JPS6218980A - Standby type no-break power source - Google Patents

Abstract

PURPOSE:To reduce the size of a power source and to save energy by utilizing an inverter for the removal of harmonic waves of a load current and for the charge of a storage battery during commercial power receiving to effectively use the inverter. CONSTITUTION:The harmonic wave components in a current of a load 17 are detected by a harmonic wave detector 23. A controller 22 of an inverter 15 is controlled by the detected harmonic wave component of the detector 23 during the receiving of commercial power. The inverter 15 is also used as a charger of a storage battery 14. Thus,the variations in the battery voltage and current of the battery 14 are detected by a battery variation detector 24, and the battery variation component and the detected component of the detector 13 are combined by a composite circuit 25. The combined output and the inverter variation component of an inverter variation detector 21 are switched by a switching circuit 26, and supplied to the controller 22. The circuit 26 is controlled by as a power interruption detector 19.

Description

Detailed Description of the Invention "Industrial Application Field" This invention is used, for example, as a power supply for a small computer, and when the commercial power supply is normal, the commercial power supply is directly transmitted to the load, and when the commercial power supply is out of service, the DC power of the storage battery is reduced. This invention relates to a standby uninterruptible power supply that converts output into alternating current using an inverter and supplies it to a load.

"Prior Art" Generally, the floating charging method shown in FIG. 12 has been widely used as a small uninterruptible power supply because of its simple configuration.

AC power from the commercial power supply 11 is supplied to the charger 13 through the input terminal 12 to generate DC power, and the DC power is supplied to the storage battery 14 for charging, and also to the inverter 15, which converts it into AC power. The AC power was converted into AC power and supplied to the load 17 through the output terminal 16. However, in this conventional device, while receiving commercial power, the charger 13 must supply the sum of the input power to the inverter 15 and the charging power to the storage battery 14;
3 is difficult to downsize, and the output power output to the output terminal 16 when receiving commercial power is supplied through the two converters, the charger 13 and the inverter 15.
There was a problem that the power loss in these two converters was large, and the input power was correspondingly large.

As a countermeasure to this problem, standby type uninterruptible power supplies with high-speed switching circuits aimed at energy conservation and miniaturization have been adopted. Most commercial equipment including small computers can be installed with this standby system at a distance of 10m! This is based on the fact that even in the case of instantaneous power outages below +, operation can continue without any adverse effects. That is, as shown in FIG. 13, while receiving commercial power, the AC power from the input terminal 12 is sent directly to the output terminal 6 through the AC switch 18 that can be switched at high speed, and the AC power from the input terminal 12 is sent through the charger 13. The storage battery 14 is charged, and the inverter 15 performs no-load operation in synchronization with commercial power. In case of momentary interruption of commercial power supply power or voltage drop, turn off the AC switch 18 and reduce the power to 1/4.
The power of the inverter 15 is switched and supplied to the output terminal 16 at approximately 5 ms cycles to enable continued operation of the load. In this standby method, the charger 13 is connected to the inverter 15.
It is only necessary to supply the no-load power of 1 and the amount for charging the storage battery 14, and the power capacity of the charger 13 is about 115 liters compared to the floating charging method, and the effects of miniaturization and energy saving are large and large.

``Problems to be solved by the invention'' Depending on the load, distortion may occur in the power supplied to it, generating intermittent harmonics, and these harmonics may flow to the commercial power line, causing devices that share this power line. may be adversely affected by its harmonics.

For this reason, in the past, filters were specifically provided to remove such harmonics. When the order of the generated harmonics differs, it is necessary to use filters with different characteristics accordingly. The purpose of the present invention is to provide a standby type uninterruptible power supply device that can charge a storage battery and remove harmonics by effectively utilizing an inverter that is in an unloaded standby mode when receiving commercial power and is normally in a state of almost no operation. It's about doing.

"Means for Solving the Problems" According to the present invention, harmonic detection means is provided, and the harmonic detection means detects harmonic components contained in the current flowing through the load. While receiving commercial power, the detected harmonic components are supplied to the control section of the inverter in place of the fluctuation detection output that suppresses fluctuations in the inverter output power, and the harmonic components are suppressed. Also, while receiving commercial power, the inverter is operated as a charger, and the commercial power is charged to the storage battery through the inverter. In this way, while receiving commercial power, the inverter is effectively used to remove harmonic components of the load current and charge the storage battery.

"Embodiment" Basic configuration FIG. 1 shows an embodiment of a standby type uninterruptible power supply according to the present invention. An input terminal 12 to which a commercial power source 11 is connected is connected to an output terminal 16 through a high-speed AC switch 18.

Storage battery 14 is connected to output terminal 16 through inverter 15 . A power outage detection circuit 19 is connected to the input terminal 12, and when the power outage detection circuit 19 detects a power outage in the commercial power supply 11, its output turns off the AC switch 18. In this state, the DC power of the storage battery 14 is converted into AC power by the inverter 15 and supplied to the output terminal 16. While this inverter 15 is converting into AC power, as has been done in the past, fluctuations in the output voltage v1n and output current "In" of the inverter 15 are detected by the imperme fluctuation detection section 21, and the inverter is 15 control unit 22
is controlled to suppress the inverter output voltage v1n and the output current ■in during overload.

In this invention, the harmonic components in the current flowing through the output terminal 16 and the current It in the load 17 are detected by the harmonic detection circuit 2.
Detected at 3. While receiving commercial power, the control section 22 of the inverter is controlled by the harmonic components detected by the harmonic detection circuit 23. The inverter 15 is also used as a charger for the storage battery 14. Therefore, in FIG. 1, fluctuations in the battery voltage vb and battery current Ib of the storage battery 14 are detected by the battery fluctuation detection section 24, and this battery fluctuation component and the harmonic components detected by the harmonic detection circuit 23 are synthesized by the combining circuit 25. be done. This combined output and the inverter fluctuation component of the inverter fluctuation detection section 21 are switched by the switching circuit 26 and supplied to the inverter control section 22 . The switching circuit 26 is controlled by a power outage detection circuit 19, and supplies the inverter fluctuation component to the control unit 22 during a power outage, and supplies the output of the combining circuit 25 to the inverter control unit 22 while receiving commercial power.

Specific Configuration Next, a specific example of the device of the present invention will be explained. FIG. 2 shows an example of how the switching circuit 31 of the inverter 15, the storage battery 14, and the AC switch 18 are connected. Input terminal 12 ap
One side 12m of 12b is an output terminal 16a through an AC switch 18 which is a semiconductor switch element.

16b is connected to one side 16m, and the other input terminal 12b
and output terminal 16b are directly connected to each other.

The switching circuit 31 of the inverter 15 may be configured as a transistor bridge, and the transistor Q
The series circuit of I Qx and the series circuit of transistors Q3 and Q4 are connected in parallel, and the transistor QI Q! and the connection point of the transistor Q s Q4 are connected to the output terminals 16m and 16b, respectively, through the waveform correction low-frequency wave filter 32. The p-wave device 32 consists of a coil 321 and a capacitor 32e. A diode DI"'D4 is connected in parallel to each of the transistors Ql-Q4 with opposite polarity. A capacitor 33 is connected in parallel to the series circuit of the transistors QI and Q2, and a Storage batteries 14 are connected in parallel.

A transformer 36 for detecting the input AC voltage V0 is connected between the input terminals 12a and 12b, and a current transformer 37 for detecting the load current It is coupled to the load (output) current path between the AC switch 18 and the output terminal 16a. p-wave device 32
A transformer 38 for detecting inverter output voltage v1n is connected to the output side of
9 are combined. Furthermore, a current detection circuit 41 is inserted in series between one end of storage battery 14 and one end of capacitor 33 to detect battery current It. These detection voltages V,.

vin, detection current Izy11n+Ib, and storage battery 14
The voltage vb is supplied to the control device 42.

FIG. 3 shows a specific example of the control device 42. In this example, the commercial power and the inverter output are switched in synchronization with each other, and the inverter 15 uses a pulse width modulation method. Therefore, the detected input AC voltage v
ac is input to the power failure detection circuit 19, and when the voltage vac falls below a predetermined value, it outputs a high level, and this high level output switches the switch 26.43 from the 1 side to the 2 side. In a commercial power receiving state where the input AC voltage v&c is equal to or higher than a predetermined value, the output of the power failure detection circuit 19 is at a low level, and the switch 26.43 is on the 1 side. The input AC voltage vlLo detected in this state is shaped into a rectangular wave by the waveform shaping circuit 44, and is passed through all the switches 43 to a phase locked loop (PLL).
45 to the phase comparator 46 of the voltage controlled oscillator 4.
The phase is compared with the output of 8. The output of the phase comparator 46 is passed through a loop filter 47 to a voltage controlled oscillator (VCO).
) 48, and the output of the oscillator 48 is phase-locked to the input AC voltage. The output of the oscillator 48 is supplied to the second side of the switch 26 through a multiplier 49 and a differential amplifier 51. The output of the switch 26 and its inverted output are each compared with the output of the triangular wave generator 53 by a comparator 52at52b, and a comparator 52a.

A pulse width modulated output is obtained from 52b. When a power outage is detected by the power outage detection circuit 19, the switch 26° 43 is switched to the 2 side as described above, and the output of the oscillator 54 at the commercial power frequency, which is based on a stable oscillator such as a crystal, is output to the phase comparator. 46, and the output of the oscillator 48 is supplied to the multiplier 4.
9, the signal is supplied to the comparator 52 through the differential amplifier 51 and the switch 26. On the other hand, the output of the power failure detection circuit 19 is applied to an AND circuit 57 through an inversion circuit 55 and a delay circuit 56. Loop filter 4 of phase locked circuit 45
7 is supplied to the synchronization detection circuit 58, and when the synchronization state is reached, the output of the loop filter 47 is at a low level, and the output of the synchronization detection circuit 58 is at a high level. Therefore, when the switch 43 is switched to the 2 side, the output of the synchronization detection circuit 58 generally becomes low level immediately, and the AND circuit 57
The output of the dirt pulse generating circuit 59 is also at a low level, so that the output of the dirt pulse generating circuit 59 is at a low level, and the AC switch 18 in FIG. 2 is cut off. Therefore, when the commercial power supply fails, the computer becomes operational in synchronization with the previous commercial power supply.

A portion related to the inverter operation in FIG. 3 is shown in FIG. The sine wave supplied by the switch 26 is shown, for example, by a curve 61 in FIG.
In the portion where the level is higher than 2, the output of the comparator 52m is at a high level υ, and the rectangular wave shown in FIG. 5B is obtained from the comparator 52a. Similarly, a rectangular wave shown in FIG. 5C is obtained from the comparator 52b. These rectangular waves B and C in FIG. 5 are supplied to the switch control/4/L/S generator 63, and
, C are applied to the bases of transistors Ql and Qs in FIG.
A switching signal having a waveform that is an inversion of the waveform shown in is applied to transistors Q2+Q4(7)R-. The base of these transistors Ql=Q4 is on at high level,
Controlled off at low levels.

Therefore, in a section where the rectangular wave in FIG. 5B is at a high level and the rectangular wave in FIG. 5C is at a low level, transistors Ql and Q4 are turned on and Q! .

Qs is turned off, and the inverter current Iin flows from the storage battery 14 through the transistor Ql, the wave generator 32, the load 17, and the transistor Q4. In the section (3) in which both the rectangular waves in FIG. 5B and C are at a high level, as shown in FIG. 6B, transistors Ql and Qs are on, Q2 and Q4 are off, and the coil 32t of the door transducer 32 is turned on.

The energy stored in capacitor 32c is released through load 17° diode D3 and transistor Ql.

Next, the rectangular wave shown in FIG. 5B is at a high level and the rectangular wave shown in FIG. This operation is performed in the positive half cycle of the sine wave 61, and in the negative half cycle, transistors Qx-Qs are mainly controlled in the same way, and a sixth transistor is connected in the load.
Current flows in the opposite direction to those shown in Figures A, B, and C. If Toba device 3
2 is omitted, a positive pulse flows through the load 17 in the positive half cycle of the sine wave 61 as shown in the fifth diagram, and the sine wave 6
A negative No. 9 rus flows in the negative half cycle of 1.

A sine wave having the same frequency as the sine wave 61 is extracted by the door wave generator 32, and AC power is supplied to the load 17.

The level of this AC power is i4 /v in the fifth diagram.
Varies depending on the width of the space. When the amplitude of the sine wave 61 is Vl and the amplitude of the triangular wave 62 is vtr, the pulse width modulation index M of the output pulse is vs/Vtr, and when the modulation index M is small, the output level of the inverter 15 becomes small.

In order to keep the output of the inverter 15 constant, the detected inverter voltage vln is supplied to the differential amplifier 51 as shown in FIG. (Conversely, if the detected inverter voltage vln is small, the amplitude of the output of the differential amplifier 51 is large), so that the inverter voltage vln always remains at a constant value.

In addition, the detected inverter current "in" is the rectifier smoothing circuit 6
4, and the difference between the output and the output of the current reference power supply 65 is detected by the differential amplifier 66.
The amplitude of the sine wave output of the voltage controlled oscillator 48 is controlled by the multiplier 49 based on the output of the voltage controlled oscillator 48. If the inverter current 11n is smaller than the reference value, the output sine wave amplitude of the multiplier 49 is small, and if the inverter current 11n is larger than the reference value, the output sine wave amplitude is controlled to be small. As a result, the inverter 15 operates so that the output light weight ln always remains at a constant value.The detected inverter light weight ln is also supplied to the peak comparator 67 and compared with the reference value of the reference power supply 68.Inverter current Iln When the peak value of exceeds the reference value, the output of the peak comparator 67 goes to a high level, and the flip-flop 71 is set through the gate 69 (opened by the output of the power failure detection circuit 19). The output stops the operation of the switch control-4' pulse generation circuit 63.The output of the triangular wave signal generator 53 is sent to the reset terminal R of the flip-flop 71 through the differentiating circuit 72.
The fritz float 7'71 is reset every cycle of the triangular wave 62.

Charging Operation When the power outage is restored, the output of the power outage detection circuit 19 is at a low level, and the switch 26.43 is switched to the 1 side in FIG. . When the voltage controlled oscillator 48 is synchronized with the input commercial power, the output of the synchronization detection circuit 58 becomes high level, and the delay circuit 56 has a delay time of about 10 seconds, for example.
A high level is applied to the AND circuit 57 after sufficient time has elapsed for the power to be restored, the commercial line to be stabilized, and to reach a synchronized state. When the output of the AND circuit 57 becomes high level, the r-) pulse is generated from the gate pulse generation circuit 59 and the second
AC switch 18 in the figure is turned on, and commercial power source power from terminal 12 is supplied to load 17 .

In this state, the storage battery 14 is charged from the commercial power source 11 through the battery 15.

A portion of FIG. 3 related to this charging operation is shown in FIG. 7. The oscillation output of the VCO 48 is supplied to a multiplier 73. Detection storage battery lightning heavy voltage VB is the reference power supply 74.7 respectively
5 is detected by the differential amplifiers 76 and 77, and these detection outputs are added by the adder 78 and sent to the multiplier 73.
supplied to When the detected storage battery voltage vb becomes smaller than the reference value, the output of the differential amplifier 77 becomes negative, the output of the adder 78 becomes large, and the output amplitude of the multiplier 73 becomes negative. This output is led to the adder circuit 79 of the synthesis circuit 25 and further to the differential amplifier 81, and the inverter is controlled so that the difference from Iin becomes O. On the other hand, when the storage battery 14 is fully charged, the output of the adder 78 becomes small and the output of the multiplier 73 approaches zero, thereby reducing the charging current.

The number of peaks of the inverter 15 is 1 for the voltage vb of the storage battery 14.
(below) Ashi, while the battery voltage vb is the nominal value vb8
The lowest battery voltage O,
S Vb, is equal to the normal input AC voltage v&c when the inverter output voltage is in operation, so V, ≧v&c
If the peak value is , the storage battery 14 will not be charged from the commercial power source 11 when the inverter is not operating. However, by operating the inverter 15, the charging voltage vb is reduced to 1,
s (2) ae or higher, and therefore the storage battery can be charged.

AC voltage ■. In the positive half cycle of the transistor Qt
Turning on Q4 and turning on QIQs are repeated. Now the 8th
As shown in Figure 9, the input AC voltage v&e is lower than the battery voltage vb, and as shown in Figure 8B, in interval I where vtn-v&c is positive, as shown in Figure 9, transistor QI
When Q4 is turned on, the battery 14 becomes the transistor Q! , the coil 321 of the F wave generator 32 - the commercial power supply 11 - the transistor Q
4, current Ib flows as shown in FIG. 8C. Then transistor QIQs is turned on and the inverter output v1
In the section ■ where n is set to zero, as shown in FIG. 9B, the commercial power supply 11, the υ coil 32t, and the diode DI.

Direct current flows to the inverter 15 side through the transistor Q3, and energy is stored in the coil 321.

Then transistor QI Q4 f is turned on again,
The voltage accumulated in the coil 321 and the commercial power supply voltage v0 are added, and the result is 2x1c. Therefore, as shown in FIG. A charging current flows through 14. After the energy of the coil 32t is released, a current flows from the storage battery 14 to the commercial power source 11 as in section (3). The storage battery 14 is charged by selecting the value of M such that the integral value of the charging current on the negative side is larger than the integral value of the discharging current on the positive side in FIG. 8C. In the negative half cycle of the alternating current voltage "ac", transistors Qx and Qs are turned on and Q
2 Repeat Q4 on. When the modulation index M is decreased, the charging current can be increased (the relationships between A, B, and C in FIG. 8 are as shown in A, B, and C in FIG. 10).

Note that when the storage battery 14 is sufficiently charged, the battery voltage vb, the reference value of the reference power source 82 and the total comparator 83
The dart/elder pulse generating circuit 84 is compared with this output.
to control that goo) to stop the generation of 4rus, and to
It is preferable to turn off the switch 35 shown in the figure to prevent current from flowing into or out of the storage battery 14.

Harmonic Removal Operation As described above, while receiving commercial power, harmonic components in the load current are removed using the inverter 15. FIG. 11 shows the portion in FIG. 3 related to the expulsion operation. 11th
The figure shows a case in which a reduction in power factor due to a phase shift in voltage and current due to the load is simultaneously improved. The detected load current 1t is supplied to the adder circuit 86 and also to the narrow band door filter 87 to obtain its fundamental wave component Imgtn(
ωt+θ) is extracted, the peak value - of the fundamental wave component is detected by the peak value detection circuit 88, and is also supplied to the phase detector 89, where the phase difference θ with the output ratio ωt of the VCo 48 is detected. The cosine value surface θ of the detected phase difference θ is stored in the memory 9.
1, and the multiplier 92 multiplies the peak value and the detected peak value. This multiplication output Irn(2)θ and the output ratio ωt of the VCo 48 are multiplied by a multiplier 93,
As this output, 1m(2)θ-ro ωt(1) is obtained. The difference between the output and the detected load light weight 6 is calculated by an adder circuit 86. The detection load electric light weight t is the harmonic component f(nω
), then 11=I,, 4(ω is 10)+J'(nω)=Inl
ccm θ bit ω to 10 m-zuke(ωt + 2) +f
It is expressed as (nω) (2). The difference output of the adder circuit 86 passes through the adder circuit 79, and the difference with the detected inverter current Iin is detected by the differential amplifier 81, and the output of the differential amplifier 81 is supplied to the comparators 52a #52b. As a result,
It operates so that the output of the differential amplifier 81 is zero and the output of the adder circuit 86 is equal to the detection inverter light weight ln. The inverter operates so that l1n=-It+lff1g,f)・蜘ωt(3), and this inverter light weight tn is supplied from the inverter 15 to the output terminal 16, which is added to the load current It, and the load The current It=IrncQgθ・ωt. In this way, the harmonic component of the load current in the third term of equation (2) is removed, and in this example, the second term of equation (2)
The term component is also removed and the power factor is also brought to unity. In addition, when removing only harmonic components, the phase detector 8 in FIG.
9. The memory 91 and multiplier 92 may be omitted. Further, in the case of improving only the power factor, the output of VCo 4 B and the load current It may be subtracted by the adding circuit 86, and the output may be supplied to the differential amplifier 81.

When removing harmonic components, it may be necessary to change the voltage across the capacitor 33 in FIG. 2 by a considerable amount.

In that case, average the current shown by the dotted line in Figure 2,
It is preferable to short-circuit the inductance element 95 during inverter operation. Or addition circuit 86
The peak value of the detected harmonic branch component obtained in the output of the capacitor 33 may be suppressed to some extent to prevent the capacitor 33 from being rapidly charged and discharged.

In the above description, a one-phase high-frequency pulse width modulation method is used as the inverter 15, but a three-phase one may be used.

Further, in order to remove harmonic components, a high frequency pulse width modulation method is preferable since all control is performed during one cycle of the commercial power supply. A transformer may be inserted between the door wave device 32 and the output terminals 16ay16b.

``Effects of the Invention'' As described above, according to the present invention, the charger is omitted and the inverter, which was conventionally inactive or on standby with no load, is used to charge the storage battery when commercial power is received, and the storage battery is charged. Moreover, harmonic components included in the load current can be removed using the output stabilization control section of the inverter, and there is no need to use a special filter for removing harmonic components. Further, although the inverter 15 is used for charging and removing harmonics in this way, there is also an advantage that the control section used when operating the inverter can be used as is for controlling this purpose.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of a standby uninterruptible power supply according to the present invention, and Figure 2 is an inverter switch circuit 3.
A connection diagram showing a specific example mainly of one part, Fig. 3 is the second part.
A block diagram showing a specific example of the control device 42 in the figure, FIG. 4 is a diagram showing a part related to the inverter operation in FIG. 3,
FIG. 5 is a waveform diagram for explaining the inverter operation.
Fig. 6 is a connection diagram showing the current flow in sections I, n, and III in Fig. 5, Fig. 7 is a diagram showing the part related to the charging operation in Fig. 3, and Fig. 8 is during the charging operation. FIG.
A diagram showing the flow of current in sections r, u, and m in the figure, Figure 10 is a diagram corresponding to Figure 9 when the modulation index is reduced, and Figure 11 is the harmonic component removal in Figure 3. FIG. 12 is a block diagram showing a conventional floating charging type uninterruptible power supply, and FIG. 13 is a block diagram showing a conventional standby type uninterruptible power supply. 11: Commercial power supply, 12: Input terminal, 14: Storage battery, 15
: inverter, 16: output terminal, 17: load, 18: AC switch, 19: power failure detection circuit, 21: inverter fluctuation detection section, 22: inverter control section, 23: harmonic detection section, 24: battery fluctuation detection section, 25: Synthesis circuit, 26: Switch.

Claims (1)

[Claims] (1) Supply commercial power supply power to the load through an AC switch and further through an output terminal, turn off the AC switch in the event of a power outage, convert the output of the storage battery to AC power with an inverter, and supply it to the output terminal, and In an uninterruptible power supply that detects fluctuations in output and uses the detected output to control a control section of an inverter to suppress the fluctuations, harmonic detection means detects harmonic components included in the current flowing through the load; , When power is being supplied from the commercial power source to the load,
harmonic suppression means for operating the inverter to suppress harmonic components of the current flowing through the load by supplying the detected harmonic components to the control unit in place of the fluctuation detection output; A charging means is provided for operating the inverter while supplying AC power to the load, operating the inverter as a charger, and charging the storage battery with the AC power. Standby uninterruptible power supply.