JP2005278304A - Power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a size and a cost of an AC uninterruptible power supply with an electrolytic capacitor and a rechargeable battery. <P>SOLUTION: A load 14 and a bidirectional power converter 4 are connected to an AC input terminal 1 through an AC switch 2. The electrolytic capacitor 17b and the rechargeable battery 18 are connected to a DC line 16 of the bidirectional power converter 4. The bidirectional power converter 4 has a constitution for improving a waveform. The AC switch 2 is used for an ON/OFF control, and also used for a current limitation during initial charging of the electrolytic capacitor 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply apparatus such as an AC uninterruptible power supply apparatus including a capacitor or a storage battery.

  A conventional typical AC uninterruptible power supply includes, for example, an AC switch connected between a commercial AC power supply terminal and a load as disclosed in Patent Document 1 described later, and a commercial AC power supply via the AC switch. Detects abnormalities in the voltage of the bidirectional power converter connected to the terminal and connected to the load without going through the AC switch, the storage battery connected to the DC terminal of the bidirectional power converter, and the commercial AC power supply terminal And a power supply abnormality detection device that controls the AC switch to be turned off.

  By the way, in general, an electrolytic capacitor is connected to the DC terminal of the bidirectional power transformer. The electrolytic capacitor has a smaller capacity than the storage battery and has a faster response speed than the storage battery, and contributes to voltage stabilization.

  The AC uninterruptible power supply as described above is required to be reduced in size and cost. When the bidirectional power converter is connected to the AC power source via the AC switch while the electrolytic capacitor or the storage battery is not charged, an inrush current of the electrolytic capacitor or the storage battery flows. A method for preventing this inrush current is described in Patent Document 2 described later. In the method of Patent Document 2, the current during initial charging is limited by phase-controlling a protective thyristor for disconnecting the bidirectional power converter connected to the AC input side of the bidirectional power converter.

  However, in the method disclosed in Patent Document 2, the power supply device is inevitably large in size and high in cost because a protective thyristor is provided in addition to the AC switch between the AC input terminal and the load.

As another method for limiting the initial charging current, a method of selectively connecting a resistor to the AC input line of the bidirectional power converter is known. However, in this method, a resistor and this selective connection means are required, and the power supply apparatus becomes large and expensive.
JP 2000-341881 A JP 2000-152519 A

  The problem to be solved by the present invention is that it is difficult to easily limit the initial charging current in a power supply device having a capacitor, a storage battery, or both.

  The present invention for solving the above problems is connected between an AC input terminal for connecting an AC power source, an AC output terminal for connecting a load, the AC input terminal and the AC output terminal, and An AC switch having a current control function, an AC terminal and a DC terminal, and the AC terminal is connected to the AC input terminal via the AC switch and not via the AC switch. Bidirectional power converter connected to AC output terminal, chargeable / dischargeable power storage means connected to DC terminal of the bidirectional power converter, and power supply supplied from the AC input terminal to the AC output terminal An abnormality detection circuit for detecting whether or not the voltage is abnormal and controlling the AC switch to an OFF state when the abnormality is detected, and a charging current of the power storage means during an initial charging period of the power storage means His or limit to form a signal for executing in the AC switch, be those related to the power supply device according to claim that a switch control circuit for supplying the signal to the AC switch.

According to a second aspect of the present invention, the switch control circuit includes a current detection unit for detecting a current supplied from the AC input terminal to the power storage unit via the AC switch and a bidirectional power converter. Forming a reference value generating means for generating a reference value indicating a desired current value at the time of initial charging of the power storage means, and a control signal for bringing the output of the current detecting means close to the reference value, It is desirable to have control signal forming means for controlling the AC switch.
Further, according to a third aspect of the present invention, the converter further comprises a converter control circuit for the bidirectional power converter to perform waveform improvement control of the current flowing through the AC switch, and the current detection means includes the AC switch. The converter control circuit includes a reference wave generating means for generating a reference wave indicating a sine wave, and a waveform for causing the output of the current detecting means to follow the reference wave. It is desirable to have waveform improvement control signal forming means for forming an improvement control signal and controlling the bidirectional power converter by this control signal.
According to a fourth aspect of the present invention, the AC switch includes a switch capable of controlling a conduction angle, and the switch control circuit supplies a current smaller than a rated current of the AC switch through the AC switch during the initial charging period. It is desirable to form a control signal having a semi-fixed or fixed conduction angle and supply the control signal to the AC switch.
Further, according to a fifth aspect of the present invention, the AC switch includes a switch capable of controlling a conduction angle, and the switch control circuit is connected to the power storage unit from the AC input terminal via the AC switch and a bidirectional power converter. A current detection means for detecting a supplied current, a reference value generation means for generating a reference value indicating a desired current value at the time of initial charging of the power storage means, an output of the current detection means, and the reference value A feedback control signal forming means for forming a feedback control signal indicating a difference; a sawtooth generator for generating a sawtooth wave in synchronization with an AC voltage at the AC input terminal; and the feedback control signal and the sawtooth wave are compared. And comparing means for determining a conduction start time of the AC switch.
The switch control circuit may further include an initial charge period signal forming circuit for forming a signal indicating an initial charge period, and the comparison in response to an output of the initial charge period signal forming circuit. It is desirable to have switching means for selectively supplying the output of the means and the output of the abnormality detection circuit to the control terminal of the AC switch.
Moreover, as shown in claim 7, further comprising an output switch connected between an interconnection point of the AC switch and the bidirectional power converter and the AC output terminal, the output switch It is desirable that the off-control is performed during the initial charging period, and the on-control is performed after the initial charging period ends.
In addition, as shown in claim 8, further comprising a bypass switch connected in parallel to a series circuit of the AC switch and the output switch, the bypass switch being turned on during an off period of the output switch It is desirable that

According to the invention of each claim, since the AC switch for shutting off the power supply when the power supply is abnormal is also used for controlling the initial charging of the capacitor, the storage battery, or both, the power supply device can be reduced in size and Cost reduction can be achieved.
Further, according to the invention of claim 2, when the current detecting means is provided, the initial charging current can be controlled to a desired value, and the initial charging can be satisfactorily achieved.
According to the invention of claim 3, since the current detecting means is used for both the initial charging control and the waveform improvement control, it is possible to further reduce the size and cost.
Further, in the invention of claim 4, since the control signal in which the conduction angle of the AC switch is semi-fixed or fixed is formed, the configuration of the control circuit of the AC switch can be simplified.
According to the invention of claim 5, the conduction angle control of the AC switch can be easily achieved.
In addition, according to the invention of claim 6, it is possible to easily achieve the initial charge control and the cutoff control at the time of abnormality.
Further, according to the invention of claim 7, during the initial charging, the power supply from the AC switch to the load side is prohibited by the output switch, and the initial charging can be achieved quickly and satisfactorily.
According to the eighth aspect of the present invention, it is possible to supply power to the load via the bypass switch even during the initial charging period using the AC switch.

  Next, an embodiment of the present invention will be described with reference to FIGS.

  An AC uninterruptible power supply device as a power supply device according to Embodiment 1 of the present invention shown in FIG. 1 includes an AC input terminal 1 connected to, for example, a 200 V three-phase commercial AC power source, a three-phase AC switch 2, and the like. AC output terminal 3, three-phase bidirectional power converter 4, power storage means 5, input switch 6, output switch 7, bypass switch 8, abnormality detection circuit 9, switch control circuit 10, A converter control circuit 11 and a current detector 12 are provided. In addition, in FIG. 1 of the block display, all AC portions are configured in three phases. Therefore, the AC switch 2 is also connected to each phase line, and the current detector 12 is also connected to each phase line.

  The AC switch 2 is connected between the AC input terminal 1, the AC output terminal 3, and the bidirectional power converter 4. More specifically, the input terminal of the AC switch 2 is connected to the AC input terminal 1 via, for example, an input switch 6 having a mechanical switch structure, and the output terminal of the AC switch 2 is connected to, for example, an output switch 7 having a mechanical switch structure. Are connected to the AC output terminal 3. The AC switch 2 is preferably formed of a current-controllable semiconductor switch. In FIG. 1, the AC switch 2 includes antiparallel connection circuits of first and second thyristors S1 and S2, and is connected in series to the power supply line. The AC switch 2 can also be configured by another semiconductor switch such as an IGBT, a transistor, or an FET, a combination of a semiconductor switch and a mechanical switch, or a combination of a plurality of different semiconductor switches.

  The output switch 7 is connected between the interconnection point 13 between the AC switch 2 and the bidirectional power converter 4 and the AC output terminal 3. The bypass switch 8 is connected in parallel to the series circuit of the input switch 6, the AC switch 2, and the output switch 7. The bypass switch 8 is ON-controlled while the output switch 7 is OFF, and the power supplied from the AC input terminal 1 is AC. A load 14 is supplied via the output terminal 3.

  The bidirectional power converter 4 has a power factor improvement function and a harmonic current suppression function as an AC power supply current waveform improvement function, and a function of charging the power storage means 5 to perform AC-DC conversion, And a function of performing DC-AC conversion in the event of a power failure. The AC terminal of the bidirectional power converter 4 is connected to the AC switch 2 via an AC line 15. Details of the bidirectional power converter 4 will be described later.

  The power storage means 5 can also be called a power storage device, and is composed of a capacitor, a storage battery, both of these, or the like. In FIG. 1, the power storage means 5 includes an electrolytic capacitor 17, a storage battery 18, and a switch 19. The electrolytic capacitor 17 has a capacity smaller than that of the storage battery 18 and has a faster response, that is, a charge / discharge speed, than the storage battery 18. Instead of the electrolytic capacitor 17, another type of capacitor or an accumulator such as an electric double layer may be used. The electrolytic capacitor 17 is directly connected to the bidirectional power converter 4, and the storage battery 18 is connected to the bidirectional power converter 4 via a switch 19.

  The abnormality detection circuit 9 is connected to the AC input terminal 1 via the input switch 6 and detects an AC power supply voltage drop and an overvoltage abnormality. When this is detected, the AC switch 2 is turned off and bidirectional power conversion is performed. The device 4 is inverter-controlled. The abnormality detection circuit 9 compares the AC power supply voltage and the reference voltage with a comparator to detect a drop or overvoltage in the AC power supply voltage, and turns on the AC switch 2 when it is normal and controls it off when it is abnormal. It is. The abnormality detection circuit 9 is connected to the switch control circuit 10 by a line 20 and is connected to the converter control circuit 11 by a line 21.

  The current detector 12 is a current transformer or magnetoelectric transducer arranged so as to detect the current of the AC line 15 ′ of the AC switch 2, and sends this detection signal to the switch control circuit 10 through the line 22 and through the line 23. This is sent to the converter control circuit 11.

  The switch control circuit 10 has a function of sending a control signal for charge control to the control terminals of the thyristors S1 and S2 via the lines 24 and 25 during the initial charge period of the power storage means 5, and a first function when normal after completion of the initial charge. The second thyristor S1 and the second thyristor S2 are continuously turned on, and when the abnormality is detected by the abnormality detection circuit 9, the output switch 7 is turned off and the bypass switch 8 is turned on during the initial charging period. And a function to control. Details of the switch control circuit 10 will be described later.

  The converter control circuit 11 operates the bidirectional power converter 4 as an AC-DC converter, that is, a converter having a waveform improvement function when the initial charging period and the output of the abnormality detection circuit 9 are normal and not abnormal. When the output of the abnormality detection circuit 9 indicates abnormality, the bidirectional power converter 4 is operated as a DC-AC converter, that is, an inverter. The output line of the converter control circuit 11, that is, the control signal transmission line 26 is connected to the bidirectional power converter 4. Lines 27 and 28 connect the AC line 15 and DC line 16 of the bidirectional power converter 4 to the converter control circuit 11. Details of the converter control circuit 11 will be described later.

  As shown in detail in FIG. 2, the bidirectional power converter 4 of FIG. 1 includes a switch circuit 30, first, second and third inductors L 1, L 2, L 3 and a high frequency component removing filter 34. The first, second and third AC terminals 15a, 15b and 15c in FIG. 2 are connected to the AC line 15 in FIG. 1, and the first and second DC terminals 16a and 16b are connected to the DC line 16 in FIG. Is done. The electrolytic capacitor 17 and the storage battery 18 in FIG. 1 are connected between the first and second DC terminals 16a and 16b in FIG.

  The switch circuit 30 includes first, second, third, fourth, fifth and sixth diodes D1, D2, D3, D4, D5, D6 and first to sixth diodes connected in a three-phase bridge. First, second, third, fourth, fifth and sixth switches Q1, Q2, Q3, Q4, Q5 and Q6 as conversion switches connected in reverse parallel to D1 to D6, respectively Consists of. Although the first to sixth switches Q1 to Q6 are shown as insulated gate bipolar transistors or IGBTs in FIG. 2, they can be replaced by other controllable semiconductor switches such as FETs and transistors.

Control terminals (gates) of the first to sixth switches Q1 to Q6 are connected to the converter control circuit 11 of FIG. Interconnection point 31 of first and second diodes D1, D2 of switch circuit 30, interconnection point 32 of third and fourth diodes D3, D4, and interconnection point of fifth and sixth diodes D5, D6 33 is connected to the first, second and third AC lines 15a, 15b and 15c through first, second and third inductors L1, L2 and L3, respectively. The cathodes of the first, third and fifth diodes D1, D3 and D5 are connected to the first DC line 16a, and the anodes of the second, fourth and sixth diodes D2, D4 and D6 are the second DC. It is connected to the line 16b.
The high-frequency component removing filter 34 includes capacitors C1, C2, and C3, and removes high-frequency components based on on / off of the first to sixth switches Q1 to Q6 at high frequencies (for example, 20 to 100 kHz). First, second and third inductors L1, L2, connected between the first, second and third AC terminals 15a, 15b, 15c and the interconnection points 31, 32, 33 of the switch circuit 30, L3 functions as a power factor improving reactor and a step-up reactor during AC-DC conversion, that is, AC-DC conversion operation, and high frequency components during DC-AC (DC-AC) conversion, that is, DC-AC conversion (inverter) operation. Functions as a removal reactor.

  As shown in detail in FIG. 3, the switch control circuit 10 in FIG. 1 includes a current detection circuit 35 as a part of current detection means, a reference voltage source 36 as reference value generation means, and an error as feedback control signal formation means. It comprises an amplifier 37, a sawtooth generator 38, a comparator 39, a switching means 40, a drive circuit 41, and an initial charge period signal forming circuit 42.

  A current detection circuit 35, which constitutes a current detection means with the current detector 12 of FIG. 1, is for obtaining a DC current detection signal corresponding to the output of the current detector 12 on the line 22, and is a rectifier. And a smoothing circuit.

  The error amplifier 37 has one input terminal connected to the current detection circuit 35 and the other input terminal connected to the reference voltage source 36, and a reference voltage indicating a current detection signal and a desired current value at the time of initial charging. A signal indicating the difference between the two is output as a feedback control signal Vf.

  The sawtooth generator 38 is connected to the AC input terminal 1 via the line 29 and the input switch 6 shown in FIG. 1, and responds to the zero crossing points t0 and t2 of the AC power source voltage Vin shown in FIG. Then, the sawtooth voltage Vtac shown in FIG. 7B is repeatedly generated.

  One input terminal of the comparator 39 is connected to the error amplifier 37, and the other input terminal is connected to the sawtooth generator 38. Therefore, the comparator 39 compares the current feedback control signal Vf with the sawtooth voltage Vtac as shown in FIG. 7B, and generates a binary output shown in FIG. 7C. The pulses from t1 to t2 and t3 to t4 in FIG. 7C or the trigger pulses synchronized with t1 and t3 in FIG. Used as.

  The switching means 40 has first and second contacts a, b, and outputs the output of the comparator 39 during the period when the first contact a is on via the drive circuit 41 to the gates of the thyristors S1, S2 in FIG. The output of the abnormality detection circuit 9 on the line 20 is sent to the gates of the thyristors S1 and S2 while the contact b is on.

  Switching of the switching means 40 is executed by the output of the initial charging period signal forming circuit 42. The initial charging period signal forming circuit 42 is connected to the line 29, and when the input switch 6 is turned on while the power supply voltage is supplied to the AC input terminal 1 of FIG. 1, or the input switch 6 is turned on. It comprises a timer that generates a pulse having a time width Tc as an initial charging period signal in synchronism with the supply of power supply voltage to the AC input terminal 1 in the state. The contact a of the switching means 40 is turned on when a pulse having a predetermined time width Tc is generated from the initial charging period signal generation circuit 42, and then turned off. The contact point b of the switching means 40 operates in the opposite direction to the contact point a. In this embodiment, the predetermined time width Tc is determined to be constant so as to coincide with the initial charge required time of the power storage means 5, but a means for adjusting the predetermined time width Tc is provided, or the voltage of the power storage means 5 or The charging current is detected to determine the end point of the initial charging, and the end point of the predetermined time width Tc can be determined based on this determination.

  The output terminal of the initial charging period signal forming circuit 42 is also connected to the control terminals of the output switch 7 and the bypass switch 8 of FIG. Accordingly, the output switch 7 is turned off in synchronization with the pulse having the predetermined time width Tc, and the bypass switch 8 is turned on. When the pulse having the predetermined time width Tc disappears, the output switch 7 is turned on, and conversely, the bypass switch 8 is turned off.

FIG. 4 schematically shows the inside of the converter control circuit 11 of FIG. As apparent from FIG. 4, the converter control circuit 11 has an AC-DC conversion control circuit 44, a DC-AC conversion control circuit 45, and a switching means 46.
The AC-DC conversion control circuit 44 forms control signals for the first to sixth switches Q1 to Q6 for executing AC-DC conversion, and the DC-AC conversion control circuit 45 executes DC-AC conversion. The control signals for the first to sixth switches Q1 to Q6 are formed. The switching means 46 sends the signal of the output line 26a of the AC-DC conversion control circuit 44 to the output line 26 when the power supply abnormality detection signal of the line 21 indicates normal, and when the power supply abnormality detection signal indicates abnormality. The signal on the output line 26 b of the DC-AC conversion control circuit 45 is sent to the line 26. The line 26 in FIG. 4 is connected to the gates of the first to sixth switches Q1 to Q6 in FIG. Note that the lines 26a, 26b, and 26 in FIG. 4 indicate six lines.

  Next, details of the AC-DC conversion control circuit 44 of FIG. 4 will be described with reference to FIGS. The AC-DC conversion control circuit 44 in FIG. 5 includes first, second and third phase voltage detection circuits 52a, 52b and 52c, first, second and third multipliers 53a, 53b and 53c, 1, first and second subtracters 54a, 54b and 54c, first, second and third comparators 55a, 55b and 55c, first, second and third inverted signal forming circuits 56a, 56 b and 56 c, a sawtooth generator 57, two voltage detection resistors 58 and 59, a reference voltage source 60, and an error amplifier 61.

  The first, second and third phase voltage detection circuits 52a, 52b and 52c are connected to the three-phase voltage detection line 27 and correspond to the first, second and third phase voltages of the AC line 15. Sinusoidal voltages Va, Vb and Vc are output. Note that the first, second, and third phase voltage detection circuits 52a, 52b, and 52c of FIG. 5 can be collectively configured as a three-phase voltage detection circuit.

  The two voltage detection resistors 58 and 59 are connected to the DC line 16 in FIG. 1 via the line 28, and apply a voltage division value of the voltage of the DC line 16 to one input terminal of the error amplifier 61. The error amplifier 61 outputs a signal indicating the difference between the reference voltage of the reference voltage source 60 and the voltage detected by the voltage detection resistors 58 and 59 as a DC output voltage command value Vd.

The first, second and third multipliers 53a, 53b and 53c are first, second and third phase reference sine signals obtained from the first, second and third phase voltage detection circuits 52a, 52b and 52c. The waves Va, Vb and Vc are multiplied by the output voltage command value Vd of the error amplifier 61 to produce first, second and third phase command values Va′Vb ′ and Vc ′. The first, second and third phase command values Va'Vb 'and Vc' correspond to the amplitudes of the first, second and third phase reference sine waves Va, Vb and Vc modulated by the output voltage command value Vd. To do. A divider can be provided in place of the multipliers 53a, 53b, 53c.
The first, second and third subtracters 54a, 54b and 54c are the difference between the first, second and third phase command values Va ', Vb' and Vc 'and the three-phase current detection signal of the line 23. Are output as first, second and third phase switch control signals V1, V2 and V3 shown in FIG.
The sawtooth generator 57 can also be called a carrier generator, and is schematically shown in FIG. 8A at a frequency of an AC voltage at the AC input terminal 1, for example, a frequency sufficiently higher than 50 Hz, for example, 20 to 100 kHz. A sawtooth voltage Vt is generated. The sawtooth wave generator 57 can be replaced with a triangular wave generator. The amplitude of the sawtooth voltage Vt is set so as to cross the first, second and third phase switch control command values V1, V2 and V3.

  The first, second and third comparators 55a, 55b and 55c are the first, second and third switch control commands obtained from the first, second and third subtracters 54a, 54b and 54c. The first, third and fifth switch controls comprising the PWM signals shown in FIGS. 8B, 8D and 8F, comparing the values V1, V2 and V3 with the sawtooth voltage Vt of the sawtooth generator 57. Signals G1, G3, G5 are formed.

The inversion signal forming circuits 56a, 56b, and 56c are connected to the first, second, and third comparators 55a, 55b, and 55c, and are shown in FIGS. 8B, 8D, and 8F. Second, fourth, and sixth switch control signals G2, G4, and G6 shown in FIGS. 8C, 8E, and 8G are formed of the five switch control signals G1, G2, and G3. The second, fourth and sixth switch control signals G2, G4 and G6 are provided with three comparators instead of the inverted signal forming circuits 56a, 56b and 56c, and the sawtooth voltage Vt is inputted to these positive input terminals. The first, second and third switch control command values V1, V2 and V3 may be inputted to the negative input terminal. It is desirable to provide a known dead time between the first, third and fifth switch control signals G1, G3, G5 and the second, fourth and sixth switch control signals G2, G4, G6. .
The first to sixth switch control signals G1 to G6 are supplied to the control terminals of the first to sixth switches Q1 to Q6 via the switching means 46 of FIG.

  FIG. 6 shows the DC-AC conversion control circuit 45 of FIG. 4 in detail. The DC-AC conversion control circuit 45 is a well-known circuit and includes first, second, and third phase circuits 71, 72, 73. The first phase circuit 71 includes a first phase reference voltage generator 74, a voltage detection circuit 75, a reference voltage source 76, in order to form control signals G1 'and G2' for the first and second switches Q1 and Q2. An error amplifier 77, a multiplier 78, a sawtooth wave generator 79, a comparator 80, and an inverted signal forming circuit 81 are included.

  The voltage detection circuit 75 is composed of a three-phase rectifying / smoothing circuit connected to the AC line 15 of FIG. A signal corresponding to the difference between the DC voltage corresponding to the first, second and third-phase AC voltages obtained from the voltage detection circuit 75 and the reference voltage of the reference voltage source 76 is formed by the error amplifier 77, and this is the voltage. This is a feedback signal. The voltage feedback signal is a direct current signal. In FIG. 6, the voltage detection circuit 75 detects the three-phase voltage, but it can be modified to detect the first-phase voltage instead. The voltage feedback signal obtained from the error amplifier 77 is also sent to the second and third phase circuits 72 and 73.

  The first phase reference voltage generator 74 generates a first phase reference voltage Va composed of a sine wave shown in FIG. The second and third phase reference voltage generators included in the second and third phase circuits 72 and 73 generate the second and third phase reference voltages Vb and Vc shown in FIG. The first, second, and third phase reference voltages Va, Vb, Vc in FIG. 9 are, for example, 50 or 60 Hz sine wave alternating voltages having a phase difference of 120 degrees in sequence, and the alternating current at the alternating current input terminal 1 in FIG. Has the same frequency as the voltage. Note that a pulsating waveform obtained by full-wave rectifying a sine wave can be transmitted from the first phase reference voltage generator 74.

  One input terminal of the multiplier 78 is connected to the first phase reference voltage generator 74, and the other input terminal is connected to the error amplifier 77. Accordingly, the multiplier 78 multiplies the first phase reference voltage Va by the voltage feedback signal to form a signal. The output signal of the multiplier 78 includes AC voltage waveform information and output voltage adjustment information. A divider can be provided in place of the multiplier 78.

  The sawtooth generator 79 is a sawtooth voltage or carrier at a repetition frequency of, for example, 20-100 kHz, which is sufficiently higher than the AC voltage of the AC line 15 and the frequencies of the first, second and third phase reference voltages Va, Vb, Vc. Generate a waveform. The sawtooth generator 79 of the first phase circuit 71 is connected to the second and third phase circuits 72, 73 to provide a synchronization signal. A triangular generator can be provided in place of the sawtooth generator 79. Further, either the sawtooth generator 79 of the DC-AC conversion control circuit 45 or the sawtooth generator 57 of the AC-DC conversion control circuit 44 is omitted, and the sawtooth generator 79 or the sawtooth generator 57 is replaced. The AC-DC conversion control circuit 44 and the DC-AC conversion control circuit 45 can be shared.

  One or negative input terminal of the comparator 80 is connected to the multiplier 78, and the other or positive input terminal is connected to the sawtooth generator 79. Therefore, the comparator 80 compares the sawtooth voltage with the output signal of the multiplier 78, and outputs a first control signal G1 'for DC-AC conversion comprising a known PWN signal.

  An inversion signal forming circuit 81 connected to the comparator 80 forms a second control signal G2 'composed of a phase inversion signal of the first control signal G1'. A comparator is provided in place of the inversion signal forming circuit 81, the output signal of the multiplier 78 is input to the positive input terminal, and the sawtooth voltage is input to the negative input terminal, so that the second control signal G2 comprising the PWM signal is input. 'Can be formed. It is desirable to provide means for adding a known dead time between the first and second control signals G1 'and G2'.

The second phase circuit 72 and the third phase circuit 73 are formed in the same manner as the first phase circuit 71, and the third to sixth control signals G3 'to G6 for the third to sixth switches Q3 to Q6. ′ Is sent out.
The first to sixth control signals G1 'to G6' of FIG. 6 for driving the switch circuit 30 of FIG. 2 by DC-AC driving, that is, inverter driving, are connected to the first to sixth switches via the switching means 46 of FIG. It is sent to the control terminals of Q1 to Q6.

  The operation of the AC uninterruptible power supply shown in FIG. 1 will be described. When an AC voltage is supplied to the AC input terminal 1 and the input switch 6 is turned on at the start of power supply to the load 14, that is, when the electrolytic capacitor 17 and the storage battery 18 are uncharged or incompletely charged, the switch control circuit 10 3, a pulse having a predetermined time width Tc is generated from the initial charging period signal forming circuit 42 of FIG. 3, the contact a of the switching means 40 is turned on, and the output of the comparator 39 is the thyristors S1, S2 of FIG. The current supplied to the power storage means 5 via the bidirectional power converter 4 is limited to a predetermined value, and an excessive inrush current does not flow through the electrolytic capacitor 17. In this embodiment, since the output switch 7 is controlled to be off during the initial charging period and the bypass switch 8 is controlled to be on, power is supplied to the load 14 via the bypass switch 8 even during the initial charging period. The

  When the initial charging period ends, the abnormality detection circuit 9 is connected to the gates of thyristors S1 and S2. Since the abnormality detection circuit 9 generates a signal for always turning on the thyristors S1 and S2 in the normal state, it is possible to supply power to the load 14 via the AC switch 2. Since the output switch 7 is turned on and the bypass switch 8 is turned off after the completion of the initial charging, power is supplied to the load 14 through the AC switch 2 and the output switch 7. In addition, after the initial charging period ends, the bidirectional power converter 4 performs an AC-DC conversion operation to charge the power storage unit 5 after the initial charging.

  When the abnormality detection circuit 9 detects an abnormality such as a power failure, the AC switch 2 is turned off, the bidirectional power converter 4 is switched to the DC-AC conversion operation, and the DC voltage of the storage means 5 is converted into an AC voltage. To the load 14. At this time, since the AC switch 2 is in the OFF state, the energy of the power storage means 5 is not consumed on the AC input terminal 1 side.

This embodiment has the following effects.
(1) Since the AC switch 2 is used not only for shutting down when an abnormality occurs but also for controlling the initial charging of the power storage means 5, a special resistor or control element for limiting the current during the initial charging is provided. Can be reduced, and the AC uninterruptible power supply can be reduced in size and cost. Further, the efficiency can be increased by the amount corresponding to the power loss caused by the resistance or the control element of the conventional device.
(2) Since the output of the current detector 12 is used by both the switch control circuit 10 and the converter control circuit 11, the control means can be reduced in size and cost.
(3) Since the output switch 7 and the bypass switch 8 are provided, power can be supplied to the load 14 even during the initial charging period.
(4) Since the initial charge period signal forming circuit 42 is provided, the initial charge can be automatically performed.
(5) Since the initial charging current is feedback controlled, the initial charging can be favorably advanced while maintaining the initial charging current at a constant value or a desired value.
(6) Since the input switch 6, the output switch 7 and the bypass switch 8 are provided, the bypass switch 8 is turned on and the input switch 6 and the output switch 7 are turned off by an operating means not shown in the figure, so that the bidirectional power converter 4 or the storage means 5 can be easily maintained.

  FIG. 10 shows a part of the power supply apparatus according to the second embodiment. The power supply apparatus of the second embodiment is the same as the first embodiment except that the initial charging period signal forming circuit 42 of FIG. 3 is modified to an initial charging period signal forming circuit 42a shown in FIG.

  The initial charging period signal forming circuit 42a shown in FIG. 10 includes a trigger circuit 81, an RS flip-flop 82 as a pulse forming means, a voltage detection circuit 83, a comparator 84, and a reference voltage source 85. The trigger circuit 81 generates a trigger signal in synchronization with the power supply from the AC input terminal 1 of FIG. 1 and sends it to the set terminal S of the RS flip-flop 82. As a result, the output terminal Q of the RS flip-flop 82 becomes high level, and generation of a pulse having a predetermined time width Tc is started. The voltage detection circuit 83 forms a voltage detection signal indicating the voltage of the electrolytic capacitor 17. The comparator 84 compares the voltage detection signal with the reference voltage of the reference voltage source 85, and gives a reset trigger signal to the reset terminal R of the RS flip-flop 82 when the voltage detection signal becomes higher than the reference voltage. As a result, the pulse having the predetermined time width Tc ends.

  The second embodiment has the same effect as the first embodiment and also has the effect that the end point of the time width Tc can be reasonably determined.

The present invention is not limited to the above-described embodiments, and for example, the following modifications are possible.
(1) One phase portion of the AC switch 2 can be modified as shown in FIG. The AC switch 2a shown in FIG. 11 (A) is composed of reverse parallel circuits of IGBTs (insulated gate type bi-hollar transistors) S1 ′ and S2 ′, and reverse current blocking diodes Da and Db are connected in series to the IGBTs S1 ′ and S2 ′. It is connected.
The AC switch 2b shown in FIG. 11 (B) is configured by a semiconductor switch including four diodes Da, Db, Dc, and Dd that are bridge-connected and one thyristor S.
The AC switch 2c shown in FIG. 11C is configured by a triac S ′ capable of bidirectional control.
The AC switch 2 shown in FIG. 1 is not limited to that shown in FIGS. 1 and 11 and may be any switch as long as the AC voltage can be turned on / off at high speed.
(2) The bidirectional power converter 4 is not limited to the circuit of FIG. 2 and may be any one as long as both AC-DC conversion and DC-AC conversion are possible. Further, as shown in FIG. 8, the first to sixth switches Q1 to Q6 are not turned on / off at a high frequency in the entire period of one cycle of the sine wave of the input voltage, but are turned on / off only in a specified period. Can be deformed.
(3) A part or all of the switch control circuit 10 and the converter control circuit 1 may be constituted by a digital arithmetic means such as a microcomputer or a DSP (digital signal processor).
(4) The AC power supply, the bidirectional power converter 4 and the load 14 can be single phase.
(5) An initial charging start command can be given based on a manually operated switch.
(6) The input terminal of the abnormality detection circuit 9 can be connected to the output terminal of the AC switch 2.
(7) In the preferred embodiment shown in FIG. 1, the current detector 12 for the bidirectional power converter 4 is shared by the switch control circuit 10 for initial charging. Instead, the input side of the AC switch 2 is used instead. Alternatively, another current detector can be arranged on the AC line 15 of the bidirectional power converter 4 and used for the initial charge control. Further, the waveform improvement by the bidirectional power converter 4 can be performed by a combination of the current detector 12 on the line 15 ′ in FIG. 1 and another current detector (not shown) provided on the line 15.
(8) When current feedback control during initial charging is not required, the on-time width of the AC switch 2 during initial charging, that is, the conduction angle, can be fixed or semi-fixed. That is, the predetermined time width Tc can be set to be semi-fixed so as to be constant or adjustable without making it variable.
(9) The AC switch 2 can be controlled by a variable resistance such as a transistor or FET, and the resistance value of the AC switch 2 can be controlled or kept constant during initial charging.
(10) One, a plurality, or all of the input switch 6, the output switch 7, and the bypass switch 8 of FIG.
(11) The voltage supplied to the load 14 at the start of power supply from the AC switch 2 to the load 14 can be gradually increased by phase control of the AC switch 2.
(12) The switching means 40 can be composed of a semiconductor switch.

The present invention is applicable to a power supply device such as an AC uninterruptible power supply.

It is a block diagram which shows the alternating current uninterruptible power supply of Example 1 of this invention. It is a circuit diagram which shows the bidirectional | two-way power converter of FIG. 1 in detail. FIG. 2 is a block diagram illustrating a switch control circuit in FIG. 1. It is a block diagram which shows in detail the converter control circuit of FIG. FIG. 5 is a circuit diagram showing in detail the AC-DC conversion control circuit of FIG. 4. FIG. 5 is a circuit diagram showing in detail the DC-AC conversion control circuit of FIG. 4. FIG. 4 is a waveform diagram showing the state of each part of the switch control circuit of FIG. 3. It is a wave form diagram which shows the state of each part of FIG. It is a wave form diagram which shows the reference voltage of the 1st-3rd phase of FIG. It is a circuit diagram which shows a part of electric power supply apparatus of Example 2. FIG. It is a circuit diagram which shows the alternating current switch of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC input terminal 2 AC switch 3 AC output terminal 4 Bidirectional power converter 5 Power storage means 9 Abnormality detection circuit 10 Switch control circuit 11 Converter control circuit 17 Electrolytic capacitor

Claims (8)

AC input terminal for connecting AC power supply,
AC output terminal for connecting the load,
An AC switch connected between the AC input terminal and the AC output terminal and having a current control function;
Bidirectional power conversion comprising an AC terminal and a DC terminal, wherein the AC terminal is connected to the AC input terminal via the AC switch and connected to the AC output terminal without passing through the AC switch And
Charge / discharge power storage means connected to the DC terminal of the bidirectional power converter;
An abnormality detection circuit for detecting whether or not a power supply voltage supplied from the AC input terminal to the AC output terminal is abnormal, and controlling the AC switch in an OFF state when the abnormality is detected;
A switch control circuit that forms a signal for controlling or limiting the charging current of the power storage means in the initial charging period of the power storage means by the AC switch and supplies the signal to the AC switch. A power supply device characterized by the above. The switch control circuit includes:
Current detection means for detecting current supplied from the AC input terminal to the power storage means via the AC switch and bidirectional power converter;
Reference value generating means for generating a reference value indicating a desired current value at the time of initial charge of the power storage means;
The control signal forming means for forming a control signal for bringing the output of the current detection means close to the reference value and controlling the AC switch by the control signal. Power supply device. Furthermore, the converter control circuit for the bidirectional power converter to perform the waveform improvement control of the current flowing through the AC switch,
The current detection means detects a current flowing through the AC switch;
The converter control circuit forms a reference wave generating means for generating a reference wave indicating a sine wave, and a waveform improvement control signal for causing the output of the current detecting means to follow the reference wave. 3. The power supply apparatus according to claim 2, further comprising a waveform improvement control signal forming means for controlling the bidirectional power converter. The AC switch comprises a switch capable of controlling the conduction angle,
The switch control circuit forms a control signal having a semi-fixed conduction angle for supplying a current smaller than a rated current of the AC switch through the AC switch during the initial charging period, and the control signal is supplied to the AC switch. The power supply device according to claim 1, wherein the power supply device is supplied to the power supply. The AC switch comprises a switch capable of controlling the conduction angle,
The switch control circuit includes:
Current detection means for detecting current supplied from the AC input terminal to the power storage means via the AC switch and bidirectional power converter;
Reference value generating means for generating a reference value indicating a desired current value at the time of initial charge of the power storage means;
Feedback control signal forming means for forming a feedback control signal indicating a difference between the output of the current detection means and the reference value;
A sawtooth generator that generates a sawtooth wave in synchronization with the AC voltage of the AC input terminal;
4. The power supply apparatus according to claim 1, further comprising a comparison unit that compares the feedback control signal and the sawtooth wave to determine a conduction start time of the AC switch. The switch control circuit further includes an initial charging period signal forming circuit for forming a signal indicating an initial charging period;
And switching means for selectively supplying the output of the comparison means and the output of the abnormality detection circuit to the control terminal of the AC switch in response to the output of the initial charge period signal forming circuit. The power supply device according to claim 5.   And an output switch connected between an interconnection point between the AC switch and the bidirectional power converter and the AC output terminal, and the output switch is controlled to be off during the initial charging period. The power supply device according to claim 1, wherein the power supply device is on-controlled after the end of the charging period.   8. The apparatus according to claim 7, further comprising a bypass switch connected in parallel to a series circuit of the AC switch and the output switch, wherein the bypass switch is ON-controlled during an OFF period of the output switch. The power supply device described.

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