JP2956372B2 - Uninterruptible power system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply (hereinafter referred to as U
PS) and a rectifier. More specifically, the present invention relates to a UPS and a rectifier that converts DC power from a battery or the like into AC power at the time of a power outage of an AC power supply and outputs the AC power to both an output side and an input side.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional example of an AC uninterruptible power supply (UPS). Although a single-phase circuit is used as an example, a three-phase circuit is similarly used. The UPS 34 includes an input converter 3, a battery B, and an AC output converter (hereinafter referred to as an inverter) 4AC. Reference numerals 30 and 40A denote control devices for the input conversion unit and the output conversion unit, respectively. The input conversion unit 3 includes switches S ₁ to S ₁ in which a semiconductor switching element (hereinafter, referred to as a transistor) and a diode are connected in anti-parallel.
The bridge circuit is constituted by S _4, the reactor L _IN, a capacitor C. PT _IN is a transformer for sensing the voltage of the AC power supply. CT is a current transformer for sensing an input current. Bridge circuit output conversion unit 4AC was a switch S ₅ to S ₈ connected in antiparallel with the transistors and diodes, a reactor L _AC and capacitor C _AC
And an output transformer T. PT
_OUT is a transformer for sensing the output voltage, and 7AC is a conversion load.

Next, the operation will be described. Switches S _{1 to} S ₄
The bridge circuit composed of rectifies the voltage of the AC power supply, charges the capacitor C and the battery B, and supplies power to the inverter 4AC. Simply switch S ₁ to S ₄ when only rectified only feature diodes play. A transistor connected in anti-parallel to the diode is provided to control the waveform of the input current. The purpose is to set the power factor to 1 by making the input current of the device a sinusoidal waveform in phase with the voltage of the AC power supply, and to suppress the generation of harmonics. UPS viewed from the AC power supply side
Is equivalent to a pure resistance, which is an ideal load. The power supply waveform control mechanism will be described next. For example, AC power supply 1
When the polarity of turn on the transistor of the switch S ₂ at 7, all the transistors of the switches S ₂ of the voltage of the AC power supply 1 is applied to the reactor L _IN in a loop to make the diode of the switch S _4, to Electromagnetic energy is stored by the flowing current. Next, when turning off the transistor of the switch S _2, the current of the reactor L _IN switches S _1, flows through S ₄ of the diode capacitor C
Energy is released to the side. Voltage of the AC power supply 1 and the reactor L _IN during this energy release is a shown polarity,
The capacitor C is charged with the sum of the two voltages. Therefore,
The voltage of the capacitor C is charged to a level equal to or higher than the peak value of the voltage of the AC power supply 1 (when the switches S _{1 to} S ₄ are composed of only diodes, the voltage of the capacitor C becomes the peak value of the AC power supply 1). It will not be higher. The magnitude of the current flowing through the reactor L _IN (Hence, the magnitude of the electromagnetic stored energy) can be adjusted by changing the time ratio of the on and off states of the transistors constituting the respective switches, reactor L _IN using this mechanism The waveform of the current flowing through is sinusoidal. The controller 30 creates a reference signal of the sine wave based on the sine wave voltage signal SG _E from the transformer PT _IN, so as to follow the input current signal SG _I obtained from the current transformer CT to the reference signal, i.e. current controlling the switches S ₁ to S ₄ so that the sinusoidal waveform.
The voltage EC of the capacitor C is fed back to control the amplitude of the reference signal so that the voltage EC is kept constant. In the inverter 4AC, give X, the AC voltage to the Y through the switching operation of the switch (S ₅ ~S ₆₎ constituting the bridge circuit and L _AC, the voltage waveform is shaped into a sine wave AC filter constituted by C _AC To supply power to the conversion load 7AC. Battery B when AC power supply 1 fails
Converter 7A converts the discharge power from the inverter 4AC into a converted load 7A.
Power is supplied to C. The conversion load 7AC receives power supply without interruption. 40A is a control device to obtain a signal for controlling the switches S ₅ to S ₆ of the inverter 4AC, the output voltage of the inverter is taken out as a signal SG _OUT via a transformer PT _OUT, which is a supply voltage to the converter load 7AC based A control signal is generated so as to be constant. In the period during which the AC power supply is interrupted, the UPS 34 only operates the inverter 4AC, and the input conversion unit 3 is closed.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed to improve the above-mentioned drawbacks, and an object of the present invention is to utilize an input conversion unit even when an AC power supply is interrupted to increase the power supply capability of a UPS. It is in. That is, an object of the present invention is to supply power to a commercial load by utilizing the input converter of the UPS as an inverter while supplying power to the original load of the UPS.

[0005]

In order to achieve the above object, the present invention provides an input converter connected to an AC power supply for supplying a commercial load and converting received power into DC power;
An output converter for converting the converted DC power back to AC, a DC electric energy source provided between the input converter and the output converter, and a device for supplying power to a conversion load from the output converter. The energy source is a battery, a solar cell, or a fuel cell, and the input conversion unit includes an AC filter including a capacitor and a reactor on its AC power supply side, and has a function of converting AC to DC and DC to AC in both directions. In addition, the control device of the input converter has a current control function A for making the waveform of the input current operated when converting from AC to DC a sine wave and controlling the level.
And the voltage control function B for controlling the level and the waveform of the output current to be operated in the case of conversion from DC to AC, and the waveform of the output current to be operated in the case of DC to AC conversion. And a current control function C for controlling a level. When the AC power supply is supplying power and receiving power, the input converter is converted from AC to DC by the current control function A. Operating, and when the AC power supply is supplying power and transmitting power, the input converter is operated to convert the electric power of the DC electric energy into AC by a current control function C to form a sine-shaped current into the AC. Output to the power supply side, and during a power failure of the AC power supply, the output of the DC electric energy source is switched by the voltage control function B to a part of the commercial load separated from the AC power supply by a switch. In which mode of the invention an uninterruptible power supply, characterized in that to the transmission is converted into electric power. Further, an input converter that connects to an AC power supply that supplies power to a commercial load and converts received power into DC power,
An output converter for reconverting the converted DC power to DC, a DC electric energy source is provided between the input converter and the output converter, and a device for supplying power to a conversion load from the output converter. The energy source is a battery, a solar cell, or a fuel cell, and the input conversion unit includes an AC filter including a capacitor and a reactor on its AC power supply side, and has a function of converting AC to DC and DC to AC in both directions. In addition, the control device of the input converter has a current control function A for making the waveform of the input current operated when converting from AC to DC a sine wave and controlling the level.
And the voltage control function B for controlling the level and the waveform of the output current to be operated in the case of conversion from DC to AC, and the waveform of the output current to be operated in the case of DC to AC conversion. And a current control function C for controlling a level. When the AC power supply is supplying power and receiving power, the input converter is converted from AC to DC by the current control function A. Operating, and when the AC power supply is supplying power and transmitting power, the input converter is operated to convert the electric power of the DC electric energy into AC by a current control function C to form a sine-shaped current into the AC. Output to the power supply side, and during a power failure of the AC power supply, the output of the DC electric energy source is switched by the voltage control function B to a part of the commercial load separated from the AC power supply by a switch. In which mode of the invention an uninterruptible power supply, characterized in that to the transmission is converted into electric power.

[0006]

According to the present invention, the input converter for converting AC to DC is provided with a function of converting DC to AC, so that an energy source of DC voltage provided in the apparatus should be provided in the event of an AC power failure. Can be converted to AC and supplied to the load on the AC power supply, and an uninterruptible power supply can be configured for the load on the AC power supply.

Next, the principle of the present invention will be described. FIG.
In the circuit configuration of the output converter unit and an input conversion unit 3 (inverter) try and configuration differs from compare 4AC is only the presence or absence of capacitor C _AC filter (presence of the transformer T is not essential). When a capacitor is inserted into the input terminal of the input conversion unit 3, both have the same configuration. In the control device, the current is controlled by the input conversion unit 30 while the inverter 40A is controlled by the voltage. Therefore, by simply inserting a filter capacitor C _IN into the input conversion unit and replacing the control device with a voltage control unit, the input conversion unit 3
Can also be used as an inverter. If the energy source provided by the UPS is sufficiently large, for example, if an energy source such as a fuel cell is provided instead of the battery B,
During the period when the AC power supply 1 is out of power, a long-time power supply can be performed from the UPS to the load through the input system even to the load that has been receiving power supply from the AC power supply. If the energy source of the UPS is a solar battery, while the energy from the solar battery during the day is sufficiently obtained, this energy is converted and supplied to the conversion load, and the power is supplied to the AC power source (commercial power system). At night, while there is no energy from the solar cells, UPS
Can convert the power received from the commercial power system again and supply it to the conversion load.

[0008]

Next, an embodiment of the present invention will be described. FIG.
Denotes an uninterruptible power supply of the present invention. In the figure, 1 is an AC power supply, 2 is a switch, 3 is an input converter, 4AC is an output converter (inverter), 40A and 430 are control devices,
5 is commercial load, 7AC is conversion load, B is battery, S
₁ to S ₈ switches, L _IN is the reactor, C is a capacitor, T is trans, PT _IN transformer, PT _OUT transformer, L _AC is the reactor, C _AC capacitor, SG _E is sinusoidal voltage signal, SG ₁ Indicates an input current signal.

[0009] When the AC power supply fails, the general UPS 34
In (see FIG. 7), only the inverter unit 4AC that converts the electric power of the battery B and supplies power to the load 7AC operates, and the input conversion unit 3 is in a non-operation state. In the present embodiment, the DC power of the battery B is converted into AC by using the input converter 3 during the interruption of the AC power supply, and is supplied to the commercial load 5 on the AC power supply side. When the capacitor C _IN is placed at the input end of the input conversion unit 3, the circuit configuration becomes symmetric about the capacitor C. That is, the configuration of the input conversion unit 3 is the same as that of the inverter unit 4AC. Therefore, the input conversion unit 3 can also function as an inverter. This is UPS34A. Next, the operation will be described. During a period in which the AC power supply 1 supplies power normally, the input converter 3 functions as a rectifier, and controls the power of the AC power supply 1 so that the current waveform becomes a sine wave. Receive power. When the AC power supply 1 fails, the input converter 3
Switch from current control to voltage control, and switch 2
Then, the AC power supply side is cut off to supply a constant voltage AC power to the commercial load 5. Conventional UPS for conversion load 7AC
Similarly to 34, power is supplied continuously during the period when the AC power is being supplied and also during the period when the power is stopped. When the demand of the commercial load is larger than the power capacity of the input converter 3 of the UPS, an important load can be selected from a large number of commercial loads by a switch, and power is supplied only to this. When an energy converter such as a solar cell or a fuel cell is used in place of the battery B, the power supply possible time of the UPS 34A during the blackout period of the AC power supply can be extended.

Next, a control device 40A for generating a signal for controlling the inverter 4AC will be described. FIG.
FIG. 3A shows a block configuration, and FIGS. 3A to 3E show the relationship between signals in each block. (A) shows the signal V _REF
And SG _OUT , (b) shows ST and SA,
(C) shows the SC, (d) shows an operation signal of the switch S _5, S _8, showing the (e) the operation signal of the switch S _6, S _7. The signal V _REF is a sine wave reference signal that determines the level and frequency of the output voltage of the inverter 4AC. A is an error amplifier that compares V _REF with a signal SG _OUT corresponding to the output voltage of the inverter 4AC and outputs a signal SA corresponding to the difference between the two. ST is a high frequency triangular waveform voltage signal. This frequency corresponds to the switches S _{5 to} S of the inverter 4AC
Determine the switching frequency of ₈ . COM compares the signals SA and ST by a comparator, and outputs a signal during a period when the absolute value of SA exceeds the absolute value of ST, and performs a pulse width control (hereinafter, referred to as PWM) of zero level during the other periods. Give a signal. SC is this PWM signal. D is a pulse distributor. PA _{5 to} PA ₈ amplify the signal from the distributor D to generate control signals to be supplied to the switches S _{5 to} S ₈ , respectively. PA ₅ between ～PA ₈ and D galvanically insulated use photocoupler for transmitting an optical signal. The positive pulse of SC is amplified and applied to switches S ₅ and S ₈ to turn it on. In addition, the negative pulse of SC is amplified and switches S ₆ and S
Give it to ₇ to turn it on. When the level of the signal SG _OUT falls, a control signal that increases the level is supplied to the switch S _5.
However in to S _8, also put out a control signal to reduce this if rises the level, i.e. the feedback control to maintain the output voltage of the inverter 4AC constant.

Next, a control device 43 for controlling the input converter 3
0 will be described. FIG. 4 shows a block configuration. FIG.
(A)-(f) show the relationship between each signal. (A) shows a signal E _S, (b) shows the signal SA _10, (c) shows a signal SG _E, (d) shows the signal SG _EO, (e) shows a signal SG _I, (f) shows a signal SA _20. The control device 430 includes a current control unit CC and a voltage control unit VC, of which the voltage control unit VC has the same configuration as that of FIG. The current control unit CC will be described. The voltage E _C of the capacitor C, which is the output DC voltage of the input converter 3, and the DC reference voltage E
Sell signals SA ₁₀ compares amplify and _REF error amplifier A _10. If E _REF > E _C , SA ₁₀ is at a level higher than E _REF , and if E _REF <E _C , SA ₁₀ is at a level lower than E _REF . Being equal both signals SA ₁₀ is equal to E _REF. The voltage of the AC power source 1, used as a reference voltage signal SG _E sine wave synchronized thereto. This signal SG
_E (I × sinωt) and signal SA ₁₀ (signal level is E _S
Obtaining a sine wave signal SG _EO (E _S × sinωt) having the amplitude corresponding to the SA ₁₀ is input to the multiplier M the to).
Plus the signal SG ₁ corresponding to the input current and signal SG _EO to the error amplifier A _20, to obtain a signal SA ₂₀ corresponding to the difference.
Comparator and signal SA ₂₀ and the triangular wave signal ST COM ₁₀
Obtaining a PWM signal SC ₁₀ in addition to. The signal SG _E (referred to as sinωt) for forming the reference of the input current shown in FIG. 5 is used for controlling the input current of the input converter 3, and is used when the input converter is operated as an inverter while the AC power is supplied. SG _E polarity reversal (i.e., as -Sinomegati) is not varied to control the output current. From the viewpoint of the UPS, (voltage × current) is positive at the time of input, and negative at the time of output.
Signal of the voltage to be fed back to the voltage control unit VC is the voltage of the input portion of the input conversion unit 3, i.e., using the SG _E. Power failure to have time to switch 2 signal SG _E When (FIG. 1) to turn off becomes a signal corresponding to an AC voltage of a sine wave constant-voltage constant-frequency input transducer is output as an inverter. Electronic switch DS is passed through a signal SC ₁₀ of current in the period in which the AC power supply 1 is powered, the period during which the power failure through a signal SC ₁₁ of the voltage. The pulse distributor D receives the signal SC ₁₀ or S
Distributes receiving C _11, an insulating amplifier PA ₁ ~PA
_{In step 4} , a signal for controlling the switches S _{1 to} S ₄ to be turned on / off is obtained.

FIG. 6 shows a second embodiment of the present invention. FIG.
When a DC output conversion circuit 4DC (hereinafter referred to as a DC-DC converter) is combined in place of the AC output conversion unit, that is, the inverter 4AC, a DC voltage is obtained. The primary winding of the transformer T is connected to the AC terminals X and Y of the bridge circuit, the output voltage of the secondary winding is rectified by the bridge rectifier circuit Q _REC , and the ripple voltage is further passed through the smoothing filters L _DC and C _DC. To obtain a DC voltage with less power. This is supplied to a DC conversion load 7DC. If the conversion frequency of the switches S _{5 to} S ₈ constituting the bridge circuit is increased to a high frequency, for example, 20 kHz or more, the transformer T, the smoothing filters L _DC and C _DC can be significantly reduced in size, and
Noise can be eliminated. The input converter is the same as in the example of FIG.

When a solar cell is used as an electric energy source, for example, the input converter functions as an inverter even during the supply of the AC power, and if there is enough energy in the solar cell, this is output to the input side. Can be done. In this case, the input converter functions in the state of current control. Use dashed signals shown the polarity of the signal SG _E making reference signal of the input current in FIG. 5 (c) (-sinωt). The output current is controlled accordingly (the input current is controlled by the signal indicated by the solid line). In the embodiments described so far, both the input conversion unit and the output conversion unit have been described using a single-phase circuit, but a three-phase circuit can be handled similarly as is generally used. Also, a bipolar transistor has been described as an example of a semiconductor switch, but other power MOS / F
ET, IGBT (Insulated Gate Bipolar Transistor)
) Can be used as well.

[0014]

The input converter constituting the uninterruptible power supply is not only used for the so-called rectification function, but also supplies a constant-voltage AC power to the input-side commercial load as an inverter in the event of a power failure. New concept of a power supply unit, which is used for power sales by injecting alternating current with a high-quality current waveform during interconnection of power supply, and a technology that realizes this very economically, that is, large cost and volume A technology is disclosed in which an input conversion unit is commonly used, which can be realized at low cost and has three functions to be selectively used by a small control device. This has a remarkable effect in the following uses. Part 1: Example of power supply to computer system In order to continue operation of the computer, power supply without interruption is a necessary condition. 100 of the power supplied to this computer
Nearly percent is converted to heat energy and dissipated into the computer room, raising room temperature. On the other hand, it is a necessary condition for the computer to maintain the temperature of the operating environment close to 20 ° C., and therefore, the air conditioning equipment is indispensable in the computer room.
Generally, this air conditioner is directly operated with a commercial power supply from the viewpoint of economy. For this reason, in the event of a power outage, a general uninterruptible power supply only supplies power to the computer itself, so the air conditioning equipment stops, and as a result, the temperature of the computer room rises, and the computer does not stop operating. Will not get. When the uninterruptible power supply of the present invention is applied to these computer systems, at the time of a power failure, the operation mode is switched from the input conversion unit to the inverter operation mode to supply power to the air conditioning equipment (restart is easy even if the power supply is momentarily interrupted, and there is no problem). Therefore, the room temperature can be controlled while power is continuously supplied from the output converter to the computer as the conversion load. You can run the computer while DC electrical energy is available. As long as the DC electric energy source can supply power for a long time, such as a large capacity battery or a solar cell, as in the following example, the effect of the present invention becomes extremely remarkable. Part 2: An example of an operation system linked to a commercial AC power supply As in the case where the electric energy source is a solar cell, during the daytime, while the solar energy is sufficiently obtained, the power is supplied to the conversion load 7 and the surplus energy is supplied. Can be converted into AC by the input converter, and the sine wave current can be transmitted to the commercial power supply system side. The apparatus of the present invention can be operated with a commercial power supply to sell power, which is economical. In this case, the load to be supplied with power is not limited to the commercial load 5, but may be a load (not shown in FIG. 1) on the external commercial power supply via the switch 2. Thus, at the peak of the commercial power demand (mostly during the time period from 10:00 to 14:00)
The power transmitted from the present application contributes to the reduction of the burden on the commercial power supply (the capacity of the commercial power supply corresponds to the peak value and the load is heavy. If the number of power sources increases, it helps to reduce the peak value of the power demand, which has the effect of reducing the burden of capital investment for commercial power sources. Also, a large-capacity facility is provided as a battery, and the battery is charged with power at a low unit price at night (operated in the operation mode of the rectifier). If the power is transmitted (operated in the interconnected operation mode) and sold to the commercial power source, there is an income equivalent to the difference in the power rate, and the economic effect of reducing the amount of power received in the contract with the power company can be obtained. . From the viewpoint of the commercial power supply side, the power is used when the nighttime power demand is small, and the power is transmitted when the daytime power demand is high, which contributes to the leveling of the power demand. Usage form. In the present invention, by utilizing one set of input converters, the system can be operated in a system combining the above two examples of the system, so that the configuration of the power supply system is simplified and extremely high economical effects are exhibited. .

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention.

FIG. 2 shows a configuration of an inverter control device.

3 (a) to 3 (e) show waveforms at various parts in FIG. 2;

FIG. 4 shows a configuration of a control device of an input conversion unit.

5 (a) to 5 (f) show waveforms at various parts in FIG.

FIG. 6 shows a second embodiment of the present invention.

FIG. 7 shows a conventional AC uninterruptible power supply.

[Explanation of symbols]

1 AC power supply 2 switch 3 the input conversion unit 4AC output conversion unit 40A controller 430 the control unit 5 commercial load 7AC conversion Load B Battery S ₁ to S ₈ switches L _IN reactor C condenser T trans PT _IN transformer PT _OUT transformer L _AC reactors C _AC capacitor SG _E Sine wave voltage signal SG ₁ input current signal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-111237 (JP, A) JP-A-2-2855941 (JP, A) JP-A-62-254632 (JP, A) JP-A-62-254 230332 (JP, A) JP-A-64-39239 (JP, A) JP-A-3-36930 (JP, A) JP-A-61-98347 (JP, U) JP-A-61-185236 (JP, U) 57-17231 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02J 9/06 H02M 7/219, 7/48

Claims (2)

(57) [Claims] 1. An input converter connected to an AC power supply that supplies power to a commercial load and converting received power into DC power.
An output converter for converting the converted DC power back to AC, a DC electric energy source provided between the input converter and the output converter, and a device for supplying power to a conversion load from the output converter. The energy source is a battery, a solar cell, or a fuel cell. The input converter includes an AC filter including a capacitor and a reactor on the AC power supply side, and has a function of converting AC to DC and DC to AC in both directions. The control device of the input conversion unit has a current control function A for making the waveform of the input current operated in the case of converting from AC to DC, and controlling the level, and operating in the case of converting from DC to AC. The output voltage waveform to be sinusoidal,
And a voltage control function B for controlling the level and a current control function C for controlling the level by making the waveform of the output current operated in the case of conversion from DC to AC into a sine wave shape, and controlling the level. When the AC power supply is supplying power and receiving power, the input conversion unit is operated to perform conversion from AC to DC by the current control function A. When the AC power supply is supplying power and transmitting power, the input conversion unit is used. Is operated by converting the electric power of the DC electric energy into AC by a current control function C to output a current shaped into a sine wave to the AC power supply side, and is disconnected from the AC power supply by a switch during a power failure of the AC power supply. An uninterruptible power supply device, characterized in that the output of the DC electric energy source is converted into AC power and transmitted to some commercial loads by a voltage control function B. 2. An input converter connected to an AC power supply for supplying power to a commercial load and converting received power into DC power;
An output converter for reconverting the converted DC power to DC, a DC electric energy source provided between the input converter and the output converter, and a device for supplying power to a conversion load from the output converter. The energy source is a battery, a solar cell, or a fuel cell. The input converter includes an AC filter including a capacitor and a reactor on the AC power supply side, and has a function of converting AC to DC and DC to AC in both directions. The control device of the input conversion unit has a current control function A for making the waveform of the input current operated in the case of converting from AC to DC, and controlling the level, and operating in the case of converting from DC to AC. The output voltage waveform to be sinusoidal,
And a voltage control function B for controlling the level and a current control function C for controlling the level by making the waveform of the output current operated in the case of conversion from DC to AC into a sine wave shape, and controlling the level. When the AC power supply is supplying power and receiving power, the input conversion unit is operated to perform conversion from AC to DC by the current control function A. When the AC power supply is supplying power and transmitting power, the input conversion unit is used. Is operated by converting the electric power of the DC electric energy into AC by a current control function C to output a current shaped into a sine wave to the AC power supply side, and is disconnected from the AC power supply by a switch during a power failure of the AC power supply. An uninterruptible power supply device, characterized in that the output of the DC electric energy source is converted into AC power and transmitted to some commercial loads by a voltage control function B.