Semiconductor breaker and photovoltaic power generation system

Abstract

To enable an efficient and stable usage of energy generated by a solar cell panel.SOLUTION: A semiconductor breaker for supplying power generated by a solar cell panel to an accumulator, a power system, or a load apparatus without using a power conditioner has a plurality of semiconductor switching elements connected between the solar cell panel and the accumulator, and a control unit for bringing at least predetermined semiconductor switching elements among the plurality of switching elements into an ON state or an OFF state according to a value of voltage, current, or temperature of a predetermined part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a semiconductor circuit breaker and a solar power generation system. [Background technology]

[0002] Generally, in a photovoltaic power generation system, the power generated by the solar panel is input to a power conditioner called a PCS (Power Conditioning System) or power conditioner, where it is converted from DC to AC in a DC / AC converter and supplied to load equipment and the power grid. In addition, the power required to operate the load equipment at night when no power is being generated is stored in a storage battery.

[0003] FIG. 7 shows an example of a typical solar power generation system.

[0004] 7, the power conditioner 100 is connected to a plurality of PV panels (solar panels) 11 constituting a solar cell 10, a storage battery 13, and also to load equipment and a power system (hereinafter referred to as the "power system, etc.") not shown. The power conditioner 100 has three power converters. Specifically, the power conditioner 100 has a DC / DC converter 121 used for MPPT (Maximum Power Point Tracking) control, a DC / DC converter 131 used for charge / discharge control of the storage battery 13, and a DC / AC converter (inverter) 14 used for DC / AC conversion between the power system, etc.

[0005] The energy generated by the PV panel 11 undergoes multiple power conversions in the power conditioner 100, resulting in significant losses. In particular, when the power stored in the storage battery 13 is used on the power grid side, even if each power converter has an excellent efficiency of 0.95, the power will be converted four times by the three power converters in the power conditioner 100, and only about 80% of the energy can be used at best. In reality, each power converter often operates under light load, which significantly reduces the conversion efficiency. For this reason, the current situation is that only about 60% of the generated energy can actually be used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7304532 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, because power conditioners cause large power losses, it is desirable to use some means or method to replace the power conditioner and make the most efficient use of the energy generated by the solar panel. In such cases, it is also desirable to take safety measures to prevent events such as overcharging the storage battery and overcurrent in the circuit.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a semiconductor circuit breaker and a solar power generation system that enable efficient and safe use of energy generated by a solar panel. [Means for solving the problem]

[0009] The semiconductor circuit breaker according to the embodiment is a semiconductor circuit breaker that enables power generated by a solar panel to be supplied to a storage battery, a power system, or a load device without using a power conditioner, and includes a plurality of semiconductor switching elements connected between the solar panel and the storage battery, and a control unit that turns on or off at least certain semiconductor switching elements among the plurality of semiconductor switching elements depending on the voltage, current, or temperature value of a specified portion. [Effects of the Invention]

[0010] According to the present invention, the energy generated by the solar cell panel can be used efficiently and safely. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a photovoltaic power generation system using a semiconductor circuit breaker according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a system configuration including a microgrid that realizes local production and consumption of electricity by interchange of DC power. [Figure 3] FIG. 3 is a diagram showing an example of the configuration of a photovoltaic power generation system using a plurality of semiconductor circuit breakers. [Figure 4] FIG. 4 is a diagram illustrating an example of the internal configuration of a semiconductor circuit breaker. [Figure 5] FIG. 5 is a diagram showing another example of the internal configuration of a semiconductor circuit breaker. [Figure 6] FIG. 6 is a flowchart showing an example of the basic operation of the semiconductor circuit breaker (an example of the control flow of the "control unit 40" in FIGS. 4 and 5). [Figure 7] FIG. 7 is a diagram showing an example of a general solar power generation system. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described with reference to the drawings.

[0013] <Basic configuration> Fig. 1 is a diagram showing an example of the configuration of a solar power generation system using a semiconductor circuit breaker according to an embodiment, in which the same reference numerals are used to designate elements common to those in Fig. 7.

[0014] The solar power generation system 1 shown in FIG. 1 includes a plurality of PV panels 11 constituting a solar cell 10, a semiconductor circuit breaker 12 that operates autonomously depending on the situation, a storage battery 13, and a DC / AC converter 14.

[0015] The semiconductor circuit breaker 12 enables the power generated by the PV panel 11 to be supplied to the storage battery 13, a power system (not shown), or a load device without using a power conditioner.

[0016] The semiconductor circuit breaker 12 includes a semiconductor switch connected between the PV panel 11 and the storage battery 13. Specifically, the semiconductor switch is made up of a plurality of semiconductor switching elements, and each semiconductor switching element is configured to be turned on or off depending on the voltage of the storage battery 13 (the voltage of the entire storage battery) and the state of the current flowing through the internal circuit.

[0017] Although details will be described later, semiconductor circuit breaker 12 further includes a control unit that turns on or off at least predetermined semiconductor switching elements among the plurality of semiconductor switching elements according to the voltage, current, or temperature values ​​of predetermined parts of the circuit. This control unit monitors the voltage, current, temperature, remaining capacity (SOC) of storage battery 13, and other conditions of each part through signals supplied from various instruments and the like arranged within semiconductor circuit breaker 12, and controls the on / off of each semiconductor switching element to prevent problematic events such as overcharging of storage battery 13 or overcurrent in the circuit.

[0018] The solar power generation system 1 shown in Fig. 1 uses only one power converter that generates power loss. That is, the only power converter is a DC / AC converter 14 that performs DC / AC conversion. This results in a very high energy efficiency of 0.95, unlike conventional power conditioners that have three power converters.

[0019] Although a DC / AC converter is illustrated here as an example of a power converter, the present invention is not limited to this example, and a DC / DC converter may be used instead. If a DC / DC converter is used, direct current power can be exchanged with other devices or systems via a microgrid or the like. In this case, depending on the situation, it may be possible to omit the installation of a DC / DC converter. If the solar power generation system 1 is connected to a microgrid or the like, it may be possible to realize local production and consumption of power in a specific area, for example, thereby reducing the cost of power.

[0020] <Example of system configuration including a microgrid that realizes local production and consumption> Figure 2 shows an example of a system configuration including a microgrid that realizes local production and consumption of electricity by interchange of DC power.

[0021] FIG. 2 shows an example in which a microgrid (local grid) 20 that enables DC power interchange is employed. The microgrid 20 has a DC bus (DC bus) that can supply DC power of, for example, 1500 V. Various devices or systems that can transmit and receive DC power are connected to the DC microgrid 20, including the semiconductor circuit breaker 12 described above. Here, an example is shown in which a plurality of semiconductor circuit breakers 12 are connected to the microgrid 20.

[0022] Each semiconductor circuit breaker 12 is connected to a PV panel 11 that constitutes a solar cell 10, a grid stabilization battery group 13A (a combination of an appropriate number of batteries 13 for stabilizing the power of the microgrid), and an EV charger / discharger (a charger / discharger for electric vehicles) 15.

[0023] In addition to the multiple semiconductor circuit breakers 12, multiple bidirectional DC / DC converters (power converters that can perform DC / DC conversion in both directions) 21 may be connected to the microgrid 20. Each bidirectional DC / DC converter is connected to a power conditioner-less DC power supply system (a direct current power supply system that does not incorporate a power conditioner) 22, and each power conditioner-less DC power supply system is further connected to devices or systems 23 such as PV panels, wind turbines, and EV chargers / dischargers.

[0024] 2, each semiconductor circuit breaker 12 is connected to the microgrid 20 without using a bidirectional DC / DC converter. In this case, there are advantages such as less occurrence of momentary interruptions and the like, and the system can be constructed at low cost.

[0025] <Configuration example of a solar power generation system using multiple semiconductor circuit breakers> FIG. 3 shows an example of the configuration of a photovoltaic power generation system using multiple semiconductor circuit breakers.

[0026] 3, the PV panel 11 constituting the above-mentioned solar cell 10, the storage battery 13, and the EV charger / discharger 15, as well as a bidirectional DC / AC converter (a power converter that can perform DC / AC conversion in both directions) or a bidirectional DC / DC converter (a power converter that can perform DC / DC conversion in both directions) 31 are connected by a DC bus (DC bus) 30 that can supply DC power of, for example, 380 V to 1500 V. The bidirectional DC / AC converter or bidirectional DC / DC converter 31 is connected to a microgrid 20.

[0027] A plurality of semiconductor circuit breakers 12 that enable power supply / cutoff between each element are installed at key locations on the DC bus 30. In addition, an edge controller 33 is also provided that sends and receives various data to and from each semiconductor circuit breaker 12 via data lines 32. The edge controller 33 can communicate with an external server (not shown) (or a device or system connected to the microgrid 20).

[0028] In such a configuration, the edge controller 33 periodically acquires data indicating the status of each part within each semiconductor circuit breaker 12, such as the voltage, current, temperature, and remaining capacity (SOC) of the storage battery 13, from each semiconductor circuit breaker 12 via the data line 32, and sends the acquired data to a remote server (or equipment or system connected to the microgrid 20), thereby enabling these statuses to be monitored remotely.

[0029] Furthermore, a remote server (or a device or system connected to the microgrid 20) writes data (such as thresholds) indicating conditions for switching the semiconductor switching elements in the semiconductor circuit breakers 12 from an on state to an off state and data (such as thresholds) indicating conditions for switching the semiconductor switching elements from an off state to an on state to a predetermined storage medium in the edge controller 33, and the edge controller 33 sends the written data to the semiconductor circuit breakers 12 via the data line 32, thereby enabling the semiconductor circuit breakers 12 to autonomously control the on / off of the semiconductor switching elements based on the data. For example, each semiconductor circuit breaker 12 can turn off its semiconductor switching element when the voltage of the DC bus 30 reaches the upper limit of the voltage of the storage battery 13. Furthermore, a semiconductor circuit breaker 12 close to a storage battery 13 can turn off its semiconductor switching element and stop discharging when the remaining capacity of the storage battery 13 drops to its limit.

[0030] In addition, in an emergency or during microgrid control, the operation of each semiconductor circuit breaker 12 can be remotely controlled by transmitting any control command to each semiconductor circuit breaker 12 from a remote location using a method similar to that described above.

[0031] <Internal configuration example of a semiconductor circuit breaker> FIG. 4 shows an example of the internal configuration of the semiconductor circuit breaker 12. As shown in FIG.

[0032] The semiconductor circuit breaker 12 shown in FIG. 4 includes a control unit 40, a voltmeter 41, an ammeter 42, a thermometer 43, a communication interface (I / F) 44, a diode D1, and semiconductor switching elements SW1 and SW2.

[0033] The control unit 40 can be configured with a microcontroller. The power source for the control unit 40 may be configured to be obtained from the solar cell 10 or the storage battery 13.

[0034] The voltmeter 41, ammeter 42, and thermometer 43 can be configured with general measurement means. The communication interface 44 can be configured using Ethernet (registered trademark), an RS-485 serial interface, an LED (Light Emitting Diode), a photoelectric sensor, various switches, etc. The diode D1 can be configured with a general diode. The semiconductor switching elements SW1 and SW2 can be configured with a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a bipolar transistor, an IGBT (Insulated Gate Bipolar Transistor), or a SiC-MOSFET.

[0035] The diode D1 directs the current flow between the PV panel 11 and the storage battery 13 and prevents the current from flowing in the reverse direction.

[0036] The voltmeter 41 measures the voltage value between the terminals of the storage battery 13. The measured voltage value is transmitted to the control unit 40.

[0037] The ammeter 42 measures the value of the current flowing between the PV panel 11 and the storage battery 13. The measured value of the current is transmitted to the control unit 40.

[0038] The thermometer 43 measures the temperature value (for example, the temperature value of a specific semiconductor switching element) of a circuit portion through which current flows in the semiconductor circuit breaker 12. The measured temperature value is transmitted to the control unit 40.

[0039] The control unit 40 monitors the status of each part, such as the voltage, current, temperature, and remaining capacity (SOC) of the storage battery 13, through signals supplied from a voltmeter 41, an ammeter 42, and a thermometer 43 arranged within the semiconductor circuit breaker 12, and controls the on / off of the semiconductor switching elements SW1 and SW2 to prevent overcharging of the storage battery 13 or overcurrent in the circuit.

[0040] Furthermore, the control unit 40 receives data indicating various threshold values ​​transmitted from a predetermined controller (for example, a controller equivalent to the above-mentioned edge controller 33) via the communication interface 44. The received data is stored in a predetermined storage medium within the semiconductor circuit breaker 12. The various threshold values ​​indicated in the received data are used for on / off control of the semiconductor switching elements SW1 and SW2.

[0041] The communication interface 44 transmits and receives various data to and from an external server. For example, the communication interface 44 transmits data indicating the status of each part in the semiconductor circuit breaker 12, such as the voltage, current, and temperature, and the remaining capacity (SOC) of the storage battery 13, to the outside, and transmits a corresponding warning when the control unit 40 detects an abnormality. The communication interface 44 also receives data indicating various thresholds transmitted from the outside via a predetermined controller.

[0042] <Various functions of the control unit in Figure 4> The control unit 40 has the function of executing the following various operations as required. Each of these operations will be explained below in order.

[0043] Here, it is assumed that the solar power generation system is in operation and the semiconductor switching elements SW1 and SW2 are in the ON state.

[0044] (1-1) Overcharge prevention operation When the voltage of the storage battery 13 exceeds a predetermined threshold, the control unit 40 turns off the semiconductor switching elements SW1 and SW2. Specifically, when the voltage of the storage battery 13 exceeds the full charge voltage value or when the state of charge (SOC) of the storage battery 13 reaches 100%, the control unit 40 turns off the semiconductor switching elements SW1 and SW2 to complete charging. The full charge voltage value is stored as a setting value in a predetermined storage medium within the semiconductor circuit breaker 12, and the setting can be rewritten externally via the communication interface 44.

[0045] (1-2) Overcurrent protection operation The control unit 40 turns off the semiconductor switching elements SW1 and SW2 when the current flowing between the PV panel 11 and the storage battery 13 exceeds a predetermined threshold. Specifically, the maximum charging current for charging the storage battery is specified by the battery manufacturer, so when the ammeter 42 detects a current from the PV panel 11 or the like that exceeds the maximum charging current, the control unit 40 turns off the semiconductor switching elements SW1 and SW2 and stops charging. At this time, the control unit 40 may issue an alarm to that effect to the outside via the communication interface 44.

[0046] (1-3) Hysteresis operation When the control unit 40 turns off the semiconductor switching elements SW1 and SW2 to stop charging when the storage battery 13 is fully charged, the voltage of the storage battery 13 drops due to the characteristics of the storage battery 13. When the control unit 40 turns on the semiconductor switching elements SW1 and SW2 in response to this voltage drop, the voltage of the storage battery 13 rises again, causing the semiconductor switching elements SW1 and SW2 to frequently cycle on and off. For this reason, a hysteresis voltage is provided so that the semiconductor switching elements SW1 and SW2 are not turned on until the measured voltage of the storage battery 13 drops below the open-circuit voltage of the storage battery 13 when it is fully charged. In this way, hysteresis operation is performed, and the semiconductor switching elements SW1 and SW2 do not frequently cycle on and off.

[0047] (1-4) Overheating prevention operation The control unit 40 turns off the semiconductor switching elements SW1 and SW2 when the temperature of a predetermined portion of the semiconductor circuit breaker 12 exceeds a predetermined threshold. Specifically, the thermometer 43 is arranged so as to be able to measure the temperature of a predetermined semiconductor switching element (one, more than one, or all of the semiconductor switching elements), and when the temperature of a predetermined semiconductor switching element reaches the upper limit of the operating temperature specified by the manufacturer due to an overcurrent, the control unit 40 turns off the semiconductor switching elements SW1 and SW2. At that time, the control unit 40 may issue an alarm indicating this to the outside via the communication interface 44. The conditions for returning the semiconductor circuit breaker 12 to its original state can be set or changed as appropriate.

[0048] (1-5) Battery full charge detection The control unit 40 can detect whether the storage battery 13 is fully charged. The full charge of the storage battery 13 can be detected from the Ah value obtained by integrating the current value inside the semiconductor circuit breaker 12. However, if there is another path to the storage battery 13 and there is a possibility that charging and discharging will proceed simultaneously, the remaining charge (SOC) of the storage battery 13 may be obtained from a control circuit (BMU: Battery Management Unit) on the storage battery 13 side via the communication interface 44, and the full charge may be detected from the SOC. Alternatively, the control unit 40 may obtain information indicating which method to use from the outside via the communication interface 44, and write the obtained information to a predetermined storage medium in the semiconductor circuit breaker 12.

[0049] <Internal configuration example of a bidirectional semiconductor circuit breaker> 5 shows another example of the internal configuration of the semiconductor circuit breaker 12. Here, the explanation will be centered on the parts that are different from FIG.

[0050] The semiconductor circuit breaker 12 shown in FIG. 5 is a bidirectional semiconductor circuit breaker that can selectively form one of the two current flows (charging direction and discharging direction), and can individually control the charging and discharging of the storage battery 13.

[0051] The bidirectional semiconductor circuit breaker 12 includes a control unit 40, a voltmeter 41, an ammeter 42, a thermometer 43, a communication interface (I / F) 44, a voltmeter 45, diodes D11, D12, D13, and D14, and semiconductor switching elements S11, S12, S13, and S14. A DC power supply bus that transmits power discharged from the storage battery 13 and the like is connected to the circuit connecting the semiconductor circuit breaker 12 and the PV panel 11.

[0052] The semiconductor switching elements S11, S12, S13, and S14 are configured, for example, by MOSFETs. Specifically, when the semiconductor switching elements S11 and S14 are on and the semiconductor switching elements S12 and S13 are off, a current in the charging direction flows through the semiconductor switching element S11 and the diode D12, and also flows through the semiconductor switching element S14 and the diode D13. Furthermore, when the semiconductor switching elements S12 and S13 are on and the semiconductor switching elements S11 and S14 are off, a current in the discharging direction flows through the semiconductor switching element S12 and the diode D11, and also flows through the semiconductor switching element S13 and the diode D14.

[0053] The voltmeter 45 measures the value of the voltage of the PV panel 11 (the voltage of the solar cell 10). The value of the voltage measured by the voltmeter 45 is transmitted to the control unit 40.

[0054] The control unit 40 monitors the status of each part, such as the voltage, current, temperature, and remaining capacity (SOC) of the storage battery 13, through signals supplied from a voltmeter 41, a voltmeter 45, an ammeter 42, and a thermometer 43 arranged within the semiconductor circuit breaker 12, and controls the on / off of the semiconductor switching elements S11, S12, S13, and S14 to prevent overcharging of the storage battery 13, overcurrent in the circuit, and over-discharge.

[0055] Furthermore, the control unit 40 receives data indicating various threshold values ​​transmitted from a predetermined controller (for example, the above-mentioned edge controller 33) via the communication interface 44. The received data is stored in a predetermined storage medium within the semiconductor circuit breaker 12. The various threshold values ​​indicated in the received data are used for on / off control of the semiconductor switching elements S11, S12, S13, and S14.

[0056] <Various functions of the control unit in Figure 5> The control unit 40 has the function of executing the following various operations as required. Each of these operations will be explained below in order.

[0057] Here, it is assumed that the solar power generation system is in operation. When the storage battery 13 is being charged, the semiconductor switching elements S11 and S14 are in the ON state, and the semiconductor switching elements S12 and S13 are in the OFF state. When the storage battery 13 is being discharged, the semiconductor switching elements S12 and S13 are in the ON state, and the semiconductor switching elements S11 and S14 are in the OFF state.

[0058] (2-1) Overcharge prevention operation If the voltage of the storage battery 13 exceeds a predetermined threshold while the storage battery 13 is being charged, the control unit 40 turns off the semiconductor switching elements S11 and S14. Specifically, when the voltage of the storage battery 13 exceeds the full charge voltage value or when the state of charge (SOC) of the storage battery 13 reaches 100%, the control unit 40 turns off the semiconductor switching elements S11 and S14 to complete the charging. The full charge voltage value is stored as a setting value in a predetermined storage medium within the semiconductor circuit breaker 12, and the setting can be rewritten externally via the communication interface 44.

[0059] (2-2) Overcurrent protection operation If the current flowing between the PV panel 11 and the storage battery 13 exceeds a predetermined threshold while the storage battery 13 is being charged, the control unit 40 turns off all of the semiconductor switching elements S11, S12, S13, and S14. Specifically, since the maximum charging current for charging a storage battery is specified by the battery manufacturer as described above, if the ammeter 42 detects a current from the PV panel 11 or the like that exceeds the maximum charging current, the control unit 40 turns off all of the semiconductor switching elements S11, S12, S13, and S14, thereby stopping the charging. At this time, the control unit 40 may issue an alarm to that effect to the outside via the communication interface 44.

[0060] (2-3) Overdischarge protection operation If the voltage of the storage battery 13 during discharge falls below a predetermined threshold or if the remaining capacity of the storage battery 13 falls below a threshold, the control unit 40 turns off the semiconductor switching elements S12 and S13 to cut off the current flowing in the discharge direction. Specifically, if the lower limit of the operating voltage of the storage battery 13 is exceeded during discharge or if the remaining capacity (SOC) of the storage battery 13 falls to 0% or below a predetermined value, the control unit 40 turns off the semiconductor switching elements S12 and S13 to stop the discharge. The lower limit of the operating voltage and the SOC threshold of the storage battery 13 can be rewritten externally via the communication interface 44 to match the specifications of the storage battery 13.

[0061] (2-4) Hysteresis operation When the semiconductor switching elements S12 and S13 are turned off to stop discharging due to over-discharge of the storage battery 13, the voltage of the storage battery 13 rises due to the characteristics of the storage battery 13. When the control unit 40 turns on the semiconductor switching elements S12 and S13 in response to this voltage rise, the voltage of the storage battery 13 drops again, causing the semiconductor switching elements S12 and S13 to frequently cycle on and off. For this reason, a hysteresis voltage is provided so that the semiconductor switching elements S12 and S13 are not turned on until the measured voltage of the storage battery 13 rises above the open-circuit voltage at the end of discharging of the storage battery 13. In this way, hysteresis operation is performed, and the semiconductor switching elements S12 and S13 do not frequently cycle on and off.

[0062] (2-5) Overheating prevention operation When the temperature of a predetermined portion of the semiconductor circuit breaker 12 exceeds a predetermined threshold, the control unit 40 turns off the semiconductor switching elements S11, S12, S13, and S14. Specifically, the thermometer 43 is arranged so as to be able to measure the temperature of a predetermined semiconductor switching element (one, more than one, or all of the semiconductor switching elements), and when the temperature of a predetermined semiconductor switching element reaches the upper limit of the operating temperature specified by the manufacturer due to an overcurrent, the control unit 40 turns off the semiconductor switching elements S11, S12, S13, and S14. At this time, the control unit 40 may issue an alarm indicating this to the outside via the communication interface 44. The conditions for returning the semiconductor circuit breaker 12 to its original state can be set or changed as appropriate.

[0063] (2-6) Battery full charge detection The control unit 40 can detect whether the storage battery 13 is fully charged. The full charge of the storage battery 13 can be detected from the Ah value obtained by integrating the current value inside the semiconductor circuit breaker 12. However, if there is another path to the storage battery 13 and there is a possibility that charging and discharging will proceed simultaneously, the remaining charge (SOC) of the storage battery 13 may be obtained from the control circuit (BMU) on the storage battery 13 side via the communication interface 44, and the full charge may be detected from the SOC. Furthermore, the control unit 40 may obtain information indicating which method to use from the outside via the communication interface 44, and write the obtained information to a predetermined storage medium in the semiconductor circuit breaker 12.

[0064] (2-7) Discharge start operation As described above, the remaining capacity (SOC) of the storage battery 13 may be acquired from the control circuit (BMU) on the storage battery 13 side via the communication interface 44. In this case, when the SOC reaches a predetermined value, the control unit 40 permits discharge and starts discharge by turning on the semiconductor switching elements S12 and S13.

[0065] <Example of operation> Next, an example of the basic operation of the semiconductor circuit breaker 12 will be described with reference to the flowchart of Fig. 6. Here, an example of the operation common to the semiconductor circuit breaker 12 having the configuration of Fig. 4 and the semiconductor circuit breaker 12 having the configuration of Fig. 5 will be described.

[0066] The control unit 40 provided in the semiconductor circuit breaker 12 acquires information indicating the status of each part, such as the voltage, current, temperature, and remaining capacity (SOC) of the storage battery 13, through signals supplied from various instruments arranged within the semiconductor circuit breaker 12 (step S1), and continues operation while monitoring the status of each part based on the acquired information (step S2).

[0067] During operation, the control unit 40 constantly monitors the state of each part and checks whether any of the various events anticipated in advance has occurred (step S3).

[0068] For example, it checks whether the temperature of a specific part of the semiconductor circuit breaker 12 exceeds a specific threshold, whether the voltage of the storage battery 13 exceeds a specific threshold, whether the current flowing between the PV panel 11 and the storage battery 13 exceeds a specific threshold, or whether the voltage of the storage battery 13 during discharge is below a specific threshold (or whether the remaining capacity of the storage battery 13 is below a threshold).

[0069] If none of the various presumed events occurs (branch to "No" in step S3), the process is repeated from step S1.

[0070] On the other hand, if any of the various pre-expected events occurs (branch to "Yes" in step S3), the control unit 40 executes a process that is pre-associated with the event that has occurred (step S4).

[0071] For example, if the temperature of a predetermined part of the semiconductor circuit breaker 12 exceeds a predetermined threshold, an overheat prevention operation is performed by turning off a predetermined semiconductor switching element, if the voltage of the storage battery 13 exceeds a predetermined threshold, an overcharge prevention operation is performed by turning off a predetermined semiconductor switching element, if the current flowing between the PV panel 11 and the storage battery 13 exceeds a predetermined threshold, an overcurrent protection operation is performed by turning off a predetermined semiconductor switching element, or if the voltage during discharging of the storage battery 13 falls below a predetermined threshold (or if the remaining capacity of the storage battery 13 falls below a threshold), an overdischarge protection operation is performed by turning off a predetermined semiconductor switching element so as to cut off the current flowing in the discharging direction. Also, a corresponding alarm is issued to the outside as necessary.

[0072] If the process can be carried out without any problems (branch to "Yes" in step S5), the process is repeated from step S1.

[0073] On the other hand, if there is a problem (branching to "No" in step S5), a process previously associated with the problem is executed (step S6). For example, if the temperature of a specific part continues to rise even after overheat prevention operation has been executed, or if the thermometer indicates an abnormal value, measures such as issuing a corresponding alarm to the outside are taken.

[0074] <Summary> As described above in detail, according to the embodiment, the energy generated by the solar cell 10 can be used efficiently and safely.

[0075] That is, the power generated by the solar cell 10 can be efficiently and safely supplied to the storage battery 13, the power grid, etc., without using a power conditioner with a large number of power converters.

[0076] In addition, the following effects can be obtained.

[0077] -Reduction of losses due to power conversion Highly efficient power storage during low output periods (such as on cloudy days) · Guaranteed long-term reliability (improved cutoff performance and longer life) - Cost reduction by reducing the number of parts The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0078] 1...Photovoltaic power generation system, 10...Photovoltaic cell, 11...PV panel (solar panel), 12...Semiconductor circuit breaker, 13...Storage battery, 13A...Grid stabilization storage battery group, 14...DC / AC converter, 15...EV charger / discharger, 20...Microgrid, 21...Bidirectional DC / DC converter, 22...Power conditioner-less DC power supply system, 23...Equipment or system such as PV panel, wind turbine generator, EV charger / discharger, 30...DC bus, 31...Bidirectional DC / AC converter or bidirectional DC / DC converter, 32...DC bus (DC bus), 33...Edge controller, 40...Control unit, 41...Voltmeter, 42...Ammeter, 43...Thermometer, 44...Communication interface (I / F), 45...Voltmeter, D11, D12, D13, D14...Diodes, SW1, SW2...Semiconductor switching elements, S11, S12, S13, S14...MOSFETs.

Claims

1. A semiconductor circuit breaker that enables power generated by a solar panel to be supplied to a storage battery, a power system, or a load device without using a power conditioner, a plurality of semiconductor switching elements connected between the solar panel and the storage battery; a control unit that turns on or off at least a predetermined semiconductor switching element among the plurality of semiconductor switching elements in accordance with a value of a voltage, a current, or a temperature of a predetermined portion; A semiconductor circuit breaker comprising:

2. the control unit turns off at least a predetermined semiconductor switching element among the plurality of semiconductor switching elements when the voltage of the storage battery exceeds a predetermined threshold. The semiconductor circuit breaker of claim 1 .

3. the control unit turns off at least a predetermined semiconductor switching element among the plurality of semiconductor switching elements when a current flowing between the solar cell panel and the storage battery exceeds a predetermined threshold. The semiconductor circuit breaker of claim 1 .

4. the control unit turns off at least a predetermined semiconductor switching element among the plurality of semiconductor switching elements when the temperature of a predetermined portion of the semiconductor circuit breaker exceeds a predetermined threshold. The semiconductor circuit breaker of claim 1 .

5. the control unit turns off at least a predetermined semiconductor switching element among the plurality of semiconductor switching elements so as to cut off a current flowing in a discharging direction when a voltage of the storage battery during discharging falls below a predetermined threshold or when a remaining capacity of the storage battery falls below a threshold. The semiconductor circuit breaker of claim 1 .

6. A photovoltaic power generation system comprising: the semiconductor circuit breaker according to any one of claims 1 to 5; the solar cell panel; and the storage battery.

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