JPS61142958A - Phase detecting apparatus - Google Patents

Abstract

PURPOSE:To carry out stable detection, by a method wherein the first and the second phase detecting circuits are provided, and wherein the output is compared and the output for signal for switching signal is generated, and wherein the input to the second phase detecting circuit is switched. CONSTITUTION:A phase detecting apparatus is organized with the first and the second phase detecting circuits 100, 200, a signal selecting circuit 50, a disagreement detecting circuit 60, a voltage detecting circuit 70, and a switching signal generating detecting circuit 80. To the first phase detecting circuit 100, detected signal input is provided, and to the second phase detecting circuit 200, the detected signal input or the corresponding signal from the first phase detecting circuit 100 is provided by being selected through the signal selecting circuit 50. The output of the first and the second phase detecting circuits 100, 200 is compared through the disagreement detecting circuit 60, and by the output or the output of the voltage detecting circuit 70, the signal switching circuit 50 is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a phase detection device used for phase control of power conversion devices such as DC power transmission and frequency conversion.

[Technical background of the invention and its problems] Fig. 3 shows a three-phase thyristor bridge, in which three-phase AC voltages R, S, and T are input, and a thyristor U is input.

By controlling the firing phase of V, W, X, Y, and Z,
It controls the DC voltage generated between DC terminals P and N, and is used as a power conversion device for DC power transmission, frequency conversion, etc.

When controlling the phase of this three-phase silica bridge, it is necessary to digitally accurately detect the phase of the three-phase AC voltage.
Phase detection devices using an ock loop (hereinafter also referred to as a PLL) are often used.

FIG. 4 f'i is a block diagram showing the configuration of a conventional phase detection device disclosed in Japanese Patent Application Laid-Open No. 55-34851, in which the oscillation frequency mainly changes depending on the input voltage.

A variable frequency oscillator 1, a counter 2 that counts the output Hals of the variable frequency oscillator 1, a digital count signal θ of the counter 2, and a three-phase AC voltage R1S, T are input,
It consists of a phase comparator 3 that applies an analog phase difference signal Δθ to a variable frequency oscillator l, and a low-pass filter 4 that removes harmonic components of this phase comparator 3.

In this case, the 1st phase comparator 3 receives 3-phase AC voltages R, S.

A three-phase/two-phase converter 31 converts T into two-phase AC voltages vld and vlq synchronized with this, and two-phase converters corresponding to two-phase AC voltages Mi11 and vl, respectively, based on the digital count signal θ of the counter 2. ROM32 and digital/analog converter (
(hereinafter referred to as D/A converter) 33a, 33b, and 2
A phase difference signal Δθ is obtained by calculating the phase difference between the phase AC voltages vld, vlq and the corresponding two-phase AC voltages vFd, vFq.
The arithmetic circuit that outputs the .

Note that sine wave data with a phase shift of 90 degrees Fi is written in the ROM 32.

In FIG. 4, a three-phase/two-phase converter 31 inputs three-phase AC voltages R, S, and T, and generates a two-phase AC voltage Vl expressed by the following equation.
d, vlq are output. However, ■l: amplitude θl: phase.

On the other hand, based on the digital count signal θ of the counter 2, the two-phase AC voltage shown in the following equation, that is, the analog phase detection signal F (11 PQ or D/A converter 33a,
33b, respectively.

However, θ11=detection phase.

Further, the arithmetic circuit 34#'i calculates the following equation to obtain the two-phase AC voltages vld, vlq and the analog phase detection signal vFd.

0 that outputs a phase difference signal Δθ (θl−02) with Vy.
This phase difference signal Δθ is applied to the variable frequency oscillator 1 via the low-pass filter 4, and a feedback loop is configured such that the 1 phase difference signal Δθ becomes zero. A companion digital phase detection signal θ is output from the counter in synchronization with the voltages R, 8, and T.
This is used for phase control of the three-phase thyristor bridge shown in FIG.

Note that the phase detection response speed, that is, the phase detection response speed, is mainly determined by the time constant of the low-pass filter 4, and a low-pass filter with an appropriate time constant is selected depending on the use of the power conversion device.

Although such conventional phase detection devices have very high performance and greatly contribute to the digitalization of phase control devices, they have the following drawbacks when used in power conversion devices such as DC power transmission.

■ When the AC voltage is established close to the rated voltage, the response of the phase detection determined by the low-pass filter is slowed down in order to perform stable phase detection without being affected by minute fluctuations in the amplitude of the AC voltage. If a fault occurs in the AC system and the phase of the AC voltage suddenly changes, not only will it be impossible to follow this, but the fault in the AC system will not be removed, and even if the AC voltage is established near the rated voltage, it will immediately become appropriate. phase detection cannot be performed.

■ Also, conversely, the response of the phase detection determined by the low-pass filter should be made faster in order to quickly perform appropriate phase detection at the time of an AC system failure or when the AC system failure is removed. Therefore, it is difficult to perform stable phase detection when the AC voltage is established to be close to the rated voltage.

[Purpose of the Invention] The present invention has been made in order to eliminate the drawbacks of the above-mentioned conventional products, and can be used appropriately even when the voltage of each phase of the AC voltage falls below a predetermined value due to an AC system failure, such as a ground fault. It is possible to detect the AC voltage phase, and even if the AC voltage is once lost and then restored, it is not only possible to immediately detect the appropriate phase. It is an object of the present invention to provide a phase detection circuit that can stably detect the phase of a fundamental wave without being affected by minute disturbances in voltage.

[Summary of the Invention] To achieve this object, the phase detection device of the present invention includes a phase-locked loop circuit in which a low-pass filter is inserted before a variable frequency oscillator, and detects a two-phase AC voltage or a signal to be detected. A first circuit that outputs an AC voltage corresponding to the detected signal by applying, as the detected signal, a two-phase AC voltage obtained by converting the multiphase AC voltage to the phase-locked loop circuit.

A phase-locked loop circuit in which a low-pass filter with a wider pass frequency band and a smaller time constant than the low-pass filter of the first circuit is inserted in the front stage of the variable frequency oscillator, and a two-phase AC voltage or input as an input signal is included. A second circuit that outputs a digital phase detection signal of an input signal by applying a two-phase AC voltage obtained by converting a multiphase AC voltage as a signal to this phase-locked loop circuit, a detected signal, and an output AC of the first circuit. a signal selection circuit that selects one of the voltages by a signal switching signal and inputs the selected signal to the second circuit; an output signal of the low-pass filter of the first circuit; and an output signal of the low-pass filter of the second circuit; When the output signal of the low-pass filter of the first circuit does not match the output signal of the low-pass filter of the second circuit within a predetermined range, a mismatch detection circuit outputs a mismatch signal and a signal to be detected is detected. A voltage detection circuit that detects that each phase of a two-phase AC voltage or a multiphase AC voltage as a detected signal is below a predetermined value and outputs a voltage drop signal, and a mismatch signal that is output from the mismatch detection circuit. and a switching signal generation circuit which outputs a signal switching signal used in the signal selection circuit based on the voltage drop signal from the voltage detection circuit, and converts the two-phase AC voltage as the detected signal to the multi-phase AC voltage as the detected signal. Each phase of the phase AC signal is not less than a predetermined value,
And if the output signal of the low-pass filter of the first circuit and the output signal of the low-pass filter of the second circuit match within a predetermined range, the input signal of the first circuit is used as the input signal of the second circuit. Using the output AC pressure of If the signal and the output signal of the low-pass filter of the second circuit do not match within a predetermined range, the detected signal is used as the input signal of the second circuit. .

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the configuration of a phase detection device according to the present invention, and the same reference numerals as in FIG. 4 indicate the same elements.
Input the three-phase AC voltages R9S and T as detected signals, and generate the three-phase AC voltage ell+ corresponding to the detected signals.
a first phase detection circuit 100 that outputs es+eT;
A second phase detection circuit 200 which inputs the three-phase current voltage R, 8, T or the corresponding three-phase current voltage eR+e5+eT and outputs a digital phase detection signal θ200, and this second phase The detection circuit 200 receives three-phase AC voltages R, 8, and T, and a signal selection circuit 50 that selects which of the two corresponding three-phase AC voltages to be applied using the signal switching signal C (G) and the first The angular velocity signal ω1 output from the low-pass filter 41 of the phase detection circuit 100 and the angular velocity signal ω2 output from the low-pass filter 42 of the second phase detection circuit 200.
a discrepancy detection circuit that compares the angular velocity signals ω1 and angular velocity signals ω2 and outputs a discrepancy signal NBQU if they do not match within a predetermined range; and a voltage detection circuit 70 that detects that the voltage has reached a predetermined value and outputs a voltage drop signal UV.

a switching signal generation circuit 80 that outputs a signal switching signal CHG to the signal switching circuit 50 when the voltage drop detection signal UV is output from the voltage drop detection circuit 70 or when the mismatch signal NEQU is output from the mismatch detection circuit 60; It consists of

Among these, the elements of the phase detection circuit 100 shown in FIG. 2 include ROMs lla to llc and a D/A converter 128.
~12C, and the $2 phase detection circuit 200 #iC has exactly the same configuration as in FIG. and the low-pass filter 42 constituting the second phase detection circuit 200 have different time constants, and the former has IQQ (
A time constant with a large time constant is used so that the phase detection response speed is on the order of −1 (see) msec). A relatively small one is used.

Further, when the signal selection circuit 50 outputs the signal switching signal CHG from the switching signal generation circuit 80, the three-phase AC voltage R, which is the signal to be detected, is input as an input signal to the second phase detection circuit 200. 8. Select T, signal switching signal CH
When G is not output, the first phase detection circuit 100
The 3-phase AC voltage signals eH, eB, and eT output by the controller are selected.

The operation of the phase detection device configured as described above will be explained below.

First, when the three-phase AC tortoise pressures R, 8, and T supplied to the three-phase thyristor bridge shown in FIG. ■Do not output.

Further, at this time, assuming that the signal selection circuit 50 selects the three-phase AC voltage signals eH, eB, and eT output from the first phase detection circuit 100 as the input signals of the second phase detection circuit 200, The angular frequency signal ω1 output from the low-pass filter 41 of the first phase detection circuit 100 and the angular frequency signal ωzn output from the low-pass filter 42 of the second phase detection circuit 200 are equal, and the mismatch detection circuit 60 detects a mismatch. Does not output signal NEQU.

In this state, a failure occurs in the AC system, and the three-phase AC voltage R,
8. When T drops below a predetermined value for the rated voltage, the voltage detection circuit 70 detects the voltage drop and outputs the voltage drop detection signal U.
v to the switching signal generation circuit 80, and the switching signal generation circuit 80 outputs the signal switching signal CHG to the selection circuit 50.

The selection circuit 50 receives the signal switching signal CHG and selects the three-phase AC voltage signal eR, 83 which has been output from the first phase detection circuit as an input signal to the second phase detection circuit 200.
, eT was selected, and the signal to be detected was changed to 3.
Select phase AC voltages R, 8, and T. As a result, the digital phase detection signal θZ output from the second phase detection circuit
OO rapidly follows sudden phase changes in three-phase AC voltages R, S, and T as signals to be detected due to an AC system failure, and detects an appropriate phase. Furthermore, when the AC system fault is removed and the three-phase AC voltage R9S, T becomes equal to or higher than the predetermined value for the rated voltage.

The voltage detection circuit 70"W stops outputting the voltage drop detection No. 4tg UV. At this time, the first phase detection circuit 10
At 0, the response of the low-pass filter 41 is slow, so that the output three-phase AC voltage eB+ e3+ eT that follows the phases of the three-phase AC voltages R, 8, and T as detected signals cannot be obtained. The reason why the three-phase AC voltage +eB+ 67 that follows the phases of the three-phase AC voltage 1 voltage R, S, and T cannot be obtained is because the angular frequency signal ωl output from the low-pass filter 41 of the first phase detection circuit 100 This is when the angular frequency signals ω2 output from the low-pass filter 42 of the second phase detection circuit 200 become equal.Until this state is reached, the mismatch detection circuit 60 continues to output the match signal NEQU and input the mismatch signal NBQU. The switching signal generation circuit 80 continues to generate the signal switching signal CHG, and the signal selection circuit 50 continues to generate the signal switching signal CHG.
As the input signal 00, the three-phase AC voltages R, 8, and T as the signals to be detected continue to be selected. The signal selection circuit 50
The reason why the three-phase sound voltage el+65+eT from the first phase detection circuit 100 is selected as the input signal of the phase detection circuit 200 is that the three-phase AC voltages R, 8, and T are equal to or higher than a predetermined value for the rated voltage, and First phase detection circuit 100
The angular frequency signal ωl from the low-pass filter 41 of the second phase detection circuit 200 becomes equal to the angular frequency signal ω3 from the low-pass filter 42 of the second phase detection circuit 200, and the voltage drop signal UV and the mismatch signal N
This is the point in time when the signal switching signal CHG from the switching signal generation circuit 80 disappears due to the disappearance of EQU.

In this way, even if the three-phase AC voltages R, 8, and T input to the power converter fill become temporarily unbalanced due to a line accident or the like and a sudden change in phase occurs, the second phase detection circuit 200 Not only can the phase synchronized with the 3-phase current voltage R, 8°T be detected, but also the phase can be detected immediately when the rated voltage rises from a state where the 3-phase AC voltage has been lost. When the voltages R, 8, and T are above a predetermined value for the rated voltage, the first phase detection circuit 100 follows the fundamental wave of the three-phase AC voltage R, 8, and T, and detects disturbances other than the fundamental wave. Three-phase AC voltage e that does not respond to
ll+ eB+ eTV is obtained, and this is used as the output signal of the second phase detection circuit 200 as a digital phase detection signal θ20.
In order to obtain 0, stable phase detection can be performed against minute disturbances in the AC system, and thus the power converter f1 can be operated stably.

FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same elements. Phase detection circuit 1
The first phase detection circuit 110 is constructed by removing the ROMs 10a-10C and the D/A converters 118-IIc from the phase detection circuit 200 of FIG.
The second phase detection circuit 210 was constructed by removing the two-phase converter 31 (FIG. 3).

and selecting either the output of the three-phase/two-phase converter of the first phase detection circuit 110 and the D/A converter 33a or 33b as the input signal of the second phase detection circuit 210,
In addition, the first advantage is to use a two-pole, double-throw signal selection circuit 50a instead of a three-pole, double-throw signal selection circuit 50.
It is different from the illustration.

In FIG. 2, when three-phase AC voltages R, 8, and T are applied to the first phase detection circuit 110, the arithmetic circuit 34 described above
For this three-phase AC cage pressure R, 8, T, there is a two-phase AC voltage without time delay ■lli! ■IQ and a two-phase AC voltage delayed by about 100100 (~1 [S]) ■Fd + vFq are added by the action of the low-pass filter 41. In this embodiment, three-phase AC voltages R, S, Instead of selecting either T and the corresponding three-phase AC voltage e1166+67, select one of the two-phase AC voltage 1d, vlq and the two-phase AC voltage vF(1+v, . second
It is added to the arithmetic circuit 34 of the phase detection circuit 210.

As a result, the counter 2 of the second phase detection circuit 210 can quickly detect the phase when the voltage (%3-phase AC voltage)<, S, T temporarily drops and rises from zero voltage.

The fifth embodiment shown in FIG. 2 is superior to the embodiment shown in FIG. 1 in that the configuration is simplified.

In each of the above embodiments, the phase detection device was described for a power converter fIt that inputs three-phase current voltage to obtain DC power. By removing 31, it is also possible to detect the phase of a two-phase AC voltage, and as a special case, for a device that converts a multi-phase AC voltage other than three-phase AC into DC, the second
Phase detection similar to that described above is possible by using a polyphase/two-phase converter instead of the three-phase/two-phase converter 31 shown in the figure.

[Effects of the Invention] As is clear from the above explanation, the phase detection device of the present invention can operate properly even when the voltage of each phase of the AC voltage falls below a predetermined value with respect to the rated voltage due to a failure in the AC system. Not only can the phase of the AC voltage be detected, and even if the AC voltage temporarily disappears and then recovers, it is possible to immediately detect the appropriate phase. .

C has the effect of being able to stably detect the phase of AC voltage without being affected by minute disturbances in AC voltage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of one embodiment of a phase detection device according to the present invention, FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. 3 is a general power converter device. FIG. 4 is a block diagram showing the configuration of a conventional phase detection device suitable for phase control of this power conversion device. 1...Variable frequency oscillator 2...Counter 3...
・Phase comparator 4.41.42...Low pass filter 11
a ~ 11C, 32・ROM 12a ~ 12C, 33a, 33b...Digital, analog converter 50.50m...Signal selection circuit 60...Discrepancy detection circuit 70...Voltage detection circuit 8
0...Switching signal generation circuit 100, 110...First phase detection circuit 200,
210...Second phase detection circuit U+V+W+X+Y+
Z-v vsp Agent Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A phase detection device used for phase control of a power conversion device includes a phase-locked loop circuit in which a low-pass filter is inserted before a variable frequency oscillator, and detects a two-phase AC voltage or a detected signal as a detected signal. a first circuit that outputs an AC voltage corresponding to the detected signal by applying a two-phase AC voltage obtained by converting a multiphase AC voltage as a detection signal to the phase-locked loop circuit; and a stage before the variable frequency oscillator; A phase-locked loop circuit including a low-pass filter with a wider pass frequency band and a smaller time constant than the low-pass filter of the first circuit, and a two-phase AC voltage as an input signal or a multi-phase AC voltage as an input signal. a second circuit that outputs a digital phase detection signal of the input signal by applying a converted two-phase AC voltage to the phase-locked loop circuit, and a second circuit that outputs a digital phase detection signal of the input signal; Compare the output signal of the low-pass filter of the first circuit with the signal selection circuit selected by the switching signal and input to the second circuit, and compare the output signal of the low-pass filter of the second circuit. When the output signal of the low-pass filter of the circuit does not match the output signal of the low-pass filter of the second circuit within a predetermined range, the mismatch detection circuit outputs the mismatch signal and the two-phase AC voltage or the detected signal is detected. A voltage detection circuit that detects that each phase of a polyphase AC voltage as a detection signal is below a predetermined value and outputs a voltage drop signal; a mismatch signal output from the mismatch detection circuit; and a mismatch signal output from the voltage detection circuit. A switching signal generation circuit that outputs a signal switching signal used in the signal selection circuit changes each phase of the two-phase AC voltage as the detected signal or the multiphase AC signal as the detected signal to a predetermined value. Not less than
And if the output signal of the low-pass filter of the first circuit and the output signal of the low-pass filter of the second circuit match within a predetermined range, the input signal of the first circuit is used as the input signal of the second circuit. Using the output AC voltage, each phase of the two-phase AC voltage as the signal to be detected or the multi-phase AC signal as the signal to be detected is equal to or less than a predetermined value, or the output signal of the low-pass filter of the second circuit and the 1. A phase detection device characterized in that, when the output signals of the low-pass filters of the two circuits do not match within a predetermined range, the detected signal is used as the input signal of the second circuit.