WO2006033143A1

WO2006033143A1 - Solar photovoltaic power generation system and booster unit thereof

Info

Publication number: WO2006033143A1
Application number: PCT/JP2004/013822
Authority: WO
Inventors: Makoto Kasugai; Omi Nishi; Hirokazu Nakabayashi; Naoki Nishio
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2004-09-22
Filing date: 2004-09-22
Publication date: 2006-03-30
Also published as: JP4468372B2; JPWO2006033143A1

Abstract

In a solar photovoltaic power generation system, even when an abrupt no-load state occurs, the prevention of breakdown of a booster unit and/or a power conditioner can be ensured. A solar photovoltaic power generation system, which converts the DC outputs of its solar battery circuits to an AC output and which is interconnected with a commercial power system, comprises a booster unit (11) including booster circuits (20a,20b) that boost the DC voltages outputted from the plurality of solar battery circuits (10a,10b), and further comprises a power conditioner (12) that converts the DC powers outputted from the booster unit to an AC power. A control circuit (21a,21b) in each of the booster circuits includes an excessive voltage detection circuit (31a,31b) that determines whether the output voltage of the booster circuit exceeds a predetermined voltage value. The excessive voltage detection circuit included in the control circuit of one booster circuit outputs an excessive voltage detection signal to the control circuit of the other booster circuit.

Description

Specification

Photovoltaic power generation system and its boosting unit

Technical field

TECHNICAL FIELD [0001] The present invention relates to a photovoltaic power generation system and a boosting unit thereof, and in particular, raises the power generation voltage of a solar cell circuit within the input operation range of a power conditioner, and reduces the DC power of the solar cell circuit. The present invention relates to a photovoltaic power generation system that is converted into AC power and interconnected with commercial power, and a boosting unit thereof.

Background art

[0002] A solar power generation system converts DC power generated by a solar cell circuit into AC power using a power conditioner, and links with general commercial power supplied from an electric power company. It is a power generation system that regenerates to the grid side and supplies the insufficient power from the grid side. Conventionally, as a general configuration of this type of photovoltaic power generation system, for example, there is a configuration shown in Patent Document 1 below. FIG. 4 is a diagram illustrating an example of a boosting unit of a photovoltaic power generation system disclosed in Patent Document 1.

In FIG. 4, a booster unit 101 is a standard input unit 110 to which a solar cell circuit 100a that is one unit (hereinafter referred to as “solar cell circuit”) configured by connecting a plurality of solar cell modules in series is connected. And a step-up input unit 112 to which the solar cell circuit 100b is connected. The standard input unit 110 is an input unit that does not include a booster circuit, and that requires the number of series connected solar cell circuits that can be supplied without boosting the voltage within the input operation range of the power conditioner 102. is there. On the other hand, the boost input unit 112 is an input unit having a booster circuit, and is an input unit that boosts the voltage of the solar cell circuit to the operating range of the power conditioner by the booster circuit. The standard input unit 110 and the boost input unit 112 are each provided with a switch at each input stage, and the outputs are connected in the boost unit 101 to be grouped together and output to the power conditioner 102. The In the power conditioner 102, the DC power of the solar cell circuit output from the booster unit 101 is converted into AC power and connected to the commercial power system 104 to perform grid interconnection. In the boost unit shown in the figure, only two solar cell circuits (100a, 100b) are shown for simplification, Usually, more solar cell circuits may be input. In addition, the grid connection of the photovoltaic power generation system is an existing technology, so a detailed description is omitted.

[0004] The step-up input section 112 to which the solar cell circuit 100b is connected includes a main circuit including a rear tuttle, a switching element, a diode, a capacitor, and the like, and a switching element of the main circuit based on the input voltage Vs2 and the output voltage Vo2. A trip signal that generates and outputs a trip signal for tripping the input switch when an error occurs based on the output voltage Vo2 and the temperature T2 of the switching element detected by the temperature sensor. The number generator 1 16 is provided.

[0005] The booster circuit of the boost input unit 112 includes the number of series connection (nl) of solar cell circuits 100a that do not require a booster circuit and the number of series connections (n2) of solar cell circuits 100b that require a booster circuit. Is set as the target boost ratio α * (α * = nl / n2), and the boost ratio is controlled constant. The control circuit 1 14 of the boost input unit 1 12 compares the actual boost ratio a (a = Vo2 / Vs2), which is the ratio of the actual output voltage Vo2 and the input voltage Vs2, with the target boost ratio oc *. Control is performed to optimize the on / off time of the signal Sg2 transmitted to the switching element so that the error is reduced.

FIG. 5 is a diagram showing the voltage-power characteristics (hereinafter simply referred to as “VP characteristics”) of solar cell circuits having different numbers of series connections. Figure (a) shows the VP characteristics of the solar cell circuit 100a connected to the standard input unit 110 with a solid line (L1), and shows the solar cell circuit 100b connected to the boost input unit 112. The VP characteristic is shown by the broken line (L2). In Fig. 5 (a), the target step-up ratio (X *), which is expressed as the ratio of the number of solar cell circuits connected in series, is equal to the ratio of the open circuit voltages of each input section (VolZVo2). The voltage ratio (Vp lZVp2) at which the circuit achieves the maximum output is also approximately equal to the target boost ratio, so the VP characteristic of the solar cell circuit 100b connected to the boost input section 1 12 by constant boost ratio control is shown in the figure (b ), The maximum power point P2max of the boost input section 112 moves to P2max 'after boosting. At this time, the power conditioner 102 is the standard indicated by the thick line (L5). It operates at the Pmax point of the combined output characteristics of the input unit 1 10 and the boost input unit 1 1 2. It can extract the maximum power of the input power.As a result, the solar cell circuit of the standard input unit 1 10 100a and the solar cell circuit 100b of the step-up input section 112 are operated at the point where the respective output power becomes maximum. Ruko Togashi.

As described above, when the power conditioner 102 connected to the output of the boosting unit 101 is in an operating state, the boosting input unit 112 performs constant control of the target boosting ratio so that the target boosting ratio is constant. On the other hand, when the inverter 102 connected to the output of the booster unit is not in the operating state, the booster unit 101 is placed in a no-load state, and when the booster circuit of the booster input unit 112 performs the boosting operation, the output As the voltage increases, the input voltage of the inverter 102 exceeds the allowable input voltage range. The step-up input unit 112 detects such a state, and performs constant voltage control so that the output voltage of the step-up unit 101 falls within the allowable input voltage range of the power conditioner 102.

On the other hand, even if constant voltage control is performed, if the output voltage of booster unit 101 exceeds the allowable input voltage range of power conditioner 102, trip signal generator 116 of booster input unit 112 outputs output voltage Vo2 Is detected, and the breaker 121 of the input stage is tripped to open the line with the solar cell circuit, thereby preventing the booster unit 101 and the power conditioner 102 from being damaged.

[0009] In addition, when the switching element 122 of the boost input unit 112 causes a short-circuit failure or the like, and the short-circuit current of the solar cell circuit 100b continues to flow, a temperature sensor installed around the switching element 122 An abnormal temperature rise value is detected by the trip signal generator 1 16 due to 124, tripping the breaker 121 in the input stage to open the line with the solar cell circuit 100b, and the short-circuit current of the solar cell circuit 100b continues to flow. To prevent that.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-51571

Disclosure of the invention

Problems to be solved by the invention

[0011] By the way, when the booster circuit of the booster unit is operating stably, when the protection function of the power conditioner is activated and the power conditioner is stopped, a sudden no-load state is caused for the booster unit. As a result, the output voltage of the booster unit may exceed the upper limit within the input voltage range of the inverter. If this happens, the trip signal generator detects an overvoltage and trips the input circuit breaker of the booster circuit to open the line of the solar cell circuit. Is broken If this happens, the overvoltage cannot be detected, the output of the booster circuit becomes an abnormal overvoltage, and the booster unit and the power conditioner may be damaged.

[0012] Further, as described above, when the trip signal generation unit detects an overvoltage of the output voltage or an abnormal temperature rise value, the conventional boosting unit trips the input breaker of the boosting circuit to make a solar cell. The circuit lines were opened. However, in general, a switch (such as a magnetic contactor) that trips DC power, such as a solar cell circuit, is very expensive and has a relatively large part size. There was a problem that the size of the system also increased.

[0013] Further, the conventional boosting unit has a ratio of the number of series connection (nl) of solar cell circuits 100a that do not require a boosting circuit and the number of series connections (n2) of solar cell circuits 100b that require a boosting circuit. Set target boost ratio α * (α * = nl / n2) and perform constant boost ratio control, but target if the number of solar cell circuits 100b is one less than solar cell circuit 100a When the step-up ratio is small and the actual step-up ratio is almost equal to 1 due to variations in the solar cell circuit or the degree of sunlight irradiation, it is possible to generate annoying noise due to the intermittent operation of the step-up circuit. There was sex.

[0014] The present invention has been made in view of the above problems, and even when a sudden no-load state occurs in the booster unit, the booster unit and the power conditioner are damaged. The first object is to provide a photovoltaic power generation system and its boosting unit that can be reliably prevented.

[0015] Further, the present invention provides a photovoltaic power generation system and its boosting unit that can realize the same function without using an expensive switch for tripping DC power in a compact and low-cost manner. The purpose.

[0016] The third aspect of the present invention provides a photovoltaic power generation system and its boosting unit that can effectively prevent annoying noise that may occur due to intermittent operation of the boosting circuit. Objective.

Means for solving the problem

[0017] In order to solve the above-described problems and achieve the object, the photovoltaic power generation system according to the present invention converts the direct current output of the solar cell circuit into alternating current and connects with the commercial power system. In a power system, a step-up unit comprising a plurality of solar cell circuits and a step-up circuit that is connected to each of the plurality of solar cell circuits and boosts a DC voltage output from the connected solar cell circuits And a power conditioner that converts DC power output from the boosting unit into AC power, the boosting circuit based on the output voltage before boosting and the output voltage after boosting of the solar cell circuit output A control circuit that outputs a control signal that varies the boost ratio; and a switching element that varies the boost ratio based on the control signal output from the control circuit. The control circuit outputs the output of the boost circuit. When it is necessary to stop, the control signal output to the switching element is stopped.

[0018] According to the present invention, the boosting unit includes the booster circuit connected to each of the plurality of solar cell circuits, and the booster circuit includes the output voltage before boosting of the solar cell circuit output and the booster And a control circuit that outputs a control signal that varies the boost ratio based on the post-output voltage. The control circuit is a switching element for varying the boost ratio when the output of the boost circuit needs to be stopped. Stops the output of the control signal to.

The invention's effect

[0019] According to the photovoltaic power generation system according to the present invention, when the output of the booster circuit needs to be stopped, the control signal output to the switching element is stopped. There is no need to mount an expensive DC switch on the product and trip, reducing the cost of the device and reducing the size of the device. Brief Description of Drawings

FIG. 1 is a diagram showing a configuration of a photovoltaic power generation system including a boosting unit according to the present invention.

FIG. 2 is a diagram showing a configuration of each control circuit according to the present invention and a connection configuration between the control circuits.

[Fig. 3-1] Fig. 3-1 shows an example of the case where the control pulse width (G1) for turning on the switching element is extremely smaller than the control pulse width (G2) for turning off the switching element. is there.

[Fig. 3-2] Fig. 3-2 shows an example of the case where the control pulse width (G3) for turning on the switching element is extremely small compared to the control pulse width (G4) for turning off! It is. [FIG. 4] FIG. 4 is a diagram showing an example of a boosting unit of a photovoltaic power generation system that is effective in the prior art.

[FIG. 5] FIG. 5 is a diagram showing VP characteristics of solar cell circuits having different numbers of series connections. Explanation of symbols

[0021] 10a, 10b, 10c, 100a, 100b solar cell circuit

11, 101 Booster unit

12, 102 Inverter

14, 104 Commercial power system

18, 110 Standard input section

20a, 20b Booster circuit

21a, 21b, 114 control circuit

23 Rear Tuttle

24, 30, 122 Switching element

25 Diode

26, 27 capacitors

28, 124 Temperature sensor

29 Current sensor

31a, 31b Overvoltage detection circuit

32a, 32b Gate drive circuit

33a, 33b MCU

112 Boost input section

116 Trip signal generator

121 Breaker

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, embodiments of a photovoltaic power generation system and its boosting unit according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

[0023] FIG. 1 is a diagram showing a configuration of a photovoltaic power generation system including a boosting unit that works on the present invention. is there. In the boost unit shown in the figure, three solar cell circuits 1 Oa, 10b, and 10c are shown for simplification of the drawing, but the number of solar cell circuit inputs and the number of boost circuits can be expanded. Needless to say.

In FIG. 1, for example, solar cell circuits 10 a, 10 b, 10 c installed on a small space roof surface such as a dormitory roof are connected to the booster unit 11. The step-up unit 11 includes step-up circuits 20a and 20b connected to the solar cell circuits 10a and 10b, and a standard input unit 18 connected to the solar cell circuit 10c. The outputs of the booster circuits 20 a and 20 b and the standard input unit 18 are connected in the booster unit 11, gathered together, and output to the power conditioner 12. The inverter 12 includes a booster circuit for generating commercial grid voltage, an inverter circuit that converts the DC power of the solar cell circuit to AC power, a protection device for grid connection, etc. (all not shown) In addition to controlling the output of the solar cell circuit so that it operates at the maximum output operating point of the solar cell circuit (maximum power point tracking control), various processes for linking with the commercial power system 14 are performed.

Next, the configuration of the booster circuit according to the booster unit of the present invention using the booster circuit 20a will be described. In FIG. 1, the booster circuit 20a includes a main circuit including force such as a rear tuttle 23, a switching element 24, a diode 25, capacitors 26 and 27, a temperature sensor 28, and a current sensor 29, and a control circuit 21a. . The control circuit 21a includes the input voltage Vsl of the solar cell circuit 10a, the output voltage Vol of the booster circuit 20a, the current IL1 of the rear tuttle 23 when the switching element detected by the current sensor 29 is turned on, and the booster by the temperature sensor 28 Each signal of the ambient temperature T1 inside the unit is input. The control circuit 21a includes a sensor circuit to which these signals are input, a microcomputer (hereinafter referred to as “microcomputer”) (which is not shown in FIG. 1), which is the center of control. The microcomputer outputs the command value of the gate signal Sgl for turning on and off the switching elements of the main circuit, and generates a boosted output boosted to the target voltage value. In addition, the control circuits of each booster circuit are electrically connected to the output overvoltage protection signal Voerr and the input voltage value Vspmax when output to the outside is permitted by the microcomputer of the control circuit. .

Next, the operation of the boost unit 11 will be briefly described. Each boost of boost unit 11 The microcomputer in the voltage circuit constantly monitors the current operating point on the VP characteristics of each connected solar cell circuit, and controls the solar cell circuit so that this operating point becomes the maximum power point. . In this control, for example, the minute change amount (dPsZdVs) of the input power (Ps) with respect to the minute change amount of the input voltage (Vs) is calculated, and the minute change amount (dPsZdVs) is a value that is almost close to 0. It is possible to use a technique such as searching for. When the operation at the maximum power point of each solar cell circuit has been determined, the output voltage value of the solar cell circuit at this maximum power point (hereinafter referred to as the “maximum output operating voltage value”) is output, and each control circuit is The highest voltage value (hereinafter referred to as “the maximum value of the maximum output operating voltage value”) is set among the maximum output operating voltage values of the connected solar cell circuits. Each booster circuit sets a boost ratio with the maximum value of the maximum output operation voltage value as a target value, and performs a boost operation. However, if the maximum value of the maximum output operating voltage value is lower than the minimum voltage value at which the rated output of the inverter can be rated, each booster circuit will set the minimum input voltage value at which the rated output of the inverter can be output. A boost ratio is set as a target voltage, and a boost operation is performed.

[0027] In this way, normally, since the output voltage of the boost unit 11 boosted to the input voltage range in which the rated output of the power conditioner 12 can be output is input to the power conditioner 12, the power conditioner 12 The maximum power of each solar cell circuit can be extracted efficiently.

Next, consider the case where the power conditioner 12 connected to the booster unit 11 suddenly stops due to a protective operation or the like. At this time, the step-up unit 11 is placed in a no-load state, the output voltage of the step-up circuit performing the step-up operation rapidly increases, and the input voltage of the power conditioner 102 exceeds the allowable input voltage range. It will be. In such a state, in the above-described prior art, the trip signal generator of the booster circuit detects overvoltage, and trips the breaker of the booster circuit to open the line of the solar cell circuit. It was. However, if its own trip signal generator is faulty, overvoltage cannot be detected, and the output of the booster circuit becomes abnormal overvoltage, which may damage the booster unit and power conditioner. It was.

Therefore, in the present invention, the control circuit of each booster circuit is configured as shown in FIG. 2 to solve the above-mentioned problems. Here, FIG. 2 shows the configuration of each control circuit and the configuration of the present invention. It is a figure which shows the connection structure between each control circuit. In the control circuit shown in the figure, an overvoltage detection signal generated based on the output voltage of each booster circuit grouped in a series is transmitted not only to its own booster circuit but also to other booster circuits. ing.

Next, the configuration of the control circuit provided in the booster circuit of the booster unit of the present invention will be described. In FIG. 2, the control circuit 21a includes an overvoltage detection circuit 3la that detects the output voltage (Vol) of the output voltage of each booster circuit (that is, the booster unit 11) grouped together, and an overvoltage detection circuit 31a. A gate drive circuit 32a and a microcomputer 33a connected to the outputs are provided. The control signal of the microcomputer 33a is connected to the gate drive circuit 32a. In addition, the control circuit 21b, which is another booster circuit, is configured in the same manner as the control circuit 21a, and the overvoltage detection signals of the overvoltage detection circuits 31a and 31b of each control circuit are output not only to itself but also to other control circuits. It is configured to be

Next, the operation of the control circuit will be described. Since the outputs of the booster circuits 20a and 20b are grouped together in the output stage of the booster unit 11, they should output the same output value except for the transient state. They are shown as Vol and Vo2. In FIG. 2, when the overvoltage detection circuit 31a in the control circuit 21a that detects the output voltage Vol detects an overvoltage, a Vol overvoltage detection signal is output to the microcomputer 33a and also to the gate drive circuit 32a. At this time, a signal for stopping the switching operation of the switching element 24 is output from the gate drive circuit 32a. This Vol overvoltage detection signal is also output to the control circuit 21b of another booster circuit connected in hardware. According to the boost unit configured in this way, even if the overvoltage detection circuit 31a of the control circuit 21a fails, the control circuit of another normal boost circuit (in this embodiment, the control circuit 21b) Overvoltage detection circuit 31b) detects an overvoltage, and as indicated by the broken line, the operation of the switching element 24 of the booster circuit in which the overvoltage detection circuit has failed due to a signal from the overvoltage detection circuit 31b of the normal control circuit 21b. Can be stopped.

[0032] Fig. 3-1 is a diagram showing an example in which the control pulse width (G1) for turning on the switching element is not extremely smaller than the control pulse width (G2) for turning off the switching element. 3—2 is It is a figure which shows an example when the control pulse width (G3) which carries out on control of a switching element is extremely small compared with the control pulse width (G4) which carries out off control. In Fig. 3-1 and Fig. 3-2, the vertical axis represents the collector terminal of the switching element connected to the positive line of the solar cell circuit output and the emitter terminal of the switching element connected to the negative line. It is shown using the terminal voltage (V) between.

CE

[0033] As shown in Fig. 3-1, the switching element of the booster circuit changes its on / off ratio at a fixed frequency of about several tens of kHz during normal operation, that is, when an appropriate boost ratio is set. Switching operation is performed. On the other hand, as the step-up ratio becomes smaller, the on-time of the switching element becomes shorter. When there is almost no difference between the output voltage and the input voltage, the on-time within the basic switching period is almost zero. The control pulse width for turning on the switching element as shown in Fig. 5 becomes extremely smaller than the control pulse width for turning off the switching element. In this state, the switching operation of the switching element becomes an intermittent operation, and there is a possibility that annoying noise having a frequency component of about several kHz based on this intermittent operation is generated.

[0034] On the other hand, in such a situation, there is almost no difference between the maximum output operating voltage of the solar cell circuit input to the booster circuit and the maximum output point voltage of the target solar cell circuit. Therefore, there is no need to boost the voltage. Therefore, a predetermined threshold value is set for the boost ratio at which the boost operation is performed, and when the boost ratio is less than the predetermined threshold value, the booster circuit is stopped and the intermittent switching operation is not performed. Control. By performing such control, noise generated from the boosting unit can be prevented.

Note that this control concept can also be applied to the case where the booster circuit is stopped based on the temperature sensor output. In the conventional temperature control, the booster circuit detects the internal ambient temperature with a temperature sensor, and immediately stops the booster circuit when the internal ambient temperature reaches a predetermined temperature level. On the other hand, when the internal ambient temperature reaches a predetermined level, the current flowing through the main circuit of the booster circuit is reduced so that the internal ambient temperature does not rise above the predetermined temperature, instead of immediately stopping the booster circuit. The output power may be suppressed. By performing such control, the ON / OFF ratio of the switching element is varied and increased so that the internal ambient temperature does not rise above a predetermined temperature. What is necessary is just to reduce the electric current which flows into the main circuit of a pressure circuit, and to suppress output electric power. If the temperature rises even if the output power is suppressed, turn off the gate signal of the switching element and stop the booster circuit.

In this embodiment, the configuration of the booster circuit in which the switching control of the switching element changes the ON / OFF pulse width ratio using a fixed frequency of about several tens of kHz will be described as an example. However, it is needless to say that the present invention can be applied to a booster circuit having a configuration in which switching control of a variable frequency is performed.

[0037] As described above, according to the photovoltaic power generation system of this embodiment and its booster unit, the control circuit determines whether or not the output voltage of its own booster circuit has exceeded a predetermined voltage value. And an overvoltage detection circuit for detecting whether or not an overvoltage detection circuit included in the control circuit of one booster circuit outputs the detected overvoltage detection signal to the control circuit of another booster circuit. Therefore, it is possible to improve the reliability of protection against output overvoltage and to prevent damage due to overvoltage to the boost unit and the power conditioner to which the output is connected due to overvoltage.

[0038] Further, according to the photovoltaic power generation system and its boosting unit of this embodiment, when it is necessary to stop the output of the boosting circuit, the control signal output to the switching element is stopped. Therefore, it is possible to reduce the equipment cost and to reduce the scale of the equipment without the need for tripping by mounting an expensive DC switch on the product for protection by overvoltage detection.

[0039] Further, according to the photovoltaic power generation system and its boosting unit of this embodiment, the boosting operation of the boosting circuit is stopped when the boosting ratio set by itself is less than a predetermined threshold value. Therefore, intermittent switching of the booster circuit can be prevented, and noise caused by the switching can be prevented.

[0040] Further, according to the photovoltaic power generation system and its boosting unit of this embodiment, when the atmospheric temperature of the boosting circuit reaches a predetermined level, based on the control signal to the switching element. Reduce the current flowing through the booster circuit and control the booster circuit or the temperature inside the booster unit not to increase so as to secure the power generation time as much as possible. Therefore, the power utilization factor of the solar cell circuit can be increased.

Industrial applicability

As described above, the photovoltaic power generation system according to the present invention is useful as a clean power generation system that uses inexhaustible solar energy, and the boosting unit is useful as a component that realizes the photovoltaic power generation system. It is.

Claims

The scope of the claims

[1] A plurality of solar cell circuits, a booster unit including a booster circuit capable of boosting a DC voltage output from the plurality of solar cell circuits, and power for converting DC power output from the booster unit into AC power A photovoltaic power generation system comprising a conditioner, wherein the booster circuit is

A control circuit that outputs a control signal that varies a boost ratio based on an output voltage before boosting and an output voltage after boosting of the solar cell circuit output;

A switching element that varies a step-up ratio based on the control signal output from the control circuit force;

With

The solar power generation system, wherein the control circuit stops outputting a control signal to the switching element when the output of the booster circuit needs to be stopped.

[2] The solar power generation device according to claim 1, wherein the control circuit stops the boosting operation of the boosting circuit including the control circuit when the boosting ratio set by the control circuit is less than a predetermined threshold. Electric system.

[3] The control circuit further includes an overvoltage detection circuit that detects whether or not the output voltage of its booster circuit exceeds a predetermined voltage value.

2. The solar power generation system according to claim 1, wherein the overvoltage detection circuit included in the control circuit of one booster circuit outputs the detected overvoltage detection signal to the control circuit of another booster circuit.

[4] A plurality of solar cell circuits, a booster unit including a booster circuit capable of boosting a DC voltage output from the plurality of solar cell circuits, and power for converting DC power output from the booster unit into AC power A photovoltaic power generation system comprising a conditioner, wherein the booster circuit is

A switching element that varies a step-up ratio based on the control signal output from the control circuit force; With

The control circuit reduces the current flowing through the booster circuit based on a control signal to the switching element when the ambient temperature of the booster circuit including the control circuit reaches a predetermined level. Power generation system.

[5] In a booster unit of a photovoltaic power generation system that boosts a DC voltage output from a solar cell circuit to a predetermined level,

A booster circuit capable of boosting a DC voltage output from the solar cell circuit;

With

The boosting unit of a photovoltaic power generation system, wherein the control circuit stops outputting a control signal to the switching element when it is necessary to stop the output of the boosting circuit.

[6] The solar power generation device according to [5], wherein the control circuit stops the boost operation of the boost circuit including the control circuit when the boost ratio set by the control circuit is less than a predetermined threshold value. Booster unit for electric system.

[7] The control circuit further includes an overvoltage detection circuit that detects whether or not the output voltage of the booster circuit exceeds a predetermined voltage value.

6. The step-up unit of the solar power generation system according to claim 5, wherein the overvoltage detection circuit included in the control circuit of one booster circuit outputs the detected overvoltage detection signal to the control circuit of another booster circuit.

[8] In the step-up unit of the photovoltaic power generation system that boosts the DC voltage output from the solar cell circuit to a predetermined level,

A booster circuit capable of boosting a DC voltage output from the solar cell circuit; A control circuit that outputs a control signal that varies a boost ratio based on an output voltage before boosting and an output voltage after boosting of the solar cell circuit output;

With

The control circuit reduces the current flowing through the booster circuit based on a control signal to the switching element when the ambient temperature of the booster circuit including the control circuit reaches a predetermined level. Booster unit for power generation system.