JP2010213479A - Distributed power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe and excellently reliable distributed power supply device which can surely be turned off by preventing damage to a mechanical contact point by an arc current. <P>SOLUTION: The distributed power supply device 102 systematically connected to a commercial power system 101 includes; a power generation device 106, which generates a DC voltage; a first DC-DC converter 107, which converts the DC voltage generated by the power generation device 106 into a different voltage; a DC load 108 connected to the first DC-DC converter 107 via the mechanical contact point 109; and a control means 112, which controls the first DC-DC converter 107. The control means 112 has a structure to change the output voltage of the first DC-DC converter 107 to virtually 0V periodically. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a distributed power supply apparatus that supplies AC power to a home load in linkage with a commercial power system.

  Conventionally, as a distributed power supply device, for example, configurations shown in FIGS. 8 and 9 have been disclosed (see, for example, Patent Document 1).

  The distributed power supply device disclosed in Patent Document 1 will be described below.

  FIG. 8 is a block diagram of a conventional distributed power supply apparatus. As shown in FIG. 8, the distributed power supply device includes a power generator 1 composed of a fuel cell, a first DC / DC converter 2, a second DC / DC converter 3, an inverter 4, an AC load 5, a reverse flow monitoring sensor 6, and power control. It comprises at least a part 7 and a DC load 8 and is connected to the commercial power system 10 via the interconnection part 9.

  Here, the output voltage of the power generator 1 is input to the first DC / DC converter 2, and the input voltage is converted into a DC voltage (for example, DC25V) having a different voltage value and output. The second DC / DC converter 3 receives the output voltage of the power generation device 1, converts the input voltage to a DC voltage (for example, DC 140 V) having a different voltage value, and outputs the converted voltage. The inverter 4 receives the output voltage of the second DC / DC converter 3, converts the input voltage into an AC voltage (for example, AC 100 V), and outputs the AC voltage.

  The AC load 5 is driven using the AC voltage supplied from the inverter 4 as a power supply voltage. The reverse flow monitoring sensor 6 monitors (detects) whether the current of the inverter 4 is not flowing to the commercial power system 10 side, that is, whether the reverse flow is not flowing. The power control unit 7 controls the output power of the power generator 1, the first DC / DC converter 2, and the inverter 4 with reference to the information on the reverse flow from the reverse flow monitoring sensor 6 and the system stop signal from the interconnection unit 9. To do. The DC load 8 is driven by a DC voltage supplied from the first DC / DC converter 2.

  Here, a configuration in which the heater that is the DC load 8 heats water will be described as an example with reference to FIG. FIG. 9 is a configuration diagram illustrating a configuration in which a heater of a conventional distributed power supply apparatus heats water.

  As shown in FIG. 9, a DC load 8 driven by a DC voltage supplied from the first DC / DC converter 2, a heating unit 51 in which water flows at a predetermined flow rate, and a pipe for supplying water to the heating unit 51 52, 53, a hot water storage tank 54, and a temperature sensor 55 for detecting the temperature of the hot water storage tank.

  The distributed power supply configured as described above outputs the output of the inverter 4 when a reverse power flow occurs due to a reduction in power consumption of the AC load 5 or when a system stop signal is received from the interconnection unit 9. Decrease or stop. At the same time, surplus power generated by the power generation device 1 is processed by the DC load 8 by increasing the output of the first DC / DC converter 2.

At this time, the DC load 8 heats the water inside the heating unit 51 according to the amount of power supplied from the first DC / DC converter 2. The heated water is sent to the hot water storage tank 54 through the pipes 52 and 53. Here, the temperature sensor 55 detects the temperature of the water (hot water) in the hot water storage tank 54 and sends the detection result to the power control unit 7. And based on a detection result, the electric power control part 7 changes the flow volume of the water which flows into the inside of the heating part 51, and prevents abnormal heating of the water inside the heating part 51 itself or the heating part 51.
JP 2006-67757 A

  However, in the above-described conventional configuration, when a high voltage is input to the DC load 8 due to a failure of the first DC / DC converter 2 and the output of the DC load 8 is increased, water is blocked due to clogging in the pipes 52 and 53. When it stays, it had the subject that the DC load 8, the heating part 51 itself, and the water in the heating part 51 became abnormally high temperature.

  As a means for solving the above-mentioned problem, when detecting an abnormally high temperature of the DC load 8 or the heating unit 51, the first DC / DC converter 2 that turns off the mechanical contact made of an over-temperature prevention device such as a bimetal thermostat is provided. For example, a configuration in which a DC load 8 such as a heater is connected is conceivable.

  However, when a mechanical contact such as a bimetal thermostat is turned off, an arc current may be generated depending on the magnitude of the voltage input to the DC load 8, that is, the magnitude of the direct current flowing through the bimetal thermostat. Therefore, the mechanical contact is damaged by the arc current and cannot be turned off instantaneously. In the worst case, there is a problem that the DC load 8 always consumes electric power because it cannot be turned off by welding of the mechanical contacts.

  The present invention solves the above-described conventional problems, and provides a safe and reliable distributed power supply device that can prevent damage to mechanical contacts due to arc current and can be reliably turned off. Objective.

  In order to solve the above-described conventional problems, a distributed power supply apparatus according to the present invention includes a power generation apparatus that generates DC voltage power and a DC voltage generated by the power generation apparatus in a distributed power supply system connected to a commercial power system. A first DC / DC converter for converting the voltage into a different voltage, a DC load connected to the first DC / DC converter via a mechanical contact, and a control means for controlling the first DC / DC converter. The output voltage of the 1DC / DC converter is periodically made substantially 0V.

  Thereby, damage to the mechanical contact due to the arc current generated when the mechanical contact connected between the first DC / DC converter and the DC load is turned off can be prevented and turned off reliably.

  According to the present invention, when the mechanical contact connected between the first DC / DC converter and the DC load is turned off, the mechanical contact is prevented from being damaged by the arc current, and is securely turned off by securely turning it off. An apparatus can be realized.

  According to a first aspect of the present invention, there is provided a distributed power supply device interconnected with a commercial power system, a power generation device that generates a DC voltage, a first DC / DC converter that converts a DC voltage generated by the power generation device into a different voltage, and a mechanical type A DC load connected to the first DC / DC converter via the contact and a control means for controlling the first DC / DC converter are provided, and the control means periodically sets the output voltage of the first DC / DC converter to substantially 0V. It has a configuration.

  With this configuration, when the mechanical contact is turned off, it is possible to realize a safe distributed power supply device that prevents the mechanical contact from being damaged by an arc current and securely turns off.

  According to a second invention, in the first invention, the control means controls the output voltage of the first DC / DC converter so as to gently fall and rise. Accordingly, it is possible to prevent an excessive load due to overshoot or undershoot applied to the switching element, the smoothing circuit, the DC load, the wiring, and the like, and to realize a long life of the distributed power supply device.

  According to a third invention, in the first or second invention, the control means periodically selects one of a period in which the output voltage of the first DC / DC converter is periodically substantially 0 V and a time in which the output voltage is substantially 0 V. It changes according to the output voltage of the first DC / DC converter. As a result, a safe distributed power supply apparatus that can efficiently apply a voltage to a DC load and reliably turn off the mechanical contact is realized.

  According to a fourth invention, in any one of the first to third inventions, the first DC / DC converter includes an insulating transformer that performs transformation in a state where the input side and the output side are insulated. As a result, a high frequency (harmonic) generated by the operation of the first DC / DC converter is prevented from becoming a leakage current through a grounded floating capacitance such as a DC load or a housing, and a safe distributed power supply device is realized. it can.

  According to a fifth invention, in any one of the first to fourth inventions, a second DC / DC converter that converts a DC voltage generated by the power generator into a different DC voltage between the power generator and the first DC / DC converter. Is intervening. Thereby, the heat loss of the first DC / DC converter, for example, due to the winding resistance of the transformer, the switching loss of the power device, and the like can be reduced, and a highly efficient distributed power supply device can be realized.

  According to a sixth invention, in any one of the first to fourth inventions, the mechanical contact is an excessive temperature rise prevention device. Thereby, abnormal overheating when water is heated with a DC load such as a heater to consume surplus power can be prevented.

  In a seventh aspect based on the sixth aspect, the overheat prevention device is a bimetal thermostat. Thereby, the bimetal thermostat which a contact tends to weld can be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, the distributed power supply apparatus according to Embodiment 1 of the present invention will be described in detail.

  FIG. 1 is a block diagram showing a distributed power supply apparatus according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram showing a configuration in which a heater used in the distributed power supply apparatus according to Embodiment 1 of the present invention heats water. FIG. 3 is a characteristic diagram showing the relationship between the applied voltage and time of the heater used in the distributed power supply apparatus according to Embodiment 1 of the present invention.

  In addition to the distributed power supply apparatus 102, the commercial power system 101, the interconnection unit 103, the home load 104, and the received power measuring unit 105 are illustrated in FIG. 1. Here, the commercial power system 101 is a single-phase three-wire AC power source composed of a U phase, an O phase, and a W phase, and the interconnection unit 103 interconnects the commercial power system 101 and the distributed power supply device 102. The household load 104 is a device that consumes AC power supplied from the commercial power system 101 or the distributed power supply device 102. The received power measuring means 105 measures the power received from the commercial power system 101 based on the magnitude, direction and voltage of the current flowing on the line connecting the commercial power system 101 and the distributed power supply device 102. It is a power measuring device.

  As shown in FIG. 1, the distributed power supply apparatus 102 includes a power generation apparatus 106 including a fuel cell that generates direct current, a first DC / DC converter 107, a direct current load 108 such as a heater, and a bimetal thermostat, for example. The mechanical contact 109, the second DC / DC converter 110, the inverter 111, and the control means 112 that constitute the overheat prevention device are configured at least. In the following description, the power generation device 106 is referred to as a fuel cell, the mechanical contact 109 constituting the overheat prevention device is referred to as a bimetal thermostat, and the DC load 108 is referred to as a heater.

  Here, the first DC / DC converter 107 has a configuration including an insulating transformer, and boosts the DC voltage generated by the fuel cell 106. The heater 108 is driven by a DC voltage generated by the first DC / DC converter 107. The bimetallic thermostat 109 is installed between the first DC / DC converter 107 and the heater 108, and has a contact that turns off when the surface temperature of the installed location is equal to or higher than a predetermined value (for example, 90 ° C.).

  The second DC / DC converter 110 boosts the DC voltage generated by the fuel cell 106 to a DC voltage different from that of the first DC / DC converter 107. Further, the inverter 111 converts the direct current output from the second DC / DC converter 110 into an alternating current that can be consumed by the household load 104. Then, the control means 112 controls the output of the first DC / DC converter 107, the second DC / DC converter 110, and the inverter 111.

  At this time, as shown in FIG. 2, the heater 120 and the bimetal thermostat 109 are installed on the surface of the pipe 120, and the water flowing at a predetermined flow rate inside the first DC / DC is turned on when the bimetal thermostat 109 is turned on. Heated by the heater 108 by the DC voltage supplied from the converter 107.

  The operation and action of the distributed power supply device configured as described above will be described with reference to FIGS.

  First, the distributed power supply apparatus 102 boosts the power generated by the fuel cell 106 to a voltage that can be output by the inverter 111 by the second DC / DC converter 110. In the present embodiment, the voltage is boosted to, for example, DC 400V. Inverter 111 converts the boosted voltage from direct current to alternating current (in this embodiment, for example, AC 200 V) and supplies the converted voltage to household load 104.

  At this time, if the power consumption of the household load 104 is larger than the power generated by the fuel cell 106, all the power generated by the fuel cell 106 is consumed by the household load 104.

  Conversely, when the power consumption of the household load 104 is smaller than the power generated by the fuel cell 106, surplus power that is the difference is generated and the power tends to flow into the commercial power system 101 (hereinafter referred to as the commercial power system). The flow into 101 is called “reverse flow”.

  In general, a power generation device such as a fuel cell needs to prevent reverse power flow from the viewpoint of power cost and safety of the commercial power system 101 (for example, increase in AC voltage due to reverse power flow).

  Therefore, the power flowing backward is always measured by the received power measuring device that is the received power measuring means 105, and when the reverse power flow occurs, the output of the inverter 111 is output by the control unit that is the control means 112 based on the measured power. To prevent reverse power flow. Furthermore, when the commercial power system 101 stops, the stop of the commercial power system 101 is detected and the output of the inverter 111 is stopped to prevent reverse power reception of the commercial power system 101. In the present embodiment, the description of the power failure detection method is omitted.

  However, since it is difficult to rapidly reduce the generated power of the fuel cell 106, when the output of the inverter 111 is rapidly reduced or stopped, surplus power is generated inside the distributed power supply device 102. Therefore, it is necessary to consume surplus power.

  Therefore, when the output of the inverter 111 is decreased or stopped, the control unit 112 increases the output of the first DC / DC converter 107 shown in FIG. 2 and heats the water flowing through the pipe 120 with the heater 108, thereby surplus. Control to consume power.

  However, as described above, the water in the pipe 120 or the pipe 120 may become abnormally high due to the failure of the first DC / DC converter 107 or the heater 108 or the retention of water due to clogging in the pipe 120. .

  In order to avoid this, generally, when a bimetal thermostat 109 is arranged between the first DC / DC converter 107 and the heater 108 and the surface temperature of the pipe 120 becomes high, the contact of the bimetal thermostat 109 is turned off. ing. Thereby, the output of the first DC / DC converter is cut off, and the water in the pipe 120 and the pipe 120 is prevented from becoming an abnormally high temperature.

  However, since the bimetal thermostat 109 always has direct current flowing while surplus power is consumed, the bimetal thermostat 109 tries to maintain the connection via the arc current when the contact is turned off. At this time, when the contact is damaged due to the arc current, for example, when it is welded, it may not be normally turned off.

  Therefore, in the present embodiment, as shown in FIG. 3, the control unit 112 controls the output of the first DC / DC converter 107 so that the applied voltage of the heater 108 is periodically substantially 0V. For example, for a period of T1 (for example, 50 ms), a time of T2 (for example, 1 ms) is set to 0V.

  As a result, when the contact point of the bimetal thermostat 109 is turned OFF, the voltage applied to the heater 108 becomes 0V, and the flowing current also becomes 0. As a result, there is no arc current, and the contact can be reliably turned off.

  In the present embodiment, since the voltage generated by the fuel cell 106 is low, the first DC / DC converter 107 and the second DC / DC converter 110 boost the voltage. However, the present invention is not limited to this. For example, when a power generation device that generates a high voltage, such as a solar battery or wind power generation, is used, the voltage may be reduced.

  In the present embodiment, the example in which the bimetal thermostat 109 is used as the mechanical contact in order to turn off the contact between the first DC / DC converter and the heater according to the temperature of the pipe 120 has been described. Absent. For example, a temperature sensor such as a thermistor may be used to measure the temperature of the pipe, and the overheat prevention device may be configured by a separate means such as a mechanical contact configured by a switch such as a relay having a contact. Effects and operations can be realized.

  As described above, according to the present embodiment, by periodically setting the output voltage of the first DC / DC converter 107 to substantially 0 V, the bimetal thermostat by the arc current when the bimetal thermostat 109 is turned OFF. Damage to 109 contacts can be prevented. As a result, it is possible to realize a distributed power supply device that is safe and has long-term reliability.

(Embodiment 2)
Hereinafter, a distributed power supply apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings.

  FIG. 4 is a characteristic diagram showing the relationship between the applied voltage of the heater and time in Embodiment 2 of the present invention.

  That is, as shown in FIG. 4, the distributed power supply apparatus according to the present embodiment is different in the heater control method from the method described with reference to FIG. 3 in the first embodiment. Note that the configuration and operation of the distributed power supply are the same as those in the first embodiment, and a description thereof will be omitted.

  Hereinafter, control of the heater of the distributed power supply apparatus according to the present embodiment will be described with reference to FIG.

  Basically, similarly to the first embodiment, when the output of the inverter 111 is decreased or stopped, the control unit 112 increases the output of the first DC / DC converter 107 shown in FIG. Excess power is consumed by heating the water flowing inside.

  That is, in the present embodiment, as shown in FIG. 4, the control unit 112 controls the output of the first DC / DC converter 107 so that the applied voltage of the heater 108 is periodically substantially 0V. For example, the time of T4 (for example, 1 ms) is set to 0 V with respect to the period of T3 (for example, 50 ms).

  At this time, as shown in FIG. 4, when the output voltage of the first DC / DC converter 107 is set to 0V, the output voltage is generally gradually lowered or gradually lowered to 0V, which is generally called soft stop. Thereafter, the voltage is maintained at 0 V for the time T4, and then the output voltage is gradually or gradually increased, which is generally called soft start. For example, the output voltage drop rate or rise rate is about 100 V / ms.

  In this embodiment, the output voltage drop rate and the increase rate have been described using the same example. However, the output voltage drop rate and the increase rate are not limited to this example, and are set separately according to the characteristics (voltage, current, surplus power) of the distributed power supply device 102. May be. For example, the output voltage drop rate is such that the input / output voltage of the first DC / DC converter 107 does not become an overvoltage even if the first DC / DC converter 107 suddenly stops. What is necessary is just to set according to the rise or fall degree. Also, the rate of increase of the output voltage is such that the first DC / DC converter 107 is not overloaded by the inrush current of the heater 108 even if the first DC / DC converter 107 suddenly starts operation. It may be set according to

  As described above, according to the present embodiment, the control unit 112 moderates the rate of decrease and the rate of increase of the output voltage of the first DC / DC converter 107, thereby switching elements, smoothing circuits, and DC loads. In addition, it is possible to prevent an excessive load due to overshoot or undershoot applied to the wiring and the like, and to realize a long life of the distributed power supply device.

(Embodiment 3)
Hereinafter, a distributed power supply apparatus according to Embodiment 3 of the present invention will be described with reference to the drawings.

  FIG. 5 is a characteristic diagram showing the relationship between the applied voltage and time of the heater used in the distributed power supply device according to Embodiment 3 of the present invention. FIG. 6 is a characteristic diagram showing the relationship between the applied voltage of the heater used in the distributed power supply apparatus according to Embodiment 3 of the present invention, the period of 0V, and the time of 0V.

  That is, as shown in FIGS. 5 and 6, the distributed power supply apparatus according to the present embodiment is different in the heater control method from the method described with reference to FIG. 3 in the first embodiment. Note that the configuration and operation of the distributed power supply are the same as those in the first embodiment, and a description thereof will be omitted.

  Hereinafter, control of the heater of the distributed power supply apparatus according to the present embodiment will be described with reference to FIGS. 5 and 6.

  Basically, similarly to the first embodiment, when the output of the inverter 111 is decreased or stopped, the control unit 112 increases the output of the first DC / DC converter 107 shown in FIG. Excess power is consumed by heating the water flowing inside.

  That is, in the present embodiment, as shown in FIG. 5, the control unit 112 controls the output of the first DC / DC converter 107 so that the applied voltage of the heater 108 is periodically substantially 0V. For example, the time of T6 is set to 0V with respect to the period of T5.

  At this time, according to the applied voltage of the heater 108, that is, the output voltage of the first DC / DC converter 107, the period of 0 V (T 5 in FIG. 5) and the time of 0 V (T 6 in FIG. 5) are changed.

  In general, the smaller the voltage applied to the heater 108, that is, the voltage applied to the bimetal thermostat 109, the smaller the arc current, the less the contact damage.

  Therefore, as shown in FIG. 6, the period of T5 and the time of T6 to be 0V are variably controlled according to the magnitude of the output voltage of the first DC / DC converter 107. Specifically, when the output voltage of the first DC / DC converter 107 is large, the period of T5 is shortened and the time of T6 for setting to 0 V is lengthened. On the contrary, when the output voltage of the first DC / DC converter 107 is small, the period of T5 is lengthened and the time of T6 to be 0V is shortened.

  As described above, according to the present embodiment, it is possible to realize a safe distributed power supply apparatus that can efficiently apply a voltage to the heater 108 and can reliably turn off the contact of the bimetal thermostat 109.

(Embodiment 4)
The distributed power supply apparatus according to Embodiment 4 of the present invention will be described in detail below.

  FIG. 7 is a block diagram showing a distributed power supply apparatus according to Embodiment 4 of the present invention. 7, as in the first embodiment described with reference to FIG. 1, in addition to the distributed power supply device 102, the commercial power system 101, the interconnection unit 103, the home load 104, and the received power measurement The means 105 is also illustrated. In FIG. 7, the same components as those in FIG.

  That is, as shown in FIG. 7, the first DC / DC converter 107 connected to the heater 108 that is a DC load is connected between the second DC / DC converter 110 and the inverter 111 via a bimetal thermostat 109 having a contact. This is different from the first embodiment.

  At this time, the first DC / DC converter 107 is configured to convert the voltage output from the second DC / DC converter 110 into a different voltage and output the converted voltage to the heater 108 via the bimetal thermostat 109.

  The operation and action of the distributed power supply device configured as described above will be described with reference to FIGS. 2, 3, and 7.

  As described above, when the output of the inverter 111 is decreased or stopped, the control unit 112 increases the output of the first DC / DC converter 107 shown in FIG. 2 and heats the water flowing through the pipe 120 by the heater 108. Thus, surplus power is consumed.

  Therefore, in the present embodiment, as shown in FIG. 3, the control unit 112 maintains the output of the second DC / DC converter 110 and the first DC so that the applied voltage of the heater 108 becomes substantially 0 V periodically. / Controls the output of the DC converter 107. For example, for a period of T1 (for example, 50 ms), a time of T2 (for example, 1 ms) is set to 0V.

  At this time, in order to prevent a large current from flowing through the heater 108, it is necessary to increase the applied voltage of the heater 108, that is, to increase the output voltage of the first DC / DC converter 107. This is because the heat generation of the heater 108 is determined by the product of voltage and current. In general, the second DC / DC converter 110 generates a high voltage (for example, 400 V) so that the inverter 111 can output an AC voltage of 200 V.

  That is, by interposing the second DC / DC converter 110 between the fuel cell 106 and the first DC / DC converter 107, it is not necessary to boost the voltage applied to the heater 108 to a high voltage by the first DC / DC converter 107. . As a result, a decrease in conversion efficiency of the first DC / DC converter 107 can be prevented.

  In the present embodiment, the first DC / DC converter 107 transforms the high voltage output from the second DC / DC converter 110 by switching at a high frequency in order to reduce the circuit configuration, particularly the shape of the insulating transformer. It is preferable. Furthermore, it is preferable that the insulating transformer performs the transformation in a state where the input side and the output side are insulated.

  Thereby, it is possible to prevent the occurrence of a large leakage current that flows in the case of non-insulation and flows through the stray capacitance existing between the heater 108 and the ground.

  As described above, according to the present embodiment, it is possible to prevent the high frequency generated by the operation of the first DC / DC converter 107 from becoming a leakage current via the ground floating capacitance such as the heater 108 or the housing. . As a result, a safe and reliable distributed power supply device can be realized.

  Further, according to the present embodiment, the second DC / DC converter 110 that converts the DC voltage generated by the fuel cell 106 into a different DC voltage is interposed between the heater 108 and the first DC / DC converter 107. Therefore, it is possible to suppress a decrease in the conversion efficiency of the first DC / DC converter 107 and realize a highly efficient distributed power supply apparatus.

  Further, according to the present embodiment, since the first DC / DC converter can be transformed by switching at high frequency, the circuit configuration can be reduced by downsizing the first DC / DC converter, and a small distributed power supply device can be realized. .

  In each embodiment, a fuel cell has been described as an example of a power generation device, but is not limited thereto. For example, a solar power generation device, a wind power generation device, a solar thermal power generation device, or the like may be used, and similar effects and operations can be obtained.

  According to the present invention, the mechanical contact constituting the overheat prevention device can be prevented from being damaged by the arc current and reliably turned off. Therefore, the fuel cell device, the solar power generation device, the wind power generation device, and the solar thermal power generation This is useful in the technical field of distributed power supply devices such as devices.

1 is a block diagram showing a distributed power supply device according to a first embodiment of the present invention. The block diagram which shows the structure which the heater used for the distributed power supply device in the embodiment heats water The characteristic figure which shows the relationship between the applied voltage and time of the heater used for the distributed power supply device in the same embodiment The characteristic view which shows the relationship between the applied voltage of a heater used for the distributed power supply device in Embodiment 2 of this invention, and time The characteristic view which shows the relationship between the applied voltage of a heater used for the distributed power supply device in Embodiment 3 of this invention, and time The characteristic view which shows the relationship between the applied voltage of the heater used for the distributed power supply device in the same embodiment, the cycle of 0V, and the time of 0V The block diagram which shows the distributed power supply device in Embodiment 4 of this invention Block diagram of a conventional distributed power supply The block diagram explaining the structure which the heater of the conventional distributed power supply device heats water

DESCRIPTION OF SYMBOLS 101 Commercial power system 102 Distributed power supply device 103 Interconnection part 104 Domestic load 105 Received power measuring means 106 Power generation device (fuel cell)
107 1st DC / DC converter 108 DC load (heater)
109 Mechanical contact (bimetal thermostat)
110 Second DC / DC converter 111 Inverter 112 Control means

Claims (7)

A distributed power supply device that is connected to a commercial power system, a power generation device that generates DC voltage power, a first DC / DC converter that converts a DC voltage generated by the power generation device into a different voltage, and a mechanical contact And a control means for controlling the first DC / DC converter, wherein the control means periodically substantially outputs the output voltage of the first DC / DC converter. A distributed power supply unit with 0V. 2. The distributed power supply apparatus according to claim 1, wherein the control unit controls the output voltage of the first DC / DC converter so as to gently drop and increase. The control means determines either one of a period when the output voltage of the first DC / DC converter is periodically substantially 0V and a time when the output voltage is substantially 0V according to the output voltage of the first DC / DC converter. The distributed power supply device according to claim 1 or 2, wherein the distributed power supply device is changed. 4. The distributed power supply device according to claim 1, wherein the first DC / DC converter includes an insulating transformer that performs transformation in a state where an input side and an output side are insulated. 5. 5. The first DC / DC converter according to claim 1, wherein a second DC / DC converter that converts a direct current voltage generated by the power generation device into a different direct current voltage is interposed between the power generation device and the first DC / DC converter. Distributed power supply. The distributed power supply device according to any one of claims 1 to 5, wherein the mechanical contact is an overheat prevention device. The distributed power supply device according to claim 6, wherein the overheat prevention device is a bimetal thermostat.

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