak voltage value of v _C1 and v _{C2 to} the other peak voltage value is V _C1 ^pp = v _An-1 ′ + v _An ′ V _C2 ^pp = v _{Bn- 1} '+ v _Bn '.

Therefore, v _C1, v peak value v _C1, v _C2 of _C2 is Becomes

If the phase difference α between v _A and v _B is calculated by the formula, and the waveforms of v _C1 and v _C2 are analyzed by, the time when the phase difference between both waveforms becomes zero (corresponding to the intersection of both waveforms) Time) can be calculated. For example, by utilizing the fact that the waveform at the intersection becomes a sine wave, the instantaneous value of one waveform (for example, v _C1 ) at constant time intervals when the phase difference between the two waveforms was zero last time (v at time t1 ₁ , t ₂ v ₂ , ..., t ₆ v ₆ , ...)
Is stored together with the elapsed time.

Here, if the phase difference was zero at time t ₆ last time (v ₆ = 0), if the current instantaneous value v _x of v _C1 is between v ₂ and v ₃ , then the phase difference is The time until zero is between (t ₆ −t ₂ ) and (t ₆ −t ₃ ) is approximately {(t ₆ −t ₂ ) + (t ₆ −t ₃ )}. It can be said to be / 2.

As a result, the opening / closing contact 1 can be closed at an appropriate timing. Further, by the above analysis, in addition to each phase difference α,
Angular frequency ω _A , ω _B , sine wave voltage v _A , v _B effective value Etc. can be calculated in the same way, and based on this calculation result
It is possible to control v _A and v _B.

In each of the above embodiments, the voltage phase difference detection method and the synchronization detection method have been described, but the present invention can be applied to the detection of the phase difference of other sine wave AC amounts such as the current and the synchronization detection. By adopting this method, it is not necessary to perform A / D conversion all the time, and it is also possible to derive and control the phase angles, voltages, and frequencies of v _An and v _{Bn based on} the results of calculations performed at various points. Becomes

(Effect of the invention) In the phase difference detection method according to claim 1, without performing the phase angle detection at the so-called zero-cross point, the polarities of one of the sine wave alternating current amounts are reversed, and the two sine wave alternating current amounts are directly compared. Therefore, even if there is a DC bias component in the measured values of both waveforms, it is possible to detect the phase difference with high accuracy by canceling the DC bias component, and the system current caused by the overcurrent generated in the system can be detected. It is possible to prevent damage to each device, system voltage, current knocking, pulsating current, and the like. Further, since the phase angles of both sine waves are obtained by directly and simultaneously comparing the two sine wave AC amounts, the phase difference can be detected by one A / D converter. .

Further, when the phase difference between the two sine wave alternating current amounts becomes zero, it becomes possible to accurately detect the peak value of each sine wave alternating current amount.

Further, in the synchronization detecting method according to the second aspect of the present invention, since the focus is on the periodic function formed by the locus of the intersection points of the two sine wave alternating current amounts, based on the detection result of the phase difference described above, the phase difference becomes zero. It became possible to detect the time point accurately.

[Brief description of the drawings]

FIG. 1 (a) is a waveform diagram showing a voltage waveform for explaining the phase difference detecting method according to claim 1, FIG. 1 (b) is a waveform diagram showing a pulse waveform, FIG. 2 (a), ( FIG. 3B is a waveform diagram showing a sine wave voltage and the like when a DC bias is generated, FIGS. 3A and 3B are enlarged waveform diagrams showing the vicinity of the reference voltage, and FIG. (B) is a waveform diagram showing a sine wave voltage and the like when no DC bias is generated for explaining the embodiment of the phase difference detecting method according to claim 1, and FIGS. 5 (a) and 5 (b) are claims. Waveform diagram for explaining an embodiment of the synchronization detection method described in Item 2, FIG. 6 is a circuit diagram for explaining the present invention and the prior art, and FIGS. 7 (a) to 7 (d) are explanations for the prior art. FIGS. 8A to 8D are waveform diagrams for explaining the problems of the conventional technique. 1 …… Switching contact 2 …… Generator 3a, 3b …… Transformer for instrument v _A , v _B …… Sine wave AC amount V _A , V _B , V …… Peak value ω _A , ω _B …… Angular frequency v _An , v _Bn …… Measured value Δv _A , Δv _B …… DC bias α …… v _A , v _B phase difference

Claims (2)

(57) [Claims] 1. A method for detecting a phase difference between two sine wave alternating current amounts, wherein a first sine wave alternating current amount serving as a reference and an inversion wave with respect to a zero potential serving as a reference of a second opposing sine wave alternating current amount. The relative DC bias component of the second sine wave alternating current amount is obtained from the average value of the instantaneous values of the second sine wave alternating current amount at two consecutive intersection points, and the instantaneous value of the second sine wave alternating current amount at the intersection point and the above The difference from the relative DC bias component, and the respective displacements of the second sine wave AC component as the difference between the instantaneous value of the second sine wave AC component at the midpoint of two consecutive intersections and the relative DC bias component. Then, the amplitude of the second sine wave AC amount is calculated from the square root of the sum of the squares of these displacement amounts, and the difference between the instantaneous value of the second sine wave AC amount at the intersection and the relative DC bias component is calculated. Of the displacement amount as a ratio of the amplitude of the second sine wave AC amount By taking the inverse sine relationship of the second sine wave alternating current amount with respect to the intersection point, and at the midpoint between two consecutive intersection points with the instantaneous value of the first sine wave alternating current amount at the intersection point. An instantaneous value of the first sine wave alternating current amount is obtained, and an amplitude of the first sine wave alternating current amount is obtained from a square root of a sum of squares of these two instantaneous values. By taking the inverse sine function of the ratio between the instantaneous value of and the amplitude of the first sine wave alternating current amount, the phase angle of the first sine wave alternating current amount with respect to the intersection is obtained, and the first and second sine wave alternating current A phase difference detection method for detecting the amount of alternating sine wave alternating current, wherein the phase difference between the first and second amounts of alternating sine wave alternating current is detected by calculating the difference in the phase angle with respect to the intersection of the amounts. 2. The time when the phase difference between the first and second sine wave alternating current amounts obtained by the phase difference detecting method according to claim 1 becomes zero, the first sine wave alternating current amount and the second sine wave alternating current amount. A sine wave alternating current characterized in that it is calculated based on the fact that the periodic function created by the intersection of the wave alternating current amount with the inversion wave with respect to the zero potential is a function of the difference between the angular frequencies of the first and second sine wave alternating current amounts. How to detect quantity synchronization.