JP6993159B2 - Power conversion device and power conversion method - Google Patents

Description

The present invention relates to a power conversion device and a power conversion method.

Patent Document 1 discloses a power conversion device that supplies power to a load by connecting the DC power generated by the solar cell module to a commercial power system. This power conversion device includes an inverter circuit having a switching element that converts the DC voltage of the DC power generated by the solar cell module into an AC voltage, an inverter control circuit that controls the inverter circuit, and the presence of people around the power conversion device. It is equipped with a means of detecting a person who senses it. When the human sensing means detects the presence of a person, the inverter control circuit controls to raise the switching frequency, and the inverter circuit switches the switching element on and off based on this switching frequency to convert the DC voltage into an AC voltage. .. On the contrary, when the human sensing means does not detect the presence of a human, the inverter control circuit controls to lower the switching frequency.
As described above, in the power conversion device of Patent Document 1, when the presence of a human is detected, the power conversion efficiency is lowered, but the switching frequency is increased to satisfy the noise performance, and when the presence of a human is not detected, the switching frequency is satisfied. Can be lowered to improve the power conversion efficiency.

Japanese Unexamined Patent Publication No. 2005-210853

When another electronic device is connected to a power generation device such as a solar cell module, there is a problem that the other electronic device generates an abnormal noise due to the influence of the AC voltage of the power generation device. In the power generation device of Patent Document 1, the noise is controlled only by the presence or absence of a person, and when another electronic device is connected to the power generation device, the influence of noise and flicker of lighting occurs. Does not pay attention at all and does not provide any technique for reducing the influence of such noise and lighting flicker.

Therefore, an object of the present invention is to provide a power conversion device and a power conversion method capable of suppressing an influence on other electronic devices in a power generation device to which another electronic device is connected.

The characteristic configuration of the power conversion device according to the present invention is
An inverter circuit that has a switching element that converts the DC voltage of the DC power generated by the power generation device into an AC voltage and forms a closed circuit.
A harmonic component determination unit that determines whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the harmonic component determination unit determines that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains the harmonic component, the switching frequency of the switching element is set to a predetermined value. Equipped with a frequency control unit to raise
The case where it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component is the case where another electronic device is connected to the power conversion device. The point is that the other electronic device is affected by the harmonic component and generates an abnormal sound having a frequency in the audible range, or causes light flicker .

The inverter circuit of the power conversion device is a device that converts the DC voltage generated by the power generation device into an AC voltage, but the power waveform of the converted AC voltage includes the generated waveform that the power conversion device is about to generate. , Harmonic components affected by the switching frequency of the inverter circuit are included. Then, when an electronic device other than the power generation device is connected to the power conversion device, if the AC voltage from the power generation device flows into the other electronic device while containing the harmonic component, the other electronic device becomes a harmonic. Abnormal noise may be generated due to the influence of the components, and the lighting may flicker.

According to the characteristic configuration of the present invention, when it is determined that the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the switching frequency of the inverter circuit is controlled to be increased. Since the harmonic component is generated in synchronization with the switching frequency of the inverter circuit, increasing the switching frequency also increases the frequency of the harmonic component. As a result, the frequency of the abnormal sound generated from other electronic devices due to the influence of the harmonic component approaches the outside of the audible range or the outside of the audible range. Therefore, the abnormal noise becomes hard to hear, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.

In addition, the power conversion device controls the switching frequency to suppress noise generation and lighting flicker due to abnormal noise of other electronic devices connected to the power conversion device. Therefore, it is not necessary for other electronic devices to be equipped with a device for suppressing noise generation due to abnormal noise and flicker of lighting, and further, it is necessary for other electronic devices to control for noise suppression and flicker suppression. There is no. Therefore, even when a device for suppressing noise and flicker and another new electronic device having no control are connected to the power conversion device, the power conversion device causes noise caused by abnormal noise caused by the new electronic device. It is possible to suppress the occurrence and flickering of lighting. As a result, the degree of freedom in connecting a new electronic device to the power conversion device can be improved.

Moreover,
When the harmonic component determination unit determines that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains the harmonic component, the frequency control unit determines the switching frequency. The following effects can be obtained by increasing the value by a predetermined value.

The harmonic component determination unit can automatically determine whether or not the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component.

Further characteristic configurations of the power conversion device according to the present invention are
The frequency control unit is at a point where the switching frequency is increased when the frequency of the harmonic component determined to be included in the AC voltage output to the outside from the closed circuit of the inverter circuit is equal to or lower than the threshold value.

When the frequency of the harmonic component that goes out from the closed circuit of the inverter circuit is as low as below the threshold value, when another electronic device is connected to the power converter, the other electronic device is affected by the low frequency harmonic component and is different. It produces sound and causes noise problems. In addition, the problem of lighting flicker may occur due to the influence of low-frequency harmonic components.

According to the characteristic configuration of the present invention, when the frequency of the harmonic component is as low as the threshold value or less, the switching frequency of the inverter circuit is increased to increase the frequency of the harmonic component. This suppresses noise caused by abnormal noise generated from other electronic devices due to the influence of harmonic components, flicker of lighting, and the like.

Further characteristic configurations of the power conversion device according to the present invention are
The frequency control unit is at a point of raising the switching frequency to a frequency outside the audible range.

When the AC voltage going out from the closed circuit of the inverter circuit contains a harmonic component, other electronic devices connected to the power converter may be affected by the harmonic component to generate an abnormal noise. Therefore, by raising the switching frequency to a frequency outside the audible range, it is possible to suppress abnormal noise generated from other electronic devices due to the influence of harmonic components, which makes it difficult to hear and becomes noise.

Further characteristic configurations of the power conversion device according to the present invention are
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit no longer contains the harmonic component after the switching frequency is increased, the frequency control unit may perform the frequency control unit. The point is to lower the switching frequency by a predetermined value.

The frequency control unit controls to raise the switching frequency when it is determined that the power waveform of the AC voltage contains a harmonic component, and then lowers the switching frequency when the harmonic component is no longer included. Since the harmonic component is no longer included in the power waveform of the AC voltage, the influence of the harmonic component on other electronic devices connected to the power converter is eliminated, and noise due to abnormal noise and flickering of lighting occur. Hateful. In this case, the power conversion efficiency of the power conversion device can be improved by lowering the switching frequency.

Further characteristic configurations of the power conversion device according to the present invention are
When it is determined that the power waveform of the AC voltage contains a harmonic component, a notification unit that notifies the switching frequency to be increased by a predetermined value and a notification unit.
After the notification by the notification unit, the setting reception unit that accepts the setting of the setting frequency that can raise the switching frequency by a predetermined value, and the setting reception unit.
Further prepare
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the frequency control unit receives the switching frequency at the setting reception unit. The point is to raise the frequency to the set frequency.

When an electronic device other than a power generator is connected to a power converter and the AC voltage from the power generator flows into another electronic device while containing the harmonic component, the other electronic device is affected by the harmonic component. In response to this, abnormal noise may occur, and lighting may flicker.

According to the above-mentioned feature configuration, when the AC voltage including the harmonic component is output to the outside from the closed circuit of the inverter circuit, it is notified and the set frequency which can raise the switching frequency by a predetermined value is accepted. .. By setting the switching frequency of the switching element to this set frequency, the frequency of the harmonic component also rises. As a result, the frequency of the abnormal sound generated from other electronic devices due to the influence of the harmonic component approaches the outside of the audible range or the outside of the audible range. As a result, abnormal noise becomes hard to hear, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.

Further characteristic configurations of the power conversion device according to the present invention are
The setting receiving unit is configured to be able to receive the setting of the set frequency step by step.

By being able to adjust the set frequency step by step, the switching frequency is controlled so that it does not become excessively high, and while suppressing noise and lighting flicker due to the influence of harmonic components, the power conversion efficiency of the power converter is reduced. Can be suppressed.

Further characteristic configurations of the power conversion device according to the present invention are
After the switching frequency is increased, when the harmonic component determination unit determines that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit no longer contains the harmonic component, the notification unit Notifies the switching frequency to be lowered by a predetermined value,
The setting receiving unit receives a setting of a setting frequency capable of lowering the switching frequency by a predetermined value, and receives the setting.
The frequency control unit is at a point of lowering the switching frequency to the set frequency received by the setting reception unit.

If the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit does not contain harmonic components, other electronic devices are affected by the harmonic components, causing noise due to abnormal noise and flickering of lighting. Etc. are less likely to occur. In this case, the power conversion efficiency of the power conversion device can be improved by lowering the switching frequency.

Further characteristic configurations of the power conversion device according to the present invention are
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the setting frequency is set so that the switching frequency can be increased by a predetermined value. Setting reception unit that accepts
The frequency control unit raises the switching frequency to a set frequency received by the setting reception unit.

When an electronic device other than the power generator is connected to the power converter and the AC voltage from the power generator flows into the other electronic device while containing the harmonic component, the other electronic device becomes the harmonic component. It may generate abnormal noise due to the influence, and may cause flickering of lighting. According to this feature configuration, when the user inputs a set frequency capable of raising the switching frequency by a predetermined value to the setting reception unit based on the generation of abnormal noise, flickering of lighting, etc., the frequency control unit performs the switching frequency. To the set frequency. As a result, the frequency of abnormal sound generated from other electronic devices due to the influence of the harmonic component can be brought closer to the outside of the audible range or the outside of the audible range, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.

Further characteristic configurations of the power conversion device according to the present invention are
The setting receiving unit is configured to be able to receive the setting of the set frequency step by step.

By adjusting the set frequency step by step, the switching frequency is controlled so that it does not become excessively high, and the power conversion efficiency of the power converter can be improved while suppressing problems such as noise and lighting flicker due to the influence of harmonic components. It can be suppressed from decreasing.

The characteristic configuration of the power conversion method according to the present invention is
A power conversion method in a power conversion device having a switching element and an inverter circuit forming a closed circuit.
A step of converting the DC voltage of the DC power generated by the power generation device into an AC voltage by switching the switching element.
A step of determining whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, a step of increasing the switching frequency of the switching element by a predetermined value is provided . ,
The case where it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component is the case where another electronic device is connected to the power conversion device. It is at least one of the cases where other electronic devices are affected by the harmonic component to generate an abnormal sound having a frequency in the audible range and generate light flicker .

Similar to the above, problems such as noise due to abnormal noise and flickering of lighting can be suppressed, and the degree of freedom in connecting a new electronic device to the power conversion device can be improved.

Further characteristic configurations of the power conversion method according to the present invention are
When it is determined that the power waveform of the AC voltage contains a harmonic component, a step of notifying the switching frequency to be increased by a predetermined value and a step of notifying the user to increase the switching frequency by a predetermined value.
After the notification, the step of accepting the setting of the set frequency that can raise the switching frequency by a predetermined value, and
Further prepare
The step of raising the switching frequency of the switching element by a predetermined value is to raise the switching frequency to the set frequency.

Similar to the above, problems such as noise due to abnormal noise and flickering of lighting can be suppressed, and the degree of freedom in connecting a new electronic device to the power conversion device can be improved.

Further characteristic configurations of the power conversion method according to the present invention are
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the setting frequency is set so that the switching frequency can be increased by a predetermined value. With more steps to accept
The step of raising the switching frequency of the switching element by a predetermined value is to raise the switching frequency to the set frequency.

Similar to the above, problems such as noise due to abnormal noise and flickering of lighting can be suppressed, and the degree of freedom in connecting a new electronic device to the power conversion device can be improved.
The characteristic configuration of the power conversion device according to the present invention is
An inverter circuit that has a switching element that converts the DC voltage of the DC power generated by the power generation device into an AC voltage and forms a closed circuit.
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, a frequency control unit that raises the switching frequency of the switching element by a predetermined value is provided.
A harmonic component determination unit that determines whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the power waveform of the AC voltage contains a harmonic component, a notification unit that notifies the switching frequency to be raised by a predetermined value and a notification unit.
After the notification by the notification unit, the setting reception unit that accepts the setting of the set frequency that can raise the switching frequency by a predetermined value, and the setting reception unit.
Further prepare
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the frequency control unit raises the switching frequency to the set frequency received by the setting reception unit. At the point.
The inverter circuit of the power conversion device is a device that converts the DC voltage generated by the power generation device into an AC voltage, but the power waveform of the converted AC voltage includes the generated waveform that the power conversion device is about to generate. , Harmonic components affected by the switching frequency of the inverter circuit are included. Then, when an electronic device other than the power generation device is connected to the power conversion device, if the AC voltage from the power generation device flows into the other electronic device while containing the harmonic component, the other electronic device becomes a harmonic. Abnormal noise may be generated due to the influence of the components, and the lighting may flicker.
According to the characteristic configuration of the present invention, when the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the switching frequency of the inverter circuit is controlled to be increased. Since the harmonic component is generated in synchronization with the switching frequency of the inverter circuit, increasing the switching frequency also increases the frequency of the harmonic component. As a result, the frequency of the abnormal sound generated from other electronic devices due to the influence of the harmonic component approaches the outside of the audible range or the outside of the audible range. Therefore, the abnormal noise becomes hard to hear, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.
In addition, the power conversion device controls the switching frequency to suppress noise generation and lighting flicker due to abnormal noise of other electronic devices connected to the power conversion device. Therefore, it is not necessary for other electronic devices to be equipped with a device for suppressing noise generation due to abnormal noise and flicker of lighting, and further, it is necessary for other electronic devices to control for noise suppression and flicker suppression. There is no. Therefore, even when a device for suppressing noise and flicker and another new electronic device having no control are connected to the power conversion device, the power conversion device causes noise caused by abnormal noise caused by the new electronic device. It is possible to suppress the occurrence and flickering of lighting. As a result, the degree of freedom in connecting a new electronic device to the power conversion device can be improved.
When an electronic device other than a power generator is connected to a power converter and the AC voltage from the power generator flows into another electronic device while containing the harmonic component, the other electronic device is affected by the harmonic component. In response to this, abnormal noise may occur, and lighting may flicker.
According to the above-mentioned feature configuration, when the AC voltage including the harmonic component is output to the outside from the closed circuit of the inverter circuit, it is notified and the set frequency which can raise the switching frequency by a predetermined value is accepted. .. By setting the switching frequency of the switching element to this set frequency, the frequency of the harmonic component also rises. As a result, the frequency of the abnormal sound generated from other electronic devices due to the influence of the harmonic component approaches the outside of the audible range or the outside of the audible range. As a result, abnormal noise becomes hard to hear, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.
The characteristic configuration of the power conversion method according to the present invention is
A power conversion method in a power conversion device having a switching element and an inverter circuit forming a closed circuit.
A step of converting the DC voltage of the DC power generated by the power generation device into an AC voltage by switching the switching element.
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the step of increasing the switching frequency of the switching element by a predetermined value and
Equipped with
A step of determining whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the power waveform of the AC voltage contains a harmonic component, a step of notifying the switching frequency to be increased by a predetermined value and a step of notifying the user to increase the switching frequency by a predetermined value.
After the notification, the step of accepting the setting of the set frequency that can raise the switching frequency by a predetermined value, and
Further prepare
The step of raising the switching frequency of the switching element by a predetermined value is to raise the switching frequency to the set frequency.
Similar to the above, problems such as noise due to abnormal noise and flickering of lighting can be suppressed, and the degree of freedom in connecting a new electronic device to the power conversion device can be improved.

It is a block diagram when the fuel cell system is arranged in each home as a distributed power source. It is a block diagram of a fuel cell system. It is an electric circuit diagram in which only a power conversion device is connected between a fuel cell and a commercial power system. It is an electric circuit diagram in which a photovoltaic power generation device is connected as another electronic device to a power conversion device connected between a fuel cell and a commercial power system. It is an electric circuit diagram of the power conversion apparatus which concerns on embodiment. It is an example of the flowchart which shows the frequency control flow in the power conversion apparatus which concerns on embodiment. It is an electric circuit diagram of the power conversion apparatus which can accept a switching frequency from a user. It is a schematic diagram of the power conversion apparatus provided with the knob adjustment member.

[Embodiment]
A fuel cell system having a power conversion device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram when a fuel cell system is arranged in each home as a distributed power source.

(1) Configuration of a household equipped with a fuel cell system In each household 10, a fuel cell system 20 including a power generation unit 20a including a fuel cell 1 (power generation device) for generating electric power and a hot water storage tank 20b is installed. .. As equipment used in each home 10, as shown in FIG. 1, for example, hot water supply equipment such as a water heater 10a and a bath 10b, and home appliances such as an air conditioner 10c, lighting 10d, a television 10e, and a refrigerator 10f. Equipment and the like. The hot water supply equipment such as the water heater 10a and the bath 10b is connected to the hot water storage tank 20b of the fuel cell system 20 and receives hot water from the hot water storage tank 20b.

Further, each household 10 is not only supplied with the generated electric power generated by the fuel cell system 20, but also connected to the commercial electric power system 30 to be supplied with the commercial electric power. Therefore, the household appliances such as the air conditioner 10c, the lighting 10d, the television 10e, and the refrigerator 10f of each household 10 have at least one of the electric power generated from the electric power generation unit 20a of the fuel cell system 20 and the commercial electric power from the commercial electric power system 30. It is driven by receiving power from it.

(2) Fuel cell system The fuel cell system 20 will be described below. FIG. 2 is a block diagram of the fuel cell system.
As described above, the fuel cell system 20 includes a power generation unit 20a and a hot water storage tank 20b. The power generation unit 20a is basically composed of a fuel cell 1 that generates power by reacting fuel gas and oxygen gas, a heat exchanger 2 that recovers heat of exhaust gas discharged from the fuel cell 1, and a heat exchanger 2. A water purifier 4 that recovers and purifies condensed water from exhaust gas after heat recovery, a reformed water tank 5 that recovers condensed water purified by the water purifier 4, and reforming independently of the condensed water. It is provided with a water supply unit 6 capable of supplying water to the water tank 5. The fuel cell system 20 is controlled and operated by an operation control unit (not shown).
Hereinafter, the configuration of each part of the fuel cell system 20 will be described.

The fuel cell 1 is provided via a reformer 12 that steam reforms a raw fuel (for example, city gas 13A) supplied through the raw material / fuel flow path 11 to generate fuel gas, and a fuel gas flow path 13. Intervening between the anode 15 to which the fuel gas generated by the reformer 12 is supplied, the cathode 16 to which air (an example of oxygen gas) is supplied via the air flow path 14, and the anode 15 and the cathode 16. It has an electrolyte 17 to be made to react, and the supplied fuel gas and air are reacted to generate power. The fuel cell 1 includes a combustion unit 18 to which the fuel gas and air discharged after being used for the power generation reaction from the anode 15 and the cathode 16 are supplied, and remains in the fuel gas by the combustion unit 18. The fuel component is burned to generate exhaust gas. As will be described later, water is supplied to the reformer 12 from the reforming water tank 5 via the water supply path 52, and the reformer 12 is supplied from the reforming water tank 5. Steam reforming of raw materials and fuels is performed using water.

The exhaust gas discharged from the fuel cell 1 is supplied to the heat exchanger 2 via the exhaust gas supply path 21, and the exhaust gas after heat recovery is exhausted through the exhaust gas discharge path 22. The heat exchanger 2 is supplied with hot water from the hot water storage tank 20b via a circulation path 23 for circulating hot water between the hot water storage tank 20b for storing hot water and the heat exchanger 2. The heat exchanger 2 is adapted to exchange heat between the exhaust gas discharged from the fuel cell 1 and the hot water. The circulation path 23 is provided with a pump 24, a radiator 25 including a heat dissipation fan 25a, a temperature sensor (not shown), and the like. Further, the hot water storage tank 20b is provided with a hot water outlet 31 for discharging the hot water in the hot water storage tank 20b and a water supply channel 32 for supplying water to the hot water storage tank 20b according to the hot water discharge.

The reforming water tank 5 is for recovering the condensed water generated from the exhaust gas discharged from the fuel cell 1, and in the present embodiment, the condensed water is recovered from the exhaust gas after the heat recovery by the heat exchanger 2. It has become. Further, in the present embodiment, the condensed water supplied to the reforming water tank 5 is purified by the water purifier 4, and specifically, the condensed water recovery path 41 from the exhaust gas flowing through the exhaust gas discharge path 22. The condensed water is recovered in the water purifier 4 via the water purifier 4, and the condensed water purified by the water purifier 4 is recovered in the reformed water tank 5 via the condensed water recovery path 51. Further, the condensed water stored in the reforming water tank 5 (and the water supplied from the water supply unit 6) can be supplied to the reformer 12 via the water supply path 52 by the operation of the pump 53. There is. Further, the reformed water tank 5 is provided with a water level detector 54 so that the water level in the reformed water tank 5 can be detected.

Further, water can be supplied to the reformed water tank 5 from the water supply unit 6 independently of the condensed water. Specifically, the water supply unit 6 is designed to supply tap water, and as a water injection operation, the operation control unit opens the valve 62 in response to the water injection command to supply make-up water from the water supply unit 6. Water is supplied through the road 61. Then, the water injection amount from the start of the water injection operation is measured by the flow meter 63, and the water injection is performed until the water injection amount reaches a predetermined target water injection amount. Further, since tap water is more likely to have more impurities than condensed water, the water supply unit 6 makes it possible to supply water to the reforming water tank 5 via the water purifier 4 in the water injection operation, and the impurities. The water after the water is removed is supplied to the reforming water tank 5.

The DC voltage of the DC power generated by the fuel cell 1 is converted into an AC voltage in the following power conversion device 70 in order to be interconnected with the commercial power of the commercial power system 30.

(3) Power conversion device Next, the power conversion device 70 will be described.
Here, in the present embodiment, when another electronic device is connected to the power conversion device 70 that converts the electric power generated by the fuel cell 1, a technique capable of suppressing the influence on the electronic device such as noise and flicker of lighting. The purpose is to get. Therefore, first, the electric circuit (FIG. 3) in which only the power conversion device 70 is connected between the fuel cell 1 and the commercial power system 30 and no other electronic devices are connected, and the power conversion device 70 is fueled. It is examined whether or not problems such as noise and flicker of lighting occur in an electric circuit (FIG. 4) to which an electronic device other than the battery 1 is connected.

(3-1) Examination of problems such as noise and flicker of lighting First, using FIG. 3, noise and noise and an electric circuit in which only the power conversion device 70 is connected between the fuel cell 1 and the commercial power system 30. Examine whether or not problems such as lighting flicker have occurred. FIG. 3 is an electric circuit diagram in which only a power conversion device is connected between the fuel cell and the commercial power system. The power conversion device 70 uses the DC voltage of the DC power generated by the fuel cell system 20 as the commercial power of the commercial power system 30 so that the fuel cell system 20 and the commercial power system 30 can be interconnected. Convert to AC voltage.

The power conversion device 70 is connected to the anode 15 and the cathode 16 of the fuel cell 1, and includes a booster circuit 71, an inverter circuit 72, and a smoothing circuit 73. The booster circuit 71, the inverter circuit 72, and the smoothing circuit 73 form a closed circuit. In FIG. 3, one end of the capacitor C1 and the output end of the reactor 73a are connected by the node N1, and the other end of the capacitor C1 and the output end of the reactor 73b are connected by the node N2. The booster circuit 71, the inverter circuit 72, and the smoothing circuit 73 side from the node N1 and the node N2 are in the closed circuit, and the side opposite to the closed circuit from the node N1 and the node N2 is outside the closed circuit.
The booster circuit 71 boosts the DC voltage of the DC power of the fuel cell 1. The inverter circuit 72 converts the DC voltage boosted by the booster circuit 71 into an AC voltage. The smoothing circuit 73 removes noise of the AC voltage converted by the inverter circuit 72.

As shown in FIG. 3, the inverter circuit 72 includes switching elements 72a to 72d. The switching elements 72a to 72d are composed of, for example, an IGBT (Insulated Gate Bipolar Transistor). In addition, the switching elements 72a to 72d may be composed of switching transistors such as MOSFETs (metal-oxide-semiconductor field-effect transistors). A freewheeling diode D7a to D7d is connected between the collector terminal and the emitter terminal in each of the switching elements 72a to 72d.

The switching element 72a and the switching element 72b are connected in series between a pair of output ends of the booster circuit 71. That is, the collector terminal of the switching element 72a is connected to one end of the output end of the booster circuit 71, the emitter terminal of the switching element 72a and the collector terminal of the switching element 72b are connected, and the emitter terminal of the switching element 72b is the booster circuit 71. It is connected to the other end of the output end.

Similarly, the switching element 72c and the switching element 72d are connected in series between the pair of output ends of the booster circuit 71. That is, the collector terminal of the switching element 72c is connected to one end of the output end of the booster circuit 71, the emitter terminal of the switching element 72c and the collector terminal of the switching element 72d are connected, and the emitter terminal of the switching element 72d is the booster circuit 71. It is connected to the other end of the output end.

The smoothing circuit 73 includes a reactor 73a, a reactor 73b, and a capacitor C1. One end of the reactor 73a is connected between the emitter terminal of the switching element 72a and the collector terminal of the switching element 72b, and the other end is connected to one end of the capacitor C1. The reactor 73b is connected between the emitter terminal of the switching element 72c and the collector terminal of the switching element 72d, and the other end is connected to the other end of the capacitor C1. The reactor 73a, the reactor 73b, and the capacitor C1 function as a noise reduction filter that smoothes the AC voltage output from the inverter circuit 72, that is, removes the noise of the AC voltage.

Such a power conversion device 70 operates as follows. The DC voltage of the DC power generated by the fuel cell 1 is boosted by the booster circuit 71. In the inverter circuit 72, the first loop when the switching element 72a and the switching element 72d are on and the switching element 72b and the switching element 72c are off, and the switching element 72a and the switching element 72d are off, and the switching element 72b and It operates by switching to the second loop when the switching element 72c is on. When the boosted DC voltage is input to the inverter circuit 72, the boosted DC voltage is converted into an AC voltage by switching between the first loop and the second loop at a predetermined switching frequency. The AC voltage output from the inverter circuit 72 is introduced into the smoothing circuit 73. As described above, the generated power generated by the fuel cell system 20 and the commercial power of the commercial power system 30 can be interconnected via the power conversion device 70 described above.

As shown in FIG. 3, the AC voltage P1 whose voltage change is weakened through the reactor 73a of the smoothing circuit 73 is composed of the generated waveform W1 and the harmonic component W2. The generated waveform W1 is a waveform that the power conversion device 70 is about to generate, and is, for example, a waveform having a frequency of 50 Hz or 60 Hz of commercial power. Further, the harmonic component W2 is a component generated in synchronization with the switching frequency.

In the case of the electric circuit diagram shown in FIG. 3, the power conversion device 70 is connected between the fuel cell 1 and the commercial power system 30, and no other electronic device is connected to the power conversion device 70. In this case, the circuit including the fuel cell 1 and the power conversion device 70 is one circuit. Therefore, due to the presence of the capacitor C1, most of the harmonic component W2 of the AC voltage P1, for example, approximately 100% of the harmonic component W2 advances to the reactor 73b side and returns to the power conversion device 70. That is, the AC voltage P1 containing approximately 100% of the harmonic component W2 returns to the power converter 70, and the AC voltage P2 containing almost no harmonic component W2 is the booster circuit 71, the inverter circuit 72, and the smoothing circuit. It is output to the outside from the closed circuit consisting of 73, and is output to the commercial power system 30.
The AC voltage P1 is a voltage that has passed through the reactor 73a and returns to the power conversion device 70 as described above, but the voltage that has passed through the reactor 73b also returns to the power conversion device 70 as described above.

Next, an electric circuit in which an electronic device other than the fuel cell 1 is connected to the power conversion device 70 shown in FIG. 3 will be examined. Here, examples of other electronic devices include home appliances such as an air conditioner 10c, lighting 10d, television 10e and refrigerator 10f shown in FIG. 1, and other power generation devices such as a solar power generation device. FIG. 4 is an electric circuit diagram in which a photovoltaic power generation device is connected as another electronic device to a power conversion device connected between a fuel cell and a commercial power system.

In FIG. 4, the configuration in which the power conversion device 70 is connected to the anode 15 and the cathode 16 of the fuel cell 1 is the same as in FIG. In the electric circuit diagram of FIG. 4, unlike FIG. 3, a photovoltaic power generation device 90 is connected to the power conversion device 70 as another electronic device. Further, the power conversion device 70 is connected to a power conversion device 80 that converts the DC voltage of the DC power generated by the solar power generation device 90 into the AC voltage of the commercial power of the commercial power system 30. The power conversion device 80 is connected to the photovoltaic power generation device 90 and includes a booster circuit 81, an inverter circuit 82, and a smoothing circuit 83. The inverter circuit 82 includes switching elements 82a to 82d and freewheeling diodes D8a to D8d. The smoothing circuit 83 includes a reactor 83a, a reactor 83b, and a capacitor C2. Since the booster circuit 81, the inverter circuit 82, and the smoothing circuit 83 have the same configuration as the booster circuit 71, the inverter circuit 72, and the smoothing circuit 73 of the power conversion device 70, the description thereof will be omitted.

As in FIG. 3, the booster circuit 71, the inverter circuit 72, and the smoothing circuit 73 form a closed circuit. Further, one end of the capacitor C1 and the output end of the reactor 73a are connected by the node N1, and the other end of the capacitor C1 and the output end of the reactor 73b are connected by the node N2. The booster circuit 71, the inverter circuit 72, and the smoothing circuit 73 side from the node N1 and the node N2 are in the closed circuit, and the side opposite to the closed circuit from the node N1 and the node N2 is outside the closed circuit.

Similar to FIG. 3, in FIG. 4, the DC voltage generated by the fuel cell 1 is converted into an AC voltage via the booster circuit 71 and the inverter circuit 72 and input to the smoothing circuit 73. The AC voltage P1 that has passed through the reactor 73a is composed of a generated waveform W1 and a harmonic component W2. Here, in the electric circuit of FIG. 4, a solar power generation device 90 is connected to the power conversion device 70 as another electronic device, and the fuel cell 1, the power conversion device 70, the power conversion device 80, and the solar power generation device 90 are connected. The circuit including is one circuit. In this circuit, the capacity of the capacitor C1 of the power conversion device 70 on the fuel cell 1 side is generally smaller than the capacity of the capacitor C2 of the power conversion device 80 on the solar power generation device 90 side, which is another electronic device. By reducing the capacity of the capacitor C1 on the fuel cell 1 side in this way, for example, the cost of the fuel cell system 20 can be reduced. This also applies when other electronic devices such as home appliances other than the photovoltaic power generation device 90 are connected to the power conversion device 70. That is, the capacity of the capacitor C1 on the fuel cell 1 side is smaller than the capacity of the capacitor C2 on the side of other electronic devices such as home appliances.

As described above, when the circuit including the fuel cell 1, the power conversion device 70, the power conversion device 80, and the solar power generation device 90 is configured in one circuit, the capacity of the capacitor C1 <the capacity of the capacitor C2. Therefore, the AC voltage is applied to the capacitor C2 more than the capacitor C1. Therefore, due to the presence of the capacitor C2, for example, 80% of the harmonic component W2 of the AC voltage P1 is output to the outside of the closed circuit, and the remaining 20% of the harmonic component W2 of the AC voltage P1 advances to the reactor 73b side. Return to the power converter 70. That is, the AC voltage containing about 20% of the harmonic component W2 of the AC voltage P1 returns to the power converter 70, and the AC voltage P3 containing about 80% of the harmonic component W2 of the AC voltage P1 is a booster circuit. It is output to the outside from a closed circuit including 71, an inverter circuit 72, and a smoothing circuit 73, and is output to the commercial power system 30.

This AC voltage P3 is interconnected with the commercial power of the commercial power system 30, becomes an AC voltage P4, and is applied to the capacitor C2 on the side of the photovoltaic power generation device 90. The AC voltage P4 includes a harmonic component W2 of the AC voltage P4, which is composed of, for example, about 80% of the harmonic component W2 of the AC voltage P1. This AC voltage P4 is applied to the capacitor C2 and returns to the power conversion device 70 on the fuel cell 1 side. Then, in the process of returning to the fuel cell 1 side, the AC voltage P4 is applied to the reactor 84 on the solar power generation device 90 side, which is another electronic device. As described above, the AC voltage P4 contains the harmonic component W2 of the AC voltage P4, which is composed of, for example, about 80% of the harmonic component W2 of the AC voltage P1, so that the harmonic component W2 of the AC voltage P4 is included. It is applied to the reactor 84. Therefore, the reactor 84 is magnetostricted by the harmonic component W2, that is, the shape is distorted due to the influence of the harmonic component W2 of the AC voltage P4, and the reactor 84 generates an abnormal noise. Here, the reactor 84 is affected by the harmonic component W2 of the AC voltage P4, but electronic components other than the reactor 84 of other electronic devices are also affected by the harmonic component W2 of the AC voltage P4 and make abnormal noise. Can occur. When, for example, the reactor 84, which is an electronic component of another electronic device, generates an abnormal noise in this way, a noise problem occurs. Further, when the other electronic component is a component related to lighting, the component is affected by the harmonic component W2 of the AC voltage P4, which causes a problem such as flicker of lighting.

(3-2) Configuration for Suppressing Problems such as Noise and Illumination Flicker In the present embodiment, in order to suppress the above-mentioned problems such as noise and lighting flicker, the switching elements 72a to 72d in the power conversion device 70 are used. Control the switching frequency. Before control, the switching frequency is assumed to be a relatively low frequency, for example, within the audible range.
FIG. 5 is an electric circuit diagram of the power conversion device according to the embodiment. Specifically, the power conversion device 70 according to the present embodiment determines whether or not the AC voltage contains a harmonic component in addition to the booster circuit 71, the inverter circuit 72, the smoothing circuit 73, and the like. A unit 101 and a frequency control unit 103 that controls the switching frequency of the inverter circuit 72 are further provided.

As shown in FIG. 5, the harmonic component determination unit 101 monitors the power waveform of the AC voltage P3 output to the outside from the closed circuit including the booster circuit 71, the inverter circuit 72, and the smoothing circuit 73. Then, the harmonic component determination unit 101 determines whether or not the harmonic component W2 other than the generated waveform W1 is included in the power waveform of the AC voltage P3. Further, when the harmonic component determination unit 101 detects the harmonic component W2, it determines whether or not the frequency of the detected harmonic component W2 is equal to or less than the harmonic component threshold Th (threshold value). The harmonic component threshold Th is defined, for example, by the frequency at the boundary between the inside of the audible range and the outside of the audible range. That is, the harmonic component determination unit 101 determines whether or not the harmonic component W2 is a frequency component in the audible range. Then, the harmonic component determination unit 101 outputs the determination result to the frequency control unit 103.

More specifically, an example of the operation in the harmonic component determination unit 101 will be described. For example, the harmonic component determination unit 101 Fourier transforms the power waveform of the AC voltage P3 to generate the waveform W1 and other harmonic components W2. Separate into. At this time, the generated waveform W1 is a waveform having a peak at 50 Hz or 60 Hz. The harmonic component W2 is composed of a combination of a plurality of harmonic components. Therefore, the harmonic component W2 has a plurality of peaks at a predetermined frequency, and the harmonic component determination unit 101 detects the harmonic component having the largest peak, that is, the dominant harmonic component as the harmonic component W2. Since the harmonic component W2 is generated in synchronization with the switching frequency, the harmonic component having substantially the same frequency as the switching frequency is dominant in the harmonic component composed of a plurality of combinations. Then, the harmonic component determination unit 101 compares the detected frequency of the harmonic component W2 with the harmonic component threshold Th.

As a result of the determination by the harmonic component determination unit 101, when the AC voltage P3 contains the harmonic component W2 having a harmonic component threshold Th or less, the frequency control unit 103 currently sets the switching frequency of the switching elements 72a to 72d. It is controlled to be higher than the switching frequency of. The predetermined value is not particularly limited, but is 5 kHz or the like, and the switching frequency after increasing the predetermined value is, for example, 20 kHz, 25 kHz, 30 kHz or the like.
By increasing the switching frequency in this way, the frequency of the harmonic component W2 generated in synchronization with the switching frequency also increases. The rising switching frequency is such that when the harmonic component W2 affected by the switching frequency flows into an electronic component of another electronic device, the abnormal noise generated by the other electronic component does not become noise. For example, the switching frequency after the rise is a frequency close to the outside of the audible range, and more preferably a frequency outside the audible range. Examples of frequencies outside the audible range include 20 kHz or higher. Such adjustment of the switching frequency is also effective in suppressing flicker of lighting.

As described above, when the AC voltage P3 output to the outside from the closed circuit of the power conversion device 70 contains the harmonic component W2, the switching frequency of the inverter circuit 72 is controlled to be increased by a predetermined value. Since the harmonic component W2 is generated in synchronization with the switching frequency of the inverter circuit 72, increasing the switching frequency also increases the frequency of the harmonic component W2. As a result, the frequency of the abnormal sound generated from another electronic device due to the influence of the harmonic component W2 approaches the outside of the audible range or the outside of the audible range. Therefore, the abnormal noise becomes hard to hear, and the noise problem can be suppressed. Further, by increasing the frequency of the harmonic component W2, the flicker interval of the illumination is narrowed, and the problem of flicker can be suppressed.

Further, the power conversion device 70 controls the switching frequency to suppress the generation of noise and the flickering of lighting due to abnormal noise of other electronic devices connected to the power conversion device 70. Therefore, it is not necessary for other electronic devices to be equipped with a device for suppressing noise generation due to abnormal noise and flicker of lighting, and further, it is necessary for other electronic devices to control for noise suppression and flicker suppression. There is no. Therefore, even when a new electronic device having no device and control for noise suppression, flicker suppression, etc. is connected to the power conversion device 70, the power conversion device 70 causes abnormal noise due to the new electronic device. It is possible to suppress the generation of noise and the flickering of lighting. This makes it possible to improve the degree of freedom in connecting a new electronic device to the power conversion device 70.

As a result of the determination by the harmonic component determination unit 101, when the AC voltage P3 does not include the harmonic component W2, or when the AC voltage P3 contains the harmonic component W2 but exceeds the harmonic component threshold Th. The frequency control unit 103 maintains the switching frequency at the current frequency.

Even after the frequency control unit 103 controls to increase the switching frequency, the harmonic component determination unit 101 monitors the power waveform of the AC voltage P3 output to the outside of the closed circuit, and the AC voltage P3 is similarly described above. It is determined whether or not the power waveform of the above contains a harmonic component W2 other than the generated waveform W1. When the harmonic component W2 is detected, the harmonic component determination unit 101 determines whether or not the frequency of the detected harmonic component W2 is equal to or less than the harmonic component threshold Th (threshold value). As a result of the determination by the harmonic component determination unit 101, when the AC voltage P3 contains the harmonic component W2 having a harmonic component threshold Th or less, the frequency control unit 103 again determines the switching frequency to be higher than the current switching frequency. Control to increase only the value.

On the other hand, when the harmonic component determination unit 101 does not detect the harmonic component W2, or when the frequency control unit 103 determines that the frequency of the harmonic component W2 exceeds the harmonic component threshold Th. The frequency control unit 103 lowers the switching frequency by a predetermined value. In this case, the power conversion efficiency of the power conversion device 70 can be improved by lowering the switching frequency.
The predetermined value for increasing the switching frequency and the predetermined value for decreasing the switching frequency may be different or the same. Further, the width of the predetermined value may be constant or different.

(4) Frequency control flow for suppressing noise and flicker of lighting Next, the present embodiment including a harmonic component determination unit 101 and a frequency control unit 103 for suppressing flicker of noise and lighting. The frequency control flow in the power converter 70 will be described. FIG. 6 is an example of a flowchart showing a frequency control flow in the power conversion device according to the embodiment.

Step S1: The harmonic component determination unit 101 monitors the power waveform of the power conversion device 70, that is, the AC voltage P3 output to the outside from the closed circuit.
Step S2: The harmonic component determination unit 101 determines whether or not the harmonic component W2 is included in the power waveform of the AC voltage P3. When the harmonic component determination unit 101 detects the harmonic component W2 (Yes in step S2), the process proceeds to step S3. On the other hand, when the harmonic component determination unit 101 does not detect the harmonic component W2 (No in step S2), the harmonic component determination unit 101 continues to monitor the AC voltage P3 in step S1.
Step S3: The harmonic component determination unit 101 compares the frequency of the harmonic component W2 with the harmonic component threshold Th, and determines that the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th (Yes in step S3). , Step S4. On the other hand, when the harmonic component determination unit 101 determines that the frequency of the harmonic component W2 exceeds the harmonic component threshold Th (No in step S3), the harmonic component determination unit 101 continues to monitor the AC voltage P3 in step S1.

Step S4: The frequency control unit 103 controls the switching frequencies of the switching elements 72a to 72d so as to be higher than the current switching frequency by a predetermined value.
Step S5: The harmonic component determination unit 101 continues to monitor the power waveform of the AC voltage P3.
Step S6: The harmonic component determination unit 101 determines whether or not the harmonic component W2 is included in the power waveform of the AC voltage P3. When the harmonic component determination unit 101 detects the harmonic component W2 (Yes in step S6), the process proceeds to step S7. On the other hand, if the harmonic component determination unit 101 does not detect the harmonic component W2 (No in step S6), the process proceeds to step S8.

Step S7: The harmonic component determination unit 101 compares the frequency of the harmonic component W2 with the harmonic component threshold Th, and determines that the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th (Yes in step S7). The process proceeds to step S4, and the frequency control unit 103 further raises the switching frequency. On the other hand, when the frequency control unit 103 determines that the frequency of the harmonic component W2 is larger than the harmonic component threshold value Th (No in step S7), the process proceeds to step S8.
Step S8: The frequency control unit 103 controls the switching frequency to be lowered by a predetermined value from the current switching frequency, such as returning the switching frequency to the initial value. Even after the switching frequency is lowered, the harmonic component determination unit 101 continues to monitor the power waveform of the AC voltage P3 in step S1.

[Another Embodiment]
(1) In the above embodiment, one harmonic component threshold Th and the frequency of the harmonic component are compared, and when the frequency of the harmonic component becomes equal to or less than the harmonic component threshold Th, the switching of the power conversion device 70 is performed. Increase the frequency. However, the switching frequency may be controlled based on not only one harmonic component threshold value but also a plurality of harmonic component threshold values.
For example, the harmonic component threshold includes a first harmonic component threshold Th1 and a second harmonic component threshold Th2 larger than the first harmonic component threshold Th1. Further, the first set frequency H1 described later is larger than the second set frequency H2.

When the harmonic component determination unit 101 detects the harmonic component W2 in the power waveform of the AC voltage P3, the detected harmonic component W2 is larger than the first harmonic component threshold Th1 and equal to or less than the second harmonic component threshold Th2. The frequency control unit 103 sets the switching frequency to the second set frequency H2. When the detected harmonic component W2 is equal to or less than the first harmonic component threshold Th1, the frequency control unit 103 sets the switching frequency to the first set frequency H1.
By gradually increasing the switching frequency from the second set frequency H2 to the first set frequency H1 as the frequency of the harmonic component W2 becomes smaller, the switching frequency can be set to a frequency closer to or outside the audible range in a stepwise manner. If the switching frequency can be adjusted step by step in this way, the switching frequency is controlled so that it does not become excessively high, and problems such as noise and flicker of lighting due to the influence of harmonic components synchronized with the switching frequency are suppressed. At the same time, it is possible to suppress a decrease in the power conversion efficiency of the power conversion device 70.

(2) In the above embodiment, when the harmonic component determination unit 101 detects the harmonic component W2 at the AC voltage P3 and the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th, the frequency control unit 103. Control to increase the switching frequency. However, when the harmonic component W2 having a harmonic component threshold value of Th or less is detected, a user such as a serviceman may be notified and the switching frequency to be set may be accepted from the user.
FIG. 7 is an electric circuit diagram of a power conversion device that can accept a switching frequency from a user. The power conversion device 70 of FIG. 7 includes a notification unit 105 and a setting reception unit 107 in addition to the power conversion device 70 of FIG. Since the configurations of the other power conversion devices 70 are the same as those in the embodiment, the description thereof will be omitted.

The control of the switching frequency in the power conversion device of FIG. 7 will be described below.
When the harmonic component determination unit 101 detects the harmonic component W2 at the AC voltage P3 and determines that the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th, the notification unit 105 raises the switching frequency. , Notifies the user to input a set frequency H higher than the current switching frequency. The setting receiving unit 107 receives the input of the set frequency H from the user. At this time, the setting reception unit 107 accepts the set frequency H only when the input set frequency H is higher than the current switching frequency, and when the input set frequency H is equal to or lower than the current switching frequency, the user newly receives the set frequency H. Prompt for input of the set frequency H. The frequency control unit 103 changes the current switching frequency to the accepted set frequency H.

Here, examples of the member for inputting the set frequency H by the user include, but are not limited to, the knob adjusting member 75. FIG. 8 is a schematic view of a power conversion device provided with a knob adjusting member. The knob adjusting member 75 is, for example, a rotary knob, and the user can input a desired set frequency in the range of, for example, 0 to 40 kHz by rotating the knob adjusting member 75.

Further, even after the current switching frequency is changed to a higher set frequency H, the harmonic component determination unit 101 monitors the AC voltage P3. When the harmonic component determination unit 101 no longer detects the harmonic component W2 at the AC voltage P3, or determines that the frequency of the detected harmonic component W2 is larger than the harmonic component threshold Th, the notification unit 105 determines. In order to lower the switching frequency, the user is notified to input a set frequency H lower than the current switching frequency. The setting receiving unit 107 receives the input of the set frequency H from the user. At this time, the setting reception unit 107 accepts the set frequency H only when the input set frequency H is lower than the current switching frequency, and when the input set frequency H is equal to or higher than the current switching frequency, the user newly receives the set frequency H. Prompt for input of the set frequency H. The frequency control unit 103 changes the current switching frequency to the accepted set frequency H. In the above case, the power conversion efficiency of the power conversion device 70 can be improved by lowering the switching frequency.

In the above case, the setting receiving unit 107 may receive input of a plurality of setting frequencies H having different frequency magnitudes step by step from the user. For example, when the user receives a notification from the notification unit 105, the user first inputs the first set frequency H1 to the setting reception unit 107. The first set frequency H1 is assumed to be higher than the current switching frequency. Even if the switching frequency is set by the first set frequency H1, if the harmonic component determination unit 101 determines that the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th, the notification unit 105 is further higher. Notify the user to input the set frequency H2. Therefore, the user inputs a second set frequency H2 larger than the first set frequency H1 to the setting reception unit 107 to adjust the switching frequency. If the switching frequency can be adjusted step by step in this way, the switching frequency is controlled so as not to become excessively high, and power conversion is performed while suppressing problems such as noise and flicker of lighting due to the influence of the harmonic component W2. It is possible to suppress a decrease in the power conversion efficiency of the device 70.

(3) In the above embodiment, when the harmonic component determination unit 101 detects the harmonic component W2 at the AC voltage P3 and the frequency of the harmonic component W2 is equal to or less than the harmonic component threshold Th, the frequency control unit 103. Control to increase the switching frequency.
However, the power conversion device 70 may not be provided with the harmonic component determination unit 101. For example, when another electronic device is connected to the power conversion device 70 and the user detects an abnormal noise from the other electronic device, the frequency control unit 103 changes the switching frequency to the set frequency received from the user. May be good.

(4) In the above embodiment, when the frequency of the harmonic component W2 included in the power waveform of the AC voltage P3 is equal to or less than the harmonic component threshold Th (threshold), the switching frequency of the switching elements 72a to 72d is increased. Control. However, when the harmonic component W2 is included in the power waveform of the AC voltage P3, the frequency control unit 103 controls to immediately raise the switching frequency without comparing with the harmonic component threshold Th (threshold). May be good.

(5) In the above embodiment, the fuel cell system 20 is taken as an example as a power generation system installed in each home 10. However, the power generation system is not limited to this, and may be, for example, a power generation system such as wind power or solar power.

(6) In the above embodiment, the harmonic component determination unit 101 and the frequency control unit 103 are separate functional units, but these are integrated functional units, and these functional units are the harmonic component determination unit 101 and the frequency. The processing of each of the control units 103 may be performed as a unit.

(7) In the above embodiment, the power conversion device 70 includes a booster circuit 71. However, the power conversion device 70 does not have to include the booster circuit 71.
The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

1: Fuel cell 20: Fuel cell system 30: Commercial power system 70: Power conversion device 72: Inverter circuit 80: Power conversion device 101: Harmonic component determination unit 103: Frequency control unit 103a: Notification unit 103b: Setting reception unit 103c : Change unit 105: Storage unit W1: Generated waveform W2: Harmonic component

Claims (14)

An inverter circuit that has a switching element that converts the DC voltage of the DC power generated by the power generation device into an AC voltage and forms a closed circuit.
A harmonic component determination unit that determines whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the harmonic component determination unit determines that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains the harmonic component, the switching frequency of the switching element is set to a predetermined value. Equipped with a frequency control unit to raise
The case where it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component is the case where another electronic device is connected to the power conversion device. A power conversion device that is at least one of a case where another electronic device is affected by the harmonic component and generates an abnormal sound having a frequency in the audible range and a case where a light flicker is generated . The frequency control unit raises the switching frequency when the frequency of the harmonic component determined to be included in the AC voltage output to the outside from the closed circuit of the inverter circuit is equal to or lower than the threshold value, according to claim 1. The power converter described. The power conversion device according to claim 1 or 2, wherein the frequency control unit raises the switching frequency to a frequency outside the audible range. When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit no longer contains the harmonic component after the switching frequency is increased, the frequency control unit may use the frequency control unit. The power conversion device according to any one of claims 1 to 3, wherein the switching frequency is lowered by a predetermined value. When it is determined that the power waveform of the AC voltage contains a harmonic component, a notification unit that notifies the switching frequency to be increased by a predetermined value and a notification unit.
After the notification by the notification unit, the setting reception unit that accepts the setting of the setting frequency that can raise the switching frequency by a predetermined value, and the setting reception unit.
Further prepare
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the frequency control unit receives the switching frequency at the setting reception unit. The power conversion device according to claim 1, which raises the frequency to a set frequency. The power conversion device according to claim 5, wherein the setting receiving unit is configured to be able to receive the setting of the set frequency step by step. After the switching frequency is increased, when the harmonic component determination unit determines that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit no longer contains the harmonic component, the notification unit Notifies the switching frequency to be lowered by a predetermined value,
The setting receiving unit receives a setting of a setting frequency capable of lowering the switching frequency by a predetermined value, and receives the setting.
The power conversion device according to claim 5 or 6, wherein the frequency control unit lowers the switching frequency to a set frequency received by the setting reception unit. When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the setting frequency is set so that the switching frequency can be increased by a predetermined value. Setting reception unit that accepts
The power conversion device according to claim 1, wherein the frequency control unit raises the switching frequency to a set frequency received by the setting reception unit. The power conversion device according to claim 8, wherein the setting receiving unit is configured to be able to receive the setting of the set frequency step by step. A power conversion method in a power conversion device having a switching element and an inverter circuit forming a closed circuit.
A step of converting the DC voltage of the DC power generated by the power generation device into an AC voltage by switching the switching element.
A step of determining whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, a step of increasing the switching frequency of the switching element by a predetermined value is provided . ,
The case where it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component is the case where another electronic device is connected to the power conversion device. A power conversion method that is at least one of the cases where another electronic device is affected by the harmonic component to generate an abnormal sound having an audible frequency and causes light flicker . When it is determined that the power waveform of the AC voltage contains a harmonic component, a step of notifying the switching frequency to be increased by a predetermined value and a step of notifying the user to increase the switching frequency by a predetermined value.
After the notification, the step of accepting the setting of the set frequency that can raise the switching frequency by a predetermined value, and
Further prepare
The power conversion method according to claim 10, wherein in the step of increasing the switching frequency of the switching element by a predetermined value, the switching frequency is increased to the set frequency. When it is determined that the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the setting frequency is set so that the switching frequency can be increased by a predetermined value. With more steps to accept
The power conversion method according to claim 10, wherein in the step of increasing the switching frequency of the switching element by a predetermined value, the switching frequency is increased to the set frequency. An inverter circuit that has a switching element that converts the DC voltage of the DC power generated by the power generation device into an AC voltage and forms a closed circuit.
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, a frequency control unit that raises the switching frequency of the switching element by a predetermined value is provided.
A harmonic component determination unit that determines whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the power waveform of the AC voltage contains a harmonic component, a notification unit that notifies the switching frequency to be raised by a predetermined value and a notification unit.
After the notification by the notification unit, the setting reception unit that accepts the setting of the setting frequency that can raise the switching frequency by a predetermined value, and the setting reception unit.
Further prepare
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the frequency control unit raises the switching frequency to the set frequency received by the setting reception unit. Power converter. A power conversion method in a power conversion device having a switching element and an inverter circuit forming a closed circuit.
A step of converting the DC voltage of the DC power generated by the power generation device into an AC voltage by switching the switching element.
When the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit contains a harmonic component, the step of increasing the switching frequency of the switching element by a predetermined value and
Equipped with
A step of determining whether or not a harmonic component is included in the power waveform of the AC voltage output to the outside from the closed circuit of the inverter circuit, and
When the power waveform of the AC voltage contains a harmonic component, a step of notifying the switching frequency to be raised by a predetermined value and a step of notifying the user to raise the switching frequency by a predetermined value.
After the notification, the step of accepting the setting of the set frequency that can raise the switching frequency by a predetermined value, and
Further prepare
A power conversion method for raising the switching frequency to the set frequency in the step of raising the switching frequency of the switching element by a predetermined value.

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