JPH0718895B2 - AC power supply voltage fluctuation detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an AC voltage output from an AC power source, such as a commercial power source, for outputting constant voltage / constant frequency AC power. The present invention relates to a voltage fluctuation detecting device for an AC power supply, which detects a power supply trouble such as a power failure or a momentary interruption of the power supply by detecting a voltage fluctuation with respect to the voltage to be originally output.

[Prior Art] Conventionally, as a voltage fluctuation detection device for such an AC power supply,
There is a device that includes a rectifier and a smoothing circuit, detects an AC voltage fluctuation by once converting an AC voltage output from an AC power supply into a DC voltage and then measuring the value of the DC voltage. .

This AC power supply voltage fluctuation detection device causes a phase delay when the input AC voltage passes through the smoothing circuit, causing a power supply trouble and causing a voltage fluctuation in the AC voltage output from the power supply. However, there is a problem that there is a considerable time delay until the voltage fluctuation is actually detected.

As a countermeasure against this, a device for detecting a power failure by generating a waveform (reference wave) other than the voltage waveform of the power supply and observing the deviation between this waveform and the power supply voltage -181677 No. "blackout detection device", Shokai 59-1793
Proposed in No. 83 “Instantaneous interruption detection device”. According to these methods, since the smoothing circuit is not used, a time delay does not occur and a power failure can be detected promptly.

As the condition of the reference wave used in such a method, it is possible to always keep the same phase as the ideal waveform even if the power supply voltage changes.

[Problems to be Solved by the Invention] However, in the voltage fluctuation detection device for the conventional AC power supply, when the input AC voltage causes a cyclic fluctuation, the reference wave causes a phase shift, Even if a power supply trouble occurs and a voltage fluctuation occurs in the AC voltage output from the power supply, there is a problem that there is a considerable time delay until the voltage fluctuation is actually detected. This problem is caused by the following reasons. That is, in the "power failure detection device", the PLL (Phase-Locked-Loop) is used to maintain the synchronization of the reference waveform with the power supply voltage, but it is present in the square wave output from the PLL. This occurs because an integration operation is performed for the purpose of compensating the phase delay of the degree and converting it into a triangular wave as a pre-process for generating the reference wave. In other words, when the periodic fluctuation of the AC voltage occurs, the square wave of the output of the PLL also changes in synchronization with this, but at this time there is a difference in the integrated value of the plus part and the minus part of the square wave, which is positive. Or it occurs as a negative offset.

Further, in the "instantaneous interruption detection device", by sampling and holding the waveform of the power supply voltage several cycles before, or by outputting a waveform for approximately half cycle using the zero-cross point of the power supply voltage as a trigger, However, these waveforms also have a phase shift because the periodic fluctuation is not taken into consideration.

As described above, in the technique shown in the conventional example, the phase shift occurs when the power supply voltage fluctuates, and the detection time delay occurs as in the case where the smoothing circuit is used.

For this reason, for example, in the uninterruptible power supply to which these are applied, the backup operation of the auxiliary power supply is delayed by the time delay, and the power supply is temporarily stopped, which causes the device to be used. May have an adverse effect.

The present invention has been made in view of the above problems. Even if the power supply voltage fluctuates periodically, power failure such as power failure or momentary interruption can be detected without a time delay. It is an object of the present invention to provide a voltage fluctuation detecting device for an AC power supply, which enables the uninterruptible power supply to always supply stable power when used in a device.

Structure of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structures as means for solving the problems. That is, the voltage fluctuation detecting device for an AC power supply according to the present invention is a sine wave AC generating means for generating a sine wave AC voltage corresponding to a waveform of an AC voltage output from a constant voltage + constant frequency AC power supply, and the sine wave. AC power supply voltage fluctuation for detecting fluctuation of AC voltage from the power supply, comprising deviation calculation means for receiving the sine wave AC voltage generated by the AC generation means and the AC voltage from the power supply to calculate the deviation between the two In the detection device, the sine wave AC generating means receives an AC voltage from the power source and has a phase with respect to this.
A first PLL that outputs a square wave delayed by 90 degrees; and a second PLL that receives the square wave from the first PLL and outputs a sine wave whose phase is delayed by 90 degrees with respect to the square wave. The gist is that it comprises an inverter that receives the sine wave from the second PLL and inverts the sign of this voltage.

Here, the sine wave AC voltage generating means is for generating a sine wave AC voltage that is always in the same phase as the AC voltage output from the power supply, and the magnitude (voltage value) of the sine wave AC voltage is Preferably, it is the same as the AC voltage that is normally output from the power supply, but may be of any other magnitude.

[Operation] In the voltage fluctuation detecting device for an AC power supply of the present invention configured as described above, the sine wave AC voltage generating means causes a constant voltage +
Upon receiving an AC voltage output from a constant frequency AC power supply, a sine wave AC voltage having a predetermined amplitude and always having the same phase as the AC voltage output from the power supply is generated.

The generation of this sine wave AC voltage is performed as follows. That is, the first PLL provided in the sine wave AC generating means generates a square wave whose phase is delayed by 90 degrees with respect to the AC voltage from the power supply. Due to the well-known characteristics of the PLL, this square wave maintains a constant waveform even if voltage fluctuations such as momentary interruption occur in the AC voltage from the power supply, and even if periodic fluctuations occur Since the synchronism is maintained, a square wave whose period is also changed is output. In the second PLL that follows, a sine wave that is synchronized with this square wave and whose phase is delayed by 90 degrees is generated. This sine wave is a waveform in which the phase is delayed by 180 degrees while maintaining synchronization, that is, the sign is inverted between positive and negative as compared with the AC voltage from the power source. This code is inverted by the subsequent inverter, and the sinusoidal alternating voltage is generated. The deviation calculating means receives the generated sine wave AC voltage and the AC voltage from the power supply, and calculates the deviation between the two. Therefore, when a voltage fluctuation occurs in the AC voltage output from the power supply due to a power source trouble, the sine wave AC voltage input to the deviation calculating means does not vary. On the other hand, when the AC voltage output from the power supply fluctuates periodically, the sine wave AC generating means similarly generates a sine wave whose cycle fluctuates. For this reason, the deviation calculated by the deviation calculating means is small when the AC voltage is normally output from the power supply and when the periodic fluctuation occurs. When a trouble such as a momentary interruption or a power failure occurs in the AC voltage from the power supply, the deviation calculated by the deviation calculating means fluctuates greatly, and as a result, even if the power supply has periodic fluctuations, the voltage fluctuations of the power supply occur without delay. Can be detected.

When the power supply fluctuates, the voltage V4 also fluctuates in cycle.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a voltage fluctuation detecting device 1 for an AC power supply according to an embodiment of the present invention is a phase-locked loop (Phase-Locked) connected to an input terminal 11 of a commercial power supply (AC100V).
Loop: PLL) 13, a second phase-locked loop (PLL) 15 connected to the first phase-locked loop 13, and a second phase-locked loop 15
An inverter 17 connected to the inverter 17, a negative terminal connected to the inverter 17 and a positive terminal connected to the input terminal 11, and an output terminal connected to the output side of the differential amplifier 19. It consists of 21 and.

The first phase-locked loop 13 detects the phase difference between the phase of the internal oscillator and the phase of the input signal, and oscillates the oscillator so that the phase difference is always constant (90 degrees in this embodiment). A circuit that controls the frequency, the phase of the AC voltage V1 from the commercial power supply that corresponds to the input signal, and the output voltage from the loop 13.
The phase of V2 and the phase comparator (PC) 13a
And a phase error signal output from the phase comparator 13a is compared with a voltage controlled oscillator (VC).
O) 13b, the output voltage from the voltage controlled oscillator 13b is controlled so that the phase difference with the AC voltage V1 is 90 degrees, and is fed back to become the output voltage V2. ing.

The second phase-locked loop 15 is a circuit that, like the first phase-locked loop 13, controls the oscillation frequency of the oscillator so that the phase difference between the input and output signals is always constant, and corrects the output signal to a sine wave. , The phase of the output voltage V2 from the first phase locked loop 13 corresponding to the input signal and the phase of the output voltage V3 from the main loop 13 are compared by the phase comparator 15a, and the phase output from the phase comparator 15a Error signal is voltage controlled oscillator 15b
The output voltage V21 from the voltage controlled oscillator 15b is controlled so that the phase difference with the output voltage V21 becomes 90 degrees, and then the output voltage V21 is converted into a sine wave circuit (so-called low-pass filter). 15c is input to correct the sine wave, and the corrected sine wave is applied to the output voltage V3.
It has been configured to return so that.

The circuit of the above-mentioned second phase-locked loop 15 is configured such that the magnitude (voltage value) of the output voltage V3 matches the AC voltage voltage value that is always output from the commercial power supply. .

The inverter 17 is an inverting amplifier having an input / output of 1: 1 mainly composed of an OP amplifier, and in order to correct the phase difference 180 degrees deviated by the first phase locked loop 13 and the second phase locked loop 15,
The input voltage V3 is inverted and the voltage V4 is output.

The differential amplifier 19 mainly includes an OP amplifier, compares the output voltage V4 from the inverter 17 with the output voltage V1 from the commercial power supply,
The voltage V5, which is the difference between the two, is output to the output terminal 21.

Next, the operation of the voltage fluctuation detection device 1 for the AC power supply thus configured will be described with reference to the timing chart of FIG.

As shown in FIG. 2, when the AC voltage V1 is output from the commercial power supply, the first phase-locked loop 13 that has received the AC voltage V1.
Outputs a square wave voltage V2 whose phase is delayed by 90 degrees compared with the AC voltage V1. Further, the voltage controlled oscillator 15b of the second phase locked loop 15 outputs a square wave voltage V21 (not shown). Is output. The voltage V3 output from the second phase-locked loop 15 is the square wave of the output voltage V21 converted to a sine wave, and its phase is the output voltage of the first phase-locked loop 13.
It is 90 degrees behind V2. That is, the voltage
The phase difference between V3 and AC voltage V1 is 180 degrees. Thereafter, the inverter 17 corrects the phase difference, and the inverter 17 outputs the voltage V4. This voltage V4 is a signal whose phase is completely in agreement with the AC voltage V1 that is originally always output from the commercial power supply, and is always a constant sine wave AC even if the commercial power supply is interrupted at time t1. There is. In the differential amplifier 19 to which the voltage V4 and the AC voltage V1 from the commercial power source are input, the difference between the two is calculated, and has a waveform s for the deviation at the O level during normal operation and during the momentary interruption (time t1). Voltage signal V5
Is output.

Therefore, the voltage fluctuation detection device 1 for the AC power supply of this embodiment
Then, by detecting the voltage signal V5 from the output terminal 21, it is possible to detect a rapid voltage fluctuation caused by a power failure such as a power failure or a momentary interruption without a time delay regardless of the presence or absence of a cycle fluctuation.

Next, an uninterruptible power supply device using the voltage fluctuation detection device 1 for the AC power supply of this embodiment will be described with reference to FIG.

As shown in FIG. 3, the uninterruptible power supply 31 includes a storage battery 35 charged from a commercial power source by a charger 33 and an inverter that converts a DC voltage from the storage battery 35 into an AC voltage and outputs the AC voltage.
An emergency power source 39 equipped with 37 and an AC voltage from a commercial power source are always sent to the output terminal 41, and an AC voltage from the emergency power source is sent to the output terminal 41 when an AC voltage fluctuation such as a power failure or a momentary interruption occurs. A switching circuit 43 for switching to, a voltage fluctuation detecting device 1 connected to a commercial power source, a voltage signal V5 from the voltage fluctuation detecting device 1, and a switching circuit when a deviation of a predetermined value or more is found in the voltage signal V5. The electronic control circuit 45 switches 43 from the commercial power supply side to the emergency power supply 39 side.

The uninterruptible power supply 31 having such a configuration uses the voltage fluctuation detection device 1 of the AC power supply of this embodiment, and
It is possible to detect sudden voltage fluctuations due to momentary interruptions, etc. without any time delay regardless of the presence or absence of periodic fluctuations.Therefore, there is no need to temporarily stop the power supply as in the past, and always A stable power can be supplied.

In the above-described embodiment, the voltage (voltage value) input to the negative terminal of the differential amplifier 19 is set to the same value as the normal voltage value of the AC voltage from the commercial power source. Although the circuits of the first phase-locked loop 13 and the second phase-locked loop 15 are configured, instead of this, the first phase-locked loop 13, so that voltage signals of other magnitudes are input to the differential amplifier 19. The circuit of the second phase locked loop 15 may be configured, and in such a configuration, the voltage fluctuation of the power supply can be detected from the sudden change of the output signal of the differential amplifier 19.

Although one embodiment of the present invention has been described in detail above, the present invention is
It is needless to say that the present invention is not limited to the above-mentioned embodiment and can be implemented in various modes without departing from the scope of the present invention.

Effect of the Invention As described in detail above, the voltage fluctuation detecting device for an AC power supply of the present invention delays the voltage fluctuation when a sudden voltage fluctuation such as power failure or momentary interruption occurs due to a trouble in the power source. It can be detected instantly without.

Further, in particular, in the present invention, a sine wave alternating current, which serves as a reference in detecting a change in the alternating voltage, has a phase of 90% in the first PLL.
It is generated by a procedure of converting it to a square wave delayed by 90 degrees, converting it into a sine wave whose phase is further delayed by 90 degrees by the second PLL, and finally inverting it. Therefore, it is possible to generate a sine wave AC that is completely synchronized with the AC voltage from the power supply even if there is a periodic fluctuation, and by observing the difference between the two,
Regardless of the presence or absence of periodic fluctuations, it is possible to detect troubles such as instantaneous interruption of AC voltage from the power supply and power failure.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a circuit configuration of a voltage fluctuation detecting device for an AC power supply as an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the voltage fluctuation detecting device, and FIG.
FIG. 1 is a configuration diagram showing a circuit configuration of an uninterruptible power supply device using the voltage fluctuation detection device. 1 ... Voltage fluctuation detection device for AC power supply 13 ... First phase-locked loop 13a ... Phase comparator, 13b ... Voltage-controlled oscillator 15 ... Second phase-locked loop 15a ... Phase comparator, 15b ... Voltage Controlled oscillator 15c ... Sine wave conversion circuit 17 ... Inverter, 19 ... Differential amplifier

Claims (1)

[Claims] 1. A sine wave alternating current generating means for generating a sine wave alternating current voltage corresponding to a waveform of an alternating current voltage output from a constant voltage / constant frequency alternating current power source, and a sine generated by the sine wave alternating current generating means. In the AC power supply voltage fluctuation detection device for detecting a fluctuation of the AC voltage from the power supply, the deviation calculation means is provided that receives a wave AC voltage and an AC voltage from the power supply and calculates a deviation between the two. The generating means receives an AC voltage from the power source and has a phase with respect to this.
A first PLL that outputs a square wave delayed by 90 degrees; and a second PLL that receives the square wave from the first PLL and outputs a sine wave whose phase is delayed by 90 degrees with respect to the square wave. A voltage fluctuation detecting device for an AC power supply, comprising an inverter that receives a sine wave from a second PLL and inverts the sign of this voltage.