JP3620551B2 - Uninterruptible power system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an uninterruptible power supply, and more specifically, relates to an uninterruptible power supply having an uninterruptible line including a booster circuit that boosts DC power from a storage battery and supplies it to an inverter when a commercial power supply fails. Is.
[0002]
[Prior art]
The uninterruptible power supply always supplies AC power from a commercial power source directly to a load via a direct transmission line, and at the time of a power outage, the uninterruptible power supply unit converts the DC power from a storage battery into AC power via the uninterruptible line. It is intended to be supplied to the load in order to prevent a load trouble caused by a power failure.
[0003]
The storage battery used in such an uninterruptible power supply must be designed so that the end-of-discharge voltage is 170 V or higher when trying to obtain 100 V for the output of the uninterruptible line, and many storage batteries are connected in series. Instead of this, a booster circuit that boosts the DC voltage of the storage battery to reduce the cost and weight has been widely used.
[0004]
The conventional uninterruptible power supply device provided with the booster circuit as shown in FIG. 3 is a charger 2 that receives AC power from the commercial power source 1 and outputs the charging power of the storage battery, and this charger 2. Storage battery 3 charged with charging power from the battery, a booster circuit 4 that boosts DC power from the battery 3, an inverter 5 that converts DC power boosted by the booster circuit 4 into AC power, and an AC from the inverter 5 There is an uninterruptible line 10 comprising a filter 6 for waveform shaping of the output and a direct transmission line 20 for directly outputting AC power from the commercial power supply 1, and the uninterruptible line 10 and the direct transmission line 20 are switched by a changeover switch 30. It can be switched between each other.
[0005]
The booster circuit 4 includes a series connection circuit of a choke coil 41 and a switching element 42 connected between terminals of the storage battery 3, a diode 43, a first capacitor 44-1 and a first capacitor 44-1 connected in parallel to the switching element 42. The inverter 5 includes a connection point between the diode 43 and the first capacitor 44-1, and a connection point between the second capacitor 44-2 and the switching element 42. The first switching element 51-1 and the second switching element 51-2 are connected in series, and the filter 6 includes the first switching element 51-1 and the second switching element 51-2. And a connection point between the first capacitor 44-1 and the second capacitor 44-2. I filter reactor 61 comprises a serial connection circuit of the filter capacitor 62.
[0006]
Next, the operation of the above conventional uninterruptible power supply will be described with reference to FIG.
[0007]
As shown in FIG. 4, the switching element 42 of the booster circuit 4 is turned on at a frequency higher than the frequency of the commercial power supply 1 and with a pulse width such that the output voltage of the booster circuit 4 becomes an appropriate value as the input voltage of the inverter 5. The first switching element 51-1 and the second switching element 51-2 of the inverter 5 are turned off at a frequency higher than the frequency of the commercial power source 1 for each cycle of the commercial power source 1 and with a pulse width proportional to the peak value. By alternately turning on and off, a sine wave having the same frequency as that of the commercial power supply 1 is output between the terminals of the filter capacitor 62 of the filter 6.
[0008]
That is, when the switching element 42 of the booster circuit 4 is on, current flows through the path {circle around (1)} of the storage battery 3 → the choke coil 41 → the switching element 42 → the storage battery 3 to accumulate energy in the choke coil 41. When the switching element 42 is off, a current flows through the path (2) of the storage battery 3 → the choke coil 41 → the diode 43 → the first capacitor 44-1 → the second capacitor 44-2 → the storage battery 3 and the first capacitor 44 −1, the second capacitor 44-2 is charged.
[0009]
When the first switching element 51-1 of the inverter 5 is on, the second switching element 51-2 is off, and the on-duty of the first switching element 51-1 is 50% or more, the path (1), 2), current flows through the first capacitor 44-1, the first switching element 51-1, the filter reactor 61, the filter capacitor 62, and the first capacitor 44-1. When 44-1 is discharged, the first switching element 51-1 of the inverter 5 is turned off, and the second switching element 51-2 is turned on, a current flows through the paths (1) and (2), and a filter reactor. 61 → filter capacitor 62 → second capacitor 44-2 → parasitic diode of second switching element 51-2 → filter react 61 becomes the path ▲ 4 ▼ current flows in the positive half cycle is outputted between the terminals of the filter capacitor 62.
[0010]
Further, when the first switching element 51-1 of the inverter 5 is off, the second switching element 51-2 is on, and the on-duty of the first switching element 51-1 is 50% or less, the path (1), ▲ 2), current flows through the second capacitor 44-2 → filter capacitor 62 → filter reactor 61 → second switching element 51-2 → second capacitor 44-2, so that current flows through the second capacitor 44-2. When 44-2 is discharged, the first switching element 51-1 of the inverter 5 is turned on, and the second switching element 51-2 is turned off, a current flows through the paths (1) and (2) and a filter reactor. 61 → parasitic diode of first switching element 51-1 → first capacitor 44-1 → filter capacitor 62 → filter reactor Negative half cycle is outputted between the terminals of the filter capacitor 62 current flows through the 1 consisting path ▲ 6 ▼.
[0011]
[Problems to be solved by the invention]
With the above-described operation, the DC voltage of the storage battery 3 can be boosted and supplied to the inverter 5, but when trying to obtain 100 V for the output of the uninterruptible line, the first capacitor 44-1 and the second capacitor 44-2 A DC voltage of about 340 V is applied to the series connection circuit with the voltage of the switching element 42 of the booster circuit 4 and the withstand voltages of the first switching element 51-1 and the second switching element 51-2 of the inverter 5. There was a problem that it had to be 400V class or higher, thereby increasing the cost.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a charger that receives AC power from a commercial power source and outputs charging power of the storage battery, a storage battery that is charged by the charging power from the charger, and DC power from the storage battery. An uninterruptible line comprising a booster circuit for boosting the voltage, an inverter for converting the DC power boosted by the booster circuit to AC power, and a filter for shaping the AC output from the inverter, and the AC power from the commercial power supply directly In the uninterruptible power supply apparatus having a direct transmission line for outputting and a changeover switch for switching the uninterruptible line and the direct transmission line to each other, the booster circuit includes two sets of switching elements connected between terminals of the storage battery. A series connection circuit, and first and second series connection points connected to a series connection point of the first set of switching elements. A series connection circuit of capacitors, and a series connection circuit of first and second diodes, the series connection point of which is connected to the series connection point of the second set of switching elements, and the first and second capacitors. And a series connection circuit of the first and second diodes are connected in parallel, and the inverter includes a series connection circuit of the first and second capacitors and the first and second diodes. The filter comprises a series connection circuit of first and second switching elements connected in parallel with a series connection circuit, and the filter includes a series connection point of the first and second switching elements and the first and second diodes. It is characterized by comprising a series connection circuit of a filter reactor and a filter capacitor connected between the series connection points.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments.
[0014]
FIG. 1 is a circuit diagram showing an embodiment of the uninterruptible power supply apparatus according to the present invention, and parts having the same functions as those in FIG.
[0015]
The feature of the present invention is that, as shown in FIG. 1, the booster circuit 4 is connected to the series connection circuit 42A of the first set of switching elements 42A-1 and 42A-2 connected between the terminals of the storage battery 3 and the second set. The series connection circuit 42B of the switching elements 42B-1 and 42B-2, and the first and second capacitors 44 whose series connection point is connected to the series connection point of the first set of switching elements 42A-1 and 42A-2. -1, 44-2 series connection circuit, and first and second diodes 43-1 and 43 whose series connection point is connected to the series connection point of the second set of switching elements 42B-1 and 42B-2. -2 series connection circuit, and the series connection circuit of the first and second capacitors 44-1 and 44-2 and the first and second diodes 43-1 and 43-2. Are connected in parallel. Thus, the inverter 5 is connected in parallel with the series connection circuit of the first and second capacitors 44-1 and 44-2 and the series connection circuit of the first and second diodes 43-1 and 43-2. The first and second switching elements are connected in series, and the filter 6 is connected to the first and second switching elements in series and the first and second diodes 43-1 and 43-. A series connection circuit of a filter reactor 61 and a filter capacitor 62 connected between two series connection points.
[0016]
Next, the operation of the uninterruptible power supply of the present invention will be described with reference to FIG.
[0017]
As shown in FIG. 2, the first set of switching elements 42 </ b> A- 1 and 42 </ b> A- 2 and the second set of switching elements 42 </ b> B- 1 and 42 </ b> B- 2 of the booster circuit 4 have the same frequency as that of the commercial power supply 1. The switching elements 42A-1, 42B-2 and the switching elements 42A-2, 42B-1 are simultaneously turned on and off, respectively, and the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are commercial power sources 1 When the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, the inverters are alternately turned on and off at a frequency higher than that frequency every half cycle and with a pulse width proportional to the peak value. The first switching element 51-1 is turned on and off, the second switching element 51-2 is turned off, and the filter capacitor 62 of the filter 6 is turned on. When a positive half cycle is output between the terminals and the switching elements 42A-2 and 42B-1 of the booster circuit 4 are turned on, the first switching element 51-1 of the inverter 5 is turned off, and the second switching element 51-2 Is turned on and off to output a negative half cycle between the terminals of the filter capacitor 62 of the filter 6.
[0018]
That is, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, the switching elements 42A-2 and 42B-1 are turned off, the first switching element 51-1 of the inverter 5 is turned on, and the second switching element When 51-2 is off, the path (1) of the storage battery 3 → the switching element 42A-1 → the second capacitor 44-2 → the second diode 43-2 → the switching element 42B-2 → the storage battery 3 and the first capacitor 44-1 → first switching element 51-1 → filter reactor 61 → filter capacitor 62 → switching element 42B-2 → storage battery 3 → switching element 42A-1 → path (2) consisting of the first capacitor 44-1 The first capacitor 44-1 is discharged, the second capacitor 44-2 is charged, and the filter reactor 61 is charged. The sum of the voltage between the terminals of the first capacitor 44-1 and the voltage of the storage battery 3 is applied to the series connection circuit with the filter capacitor 62, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, and the switching element 42A- 2, 42B-1 is turned off, and when the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are off, the path (1) and the filter reactor 61 → filter capacitor 62 → A current flows through the path (3) of the switching element 42B-2 → the storage battery 3 → the switching element 42A-1 → the second capacitor 44-2 → the parasitic diode of the second switching element 51-2 → the filter reactor 61 and the filter reactor 61 The voltage applied to the series connection circuit of the filter capacitor 62 becomes 0, and the first switch When the ON / OFF ratio of the switching element 51-1 and the second switching element 51-2 is controlled to be proportional to the peak value of the voltage of the commercial power supply 1, a positive half cycle is output between the terminals of the filter capacitor 62. Can do.
[0019]
Further, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned off, the switching elements 42A-2 and 42B-1 are turned on, the first switching 51-1 of the inverter 5 is turned off, and the second switching element 51 is turned on. -2 is on, the path (4) of the storage battery 3 → the switching element 42B-1 → the first diode 43-1 → the first capacitor 44-1 → the switching element 42A-2 → the storage battery 3 and the second capacitor 44 −2 → switching element 42A-2 → storage battery 3 → switching element 42B-1 → filter capacitor 62 → filter reactor 61 → second switching element 51-2 → second capacitor 44-2, current flows through the path (5). The second capacitor 44-2 is discharged, the first capacitor 44-1 is charged, and the filter reactor 61 and the filter are filled. The sum of the voltage between the terminals of the second capacitor 44-2 and the voltage of the storage battery 3 is applied to the series connection circuit with the capacitor 62, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned off, and the switching element 42A-2 , 42B-1 are turned on, and when the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are off, the path (4) and the filter reactor 61 → the first switching element 51 -1 parasitic diode → first capacitor 44-1 → switching element 42 </ b> A- 2 → storage battery 3 → switching element 42 </ b> B- 1 → filter capacitor 62, a current flows to filter reactor 61 and filter capacitor 62. The voltage applied to the series connection circuit is 0, and the first switching element 51-1, the second switching element On the element 51-2 and controls to proportional off ratio peak value of the voltage of the commercial power source 1, it is possible to output a negative half-cycle between the terminals of the filter capacitor 62.
[0020]
When a positive half cycle is output between the terminals of the filter capacitor 62 by the above-described operation, the potential on the negative electrode side of the first capacitor 44-1 rises to the DC voltage of the storage battery 3 by turning on the switching element 42A-1. Therefore, when a voltage that is twice the DC voltage of the storage battery 3 is applied to the second switching element 51-2 and a negative half cycle is output between the terminals of the filter capacitor 62, the switching element 42B-1 Since the DC voltage of the storage battery 3 is added to the potential on the positive electrode side of the second capacitor 44-2 when turned on, a voltage twice as high as the DC voltage of the storage battery 3 is applied to the first switching element 51-1.
[0021]
Therefore, when trying to obtain 100V in the output of the uninterruptible line, the DC voltage of the storage battery 3 is applied so that a DC voltage of about 170V is applied to the series connection circuit of the first capacitor 44-1 and the second capacitor 44-2. The withstand voltage of the switching elements 42A-1, 42A-2, 42B-1, 42B-2 of the booster circuit 4 and the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are also 200V. It is possible to respond with the thing of the grade.
[0022]
【The invention's effect】
As described above, the present invention can reduce the DC voltage of the storage battery of the uninterruptible power supply, and does not need to use a high withstand voltage switching element used in the booster circuit and the inverter. The cost and weight of the device can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an uninterruptible power supply according to the present invention.
FIG. 2 is an operation waveform diagram of each part of the uninterruptible power supply according to the present invention.
FIG. 3 is a circuit diagram of a conventional uninterruptible power supply.
FIG. 4 is an operation waveform diagram of each part of a conventional uninterruptible power supply.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Charger 3 Storage battery 4 Booster circuit 5 Inverter 6 Filter 10 Uninterruptible line 20 Direct transmission line 30 Changeover switch

Claims (1)

A charger that receives AC power from a commercial power source and outputs the charging power of the storage battery, a storage battery that is charged by the charging power from the charger, a booster circuit that boosts DC power from the storage battery, and a booster that boosts the voltage An uninterruptible line composed of an inverter that converts the DC power into AC power and a filter that shapes the AC output from the inverter, and a direct transmission line that directly outputs the AC power from the commercial power source. in the uninterruptible power supply having a switching switch for switching the power failure line and direct line with each other, said booster circuit being connected between the terminals of the storage battery, on the frequency of the commercial power source, first and second sets to off The switching element series connection circuit and the series connection point are connected to the series connection point of the first set of switching elements. First, a series connection circuit of the second capacitor, the first consists of a series circuit of a second diode series connection point is connected to a series connection point of the second set of switching elements, and said A series connection circuit of first and second capacitors and a series connection circuit of the first and second diodes are connected in parallel, and the inverter includes the series connection circuit of the first and second capacitors and the first connection circuit. 1. A series connection circuit of first and second switching elements connected in parallel with a series connection circuit of second diodes and turned on and off at a frequency higher than the frequency of a commercial power supply. A series connection circuit of a filter reactor and a filter capacitor connected between the series connection point of the second switching element and the series connection point of the first and second diodes. Uninterruptible power supply, characterized in that.

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