WO2003075430A1

WO2003075430A1 - Uninterruptible power supply

Info

Publication number: WO2003075430A1
Application number: PCT/JP2003/002273
Authority: WO
Inventors: Isao Amano; Masanobu Fujikura
Original assignee: Fuji Electric Co., Ltd.
Priority date: 2002-03-06
Filing date: 2003-02-28
Publication date: 2003-09-12
Also published as: JP2003259567A; AU2003211808A1

Abstract

An uninterruptible power supply for preventing an instantaneous stop when the operation is switched to an inverter operation by separating the voltage input side from the system if the input voltage lowers. The input voltage is supplied to the load through an AC switch (5) composed of thyristors connected in inverse-parallel to allow the thyristor through which a current of the same polarity as the input voltage to conduct. A parallel converter (12) connected to a feed line (LN) is allowed to carry out rectification operation to charge a battery (14). A series inverter (18) is allowed to carry out inverter operation using the battery (14) as an energy source. The output of the series inverter (18) is supplied in series to the feed line (LN) though a series transformer (19) to correct the output voltage applied to the load. If the input voltage lowers, the thyristor controlled to conduct is automatically cut off when a reverse bias is applied. When the operation of the parallel converter (12) is switched to an inverter operation, the switch (5) is in an off state. Therefore, any instantaneous stop of power supply to the load caused when a current flows through the AC switch (5) and a short-circuit part is prevented.

Description

Technical field

The present invention provides an uninterruptible power supply that supplies input power from an AC power supply or the like to a load, and supplies power to the load using energy stored in power storage means when the AC power supply or the like fails. The field concerning the device. Background art

As this type of uninterruptible power supply, for example, as shown in Fig. 8, a parallel converter connected in parallel to a power supply line for supplying input power supplied from a commercial power supply to a load, There has been proposed an uninterruptible power supply comprising: a series inverter having a power side connected in series to a power supply line;

In this uninterruptible power supply, as shown in FIG. 8, input power supplied from a commercial power supply or the like is output to a load via a power supply switch SW. In addition, a compensation circuit 10 is connected to a power supply line LN for supplying input power to a load. The compensation circuit 10 includes a parallel converter 12 having a rectifying function, an active filter function, and an inverter function, a battery 14, a capacitor 16, and a series inverter 18 connected in parallel in this order. It is configured.

The AC power side of the parallel converter 12 is connected in parallel via a reactor L 1 between a capacitor C 1 connected in parallel to the power supply line LN and a power supply line LN, and the reactor L 1 and capacitor C1 make up the LC filter.

The AC output side of the series inverter 18 is connected to the It is connected in series via a series transformer # 9 between the connection point with the capacitor C1 and the output terminal P out. Further, between the series transformer 19 and the output terminal P out, a capacitor C2 constituting a leakage inductance of the series transformer 19 and an LC filter is connected in parallel to the power supply line LN.

Then, the input voltage from the commercial power supply or the like input to the input terminal Pin of the power supply line LN is monitored, and when the input voltage is within the allowable range in which the preset input voltage can be regarded as normal, the input voltage is Judge as normal, and control the series inverter 18 so that the output voltage of the output terminal P out becomes the specified voltage, and keep the output voltage to the load at the specified voltage. In addition, the parallel converter 12 is operated as an active filter to reduce harmonics flowing from the input terminal Pin to the side of commercial power supply, etc., and to perform rectification as needed, to charge the battery 14 I do.

On the other hand, when the input voltage from the commercial power supply exceeds the allowable range, that is, when the input voltage exceeds the allowable range or falls below the allowable range, it is determined that the input voltage is abnormal, and the power supply switch SW is turned on. Shut off to disconnect the commercial power supply from the power supply line LN, and operate the parallel converter 12 as a backup. In other words, the parallel converter 12 is operated in reverse to generate AC power of a predetermined voltage in place of a commercial power supply or the like, and supplies this to the load. In addition, the series inverter 18 is continuously controlled in the same manner so that the output voltage to the load becomes the specified voltage.

By performing the above processing, a predetermined power supply can be continuously performed to the load even when an abnormality occurs in the commercial power supply or the like. Here, as described above, when the input voltage exceeds the allowable range, it is determined that the input voltage is abnormal, and the power supply switch SW is shut off.However, the input voltage actually becomes an abnormal value. After the power supply switch SW is actually turned off and the commercial power supply is disconnected from the power supply line LN, it takes several A time delay occurs.

Therefore, for example, when the input voltage drops due to a short circuit or the like, the parallel converter 12 is controlled to perform the backup operation by detecting the drop of the input voltage, and the parallel converter 12 is turned off. Even if it operates as an inverter, an excessive current flows through the short-circuited portion via the power supply switch SW until the power supply switch SW is actually turned off, so the parallel converter 12 Cannot be maintained. At this time, although the series inverter 18 performs correction so that the output voltage to the load becomes the specified voltage, the output voltage must be maintained at the specified voltage because the range that can be corrected is limited. However, the output voltage to the load decreases, resulting in a problem that the voltage temporarily drops and an instantaneous power failure occurs.

In addition, when the parallel converter 12 is operated as an active filter, a complicated operation is required to calculate a harmonic component. Also, since the active filter needs to change its output current steeply, the parallel converter 12 and the control device for controlling the same require a command value for changing the output current of the parallel converter 12 steeply. There is a problem that high current control performance is required, which can follow the current. '

In view of the above, the present invention has been made in view of the above-mentioned conventional unsolved problem, and it is possible to avoid an instantaneous stop of an output voltage when disconnecting a voltage input side due to a decrease in an input voltage. An object of the present invention is to provide an uninterruptible power supply capable of reducing the processing load of processing and removing harmonic components without requiring advanced processing performance

Disclosure of the invention

To achieve the above object, the invention of claim 1 is interposed in a power supply line and A power supply switch composed of two thyristors connected in antiparallel, a parallel converter connected in parallel between the power supply switch and the output end of the power supply line, and a power storage means connected to the parallel converter A series transformer connected in series between a connection point of the power supply line with the parallel converter and the output terminal, and an AC output voltage of the output terminal connected to the series transformer and having a predetermined value. A series inverter that adjusts the AC output voltage using the power storage unit as an energy source, a voltage abnormality detection unit that detects an input voltage abnormality of AC power input to an input terminal of the power supply line, Control means for controlling the power supply switch and the parallel converter in accordance with the detection result of the voltage abnormality detection means, wherein the control means comprises: When no abnormality is detected in step (a), the power supply switch is controlled so that a thyristor through which a current having the same polarity as the input voltage to the input terminal is ignited, and the parallel converter is controlled to control the power storage means. The current flowing through the parallel converter is adjusted so that the energy becomes a specified value and the input power factor of the AC power input to the input terminal becomes 1, and when the voltage abnormality detecting means detects an abnormality, The power supply switch is controlled to be cut off, and the parallel converter is controlled so as to output AC power of a predetermined voltage to the power supply line using the power storage means as an energy source.

According to the first aspect of the present invention, the power supply switch inserted in the power supply line for supplying AC power to the load is constituted by a thyristor connected in anti-parallel, and the input voltage of the input terminal to the input terminal of the power supply line is reduced. The two thyristors are alternately turned on and off in accordance with the polarity of the input voltage so that the thyristor that allows the current of the same polarity to be turned on is turned on. Controlled to be "1". Note that this power factor does not necessarily have to be “1”, and the thyristor that is turned on according to the polarity of the input voltage is turned on due to the large phase difference between the input current and voltage. Automatically turns off despite being Any power factor may be used as long as the power factor can be avoided. 'Therefore, when the input voltage to the input end of the power supply line exceeds the allowable range, when this is detected, the parallel converter connected in parallel to the power supply line outputs AC power of a predetermined voltage. In addition, the series inverter connected to the power supply line via a series transformer operates so that the AC output voltage to the load becomes a predetermined value. When the reverse bias is applied to the thyristor, the thyristor automatically turns off when the input voltage drops due to a power failure or the like. The output voltage to is prevented from being momentarily stopped, and the output voltage is maintained at the predetermined value.

Further, the invention according to claim 2 includes a power supply switch inserted in a power supply line, a parallel converter connected in parallel between the power supply switch and an output end of the power supply line, A power storage means connected thereto, a series transformer connected in series between a connection point of the power supply line with the parallel converter and the output terminal, and an AC output voltage connected to the series transformer and at the output terminal. A series inverter that adjusts the AC output voltage using the power storage means as an energy source so as to have a predetermined value, and a connection point between the power supply line and the parallel converter and the power supply switch. An input reactor, voltage abnormality detection means for detecting an input voltage abnormality of AC power input to an input end of the power supply line, and the power supply according to a detection result of the voltage abnormality detection means. Control means for controlling the switch and the parallel converter, wherein the control means controls conduction of the power supply switch when the voltage abnormality detection means does not detect an abnormality, and controls the parallel converter. Controlling the current flowing through the input reactor so that the energy of the power storage means becomes a specified value. When the voltage abnormality detection means detects an abnormality, the power supply switch is cut off and the power storage means is controlled. As an energy source, The parallel converter is controlled so as to output high-voltage AC power to the power supply line.

According to the second aspect of the present invention, the parallel converter is controlled so that, for example, the current flowing through the input reactor becomes a sinusoidal current, and the AC power from a commercial power supply or the like is balanced with the power supplied to the load. By adjusting the amplitude of the sinusoidal current, the current flowing through the input reactor is controlled such that the energy of the power storage means becomes a specified value. At this time, the current flowing through the input reactor is controlled to be sinusoidal, so if the output current to the load contains harmonic components, the harmonic current will flow to the parallel converter, It does not leak to the commercial power supply.

If the input voltage to the input end of the power supply line exceeds the allowable range due to a power failure or the like, the parallel converter operates as an inverter to generate AC power. At this time, since the input reactor is interposed between the parallel converter of the power supply line and the power supply switch, the AC current generated by the parallel converter is suppressed from flowing to the commercial power supply or the like. In addition, since the output voltage is corrected by the series inverter so that the output voltage becomes the command value, the output voltage to the load does not enter an instantaneous blackout state, and the output voltage is maintained at the command value.

Further, the invention according to claim 3 is characterized in that a power supply switch composed of two thyristors inserted in a power supply line and connected in antiparallel is connected in parallel between the power supply switch and an output terminal of the power supply line. A parallel converter, a power storage means connected to the parallel converter, a connection point between the power supply line and the parallel converter, and a series transformer connected in series between the output terminals. A connection between a series inverter that is connected and adjusts the output voltage using the power storage means as an energy source so that the AC output voltage at the output terminal becomes a predetermined value, and a connection between the parallel converter and the power supply line. The input relay inserted between the point and the feed switch A voltage abnormality detecting means for detecting an input voltage abnormality of AC power input to an input terminal of the power supply line; a power supply switch and the parallel compensator according to a detection result of the voltage abnormality detection means; And a control means for controlling the control means, when the voltage abnormality detection means does not detect an abnormality, the control means is configured to ignite a thyristor through which a current having the same polarity as an input voltage to the input terminal is ignited. Controlling the power supply switch and controlling the parallel converter to adjust the current flowing through the input reactor so that the energy of the power storage means becomes a specified value and the current flowing through the input reactor has a power factor of 1; When an abnormality is detected by the voltage abnormality detecting means, the power supply switch is cut off and controlled to a predetermined voltage by using the power storage means as an energy source. It is characterized by controlling the parallel converter evening to output flow power to the power supply line.

According to the third aspect of the present invention, the parallel converter is controlled so that, for example, the current flowing through the input reactor is substantially a sine-wave current having a power factor of “1”, and AC power from a commercial power supply or the like is supplied to the load. By adjusting the amplitude of the sinusoidal current so as to balance the supplied power, the current flowing through the input reactor is controlled so that the energy of the power storage means becomes a specified value. At this time, the current flowing through the input reactor is controlled to be sinusoidal, so if the output current to the load contains a harmonic component, the harmonic current will flow to the parallel converter. It does not flow to the commercial power supply.

The feed switch inserted in the feed line for supplying AC power to the load is composed of a thyristor connected in anti-parallel, and has the same polarity as the polarity of the input voltage to the input end of the feed line. The two thyristors are alternately turned on and off in accordance with the polarity of the input voltage so that the thyristor through which the current flows is turned on.At this time, the current flowing through the input reactor is controlled by the parallel comparator. The rate is controlled to be "1". This power factor must always be "1". 273

It is not necessary, and the thyristor, which is turned on according to the polarity of the input voltage, is automatically turned off despite the fact that it is turned on due to the large phase difference between the input current and the voltage. Any power factor may be used as long as the power factor can be avoided. Therefore, when the input voltage to the input end to the power supply line exceeds the allowable range, the parallel converter connected in parallel to the power supply line operates to output AC power of a predetermined voltage, and the power supply line The series inverter connected via a series transformer operates so that the output voltage to the load becomes a predetermined value, and if the input voltage decreases, the When the reverse bias is applied to the thyristor, the thyristor automatically turns off, so even if the input voltage drops due to a power failure or the like, the output voltage to the load will be instantaneous. A stop condition is avoided, and the output voltage is maintained at a predetermined value.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a circuit diagram illustrating an example of the uninterruptible power supply according to the first embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration of the AC switch control unit 22 of FIG.

FIG. 3 is a block diagram showing a functional configuration of the parallel converter overnight controller 24 of FIG.

FIG. 4 is a block diagram showing a functional configuration of the serial inverter controller 26 of FIG.

FIG. 5 is a circuit diagram illustrating an example of the uninterruptible power supply according to the second embodiment of the present invention.

FIG. 6 is a block diagram showing a functional configuration of the parallel converter overnight controller 24a of FIG. is there. '

FIG. 7 is a circuit diagram illustrating an example of the uninterruptible power supply according to the third embodiment of the present invention. '

FIG. 8 is a circuit diagram showing an example of a conventional uninterruptible power supply. Explanation of reference numerals

5 AC switch, 5a, 5b thyristor, 6 relay switch, 10 compensation circuit, 12 parallel comparator, 14 battery, 16 capacitor, 18 series inverter, 19 series transformer, 20 control circuit, 22 AC switch control section, 23 BEST MODE FOR CARRYING OUT THE INVENTIONRelease switch control unit, 24, 24a parallel converter control unit, 26 series inverter control unit

Hereinafter, embodiments of the present invention will be described.

First, a first embodiment will be described.

FIG. 1 is a circuit diagram illustrating an example of the uninterruptible power supply according to the first embodiment.

As shown in Fig. 1, an AC switch 5 is provided on the power supply line LN between the input terminal Pin connected to a commercial power supply or the like and the output terminal Pout connected to the load, and the AC switch 5 and the output terminal Pout Is connected to the compensation circuit 10. The AC switch 5 includes a pair of thyristors 5a and 5b connected in anti-parallel. The compensation circuit 10 includes a parallel converter 12, a battery 14, a capacitor 16, and a series inverter 18 in this order, in the same manner as the conventional uninterruptible power supply shown in FIG. It is configured to be connected to. And the parallel converter The evening 12 and the series inverter 18 are each formed of a known full-bridge circuit in which, for example, a switching element and a diode connected in anti-parallel to each other are connected in series two by two.

The AC power side of the parallel converter 12 is connected via a reactor L1 between a connection point between a capacitor C1 connected in parallel to the power supply line LN and a capacitor C1 of the power supply line LN. The reactor L1 and the capacitor C1 constitute an LC filter.

The AC output side of the series inverter 18 is connected to an isolation transformer in which a secondary winding is inserted between a connection point of the power supply line LN and the capacitor C1 and an output terminal P out. Connected to the power supply line LN via a series transformer 19. Further, a capacitor C2 is connected in parallel to a power supply line LN between the series transformer 19 and the output terminal Pout, and an LC filter is formed by the capacitor C2 and the leakage inductance of the series transformer 19. Make up.

The AC switch 5, the parallel converter 12 and the serial inverter 18 are driven and controlled by a control circuit 20.

The control circuit 20 controls an AC switch control unit 22 that drives and controls the AC switch 5, a parallel converter control unit 24 that controls the parallel converter 12 and a serial converter 18 that controls the series inverter 18. And a serial receiver 26. FIG. 2 is a block diagram showing a functional configuration of the AC switch control unit 22. The AC switch control unit 22 detects a comparator 22a and a rising edge of an output signal of the comparator 22a. And a falling edge detector 22c for detecting a falling edge of the output signal of the comparator 22a. The non-inverting input terminal of the comparator 22a has an input voltage detector 32 connected to a power supply line LN between the input terminal Pin and the AC switch 5 and detecting an input voltage from a commercial power supply or the like. The detected input voltage Vin is applied, and the inverted input terminal A reference voltage for detecting the phase of the input voltage Vin is applied to the element. The comparator 22a outputs a HIGH-level signal when the input voltage is higher than the reference voltage, and outputs a LOW-level signal when the input voltage is lower than the reference voltage.

On the other hand, when detecting the rising edge of the output signal of the comparator 22a, the rising edge detector 22b detects the current flowing from the input terminal Pin to the output terminal Pout of the AC switch 5. Control thyristor 5a, which allows flow, to the on state. Conversely, when the falling edge detector 22c detects the falling edge of the output signal of the comparator 22a, the falling edge detector 22c outputs a signal from the output terminal Pout to the input terminal Pin of the AC switch 5. The thyristor 5b that allows current flow is controlled to the ON state. That is, the AC switch control section 22 turns on and off the thyristors 5a and 5b alternately in accordance with the polarity of the input voltage Vin. FIG. 3 is a block diagram showing a functional configuration of the parallel converter control unit 24. As shown in FIG. 3, the difference between the DC voltage command value E dc *, which is the target value of the voltage across the capacitor 16, and the DC voltage E dc across the capacitor 16 detected by the charging voltage detector 34. Is detected by the arithmetic unit 41, a voltage adjustment operation such as PI control is performed in the voltage adjuster 42, and the operation result is multiplied by the reference sine wave signal sincot by the arithmetic unit 43. You.

The reference sine wave signal s incot is a signal whose phase is synchronized with the input voltage Vin, and the amplitude thereof is set arbitrarily. Set to the corresponding value.

Then, a difference value between the calculation result of the calculator 43 and the calculation result of the harmonic component extraction calculator 44 is calculated by the calculator 45. Based on the output current l out detected by the output current / voltage detector 36 connected between the series transformer 19 and the output terminal P out, the harmonic component extraction / calculation unit 44 uses a known procedure. Therefore harmonic Extract wave components. The difference between the difference value calculated by the arithmetic unit 45 and the parallel converter current Ipara, which is the current flowing through the parallel converter 12 and detected by the parallel converter current detector 38, is calculated by the arithmetic unit 46. Is calculated. Next, a current adjustment operation for making the difference value zero is performed in the current adjuster 47, and the operation result is input to the arithmetic operation unit 49 via the cutoff switch 48, and this and the reference sine wave The signal δϊηωt is added. The reference sine wave signal sinwt is a signal whose phase is synchronized with the input voltage Vin, and its amplitude is set according to, for example, the rated voltage to the load.

Then, a pulse signal is generated in the PWM control section 50 based on the addition result. At this time, the parallel converter 12 is operated to perform a rectifying operation and an active fill operation so that the DC voltage E dc matches the DC voltage command value E dc *, and the input power factor becomes substantially “1”. A pulse signal is generated, and the switching elements of the parallel converter 12 are controlled based on the pulse signal.

In other words, the current value flowing through the parallel converter 12 necessary to match the DC voltage E dc with the DC voltage command value E dc * and the parallel converter 1 2 required to cancel the harmonic components of the output current The feedback control is performed so that the sum of the current value and the parallel converter current I par a is calculated.

Note that the input power factor is desirably “1”, but is not necessarily “1”. In other words, since the thyristors 5a and 5b of the AC switch 5 are controlled according to the polarity of the input voltage, if the input power factor is not "1", the current flowing through the thyristor that is turned on is controlled. When the value becomes zero, the thyristor is automatically turned off, and the current stops flowing thereafter. Therefore, it is sufficient that the power factor is such that this can be avoided. If the phase difference between the input voltage and the input current is about 30 °, that is, if the power factor is about 0.866 or more, If you have No.

The cutoff switch 48 is turned on when the input voltage Vin detected by the input voltage detector 32 is within a preset allowable range in which the input voltage can be regarded as normal. When the input voltage exceeds the permissible range, that is, when the input voltage exceeds or falls below the permissible range, it is controlled to be in a cutoff state as a voltage abnormality.

When the input voltage is determined to be abnormal based on the input voltage Vin detected by the input voltage detector 32, and the cutoff switch 48 is controlled to be in the cutoff state, the PWM control unit 5 0, a pulse signal for operating the parallel converter 12 in an inverting mode is generated based on, for example, a reference sine wave signal sinot according to the rated voltage to the load. 2 controls each switching element. That is, feedforward control is performed according to the reference sine wave signal sinwt.

FIG. 4 is a block diagram showing a functional configuration of the serial inverter control unit 26. As shown in FIG. 4, the difference between the preset output voltage command value Vout * to the load and the output voltage Vou 〖to the load detected by the output current voltage detector 36 is calculated by the arithmetic unit 5 1 Based on this difference value, for example, voltage adjustment calculation such as PI control is performed by the voltage adjuster 52, and based on this, the PWM controller 53 causes the series inverter 18 to operate as an inverter. Is generated, and each switching element of the serial inverter 18 is controlled. That is, feedback control is performed so that the output voltage Vout becomes the output voltage command value Vout *.

The serial inverter control section 26 performs the inverter operation irrespective of whether or not the input voltage is abnormal.

Next, the operation of the first embodiment will be described.

If the input voltage from the commercial power supply is normal, the input voltage detector 32 detects it. Since the input voltage Vin falls within the allowable range, the control circuit 20 determines that the input voltage from the commercial power supply is normal. Therefore, the AC switch control unit 22 alternately controls the thyristors 5a and 5b to the conducting state according to the phase of the input voltage Vin.

Therefore, the power supplied from the commercial power supply or the like is supplied to the load via the AC switch 5, and the series inverter controller 26 sets the output voltage Vout to the load to be the output voltage command value Vout *. The DC power of the battery 14 and the capacitor 16 is changed to AC power, which is applied in series to the power supply line LN via the series transformer 19, The output voltage Vout to the load will be maintained at the output voltage command value Vout *.

Also, since the input voltage is normal, the parallel converter control unit 24 extracts the harmonic components included in the output current l out to the load, and outputs the parallel converter current I para and the output current I out The rectifying operation of the parallel converter 12 and the active filter operation are performed so that a current value corresponding to a harmonic component of the capacitor 16 and a voltage value that allows the voltage E dc across the capacitor 16 to be a DC voltage command value E dc * are obtained. Let me do it. As a result, the battery 14 is charged, and the harmonic component generated in the load is absorbed by the parallel converter 12, so that the harmonic current does not flow out to the commercial power supply.

From this state, when a short circuit or the like occurs on the commercial power supply side and the input voltage Vin decreases, when the reverse bias is applied to the thyristor 5a or 5b that is controlled to conduct, The thyristor on which conduction is controlled is automatically shut off.

The control circuit 20 determines that the input voltage is abnormal when the input voltage Vin exceeds the allowable range. The series inverter control unit 26 continues to control the series inverter 18 in the same manner as before so that the output voltage Vout is changed to the output voltage command value V Performs an inverting motion to keep out *. In addition, the parallel controller

In 24, since the voltage abnormality of the input voltage was detected, the cutoff switch 48 was controlled to be in the cutoff state, and the specified voltage corresponding to the normal input voltage was controlled based on the reference sine wave signal sinwt. To control the parallel compiler 1 and 2 to generate. As a result, the DC power of the battery 14 and the capacitor 16 is converted into AC power and supplied to the load via the power supply line LN.

Here, when the input voltage decreases, the thyristor of which the conduction is controlled among the thyristors constituting the AC switch 5 is at the time when the reverse bias is applied as the input voltage decreases. When the input voltage exceeds the allowable range, a voltage abnormality is automatically detected, and then the parallel converter 12 is controlled to operate overnight. At this time, since the other thyristor is controlled to be cut off, when the reverse bias is applied to the thyristor whose conduction is controlled, the input terminal Pin side of the AC switch 5 is connected to the power supply line LN. Will be disconnected from

Therefore, after that, when the parallel converter 12 is switched from the rectifying operation and the active filter operation to the backup operation, the input terminal Pin side is already disconnected from the power supply line LN, so that the input terminal Pin becomes excessive through the short circuit. No current flows, and the parallel converter 12 generates AC power of a predetermined voltage and supplies it to the load side. Therefore, it is possible to prevent the output voltage Vout to the load from being in an instantaneous blackout state.

In the first embodiment, the AC switch 5 is composed of a thyristor and is alternately turned on and off in synchronization with the polarity of the input voltage Vin. However, since the parallel converters 1 and 2 are operated as active filters and the input power factor is controlled to be "1", the flow of harmonic current to the commercial power supply is suppressed. Can be input along with It is possible to prevent the thyristor from being turned off and the AC switch 5 from being cut off even though no power failure has occurred due to the power factor not being "1".

Next, a second embodiment will be described.

FIG. 5 is a circuit diagram illustrating an example of an uninterruptible power supply according to the second embodiment. In the second embodiment, the power supply line LN is provided with the relay switch 6, and the AC power input to the input terminal Pin is supplied to the load from the output terminal Pout via the relay switch 6. It has become. An input reactor Lin is inserted between the relay switch 6 of the power supply line LN and the output terminal Pout, and a capacitor C1 is connected to the power supply line LN between the input reactor Lin and the relay switch 6. The LC filter is composed of the input reactor Lin and capacitor C1 connected in parallel.

Further, a compensation circuit 10 configured in the same manner as in the first embodiment is connected to the power supply line LN between the input reactor Lin and the output terminal Pout, and the AC power of the parallel converter 12 of the compensation circuit 10 is Is connected between the input reactor Lin and the output terminal Pout, and the AC power side of the series inverter 18 is connected to the power supply line LN via the series transformer 19 as in the first embodiment. ing. Further, a capacitor C2 is connected in parallel to the power supply line LN between the series transformer 19 and the output terminal Pout, and an LC filter is configured by the leakage inductance of the series transformer 19 and the capacitor C2.

The control circuit 20 controls the driving of the relay switch 6, the parallel converter 12, and the serial inverter 18.

The control circuit 20 according to the second embodiment includes a relay switch control unit 23 that controls the drive of the relay switch 6, a parallel converter control unit 24a that controls the parallel converter 12, and a serial driver. Evening 18 is the first form of implementation A series inverter control unit 26 for controlling in the same manner as in the first embodiment is provided.

When the input voltage Vin detected by the input voltage detector 32 that detects an input voltage from a commercial power supply or the like is within the allowable range set in advance, the relay switch control unit 23 includes: The relay switch 6 is controlled to be in a conductive state, and when the input voltage Vin exceeds the allowable range, it is considered that the input voltage is abnormal, and the relay switch 6 is controlled to be in a cut-off state.

FIG. 6 is a block diagram showing a functional configuration of the parallel converter overnight controller 24a. As shown in FIG. 6, the difference between the DC voltage command value E dc *, which is the target value of the DC voltage across capacitor 16, and the voltage across capacitor 16 detected by charging voltage detector 34 is Detected by arithmetic unit 61. Then, based on this difference value, a voltage adjustment operation such as PI control is performed in the voltage adjuster 62, and the operation result is multiplied by the reference sine wave signal sincot by the arithmetic unit 63. Note that the reference sine wave signal sincot is a signal whose phase is synchronized with the input voltage Vin as in the first embodiment, and the amplitude of which is, for example, the input voltage supplied from a commercial power supply or the like. Is set to a value corresponding to the amplitude of the rated voltage of.

Then, a difference value between the multiplication result in the calculator 63 and the input current Iin detected in the input current detector 33 is calculated in the calculator 64, and this difference value is set to zero. The current adjustment calculation is performed by the current regulator 65, and the calculation result is input to the calculator 67 via the cutoff switch 66, and this and the reference sine wave signal sin ωt are added. . The reference sine wave signal s in cot is a signal whose phase is synchronized with the input voltage Vin as in the first embodiment, and its amplitude is set according to, for example, the rated voltage to the load. .

Then, a pulse signal for rectifying the parallel converter 12 is generated in the PWM control unit 68 based on the calculation result in the arithmetic unit 67, and each switching element of the parallel converter 12 is turned on. Controlled. That is, the input current I in Feedback control is performed so that the current value corresponds to the difference value between the flow voltage E dc and the DC voltage command value E dc * and the power factor of the input current I in becomes “1”. In the second embodiment, the power factor of the input current Im does not necessarily need to be “1”. However, in order to prevent the harmonic component from flowing to the commercial power supply, “1” is used. Is desirable.

The cut-off switch 66 is controlled to be in a conductive state when the input voltage is within a preset allowable range in which the input voltage can be considered to be normal, and the input voltage is controlled to fall within the allowable range. When the voltage falls below the lower limit, it is controlled to shut off as an abnormal voltage.

Then, based on the input voltage Vin detected by the input voltage detector 32, the input voltage is determined to be abnormal, and when the cut-off switch 66 is controlled to be in the cut-off state, the PWM control unit 6 In 8, a pulse signal for operating the parallel converter 12 is operated based on the reference sine wave signal sincot, and each switching element of the parallel converter 12 is controlled based on the pulse signal. . That is, feedforward control is performed based on the reference sine wave signal sinot. Note that, when the parallel converter 12 is operated in an inverting mode when the input voltage drops, the voltage difference between the input voltage and the output voltage of the parallel converter 12 is applied to the input reactor Lin, and flows to the input reactor Lin. Since the current increases with time, the inductance value of the input reactor L in is set so that this reactor current can be kept within the allowable range.

Next, the operation of the second embodiment will be described.

Now, if the input voltage from the commercial power supply or the like is normal, the input voltage Vin detected by the input voltage detector 32 falls within a predetermined allowable range. Is determined to be normal, and the relay switch control section 23 controls the relay switch 6 to a conductive state. Therefore, it was supplied from a commercial power source, etc. The power is supplied to the load via the relay switch 6, and the series inverter controller 26 controls the series inverter 18 so that the output voltage Vout to the load becomes the output voltage command value Vout *. Since the DC power of the battery 14 and the capacitor 16 is converted to AC power, the DC power of the battery 14 and the capacitor 16 is applied in series to the power supply line LN via the series transformer 19, and the output voltage Vout to the load becomes The output voltage command value will be maintained at V ou 〖*.

Also, since the input voltage is normal in the parallel converter control section 24a, the input reactor L depends on the current value necessary to maintain the voltage across the capacitor 16 at the DC voltage command value E dc *. in, and the input current I in detected by the input current detector 3 3 matches this command value, and furthermore, the input current I in has a power factor of 1. Feedback control of parallel converters 1 and 2.

For this reason, the energy of the battery 14 and the capacitor 16 is supplied to the load as a supply current to the load via the parallel converter 12, and when the DC voltage E dc decreases accordingly, the DC voltage command value E d And an actual DC voltage E dc, a current flows through the input reactor L in .At this time, the input current I in is controlled to have a power factor of 1, so the output current I o ′ If ut includes an ineffective component such as a harmonic component, the ineffective component flows to the parallel converter 12 and is absorbed there. That is, the parallel converter 2 eventually functions as an active filter.

In this state, if a short circuit or the like occurs on the commercial power supply side and the input voltage Vin exceeds the allowable range, the relay switch control section 23 controls the relay switch 6 to the cut-off state on the date when it is detected. . In addition, the serial inverter control unit 26 continues to perform the inverter operation to keep the output voltage Vout constant as before, but the parallel converter 12 detects an abnormal input voltage. That Then, the cut-off switch 66 is operated to be in the cut-off state, and based on the reference sine wave signal s incot, the AC power of the specified voltage corresponding to the supply voltage of the commercial power supply 1 from the DC power of the battery 14 and the capacitor 16. The parallel converters 12 are controlled so as to generate. As a result, the DC power of the battery 14 and the capacitor 16 is converted into AC power and supplied to the load via the power supply line LN.

Here, if a voltage abnormality of the input voltage is detected, the relay switch 6 is controlled to be in the cut-off state, and the parallel converter 1 and 2 operate instantly, but the relay switch 6 actually operates. Since it takes some time to be in the cutoff state, the inverse operation of the parallel converter 12 starts before the relay switch 6 becomes in the cutoff state.

At this time, the input reactor Lin is inserted between the connection point of the parallel converters 12 and the feed line LN and the relay switch 6, and the input reactor Lin acts as a current limiting reactor. Short-circuit current flowing to the commercial power side from night 12 is suppressed. Therefore, AC power of a predetermined voltage is supplied to the power supply line LN, and the output voltage Vout to the load is corrected by the series inverter 18 so that the output voltage Vout becomes the output voltage command value Vout *. Therefore, even if the operation of the parallel converter 12 is switched to the inverting operation due to a voltage abnormality in the input voltage due to a short circuit or the like, the voltage is continuously supplied to the load. The AC power whose value is the output voltage command value V out * is output.

At this time, when the parallel converters 12 start the impeller operation, a voltage difference occurs between the commercial power supply side of the input reactor L in and the parallel converter side, and this voltage difference is applied to both ends of the input reactor L in. However, the current flowing through the input reactor Lin increases with time, but there is no problem because the inductance value of the input reactor Lin is set in consideration of the reactor current. Therefore, in this case as well, it is possible to prevent instantaneous blackout as in the first embodiment, and in the second embodiment, the input current Iin is set to a predetermined current value. In addition, since the control is performed so that the power factor becomes 1, it is possible to prevent the harmonic current from flowing to the commercial power supply.

Further, unlike the first embodiment, since there is no need to extract harmonic components, there is no need to perform complicated calculations for extracting harmonic components, and control can be performed with simple calculations. However, the processing time can be reduced, and the current flowing through the parallel compander 12 does not need to be sharply changed. Therefore, the present invention can be realized without requiring high processing performance.

Next, a third embodiment of the present invention will be described.

The third embodiment is a combination of the first and second embodiments.

That is, as shown in FIG. 7, the uninterruptible power supply according to the third embodiment differs from the uninterruptible power supply according to the second embodiment shown in FIG. The AC switch 5 according to the first embodiment is interposed, and the AC switch control unit 22 according to the first embodiment is provided instead of the re-switch control unit 23 of the compensation circuit 10. . The parallel converter overnight controller 24a controls the parallel converter 12 so that the power factor of the input current Iin becomes "1". In this case, the power factor is always "1". However, as in the first embodiment, the thyristor is automatically activated even though the input voltage has not dropped due to the input power factor not being “1”. It is sufficient that the power factor is such that it can be prevented from being turned off.

Therefore, in the third embodiment, when the input voltage Vin from the commercial power supply or the like is normal, the thyristors 5a and 5b are turned on alternately according to the polarity of the input voltage Vin. The input power supplied from a commercial power source 273

22 In addition to being supplied to the load via the switch 5, the series inverter 18 performs an inverter operation so that the output voltage Vout to the load becomes the specified voltage, and as a result, the output voltage Vout to the load Is maintained at a specified voltage.

Also, the command value of the input current Iin is set according to the difference between the voltage E dc across the capacitor 16 and the DC voltage command value Ed, and the power factor of the current flowing through the reactor L in becomes 1 Then, the command value of the current of the input current Iin is determined, and the parallel converter 12 is controlled so that the command value matches the input current Iin. The current is supplied to the load via the parallel converter 12 and when the DC voltage E dc decreases, the input current I in corresponding to the difference from the DC voltage command value Ed flows through the reactor L in. At this time, the input current Iin is controlled so that the power factor becomes 1, so that the harmonic component included in the output current Iout flows through the parallel converter 12 and the harmonic current becomes It does not flow to the power supply. ·

In this state, when a short circuit or the like occurs on the commercial power supply 1 side, the input voltage Vin decreases and the reverse bias is applied to the thyristor 5a or 5b that is controlled to conduct. At this point, the thyristor is automatically cut off, and the thyristor whose conduction is not controlled at this time is in the cutoff state. At this point, the commercial power supply is disconnected from the power supply line LN. Then, when the input voltage Vin decreases and exceeds the allowable range, the parallel converter 12 performs a backup operation of generating AC power from the DC power of the battery 14 and the capacitor 16 based on the reference sine wave signal sincot. At this point, however, since the AC switch 5 is in the cutoff state and the input reactor Lin is inserted, the short-circuit current from the parallel converter 12 to the commercial power supply is suppressed. Therefore, a predetermined AC voltage is generated by the parallel converter 12 and is corrected to the specified voltage by the serial inverter 18, so that the specified voltage is continuously supplied to the load. Become.

Therefore, the same operation and effect as those of the first and second embodiments can be obtained, and the AC switch 5 that automatically shuts off as the input voltage decreases is used. The reactor value of in can be set to a smaller value.

In each of the above embodiments, the case where the parallel converter 12 and the serial inverter 18 are configured by a full bridge circuit composed of a switching element and a diode connected in antiparallel to the switching element has been described. For example, the present invention can be applied to a half-bridge circuit.

Here, in each of the above-described embodiments, the AC switch 5 or the relay switch 6 corresponds to the power supply switch, the parallel converter 12 corresponds to the parallel converter, and the notch 14 and the capacitor 16 correspond to the power storage means. The serial inverter 18 and the serial inverter controller 26 correspond to the serial inverter, the input voltage detector 32 corresponds to the voltage abnormality detecting means, and the AC switch controller 22 or the relay switch. The controller 23 and the parallel converter controller 24 or 24a correspond to the control means. Industrial applicability,

As described above, according to the uninterruptible power supply according to claim 1 of the present invention, the power supply switch inserted in the power supply line is configured by two thyristors connected in antiparallel, and the power supply line Since the power factor is controlled so that the input power factor of the AC power is 1 by turning on and off alternately according to the polarity of the input voltage to the input terminal of the input terminal, when the input voltage drops due to a power failure, etc. The power supply switch can be automatically turned off when a reverse bias is applied to the thyristor before the parallel converter starts the inverting operation. At this time, the series inverter operates using the power storage means as an energy source so that the AC output voltage becomes a command value. Therefore, the voltage value of the AC output can be maintained at the command value, and the output voltage can be prevented from being in a momentary power failure state.

Further, according to the uninterruptible power supply according to the second aspect, the current flowing through the input reactor is controlled by the parallel converter so that the energy of the power storage means becomes a specified value. Since the high-frequency component of the current flows, the high-frequency component can be absorbed by the parallel converter with simple control, and can be realized without requiring a high-performance processing device. In addition, since an input reactor is installed between the parallel converter on the power supply line and the power supply switch, even if the input voltage to the input end of the power supply line decreases due to a power failure or the like, the AC current generated by the parallel converter Is suppressed from flowing to the power input side, and the series inverter operates using the power storage means as an energy source so that the AC output voltage becomes the command value, so that the voltage value of the AC output is maintained at the command value. The output voltage can be prevented from being in a momentary power failure state.

According to the uninterruptible power supply according to claim 3, the power supply switch inserted into the power supply line is constituted by two thyristors connected in anti-parallel, and alternately according to the polarity of the input voltage. Since the power supply is turned on and off and the current flowing through the input reactor is controlled to have a power factor of 1, when the input voltage drops due to a power failure or the like, the thyristor current before the parallel converter starts inverting operation The power supply switch can be automatically turned off when a reverse bias is applied to the power supply. Also, at this time, since the AC output voltage is operated at a predetermined value by using the power storage means as an energy source, the AC output can be maintained at a predetermined voltage value, and the output voltage is temporarily stopped. The state can be avoided. In addition, since the parallel converter was operated so that the energy of the power storage means became the specified value and the input power factor of the AC power was 1, the parallel converter was eventually operated. The high frequency component of the output current flows, and the high frequency component can be absorbed by the parallel converter with simple control.

Claims

'Scope of Claim 1. Power supply switch consisting of two thyristors inserted in the power supply line and connected in anti-parallel,

A parallel converter connected in parallel between the power supply switch and the output end of the power supply line;

Power storage means connected to the parallel converter,

A series transformer connected in series between a connection point of the power supply line with the parallel converter and the output end,

A series inverter connected to the series transformer and adjusting the AC output voltage using the power storage means as an energy source such that the AC output voltage at the output terminal has a predetermined value;

Voltage abnormality detection means for detecting an input voltage abnormality of AC power input to the input end of the power supply line;

Control means for controlling the power supply switch and the parallel converter according to the detection result of the voltage abnormality detection means,

The control unit controls the power supply switch so that a thyristor that flows a current having the same polarity as the input voltage to the input terminal is ignited when the voltage abnormality detection unit does not detect an abnormality. Controlling the converter to adjust the current flowing through the parallel converter so that the energy of the power storage means becomes a specified value and the input power factor of the AC power input to the input terminal becomes 1;

When an abnormality is detected by the voltage abnormality detection means, the power supply switch is cut off and controlled, and the parallel comparator is controlled so as to output AC power of a predetermined voltage to the power supply line using the power storage means as an energy source. An uninterruptible power supply device.

2. A power supply switch inserted in the power supply line,

Power storage means connected to the parallel converter,

A series transformer connected in series between a connection point of the power supply line with the parallel converter and the output terminal;

A series member connected to the series transformer and adjusting the AC output voltage using the power storage means as an energy source such that the AC output voltage at the output terminal has a predetermined value;

A connection point of the power supply line with the parallel converter and an input reactor interposed between the power supply switches;

Control means for controlling the power supply switch and the parallel converter in accordance with the detection result of the voltage abnormality detection means,

When the voltage abnormality detecting means does not detect an abnormality, the control means controls conduction of the power supply switch and controls the parallel converter to flow through the input reactor so that the energy of the power storage means becomes a specified value. Adjust the current,

When an abnormality is detected by the voltage abnormality detection means, the power supply switch is cut off and controlled, and the parallel converter is controlled so as to output AC power of a predetermined voltage to the power supply line using the power storage means as an energy source. Feature

3. A feed switch composed of two thyristors inserted in the feed line and connected in anti-parallel;

Power storage means connected to the parallel computer,

A series inverter connected to the series transformer and adjusting the output voltage using the power storage means as an energy source so that the AC output voltage at the output terminal becomes a predetermined value;

An input reactor interposed between a connection point of the power supply line with the parallel converter and the power supply switch;

Control means for controlling the power supply switch and the parallel converter in accordance with a detection result of the voltage abnormality detection means,

The control means controls the power supply switch so that a thyristor for supplying a current having the same polarity as the input voltage to the input terminal is ignited when the voltage abnormality detection means does not detect an abnormality. Controlling the converter to adjust the current flowing through the input reactor so that the energy of the power storage means becomes a specified value and the current flowing through the input reactor has a power factor of 1;

When an abnormality is detected by the voltage abnormality detection means, the power supply switch is cut off and controlled, and the parallel converter is controlled so as to output AC power of a predetermined voltage to the power supply line using the power storage means as an energy source. Features uninterruptible power supply.