JP2002354679A - Power conversion device, and power supply system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device, which enables supplying power of high quality without blackout to apparatuses such as information processing devices, or the like, for which stabilization of power supply is always required; which effectively utilizes as much as possible energies obtainable from DC power supplies such as fuel cells, secondary batteries, solar cells, wind power generation means, or the like; and further whose circuit structure to control those is simple; and an electric power supply system using it. SOLUTION: In the power conversion device 1, comprising a first AC conversion part 4 which has a first bridge circuit 3 comprising a plurality of semiconductor switching elements; and a second AC conversion part 6 which has a second bridge circuit 5 comprising a plurality of semiconductor switching elements, the AC power converted in the first Ac conversion part 4 is subjected to grid-connected operation with a commercial power supply system, and the AC power converted in the second AC conversion part 6 is outputted to an exclusive load 8 so that a stable power source supply to the exclusive load 8 can be executed independent of the condition of the commercial power supply system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell,
The present invention relates to a power converter that converts DC power from a DC power supply such as a secondary battery (storage battery), a solar battery, and a wind power generator into AC power, and a power supply system using the same.

[0002]

2. Description of the Related Art As shown in FIG. 5, in a power supply system 15, a fuel cell, a secondary battery, a solar cell,
DC power supplied from a DC power supply 16 such as a wind power generator is converted into AC power by a power converter 21,
It is connected to the commercial power supply 7 and is configured to supply power to a load 8 connected to the commercial power supply 7.

Here, as shown in FIG. 6, a power conversion device 21 includes a DC voltage conversion circuit 17 for stabilizing a DC voltage obtained from a DC power supply 16 and an inverter circuit 18 for converting DC power to AC power. Inverter circuit 1
Numeral 8 has a bridge circuit 19 composed of a plurality of switching elements and a filter unit 20. After the bridge circuit 19 converts DC into AC, the filter 20 converts the output waveform into a commercial AC waveform. .

In FIG. 6, AC power is supplied to the commercial power supply 7 from the power supply system 15. However, when a power failure or momentary interruption occurs on the commercial power supply 7 side, the equipment on the power company side is caused by reverse power flow. Automatically stop output so as not to damage it. For this reason, if a power failure or momentary interruption occurs on the commercial power supply 7 side, the load 8 cannot receive not only the power supply from the power company but also the power supply from the power supply system 15, and the load 8 stops.

[0005] In recent years, with the progress and spread of multimedia, the use ratio of personal computers and information terminals has been increasing, and it has become indispensable for the processing and transmission of information in society including ordinary households. Has become.

[0006] However, many of them require a commercial power supply to operate, and a stable power supply without a power failure is demanded for an apparatus for performing such information processing. Further, when a power supply of a device having a large capacity storage device such as a personal computer is cut off due to an abnormality such as a power failure or a momentary interruption, not only the device but also valuable data may be fatally damaged.

Conventionally, an uninterruptible power supply (UPS) that generates an AC power supply using a pre-charged storage battery as a power supply when a commercial power supply fails has been used as a power compensation device.

Further, as disclosed in Japanese Patent Application No. 10-263520, power is supplied to a load by switching from grid-connected operation to self-sustained operation in a photovoltaic power generation unit when a power supply on the commercial power supply side fails. There has been proposed a configuration for preventing instantaneous interruption in the above.

A power supply source other than the commercial power supply, such as the above-mentioned uninterruptible power supply, has a power supply source, and can compensate for power supply to the load even if a power failure or instantaneous interruption occurs on the commercial power supply side. Providing the device is effective for an information processing device such as a personal computer in which shutting off the power supply can cause fatal damage. However, these are generally expensive, and are only loads that consume power except for power compensation at the time of power failure.

Therefore, at the time of a power failure on the commercial power supply side, a photovoltaic power generation system or the like that can switch from grid-connected operation to independent operation is used. It is conceivable to supply power to equipment or sell power to a power company.

[0011] However, since the operation is switched after detecting a power failure, it is difficult to supply power without complete instantaneous interruption, and an abnormal voltage and an abnormal waveform generated due to an external surge or the like when the system is normal. There is a problem that intrusion cannot be prevented. In this case,
The same applies when a DC power supply such as a solar cell is combined with a power storage means such as a battery.

Further, there is a problem that the power cannot be compensated for a load when power cannot be generated, for example, in a solar power generation system at night or in a system using wind power generation when there is no wind.

The present invention has been devised in view of the above-mentioned conventional problems, and provides a high-quality power supply without power failure to equipment such as an information processing apparatus in which power supply stabilization is always desired. And a power conversion device having a simple configuration of a circuit for controlling and using the energy obtained from a DC power source such as a fuel cell, a secondary battery, a solar cell, and a wind power generation device as effectively as possible. It is an object of the present invention to provide a power supply system using a power supply.

[0014]

To solve the above-mentioned problems, a power converter according to the present invention is connected between a commercial power supply and a DC power supply, and converts DC of the DC power supply into AC. And a first DC / AC converter having a first bridge circuit configured of a plurality of semiconductor switching elements and converting DC to AC, connected in parallel to the first DC / AC converter, and A second DC / AC converter having a second bridge circuit for converting DC to AC, wherein the first DC / AC converter is system-connected to a commercial power supply, and the second DC / AC converter is It is characterized by being connected to a dedicated load. As a result, stable high-quality power supply to the dedicated load can be performed without depending on the state of the system on the commercial power supply side.

Further, the output of the first DC / AC converter is controlled according to the output of the second DC / AC converter. As a result, the output to the dedicated load is prioritized, stable power supply is possible, and surplus power is reversely flowed to the commercial power supply system, making it possible to effectively use energy obtained from a solar cell or the like.

A power converter connected between a commercial power supply and a DC power supply for converting the DC of the DC power supply into an alternating current, wherein the power conversion apparatus converts the DC power from the DC power supply through a rectifier. And supplying power to the second AC converter from the power storage means. As a result, even when the solar cell, which is a DC power supply, does not generate power at night, when the weather is bad and sufficient energy cannot be obtained, when the wind power from the wind power generation means is not sufficient, or when the commercial power supply system fails, the dedicated load is applied. Enables stable power supply.

In addition, a rectifier or a charger is connected between the commercial power supply and the first DC / AC converter, and power is supplied from the rectifier or the charger to the second DC / AC converter. It is characterized by the following. As a result, even if the DC power supply fails or the voltage of the power storage means does not recover sufficiently when the operation is stopped, power supply to the dedicated load is not interrupted.

The power supply system of the present invention is connected between a DC power supply and a commercial power supply.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a power converter according to the present invention and a power supply system using the same will be described in detail with reference to the drawings schematically shown. It is to be noted that the same components as described above are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows a power converter D1 for converting the DC power of one or more DC power sources 2 such as a fuel cell, a solar cell, a wind power generation means, etc. into AC power, and a power supply system S1 equipped with them. The schematic circuit diagram of FIG.

The power conversion device D1 of the present invention comprises a commercial power supply 7
A first DC / AC converter 4 connected between the DC / DC power supply 2 and having a first bridge circuit 3 composed of a plurality of semiconductor switching elements and converting DC to AC; And a second DC / AC converter 6 having a second bridge circuit 5 that is connected and includes a plurality of semiconductor switching elements and converts DC to AC.
The DC / AC converter 4 is designed to be able to be connected to the commercial power source 7 and connected to the grid, and the second DC / AC converter 6 is required to always have a stable power supply, such as a measuring device using a personal computer. Dedicated load 8 that will cause damage not only to data but also to the equipment itself if stopped for example
Power supply.

Here, the power applied to the power converter D1 is DC power such as power generated by a fuel cell, a secondary battery, a solar cell, a wind power generation means and the like, and the first power connected in parallel.
The DC / AC converter 4 and the second DC / AC converter 6 are connected.

Each of the first bridge circuit and the second bridge circuit is composed of a bridge circuit such as a half bridge circuit or a full bridge circuit.

A first DC / AC converter 4 having a first bridge circuit 3 and a second DC / AC converter 6 having a second bridge circuit 5 convert DC into AC in each bridge circuit, and generate an AC waveform. It converts to higher quality AC by a circuit that adjusts the frequency, the link, and the link timing. Also,
The first bridge circuit 3 and the second bridge circuit 5 need not have the same capacity or the same system, and may select a system that can increase the efficiency as far as the rating of the semiconductor switching element allows.

For example, when used in ordinary households and small-scale measurement systems, the DC power supply is about 3 to 4 kW, and the capacity required for information equipment such as a personal computer considered as the dedicated load 8 is about several hundred W. Becomes If the capacity of the dedicated load 8 is small, an IGBT (Insulated Gate Bipolar T
ransistor: Insulated gate bipolar transistor) and power MOSFET (Metal Oxide Semiconductor Field-
Adopting a bridge circuit using a semiconductor switching element such as an Effect Transistor) can provide a highly efficient AC converter.

For example, in a residential solar power generation system, when the personal computer that records the power generation status is the dedicated load 8, the output capacity of the first DC / AC converter 4 is large and the output capacity of the second DC / AC converter 6 is large. If the output capacity can be small, the first bridge circuit 3 of the first DC / AC converter 4
An IGBT which preferably operates as a switching element for a large current is provided in the second bridge circuit 5 of the second DC / AC converter 6, and a power M which preferably operates as a switching element.
It is desirable to use OSFETs. Further, with such a configuration, it is possible to provide a power conversion device with a small conversion loss because the loss inside the switching element is commensurate with the power used.

On the other hand, when considering the use in a large-scale observation system using a large number of measuring instruments in a research institution or the like, for example, since the power consumption of the dedicated load 8 is large, the first power connected to the commercial power source 7 is used. A bridge circuit having an output capacity equal to or larger than that of the first bridge circuit 3 of the DC / AC converter 4 should be provided.

Next, a description will be given of a power supply system S2 provided with a power converter D2 shown in FIG. 2, which is another embodiment.

The power conversion device D2 shown in FIG. 2 is different from the power conversion device D1 shown in FIG. 1 in that an output detecting means 9 which comprises a magnetic current detector and detects an output state from the first DC / AC converter 4 is used. (2) An output detection unit 10 provided between the filter unit 20 of the DC / AC conversion unit 4 and the commercial power supply 7 and having the same configuration and operation as the output detection unit 9 is connected to the filter unit 20 of the second DC / AC conversion unit 6. And between the commercial power supply 7 and
Further, an input detecting means 11 comprising a magnetic current detector for detecting an input state from the DC power supply 2 is provided between the DC power supply 2 and the first and second DC / AC converters 4 and 6. Things. In particular, the power supply system S2 uses the fuel cell as the DC power supply 2. Here, the fuel cell is used because it is suitable as a power generation means for supplying stable DC power.

In the first DC / AC converter 4 having the first bridge circuit 3 of the power converter D2, the DC power obtained by the DC power source 2 as a fuel cell is converted into a sine-wave commercial AC waveform. A system interconnection operation with the power supply system 7 is performed. A second DC / AC converter 6 having a second bridge circuit 5
, The DC power obtained by the DC power supply 2 is converted into a sine-wave commercial AC waveform by a
Output to

The first DC / AC converter 4 in this embodiment
And the bridge circuit included in the second DC / AC converter 6 includes:
To convert DC to AC, power MOSFETs and I
It is assumed that a half-bridge circuit or a full-bridge circuit is configured by the GBT. The first DC / AC converter 4 is subjected to an AC conversion by a current control system, and the second DC / AC converter 6 is subjected to an AC conversion by a voltage control system. I have.

With this configuration, the second DC / AC converter 6 outputs a stable AC at a set constant voltage and a constant frequency, regardless of the state of the system on the commercial power supply 7 side, and outputs the result to a personal computer or a measurement system. It can be supplied to the dedicated load 8 which is an information processing device such as a container.

Since the power from the DC power supply 2 other than that required to supply the power to the dedicated load 8 is surplus power,
By making the power flow reverse to the commercial power source 7 and selling the power to the power company, the energy can be more effectively utilized.

On the other hand, if the dedicated load 8 is a variable load such as a monitor having a power saving function and the power consumption increases and decreases during use and standby, the first DC / AC converter 4 and the second DC / AC converter 4 Competition for the power supplied from the DC power supply 2 occurs between the DC power supply unit 6 and the DC / AC conversion unit 6, and as a result, the load voltage decreases or fluctuates.

Therefore, the second DC / AC converter 6 included in the power converter D2 has an output detecting means 10 at the output unit, and detects a current, a voltage value, and the like output to the dedicated load 8, and detects the detected value. The output value of the second DC / AC converter 6 is fed back to the first DC / AC converter 4 and input detection for detecting the input state from the output detection means 9 and the DC power supply 2 of the first DC / AC converter 4. The information from the means 11 is added, and the connection operation control with the system on the commercial power supply 7 side is performed.

As described above, in the power supply system S2, by performing the control for giving priority to the output control for the dedicated load 8, more stable power supply is performed even if the load capacity of the dedicated load 8 fluctuates. It becomes possible.

Next, another embodiment, a power supply system S3 provided with a power converter D3 shown in FIG. 3 will be described.

Here, the power conversion device D3 eliminates the need for the input detection means 11 in the power conversion device D2 shown in FIG. 2, and further includes a power storage means 13 between the first DC / AC converter 4 and the DC power supply 2. Connected to the storage means 13
The second DC / AC converter 6 is connected to the connection line between the first DC / AC converter 4 and the rectifier 12 between the first DC / AC converter 4 and the second DC / AC converter 6 It is. In addition, the DC power supply 2 is a power generation means such as a solar cell or a wind power generation means, which cannot always secure a constant power generation amount.

The DC power obtained by the DC power supply 2 which is a solar cell is connected to and supplied to the first DC / AC converter 4 of the power converter 1 and connected via the rectifier 12, for example, the secondary power. Power storage means 13 such as a battery or a capacitor
Is charged. The power storage unit 13 is connected to the second DC / AC converter 6, and the second DC / AC converter 6 is supplied with DC power from either or both of the DC power supply 2, which is a solar cell, and the power storage unit 13. Take the configuration.

The first DC / AC converter 4 converts the sine wave into a commercial AC waveform, and performs a system interconnection operation with the commercial power system 7. Similarly, in the second DC / AC converter 6, the DC power obtained by the DC power supply 2 and / or the power storage unit 13 is converted into a sine-wave commercial AC waveform by a self-sustaining operation and output to the dedicated load 8.

However, since the DC power supply 2 is a solar cell, the amount of supplied power depends on time and weather due to its characteristics. In addition, since there is no power generation unless there is solar radiation such as at night, power cannot be supplied. Therefore, the above configuration is adopted, and the power is stored in the power storage means 8 so that the power can be supplied during a time when the solar battery cannot generate power. I am trying to. By adopting such a method, stable power supply can be achieved even when the DC power supply 2 uses a power generation unit such as a solar cell or a wind power generation unit that cannot always secure a constant power generation amount.

Further, unlike a solar cell system using a combination of a normal solar cell and a storage battery, when the storage battery is fully charged, the generated power is not wasted and wasted, and the charging of the power storage means 13 is completed. Thereafter, reverse power flows from the first DC / AC converter 4 to the commercial power system 7 to sell the power to the power company, so that the power generation energy can be used effectively.

Further, according to this configuration, even if the dedicated load 8 is a load that temporarily requires a large amount of power at the time of startup, power compensation from the power storage means 13 can be expected, and the power generation capacity of the DC power supply 2 is designed to be large. You don't have to.

Another embodiment will be described. FIG. 4 shows a power supply system S4 including a power conversion device D4. As shown in FIG. 4, the power conversion device D4 includes a rectifier in the power conversion device D3 that connects between the first DC / AC converter 4 and the commercial power supply 7 and between the rectifier 12 and the second DC / AC converter 6. (Or a charger) 14 connected by a connection line L provided in the middle.

As described above, by connecting the power storage means 13 of the power converter 1 to the commercial power supply system 7 via the rectifier (or charger) 14, the rectifier (or The charger 14 is controlled to operate. Therefore, even if the DC power supply 2 stops input due to a failure or the like, or the charging of the power storage unit 13 is insufficient, and the voltage of the power storage unit 13 decreases,
It is possible to provide a highly reliable power converter and a power supply system using the same, in which the power supply to the dedicated load 8 is not interrupted.

If the design is such that charging power is also supplied from the first DC / AC converter 4 so that the power storage means 13 is normally charged, the size of the DC power supply 2 is reduced. You can also Note that this power conversion device D
4 can also be considered to have the same configuration as the power conversion device D2.

In this embodiment, the power converter using a fuel cell, a solar cell, a wind power generation means and the like has been described as an example. However, the present invention is not limited to this. For example, a liquid fuel or a gas fuel is used. The present invention can be applied to a power generation unit, a hydropower unit, and a power generation unit using wave power, and can be applied to any power conversion device that supplies a power generation unit capable of generating DC to two or more AC conversion units. The present invention can be appropriately changed and implemented without departing from the scope.

[0048]

As described above in detail, according to the power converter and the power supply system of the present invention, the first bridge circuit including a plurality of semiconductor switching elements and the first bridge circuit are connected in parallel to the first bridge circuit. A second bridge circuit comprising a plurality of semiconductor switching elements, wherein the AC power converted in the first AC converter having the first bridge circuit is connected to a commercial power supply system, and the second bridge circuit The AC power converted in the second AC converter having the above is output to a dedicated load, and therefore, a stable high power can be applied to a dedicatedly connected load without depending on the state of the commercial power supply system. An excellent power converter and power supply system capable of supplying power of high quality can be provided.

Further, the output of the first AC converter is controlled by the output value detected by the output detecting means provided in the second AC converter, so that the output for the dedicated load is prioritized, and An excellent power conversion device and an excellent power supply system capable of effectively utilizing the energy obtained from a DC power supply by allowing a surplus power to flow backward to a commercial power supply system. it can.

Further, in the power converter, a DC power source such as a fuel cell, a secondary battery, a solar cell, or a wind power generator is used as a power source, and the power converter uses a rectifier to convert the DC power supplied from the DC power source. Power storage means for storing power via the power storage means, the power stored in the power storage means is to be input to the second AC conversion unit, so that when the solar cell as a DC power supply is not generated at night or when the weather Excellent power converter and power supply system that can supply stable power to a dedicated load even when bad enough energy cannot be obtained, when the wind power of the wind power generation means is not enough, or when the commercial power supply system is out of power Can be provided.

In the power converter of the present invention,
Only when the voltage of the power storage means falls below a predetermined value, power is supplied to the power storage means by a rectifier or a charger connected to a commercial power supply system. Even when the voltage of the power storage means is not sufficiently recovered at the time of stoppage, it is possible to provide an excellent power conversion device and an excellent power supply system in which power supply to a dedicated load is not interrupted.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for schematically explaining an embodiment of a power conversion device according to the present invention.

FIG. 2 is a schematic configuration diagram for schematically explaining one embodiment of a power conversion device according to the present invention.

FIG. 3 is a schematic configuration diagram schematically illustrating an embodiment of a power conversion device according to the present invention.

FIG. 4 is a schematic configuration diagram for schematically explaining one embodiment of a power conversion device according to the present invention.

FIG. 5 is a schematic configuration diagram for schematically explaining an example of a conventional grid interconnection system.

FIG. 6 is a schematic configuration diagram for schematically explaining an example of a conventional power converter.

[Explanation of symbols]

 1: power converter 2: DC power supply 3: first bridge circuit 4: first DC / AC converter 5: second bridge circuit 6: second DC / AC converter 7: commercial power supply 8: dedicated load 9: commercial power supply system Output detection means 10: output detection means of the dedicated load output unit 11: input detection means 12: rectifier 13: power storage means 14: rectifier (charger) D1, D2, D3, D4: power converter S1, S2, S3 , S4: Power supply system

Claims (5)

[Claims] 1. A power supply connected between a commercial power supply and a DC power supply,
What is claimed is: 1. A power converter for converting DC of a DC power supply to AC, comprising: a first DC / AC converter having a plurality of semiconductor switching elements and having a first bridge circuit for converting DC to AC; And a second DC / AC converter having a second bridge circuit that is composed of a plurality of semiconductor switching elements and converts DC to AC. The first DC / AC converter is connected to a commercial power supply and a system. A power converter, wherein the second DC / AC converter is connected to a dedicated load. 2. The power converter according to claim 1, wherein an output of said first DC / AC converter is controlled in accordance with an output of said second DC / AC converter. 3. A power supply connected between a commercial power supply and a DC power supply,
A power converter for converting DC of the DC power supply into AC, the power converter supplying DC power from the DC power supply to a power storage unit via a rectifier, and converting the DC power from the power storage unit to the second AC conversion. The power converter according to claim 1, wherein power is supplied to the unit. 4. A rectifier or a charger is connected between the commercial power supply and the first DC / AC converter, and power is supplied from the rectifier or the charger to the second DC / AC converter. The power converter according to claim 3, characterized in that: 5. A power supply system comprising the power converter according to claim 1 connected between a DC power supply and a commercial power supply.