JPH0628927Y2 - Standby uninterruptible power supply - Google Patents

Description

[Detailed Description of the Device] “Industrial Application Field” This device is used, for example, as a power supply for a small computer. When the commercial power supply is normal, the commercial power is directly sent to the load, and when the commercial power fails, the DC of the storage battery The present invention relates to a standby uninterruptible power supply device which converts an output into an alternating current by an inverter and supplies it to a load.

"Prior Art" Generally, as a small uninterruptible power supply, the floating charging system shown in Fig. 8 has been widely used because of its simple structure. AC power from the commercial power supply 11 is supplied from the input terminal 12 to the charger 1
3 to supply DC power, and the DC power is supplied to the storage battery 14
To the inverter 15 as well as to charge,
The inverter 15 converts the AC power into AC power and supplies the AC power to the load 17 through the output terminal 16. However, this conventional device is operated by the charger 13 while receiving commercial power.
Must supply the total power of the input power to the inverter 15 and the charging power to the storage battery 14, which makes it difficult to miniaturize the charger 13 and outputs the commercial power to the output terminal 16 when receiving the power. Since the output power is supplied through the two converters of the charger 13 and the inverter 15, there is a problem that the power loss in these two converters is large and the input power is correspondingly large.

As a countermeasure for this, a standby uninterruptible power supply with a high-speed switching circuit for energy saving and downsizing has been adopted. This stand-by type device focuses on the fact that most commercial devices such as small computers can continue operation without any effect when the power is interrupted for 10 ms or less. That is, as shown in FIG. 9, while the commercial power is being received, the AC power from the input terminal 12 is directly sent to the output terminal 16 through the AC switch 18 capable of high-speed switching, and the AC power from the input terminal 12 is passed through the charger 13 to the storage battery. 14 is charged, and the inverter 15 performs a no-load operation in synchronization with commercial power. If the commercial power supply is momentarily cut off or the voltage drops, the AC switch 18 is turned off and the power of the inverter 15 is switched to the output terminal 16 and supplied in about 1/4 cycle (5 ms) to allow the load to continue operating. . In this standby system, the charger 13 only needs to supply the no-load power of the inverter 15 and the charge for the storage battery 14, and the power capacity of the charger 13 is about 1/5 that of the floating charging system. And the effect of energy saving were great.

"Problems to be solved by the invention" This invention eliminates a conventional dedicated charger by using an inverter that is conventionally in a standby state as a charger for a storage battery while receiving commercial power. (EN) Provided is a standby type uninterruptible power supply device which is simple and can be miniaturized and can be reduced in price. Japanese Patent Office Sho 59
Japanese Patent Laid-Open No. 37653 proposes a method in which an inverter is started while a commercial power is being received, a storage battery is charged with a commercial voltage, and a charger is omitted. However, the one disclosed in this publication creates a phase difference reference for the charge control of the storage battery from the difference between the voltage of the storage battery and the reference voltage, and detects the phase difference between one commercial voltage and the output voltage of the inverter. Is detected, the difference between the detected output and the phase difference reference is calculated, and the oscillation frequency of the reference oscillator for PWM generation is controlled so that the difference becomes zero. Therefore, a relatively large number of configurations such as a phase difference detection circuit and an oscillation frequency control loop of an oscillator are required, which is disadvantageous in that it is expensive.

[Means for Solving Problems] According to the present invention, in the standby uninterruptible power supply, while the AC switch is turned on to receive commercial power, one of a pair of output terminals of the inverter bridge circuit and the storage battery The two switch elements connected between the two ends of the power supply are alternately enabled to operate in synchronization with the commercial power supply voltage, the commercial voltage is used as the reference signal, and the fluctuation detection output of the storage battery is the inverter output fluctuation detection output. Instead of the above, it is supplied to the multiplier and is intermittently controlled by the pulse width modulation signal from the pulse generator controlled by the output of the multiplier to make the switch element in the operable state intermittently stored in the inductance element of the wave device. The voltage of energy and the voltage of the commercial power source are added to charge the storage battery through the bridge circuit of the inverter. In other words, in this case, the storage battery voltage is set so that the peak value of the commercial power supply voltage does not exceed the storage battery voltage, and the energy stored in the inductance element of the wave device for shaping the inverter output into a sine wave while receiving commercial power. Is added to the commercial voltage to obtain a voltage higher than the storage battery voltage, and the storage battery is charged.

[Embodiment] FIG. 1 shows an embodiment of a standby type uninterruptible power supply according to the present invention. One input terminal 12a is connected to one output terminal 16a through a high speed AC switch 18 such as a thyristor, and the other input terminal 12b and the other output terminal 16 are connected.
b are directly connected to each other. The storage battery 14 is an inverter 15
Connected to the input terminals 22 and 23 of the bridge circuit 21 and the output terminals 24 and 25 of the bridge circuit 21 through the low pass wave filter 26 for waveform shaping into a sine wave.
a, 16b.

The bridge circuit 21 is a case where the transistors Q _{1 to} Q ₄ are used as _four switch elements, the transistors Q ₁ and Q ₂ are connected in series in the forward direction, and both ends thereof are connected to the input terminals 22 and 23, Transistors Q ₃ and Q ₄ are also connected in series in the forward direction, and both ends thereof are connected to input terminals 22 and 2.
3, the connection points of the transistors Q ₃ and Q ₄ are connected to the output terminal 24, and the connection points of the transistors Q ₁ and Q ₂ are connected to the output terminal 25. Transistor Q ₁ ~
Diodes D _{1 to} D in parallel with Q ₄ and having opposite polarities
₄ is connected. A control signal is applied from the control device 27 to the bases of these transistors Q _{1 to} Q ₄ to perform on / off control, and current is intermittently supplied from the storage battery 14 to the wave filter 2.
6 and is output to the output terminal 1 as a sine wave by the wave device 26.
It is supplied to 6a and 16b. A capacitor 28 is connected between the terminals 22 and 23. The wave filter 26 is composed of an inductance element 29 and a shunt capacitor 31 in series.

The voltage on the output side of the wave device 26 is detected by the transformer 32 as the inverter voltage V _in , and the current flowing between the wave device 26 and the output terminal 16b is detected as the inverter current I _in by the current transformer 33, and the storage battery 14 and the terminal 23 are detected. The current flowing between the battery current and the current detection circuit 34
Detected as I _b . These detection voltage V _in, the detection current
I _in , I _b , the battery voltage V _b across the capacitor 28, and the input AC voltage V _ac between the input terminals 12 a, 12 b are supplied to the controller 27, respectively.

Control Device FIG. 2 shows a specific example of the control device. The transistor Q ₁ to Q ₄ of the bridge circuit 21 on-off controlled at a frequency higher than the commercial power frequency, and can be the change of the on-off period, that is, pulse width modulation varies the amplitude of the sine wave of the inverter output Is being done. In addition, in this example, the inverter operates in synchronization with the commercial power supply up to that point in the event of a power outage, and when the power is restored, the inverter output is switched to commercial power in synchronization with the restored commercial power. is there. Therefore, in the control device 27, the detected input AC voltage V _ac is supplied to the power failure detection circuit 41 and the waveform shaping circuit 42. The waveform shaping circuit 42 converts the input sine wave into a square wave and supplies it to the phase detection circuit 45 of the phase synchronization circuit 44 through the changeover switch 43.
The output (reference signal) of the oscillator 46 including a stable oscillator such as a crystal oscillator and a frequency divider and having a frequency equal to the commercial power supply frequency is connected to the phase detection circuit 45 through the changeover switch 43. In the phase detection circuit 45, the switch 43
Input from, and voltage controlled oscillator (hereinafter referred to as VCO) 47
The phase difference from the sine wave output of the VCO 47 is detected, the detected output is supplied as a control signal to the VCO 47 through the loop filter 48, and the oscillation frequency and phase of the VCO 47 are controlled so as to be synchronized with the output of the switch 43. The output of this VCO 47 is passed through a multiplier 49 to a comparator 52 in a pulse generator 51,
It is supplied to the non-inverting input terminal and the inverting input terminal of 53, respectively.

A triangular wave signal having a constant amplitude higher than the commercial power frequency is input from the triangular wave generator 54 to the other input terminal of each of the comparators 52 and 53, and the output of the comparator 52 passes through an inverting circuit and further to a delay circuit. Gate 56 through 55
To the gate 58 through the delay circuit 57. The output of the comparator 53 is supplied to the gate 61 through the inverting circuit, the delay circuit 59, and the gate 63 through the delay circuit 62. The outputs of the gates 56, 58, 61 and 63 are supplied to the bases of the transistors Q _{1 to} Q ₄ through amplifiers 64 to 67 as needed. Delay circuits 55, 57, 59, 62
Are for slightly delaying the rising of the input so that the bridge circuit 21 (FIG. 1) is not short-circuited.

Inverter operation When the power failure detection circuit 41 detects a power failure, its output becomes high level, and the changeover switch 43 is switched to the oscillator 46 side by the high level, and the inverter operation is performed. FIG. 3 shows a portion related to this inverter operation in FIG. The output of the power failure detection circuit 41 is the fall delay circuit 68.
Is supplied to the gates 56 and 58 through the gates and is also supplied to the gates 61 and 63 through the OR circuits 69 and 71, respectively. Therefore, the gates 56, 58, 61 and 63 are opened, the transistors Q _{1 to} Q ₄ are on / off controlled by these outputs, and the sine wave output of the commercial power supply frequency is obtained from the output of the wave device 26 in FIG. . When the output waveform of the multiplier 49 supplied to the comparators 52 and 53 is the curve 91 of FIG. 4A and the output triangular wave of the triangular wave generator 54 is the curve 92, the outputs of the comparators 52 and 53 are respectively shown in FIG. As shown in B and C, this output causes the transistor Q ₂
And _{Q 4} are off.

Similarly, the transistors Q ₁ and Q ₃ are turned on / off by a switching signal having a waveform obtained by inverting the waveforms shown in FIGS. 4B and 4C, respectively. An inverter fluctuation detection unit 72 is provided to keep the inverter output constant.
That inverter voltage V _in that is detected rectifier circuit 73
Is rectified, and the rectified output is compared with the reference value of the reference power supply 74 by the error amplifier 75, and the difference is supplied to the adding circuit 76. Further, the detected inverter current I _in is rectified by the rectification circuit 77, and the reference value of the reference power supply 78 and the error amplifier 7 are rectified.
Then, the difference is supplied to the adder circuit 76. The output of the adder circuit 76 is supplied to the changeover switch 81 as the output of the inverter change detection unit 72. Changeover switch 81
Is also supplied with the output of the battery output fluctuation detecting unit 82, and is switch-controlled by the output of the fall delay circuit 68. During the power failure, the output of the inverter fluctuation detecting unit 72 is taken out, and the output of the switch 81 thereof is used to multiply the multiplier 49. Controls the amplitude of the input sine wave. For example, when the detected inverter voltage V _in decreases, the output of the error amplifier 75 increases in the positive direction, and the positive output increases the amplitude of the sine wave output from the multiplier 49, resulting in an output voltage of the wave device 26, that is, V _in Becomes larger,
Hold the inverter voltage V _in constant. Similarly, when the inverter current I _in fluctuates, it operates so as to suppress it.

The above operation is similar to the operation in the conventional pulse width modulation type inverter. The detected inverter current I
_In is also supplied to the peak detection circuit 83, and the detected peak value and the reference value of the reference power supply 84 are compared by the comparator 85. When the detected peak value exceeds the reference value, the output of the comparator 85 becomes high level. , This is supplied to the flip-flop 87 through the gate 86, the flip-flop 87 is set, the output of the flip-flop 87 becomes low level, the output closes the gates 56, 58, 61 and 68, and the transistors Q _{1 to} Q ₄ ON / OFF control is stopped, that is, the inverter operation is stopped. The gate 86 is opened by the output of the delay circuit 68. The output of the triangular wave generator 54 is differentiated by the differentiating circuit 88, the flip-flop 87 is reset by the differentiated output, and the flip-flop 87 is reset for each cycle of the triangular wave.

The inverter output voltage V _in is the battery voltage V _b , the modulation index is M
Then, Given in. The modulation index M is the amplitude V _tr of the triangular wave 92,
It is a value V _s / V _{tr obtained} by dividing the amplitude V _s of the sine wave 91. When the modulation index M is overmodulated to 1.0 or more, the lower harmonics increase,
Since it becomes difficult to sufficiently cut off this with the small wave filter 26, M is set to 1.0 or less. In other words, when M = 1.0, the inverter output voltage is maximum, and the value at that time is Is. Output terminal 1 keeps constant voltage even if battery voltage V _b fluctuates
In order to keep the output voltage constant even when the battery voltage V _b fluctuates ± 20%, it is necessary to output to the inverter 6 (V _bs is the nominal voltage of the storage battery 14) must be equal to the commercial power supply voltage V _ac . That is, , Therefore Therefore, it is necessary to make the battery voltage V _b larger than the peak value of V _ac .

Charging Operation When the power failure is restored, the output of the power failure detection circuit 41 becomes low level, and the changeover switch 43 is immediately switched to the waveform shaping circuit 42 side. Therefore, the oscillation of the VCO 47 operates in synchronization with the restored commercial power source. The delay circuit 68 delays the fall of the output of the power failure detection circuit 41 by at least the time required for synchronization, the changeover switch 81 is switched to the battery fluctuation detection unit 82 side by the output, and the gate pulse generation circuit 93 is driven. The output from this switch turns on the AC switch 18 in FIG. That is, the AC switch 18 is turned on after the output supplied to the load 17 by the inverter is synchronized with the commercial power output, and the commercial power 11
The electric power from the electric power source is supplied to the load 17.

In this invention, the storage battery 14 is charged by operating the inverter while receiving commercial power. As described above, since the nominal voltage V _bs of the storage battery 14 is set to 1.77 V _ac or higher, that is, higher than the commercial power supply voltage V _ac , in the present invention, the inverter is controlled so that the inductance element 29 of the wave filter 26 is controlled. Energy is stored, and the voltage of the inductance element 29 at this time and the AC input voltage V _ac are added to the storage battery 14
To charge.

FIG. 5 shows the portion related to the charging operation in FIG. Since the output of the delay circuit 68 becomes low level, the gate 56,
58 is closed, thus keeping transistors Q ₁ Q ₂ off. The output low level of the delay circuit 68 is set to a high level by the inverting circuit 94 and supplied to the gates 95 and 96 to open the gates 95 and 96. The outputs of the gates 95 and 96 are supplied to OR circuits 69 and 71, respectively. On the other hand, the output of the waveform shaping circuit 42 is directly inverted and supplied to the gate 95, and is also supplied to the gate 96 without being inverted.

Therefore, in the positive half cycle of the commercial power output, the gate 96,
63 is opened, and the output of the comparator 53 causes the transistor Q
Only ₄ is turned on and off. When the transistor Q ₄ is turned on, a current flows from the commercial power source 11 through the inductance element 29, the transistor Q ₄ and the diode D ₂ as shown in FIG. 6A, and when the transistor Q ₄ is turned off next, the inductance element 29 is turned on. If the voltage due to the energy stored in the battery and the voltage of the commercial power source 11 are added, the voltage becomes about twice, and if this voltage is higher than the voltage V _{b of the} storage battery 14,
The inductance element 29-diode _D from the commercial power source 11 as shown in FIG. B ₃ - a charging current flows through the battery 14 the diode _{D 2.}

In the negative half cycle of the commercial power supply 11, the gate 95,
61 is opened, and the output of the comparator 53 causes the transistor Q ₃
Only controlled on and off. Also in this case, the transistor Q
₃ is turned on, energy is stored in the inductance element 29, and when the transistor Q ₃ is turned off, the commercial power source 1
1 to diode D ₁ , storage battery 14, diode D ₄ ,
A charging current flows through the inductance element 29 to charge the storage battery 14.

This state is shown in FIG. In FIG. 7A, the curve 97 shows the commercial power supply voltage, and FIG. 7B shows the square wave output for the positive / negative judgment of the commercial power supply voltage output from the waveform shaping circuit 42. In the positive half cycle, it is shown in FIG. 7C. As shown, the transistor Q ₄ is on / off controlled, and as a result, the commercial power supply voltage V
The added voltage V _ch of _ac and the voltage of the inductance element 29 is as shown by the curve 98 in FIG. 7A, which is the battery voltage.
When it exceeds V _b , the charging current flows as shown in FIG. 7E. In the negative half cycle, the transistor Q ₃ is on / off controlled as shown in FIG.
Since the battery voltage V _b is set higher than the commercial power supply voltage V _ac , there is no possibility that an unlimited current will flow into the storage battery 14 and damage the storage battery when the inverter 15 is not operating.

When the storage battery 14 is charged with a constant voltage and a constant current, the battery fluctuation detection unit 8 is operated as shown in FIGS. 2 and 5.
In 2, the detected battery current I _b is compared with the reference value of the reference power supply 101 by the error amplifier 102, and the error output is supplied to the addition circuit 103. Further, the detected battery voltage V _b is compared with the reference value of the reference power source 104 and the error amplifier 105, and the error output is supplied to the adding circuit 103, and the adding circuit 10
The output of No. 3 is supplied to the multiplier 49 through the changeover switch 81 as the output of the battery fluctuation detection unit 82. As a result, the charging current I _b and the charging voltage V _b are made constant.

In the above description, the charge control for the storage battery 14 is performed by turning on / off the transistors Q ₃ Q ₄ , but the transistors Q ₁ Q ₂ are selected according to the positive half cycle and the negative half cycle of the commercial power source to perform the on / off control. Then, charging can be performed similarly. Further, the on / off control of the transistor is sine wave modulated, but the power factor between the current flowing to the load 17 and the applied voltage can be improved by appropriately selecting the phase. In the above example, the switching control is sinusoidal modulated at the time of charging, but it may be turned on / off at a constant cycle.

[Advantage of Device] As described above, according to the standby type uninterruptible power supply device of the present invention, the storage battery can be charged using the inverter while the commercial power is being supplied to the load. The control for charging is the OR circuits 69 and 71, the gate 9
Without adding significant changes to the addition of 5,96,
The bridge circuit of the inverter and its control unit can be used, and a dedicated charger is not required. For this reason, it becomes possible to reduce the cost and to make it compact. Further, the storage battery is charged only as much as necessary, and the charging efficiency is good and the life of the storage battery is long as compared with the case of performing charging as a whole while performing charging and discharging.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an example of a standby type uninterruptible power supply device according to the present invention, FIG. 2 is a block diagram showing a concrete example of the control device 27 shown in FIG. 1, and FIG. 3 is an inverter shown in FIG. FIG. 4 is a diagram showing a portion related to the operation, FIG. 4 is a diagram showing an example of a relation between a sine wave, a triangular wave and an output of a comparator during an inverter operation, and FIG. 5 is a portion relating to the charging operation in FIG. FIG. 6, FIG. 6 is a diagram showing a current flow of the bridge circuit 21 during a charging operation, and FIG. 7 is a diagram showing a relational example of commercial power supply voltage, transistor on / off, charging current, etc. during the charging operation, and FIG. FIG. 1 is a block diagram showing a conventional floating charging type uninterruptible power supply device, and FIG. 9 is a block diagram showing a conventional standby type uninterruptible power supply device. 11: Commercial power supply, 12, 12a, 12b: Input terminal, 1
4: Storage battery, 15: Inverter, 16, 16a, 16
b: output terminal, 17: load, 21: bridge circuit, 2
7: Control device.

Claims (1)

[Scope of utility model registration request] 1. An AC switch is connected between an input terminal to which a commercial power source is connected and an output terminal to which a load is connected, and a low range including an inductance element at a connection point between the AC switch and the output terminal. The output side of a high-frequency pulse-width modulation type inverter is connected through a passing wave device, and the inverter has a bridge circuit consisting of a plurality of switch elements and a pulse generator that outputs a high-frequency pulse-width modulation signal for controlling each of these switch elements. , A storage battery is connected to the input side of the inverter, the AC switch is turned off in the event of a power failure, and the output that detects fluctuations in the output of the inverter and the reference signal of the same frequency as the commercial power supply are multiplied by a multiplier. The output is supplied to the pulse generator to operate the inverter, and the DC power of the storage battery is converted to AC power. In the standby type uninterruptible power supply device for supplying to the output terminal, means for detecting the fluctuation of the storage battery, and one of the pair of output terminals of the bridge circuit and both ends of the storage battery while the AC switch is turned on. Means for making only the two switching elements connected between the switch and the commercial power supply possible to operate alternately in synchronism with the voltage of the commercial power supply, and the voltage of the commercial power supply while the AC switch is turned on. For supplying the fluctuation detection output of the storage battery to the multiplier instead of the output fluctuation detection output of the inverter, and charging the storage battery through the inverter with the commercial power supply. The standby type uninterruptible power supply characterized by the above.